US3869360A

US3869360A - Reduction method for separating metal values from ocean floor nodule ore

Info

Publication number: US3869360A
Application number: US310604A
Authority: US
Inventors: William S Kane; Paul H Cardwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-05-08
Filing date: 1972-11-29
Publication date: 1975-03-04
Anticipated expiration: 1992-03-04

Abstract

This invention provides a process for obtaining the metal values from ocean floor nodule ore. The ore comprises primarily oxides of iron and manganese plus nickel, copper and cobalt compounds. The ore is treated with an acidic reagent, e.g., sulfur dioxide in the presence of oxygen, to form the water-soluble sulfates of manganese, nickel, copper and cobalt. The reacted ore is leached with water and the resultant leach solution is treated by liquid ion exchange processes to form separate solutions of each of nickel, copper, cobalt and manganese salts. These salts can then be cathodically reduced to form the respective metals.

Description

ijnite ttes Kane et a1.

[ 1 Mar. 4, 1975 i 1 REDUCTION METHOD FOR SEPARATING 3,100,700 8/1963 Hill 75/101 R TA VALUES FROM OCEAN FLOOR 3,728,105 4/1973 Skarbo 75/119 z g gj ORE 3,753,680 8/1973 Wilder et a1. 75/119 3,788,841 12/1973 Agarwal et a] 75/119 [76] Inventors; 3,795,596 3/1974 Kane et al. 204/105 XM 23184; Paul H. Cardwell, Zanoni,

I Va. 23191 Primary Examiner-John H. Mack v Assistant Examiner-R. L. Andrews F 7 1 [22] fled Nov l9 2, Attorney, Agent, or FirmL1ll1ng & Siegel; Barry G. [21] Appl. No.: 310,604 Magidoff Related [1.8. Application Data [63] Continuation-impart of Ser. No. 251,089, May 8, [57] ABSTRACT lg s l gg gy giz g This invention provides a process for obtaining the y o 7 metal values from ocean floor nodule ore.- The ore [52] U S Cl 204/105 R 0 R 204/108 comprises primarily oxides ofiron and manganese plus 75/l15 75/1 17 75/1I9 75/12l nickel, copper and cobalt compounds. The ore is 75nd BE 5 R dtreated with an acidic reagent, e.g., sulfur dioxide in [51] Int Cl (322d U24 C22d 1H4 C22d 1H6 the presence of oxygen, to form the water-soluble sul- [58] Fie'ld 'gg HIS/1 l 117 121 fates of manganese, nickel, copper and cobalt. The re- 75/1Ol. R 'gj' 6 acted ore is leached with water and the resultant leach 5 solution is treated by liquid ion exchange processes to form separate solutions of each of nickel, copper, co bait and manganese salts. These salts can then be ca- [561 UN E S S S thodically reduced to form the respective metals. 2,775,517 1/1957 Mancke ..'75/11'9 Claims, 2 Drawing Figures NODULES 02 AQUEOUS lj LEACH /A\ I LEACH TANK AIR K FILTER- F8203,

C0504 1 HCL LIE FT l STRIP Cu Cu I I non STRIP EXT. I LIE P Ni Co In 1 i Co p Co Ni "2 4 EXT; TANK EXT 42 STRIP pH J M Co n STRIP; Mn m pm CELL CELL l l l Q Co METAL Cu METAL Mn METAL Ni METAL PATENTEUHAR 41975 L 3.869.360

SHEET 1 M2 NODULES CRUSHEH l v LEACH EAL TANK AIR K FILTER V Fe O 2 s cuso' T 4 HCL LIE I L r Y STRIP CO V Cu Cu Q TIOA- STRIP ExT. LIE v T PH NiCo. L f-UE L T 00 Co l?g+ EXT. 5 STRIP 1 PH Q C0 Mn T 1 STR!P 0 CELL Mn Hi T, I U CELL cELL L I l l Y g --1-c METAL Cu METAL Mn METAL Ni METAL E REDUCTION METHOD EORfiEPARATING METAL VALUES F ROM OCEAN FLOOR NODULE ORE This is a continuation-in-part of a copending U.S.

Pat. application Ser. No. 251089 filed on May 8, 1972,

which in turn is a continuation of U.S. application Ser.

No. 40,586 filed May 26, 1970, both now abandoned.

It is not a common situation to obtain a relatively valuable nonferrous metal such as nickel, cobalt, copper, manganese, titanium, indium and zinc, from minerals which are primarily iron ores, i.e., containing a relatively high proportion of iron. A relatively untapped source of a high-quality manganiferous ore, however, is a material which is found on the ocean floor and has come to be known as ocean floor nodule ore.

With the increased awareness on the part of both the public and the metals industry of the ecological dangers that can arise from continued surface mining of minerals and the increased problems of pollution caused by the refining procedures required for most ores mined from the land, industry has been interested for several years now in the mining of minerals from the sea. This has been an extremely elusive target up to the present. The directions taken have included both attempts to wrest minerals directly from solution in sea water and the mining of ores which are available on the floor of the ocean. These ores do not require any digging into or stripping of the earths crust; the ocean floor ores can merely, be scooped up or in other ways removed from the ocean floor without actually rending the earths surface.

Ocean floor nodules were first collected in the first half of the 1870s. They have been studied by many I workers in an attempt to determine their composition,

and after their composition had been determined to try to be a direct result of the conditions under which they were created and to which they have been exposed since their creation. First, the nodules have never been exposed to temperatures other than those at the bottom of the ocean at the location at which'they were formed. They have an extremely large surface area, often better than percent porosity and they are thus relatively chemically reactive ores.

The nodules are formed as an extremely complex crystal matrix of iron and manganese oxides: tiny grains of each oxide of a size and type which are substantially impossible to separate with present available physical means. These iron and manganese oxides form the crystalline structure within which are held, by means not precisely known, other metal compounds, most likely oxides, including those of nickel, copper and cobalt, as the main ingredients, followed by chromium, zinc, tin, vanadium, and many more elements, including the rare metals silver and gold.

