WO2013021438A1 - Method for leaching out copper - Google Patents

Abstract

Provided is a method for leaching out copper from a copper sulfide ore using a sulfuric acid solution containing an iron-oxidizing bacterium and silver without decreasing the growth of the iron-oxidizing bacterium and without deteriorating the iron-oxidizing ability of the iron-oxidizing bacterium. A method for leaching out copper from a copper sulfide ore using a sulfuric acid solution containing an iron-oxidizing bacterium, a phenolic compound and silver as a leaching solution.

Description

Copper leaching method

The present invention relates to a method for efficiently leaching copper from copper sulfide ore, particularly copper sulfide ore or concentrate containing chalcopyrite.

In general, the leaching form of copper sulfide ore by hydrometallurgy is a leaching form (tank leaching) by batch stirring reaction using sulfuric acid or hydrochloric acid, and a liquid that drops by gravity by supplying sulfuric acid or hydrochloric acid from the top and forming a laminate. There are known leaching forms (heap leaching) and the like. In addition, a method (bioleaching) in which copper is efficiently exposed and recovered with the help of bacteria such as iron-oxidizing bacteria is also employed. In bioleaching, iron (II) ions in the leachate are oxidized to iron (III) ions, which are oxidizing agents, by iron-oxidizing bacteria, and copper in the ore is eluted by the iron (III) ions. In addition, sulfur contained in the ore is oxidized by sulfur-oxidizing bacteria to become sulfuric acid, and copper in the ore is also leached by this sulfuric acid.

Copper sulfide ore hydrometallurgy has been put to practical use for secondary copper sulfide ores such as chalcocite and copper indigo. However, chalcopyrite, which is present in the largest amount among copper resources, has an extremely slow copper leaching rate compared to secondary copper sulfide ore, and it is difficult to leach copper efficiently.

Therefore, various techniques have been proposed to increase the leaching rate of copper from copper sulfide ores mainly composed of chalcopyrite. For example, an example of performing exudation by adding activated carbon and iron to the leachate and maintaining the oxidation-reduction potential (Ag-AgCl electrode standard) at 350 to 450 mV (Patent Document 1), or pressurizing to above atmospheric pressure, 100 A method of leaching by heating to more than 0 ° C. has been reported (Patent Documents 2 to 4). However, although these leaching methods are effective in improving the leaching rate, there is a problem that the cost becomes high.

In addition to the technique described above, an example in which silver promotes leaching of chalcopyrite has been reported (Patent Document 5). However, it has also been reported that the iron oxidizing ability of iron-oxidizing bacteria is inhibited by silver (Non-patent Document 1), and it is difficult to combine silver leaching and bioleaching in the leaching of chalcopyrite. In order to solve this problem, a copper sulfide ore leaching process in which a leaching tank and a bacterial culture tank are separated has been devised (Non-Patent Document 2), but considering the cost and ease of operation, It is desirable to culture bacteria.
It is known that the effect of adding an organic nitrogen source during the cultivation of iron-oxidizing bacteria on the iron-oxidizing ability is up to 20% at the maximum, and there is no significant effect. (Non-Patent Document 3). On the other hand, when leaching copper using a sulfuric acid solution containing iron-oxidizing bacteria and silver added from copper sulfide ores containing chalcopyrite, the leaching rate of copper can be increased by adding an appropriate amount of natural nitrogenous organic substances such as corn steep liquor. It has been found to improve (Patent Document 6).

Japanese Patent Laid-Open No. 2005-15864 JP 2003-328050 A JP-T-2001-515145 Japanese Patent Laid-Open No. 10-317072 US Pat. No. 3,856,913 Japanese Patent Application No. 2009-248978

De, G. et al. C. , And three others, Hydrometallurgy, (Netherlands), 1996, Vol. 41, p. 211-229 F, Carranza, 2 others, Hydrometallurgy, (Netherlands), 1997, Vol. 44, p, 29-42 OLLI H. TUOVINEN. , And two others, Applied and Environmental Microbiology (APPLIED AND ENVIRONMENTAL MICROBIOLOGY), (USA), 1979, Vol. 37, p. 954-958

