US20070119277A1 - Methods for processing crushed solids with a liquid within a vessel - Google Patents
Methods for processing crushed solids with a liquid within a vessel Download PDFInfo
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- US20070119277A1 US20070119277A1 US11/287,779 US28777905A US2007119277A1 US 20070119277 A1 US20070119277 A1 US 20070119277A1 US 28777905 A US28777905 A US 28777905A US 2007119277 A1 US2007119277 A1 US 2007119277A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/02—Apparatus therefor
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- a liquid is reacted with a particulated or crushed solid (“solids”) to enhance one or the other of the liquid or the solids (or both) for commercial benefit.
- solids particulated or crushed solid
- One common application is to react a liquid “lixiviant” with a solid to extract a soluble compound from the solid by way of percolating or washing the solid with the liquid.
- lixiviant is a liquid used for this purpose.
- This process is commonly described as “leaching”, and is known to various fields of endeavor. Typical examples include extracting valuable metals from ores containing the metals by contacting the ores with a lixiviant.
- the extracted metals will then be in solution with the lixiviant, and can be later removed from the lixiviant by known chemical processes, such as chemical precipitation, to render a relatively pure form of the extracted metals, or a form that can be subsequently processed to render a relatively pure form of the extracted metals.
- One example is to wash ore containing gold with a lixiviant containing cyanide to remove the gold from the ore.
- Other examples include washing oil shales with a solvent to extract petroleum from the shales, and washing coal with a sulfur-extracting liquid to remove sulfur from the coal.
- Yet another example includes contacting contaminated soil with a liquid-borne biological agent (or agents) to thereby decontaminate the soil.
- leach pads often occupy areas covering many acres, and in some cases square miles. Due to the nature of the lixiviants used, and the metals being extracted from the ores, leach pads are typically subject to significant environmental controls to reduce the possibility of potential contamination of soil surrounding the leach pad. Further, the ore leaching process via ore heaps and leach pads is a slow process. Common leach times (i.e., the time between when the ore heap is initially formed and the lixiviant added to the ore heap, and the time when the ore is considered “spent” and is removed from the leach pad) are on the order of months. A six month leach time is not uncommon.
- the basic operational concept is to provide an elevated contact rate of lixiviant and other additives to the surfaces of the ore particles by (a) increasing the surfaces of the ore which can be accessed by the lixiviant by grinding the ore to a particle size that exposes the desired metal or mineral value, (b) vigorously agitating the ore and lixiviant so as to provide an elevated level of contact between unconsumed reaction agents, and (c) to readily remove reaction outputs so as to maintain in majority concentration the unconsumed reaction agents.
- the shortcomings of such a process include: (1) significant capital and operational costs are associated with grinding the ore to a small particle size and vigorously agitating such a dense media as an ore slurry; (2) the processing time required for the desired recovery level—as short as 24 hours in the typical case—in conjunction with the size limitations for a vessel which will afford reasonably good economic access of the agitation mechanical to the ore slurry, necessitates a large number of containment vessels, which in turn necessitates a plant of commensurate size to contain and support the operation of the containment vessels, all of which requires significant capital and real estate to construct; (3) small particle sizes typically present challenges for disposal of spent ore since special impoundments are typically required to de-water and stabilize it as permanent fill; (4) because of the relatively high capital and operating costs of such a leach process, the method is not economical for very low grade ores or ores which require leach times in excess of 24 hours to achieve economic recovery; (5) batch processing contains an inherent limitation in that there is wasted economic time between batch
- Heap leaching is an alternative to vat leaching and attempts to address the limitations of vat leaching with respect to low grade ores and ores that require longer leach recovery times (e.g., using certain oxides and certain sulfides).
- the basic operational concept of heap leaching is to trade-off leach recovery time for leach circuit processing size or volume by (1) secondary or tertiary crushing of the ore instead of grinding to a fine grain size, (2) agglomerating the ore into relatively uniform ore spheres to increase permeability of lixiviant and increase contact effectiveness rather than agitating the ore, (3) stacking in broad, relatively shallow piles on an impermeable layer instead of batching in expensive vessels, (4) sprinkling lixiviant on the ore, letting it trickle down under the action of gravity alone through the ore, and collecting the pregnant solution from perforated pipes on the bottom of the heap rather than submerging the ore within a vat or tank, (5) blowing air into the heap (as in the case
- heap leaching extends leaching technology to lower grade and harder-to-leach ores that are not economically done with vat leaching because of the implied processing volume required, heap leaching is less effective in extracting metals and the like from the ores, primarily due to the absence of submersion of the ore in the lixiviant and agitation of the ore (as in agitated vat leaching).
- a trickle-type application of lixiviant to a stack or pile of ore on a leach pad is channeling of the lixiviant, leaving significant portions of the leach pile without sufficient lixiviant to extract the theoretical maximum recoverable metals using the heap.
- heap leaching Because of the large geometric extents of leach pads and complexity of stacking a stable heap, has been performed almost exclusively with conventional overland conveyors and specialized spreading and reclaim conveyors, which imply high capital and operating costs as compared to the compact plant piping of vat leaching.
- One embodiment provides for a method of processing selected solids with a selected liquid, the method including the steps of providing a vessel, and crushing the solids to not less than a predetermined median particle size.
- the crushed solids define, or are referred to herein, as crushed solids.
- the method also includes the step of reacting the crushed solids with the liquid within the vessel, such that a pregnant leach solution and post-reaction solids are derived. At least some of the reacting of the aforementioned step occurs under conditions of a predetermined hydrostatic head.
- the method further includes the step of migrating the pregnant leach solution and the post-reaction solids through the vessel substantially under the influence of gravity alone.
- the method includes the step of extracting the pregnant leach solution and the post reaction solids from the vessel.
- Another embodiment provides for a method of processing a mine ore with a lixiviant, the method including the step of providing a reaction vessel, wherein the vessel defines solids outlet openings and liquid outlet openings.
- the method also includes the step of crushing the mine ore to not greater than a predetermined size, such that crushed ore is defined or derived.
- the method further includes the steps of reacting the crushed ore with the lixiviant within the reaction vessel, thus deriving a pregnant leach solution and post-reaction solids, and extracting at least some of the pregnant leach solution from the reaction vessel via the liquid outlet openings substantially under the influence of gravity alone.
- the method includes extracting the post-reaction solids and at least some of the pregnant leach solution from the reaction vessel via the solids outlet openings substantially under the influence of gravity alone.
- FIG. 1 is a block diagrammatic view depicting a system that can be used to perform a method according to one embodiment of the invention.
- FIG. 2 is block diagrammatic view depicting details of the system of FIG. 1 .
- FIG. 3A is flowchart depicting a method according to one embodiment of the invention.
- FIG. 3B is a continuation of the flowchart of FIG. 3A .
- FIG. 3C is a continuation of the flowchart of FIG. 3A .
- the present teachings provide methods and apparatus for processing solids such as run-of-mine ore, in a substantially continuous manner, so that one or more materials of interest can be extracted or isolated from the ore and further processed to a condition deliverable to the market place.
- Run-of-Mine Ore Refers to matter comprising at least one material of interest that is to be extracted or separated from the balance of the matter.
- Run-of-mine ore (or, interchangeably, ore) is in essentially the same condition as when it was removed from its natural or native source and, typically (but not exclusively), defines a substantially solid, chunk-like consistency and includes individual particles of substantially varying size.
- materials of interest within such ore include gold, silver, platinum group metals, gallium, lead, germanium, refractory metals, molybdenum, copper, zinc, uranium, cobalt, nickel, light metals, crude oil, caregens, rare earth elements, etc.
- Other ores, comprising other respective materials of interest can also be used.
- Examples of a native source for run-of-mine ore include, but are not limited to, a shaft mine, an open pit mine, a strip mine, etc.
- Lixiviant This refers to any of a number of chemical compounds, typically (but not necessarily) in a liquid state, which chemically reacts with run-of-mine ore so as to dissolve, or “leach”, one or more materials out of the ore and into solution with the lixiviant.
- Non-limiting examples of lixiviant include an aqueous solution of acid or acids, an aqueous solution of acid or acids including an oxidizing agent, an aqueous solution of an alkali or alkali's, sulfuric acid, a solution including sulfuric acid, an aqueous solution of an alkali or alkalis' including an oxidizing agent, an aqueous solution of cyanide including an oxidizing agent, an aqueous solution of sodium or calcium hypochlorite, an aqueous solution of ferrous or ferric sulfate, an aqueous solution of ferrous or ferric sulfate including an oxidizing agent, an aqueous solution including a bacterial catalyst, an aqueous solution of chlorine, an aqueous solution of hydrogen peroxide, a solution of ammonium thiosulfate, or an aqueous solution of air and sulfur dioxide and copper.
- lixiviants can also be used.
- Various embodiments allow the use of a lixiviant (or lixiviants) of typically greater concentration than those used in known heap leaching operations.
- concentration (and/or other characteristics) of a lixiviant can be controlled to tighter tolerances, if desired, during continuous mode operation of various embodiments, as compared to known heap leaching operations.
- PLS Pregnant Leach Solution
- a liquid comprising a lixiviant—in some overall degree of chemical depletion or expenditure—and one or more materials dissolved into solution therewith.
- pregnant leach solution typically results from a chemical reaction between a solid material, such as crushed run-of-mine ore, and a pristine (new, fresh, or regenerated) lixiviant.
- Post-Reaction Solids This term refers to solids, typically in a crushed form, which have reacted with a lixiviant such that at least some amount of one or more materials are dissolved out of the solids.
- post-reaction solids are usually defined by crushed run-of-mine ore that has reacted, to some degree, with a lixiviant as generally defined above. That is, such post-reaction solids are typically defined by crushed ore matter that has been depleted, to some extent, of one or more materials previously present in its original (pre-reaction) condition.
- post-reaction solids will include some quantity (i.e., trace or residual amounts, etc.) of pregnant leach solution (PLS) until and/or unless further treatments or processing steps are performed to remove (e.g., leach) such PLS borne by the PRS.
- PLS pregnant leach solution
- Barren Solution refers to lixiviant that has been previously used within a leach process (i.e., was once a pregnant leach solution) and has been processed or otherwise sufficiently reconstituted (i.e., recycled) so as to be useful in one or more embodiments.
- Non-limiting examples of such recycling steps can include removal of the materials dissolved into solution with the PLS, reconstitution by gas injection or addition of new acid, etc.
- a barren solution is derived that can be used within a wash process in order to leach (soak, or free) another liquid out of a solid material, thus defining an aqueous leachate.
- a barren solution is defined by sufficiently recycling PLS so as to derive a lixiviant in substantially new condition, and which can be used as such.
- FIG. 1 a block diagrammatic view depicts a system 100 that can be used to perform one or more methods in accordance with the present teachings. While the system 100 depicts particular elements used in accordance with one embodiment, it is to be understood that other elements (not shown) can be used, and/or selected ones of those elements shown FIG. 1 can be omitted, in accordance with other embodiments. Thus, the system 100 as depicted in FIG. 1 , is but one of any number of systems that can be used in accordance with the present teachings.
- the system 100 includes a supply of run-of-mine ore (ore) 102 .
- the supply of ore 102 is typically piled in a covered or uncovered fashion to wait further processing, as described hereinafter.
- the system 100 includes a crusher 104 .
- the crusher 104 can be defined by any suitable means for crushing the ore 102 to a predetermined median (or, optionally, a mean, not-less-than, or not-to-exceed) size.
- the crusher 104 is defined by a jaw mill.
- the crusher 104 is defined by a gyratory type or SAG mill.
- One of ordinary skill in the mining engineering arts is aware of numerous such crushers 104 for suitably crushing run-of-mine ore 102 , in accordance with the specific type of ore 102 and/or the desired median crushed size, and further elaboration is not required for purposes herein.
- the crusher 104 is suitably selected and used to crush the run-of-mine ore 102 , thus deriving (i.e., defining) a supply (or stream) of crushed solids (i.e., crushed ore) 106 .
- the system 100 includes a supply of lixiviant 108 .
- the lixiviant 108 can be defined by any suitable such lixiviant as defined above.
- the lixiviant 108 is reacted with the crushed solids 106 in order to derive one or more desired by-products (or effects) of the reaction such as, for example, a pregnant leach solution as defined above.
- the lixiviant 108 can be suitably defined so as to react with the crushed solids 106 such that gold is leached out of the crushed solids 106 and into solution with the lixiviant 108 .
- lixiviants i.e., liquids, etc.
- suitable lixiviants 108 can also be used in accordance with the particular type of crushed solids 106 , the desired reaction to occur therewith, etc.
- One of ordinary skill in the mining or chemical arts is aware of numerous such lixiviants 108 and their respective uses.
- the system 100 of FIG. 1 also includes a slurry preparation tank 107 .
- the slurry preparation tank (hereinafter, slurry prep tank) 107 can be defined by a tank or box-like structure and can (optionally) be lined with a hard coating or other suitable wear- or corrosion-resistant material.