In addition to the crystals of compounds ofthe valuable metals present, there is also a large quantity of silt. or gangue material intimately admixed in the nodule ore. This silt, or gangue, is sand and clay, and includes the usualoxides of silicon and aluminum in varying proportions and some carbonates, especially calcium carbonate.

The precise chemical composition of the nodules varies depending upon their location in the ocean. The variation apparently is caused by differences in temperature in various places, differences in composition of sea water perhaps caused by the pressure and temperature variations at different depths and composition of adjacent land areas, variations in the amount of oxygen which is present in the water in different locations and perhaps other variables not readily apparent to observers. Generally, however, in almost all cases the metals which are present in primary proportions are manganese and iron. The following table (taken from an article entitled The Geochemistry of Manganese Nodules and Associated Deposits from the Pacific and Indian Oceans" by Croonan and Tooms in Deep Sea Research (1969), Volume l6,.pages 335-359, Pergamon Press (Great Britain) shows the relative compositions of the most valuable metals contained in nodules taken from different areas within the Pacific and Indian Oceans.

Table I Mn 13.95 16.87 15.71 15.85 22.33 19.81 16.61 13.56 15.83 Fe 13.10 13.30 9.06 12.22 9.44 10.20 13.92 16.75 11.31 N1 0393 0.564 0.956 0.348 1.080 0.961 0.433 0.322 0.512 C0 1.127 0.395 0.213 0.514 0.192 0.164 0.595 0.358 0.153 Cu 0.061 0.393 0.711 0.077 0.627 0.311 0.185- 0.102 0.330 Pb 0.174 0.034 0.049 0.035 0.028 0.030 0.073 0.061 0.034 Ba 0.274 0.152 0.155 0.306 0.38l 0.145 0.230 0.146 0.155 M0 0.042 0.037 0.041 0.040 0.047 0.037 0.035 0.029 0.031 v 0.054 0.04.4 0.036 0055v 0041 0.031 2 0.050 0.051 0.040 Cr 0.0011 0.0007 0.0012 0.0051 0.0007 0.0005 0.0007 0.0020 0.0009 Ti 0773 0.810 0.561 0.489 0.425 0.467 1.007 0.820 0.582 1 .0.1 30.87 25.50 22.12 24.78 24.75 27.21 28.73 25.89 27.18

ept (in) v 1757 5001 5049 1146 4537 4324 3539 3793 5046 Mid-Pacific Mountains (6 samples) West Pacific (23 samples) Central Pacific (9 samples) Southern Borderland Seamount Province (5 samples) Northeast Pacific (l0 samples) Southeast Pacific (8 samples) South Pacific (I 1 samples) West lndian Ocean (10 samples) East Indian Ocean (14 samples) Nodules are also found in the Atlantic Ocean; how- I ever, it has been found thatgenerally these nodules contain lower amounts of the more valuable metals and correspondingly high amounts of the less desirable metals which cannot be readily refined and which have little or no value; such as the alkaline earth metals.

Because of the peculiar and intricate crystal structure of the ocean floor nodules, the common refining techniques used for the refining of land ores are not generally suitable for the nodules.

Mero in U.S. Pat No. 3,169,856 discloses a scheme for separating the nickel from the cobalt in ocean floor ore deposits. The Mero process is directed to a specific type of ocean floor nodule ore wherein the separate mineral phases of manganese and iron contain different metal constituents;Specifically, according to Mero nickel and copper are presentonly in the manganese phase of the material whereas cobalt is present solely in the iron-phase. Mero further states that the'oxides are in solid solution within the nodule. Mero reacts the nodule strong reducing agent for example, S or The Mero process is-based upon the unique relationship of the metal constituents in being sub-divided beas a result of the phase differences in the nodule ores, it is possible to carry out a process for differentially leaching these materials from the ore. In a first stage,

the ore is contacted with an aqueous solution comprising 50;, or N0 to selectively leach out manganese, nickel, copper and other mineral elements bound up in the manganese phase of the ore. The cobalt and ironare not leached out. The first solution containing the manganese, nickel and other'elements is then treated by various chemical means to' separate the different metal values.

S chaufelberger, in U.S. Pat. No. 2,778,729, discloses a process for the recovery of nickel and cobalt from land-based garnierite ores, i.e., ores containing metal values in a structure of magnesium silicate minerals. Such minerals contain as the valuable metal constituents manganese, copper, cobalt, nickel and iron. Aqueous slurries of the crushed minerals are treated with S0 gas. A major problem with refining of these ores is involved in the removal of the magnesium silicate which is a-major constituent of these ores.

ln accordance with the present invention an improved novel process is provided for extracting individual metal values from an ocean floor nodule ore. The process com prises: (l) reacting, in'the presence of oxygen, the nodule ore with an acidic reducing agent, such as sulfur dioxide, which'is capable of reacting with the metal values in the ore to form as reaction products the corresponding water-soluble Salts, e.g., the sulfates, of divalent manganese, nickel, cobalt and copper, (2)

contacting the metal values with sufficient oxygen to, convert substantially all of the iron to iron oxide; (3) leaching the reacted ore with water to form an aqueous pregnant leach solution comprising the water-soluble salts of divalent manganese, copper, nickel and cobalt; (4) separating the pregnant leach solution from anyinsoluble residue; (5) contacting the aqueous solution with a liquid ion exchange agent to separate out an individual metal value and to form a solution of the individual metal value in the form of a water-soluble salt;

' tween the manganese and iron phases. Mero states that tion of the water-soluble salt.

and (6.) reducing the metal value to the elemental metal by cathodi-cally electrodepositing from the solu- Steps (1), (2) and (3) above, are preferably carried out simultaneously by reacting the nodule-ore with the acid-reducing agent in the presence of excess oxygen in an aqueous medium, e.g., a bath of an aqueous solution. For example, the ore can be comminuted and slurried in water and S0 with excess oxygen, can be bubbled therethrough, or a concentrated aqueous solution of S0 can be contacted with the comminuted ore with excess oxygen. Alternatively, the ore can first be contacted with SO gas plus'oxygen, and then leached with water, preferably with additional oxygen being bubbled through the leach water.