As mentioned above, it is known that the addition of silver is effective for efficiently leaching copper from chalcopyrite, which is mainly composed of chalcopyrite. There is a problem that the growth rate and iron oxidation rate ability of iron-oxidizing bacteria are reduced due to inhibition, and it is difficult to efficiently leach copper while taking advantage of both.
In view of the circumstances as described above, the object of the present invention is to reduce the growth of iron-oxidizing bacteria and the ability to oxidize iron during copper leaching from copper sulfide ore using a sulfuric acid solution added with iron-oxidizing bacteria and silver. The object is to provide a method for leaching copper.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have conducted leaching of copper using a sulfuric acid solution containing iron-oxidizing bacteria and silver added from copper sulfide ore, particularly copper sulfide ore containing chalcopyrite, It has been found that the leaching rate of copper is improved by adding an appropriate amount of a phenolic compound such as lignin sulfonic acid, a salt thereof, and condensed tannins. The present invention has been completed based on such findings.

That is, the present invention includes the following inventions.
(1) A method for leaching copper from copper sulfide ore using a sulfuric acid solution to which iron-oxidizing bacteria, a phenolic compound and silver are added as a leaching solution.
(2) The method according to (1), wherein sulfur-oxidizing bacteria are further added to the sulfuric acid solution.
(3) The method according to (1) or (2), wherein the copper sulfide ore is a copper sulfide ore or concentrate containing chalcopyrite.
(4) The method according to any one of (1) to (3), wherein the phenolic compound is one or more compounds selected from the group consisting of lignin sulfonic acid, salts thereof, and condensed tanenes.
(5) The method according to any one of (1) to (4), wherein the total concentration of the phenolic compound in the leachate is 1 to 100 mg / L.
(6) The method according to any one of (1) to (5), wherein the concentration of silver in the leachate is 1 to 50 mg / L.
(7) The method according to any one of (1) to (6), wherein calcium lignin sulfonate is added as a phenolic compound.
(8) The method according to any one of (1) to (7), wherein wattle tannin and / or quebracho tannin is added as a phenolic compound.

According to the method of the present invention,
(1) Copper can be efficiently leached at room temperature from copper sulfide ores containing chalcopyrite.
(2) During the leaching of copper from copper sulfide ore using an iron-oxidizing bacterium and a sulfuric acid solution to which silver is added, a phenolic compound is added to promote the growth of bacteria such as iron-oxidizing bacteria, thereby becoming an oxidizing agent. The production rate of iron (III) ions can be increased, and the leaching rate of copper can be improved by a synergistic effect with silver as a catalyst for copper sulfide ore leaching.

The effect of promoting copper leaching by calcium lignin sulfonate is shown. The copper leaching promotion effect by condensed tannin is shown. The effect of silver concentration on copper leaching is shown. It shows the effect of the presence or absence of bacteria on copper leaching.

The present invention is characterized in that a phenolic compound is added during the leaching of copper from a copper sulfide ore, particularly a copper sulfide ore containing chalcopyrite, using a sulfuric acid solution to which iron-oxidizing bacteria and silver are added. Although there is no restriction | limiting in particular as a sulfuric acid solution, Generally pH is 0.5-4, Typically, pH can be about 1.0-2.5. Further, one or more salts such as ammonium sulfate, dipotassium hydrogen phosphate, magnesium sulfate, potassium chloride, calcium nitrate, and potassium dihydrogen phosphate may be appropriately blended for the reason of assisting bacterial growth. The copper sulfide ore containing chalcopyrite which is a typical target ore of the method of the present invention may be either a copper sulfide ore mainly composed of chalcopyrite or a copper sulfide ore partially containing chalcopyrite. The total content is not particularly limited, but is preferably a copper sulfide ore concentrate containing chalcopyrite as a main component in that a copper leaching effect can be sufficiently obtained by the method of the present invention.

It is considered that the dissolution and leaching of chalcopyrite by the method of the present invention proceeds by a series of catalytic reactions with silver shown in the following (formula 1) and (formula 2).
[Chemical 1]
CuFeS ₂ + 4Ag ⁺ → Cu ²⁺ + Fe ²⁺ + 2Ag ₂ S (Formula 1)
[Chemical 2]
Ag ₂ S + 2Fe ³⁺ → 2Ag ⁺ + S + 2Fe ²⁺ (Formula 2)

In order to rapidly advance the catalytic reaction shown in (Formula 1) and (Formula 2), the silver concentration in the leachate is 1 to 200 mg / L, preferably 5 to 150 mg / L, more preferably 10 to 100 mg / L. It is desirable to add silver. When silver is added, its form can be added in the form of a salt such as silver nitrate, silver chloride or silver sulfide. Silver may be added in a solid state such as powder or granules, or may be added as a solution, but a silver nitrate solution is desirable from the viewpoint of handling.