- the slurry prep tank 107 is formed of steel and is lined with ceramic tile.
- Other embodiments of the slurry prep tank 107 respectively formed from other suitable materials, can also be defined and used.
- the slurry prep tank 107 is configured to receive respectively controlled flows of the crushed ore 106 and the lixiviant 108 .
- the slurry prep tank is also configured to receive a flow of a suitable flocculant.
- the slurry prep tank 107 serves as a mixing chamber wherein the crushed ore 106 and lixiviant 108 (and flocculant, if used) are combined so as to define a wetted material (or slurry) stream 109 .
- the slurry prep tank 107 is provided in conjunction with suitable piping or other material conduits so that flow of the crushed ore 106 can be optionally bypassed around the slurry prep tank 107 , while the flow of lixiviant 108 into the slurry prep tank is curtailed.
- the slurry prep tank 107 itself is omitted altogether.
- the system 100 of FIG. 1 further includes a mass flow reactor 110 .
- the mass flow reactor (MFR) 110 is also referred to herein as a vessel.
- MFR mass flow reactor
- One or more embodiments of mass flow reactor 110 suitable for use in accordance with the present teachings is/are described in detail in U.S. patent application Ser. No. 10/447,801, titled METHODS AND APPARATUS FOR PROCESSING MIXTURES OF LIQUIDS AND SOLIDS, as filed with the United States Patent and Trademark Office on May 29, 2003 and as incorporated herein by reference in its entirety.
- the MFR 110 provides a vessel-like structure within which the crushed solids 106 are reacted with the lixiviant 108 .
- the crushed solids 106 and the lixiviant 108 can be received by the MFR 110 as respectively separate flows or as, or in combination with, the slurry stream 109 , in accordance with the desired mode of operation. As depicted in FIG. 1 , it is presumed that reaction of the crushed solids 106 with the lixiviant 108 results in the derivation of post-reaction solids and pregnant leach solution, respectively. Other solids/liquids reactions, resulting in other solid and/or liquid by-products, can also be performed within the MFR 110 .
- the mass flow reactor 110 of FIG. 1 is configured to permit the post-reaction solids and the pregnant leach solution to migrate through the MFR 110 and to be extracted there from substantially under the influence of gravity alone as a stream of post-reaction solids 112 and a stream of pregnant leach solution 114 , respectively.
- the mass flow reactor 110 is distinct, for example, from an agitated vat or other type of ore-handling apparatus wherein driven paddles, augers and/or overall rotary motion are used (whether in conjunction with gravity or not) to forcibly induce ore (or other materials) to migrate from an entry point to an exit point. Further operational aspects of the mass flow reactor 110 will be discussed in detail hereinafter.
- the system 100 of FIG. 1 includes a heat exchanger 115 .
- the heat exchanger 115 receives the flow of PLS 114 from the mass flow reactor 110 .
- the heat exchanger 115 can be defined by any suitable form such as, for example, a plate-and-frame design, a serpentine tube design, a multi-tube single-pass design, etc.
- One of skill in the mechanical engineering arts is aware of numerous heat exchanger 115 designs and their general use and further elaboration is not needed for purpose here.
- the heat exchanger 115 recovers heat from the PLS 114 and routes it (interconnecting means not shown) for pre-heating the lixiviant 108 prior to introduction into the slurry prep tank 107 and/or the MFR 110 .
- such recovered heat is simply expelled to atmosphere via a suitably coupled cooling tower (not shown).
- heat recovered from the heat exchanger 115 is used to pre-heat water or another fluid for use in an electrical generation plant (not shown).
- the pregnant leach solution 114 is cooled to define a cooled PLS stream 117 .
- the heat exchanger 115 is used to heat the PLS 114 to a temperature greater than that as it is received from MFR 110 , prior to subsequent processing of the (heated) PLS 114 . In such a case, the pregnant leach solution is heated to define a heated PLS stream 117 .
- the heat exchanger 115 is optionally bypassed or otherwise inoperative, or the heat exchanger 115 itself is omitted altogether.
- the system 100 includes pregnant leach solution process (PLS process) 116 .
- the PLS process 116 can be defined by any suitable process (or combination of sub-processes) configured to receive the pregnant leach solution stream 114 from the mass flow reactor 110 , the cooled/heated PLS stream 117 from the heat exchanger 115 , and/or the PLS stream 134 (described hereinafter) and to separate (i.e., extract) one or more materials out of the residual pregnant leach solution.
- a suitable PLS process 116 can be defined and used that causes gold to precipitate out of solution with the remaining PLS liquid advancing to the next stage.
- Non-limiting examples of process steps performed by the pregnant leach solution process 116 include any suitable one, or combination of, heating or cooling, clarification, filtration, bulk precipitation, pH modulation, solvent extraction, electrowinning, mercuric retorting, smelting, carbon column absorption, magnetic separation, cyclonic separation, etc.
- process steps performed by the pregnant leach solution process 116 include any suitable one, or combination of, heating or cooling, clarification, filtration, bulk precipitation, pH modulation, solvent extraction, electrowinning, mercuric retorting, smelting, carbon column absorption, magnetic separation, cyclonic separation, etc.
- the pregnant leach solution process 116 includes suitable process steps resulting in the extraction and isolation of one or more minerals, metals, and/or other materials 118 in a condition suitable for provision to the market, or further processing, if desired.
- the PLS process 116 can be defined and operated so as to reconstitute (i.e., recycle) the lixiviant within the PLS stream 114 , 117 and/or 134 , or some fraction thereof, so that a renewed lixiviant stream (or supply) 148 is derived. As depicted in FIG. 1 , the renewed lixiviant 148 is routed back to and combined with the supply or source of lixiviant 108 .
- the PLS process 116 is defined and operated so as to derive a stream (or supply) of barren solution (not shown).
- Other embodiments of the pregnant leach solution process 116 can also be defined and used.
- the system 100 of FIG. 1 also includes a screen process 120 .
- the screen process 120 can include any suitable mesh-like apparatus such as, for example, a mesh conveyer belt, a vibratory screen assembly, etc. Other suitable screen process 120 apparatus can also be used.
- the screen process (or screen) 120 is configured to receive and support the post-reaction solids 112 such that post-reaction solids 112 of less than a predetermined size are separated from the balance of the PRS stream 112 .
- the screen process 120 is configured so that post-reaction solids of less than 5 ⁇ 8 inch, defining fine solids (or “fines”), are separated from the balance of the post-reaction solids 112 .
- the coarse solids 122 are routed onto other processing 126 , which can include any desirable step or combination of steps for handling the relatively coarse solids 122 .
- Such other processing 126 step or steps can include, for example, detoxification and/or disposal of the coarse post-reaction solids 122 , further extraction of another material of interest therefrom, processing and/or market preparation of “cleaned” coal or oil shale (e.g., coal or oil shale from which sulfur has been “washed” or leached within the MFR 110 ), etc.
- One of skill in the mining arts is aware of numerous subsequent steps that can be performed after screen separation of fines from coarse solids, and further elaboration is not needed for purposes herein.
- the system 100 of FIG. 1 further includes a centrifuge process 128 .
- the centrifuge process 128 includes any suitable apparatus configured to receive the fine post-reaction solids (fines) 124 and to additionally separate pregnant leach solution (i.e., PLS 114 ) there from by way of centrifugal force (i.e., rapid rotation within a drum), thus deriving a stream (or supply) of pregnant leach solution 130 .
- the pregnant leach solution 130 can be routed if needed to a clarifying process 132 , described in detail hereinafter.
- the centrifuge process 128 derives a stream (or supply) of generally dried (i.e., “dewatered”) post-reaction solids 136 .
- dewatered generally dried post-reaction solids
- the system 100 also includes a barren solution (or water) wash 140 .
- the barren solution wash 140 can be used to leach additional PLS (i.e., PLS 114 ) out of the (dried, or “dewatered”) fine solids 136 .
- additional PLS i.e., PLS 114
- some fine solids 136 include surface geometry, absorption characteristics, or other considerations that economically justify use of the barren solution wash 140 in order to recover additional material of interest (i.e., cyanide complexed gold, etc.) therefrom.
- the barren solution wash is provided by way of a vessel substantially mechanically equivalent to the mass flow reactor 110 .
- the barren solution (or water) wash 140 derives a stream (or supply) of aqueous leachate 142 borne by the (dried) fine solids as they exit the barren solution wash 140 .
- the fine solids 136 have been “rewetted” by way of soaking (leaching) within the barren solution wash 140 in the interest of recovering additional material of interest therefrom (e.g., dissolved copper, etc.).
- the barren solution or water wash 140 is not used at all.
- the system 100 also includes another centrifuge 144 .
- the centrifuge 144 can be defined by any suitable apparatus configured to receive the stream of “rewetted” fine solids from the barren solution wash 140 and to separate the aqueous leachate 142 therefrom by way of centrifugal force. In this way, the centrifuge 144 derives a stream (or supply) of liquid aqueous leachate 146 and a stream (or supply) of re-dried (or “dewatered”) fine solids 145 . As also depicted in FIG. 1 , re-dried fines solids 145 are optionally routed onto other processing 138 , which can include any desirable step or combination of steps for handling the re-dried fines solids 145 .
- Such other processing 138 step can include, for example, detoxification and/or disposal of the re-dried fines 145 , further extraction of another material of interest therefrom, cyclonic (or other) separation of different sizes (or classes) of fines material 145 , etc.
- detoxification and/or disposal of the re-dried fines 145 can include, for example, detoxification and/or disposal of the re-dried fines 145 , further extraction of another material of interest therefrom, cyclonic (or other) separation of different sizes (or classes) of fines material 145 , etc.
- the system 100 includes a clarifying process 132 .
- the clarifying process 132 can be defined by, or include, any suitable apparatus or processing step (or steps), if any, as desired or required, to remove solids from or otherwise handle the stream of pregnant leach solution 130 generated by the centrifuge process 128 , and/or the aqueous leachate 146 generated by the centrifuge 144 .
- the clarifying process 132 can be suitably defined to remove a substantial fraction of the solids therefrom.
- the clarifying process 132 derives a stream (or supply) of pregnant leach solution 134 to be routed on to the PLS process 116 described above.
- the clarifying process 132 is bypassed or omitted altogether.
- the clarify process 132 can be suitably interconnected to the heat exchanger 115 so as to be heated or cooled thereby.
- the system 100 of FIG. 1 depicts particular system elements (i.e., process apparatus) coupled in particular cooperative relationships. However, it is to be understood that other systems (not shown) can also be defined and used in accordance with various corresponding embodiments. Further exemplary operation of the system 100 will be described hereinafter. While the system 100 of FIG. 1 is described above in terms of processing run-of-mine ore (i.e., 102 ), it is to be understood that another system (not shown), including a mass flow reactor (e.g., MFR 110 , etc.), can also be defined and used for decontaminating soil and the like.
- MFR 110 can provide a basis for any number of substantially continuous processes involving reactions between solid and liquid materials.
- FIG. 2 is a block diagrammatic view depicting selected details of the system 100 of FIG. 1 .
- the mass flow reactor (i.e., vessel) 110 is coupled to receive the stream of crushed solids (i.e., crushed ore) 106 directly—that is, the slurry prep tank 107 of FIG. 1 is not included.
- the mass flow reactor 110 is coupled in fluid communication with the supply of lixiviants 108 .
- the MFR 110 receives the crushed solids 106 via at least one point (or opening) 150 proximate an open top of the MFR 110 .
- the MFR 110 is configured to receive the crushed solids 106 via at least one point (or opening) elevationally lower with respect to the MFR 110 . It is to be understood that the system 100 is suitably equipped to regulate the flow of crushed solids 106 into the mass flow reactor 110 over some predetermined range, including complete shut off (zero flow).
- the mass flow reactor 110 is also configured to receive the lixiviant 108 at a plurality of liquid entry points (or openings) 152 elevationally distributed within the MFR 110 . While not specifically depicted in FIG. 2 , it is understood that the mass flow reactor 110 is suitably equipped (e.g., via valves, pressure regulators, electronic and/or pneumatic controls, etc.) so as to throttle, or regulate, the flow of lixiviant 108 (i.e., liquid) through each of the liquid entry points 152 over some predetermined range, including complete shut off.
- the flow of lixiviant 108 can be independently controlled through each liquid entry point 152 , suitably ganged so as to throttle each liquid entry point 152 flow in unison with the others, etc.
- the MFR 110 is also configured to permit the extraction of post-reaction solids 112 from one or more solids exit points (or openings) 154 .
- at least one such solids exit point 154 is coincident with, or substantially proximate to, a bottom center “B” as defined by the mass flow reactor 110 .
- Other respective suitable locations defined by the MFR 110 can also be used for locating the solids exits points 154 .
- the mass flow reactor 110 is suitably equipped so as to throttle the flow of post-reaction solids 112 through each of the solids exit points 154 over some predetermined range, including complete shut off.