The process of the present invention successfully and completely breaks up the matrix of the manganese oxide-iron oxided crystal structure in the nodule ore, freeing the valuable nonferrous metals from the ore in the form of soluble salts. The first steps of the process of of the solution, are most generally utilized. Ambient pressures and temperatures are most preferred. The speed of the reaction, which is a first order reaction, is such that higher temperatures would not be of any advantage. The costs of heating the reaction mixture can a temperature of from about 40 to about 500C. is I useful, preferably from about 20 to about 4,00C. and

optimally up to about C. In both types of reaction, 7

gaseous or aqueous medium, ambient conditions are most useful. when operating a large bed of ore on a commercial scale, cooling may be required. The reaction is first order and highly exothermic; it can be initiated at ambient or even lower temperatures. The maximum permissible temperature is a function-of the reaction equipment and not limited substantially bythe reaction.

The aq u e ous solution of the manganese, copper, cobalt and nickel salts whiclTis produced during this process is preferably substantially free of iron. this is gen- 'erally desirable when the metal values are to be separated by liquid ion exchange. The production of an iron-free solution is accomplished, generically, by maintaining the iron as the insoluble oxide or by converting any soluble iron sulfate formed to the insoluble oxide.

When treating bonedry nodule ore with SO in an an hydrous system, the iron is not converted to a'soluble compound. The following reaction equations are believed to apply:

The iron sulfate product must then be oxidized to the iron oxide by the later addition of oxygen as follows:

4 Fe so; F8203 4H2SO The acidic reducing agent can be added as a gas or as an aqueous solution. However, sulfur dioxide, is not sufficiently soluble in water to provide an economical reaction without the further addition of gas during the reaction.

The rate of reaction for S0 is sufficiently great that the amount of ore reacted per unit time is dependent substantially upon the rate at which the reducing agent is fed to the ore. Thus, if available, substantially pure reducing gas (e.g., S0 should be utilized, both for the vapor phase reaction and for the aqueous reaction. If

If a soluble iron salt is formed and dissolved by leach water, the soluble salt, e.g., the sulfate, can be converted to the iron oxide and precipitated-from the solution by bubbling oxygen into the solutionat a tempera-.

ture of at least about 30C. Preferably, a temperature of from about 30C. to about 80C. is used and optimally of from about 40 to about 80C.

The aqueous pregnant leach solution containing the dissolved soluble metal values are separated from the insoluble solids, i.e., the reacted residue or gangue, of

the ore and the iron oxide, by any conventional liquidsolid separation procedure, e.. filtering, decanting,

only dilute gas is available: stack gases or by-products from another process, gas containing any proportion of SO can be used. Furthermore, highly dilute stack gases can be concentrated, if desired before contacting the nodules. 1

Oxygen-containing gas,- usually air, is admixed together with the reducing agent. At least sufficient oxygen to react with the metal values and reducing gas to form the desired soluble salts should be provided to avoid wasting the relatively more costly reducing agent gas. Preferably, the oxygen is present in excess so as to form a net oxidizing atmosphere in order to avoid the formation of soluble iron sulfate when water is present. Preferably, the exit gas from the reactor is substantially free of S0 v Although the reaction between the ore and the reducing agent in an aqueous medium proceeds at substantially any concentration of the 50 m the aqueous solution, it is preferred not to use solutions containing less than about'l percent by weight of thereducing agent. Most preferably, a concentration of at least about lOpercent by weight of the-reducing agent is used. Optimally a saturated 'solution, wherein additional SO is continously bubbled through the water when is contact with the ore, is used.

It is preferred that the ore be comminuted and when reacting in an aquedous medium the ore is preferably mixed with the water to form a slurry or suspension into which the acidic reducing agent and oxygen are passed.

The nodule vore is preferably comminuted, as by grinding, crushing or pulverizing, into small particles so as to increase the surface area for reaction. Preferably, the ore is comminuted to a particle. size of not greater than about 10 mesh on the US. seive scale and most preferably in. the range of from' about to about 100 mesh.

thickening-or any other procedure for separating liquids from solids. This leaching and solid-liquid separationcan be carried out batch-wise or continously but preferably by continuous countercurrent flow.

In the preferred procedure, steps 1, 2 and 3 occur substantially simultaneously, The ore is contacted with an aqueous. solution of, e.g., S0 in the presence of excess oxygen and the soluble metal salts formed are immediately leached into the solution which is separated from the remaining insoluble material, which includes iron oxide. in this preferred procedure, the ore is comminuted and contacted with the aqueous solution in conventional leaching apparatus. lit is important to separate the iron value from the other metals early in the process. Dissolved iron in the solution tends to inter- 100 g/l. The concentrations of the other metals in the leach solution are proportional to their concentration in the nodule-ore relative to manganese. Generally, the manganese salt has the limiting solubilityso that substantially all of the remaining valuable metals can be leached out with the manganese. This especially true with regard tonickel, cobalt and'copper.

Preferablymeutral water is not used as a leach liquid. The leach liquid is maintained acidic, having a pH of not greater than about 4 and preferably not greater than about 3. The optimum maximum pH of the leach liquid is about 2. A lower pH tneds to substantially increase the proportion of copper salt which tends dissolved 'At higher pH, the copper salts tend to hydrolize, forming an insoluble precipitate.

It is desirable to insurethat no unreacted acidic reducing agent, e.g., S0 remains in the pregnant leach solution. When the reaction is carried out in an aqueous medium, the resultant pregnant solution can be heated to evolve the S0 from the solution. Generally. a temperature of from about 60 to about is sufficient. Bubbling sparge gas substantially inert to the present system, such as nitrogen, carbon dioxide, air or any of the noble gases, throughthe solution aids in the removal of the reducing agent. The S0 is preferably recovered and recycled for further use in thereduction step of the process.

Preferably the leach liquid is maintained at substanleach solution, when sulfates'are soluble metal salts in order to separate them from insoluble'gangue and iron oxides, following the vapor-phase reduction reaction, or to the liquid used as the aqueous reaction medium. The pregnant leach solution contains the dissolved metal values.

