JP2014194049A - Method of leaching copper from copper sulfide ore by using niter leaching liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To leach copper efficiently from day-old copper sulfide ore by using niter after-leaching liquid (caliche).SOLUTION: A leaching method for copper sulfide ore comprises leaching ore containing enargite and/or yellow pyrite as copper sulfide ore by using the niter after-leaching liquid and preferably comprises diluting niter after-leaching liquid(caliche) at an arbitrary ratio and leaching copper sulfide ore by using the diluted liquid with the pH adjusted to 1.2 or lower with a mineral acid. To leach more efficiently, an iron salt is added to the liquid for leaching the copper sulfide ore to an iron ion concentration of 2 g/L or higher.

Description

  The present invention relates to a method for efficiently leaching copper from a copper ore containing at least one of chalcopyrite or arsenite, which is a primary copper sulfide ore.

  Ores containing copper are generally divided into oxide ores and sulfide ores. Unlike oxide ores, it is difficult to efficiently recover copper by leaching with sulfuric acid, and the ores containing copper are generally processed by dry smelting.

  However, there is room for improvement in the dry smelting of sulfide ore. For example, in the case of copper sulfide ore containing arsenic, which is an environmentally undesirable element, such as arsenous copper ore, arsenic oxide may be generated by the dry smelting method, and this arsenic oxide should not be released to the atmosphere. Therefore, the arsenic processing cost is required, resulting in an ore with extremely low commercial value.

  Furthermore, in the dry treatment of sulfide ore, it is necessary to treat sulfur dioxide as a by-product. In the case of a mineral species having a high sulfur to copper ratio such as chalcopyrite, the load on the processing equipment increases.

  Therefore, for copper sulfide ores, wet processing methods that can efficiently recover copper without undergoing a heat treatment step such as roasting are preferred, but copper sulfide ores such as chalcopyrite and arsenite have very high leaching rates into mineral acids. Therefore, wet processing is very difficult for ores with high mineral content.

  As a wet processing method for minerals containing hardly soluble primary copper sulfide ore, a leaching method using iodine as a catalyst is known, as described in, for example, Japanese Patent Application Laid-Open No. 2010-24511 (Patent Document 1). It has been shown that this method can easily leach out insoluble chalcopyrite at room temperature.

In leaching using iodine as a catalyst, an oxidizing agent is required for the regeneration of iodide ions formed after iodine oxidizes chalcopyrite to iodine. Although various oxidants are considered to function for regeneration of iodide ions, Patent Document 1 describes Fe ³⁺ as an oxidant, and Fe ³⁺ is one of the mildest and cheapest oxidants. It is.

In leaching of copper sulfide ores, Fe ³⁺ is reduced to Fe ²⁺ when used for iodine catalyzed leaching. It is important in terms of leaching speed and cost to efficiently regenerate the Fe ²⁺ produced here to Fe ³⁺ . As methods for this, oxidation and aeration with chemical reagents, and methods using iron-oxidizing microorganisms have been proposed.

  Regarding a mixed ore of arsenite and chalcopyrite, JP 2012-52217 A (Patent Document 2) discloses a method of leaching copper using the oxidizing power of iodic acid in combination with catalytic leaching with iodine.

  However, leaching with only iodic acid is not efficient, and it is necessary to return the iodide ion produced by reduction of iodic acid to a form having a leaching promoting effect, as in the case of using iodine as a catalyst. That is, there is a need for a method of oxidizing iodide ions produced by reduction of iodic acid to at least iodine.

  On the other hand, iodine production, which is the key to promoting leaching by the above-mentioned method, has produced the majority of the world's production in Chile and Japan. In Chile, leaching and purifying nitrate (Kaliche ore) produces iodine. ing. Nitrile (carice ore), which is a raw material for iodine production in Chile, usually contains about 3 to 12 mass% sodium nitrate and iodic acid (iodine grade 0.04% mass).

  This glass stone (Kalice ore) is deposited, water is supplied from the top, and the leachate is collected from the bottom to obtain a liquid containing nitric acid and iodate or iodide ions. This liquid after leaching is called curice.

JP 2010-24511 A JP 2012-52217 A JP 2012-188725 A

  It is known that nitrate ions contained in carice have oxidizing power, and chalcopyrite is known to dissolve in aqueous nitric acid when heated under strongly acidic conditions. However, nitric acid does not contribute to the leaching of chalcopyrite in the range of pH 1.5 to 2, which is a normal leaching condition at room temperature.