- the flow of post-reaction solids 112 can be independently controlled through each solids exit point 154 , coupled (ganged) so as to throttle each exit point 156 flow in unison with the others, etc.
- the MFR 110 is further configured to permit the extraction of pregnant leach solution 114 at a plurality of liquid exit points (or openings) 156 elevationally distributed within the MFR 110 .
- the mass flow reactor 110 is also suitably equipped so as to throttle (regulate) the flow of lixiviant pregnant leach solution 114 (i.e., liquid) through each of the liquid exit points 156 over some predetermined range, including complete shut off.
- the flow of PLS 114 can be independently controlled though each liquid exit point 156 , ganged such that each liquid exit point 156 flow is throttled in unison with the others, etc.
- the mass flow reactor 110 as depicted by FIG. 2 is configured such that post-reaction solids 112 and pregnant leach solution 114 (as well as, to some respective extents, crushed solids 106 and lixiviant 108 ) are induced to migrate (or flow) thorough the MFR 110 substantially under the influence of gravity alone, in the prevailing direction indicated by the arrow “G”. It is to be further understood, of course, that post-reaction solids 112 and pregnant leach solution 114 also migrate toward their respective solids exit points 154 and liquid exit points 156 , in various directions which deviate from the prevailing direction “G” in order for material (e.g., PRS 112 and PLS 114 ) extraction from the MFR 110 to be performed.
- material e.g., PRS 112 and PLS 114
- substantially under the influence of gravity alone refers to migration or motion of respective materials through the mass flow reactor 110 without the use of other mechanical driving means or influences—for example, the mass flow reactor 110 is devoid of any driven paddles or augers, downward and/or upward liquid jetting, or vibration, shaking, rocking or rotation of the MFR 110 , and wherein gravity accounts for not less than ninety percent of the overall migration-inducing force when the mass flow reactor 110 is operated with a gaseous pressure (other than ambient atmospheric) present over the liquid and/or solids materials being processed within the MFR 110 (e.g., see location “U” in FIG. 2 ).
- a gaseous pressure other than ambient atmospheric
- the mass flow reactor 110 of FIG. 2 is also configured so as to define an internal cavity of volume “V”, and a maximum possible (or working) depth “L” of liquid there in. In this way, it is possible to establish a predetermined hydrostatic head gradient by providing and/or maintaining the corresponding depth “L” of liquid (i.e., lixiviant 108 and PLS 114 ) within the MFR 110 .
- the MFR 110 is configured such that a stratum corresponding to a hydrostatic head “H” in excess of 65 feet of the liquid is present, and can be maintained, within the mass flow reactor 110 .
- Other configurations of MFR 110 corresponding to other (potential) magnitudes of hydrostatic head can also be used.
- the mass flow reactor 110 can be suitably configured to provide a zone (or stratum) where at least some of the reaction of the crushed solids 106 with the lixiviant 108 can take place under a predetermined hydrostatic head “H” of the liquid.
- the MFR 110 can be generally open to ambient atmospheric pressure at an elevationally upper end “U”.
- the MFR 110 is configured such that a non-atmospheric pressure (i.e., a relative vacuum or over-atmospheric pressure) is present over the liquid within the MFR 110 , wherein such pressure—be it atmospheric or not—can be provided by way of any suitably selected gas (e.g., air, O 2 , N 2 , NO x , CO 2 , etc.).
- a non-atmospheric pressure i.e., a relative vacuum or over-atmospheric pressure
- gas e.g., air, O 2 , N 2 , NO x , CO 2 , etc.
- the mass flow reactor 110 is coupled in fluid communication with a supply of gas 158 .
- the MFR 110 receives the gas 158 by way of at least one gas entry point (or opening) 160 .
- gas entry point or points 160 can be selectively located and/or distributed within the MFR 110 as desired or required.
- Non-limiting examples of the gas 158 include an oxygen/air mixture, a sulfur dioxide/air mixture, air, pure oxygen, a gaseous oxidizing agent, or any of these or another suitable gas or gasses dissolved in a liquid or lixiviant that is injected into the reactor 110 via entry port(s) 160 , etc.
- Other suitable gases 158 can also be defined and used in.
- the gas 158 can be an oxygen/air mixture of predetermined ratio that is provided to the MFR 110 for purpose of oxidizing sulfur compounds present within or liberated from the crushed solids 106 so that such oxidized sulfur compounds are more readily handled at some subsequent process (not shown) external to the mass flow reactor 110 .
- the mass flow reactor 110 in the upper end “U” can be suitably equipped with ducting or piping, fume collection hoods, fans, etc. (not shown), so that gases (e.g., the gas 158 , a gaseous by-product or by-products of reaction, etc.) can be captured/collected and routed away from the MFR 110 for containment, processing, etc.
- gases e.g., the gas 158 , a gaseous by-product or by-products of reaction, etc.
- one of ordinary skill in the mining arts is aware of numerous processes in which one or more gases can be injected into a reaction zone for one or more purposes, and further elaboration is not required.
- the mass flow reactor 110 of FIG. 2 can also be coupled to a supply of flocculant 170 that can be controllably introduced into the MFR 110 at one or more flocculant entry points (or openings) 172 .
- the flocculant 170 can be defined by any suitable agent used to cause relatively fine particles of the crushed solids 106 to adhere to one another, thus defining a plurality of larger solids entities.
- the flocculant 170 is defined by any suitable agent that causes such fine particles of the crushed solids 106 to adhere to relatively larger particles (or chunks) of the crushed solids 106 (agglomeration).
- an overall permeability of the crushed solids 106 with respect to the lixiviant (liquid) 108 within the MFR 110 can be suitably affected so as to increase contact between the two.
- the flocculant 170 can be provided to the MFR 110 when such flocculation or agglomeration is desired.
- One of ordinary skill in the mining arts is familiar with the selection and use of flocculants 170 as applied to processing ore “fines”, and further elaboration is not required here.
- a supply of inert solids is provided and selectively used so as to affect and/or stabilize one or more physical characteristics during reaction of solids with liquid(s) within a mass flow reactor (e.g., the MFR 110 , etc.) such as, for example, increasing or decreasing heat conductivity, increasing or decreasing heat absorption, increasing or decreasing heat capacity, etc.
- a mass flow reactor e.g., the MFR 110 , etc.
- Non-limiting examples of such inert solids include steel spheres, etc.
- FIG. 3A is flowchart 200 depicting a method in accordance with one embodiment of the present teachings.
- the method of the flowchart 200 is described hereinafter in reference to system 100 of FIGS. 1 and 2 in the interest of understanding. However, it is to be understood that the method of the flowchart 200 can also be performed using other systems and/or elements (not shown) within the scope of the present teachings. While the flowchart 200 depicts particular method steps and order of execution, it is to be understood that other embodiments that include other respective steps and/or orders of execution can also be used. Thus, the method of the flowchart 200 is exemplary of any number of other such methods within the present scope.
- run-of-mine ore is crushed to a suitable median size.
- a suitable crusher 104 so as to derive (define) crushed solids (i.e., crushed ore) 106 having a median size of approximately 0.375 inches in diameter.
- Other median sizes and/or sizing schemes for the crushed solids 106 can also be used.
- crushed solids 106 are provided directly into the mass flow reactor 110 by way of solids entry point 150 so as to fill the MFR 110 to a predetermined operating depth (i.e., vertical pile dimension) “S”.
- a predetermined operating depth i.e., vertical pile dimension
- the slurry prep tank 107 FIG. 1
- the cavity volume “V” defined by the mass flow reactor 110 is such that 82,700 tons of crushed solids 106 are present when the exemplary depth “S” of eighty feet is achieved. It is important to note that at this time, no material is being extracted from the MFR 110 . Once the desired depth “S” of crushed solids 106 is established in the MFR 110 , the flow thereof is ceased at least for the time being. Also at this time or anytime while filling, any initial amount of flocculant 160 that is desired can be provided into the MFR 110 .
- a predetermined liquid lixiviant 108 ( FIG. 2 ) is provided into the mass flow reactor 110 by way of controlled flow through one or more of the liquid entry points 152 .
- a predetermined operating depth “L” of ninety feet of the lixiviant 108 i.e., liquid
- Other operating depths “L” can also be used.
- the lixiviant 108 is defined by an aqueous solution including cyanide.
- step 208 the crushed solids 106 ( FIG. 2 ) are reacted with the lixiviant 108 within the MFR 110 for a predetermined period of time, or dwell, so as to permit at least one material of interest to be dissolved out of the crushed solids 106 and into solution with the lixiviant 108 .
- the derivation of post-reaction solids 112 and pregnant leach solution 114 is underway.
- the gas 158 can be controllably introduced into the mass flow reactor 110 .
- This dwell time i.e., period of reaction without any extraction of post-reactions solids 112 or pregnant leach solution 114
- step 210 the post-reaction solids 112 ( FIG. 2 ) and the pregnant leach solution 114 (as well as substantially not-yet-reacted lixiviant 108 and crushed solids 106 ) begin to migrate through the mass flow reactor 110 in the prevailing direction “G”, by way of gravity alone. In this initial instance, such migration is generally due to settling of material due to the liquid-bath conditions present in the MFR 110 .
- step 212 the extraction of post-reaction solids 112 ( FIG. 2 ) via one or more of the solids exits points 154 begins.
- the extraction of pregnant leach solution 114 by way of one or more of the liquid exit points 156 is also begun.
- the extraction of the post-reaction solids 112 is generally performed in a controlled fashion so that the volumetric (or mass) flow of the post-reaction solids 112 follows a predetermined pattern or scheme, defining a solids extraction flow rate.
- the extraction of pregnant leach solution 114 is also performed in a predetermined controlled-flow manner, defining a liquid extraction flow rate.
- Such solids and liquids extraction flow rates can be, respectively, substantially constant, increase or decrease linearly or non-linearly over time, etc.
- any desired flow rate characteristic can be independently employed in regard to the extraction of post-reaction solids 112
- any desired flow rate characteristic can be employed, up to the maximum permeability rate, in regard to the extraction of pregnant leach solution 114 .
- the extraction of PRS 112 and PLS 114 is performed substantially under the influence of gravity alone as previously described above.
- step 212 the introduction (or addition) of crushed solids 106 ( FIG. 2 ) into the MFR 110 is performed at a rate in accordance with the extraction of post-reaction solids 112 .
- lixiviant 108 is added to the MFR 110 at a rate corresponding to the extraction of pregnant leach solution 114 .
- crushed solids 106 are added to, and post-reaction solids 112 are extracted from, the mass flow reactor 110 in a simultaneous fashion such that a “mass flow” or migration (substantially under the influence of gravity alone) of solid material through the MFR 110 is established and maintained for a predetermined period of time.
- this simultaneous flow of crushed solids 106 and post-reaction solids 112 is maintained for a period of at least of at least 3 days.
- the crushed solids 106 and the post-reaction solids 112 are extracted at substantially equal and/or constant rates, such that the predetermined depth “S” of solids (e.g., eighty feet, etc.) within the MFR 110 is generally maintained constant during this “simultaneous flow” period.
- lixiviant 108 is added to, and pregnant leach solution 114 (as well as any trace and/or incidental amount of PLS borne by the PRS 112 ) is extracted from, the MFR 110 in a simultaneous fashion, such that a gravity-driven mass flow or migration of liquid material through the MFR 110 is established and maintained for a period of time.
- this simultaneous flow of lixiviant 108 and pregnant leach solution 114 is maintained for a period of at least 3 days.
- the respective flow rates of the lixiviant 108 and the pregnant leach solution 114 are controlled at substantially equal and/or constant rates, such that the predetermined liquid depth “L” (e.g., ninety feet, etc.) is maintained essentially constant within the MFR 110 during the time of simultaneous flows.
- the predetermined liquid depth “L” e.g., ninety feet, etc.
- step 214 the post-reaction solids 112 ( FIG. 1 ) are routed to a screen process 120 .
- post-reaction solids 112 of less than a predetermined size are separated from the balance of the post-reaction solids 112 , thus defining a stream (or supply) of relatively coarse post-reaction solids 122 , and a stream (or supply) of fine post-reactions solids (or “fines”) 124 .
- the screen process 120 is defined and provided such that the fines 124 are comprised of individual particles less than five-eights inch in size.
- sizing (or classifying) schemes can also be used in separating fines 124 from coarse post-reaction solids 122 .
- the coarse post-reaction solids 122 ( FIG. 1 ) are then routed to suitable other processing 126 such as, for example, detoxification, disposal, heaping for later processing, etc.
- step 216 the stream of fine post-reactions solids 124 ( FIG. 1 ) are received by a centrifuge process 128 where additional pregnant leach solution (i.e., PLS 114 ) is extracted from the fines 124 resulting in a stream (or supply) of pregnant leach solution 130 .
- additional pregnant leach solution i.e., PLS 114
- other equipment such as filters could be used instead of the centrifuge process 128 .