When the sum of both sides of (Equation 1) and (Equation 2) is taken, the silver component is eliminated and (Equation 3) is obtained. At this time, as can be seen from (Equation 3), the final electron acceptor of the catalytic reaction with silver is iron (III) ion, and this iron (III) ion is iron (II) in the leachate as shown in (Equation 4). ) Produced by oxidation of ions by iron-oxidizing bacteria. That is, in the bioleaching using silver as a catalyst, the leaching rate of copper from chalcopyrite is limited by the production reaction of iron (III) ions shown in (Formula 4).
[Chemical formula 3]
CuFeS ₂ + 4Fe ³⁺ → Cu ²⁺ + 5Fe ²⁺ + 2S (Formula 3)
[Chemical formula 4]
4Fe ²⁺ + 4H ⁺ + O ₂ → 4Fe ³⁺ + 2H ₂ O (Formula 4)

In other words, in order to promote this reaction, it is important that the iron oxidation reaction by the iron-oxidizing bacteria proceeds or is promoted without inhibition. For this purpose, the presence of iron-oxidizing bacteria is essential for this reaction. In addition, as shown by Formula (3), elemental sulfur is produced by oxidation of chalcopyrite, but sulfur-oxidizing bacteria that oxidize it may exist, and leaching may be promoted by sulfur-oxidizing bacteria.

As for the iron-oxidizing bacterium, any iron-oxidizing bacterium generally existing in nature can be used as long as it has an ability to oxidize iron under sulfuric acid acidic conditions. As these iron-oxidizing bacteria, Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, Leptospirillum ferrifilum, etc. are generally known, and these bacteria can be selectively grown in a liquid containing iron ions without separating those in nature. In addition, microorganisms isolated from the natural world can be used after being artificially cultured and added with a nutrient source or the like.
The same applies to sulfur-oxidizing bacteria, and iron-oxidizing bacteria generally existing in nature can be used. The sulfur-oxidizing bacterium is not particularly limited as long as it is a bacterium that has the ability to oxidize sulfur and produce sulfuric acid in an aqueous system or soil, and, for example, Acidibiobacterium thiooxidans can be used.

In the leaching of copper sulfide ore using a sulfuric acid solution containing silver, the growth of iron-oxidizing bacteria is promoted by adding an appropriate phenolic compound, and the production of iron (III) ions by the iron-oxidizing bacteria shown in (Formula 4) The rate of reaction can be improved. As a result, rapid leaching of copper from chalcopyrite becomes possible.

The above-mentioned phenolic compounds include, but are not limited to, lignin sulfonic acid, humic acid, nitrohumic acid, gallic acid, chlorogenic acid, ethyl 3,4-dihydroxycinnamic acid, syringic acid, ferulic acid, vanillic acid, ascorbine Acid, 6,7-dihydroxy-2-naphthalenesulfonic acid, salts thereof, lignin, tannin, catechin, urushiol, hesperidin, hinokitiol, pyrocatechol, hydroquinone, t-butylhydroquinone, phenylhydroquinone, trimethylhydroquinone, pyrogallol, lauryl Gallate, octyl gallate, vanillin, o-vanillin, vanillyl alcohol, 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, anthrarobin, alizarin, quinizarin, o-aminoph Nord, and p- aminophenol. Among them, lignin sulfonic acid, its salt, and condensed tannins are preferably used. The said compound may be added independently and may be added in combination of 2 or more type.

The lignin sulfonic acid and its salt used in the present invention are compounds having a functional group such as a sulfone group, a carboxyl group, and a phenolic hydroxyl group, and may be, for example, calcium lignin sulfonate. Specifically, commercially available products such as those manufactured by Kishida Chemical Co., Ltd. and Nippon Paper Chemicals Co., Ltd. can be used. Condensed tannins can be obtained from plants such as mimosa, camellia and quebracho. Specifically, it is commercially available as a product from Fuji Chemical Industries, etc., and contains wattle tannin containing 50.0% by mass or more (UV method) of tannin and 60.0% by mass or more of tannin (UV method). Quebracho tannins can be used.