Because of the rather complex mixture of materials which are obtained from such ocean floor nodules,

. many of the standard hydrometallurgical methods for separating out metal values are not directly applicable because of the presence of various interfering ions;

' Preferably, the following procedures can be utilized for separating out at least the pure cobalt, copper and nickel values from the pregnant leach solution.

For separating each of the copper, cobalt. and nickel values from the leach solution a liquid extraction procedure is most preferred.

The liquid-liquid extraction procedure requires the use of an extracting medium which is readily separable from water, which is selective for extracting one or more of the metalvalues from the aqueous leach solu tion and from which the metal value can be readily stripped.

The extracting medium should be immiscible with water to improve the economic efficiency of the process. lfthe extracting medium were not immiscible with water, a substantial loss of the extracting reagent'would occur during each extraction, by virtue ofat'least a par- The 8-hydroxyquinoline compounds, which are especially useful for the separation of the metal values in accordance with the present process, can generally be defined by the following formula:

wherein each of'the R groups can be hydrogen or a hy-- drocarbyl group or inertly-substituted hydrocarbon groups, such as alkenyl, alkyl, alkynyl, cycloalkyl, cycloalkenyl, aryl or combinations thereof, such as alkaryl, aralkyl, aral'kenyl. alkyI-cycloalkyl, etc.

At least one of the R Groups, however, must be a hy drocarbon group. Any inert substituent can be present as longas it does not adversely affect the solubility of the substituted 8-hydroxyquinolines in organic solvents nor adversely affect the solubility in the organic solvent of the metal chelate formed therefrom.

The resulting metal chelate must remain soluble at least to the extent of approximately 2 percent by weight in the organic solvent.

The preferred position ofthe hydrocarbyl substituent of the 8-hydroxyquinoline nuclear structure is such as to preferentially complex with the desired metal ion in the aqueous solution. The sum of the carbon atoms in the R groups must be at least about 8 and can be high as 24 or more. The preferred R groups are alkylbenzyl groups 'or beta-alkenyl groups containing from 12 to 18 carbon atoms, preferably attached at the R R or Rposition. The optimum position for substitution is at the Rposition to obtain the highest degree of effi ciency. For a more complete description of these hydrocarbyl-substituted 8-hydroxyquinolines, see Republic of South Africa specification No.69/4397 to Budde Jr. et al, assigned to AshlandOil, Inc.

Representative compound-s useful for ion exchange and within the scope ofthe above general formula I are: 7-octyl-benzyl-8-hydroxyquinoline, 7-dodecyl-benzyl- 8-hydroxyquinoline, 7-nonylbenzyl-8- hydroxyquinoline, 7-ditertiarybutyl-benzyl-8- hydroxyquinoline, 7-hexadecenyl-8-h'ydroxyquinoline, 7-dibenzyl-8-hydrozyquinoline, 7- dimethyldicyclopentadienyl-8-hydroxyquinoline, 7- phenyl-dodecenyl-8-hydroxyquinoline, and. the like where one or more of the hydrolcarbyl groups R are attached to ring carbon atoms in the 2nd, 3rd, 4th, 5th and 6th positions. Mixtures of these 8- hydroxyquinoline derivatives can be used if'desired.

The second preferred type of metal extractants' are the alphahydroxy oximes, which are disclosed inter alia in US. Pats. Nos. 3,224,873; 3,276,863 and 3,479,378. These materials have the general formula:

Oll N011 R c c R wherein the R, R and R groups can be any of a a of organic, hydrocarbon radicals such as aliphatic and alkyl aryl radicals. R can also be hydrogen. Preferably Rand R are unsaturated hydrocarbon or branched and R groups include in addition to hydrogen, the mono-and polyunsaturated groups such as heptenylf,

octenyl, decenyl, octadecenyl, octadecynyl, and 2- ethyl-octadecenyl.

Alkyl groups include 2-ethylhexyl, 2,3-diethylheptyl,

2-butyldecyl, 2-butylhexadecyl, 2,4-ethylbutyldodecyl,

4-butylcyclohexyl, and the like. Examples of the preferred alpha-hydroxy oximes vinclude .l9-. 7 hydroxyhexatriaconta-9,27-dien-l'8-oxime; 5,10.-

diethyl-8-hydroxytetradecan-7-oxime;

hydroxydodecane-6-oxime.

The liquid ion exchange agents, which are used for the extraction of copper, cobalt and nickel values are generally chelates and thus remove only the metal values from the solution, |eaving behind the anions.

Theabove hydroxyquinolines and oximes are compounds generally known to industry and commercially available. Any other compounds useful as selective extractants for the metal values in the aqueous systems obtained from the reduction of ocean floor nodules' 5,8-diethyl-7- ores can also be used in the process of this invention. The extracting agent can be a liquid which is itself water-immiscible but generally can be dissolved in a solvent which is substantially immiscible with water. The oximes and hydroxyquinolines are at least partially insoluble with water. it has been found to be preferable to use them in solution in a water-immiscible solvent to form a water-immiscible extraction medium to prevent loss of the extraction agent in the aqueous raffinate.

It has been found when utilizing common commercially available water-immiscible solvents that solutions containing from about 2 to about 50 percent and preferably from about 5 to about 30 percent by wt. of the extracting agent is economically useful as being sufficiently active to remove the desired metal values selec tively from the aqueous solution and being sufficiently dilute in the extracting agent so that substantially no extracting agent is leached out and lost in the aqueous raftinate. If it is desired, however, more concentrated solutions can be utilized. Mixtures of extracting agents can be-used as long as they are not jointly reactive and do not interfere with the process of this invention.