  Nitric acid is known not to oxidize iodide ions to iodine at low concentrations. Therefore, although Carice contains an iodine compound as a catalyst and nitrate ion as an oxidizing agent, it is not applied to the leaching of primary copper sulfide ore.

  Carice himself has the potential as an oxidative leachate of copper sulfide ore, considering its contents, and it is beneficial for copper hydrometallurgy if it can be applied to the leaching of copper sulfide ore because it is produced in large quantities in Chile.

On the other hand, as shown in JP 2012-188725 A (Patent Document 3), in the wet treatment of sulfide minerals using iodine, the Fe ³⁺ which is an oxidant is regenerated and then Fe is separated after the separation. A method for microbial oxidation of ²⁺ by iron-oxidizing bacteria has been proposed. However, the nitrate ion contained in the carice has microbial toxicity, and it is impossible for the microorganism to stably regenerate Fe ³⁺ .

A method of providing a process for removing microbial toxic substances or a method of chemically supplying various reagents such as hydrogen peroxide continuously as an oxidizing agent for Fe ³⁺ oxidation regeneration is preferable in terms of cost. Absent.

Moreover, although the cost of iodine becomes a problem in the method disclosed in Patent Document 1, a leachate (carice) of nitrate (carice ore) abundantly present in Chile as a raw material for iodine or nitric acid is used directly in wet processing of copper sulfide ore. If it is possible, it is expected to use iodine without going through a purification step. However, since normal leaching conditions cannot efficiently oxidize iodide ions and Fe ²⁺ using nitric acid contained in carice as an oxidizing agent, carice only serves as an iodine source.

Further using Kariche as iodine source, further case of leach copper sulfide ore with the addition of Fe ^3+, As described above for the high concentration of nitrate ions contained in Kariche, not play Fe ³⁺ by using microorganisms . Although Carice is attractive for the above reasons, it has many problems to be applied to the leaching of primary copper sulfide ore and has not been put into practical use.

In other words, Carice is not suitable because it cannot regenerate Fe ³⁺ as the final electron acceptor when applied to the leaching of primary copper sulfide ore using conventional iodine as a catalyst, although it is a preferred iodine source in terms of cost. On the other hand, Carice has a large amount of nitrate ions, but at normal temperature, nitric acid does not act as an oxidizing agent for regenerating iodine from iodide ions, and there are two problems in that there is no leaching promoting effect.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have adjusted the pH of a solution after leaching calcite (carice), which is generally weakly acidic to weakly basic, to 1.2 or less when leaching the primary copper sulfide ore. Then, a method for leaching copper was found by using this as a leaching solution. The solution after leaching of the stone is sufficient if it contains at least iodate ions or iodide ions, iron salts and nitrate ions as an iodine source.

That is, this description includes the following inventions.
(1) A method of leaching copper sulfide ore in which an ore containing at least one of arsenite or chalcopyrite as copper sulfide ore is leached using a solution after leaching of nitrate.
(2) The leaching method according to (1), wherein the solution after leaching of nitrate is adjusted to a pH of 1.2 or less with mineral acid.
(3) The leaching method according to (1) or (2), wherein the solution after leaching of nitrate contains either or both iodate ions and iodide ions.
(4) The leaching method according to any one of (1) to (3), wherein the nitrate ion contained in the solution after leaching of glass stone is 10 g / L or more.
(5) Any one of (1) to (4), wherein when leaching copper sulfide ore using the solution after leaching of nitrate, leaching is performed by adding iron ions to 2 g / L or more. The leaching method described in 1.

  According to the method of the present invention, copper leaching can be efficiently and inexpensively performed by adjusting the solution after nitrite leaching to pH 1.2 or less and using it as the leaching solution for primary copper sulfide ore.

It is a diagram which shows typically reaction in this invention. It is a graph which shows a time-dependent change of a copper concentration when chalcopyrite concentrate is leached with the simulated fluorite leaching solution by various pH. It is a graph which shows the time-dependent change of Fe2 ⁺ density ^| concentration when chalcopyrite concentrate is leached with the simulated fluorite leaching liquid by various pH. It is a graph which shows a time-dependent change of a copper concentration when a chalcopyrite concentrate is leached with a nitrite leachate. It is a graph which shows a time-dependent change of a Fe2 ⁺ density ^| concentration when the chalcopyrite concentrate is leached with the nitrite leachate with the simulated fluorite leachate. It is a graph which shows a time-dependent change of copper concentration when chalcopyrite concentrate is leached with the simulated nitrite leachate of various sodium nitrate concentration. It is a graph which shows a time-dependent change of Fe2 ⁺ density ^| concentration when the chalcopyrite concentrate is leached with the simulated nitrite leaching solution of various sodium nitrate concentration.