As a result of investigation, when the amount of phenolic compound added is too small, the effect of copper leaching from copper sulfide ore by silver is small. On the other hand, when phenolic compound is added excessively, the effect of silver leaching from copper sulfide ore by copper is promoted. It was also found that was canceled out. That is, the phenolic compound concentration in the leachate has an appropriate range for obtaining a high copper leaching promoting effect, preferably 1 to 100 mg / L, and more preferably 5 to 20 mg / L. When a phenolic compound is added at a concentration exceeding 100 mg / L, the copper leaching promoting effect is significantly reduced.

The temperature at the time of leaching may be 20 to 80 ° C. at which naturally-occurring iron-oxidizing bacteria can grow, but it is 20 to 40 ° C. because the economical mesophilic iron-oxidizing bacteria have high activity. Is desirable.

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

(Example 1) Copper leaching promotion effect by calcium lignin sulfonate As a target ore, a copper concentrate produced from candelaria which mainly contains chalcopyrite was used. This grade was Cu: 30 mass%, Fe: 28 mass%, and S: 32 mass%.

A leachate prepared by adjusting 3 g of the above concentrate to pH 1.8 with sulfuric acid (ammonium sulfate 3 g / L, potassium hydrogen phosphate 0.5 g / L, magnesium sulfate heptahydrate 0.5 g / L, potassium chloride 0.1 g / L) (Including) 300 mL, and poured into a 500 mL volumetric flask.
Silver nitrate, bacteria (iron-oxidizing bacteria and sulfur-oxidizing bacteria), and calcium lignin sulfonate (manufactured by Kinder Chemical) were added (or added) at the concentrations shown below to the leachate in the flask to obtain leachates A to C, Each leachate was gently shaken at 30 ° C. to leach copper from the copper concentrate. Here, as an iron-oxidizing bacterium, Acidithiobacillus ferroxldans sp. FTH6B forest (NITE BP-780), Acidiobacillus thiooxidans sp. TTH19A (NITE BP-164) strain was used and added so that the bacterial concentration was 10 ⁷ cells / mL.

(Leachate A)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: Added Calcium lignin sulfonate: No added (Leachate B)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: Added Calcium lignin sulfonate: 10 mg / L
(Leachate C)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: Added Calcium lignin sulfonate: 100 mg / L

With respect to the leachate A to C, the time course of the copper concentration in the supernatant was measured with an ICP emission spectroscopic analyzer (ICP-AES). The result of converting the copper concentration into the leaching rate is shown in FIG.

From this result, it was confirmed that the leaching of copper was promoted by adding 10 to 100 mg / L of calcium lignin sulfonate compared to the case of no addition. This is thought to be because the growth of iron-oxidizing bacteria was promoted by the addition of calcium lignin sulfonate, and the production rate of iron (III) ions as an oxidizing agent was improved. However, when comparing the results of the exudates B and C, when 100 mg / L of calcium lignin sulfonate is added, the leaching rate of copper is lower than when 10 mg / L is added. This shows that excessive addition of calcium lignin sulfonate begins to inhibit leaching promotion.

(Example 2) Copper leaching promotion effect by condensed tannic acid Silver nitrate, bacteria (iron-oxidizing bacteria and sulfur-oxidizing bacteria), condensed tannins (Watru manufactured by Fuji Chemical Industry) were added to the leaching solution in the flask described in Example 1. Tannin or quebracho tannin) is added (or not added) at the following concentrations, and silver nitrate is added (or not added) at the following concentrations to form exudates D to G. The copper was leached from the copper concentrate with gentle shaking. For iron-oxidizing bacteria and sulfur-oxidizing bacteria, the same strains as in Example 1 are used, and the addition amount is also the same as in Example 1.

(Leachate D)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: Condensed tannins with addition: No addition (leaching solution E)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: With addition Watlutannin: 10 mg / L
(Manju fluid F)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: With addition Kebrachotanene: 10mg / L
(Manju G)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: With addition Watlutannin: 100 mg / L

With respect to the leachate D to G, the change over time in the copper concentration of the supernatant was measured by ICP-AES. The result of converting the copper concentration into the leaching rate is shown in FIG.

From the results of the leaching solutions D to G, it was confirmed that the leaching of copper was promoted by adding 10-100 mg / L of wattle tannin and 10 mg / L of quebracho tannin compared to the case of no addition. This is thought to be because the growth of iron-oxidizing bacteria was promoted by the addition of condensed tannin, and the production rate of iron (III) ions as an oxidizing agent was improved.