Useful solvents include generally any inert hydrocarbonswhich are solvents for the extracting agent, per se, and for the metal chelate, or, extracting agent-metal complex, and which do not react-with any of the other materials present, under the conditions of the extraction process..Generally, liquid aliphatic, cycloaliphatic, aromatic, cycloaliphatic-aromatic, aliphatic-aromatic orchlorinated such hydrocarbons are preferably utilized as the solvent-diluent for the extracting agent. Op-

.timally, the diluent-solvent has a specific gravity in the 10 is utilized and include, preferably, aliphatic alcohols containing from about 8 to about 16 carbon atoms such as n-octyl alcohol, n-decyl alcohol, n-dodecyl alcohol, n-tetradecyl alcohol, n-hexadecyl alcohol, isooctyl alcohol, 2-ethylhexyl alcohol, cyclohexanol and mixtures of these and other alcohols. Decanol is a preferred 'material.

Generally no more than the necessary amount of the phase modifier, e. g., alcohol, which is necessary to inhibit the formation of the emulsionor prevent entrainment, should be used. Usually no more than about 25 percent by volume of the phase modifier isnecessary. Preferably, from about 2 to about 10 percent by volume is satisfactory and not more than about 5 percent is most preferred. The-phase modifier can be completely eliminated if desired, and, therefore, is optional in the present procedure.

The present invention does not comprise solely the selection of the extracting medium. It is preferred that the extracting medium be a liquid. because liquidliquid extraction ofa normally solid material from solution is a relatively simple and common procedure.

However, other extraction procedures can be followed and other types of extractants used.

When utilizing liquid-liquid extraction from an aque' ous solution of mixed metal halides, a wide range of liquid can be used as a solvent-diluent that meets the following criteria:

1. A solvent for the extracting agent; 2. A solvent for-the extracting agent-metal complex,

or chelate, 3. immiscible with water; and 4. Readily separable from water. Examples of suitable solvents include benzene, toluene, xylene, aliphatic and aromatic petroleum fractions such as naphtha and derivatives thereof and mixtures of the foregoing. lnaddition to the aliphatic, aromatic, cycloaliphat'ic-aromatic, aliphatic-aromatic hydr0carbons and cycloaliphatic hydrocarbons, chlorinated such hydrocarbon liquids can also be usefully utilized.-

Light fuel oil, high flash point kerosene and other petroleum hydrocarbons, such as hexane-heptane mixtures'are preferred. Generally the aliphatic materials In addition to the solvent and the extracting agent,

there can preferably also be present in the liquid extracting medium a phase modifier which prevents formation of an emulsion with, or entrainment of, the organic phase in the aqueous phase. This is accom plished, it is believed, by altering the surface tension and related physical properties ofthe organic-aqueous mixture during extraction. These phase modifiers are generally most useful when an aliphatic solvent-diluent aqueous phase-to-aqueous-immiscible'phase volume ratios can be utilized in the present invention. Generally, using a 20 percent by wt; solution of the extracting agent, aqueous-to-aqueous immiscible phase volume, ratios of from about 10:1 to about 1:10 are desirable. The useful range of volume ratios differ proportionately for other concentrations of the extracting agent.

The above two types of extraction agents are especially preferred for the separation of the metal values found'in the leach liquidobtained from ocean floor nodules because it has been discovered, as an aspect of this invention, that a single one of these reagents can be utilized for the selective removal of all ofthe important metal values from the leach liquid. Thus, by utilizing either an a-hydroxy oxime or an 8- hydroxyquinoline, a single extracting medium can be utilized for removing, in seriatim, all of the desired metal values. It is unnecessary to utilize a multiple extractant system when utilizing these materials, but is merely necessary to vary the pH of the leach solution following each successive extraction.

Beginning withan aqueous, leach solution containing dissolved copper salt, cobalt salt, nickel salt and manganese salt, as the primary solutes, plus a variety of other metal salts in monor concentrations, the extrac' tion of the individual metals can preferably be carried out by the following general procedure with liquid ion exchange agents; I

'l. adjust the pH of the pregnant leach solution to a desirable pH, 2. mix'the pregnant leach solution with I an immiscible organic liquid containing an extractant pH ofthe raffinate as necessary. mix the raffinate with an immiscible organic liquid containing an extractant specific to another metal at the pH of the aqueous phase.fGenerally, nickel can be extracted using for example, an a-hydroxyoxime or 8-hydroxyquinoline at a pH of about 3 to about 6 and preferably about 3 to about 3.5 and cobalt can be extracted using these agents at a pH of from about 3.5 to about 7-, preferably to about 6, optimally from about 3.5 to about and the most economical results at'from about 3.5 to about 4.5. At too high a pH, the manganese, nickel and cobalt tend to precipitate and this is preferably avoided. F'urther, increasing pH too much is expensive, in using up basic reagents. Nickel and cobalt can be extracted together.

. The ratio of cobalt and nickel removed from the leach solution by the extractant is determined by the pH of the leach solution and by the volume phase ratio of organic to aqueous phases, i.e., the relative proportions of nickel and cobaltextract can be the same as that which is present in the pregnant leach solution or a greater proportion of nickel or a greater proportion of cobalt can be extracted. Generally, the higher the ,the desired pH. The chelating agents act by releasing hydrogen ions when extracting metals, and thus the pH would decrease during extraction. Caustic soda solution is preferably used. The sodium ion generally does not interfere with the further processing of any metal salt. However, other useful basic materials include generally the oxides, hydroxides and carbonates of alkali:

metals and alkaline earth metals. Such compounds include potassium hydroxide, lithium hydroxide, lithium carbonate and ammonium hydroxide and carbonate. Manganese hydroxide and manganese carbonate are especially useful as they do not .introduce any additionalmetal value. Buffering agents can also be added; however, this can add an undesirable impurity to the leach liquid.

Each extraction step can be carried out with one or more extraction stages until the desired amount of metal is extracted.

4. The metal-containing organic extractant phases can be stripped of the metal values by contacting with an aqueous stripping liquid; generally an acidic 'solution is used. Generally, following stripping the extracting solution can be recycled to the process.

Copper can be readily stripped by an aqueous min eral acid. The amountof hydrogen ion provided by the stripping liquid must be at least slightly in excess (preferally at least about 5 percent in excess) ofthe stoichioacidic aqueous solution, such as the mineral acids or the stronger organic acids, such as chloracetic acid, in a concentration of less than about 6N, preferably from about 0.01N to about 3N acid and most preferably from about 0.1N to about LON. Cobalt can then be stripped from the chelate'using a strong mineral acid aqueous solution in a concentration of at least 6N-hydrogen ion and 6N chloride ion. Strong hydrochloric acid, containing at least about percent by weight HCl is preferred.