In the present invention, when ore containing at least one of arsenite or chalcopyrite as the copper sulfide ore is acid leached, a liquid after leaching of nitrite (Kalice) is used as the leaching solution, and the pH of the cariche is adjusted to 1.2 or less Furthermore, it is characterized by leaching copper sulfide ore by containing Fe ³⁺ .

  According to the present invention, carice containing a water-soluble iodine source (iodate ion and / or iodide ion) and nitric acid that is a Lewis acid for promoting the advance of primary copper sulfide ore is diluted at an arbitrary ratio. By adding an appropriate amount of iron ions and adjusting the pH to 1.2 or less, primary copper sulfide ore can be efficiently leached.

That is, the mechanism of this reaction is as follows.
When the iodine source is iodic acid, iodic acid first oxidizes copper sulfide ore and is reduced to iodide ions. Iodide ions are oxidized to nitric acid to form elemental iodine, which oxidizes and leaches sparingly soluble primary copper sulfide ores. However, since the reaction between iodide ions and nitric acid is very slow, it is preferable to add Fe ³⁺ which is highly reactive with iodide ions.

Although Fe ³⁺ reacts with iodide ions to become Fe ²⁺ , it is oxidized again to Fe ³⁺ by nitric acid present at a high concentration in the leachate. Fe ²⁺ is more susceptible to oxidation by nitric acid than iodide ions. The iodide ions are oxidized again by the regenerated Fe ³⁺ ions, and the copper sulfide ore is oxidized by the produced iodine to leached copper.

  This reaction is schematically shown in FIG. 1, and the final electron acceptor is nitrate ion.

  At this time, if the pH of the leaching solution used is too high, the function of nitric acid as a Lewis acid is greatly reduced, which may be undesirable for the oxidation of iron ions. From such a viewpoint, the pH of the leachate is preferably, for example, 1.2 or less, and more preferably 1.0 or less. It can be inferred from (Equation 1) and (Equation 2) that the oxidizing power of nitric acid increases under acidic conditions, but it is not known that the catalytic reaction shown in FIG.

(Formula 1)
_{^{NO 3 - + 2H + + e}} ⇔ NO 2 + H 2 O E 0 = 0.81V
(Formula 2)
NO ₃ ⁻ + 4H ⁺ + 3e ＮＯ NO + 2H ₂ O E ₀ = 0.95V

  The concentration of nitrate ions in the leachate is not particularly specified, but if it is too small, the effect is difficult to appear, and it is preferably 10 g / L or more, and more preferably in the range of 10 g / L to 35 g / L. This concentration range can be easily set by appropriately diluting the curice.

  According to the present invention, the leaching of copper sulfide ore can be used directly without refining the curice obtained by leaching the nitrate. Moreover, in this leaching method, copper can be recovered at low cost without using the microbial reaction known in Patent Document 3.

Regarding the iron to be added, it is possible to use a solution containing Fe ³⁺ such as a reagent containing Fe ³⁺ such as ferric sulfate or ferric chloride, or an acidic leachate of iron oxide. From the viewpoint that the leaching rate increases as the Fe ³⁺ concentration increases, the concentration is preferably 2 g / L or more, but the cost increases. In addition, if the concentration of Fe ³⁺ becomes too high, problems such as affecting ion selectivity during extraction may occur in the solvent extraction step following the leaching step. Therefore, the Fe ³⁺ concentration in the leachate is preferably in the range of 2 to 15 g / L.

Be added Fe ²⁺ rather than Fe ³⁺ if pH range of the Fe ²⁺ is oxidized, but the same effect because the Fe ³⁺ is obtained, from the initial state Fe ²⁺ Fe ^Since the oxidation reaction to ³⁺ is required, especially the initial leaching rate is somewhat reduced.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

Example 1
Chilean copper concentrate was used as the copper sulfide ore to be leached. The grade of this concentrate was 28% Cu, 28% Fe, and 32% S by weight, and 90 mass% of the minerals contained was chalcopyrite. The reagent used was a special grade reagent manufactured by Wako Pure Chemical Industries. A 500 ml Sakaguchi flask contains 3 g of this copper concentrate and 4.5 g of Fe ³⁺ as ferric sulfate and is adjusted to the specified pH (1.0, 1.2, 1.3, 1.4). 300 mL of sulfuric acid leachate (added to this volume of sulfuric acid solution equivalent to 30 g / L sodium nitrate and 170 mg potassium iodate (KIO ₃ )) was shaken at 30 ° C. and 120 rpm, and the sulfuric acid solution was appropriately collected. After filtration, the concentrations of dissolved Cu and total Fe were measured by ICP-AES. Further, the Fe ²⁺ concentration was measured by a dichromate titration method. The results are shown in FIGS.