- Fine post-reaction solids exit the centrifuge process 128 and define a stream (or supply) of dried fines 136 . While such are referred to as “dried”, it is to be understood that relatively small quantities of PLS 114 may still be present on, or absorbed within, the dried fines 136 . This aspect of the dried fines 136 will be considered in further detail below.
- step 218 the stream of pregnant leach solution 130 ( FIG. 1 ) is received by a clarifying process 132 .
- the clarifying process 132 removes solids from the PLS 130 , by a gravity type clarifier, a cyclonic type clarifier, by filters, or by any suitable known means, so as to derive a relatively low-solids stream (or supply) of pregnant leach solution 134 .
- subsequent PLS 134 processing can be performed with greater efficiency and/or efficacy as most of the solids in the solution have been removed.
- the clarifying process 132 is omitted altogether, and the stream (or supply) of PLS 130 directly defines the stream (or supply) of PLS 134 by way of, for example, carbon columns treating dilute gold solutions.
- the dried fines 136 are (optionally) routed to a barren solution (or water) wash 140 .
- the barren solution wash 140 is essentially a barren solution filled vessel in which the dried fines 136 are soaked for some period of time so as to further extract (i.e., leach) relatively small or trace amounts of pregnant leach solution (i.e., PLS 114 ) from the dried fines 136 .
- the barren solution wash 140 is used only when the material of interest (i.e., gold, platinum, etc.) dissolved into the pregnant leach solution (i.e., PLS 114 ) is of sufficient value to economically warrant such extra processing.
- the barren solution wash 140 derives a stream (or supply) of aqueous leachate 142 borne by the “rewetted” fine solids.
- aqueous leachate 142 borne by the “rewetted” fine solids.
- the fines bearing the aqueous leachate 142 are routed to other processing 138 , where the aqueous leachate 142 is separated from the fines (e.g., by way of centrifugal separation 144 , a filter arrangement (not shown), etc.) and thereafter combined with the PLS stream 134 for additional processing at step 222 below.
- any non-washed fine solids 136 are sent to respective other processing 138 and are discarded, etc.
- the dried fines 136 are simply routed to other processing 138 for detoxification, disposal, etc., as desired.
- step 222 the respective streams (or supplies) of pregnant leach solution 114 ( FIG. 1 ) and 134 are received at a pregnant leach solution process 116 .
- the heat exchanger 115 FIG. 1
- any suitable process step or combination of steps and/or apparatus is/are used to extract at least a majority of the material of interest from the aggregate pregnant leach solution ( 114 and 134 of FIG. 1 ).
- the recovered material of interest (e.g., gold, etc.) is then sent on to step 224 ( FIG. 3C ) below.
- the residual liquid of processing the pregnant leach solution ( 114 and 134 of FIG. 1 ) is assumed to be processed as desired by way of regeneration, destruction, containment and disposal, etc.
- step 224 the recovered material of interest from step 222 above is finally processed as needed so as to be delivered to the market place.
- the steps 222 and/or 224 are typically performed so as to isolate at least one material of interest, as originally present in the run-of-mine ore 102 ( FIG. 1 ), in a form that can be provided to (i.e., sold within) the market.
- the exemplary method of the flowchart 200 is presumed to be completely described.
- reaction of crushed solids with lixiviant can be performed within a vessel, otherwise referred to as a mass flow reactor, as a substantially continuous process;
- Solid and liquid materials migrate through, and are extracted from, a mass flow reactor substantially under the influence of gravity alone and without the use of other relevant mechanical means or forces such as, for example, driven paddles, augers, downward and/or upward liquid jetting, or vibrating, rocking, shaking, and/or rotating the mass flow reactor, and wherein gravity is not less than ninety percent of the migration-inducing force when gaseous pressure is present over the materials within the mass flow reactor;
- At least some of the reaction of crushed solids with liquid within a mass flow reactor can be performed under conditions of a predetermined hydrostatic head of the liquid;
- a flocculant can be used, if desired, to affect the permeability of crushed solids with respect to liquid within a mass flow reactor. In this way, liquid-on-solid contact, and the corresponding reaction between solids and liquids, can be suitably increased;
- a gas can be injected into a mass flow reactor so as to oxidize or otherwise chemically affect compounds present during the reaction of crushed solids with liquid.
- One or more physical and/or chemical variables can be suitably controlled within the mass flow reactor during processing, by any respectively suitable known means.
- Non-limiting examples of such variables include pH, Eh (i.e., electron potential in solution), temperature, viscosity, the concentration of a gas, the concentration of a liquid, etc.
- a suitable inert solid can be used, if desired, to affect—increase, decrease or stabilize—one or more characteristics within a mass flow reactor during a reaction between solids and a liquid or liquids.
- Non-limiting examples of such characteristics include heat conductivity, heat absorption, etc.
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Abstract
A method is provided in which solids, such as run-of-mine ore, are crushed and reacted with a liquid within a mass flow reactor as a substantially continuous process. The reaction can include dissolving at least one material out of the crushed solids and into solution with the liquid. Solid and liquid materials migrate through and are extracted from the mass flow reactor substantially under the influence of gravity alone and without the use of other relevant driving means or forces. The respective flows of solid and liquid materials through the mass flow reactor can be controlled so as to maintain generally constant levels of each therein. At least some of the reaction can occur under a predetermined hydrostatic head of the liquid. Further processing of the solid and liquid materials can be performed, including isolation of at least one material of interest extracted from the crushed solids.
Description
- Many applications are known wherein a liquid is reacted with a particulated or crushed solid (“solids”) to enhance one or the other of the liquid or the solids (or both) for commercial benefit. One common application is to react a liquid “lixiviant” with a solid to extract a soluble compound from the solid by way of percolating or washing the solid with the liquid. (Accordingly, a “lixiviant” is a liquid used for this purpose.) This process is commonly described as “leaching”, and is known to various fields of endeavor. Typical examples include extracting valuable metals from ores containing the metals by contacting the ores with a lixiviant. The extracted metals will then be in solution with the lixiviant, and can be later removed from the lixiviant by known chemical processes, such as chemical precipitation, to render a relatively pure form of the extracted metals, or a form that can be subsequently processed to render a relatively pure form of the extracted metals. One example is to wash ore containing gold with a lixiviant containing cyanide to remove the gold from the ore. Other examples include washing oil shales with a solvent to extract petroleum from the shales, and washing coal with a sulfur-extracting liquid to remove sulfur from the coal. Yet another example includes contacting contaminated soil with a liquid-borne biological agent (or agents) to thereby decontaminate the soil.
- In all of these processes the volumes of solids to be treated are typically considerable—on the order of tens to thousands of metric tons per day. In the case of ore leaching (to remove valuable metals from ores containing the metals), the most common process is to pile the ore into a “heap” on a leach pad, and then to introduce a lixiviant onto the top of the heap. After the lixiviant has passed through the ore heap via gravity, the lixiviant is collected and processed to remove the extracted metals from the lixiviant. The spent ore is then discarded (as for example by moving it to a spent ore pile), and new unprocessed ore is then placed on the leach pad, and the process repeated. Such leach pads often occupy areas covering many acres, and in some cases square miles. Due to the nature of the lixiviants used, and the metals being extracted from the ores, leach pads are typically subject to significant environmental controls to reduce the possibility of potential contamination of soil surrounding the leach pad. Further, the ore leaching process via ore heaps and leach pads is a slow process. Common leach times (i.e., the time between when the ore heap is initially formed and the lixiviant added to the ore heap, and the time when the ore is considered “spent” and is removed from the leach pad) are on the order of months. A six month leach time is not uncommon.
- Other prior leaching methods and apparatus include: (1) batch tank leaching, (2) agitated vat leaching, (3) counter-current tank leaching, (4) permanent pad heap leaching (described briefly above), (5) re-usable pad heap leaching, and (6) bio-heap leaching. A common description for each of these methods and apparatus is a “leach circuit”.
- The specific shortcomings of the prior art are as follows.
- For agitated vat leaching, the basic operational concept is to provide an elevated contact rate of lixiviant and other additives to the surfaces of the ore particles by (a) increasing the surfaces of the ore which can be accessed by the lixiviant by grinding the ore to a particle size that exposes the desired metal or mineral value, (b) vigorously agitating the ore and lixiviant so as to provide an elevated level of contact between unconsumed reaction agents, and (c) to readily remove reaction outputs so as to maintain in majority concentration the unconsumed reaction agents.
- The shortcomings of such a process include: (1) significant capital and operational costs are associated with grinding the ore to a small particle size and vigorously agitating such a dense media as an ore slurry; (2) the processing time required for the desired recovery level—as short as 24 hours in the typical case—in conjunction with the size limitations for a vessel which will afford reasonably good economic access of the agitation mechanical to the ore slurry, necessitates a large number of containment vessels, which in turn necessitates a plant of commensurate size to contain and support the operation of the containment vessels, all of which requires significant capital and real estate to construct; (3) small particle sizes typically present challenges for disposal of spent ore since special impoundments are typically required to de-water and stabilize it as permanent fill; (4) because of the relatively high capital and operating costs of such a leach process, the method is not economical for very low grade ores or ores which require leach times in excess of 24 hours to achieve economic recovery; (5) batch processing contains an inherent limitation in that there is wasted economic time between batch operations; and (6) because of the complexity of such a mechanically intensive process, design and construction times for the plant are relatively long (as compared to heap leaching, for example).
- Heap leaching is an alternative to vat leaching and attempts to address the limitations of vat leaching with respect to low grade ores and ores that require longer leach recovery times (e.g., using certain oxides and certain sulfides). The basic operational concept of heap leaching is to trade-off leach recovery time for leach circuit processing size or volume by (1) secondary or tertiary crushing of the ore instead of grinding to a fine grain size, (2) agglomerating the ore into relatively uniform ore spheres to increase permeability of lixiviant and increase contact effectiveness rather than agitating the ore, (3) stacking in broad, relatively shallow piles on an impermeable layer instead of batching in expensive vessels, (4) sprinkling lixiviant on the ore, letting it trickle down under the action of gravity alone through the ore, and collecting the pregnant solution from perforated pipes on the bottom of the heap rather than submerging the ore within a vat or tank, (5) blowing air into the heap (as in the case of bio-heap leaching), and (6) removing the ore continuously from the pad as in the case of re-usable pads to make heap leaching a more continuous rather than a batch process.
- Although heap leaching extends leaching technology to lower grade and harder-to-leach ores that are not economically done with vat leaching because of the implied processing volume required, heap leaching is less effective in extracting metals and the like from the ores, primarily due to the absence of submersion of the ore in the lixiviant and agitation of the ore (as in agitated vat leaching). Of particular concern in the use of a trickle-type application of lixiviant to a stack or pile of ore on a leach pad is channeling of the lixiviant, leaving significant portions of the leach pile without sufficient lixiviant to extract the theoretical maximum recoverable metals using the heap.
- Another inherent shortcoming of heap leach is the inability to control environmental inputs such as temperature and oxygenation of the heap, which are critical factors in bio-heap leaching where the effectiveness of the bacteria is closely dependent on these variables.
- Perhaps the greatest shortcoming of heap leaching is the capital and operating costs associated with large volumes of material, especially in the case of re-usable pads. Whereas in vat leaching the ore is transported in a slurry in pipe conduits, heap leaching, because of the large geometric extents of leach pads and complexity of stacking a stable heap, has been performed almost exclusively with conventional overland conveyors and specialized spreading and reclaim conveyors, which imply high capital and operating costs as compared to the compact plant piping of vat leaching.
- What is needed then is an economical, efficient method and/or apparatus to react solids and liquids with one another that achieves the benefits to be derived from similar prior art apparatus and methods, but which avoid the shortcomings and detriments individually associated therewith.
- One embodiment provides for a method of processing selected solids with a selected liquid, the method including the steps of providing a vessel, and crushing the solids to not less than a predetermined median particle size. The crushed solids define, or are referred to herein, as crushed solids. The method also includes the step of reacting the crushed solids with the liquid within the vessel, such that a pregnant leach solution and post-reaction solids are derived. At least some of the reacting of the aforementioned step occurs under conditions of a predetermined hydrostatic head. The method further includes the step of migrating the pregnant leach solution and the post-reaction solids through the vessel substantially under the influence of gravity alone. Furthermore, the method includes the step of extracting the pregnant leach solution and the post reaction solids from the vessel.
- Another embodiment provides for a method of processing a mine ore with a lixiviant, the method including the step of providing a reaction vessel, wherein the vessel defines solids outlet openings and liquid outlet openings. The method also includes the step of crushing the mine ore to not greater than a predetermined size, such that crushed ore is defined or derived. The method further includes the steps of reacting the crushed ore with the lixiviant within the reaction vessel, thus deriving a pregnant leach solution and post-reaction solids, and extracting at least some of the pregnant leach solution from the reaction vessel via the liquid outlet openings substantially under the influence of gravity alone. The method includes extracting the post-reaction solids and at least some of the pregnant leach solution from the reaction vessel via the solids outlet openings substantially under the influence of gravity alone.