Example 3 Effect of Silver Concentration Silver nitrate, bacteria (iron-oxidizing bacteria and sulfur-oxidizing bacteria), and calcium lignin sulfonate were added to the exudate in the flask described in Example 1 at the concentrations shown below (or not added). ) Add silver nitrate and iron (III) sulfate at the following concentrations (or no addition) to make leachate H to J, and gently leach each leachate at 30 ° C to leach copper from the copper concentrate. I let you. For iron-oxidizing bacteria and sulfur-oxidizing bacteria, the same strains as in Example 1 are used, and the addition amount is also the same as in Example 1.

(Leachate H)
Silver nitrate: 0mg / L (as silver concentration)
Bacteria: With addition iron sulfate (III): 6g / L
Calcium lignin sulfonate: 10mg / L
(Leachate I)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: With addition iron sulfate (III): 6g / L
Calcium lignin sulfonate: 10mg / L
(Leachate J)
Silver nitrate: 100mg / L (as silver concentration)
Bacteria: With addition iron sulfate (III): 6g / L
Calcium lignin sulfonate: 10mg / L

With respect to the leachate H to J, the time course of the copper concentration in the supernatant was measured by ICP-AES. The result of converting the copper concentration into the leaching rate is shown in FIG.

It was confirmed that there was no significant difference in the leaching rate of copper when the amount of silver added was 10 mg / L or more. From this fact, it is considered that when the calcium lignin sulfonate concentration is 10 mg / L, the iron oxidizing ability of the iron-oxidizing bacteria is not inhibited by silver in the range of the silver concentration up to 100 mg / L. Further, from the result of the leachate H, it was also confirmed that almost no copper was leached when silver was not contained in the leachate.

(Example 4) Effect of presence or absence of addition of bacteria Silver leachate, bacteria (iron-oxidizing bacteria and sulfur-oxidizing bacteria), and tannic acid were added to the leachate in the flask described in Example 1 at the concentrations shown below, respectively, and leachate K , L and M, and each leachate was gently shaken at 30 ° C. to leach copper from the copper concentrate. For iron-oxidizing bacteria and sulfur-oxidizing bacteria, the same strains as in Example 1 are used, and the addition amount is also the same as in Example 1.

(Leachate K)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: Iron-oxidizing bacteria and sulfur-oxidizing bacteria added Wat wurtannin: 100 mg / L
(Leachate L)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: only iron-oxidizing bacteria added Wat wurtannin: 100 mg / L
(Leachate M)
Silver nitrate: 10mg / L (as silver concentration)
Bacteria: No addition Watlutannin: 100 mg / L

With respect to the leachate K to M, the time course of the copper concentration in the supernatant was measured by ICP-AES. The result of calculating the copper concentration to the leaching rate is shown in FIG.

From the comparison of the results of the leachates K to M, it was confirmed that almost no copper was leached when no bacteria were added. This is because iron (III) ions are hardly produced when iron-oxidizing bacteria are not present in the system. In addition, comparing the results of the exudate K and the exudate L, it was confirmed that the leaching was promoted and the leaching rate was higher when the iron oxidizer and the sulfur oxidizer were mixed than the iron oxidizer alone. . In the leachate K and the leachate L to which bacteria were added, the bacteria concentration reached a maximum of 10 ⁹ Cells / mL.

Claims (8)

A method of leaching copper from copper sulfide ore using a sulfuric acid solution containing iron-oxidizing bacteria, phenolic compounds and silver as a leaching solution. The method according to claim 1, wherein sulfur-oxidizing bacteria are further added to the sulfuric acid solution. The method according to claim 1 or 2, wherein the copper sulfide ore is a copper sulfide ore or concentrate containing chalcopyrite. The method according to any one of claims 1 to 3, wherein the phenolic compound is one or more compounds selected from the group consisting of lignin sulfonic acid, salts thereof, and condensed tanenes. The method according to any one of claims 1 to 4, wherein the total concentration of the phenolic compound in the leachate is 1 to 100 mg / L. The method according to any one of claims 1 to 5, wherein the concentration of silver in the leachate is 1 to 50 mg / L. The method according to any one of claims 1 to 6, wherein calcium lignin sulfonate is added as a phenolic compound. The method according to any one of claims 1 to 7, wherein wattle tannin and / or quebracho tannin is added as a phenolic compound.

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