Although the strong acid-chloride solution of cobalt can be directly used for the further reduction to cobalt metal, as in an aqueous electrolysis cell, it is preferred to extract the cobalt and then strip again to permit recycling and further use of the relatively expensive, strong, 6N acid-chloride solution. This can be done by contacting the cobalt solution with a tri-alky'l amine, or

lines and oximes.

The tri-alkyl amine solution forms a complex with the cobalt halide and can then be readily separated from the strong acid solution. The cobalt halide can be stripped from the extractant by a weakly acidic aqueous solution, i.e., a pH of not greater than about 3, which can then be used, for example, as an aqueous electrolyte for refining to the elemental metal by cathodic electroplating.

The aqueous raffinate leach solution remaining after the cobaltand nickel are removed contains substantially all of the manganese value which was leached from thenodule plus minor amountsof the salts of other metals. The raffinate can be utilized per se to ob- .tain relatively impure manganese, the degree of impuritics being ,very slight. However, ifa high quality manganese is needed, it is advisable to separate the manga' nese from the other metals. This can be done in various ways: cementation, passing the solution through-a bed of manganese metal particles, which results in the removal ofthe more noble metals by substitution therefore by manganese, or precipitation, as by sulfide precipitation of the other metals present. The remaining manganese salt in solution can then be utilized for the preparation of manganese metal by any conventional means. The presence of alkali or alkaline earth metals results in no interference at this point.

The solutions ofthe individual metal salts can then be treated in a conventional manner to reduce them to the elemental metals, e.g., by cathodic electroplating techniques. For example, manganese sulfate can be reduced to manganese in an aqueous electrolytic cell.

Copper, nickel and cobalt salts can be reduced to the respective metals from aqueous solutions in electrolytic cells.

The electrolytic procedures include the conventional methods for electrolytically reducing the salts to the elemental metals and the exact procedure forms no part of this invention. However, preferably, aqueous elec trolysis procedures are followed wherein the electrolysis solution can be utilized in stripping the metal value from the liquid ion exchange medium and thenc'an be reused directly, with or without preliminary treatment,

in the electrolysis, so as to continuously replenish the supply of electrolyte salt.

It should be noted that under this procedure the electrolyte salt, which is obtained from the liquid ion exchange medium, need not be the original salt, e.g., sulfate produced in the reaction.

sulfate salts, when the metal values are stripped from the liquid ion exchange medium the salt formed de pends upon the acid which is used for the stripping.

For a more complete explanation and description of various electrolysis, or cathodic electroplating, refining procedures, see, Graham Electroplating and Engineering Handbook (1971), for example.

Referring to the drawings accompanying this application: FIG. I is a schematic flow diagram of a procedure wherein sulfur dioxide is reacted with crushednodules in an aqueous medium.

FIG. 2 is a portion ofa procedure wherein SO vapor Alternatively, all of the nickel and cobalt can be removed in a single unit by maintaining the pH of the aqueous phase constant during this extraction such that the ratio of nickel-to-cobalt which is extracted is substantially that in the pregnant leach solution. This can be predetermined and the pH of the aqueous phase maintained to correspond to this proportion by continously adding basic material during the extraction. Generally, the higher the pH the greater the proportion of cobalt which is extracted relative to the nickel. and vice versa.

' The organic extract, which contains cobalt and nickel, is then stripped first of its nickel content using the aqueous solution from a nickel electrolysis cell. To

- this solution is added sufficient make-up sulfuric acid to increase hydrogen ion concentration to a degree suf-, ficient to at least stoichiometrically replace the nickel from the extract; generally from about 2N to about extract; N hydrogen ion concentration'is preferred. This is sufficient tostrip out nickel without removing cobalt. The aqueous phase containing nickel is then fed to the nickel electrolytic cell.

leach tank where they are slurried with water while 50-; I

and excess air are bubbled up through the water.

The liquid slurry is next passed to a filter toseparate the solid residue, comprising the ore gangue CaSO, and iron oxide, from the aqueous solution comprising the manganese, cobalt, nickel, copper and other metal values dissolved as the sulfate salts. The sulfate solution is then passed to a liquid ion exchangesystem to separate out the individual metal values.

The leach/solution filtrate is extracted with a liquid ion exchange agent specific to copper at the pH of the filtrate, approximately 2.0.- The liquid ion exchange agent,.e.g., an oxime or an 8-hydroxyquinoline' is dis solved in organic solvent medium which is immiscible with the aqueous leach liquid. The extractant solution and leach solution are contacted in any conventional liquid-liquid extraction equipment. Preferably a multistage counter-current flow extraction is carried out, either multiple mixer-settler stages or in an extraction column. The aqueous raffinate from the final stage is substantially depleted of copper.

The organic extract phase is stripped of its copper by contact with a sulfuric acid solution having a. hydrogen ion concentration of about 2N to about 6N, in this case recycled from the copper electrolytic cell. The copper is stripped out as copper sulfate, which can be directly 7 fed to the electrolytic cell. The organic extracting solu' tained at the necessary pH (3-3.5 for oximes or hy-' droxyquinolines) until most of the nickel is extracted. and the pH is then increased to/and maintained within the range of 3.5 to 4.5 untilthe remaining cobalt is extracted. The organic extract phase from the extraction system contains the cobalt and nickel, and the final raf- The remaining'organiephase layer is' then further treated with very strong aqueous solution of'HCl con- 1 taining at least 6N hydrogen ion concentration and 6N chloride ion concentration. It is necessary that there be a sufficiently high chloride ion concentration to form the tetrachlorocobalt complex, which it is believed is needed'in order to strip out cobalt. Although hydrochloric acid is preferred, as this provides both the nec 'essary hydrogen concentration and chloride concentra tion, other strong mineral acids can be utilized in combination with soluble halide salts. The strongly acidic aqueous solution'containing cobalt as the only metal can then be contacted with a 5 -30 percent solution of an organic tertiary amine, e.g., tr:i-2-ethylhexyl amine, to extract cobalt. The cobalt can be readily stripped from the amine solution using the electrolyte solution from a cobalt cell, and the aqueous stripping phase fed directly to the. electrolysis cell. The 6N HCl solution can then be recycled.