- These and other aspects and embodiments will now be described in detail with reference to the accompanying drawings, wherein:
-
FIG. 1 is a block diagrammatic view depicting a system that can be used to perform a method according to one embodiment of the invention. -
FIG. 2 is block diagrammatic view depicting details of the system ofFIG. 1 . -
FIG. 3A is flowchart depicting a method according to one embodiment of the invention. -
FIG. 3B is a continuation of the flowchart ofFIG. 3A . -
FIG. 3C is a continuation of the flowchart ofFIG. 3A . - In representative embodiments, the present teachings provide methods and apparatus for processing solids such as run-of-mine ore, in a substantially continuous manner, so that one or more materials of interest can be extracted or isolated from the ore and further processed to a condition deliverable to the market place.
- The following terms are defined as used herein:
- Run-of-Mine Ore: Refers to matter comprising at least one material of interest that is to be extracted or separated from the balance of the matter. Run-of-mine ore (or, interchangeably, ore) is in essentially the same condition as when it was removed from its natural or native source and, typically (but not exclusively), defines a substantially solid, chunk-like consistency and includes individual particles of substantially varying size. Non-limiting examples of materials of interest within such ore include gold, silver, platinum group metals, gallium, lead, germanium, refractory metals, molybdenum, copper, zinc, uranium, cobalt, nickel, light metals, crude oil, caregens, rare earth elements, etc. Other ores, comprising other respective materials of interest, can also be used. Examples of a native source for run-of-mine ore include, but are not limited to, a shaft mine, an open pit mine, a strip mine, etc.
- Lixiviant: This refers to any of a number of chemical compounds, typically (but not necessarily) in a liquid state, which chemically reacts with run-of-mine ore so as to dissolve, or “leach”, one or more materials out of the ore and into solution with the lixiviant. Non-limiting examples of lixiviant include an aqueous solution of acid or acids, an aqueous solution of acid or acids including an oxidizing agent, an aqueous solution of an alkali or alkali's, sulfuric acid, a solution including sulfuric acid, an aqueous solution of an alkali or alkalis' including an oxidizing agent, an aqueous solution of cyanide including an oxidizing agent, an aqueous solution of sodium or calcium hypochlorite, an aqueous solution of ferrous or ferric sulfate, an aqueous solution of ferrous or ferric sulfate including an oxidizing agent, an aqueous solution including a bacterial catalyst, an aqueous solution of chlorine, an aqueous solution of hydrogen peroxide, a solution of ammonium thiosulfate, or an aqueous solution of air and sulfur dioxide and copper. Other suitable lixiviants can also be used. Various embodiments allow the use of a lixiviant (or lixiviants) of typically greater concentration than those used in known heap leaching operations. Furthermore, the concentration (and/or other characteristics) of a lixiviant can be controlled to tighter tolerances, if desired, during continuous mode operation of various embodiments, as compared to known heap leaching operations.
- Pregnant Leach Solution (PLS): This refers to a liquid comprising a lixiviant—in some overall degree of chemical depletion or expenditure—and one or more materials dissolved into solution therewith. Thus, pregnant leach solution typically results from a chemical reaction between a solid material, such as crushed run-of-mine ore, and a pristine (new, fresh, or regenerated) lixiviant.
- Post-Reaction Solids (PRS): This term refers to solids, typically in a crushed form, which have reacted with a lixiviant such that at least some amount of one or more materials are dissolved out of the solids. As used herein, post-reaction solids are usually defined by crushed run-of-mine ore that has reacted, to some degree, with a lixiviant as generally defined above. That is, such post-reaction solids are typically defined by crushed ore matter that has been depleted, to some extent, of one or more materials previously present in its original (pre-reaction) condition. In some cases, post-reaction solids (PRS) will include some quantity (i.e., trace or residual amounts, etc.) of pregnant leach solution (PLS) until and/or unless further treatments or processing steps are performed to remove (e.g., leach) such PLS borne by the PRS.
- Barren Solution: Generally, this term refers to lixiviant that has been previously used within a leach process (i.e., was once a pregnant leach solution) and has been processed or otherwise sufficiently reconstituted (i.e., recycled) so as to be useful in one or more embodiments. Non-limiting examples of such recycling steps can include removal of the materials dissolved into solution with the PLS, reconstitution by gas injection or addition of new acid, etc. In one example, a barren solution is derived that can be used within a wash process in order to leach (soak, or free) another liquid out of a solid material, thus defining an aqueous leachate. In another example, a barren solution is defined by sufficiently recycling PLS so as to derive a lixiviant in substantially new condition, and which can be used as such.
- Turning now to
FIG. 1 , a block diagrammatic view depicts asystem 100 that can be used to perform one or more methods in accordance with the present teachings. While thesystem 100 depicts particular elements used in accordance with one embodiment, it is to be understood that other elements (not shown) can be used, and/or selected ones of those elements shownFIG. 1 can be omitted, in accordance with other embodiments. Thus, thesystem 100 as depicted inFIG. 1 , is but one of any number of systems that can be used in accordance with the present teachings. - The
system 100 includes a supply of run-of-mine ore (ore) 102. The supply ofore 102 is typically piled in a covered or uncovered fashion to wait further processing, as described hereinafter. - The
system 100 includes acrusher 104. Thecrusher 104 can be defined by any suitable means for crushing theore 102 to a predetermined median (or, optionally, a mean, not-less-than, or not-to-exceed) size. In one embodiment, thecrusher 104 is defined by a jaw mill. In other respective embodiments, thecrusher 104 is defined by a gyratory type or SAG mill. One of ordinary skill in the mining engineering arts is aware of numeroussuch crushers 104 for suitably crushing run-of-mine ore 102, in accordance with the specific type ofore 102 and/or the desired median crushed size, and further elaboration is not required for purposes herein. In any case, thecrusher 104 is suitably selected and used to crush the run-of-mine ore 102, thus deriving (i.e., defining) a supply (or stream) of crushed solids (i.e., crushed ore) 106. - The
system 100 includes a supply oflixiviant 108. Thelixiviant 108 can be defined by any suitable such lixiviant as defined above. Thelixiviant 108 is reacted with the crushedsolids 106 in order to derive one or more desired by-products (or effects) of the reaction such as, for example, a pregnant leach solution as defined above. For example, thelixiviant 108 can be suitably defined so as to react with the crushedsolids 106 such that gold is leached out of the crushedsolids 106 and into solution with thelixiviant 108. Other suitable lixiviants (i.e., liquids, etc.) 108 can also be used in accordance with the particular type of crushedsolids 106, the desired reaction to occur therewith, etc. One of ordinary skill in the mining or chemical arts is aware of numeroussuch lixiviants 108 and their respective uses. - The
system 100 ofFIG. 1 also includes aslurry preparation tank 107. The slurry preparation tank (hereinafter, slurry prep tank) 107 can be defined by a tank or box-like structure and can (optionally) be lined with a hard coating or other suitable wear- or corrosion-resistant material. In one embodiment, theslurry prep tank 107 is formed of steel and is lined with ceramic tile. Other embodiments of theslurry prep tank 107, respectively formed from other suitable materials, can also be defined and used. Theslurry prep tank 107 is configured to receive respectively controlled flows of the crushedore 106 and thelixiviant 108. In another embodiment (not shown), the slurry prep tank is also configured to receive a flow of a suitable flocculant. Theslurry prep tank 107 serves as a mixing chamber wherein the crushedore 106 and lixiviant 108 (and flocculant, if used) are combined so as to define a wetted material (or slurry)stream 109. In another embodiment of the system 100 (not shown), theslurry prep tank 107 is provided in conjunction with suitable piping or other material conduits so that flow of the crushedore 106 can be optionally bypassed around theslurry prep tank 107, while the flow oflixiviant 108 into the slurry prep tank is curtailed. In yet another embodiment of the system 100 (not shown), theslurry prep tank 107 itself is omitted altogether. - The
system 100 ofFIG. 1 further includes amass flow reactor 110. The mass flow reactor (MFR) 110 is also referred to herein as a vessel. One or more embodiments ofmass flow reactor 110 suitable for use in accordance with the present teachings is/are described in detail in U.S. patent application Ser. No. 10/447,801, titled METHODS AND APPARATUS FOR PROCESSING MIXTURES OF LIQUIDS AND SOLIDS, as filed with the United States Patent and Trademark Office on May 29, 2003 and as incorporated herein by reference in its entirety. TheMFR 110 provides a vessel-like structure within which the crushedsolids 106 are reacted with thelixiviant 108. The crushedsolids 106 and thelixiviant 108 can be received by theMFR 110 as respectively separate flows or as, or in combination with, theslurry stream 109, in accordance with the desired mode of operation. As depicted inFIG. 1 , it is presumed that reaction of the crushedsolids 106 with thelixiviant 108 results in the derivation of post-reaction solids and pregnant leach solution, respectively. Other solids/liquids reactions, resulting in other solid and/or liquid by-products, can also be performed within theMFR 110. - The
mass flow reactor 110 ofFIG. 1 is configured to permit the post-reaction solids and the pregnant leach solution to migrate through theMFR 110 and to be extracted there from substantially under the influence of gravity alone as a stream ofpost-reaction solids 112 and a stream ofpregnant leach solution 114, respectively. In this way, themass flow reactor 110 is distinct, for example, from an agitated vat or other type of ore-handling apparatus wherein driven paddles, augers and/or overall rotary motion are used (whether in conjunction with gravity or not) to forcibly induce ore (or other materials) to migrate from an entry point to an exit point. Further operational aspects of themass flow reactor 110 will be discussed in detail hereinafter. - The
system 100 ofFIG. 1 includes aheat exchanger 115. Theheat exchanger 115 receives the flow ofPLS 114 from themass flow reactor 110. Theheat exchanger 115 can be defined by any suitable form such as, for example, a plate-and-frame design, a serpentine tube design, a multi-tube single-pass design, etc. One of skill in the mechanical engineering arts is aware ofnumerous heat exchanger 115 designs and their general use and further elaboration is not needed for purpose here. In one example, theheat exchanger 115 recovers heat from thePLS 114 and routes it (interconnecting means not shown) for pre-heating thelixiviant 108 prior to introduction into theslurry prep tank 107 and/or theMFR 110. In another example, such recovered heat is simply expelled to atmosphere via a suitably coupled cooling tower (not shown). In yet another example, heat recovered from theheat exchanger 115 is used to pre-heat water or another fluid for use in an electrical generation plant (not shown). In any of these examples, thepregnant leach solution 114 is cooled to define a cooledPLS stream 117. In yet another example, theheat exchanger 115 is used to heat thePLS 114 to a temperature greater than that as it is received fromMFR 110, prior to subsequent processing of the (heated)PLS 114. In such a case, the pregnant leach solution is heated to define aheated PLS stream 117. In yet another embodiment of the system 100 (not shown), theheat exchanger 115 is optionally bypassed or otherwise inoperative, or theheat exchanger 115 itself is omitted altogether. - The
system 100 includes pregnant leach solution process (PLS process) 116. ThePLS process 116 can be defined by any suitable process (or combination of sub-processes) configured to receive the pregnantleach solution stream 114 from themass flow reactor 110, the cooled/heated PLS stream 117 from theheat exchanger 115, and/or the PLS stream 134 (described hereinafter) and to separate (i.e., extract) one or more materials out of the residual pregnant leach solution. For example, asuitable PLS process 116 can be defined and used that causes gold to precipitate out of solution with the remaining PLS liquid advancing to the next stage. Non-limiting examples of process steps performed by the pregnantleach solution process 116 include any suitable one, or combination of, heating or cooling, clarification, filtration, bulk precipitation, pH modulation, solvent extraction, electrowinning, mercuric retorting, smelting, carbon column absorption, magnetic separation, cyclonic separation, etc. One of ordinary skill in the mining engineering arts is aware of numerous, well-established methods and materials for extracting particular materials out of pregnant leach solution and specific definition and elaboration is not required. - In any case, the pregnant
leach solution process 116 includes suitable process steps resulting in the extraction and isolation of one or more minerals, metals, and/orother materials 118 in a condition suitable for provision to the market, or further processing, if desired. Also, thePLS process 116 can be defined and operated so as to reconstitute (i.e., recycle) the lixiviant within thePLS stream FIG. 1 , the renewedlixiviant 148 is routed back to and combined with the supply or source oflixiviant 108. In another embodiment (not shown), thePLS process 116 is defined and operated so as to derive a stream (or supply) of barren solution (not shown). Other embodiments of the pregnantleach solution process 116 can also be defined and used. - The
system 100 ofFIG. 1 also includes ascreen process 120. Thescreen process 120 can include any suitable mesh-like apparatus such as, for example, a mesh conveyer belt, a vibratory screen assembly, etc. Othersuitable screen process 120 apparatus can also be used. The screen process (or screen) 120 is configured to receive and support thepost-reaction solids 112 such thatpost-reaction solids 112 of less than a predetermined size are separated from the balance of thePRS stream 112. In one embodiment, thescreen process 120 is configured so that post-reaction solids of less than ⅝ inch, defining fine solids (or “fines”), are separated from the balance of thepost-reaction solids 112. Other configurations for separating other sizes of post-reaction solids 112 (i.e., solid matter) can also be defined and used. Thus, typical operation of thescreen process 120 derives a stream (or supply) of relatively coarsepost-reaction solids 122, and a stream (or supply) offine solids 124. - As depicted in