(Comparative Example 1)
The pH was adjusted to 1.0 without adding Fe ³⁺ , and the concentrate was leached under the same conditions as in Example 1. The Cu, total Fe, and Fe ²⁺ concentrations were measured as appropriate. The results are shown in FIGS.

From the results of Example 1 and Comparative Example 1, it can be seen that copper leaching is promoted only under the condition of adding Fe ³⁺ . Further, only when the pH was 1.2 or less, significant oxidation of Fe ²⁺ to Fe ³⁺ was observed after 7 days of leaching. From this result, it was confirmed that Fe ³⁺ regeneration was possible using nitric acid as an oxidizing agent.

(Example 2)
2 L of water was added to 1 kg of Chilean nitrate and left for 2 weeks to dissolve the water-soluble components in the nitrate. The nitrate ion concentration in the aqueous solution was 31 g / L, and the iodine concentration was 270 mg / L.
Add 500g of Chilean copper concentrate (mainly chalcopyrite, copper grade 30% mass) to a 500ml Sakaguchi flask, add sulfuric acid to adjust the pH to 1.0 and add 300g of calice leachate and 10g as Fe ³⁺ / L ferric sulfate is added, shaken at 30 ° C. and 120 rpm, a sulfuric acid solution is collected at regular intervals, and after filtration, the concentrations of dissolved Cu and total Fe are measured by ICP-AES did. Further, the Fe ²⁺ concentration was measured by a dichromate titration method. The results are shown in FIGS.

(Comparative Example 2)
The concentrate was leached using the same leachate as in Example 2 without adding ferric sulfate to pH 1.4.

From the results of Example 2 and Comparative Example 2, the same effects as in Example 1 were confirmed when using the leaching solution of nitrate adjusted to pH 1.0 and pH 1.4, respectively. However, from the viewpoint of oxidation from Fe ²⁺ to Fe ³⁺ , the sustainability was confirmed when the pH was adjusted to 1.0 compared with the case where the nitrate leaching solution was adjusted to pH 1.4. It was confirmed that the pH of the solution affects the efficiency of copper leaching.

(Example 3)
In Example 1, the concentrate was leached under the same conditions as in Example 1 except that the amount of Fe ³⁺ to be added was 0.6 g using a nitrate leaching solution (300 mL) containing 15 g / L of sodium nitrate. The Cu, total Fe, and Fe ²⁺ concentrations were measured as appropriate. The results are shown in FIGS.

Example 4
In Example 1, the concentrate was leached under the same conditions as in Example 1 except that 3 g of Fe ³⁺ to be added was used using a nitrite leaching solution (300 mL) containing 45 g / L of sodium nitrate. The Cu, total Fe, and Fe ²⁺ concentrations were measured as appropriate. The results are shown in FIGS.

(Comparative Example 3)
In Example 3, the concentrate was leached under the same conditions as in Example 3 except that 300 mL of a sulfuric acid solution not containing sodium nitrate and containing 10 g / L of Fe ³⁺ was used instead of the nitrate leaching solution. The Cu, total Fe, and Fe ²⁺ concentrations were measured as appropriate. The results are shown in FIGS.

From the results of Example 3, Example 4, and Comparative Example 3, it can be seen that the Fe ²⁺ ions disappeared and were oxidized only when the leaching solution used for copper leaching contained nitric acid (sodium nitrate). Moreover, it has confirmed that there was a copper leaching promotion effect with nitrate ion 10g / L-35g / L.

Claims (5)

  A method of leaching copper sulfide ore comprising leaching after ore leaching with respect to ore containing at least one of arsenite or chalcopyrite as copper sulfide ore.   The method according to claim 1, wherein the solution after leaching of nitrate is adjusted to a pH of 1.2 or less with a mineral acid.   The method according to claim 1 or 2, wherein the solution after leaching of nitrate contains either or both of iodate ions and iodide ions.   The method according to any one of claims 1 to 3, wherein the nitrate ion contained in the solution after leaching of nitrate is 10 g / L or more.   The leaching is performed by adding iron ions so as to be 2 g / L or more when leaching copper sulfide ore using the solution after leaching of nitrate. Method.

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