' feed for the cells.

The manganese sulfate nickel sulfate and cobalt chloride solutions are electrolyzed in aqueous electroplating cells of conventional type. The electrolysis solutionsfrom the nickel and cobalt cells are con tinously recycled as stripping liquids to pick up fresh metal salt Referring to FIG. 2 the crushed nodule ore is passed into a moving bed reactor and countercurrently contacted with S0 and air. The reacted nodules are than passed through a series of mixer-settler tanks countercurrently to water, preferably with additional air bubbled through the water. The liquid from the final settler finate aqueous phase is substantially depleted of these small quantities of salts of other metals.

tank is passed to a filter to insure the removal of all solid material. The liquid'filtrate containing the manganese, nickel, cobalt and copper values from the ore can then be passed to a liquid ion exchange separation system as in FIG. 1. y

The water which is utilized in the: leach system is originally preferably at a pH of not greater thanabout 2.

The following examples set forth preferred embodiments of the present invention, but are exemplary and not exclusive of the full range of this invention.

EXAMPLE 1 Ocean floor nodule ore was obtained having the following composition:

The nodule ore was ground to an average particle size of less than 100 mesh and 100 gram samples of the nodules were slurried in 500 grams water. SO was bubbled through the aqueous slurry at a rate of approximately 0.1 liter/min.STP, and air. at a rate of 0.5 liter/- min. STP, for about 10 minutes. The flow of S and air was discontinued. The solids are then separated from the liquid by passing the slurry through a filter.

A second sample was treated identically except that the air flow was omitted. The aqueous leach solution filtrate from each sample was analyzed and the following percentages of the original metal values present in the nodule were found to have been dissolved in the leach solution as shown in Table I.

As shown 'by the above table the addition of excess air served to substantially eleminate the iron which was carried over into the solution and increased the proportions of the other valuable metals dissolved.

EXAMPLE 2 A bed comprising 100 gms. of the-crushed nodule ore .of Example I was maintained in a fluidized condition bypassing l liter/minute STP of a mixture of S0 and air containing percent S0 and 5 percentO through a fluidized bed reactor. After 3 minutes, the ore particles were removed and passed through a two stage mixsoluble salts of divalent manganese, copper, nickel and cobalt;

(4) separating the solution from any insoluble residue of the ore;

(5) separating out an individual metal value by treat ing the aqueous solution in a liquid ion exchange process to form a solution of the individual metal in the form of a water-soluble salt;

(6) reducing the metal value to the elemental metal by cathodically electroplating from the solution of the water-soluble salt.

2. The process of claim 1 wherein the liquid ion exchange process comprises contacting the aqueous pregnant leach solution with a liquid ion exchange medium selective for the metal, separating the medium from the aqueous solution and stripping the metal value from the medium with an aqueous stripping solution.

3. The process of'claim 2 wherein the medium comprises a metal extractant selected from the group con-" reacted with the sulfur dioxide and in excess of oxygen -in an aqueous mediumto-form directly an aqueous pregnant leach solution of thewater-soluble salts of dier-settler leaching system countercurrently to'water having an initial pH of 2. The final liquid was filtered to remove solids and'the liquid leach solution was analyzed. Substantially the same results were obtained as in Example 1; the amount of dissolved iron was reduced to substantially zero, i.e., it was not detectable.

The patentable embodiments of this'invention which are claimed are as follows:

1. A process for separating metal values'from ocean floor-nodule ores, the ore comprising as primary components the oxides of manganese and iron and as secondary components compounds ofcopper, cobalt and nickel, the process comprising the steps of:

l. reacting the nodule ore, in the presence of oxygen, with a sulfur dioxide acidic reducing agent to form as reaction products the water-soluble sulfates of divalent. manganese, nickel, cobalt and copper (2) contacting the metal values with sufficient oxygen to convert substantially all of the iron present to insoluble iron oxide. (3) leaching the reacted ore with an aqueous leach liquid to form an aqueous pregnant leach solution comprising the watervalent manganese, copper, nickel and cobalt.

6. The process of claim 5 wherein the nodule ore is comminuted and the ore particles are slurried in an aqueous medium prior to reaction with the sulfur dioxide in the presence of oxygen.

7. The process of claim 1 wherein-oxygen is present in excess when theme is reacted with sulfur dioxide.

8. The process of claim 1 wherein the nodule ore is reacted with sulfur dioxide in an anhydrous environment.

9. The process of claim 1 wherein the ore and the sulfur dioxide are both at substantially ambient temperatures when they are reacted. '10. The process of claim 1 wherein the aqueous leach liquid is at substantially ambienttemperature when it contacts the reacted ore.

I ondary components compounds of copper, cobalt and nickel, the process comprising the steps of: (l) commi-.

therefrom to form separate aqueous solutions of soluble copper salt,'nickel salt. cobalt salt. and manganese salt; (6) reducing the copper to copper metal by cathodically electroplating the aqueous solution of copper (7) reducing the nickel salt and cobalt salt to elemental cobalt and nickelby cathodically electroplating respectively, and (8) reducing the manganese sulfate to 17' 18 manganese metal by cathodically electroplating the 2. Contacting the product with sufficient oxygen to aqueous solution of manganese sulfate. r convert all of the iron compounds to insoluble iron 13. The process of claim 12 wherein the liquid ion exoxide; v change agent is selected from the group consisting of 3. leaching the reacted ore with water to form an 8,-hydroxyquinolines and alphahydroxyoximes. aqueous leach solution comprising the water- 14. A process for separating metal values from ocean soluble salts of divalent mangan ese, copper, nickel floor nodule ores, the ore comprising as primary comand cobalt; a ponents the oxides of manganese and iron and as sec- 4. separating the solution from any insoluble residue ondary components compounds of copper, cobalt and of the ore; r nickel, the process comprising the steps of: 5. Separating out an individual metal value by treat- I. reacting the nodule ore, in the presence of oxygen ing the aqueous solution in a liquid ionexchange and water with an acidic reducing agent capable of process to form a solution of the individual metal reducing the tetravalent manganese and trivalent in the form of a water-soluble salt; iron present in the ores and to form a product com- 6. reducing the metal value to the elemental metal by prising the water-soluble salts of divalent mangacathodically electroplating from the solution of the nese, divalent iron, divalent nickel, divalent copper water-soluble salt. and divalent cobalt and insoluble residue; F