FIG. 1 , thecoarse solids 122 are routed ontoother processing 126, which can include any desirable step or combination of steps for handling the relativelycoarse solids 122. Suchother processing 126 step or steps can include, for example, detoxification and/or disposal of the coarsepost-reaction solids 122, further extraction of another material of interest therefrom, processing and/or market preparation of “cleaned” coal or oil shale (e.g., coal or oil shale from which sulfur has been “washed” or leached within the MFR 110), etc. One of skill in the mining arts is aware of numerous subsequent steps that can be performed after screen separation of fines from coarse solids, and further elaboration is not needed for purposes herein. - The
system 100 ofFIG. 1 further includes acentrifuge process 128. Thecentrifuge process 128 includes any suitable apparatus configured to receive the fine post-reaction solids (fines) 124 and to additionally separate pregnant leach solution (i.e., PLS 114) there from by way of centrifugal force (i.e., rapid rotation within a drum), thus deriving a stream (or supply) ofpregnant leach solution 130. Thepregnant leach solution 130 can be routed if needed to a clarifyingprocess 132, described in detail hereinafter. Also, thecentrifuge process 128 derives a stream (or supply) of generally dried (i.e., “dewatered”)post-reaction solids 136. One of ordinary skill in the mining arts is aware of various suitable centrifuge processes and apparatus, and further elaboration is not required. - The
system 100 also includes a barren solution (or water)wash 140. Typically, thebarren solution wash 140 can be used to leach additional PLS (i.e., PLS 114) out of the (dried, or “dewatered”)fine solids 136. For example, somefine solids 136 include surface geometry, absorption characteristics, or other considerations that economically justify use of thebarren solution wash 140 in order to recover additional material of interest (i.e., cyanide complexed gold, etc.) therefrom. In one embodiment, the barren solution wash is provided by way of a vessel substantially mechanically equivalent to themass flow reactor 110. However defined and used, the barren solution (or water) wash 140 derives a stream (or supply) ofaqueous leachate 142 borne by the (dried) fine solids as they exit thebarren solution wash 140. In a sense, thefine solids 136 have been “rewetted” by way of soaking (leaching) within thebarren solution wash 140 in the interest of recovering additional material of interest therefrom (e.g., dissolved copper, etc.). In some cases, the barren solution orwater wash 140 is not used at all. - The
system 100 also includes anothercentrifuge 144. Thecentrifuge 144 can be defined by any suitable apparatus configured to receive the stream of “rewetted” fine solids from thebarren solution wash 140 and to separate theaqueous leachate 142 therefrom by way of centrifugal force. In this way, thecentrifuge 144 derives a stream (or supply) of liquidaqueous leachate 146 and a stream (or supply) of re-dried (or “dewatered”)fine solids 145. As also depicted inFIG. 1 ,re-dried fines solids 145 are optionally routed ontoother processing 138, which can include any desirable step or combination of steps for handling there-dried fines solids 145. Suchother processing 138 step (or steps) can include, for example, detoxification and/or disposal of there-dried fines 145, further extraction of another material of interest therefrom, cyclonic (or other) separation of different sizes (or classes) offines material 145, etc. One of skill in the mining arts is aware of numerous subsequent steps that can be performed after centrifuge separation of liquid from fines, and further elaboration is not needed for purposes herein. - The
system 100 includes a clarifyingprocess 132. The clarifyingprocess 132 can be defined by, or include, any suitable apparatus or processing step (or steps), if any, as desired or required, to remove solids from or otherwise handle the stream ofpregnant leach solution 130 generated by thecentrifuge process 128, and/or theaqueous leachate 146 generated by thecentrifuge 144. For example, in a case where thePLS 130 contains 5000 ppm solids, reacted lixiviant and material of interest therein (e.g., dissolved copper, etc.), the clarifyingprocess 132 can be suitably defined to remove a substantial fraction of the solids therefrom. In any case, the clarifyingprocess 132 derives a stream (or supply) ofpregnant leach solution 134 to be routed on to thePLS process 116 described above. In another embodiment of the system 100 (not shown), the clarifyingprocess 132 is bypassed or omitted altogether. In yet another embodiment (not shown), the clarifyprocess 132 can be suitably interconnected to theheat exchanger 115 so as to be heated or cooled thereby. - The
system 100 ofFIG. 1 depicts particular system elements (i.e., process apparatus) coupled in particular cooperative relationships. However, it is to be understood that other systems (not shown) can also be defined and used in accordance with various corresponding embodiments. Further exemplary operation of thesystem 100 will be described hereinafter. While thesystem 100 ofFIG. 1 is described above in terms of processing run-of-mine ore (i.e., 102), it is to be understood that another system (not shown), including a mass flow reactor (e.g.,MFR 110, etc.), can also be defined and used for decontaminating soil and the like. One of ordinary skill in the mining or industrial arts and/or geological sciences will recognize that theMFR 110 can provide a basis for any number of substantially continuous processes involving reactions between solid and liquid materials. -
FIG. 2 is a block diagrammatic view depicting selected details of thesystem 100 ofFIG. 1 . As depicted inFIG. 2 , the mass flow reactor (i.e., vessel) 110 is coupled to receive the stream of crushed solids (i.e., crushed ore) 106 directly—that is, theslurry prep tank 107 ofFIG. 1 is not included. Furthermore, themass flow reactor 110 is coupled in fluid communication with the supply oflixiviants 108. As depicted inFIG. 2 , theMFR 110 receives the crushedsolids 106 via at least one point (or opening) 150 proximate an open top of theMFR 110. However, in another embodiment (not shown), theMFR 110 is configured to receive the crushedsolids 106 via at least one point (or opening) elevationally lower with respect to theMFR 110. It is to be understood that thesystem 100 is suitably equipped to regulate the flow of crushedsolids 106 into themass flow reactor 110 over some predetermined range, including complete shut off (zero flow). - The
mass flow reactor 110 is also configured to receive thelixiviant 108 at a plurality of liquid entry points (or openings) 152 elevationally distributed within theMFR 110. While not specifically depicted inFIG. 2 , it is understood that themass flow reactor 110 is suitably equipped (e.g., via valves, pressure regulators, electronic and/or pneumatic controls, etc.) so as to throttle, or regulate, the flow of lixiviant 108 (i.e., liquid) through each of the liquid entry points 152 over some predetermined range, including complete shut off. The flow oflixiviant 108 can be independently controlled through eachliquid entry point 152, suitably ganged so as to throttle eachliquid entry point 152 flow in unison with the others, etc. - The
MFR 110 is also configured to permit the extraction ofpost-reaction solids 112 from one or more solids exit points (or openings) 154. Typically, at least one suchsolids exit point 154 is coincident with, or substantially proximate to, a bottom center “B” as defined by themass flow reactor 110. Other respective suitable locations defined by theMFR 110 can also be used for locating the solids exits points 154. In any event, themass flow reactor 110 is suitably equipped so as to throttle the flow ofpost-reaction solids 112 through each of the solids exit points 154 over some predetermined range, including complete shut off. The flow ofpost-reaction solids 112 can be independently controlled through eachsolids exit point 154, coupled (ganged) so as to throttle eachexit point 156 flow in unison with the others, etc. - The
MFR 110 is further configured to permit the extraction ofpregnant leach solution 114 at a plurality of liquid exit points (or openings) 156 elevationally distributed within theMFR 110. It is to be understood that themass flow reactor 110 is also suitably equipped so as to throttle (regulate) the flow of lixiviant pregnant leach solution 114 (i.e., liquid) through each of the liquid exit points 156 over some predetermined range, including complete shut off. The flow ofPLS 114 can be independently controlled though eachliquid exit point 156, ganged such that eachliquid exit point 156 flow is throttled in unison with the others, etc. - It is important to note that the
mass flow reactor 110 as depicted byFIG. 2 is configured such thatpost-reaction solids 112 and pregnant leach solution 114 (as well as, to some respective extents, crushedsolids 106 and lixiviant 108) are induced to migrate (or flow) thorough theMFR 110 substantially under the influence of gravity alone, in the prevailing direction indicated by the arrow “G”. It is to be further understood, of course, thatpost-reaction solids 112 andpregnant leach solution 114 also migrate toward their respective solids exitpoints 154 and liquid exit points 156, in various directions which deviate from the prevailing direction “G” in order for material (e.g.,PRS 112 and PLS 114) extraction from theMFR 110 to be performed. However, such extraction of thepost-reaction solids 112 and thepregnant leach solution 114 is also performed substantially under the influence of gravity alone. As used herein, “substantially under the influence of gravity alone” refers to migration or motion of respective materials through themass flow reactor 110 without the use of other mechanical driving means or influences—for example, themass flow reactor 110 is devoid of any driven paddles or augers, downward and/or upward liquid jetting, or vibration, shaking, rocking or rotation of theMFR 110, and wherein gravity accounts for not less than ninety percent of the overall migration-inducing force when themass flow reactor 110 is operated with a gaseous pressure (other than ambient atmospheric) present over the liquid and/or solids materials being processed within the MFR 110 (e.g., see location “U” inFIG. 2 ). This makes operation of themass flow reactor 110 distinct from other types of vessels or processing conduits known in mining or the related arts. - The
mass flow reactor 110 ofFIG. 2 is also configured so as to define an internal cavity of volume “V”, and a maximum possible (or working) depth “L” of liquid there in. In this way, it is possible to establish a predetermined hydrostatic head gradient by providing and/or maintaining the corresponding depth “L” of liquid (i.e.,lixiviant 108 and PLS 114) within theMFR 110. In one exemplary embodiment, theMFR 110 is configured such that a stratum corresponding to a hydrostatic head “H” in excess of 65 feet of the liquid is present, and can be maintained, within themass flow reactor 110. Other configurations ofMFR 110 corresponding to other (potential) magnitudes of hydrostatic head can also be used. In any case, themass flow reactor 110 can be suitably configured to provide a zone (or stratum) where at least some of the reaction of the crushedsolids 106 with thelixiviant 108 can take place under a predetermined hydrostatic head “H” of the liquid. As depicted inFIG. 2 , theMFR 110 can be generally open to ambient atmospheric pressure at an elevationally upper end “U”. In another embodiment (not shown), theMFR 110 is configured such that a non-atmospheric pressure (i.e., a relative vacuum or over-atmospheric pressure) is present over the liquid within theMFR 110, wherein such pressure—be it atmospheric or not—can be provided by way of any suitably selected gas (e.g., air, O2, N2, NOx, CO2, etc.). - As depicted in
FIG. 2 , themass flow reactor 110 is coupled in fluid communication with a supply ofgas 158. TheMFR 110 receives thegas 158 by way of at least one gas entry point (or opening) 160. Such gas entry point or points 160 can be selectively located and/or distributed within theMFR 110 as desired or required. Non-limiting examples of thegas 158 include an oxygen/air mixture, a sulfur dioxide/air mixture, air, pure oxygen, a gaseous oxidizing agent, or any of these or another suitable gas or gasses dissolved in a liquid or lixiviant that is injected into thereactor 110 via entry port(s) 160, etc. Othersuitable gases 158 can also be defined and used in. For example, thegas 158 can be an oxygen/air mixture of predetermined ratio that is provided to theMFR 110 for purpose of oxidizing sulfur compounds present within or liberated from the crushedsolids 106 so that such oxidized sulfur compounds are more readily handled at some subsequent process (not shown) external to themass flow reactor 110. Furthermore, themass flow reactor 110 in the upper end “U” (or area proximate thereto) can be suitably equipped with ducting or piping, fume collection hoods, fans, etc. (not shown), so that gases (e.g., thegas 158, a gaseous by-product or by-products of reaction, etc.) can be captured/collected and routed away from theMFR 110 for containment, processing, etc. In any case, one of ordinary skill in the mining arts is aware of numerous processes in which one or more gases can be injected into a reaction zone for one or more purposes, and further elaboration is not required. - The
mass flow reactor 110 ofFIG. 2 can also be coupled to a supply offlocculant 170 that can be controllably introduced into theMFR 110 at one or more flocculant entry points (or openings) 172. Theflocculant 170 can be defined by any suitable agent used to cause relatively fine particles of the crushedsolids 106 to adhere to one another, thus defining a plurality of larger solids entities. In an alternative embodiment, theflocculant 170 is defined by any suitable agent that causes such fine particles of the crushedsolids 106 to adhere to relatively larger particles (or chunks) of the crushed solids 106 (agglomeration). In this way, an overall permeability of the crushedsolids 106 with respect to the lixiviant (liquid) 108 within theMFR 110 can be suitably affected so as to increase contact between the two. In any case, theflocculant 170 can be provided to theMFR 110 when such flocculation or agglomeration is desired. One of ordinary skill in the mining arts is familiar with the selection and use offlocculants 170 as applied to processing ore “fines”, and further elaboration is not required here. - In another embodiment (not shown), a supply of inert solids is provided and selectively used so as to affect and/or stabilize one or more physical characteristics during reaction of solids with liquid(s) within a mass flow reactor (e.g., the
MFR 110, etc.) such as, for example, increasing or decreasing heat conductivity, increasing or decreasing heat absorption, increasing or decreasing heat capacity, etc. Non-limiting examples of such inert solids (not shown) include steel spheres, etc. -
FIG. 3A isflowchart 200 depicting a method in accordance with one embodiment of the present teachings. The method of theflowchart 200 is described hereinafter in reference tosystem 100 ofFIGS. 1 and 2 in the interest of understanding. However, it is to be understood that the method of theflowchart 200 can also be performed using other systems and/or elements (not shown) within the scope of the present teachings. While theflowchart 200 depicts particular method steps and order of execution, it is to be understood that other embodiments that include other respective steps and/or orders of execution can also be used. Thus, the method of theflowchart 200 is exemplary of any number of other such methods within the present scope. - In step 202 (
FIG. 3A ), run-of-mine ore is crushed to a suitable median size. For purposes of example, it is assumed that gold-bearing, run-of-mine ore 102 (FIG. 1 ) is crushed using asuitable crusher 104 so as to derive (define) crushed solids (i.e., crushed ore) 106 having a median size of approximately 0.375 inches in diameter. Other median sizes and/or sizing schemes for the crushedsolids 106 can also be used. - In step 204 (
FIG. 3A ), crushed solids 106 (FIG. 2 ) are provided directly into themass flow reactor 110 by way ofsolids entry point 150 so as to fill theMFR 110 to a predetermined operating depth (i.e., vertical pile dimension) “S”. Thus, the slurry prep tank 107 (FIG. 1 ) is assumed to be bypassed or otherwise unused. For purposes of the ongoing example, it is assumed that theMFR 110 is filed with crushedsolids 106 to a depth “S” of eighty feet. Other operating depths of the crushedsolids 106 within theMFR 110 can also be used. It is further assumed that the cavity volume “V” defined by themass flow reactor 110 is such that 82,700 tons of crushedsolids 106 are present when the exemplary depth “S” of eighty feet is achieved. It is important to note that at this time, no material is being extracted from theMFR 110. Once the desired depth “S” of crushedsolids 106 is established in theMFR 110, the flow thereof is ceased at least for the time being. Also at this time or anytime while filling, any initial amount offlocculant 160 that is desired can be provided into theMFR 110. - In step 206 (
FIG. 3A ), a predetermined liquid lixiviant 108 (FIG. 2 ) is provided into themass flow reactor 110 by way of controlled flow through one or more of the liquid entry points 152. For purposes of example, it is assumed that a predetermined operating depth “L” of ninety feet of the lixiviant 108 (i.e., liquid) is established in theMFR 110. Other operating depths “L” can also be used. It is further assumed that thelixiviant 108 is defined by an aqueous solution including cyanide. As in step 204 (FIG. 3A ) above, no material is being extracted from the MFR 110 (FIG. 2 ) at this time. Once the desired liquid depth “L” oflixiviant 108 is established in theMFR 110, the flow thereof is ceased for the time being. - In step 208 (
FIG. 3A ), the crushed solids 106 (FIG. 2 ) are reacted with thelixiviant 108 within theMFR 110 for a predetermined period of time, or dwell, so as to permit at least one material of interest to be dissolved out of the crushedsolids 106 and into solution with thelixiviant 108. Thus, the derivation ofpost-reaction solids 112 andpregnant leach solution 114 is underway. Also, if desired or required, thegas 158 can be controllably introduced into themass flow reactor 110. This dwell time (i.e., period of reaction without any extraction ofpost-reactions solids 112 or pregnant leach solution 114) can be performed for any predetermined period of time such as, for purposes of example, five hours, etc. - In step 210 (
FIG. 3A ), the post-reaction solids 112 (FIG. 2 ) and the pregnant leach solution 114 (as well as substantially not-yet-reactedlixiviant 108 and crushed solids 106) begin to migrate through themass flow reactor 110 in the prevailing direction “G”, by way of gravity alone. In this initial instance, such migration is generally due to settling of material due to the liquid-bath conditions present in theMFR 110. - In step 212 (
FIG. 3A ), which in fact can occur just prior to, or almost simultaneously with,step 210 above, the extraction of post-reaction solids 112 (FIG. 2 ) via one or more of the solids exitspoints 154 begins. The extraction ofpregnant leach solution 114 by way of one or more of the liquid exit points 156 is also begun. The extraction of thepost-reaction solids 112 is generally performed in a controlled fashion so that the volumetric (or mass) flow of thepost-reaction solids 112 follows a predetermined pattern or scheme, defining a solids extraction flow rate. In turn, the extraction ofpregnant leach solution 114 is also performed in a predetermined controlled-flow manner, defining a liquid extraction flow rate. Such solids and liquids extraction flow rates can be, respectively, substantially constant, increase or decrease linearly or non-linearly over time, etc. In short, any desired flow rate characteristic can be independently employed in regard to the extraction ofpost-reaction solids 112, and any desired flow rate characteristic can be employed, up to the maximum permeability rate, in regard to the extraction ofpregnant leach solution 114. In any case, the extraction ofPRS 112 andPLS 114 is performed substantially under the influence of gravity alone as previously described above. - Also in step 212 (
FIG. 3A ), the introduction (or addition) of crushed solids 106 (FIG. 2 ) into theMFR 110 is performed at a rate in accordance with the extraction ofpost-reaction solids 112. Furthermore,lixiviant 108 is added to theMFR 110 at a rate corresponding to the extraction ofpregnant leach solution 114. Thus, at this time, crushedsolids 106 are added to, andpost-reaction solids 112 are extracted from, themass flow reactor 110 in a simultaneous fashion such that a “mass flow” or migration (substantially under the influence of gravity alone) of solid material through theMFR 110 is established and maintained for a predetermined period of time. For purposes of the ongoing example, this simultaneous flow of crushedsolids 106 andpost-reaction solids 112 is maintained for a period of at least of at least 3 days. Typically, the crushedsolids 106 and thepost-reaction solids 112 are extracted at substantially equal and/or constant rates, such that the predetermined depth “S” of solids (e.g., eighty feet, etc.) within theMFR 110 is generally maintained constant during this “simultaneous flow” period. Furthermore,lixiviant 108 is added to, and pregnant leach solution 114 (as well as any trace and/or incidental amount of PLS borne by the PRS 112) is extracted from, theMFR 110 in a simultaneous fashion, such that a gravity-driven mass flow or migration of liquid material through theMFR 110 is established and maintained for a period of time. For purposes of the ongoing example, this simultaneous flow oflixiviant 108 and pregnant leach solution 114 (as well as any residual amount of PLS borne by the PRS 112) is maintained for a period of at least 3 days. Generally, the respective flow rates of thelixiviant 108 and thepregnant leach solution 114 are controlled at substantially equal and/or constant rates, such that the predetermined liquid depth “L” (e.g., ninety feet, etc.) is maintained essentially constant within theMFR 110 during the time of simultaneous flows. - It is important to note that the respectively controlled flow rates of solids (i.e., crushed
solids 106 and PRS 112) and liquids (i.e.,lixiviant 108 and PLS 114) through themass flow reactor 110 results in the reacting, or processing, of ore or other solid materials in a manner that is substantially continuous—rather than batch-like—in overall process operation. This means that once the desired depths (i.e., quantities) of solids “S” and liquid “L” are established in the MFR 110 (e.g., as insteps mass flow reactor 110, if desired, by way of appropriate solids and liquid flow control in to and out of (that is, through) theMFR 110. Once established, such continuous processing can be perpetuated for essentially any predetermined period of time (hours, days, weeks, months, etc.). - In step 214 (
FIG. 3B ), the post-reaction solids 112 (FIG. 1 ) are routed to ascreen process 120. Therein,post-reaction solids 112 of less than a predetermined size are separated from the balance of thepost-reaction solids 112, thus defining a stream (or supply) of relatively coarsepost-reaction solids 122, and a stream (or supply) of fine post-reactions solids (or “fines”) 124. For purposes of example, it is assumed that thescreen process 120 is defined and provided such that thefines 124 are comprised of individual particles less than five-eights inch in size. Other sizing (or classifying) schemes can also be used in separatingfines 124 from coarsepost-reaction solids 122. The coarse post-reaction solids 122 (FIG. 1 ) are then routed to suitableother processing 126 such as, for example, detoxification, disposal, heaping for later processing, etc. - In step 216 (
FIG. 3B ), the stream of fine post-reactions solids 124 (FIG. 1 ) are received by acentrifuge process 128 where additional pregnant leach solution (i.e., PLS 114) is extracted from thefines 124 resulting in a stream (or supply) ofpregnant leach solution 130. In another embodiment, (not shown), other equipment such as filters could be used instead of thecentrifuge process 128. Fine post-reaction solids exit thecentrifuge process 128 and define a stream (or supply) of driedfines 136. While such are referred to as “dried”, it is to be understood that relatively small quantities ofPLS 114 may still be present on, or absorbed within, the driedfines 136. This aspect of the driedfines 136 will be considered in further detail below. - In step 218 (
FIG. 3B ), the stream of pregnant leach solution 130 (FIG. 1 ) is received by a clarifyingprocess 132. The clarifyingprocess 132 removes solids from thePLS 130, by a gravity type clarifier, a cyclonic type clarifier, by filters, or by any suitable known means, so as to derive a relatively low-solids stream (or supply) ofpregnant leach solution 134. In this way,subsequent PLS 134 processing can be performed with greater efficiency and/or efficacy as most of the solids in the solution have been removed. In some embodiments, the clarifyingprocess 132 is omitted altogether, and the stream (or supply) ofPLS 130 directly defines the stream (or supply) ofPLS 134 by way of, for example, carbon columns treating dilute gold solutions. - In step 220 (
FIG. 3B ), the dried fines 136 (FIG. 1 ) are (optionally) routed to a barren solution (or water)wash 140. Thebarren solution wash 140 is essentially a barren solution filled vessel in which the driedfines 136 are soaked for some period of time so as to further extract (i.e., leach) relatively small or trace amounts of pregnant leach solution (i.e., PLS 114) from the driedfines 136. Typically, thebarren solution wash 140 is used only when the material of interest (i.e., gold, platinum, etc.) dissolved into the pregnant leach solution (i.e., PLS 114) is of sufficient value to economically warrant such extra processing. When used, thebarren solution wash 140 derives a stream (or supply) ofaqueous leachate 142 borne by the “rewetted” fine solids. For purposes of ongoing example, it is assumed that at least some of the driedfines 136 are routed to thebarren solution wash 140, where additional gold-bearingpregnant leach solution 114 is leached out of the driedfines 136 and into solution with the barren solution, thus defining theaqueous leachate 142. It is also assumed that the fines bearing theaqueous leachate 142 are routed toother processing 138, where theaqueous leachate 142 is separated from the fines (e.g., by way ofcentrifugal separation 144, a filter arrangement (not shown), etc.) and thereafter combined with thePLS stream 134 for additional processing atstep 222 below. In turn, it is further assumed that any non-washedfine solids 136 are sent to respectiveother processing 138 and are discarded, etc. In those embodiments (not shown inFIG. 3B ) where thebarren solution wash 140 is not used, the driedfines 136 are simply routed toother processing 138 for detoxification, disposal, etc., as desired. - In step 222 (
FIG. 3C ), the respective streams (or supplies) of pregnant leach solution 114 (FIG. 1 ) and 134 are received at a pregnantleach solution process 116. Thus, with respect to thePLS stream 114, the heat exchanger 115 (FIG. 1 ) is assumed to be bypassed or otherwise unused. Therein, any suitable process step or combination of steps and/or apparatus is/are used to extract at least a majority of the material of interest from the aggregate pregnant leach solution (114 and 134 ofFIG. 1 ). For purposes of ongoing example, it is assumed that dissolved gold is recovered from the aggregate PLS by way of adsorption, elution, electrowinning and retorting—processes known to one of ordinary skill in the mining engineering arts. The recovered material of interest (e.g., gold, etc.) is then sent on to step 224 (FIG. 3C ) below. The residual liquid of processing the pregnant leach solution (114 and 134 ofFIG. 1 ) is assumed to be processed as desired by way of regeneration, destruction, containment and disposal, etc. - In step 224 (
FIG. 3C ), the recovered material of interest fromstep 222 above is finally processed as needed so as to be delivered to the market place. For purposes of example, it is assumed that retorted gold is smelted by known techniques to produce gold bullion. Other process steps can also be employed, as needed or desired, in accordance with the goal at hand. In this way, thesteps 222 and/or 224 are typically performed so as to isolate at least one material of interest, as originally present in the run-of-mine ore 102 (FIG. 1 ), in a form that can be provided to (i.e., sold within) the market. At this point, the exemplary method of theflowchart 200 is presumed to be completely described. - In the interest of understanding, at least some of the characteristics and advantages of the present teachings are summarized as follows:
- a) The reaction of crushed solids with lixiviant (or other liquid) can be performed within a vessel, otherwise referred to as a mass flow reactor, as a substantially continuous process;
- b) Solid and liquid materials migrate through, and are extracted from, a mass flow reactor substantially under the influence of gravity alone and without the use of other relevant mechanical means or forces such as, for example, driven paddles, augers, downward and/or upward liquid jetting, or vibrating, rocking, shaking, and/or rotating the mass flow reactor, and wherein gravity is not less than ninety percent of the migration-inducing force when gaseous pressure is present over the materials within the mass flow reactor;
- c) At least some of the reaction of crushed solids with liquid within a mass flow reactor can be performed under conditions of a predetermined hydrostatic head of the liquid;
- d) A flocculant can be used, if desired, to affect the permeability of crushed solids with respect to liquid within a mass flow reactor. In this way, liquid-on-solid contact, and the corresponding reaction between solids and liquids, can be suitably increased;
- e) A gas can be injected into a mass flow reactor so as to oxidize or otherwise chemically affect compounds present during the reaction of crushed solids with liquid.
- f) One or more physical and/or chemical variables can be suitably controlled within the mass flow reactor during processing, by any respectively suitable known means. Non-limiting examples of such variables include pH, Eh (i.e., electron potential in solution), temperature, viscosity, the concentration of a gas, the concentration of a liquid, etc.
- g) A suitable inert solid can be used, if desired, to affect—increase, decrease or stabilize—one or more characteristics within a mass flow reactor during a reaction between solids and a liquid or liquids. Non-limiting examples of such characteristics include heat conductivity, heat absorption, etc.
- It is anticipated that the invention will be embodied in other specific forms, not specifically described, that do not depart from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive, the scope of the invention being defined by the appended claims and equivalents thereof.
Claims (45)
1. A method of processing solids with a liquid, comprising:
providing a vessel;
crushing the solids to not less than a predetermined median particle size, thus defining crushed solids;
reacting the crushed solids with the liquid within the vessel, thus deriving a pregnant leach solution and post-reaction solids, wherein at least some of the reacting occurs under a predetermined hydrostatic head;
migrating the pregnant leach solution and the post-reaction solids through the vessel substantially under the influence of gravity alone; and
extracting the pregnant leach solution and the post-reaction solids from the vessel.
2. The method of claim 1 , wherein the crushed solids define a permeability with respect to the liquid within the vessel, the method further comprising:
controlling the permeability by way of at least one of:
chemically flocculating fine particles of the crushed solids to form larger particles of the crushed solids within the vessel;
agglomerating fine particles of the crushed solids to larger particles of the crushed solids prior to the reacting within the vessel; or
removing fine particles of the crushed solids by way of at least one of dry screening, wet screening, or cyclonic separation of the crushed solids prior to the reacting within the vessel.
3. The method of claim 1 , wherein the predetermined hydrostatic head is not less than 65 feet of the liquid.
4. The method of claim 1 , wherein the reacting includes leaching at least one material out of the crushed solids and into solution with the liquid, thus deriving the pregnant leach solution and the post-reaction solids.
5. The method of claim 4 , wherein the at least one material leached out of the crushed solids includes gold, silver, a platinum group metal, gallium, germanium, lead, copper, zinc, uranium, cobalt, nickel, a refractory metal, molybdenum, a light metal, sulfur, crude oil, caregens, or a rare earth element.
6. The method of claim 1 , wherein the liquid includes an aqueous solution of acid or acids, an aqueous solution of acid or acids including an oxidizing agent, sulfuric acid, a solution including sulfuric acid, an aqueous solution of an alkali or alkali's, an aqueous solution of an alkali or alkalis including an oxidizing agent, an aqueous solution of cyanide including an oxidizing agent, an aqueous solution of sodium or calcium hypochlorite, an aqueous solution of ferrous or ferric sulfate, an aqueous solution of ferrous or ferric sulfate including an oxidizing agent, an aqueous solution including a bacterial catalyst, an aqueous solution of chlorine, an aqueous solution of hydrogen peroxide, a solution of ammonium thiosulfate, or an aqueous solution of air and sulfur dioxide and copper.
7. The method of claim 1 , wherein the solids include one of gold-bearing ore, silver-bearing ore, ore bearing at least one platinum group metal, ore bearing rare earth elements, ore bearing gallium, ore bearing germanium, ore bearing light metals, ore bearing copper, ore bearing zinc, ore bearing molybdenum, ore bearing lead, ore bearing uranium, ore bearing cobalt, ore bearing nickel, ore bearing refractory metal, contaminated soil, solids containing coal, solids containing oil sands, and solids containing oil shales.
8. The method of claim 1 , and further comprising adding the liquid into the vessel at a first flow rate, wherein the pregnant leach solution is extracted from the vessel at a second flow rate, and wherein the adding the liquid and the extracting the pregnant leach solution are performed simultaneously for a predetermined period of time.
9. The method of claim 8 , wherein the first and second flow rates are at least one of essentially equal or essentially constant for the predetermined period of time.
10. The method of claim 8 , wherein the predetermined period of time is not less than 3 hours.
11. The method of claim 1 , and further comprising adding the crushed solids into the vessel at a first flow rate, wherein the post-reaction solids are extracted from the vessel at a second flow rate, and wherein the adding the crushed solids and the extracting the post-reaction solids are performed simultaneously for a predetermined period of time.
12. The method of claim 11 , wherein the first and second flow rates are at least one of essentially equal or essentially constant for at least the predetermined period of time.
13. The method of claim 11 , wherein the predetermined period of time is not less than 3 hours.
14. The method of claim 1 , wherein the post-reaction solids are extracted from the vessel proximate a bottom of the vessel.
15. The method of claim 1 , wherein the post-reaction solids are extracted from the vessel substantially under the influence of gravity alone.
16. The method of claim 1 , wherein the pregnant leach solution is extracted from the vessel substantially under the influence of gravity alone.
17. The method of claim 1 , and further comprising separating at least some of the post-reaction solids into at least two distinct groups, wherein each group corresponds to a predetermined median particle size of post-reaction solid.
18. The method of claim 1 , and further comprising removing pregnant leach solution from at least some of the post-reaction solids.
19. The method of claim 18 , including centrifuging at least some of the post-reaction solids to remove at least some of the pregnant leach solution.
20. The method of claim 18 , including passing at least some of the post-reaction solids along a screen to remove at least some of the pregnant leach solution.
21. The method of claim 18 , including leaching at least some of the post-reaction solids in a barren solution wash, thus deriving an aqueous leachate.
22. The method of claim 21 , wherein the vessel is a first vessel, the method further comprising:
providing a second vessel;
performing the leaching of at least some of the post-reaction solids in the barren solution wash within the second vessel, thus deriving the aqueous leachate and post-leaching solids; and
extracting the aqueous leachate and the post-leaching solids from the second vessel.
23. The method of claim 1 , and further comprising extracting at least one material from the pregnant leach solution.
24. The method of claim 23 , wherein the at least one material includes gold, silver, a platinum group metal, gallium, germanium, molybdenum, lead, copper, zinc, uranium, cobalt, nickel, a refractory metal, a light metal, crude oil, sulfur, or a rare earth element.
25. The method of claim 23 , wherein the extracting includes at least one of using a solvent extraction , chemical precipitation, or electrolytic precipitation.
26. The method of claim 1 , and further comprising controlling at least one of pH, Eh, temperature, a gas concentration, or a liquid concentration within the vessel during the reacting the crushed solids with the liquid.
27. The method of claim 1 , wherein the vessel is a first vessel and the liquid is a first liquid and the pregnant leach solution is a first leach solution and the post-reaction solids are first post-reaction solids, the method further comprising:
providing a second vessel; and
reacting at least some of the post-reaction solids with a second liquid within the second vessel, thus deriving a second pregnant leach solution and second post-reaction solids.
28. The method of claim 1 , and further comprising injecting a gas into the vessel during at least some of the reacting the crushed solids with the liquid.
29. The method of claim 28 , wherein the gas is defined by an oxidizing gas.
30. The method of claim 1 , wherein the crushed solids within the vessel define a permeability with respect to the liquid, the method further comprising:
providing at least one essentially inert solid within the vessel during the reacting so as to increase the permeability of the crushed solids with respect to the liquid.
31. A method of processing mine ore with a lixiviant, comprising:
providing a reaction vessel defining solids outlet openings and liquid outlet openings;
crushing the mine ore to not greater than a predetermined size, thus defining crushed ore;
reacting the crushed ore with the lixiviant within the reaction vessel, thus deriving a pregnant leach solution and post-reaction solids;
extracting at least some of the pregnant leach solution from the reaction vessel via the liquid outlet openings substantially under the influence of gravity alone; and
extracting the post-reaction solids and at least some of the pregnant leach solution from the reaction vessel via the solids outlet openings substantially under the influence of gravity alone.
32. The method of claim 31 , wherein the predetermined size is such that at least 80 percent of the crushed ore is not greater than 6 inches in size.
33. The method of claim 31 , and further comprising removing solids of less than 0.15 millimeters from the crushed ore prior to the reacting the crushed ore with the lixiviant within the reaction vessel, the removed solids defining fine solids.
34. The method of claim 33 , and further comprising removing at least one material from the fine solids by way of leaching the fine solids.
35. The method of claim 31 , wherein:
the reacting includes dissolving at least one material out of the crushed ore and into solution with the lixiviant, thus deriving the pregnant leach solution; and
the at least one material includes gold, silver, a platinum group metal, gallium, lead, germanium, copper, molybdenum, zinc, uranium, cobalt, nickel, a refractory metal, a light metal, sulfur, crude oil, or a rare earth element.
36. The method of claim 31 , wherein the lixiviant includes an aqueous solution of acid or acids, an aqueous solution of acid or acids including an oxidizing agent, sulfuric acid, a solution including sulfuric acid, an aqueous solution of a base or bases, an aqueous solution of a base or bases including an oxidizing agent, an aqueous solution of cyanide including an oxidizing agent, an aqueous solution of sodium or calcium hypochlorite, an aqueous solution of ferrous or ferric sulfate, an aqueous solution of ferrous or ferric sulfate including an oxidizing agent, an aqueous solution including a bacterial catalyst, an aqueous solution of chlorine, an aqueous solution of hydrogen peroxide, a solution of ammonium thiosulfate, a lixiviant for leaching uranium, or an aqueous solution of air and sulfur dioxide and copper.
37. The method of claim 31 , wherein the crushed ore includes gold-bearing ore, silver-bearing ore, ore bearing at least one platinum group metal, ore bearing rare earth elements, ore bearing gallium, ore bearing germanium, ore bearing light metals, ore bearing copper, ore bearing zinc, ore bearing molybdenum, ore bearing lead, ore bearing uranium, ore bearing cobalt, ore bearing nickel, ore bearing refractory metals, solids containing coal, solids containing oil sands, or solids containing oil shales.
38. The method of claim 31 , and further comprising introducing the lixiviant into the reaction vessel at a first flow rate, wherein the pregnant leach solution is extracted from the reaction vessel at a second flow rate, and wherein the first and second flow rates are simultaneous.
39. The method of claim 38 , wherein the first and second flow rates are essentially equal, essentially constant, or essentially equal and constant.
40. The method of claim 31 , and further comprising introducing the crushed ore into the reaction vessel at a first flow rate, wherein the post-reaction solids are extracted from the reaction vessel at a second flow rate, and wherein the first and second flow rates are simultaneous.
41. The method of claim 40 , wherein the first and second flow rates are essentially equal, essentially constant, or essentially equal and constant.
42. The method of claim 31 , and further comprising separating at least two predetermined sizes of solids from at least some of the post-reaction solids.
43. The method of claim 31 , and further comprising removing pregnant leach solution from at least some of the post-reaction solids, wherein the removing the pregnant leach solution includes at least one of:
centrifuging at least some of the post-reaction solids;
passing at least some of the post-reaction solids through a filter;
passing at least some of the post-reaction solids along a screen; or
leaching at least some of the post-reaction solids in barren solution wash, thus deriving an aqueous leachate.
44. The method of claim 31 , and further comprising separating at least one dissolved material out of the pregnant leach solution, wherein the at least one dissolved material includes gold, silver, a platinum group metal, gallium, germanium, copper, zinc, uranium, cobalt, molybdenum, nickel, lead, a refractory metal, a light metal, crude oil, caregens, or a rare earth element.
45. The method of claim 31 , and further comprising controlling at least one of temperature, pH, Eh, a gas concentration, or liquid concentration, within the reaction vessel during the reacting the crushed ore with the lixiviant.
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