UNITED STATES PATENT ()FFICE CERTIFICATE OF CURRECTIQN PATENT NO. 1 3,869,360

DATED March 1975 |NVENTOR(S) i William S. Kane, et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Add at the end of (63) the following:

-a continuation-in-part of Ser. No. 309,714, November 27, 1972 and Ser. No. 309,713, November 27, 1972 now U. S. Patent numbers 3,809,624 and 3,810,827, respectively.

Column 1, line 6, after "abandoned. add the following:

-This application is further a continuation-in-part of co-pending U. S. Application Serial No. 309,714 filed on November 27, 1972 and U. 5. Application Serial No. 309,713 filed on November 27, 1972, now U. S. Patent Nos. 3,809,624 and 3,810,827 respectively.-

Column 16, line 26 (Claim 5 line 2) change "in" to an (see application Claim 2, line 2) Column 17, line 5 (Claim 13 line 3) correct "alphahydroxyoximes" to -alphahydroxyoximes- (application Claim 13, lines 2 and 3) Signed and Sealed this first Day of June1976 (sear) Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner nfParemx and Trademarks

Claims

1. A PROCESS FOR SEPARATING METAL VALUES FROM OCEAN FLOOR NODULE ORES, THE ORE COMPRISING AS PRIMARY COMPONENTS THE OXIDES OF MANGANESE AND IRON AND AS SECONDARY COMPONENTS COMPOUNDS OF COPPER, COBALT AND NICKEL, THE PROCESS COMPRISING THE STEPS OF:

1. REACTING THE NODULE ORE, IN THE PRESENCE OF OXYGEN, WITH A SULFUR DIOXIDE ACIDIC REDUCING AGENT TO FORM AS REACTION PRODUCTS THE WATER-SOLUBLE SULFATES OF DIVALENT MANGANESE, NICKEL, COBALT AND COPPER (2) CONTACTING THE METAL VALUES WITH SUFFICIENT OXYGEN TO CONVERT SUBSTANTIALLY ALL OF THE IRON PRESENT TO INSOLUBLE IRON OXIDE, (3) LEACHING THE REACTED ORE WITH AN AQUEOUS LEACH LIQUID TO FORM AN AQUEOUS PREGNANT LEACH SOLUTION COMPRISING THE WATERSOLUBLE SALTS OF DIVALENT MANGANESE, COPPER, NICKEL AND COBALT, (4) SEPARATING THE SOLUTION FROM ANY INSOLUBLE RESIDUE OF THE ORE,

2. Contacting the product with sufficient oxygen to convert all of the iron compounds to insoluble iron oxide;

3. The process of claim 2 wherein the medium comprises a metal extractant selected from the group consisting of alpha-hydroxyoximes and 8-hydroxyquinolines.

3. leaching the reacted ore with water to form an aqueous leach solution comprising the water-soluble salts of divalent manganese, copper, nickel and cobalt;

4. separating the solution from any insoluble residue of the ore;

4. The process of claim 3 wherein the metal extractant is dissolved in a water-immiscible organic liquid solvent.

5. The process of claim 1 wherein the nodule ore is reacted with the sulfur dioxide and in excess of oxygen in an aqueous medium to form directly an aqueous pregnant leach solution of the water-soluble salts of divalent manganese, copper, nickel and cobalt.

5. Separating out an individual metal value by treating the aqueous solution in a liquid ion exchange process to form a solution of the individual metal in the form of a water-soluble salt;

6. reducing the metal value to the elemental metal by cathodically electroplating from the solution of the water-soluble salt.

7. The process of claim 1 wherein oxygen is present in excess when the ore is reacted with sulfur dioxide.

9. The process of claim 1 wherein the ore and the sulfur dioxide are both at substantially ambient temperatures when they are reacted.

10. The process of claim 1 wherein the aqueous leach liquid is at substantially ambient temperature when it contacts the reacted ore.

11. The process of claim 1 wherein the leach liquid has a pH of not greater than about 3.

12. A process for separating metal values from ocean floor nodule ore, the ore comprising as primary components the oxides of manganese and of iron and as secondary components compounds of copper, cobalt and nickel, the process comprising the steps of: (1) comminuting the nodule ore; (2) reacting the nodule ore with sulfur dioxide in the presence of excess oxygen; (3) forming a pregnant leach solution comprising a solution in water of manganese sulfate, nickel sulfate, cobalt sulfate and copper sulfate and separating the pregnant leach solution from the insoluble solids; (4) separating individual metal values from the pregnant leach solution by subjecting said leach liquid to a liquid ion exchange medium and stripping individual metal values therefrom to form separate aqueous solutions of soluble copper salt, nickel salt, cobalt salt, and manganese salt; (6) reducing the copper to copper metal by cathodically electroplating the aqueous solution of copper (7) reducing the nickel salt and cobalt salt to elemental cobalt and nickel by cathodically electroplating respectively, and (8) reducing the manganese sulfate to manganese metal by cathodically electroplating the aqueous solution of manganese sulfate.

13. The process of claim 12 wherein the liquid ion exchange agent is selected from the group consisting of 8-hydroxyquinolines and alphahydroxyoximes.

14. A process for separating metal values from ocean floor nodule ores, the ore comprising as primary components the oxides of manganese and iron and as secondary components compounds of copper, cobalt and nickel, the process comprising the steps of: