JP5840642B2 - Method for recovering gold from sulfide minerals - Google Patents

Description

  The present invention relates to a method for recovering gold from sulfide minerals.

  In recent years, a technique for recovering copper from sulfide ore by a wet method instead of the conventional dry method has attracted attention. The sulfide ore often contains a precious metal such as gold in a small amount, and a method for economically recovering the precious metal such as gold in addition to copper is required.

  As a technology for addressing such problems, alkali metal or alkaline earth metal chlorides and bromides and copper and iron chlorides or bromides are used, and the gold leaching process is performed on the residue after the copper leaching process. A method of carrying out is known (Japanese Patent Laid-Open No. 2009-235519). According to this method, it is said that copper and gold in copper sulfide ore can be leached and recovered at a high leaching rate only by using air without using a special oxidizing agent.

  Also, using the fact that gold leaching is performed when the copper quality in the residue after the copper leaching process becomes 7.9% or less, the copper quality in the residue after the copper leaching process is reduced to 7.9% or less. A method of performing the gold leaching process after lowering is also known (Japanese Patent Laid-Open No. 2009-235525).

JP 2009-235519 A JP 2009-235525 A

  The technique described in the above document proposes a commercially feasible technique for a method for recovering copper and gold by a wet method from sulfide ore, but improves the separation efficiency of copper and gold and improves the recovery rate of gold. There is still room for improvement.

  When wet processing sulfide sulfide ore, the accompanying gold is separated and concentrated in advance to a residue and then leached in a halogen bath, or leached in a halogen bath at the same time as the main component ore leaching. Remains a gold complex having a halide as a ligand. When the gold complex is adsorbed and recovered on activated carbon, the yield increases as the amount of adsorption increases. In particular, when the activated carbon is incinerated, the amount of adsorption per unit activated carbon weight directly affects the production cost and has a great effect. Therefore, development of a method for increasing the unit adsorption amount is desired. However, neither of Patent Documents 1 and 2 has studied the improvement of the activated carbon adsorption property of gold, and generally, the type of activated carbon and after leaching. There is a problem such as liquid contamination, and an appropriate method is not known.

  Then, this invention makes it a subject to provide the collection | recovery method of the gold | metal | money from the sulfide mineral which can increase the adsorption amount of gold | metal | money to activated carbon while improving the separation efficiency of copper and gold | metal | money.

  As a result of earnest research, the present inventor found that after gold leaching, when gold was adsorbed using activated carbon to the gold leaching solution after raising the redox potential in the gold leaching process and sufficiently leaching the gold leaching. It was found that monovalent copper ions in the liquid became a competitive adsorbate to activated carbon. And it discovered that the adsorption amount of gold | metal | money to activated carbon can be improved significantly by reducing this monovalent copper ion beforehand before the activated carbon adsorption | suction process of gold | metal | money.

In one aspect of the present invention, a first acidic aqueous solution containing chlorine ions, copper ions and iron ions and not containing bromine ions is brought into contact with sulfide ore under supply of an oxidizing agent, and the copper component in the sulfide ore is obtained. Step 2 for leaching, Step 2 for separating the leaching reaction liquid obtained in Step 1 into a leaching residue and a liquid after leaching by solid-liquid separation, and a second containing chlorine ions, bromine ions, copper ions and iron ions An acidic aqueous solution is brought into contact with the leaching residue obtained in step 2 under the supply of an oxidizing agent, and the gold component in the residue is leached, and the post-gold leaching solution obtained in step 3 is added to cuprous chloride. After adding oxidant, the redox potential (reference electrode, silver / silver chloride) is adjusted to 520 mV or more by adding an oxidizing agent to reduce monovalent copper ions in the solution after gold leaching. After the gold leaching, the gold in the liquid is activated carbon A method for recovering gold from sulphide minerals and a step 5 for adsorption.

  In one embodiment, the method for recovering gold from sulfide mineral according to the present invention includes adjusting the oxidation-reduction potential (reference electrode, silver / silver chloride) from 520 mV to 570 mV.

In another embodiment of the method for recovering gold from sulfide mineral according to the present invention, step 4 includes adjusting the oxidation-reduction potential (reference electrode, silver / silver chloride) by blowing air.

  ADVANTAGE OF THE INVENTION According to this invention, the collection | recovery method of gold | metal | money from the sulfide mineral which can increase the adsorption amount of gold | metal | money to activated carbon can be provided. Furthermore, it is possible to economically improve the separation efficiency of copper and gold by using a leachate not containing bromine ions in the copper leaching process, and use a leachate containing bromine ions in the subsequent gold leaching process. By doing so, a high gold recovery rate can be obtained.

It is a figure which shows the relationship between ORP (vs Ag / AgCl) and the leaching rate of copper and gold | metal | money. It is a graph showing the relationship between the oxidation-reduction potential of the solution after gold leaching and the gold concentration in the solution after adsorption. It is a graph showing the relationship between the oxidation-reduction potential and the change in gold concentration when CuCl is added and air is blown when the leachate is continuously supplied to the activated carbon packed column.

<Process 1: Copper leaching process>
In step 1, a leaching solution (first acidic aqueous solution) containing chlorine ions, copper ions and iron ions and not containing bromine ions is brought into contact with the sulfide mineral under the supply of an oxidizing agent, and the copper component in the sulfide mineral is then removed. Leaching. In other words, in Step 1, the copper in the sulfide ore is leached by using a chloride bath as the leaching solution, and copper ions and iron ions generally contained in the sulfide ore are present in the leaching solution. It aims to promote the leaching reaction of copper. The contact method between the leachate and the sulfide mineral is not particularly limited, and there are methods such as spraying and dipping. From the viewpoint of reaction efficiency, a method in which the sulfide mineral is immersed in the leachate and stirred is preferred. Although there is no restriction | limiting in particular as a sulfide mineral, Typically, the copper sulfide ore containing the silicate ore containing the primary copper sulfide ore containing gold | metal | money is mentioned.

  The supply source of chlorine ions is not particularly limited, and examples thereof include hydrogen chloride, hydrochloric acid, metal chloride, chlorine gas, and the like, but it is preferable to supply in the form of metal chloride in consideration of economy and safety. Examples of the metal chloride include copper chloride (cuprous chloride, cupric chloride), iron chloride (ferrous chloride, ferric chloride), and alkali metals (lithium, sodium, potassium, rubidium, cesium, francium). Chlorides and chlorides of alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, radium) can be mentioned, and sodium chloride is preferable from the viewpoint of economy and availability. Moreover, since it can utilize also as a supply source of copper ion and iron ion, it is also preferable to utilize copper chloride and iron chloride.

Copper ions and iron ions are usually supplied in the form of these salts. For example, they can be supplied in the form of halide salts. From the viewpoint that it can also be used as a supply source of chloride ions, copper ions and iron ions are preferably supplied as copper chloride and iron chloride. As copper chloride and iron chloride, it is desirable to use cupric chloride (CuCl ₂ ) and ferric chloride (FeCl ₃ ) from the viewpoint of oxidizing power, respectively, but cuprous chloride (CuCl) and ferrous chloride are preferable. Even if (FeCl ₂ ) is used, supplying an oxidizing agent to the leachate will oxidize to cupric chloride (CuCl ₂ ) and ferric chloride (FeCl ₃ ), respectively, so there is no significant difference.

  The concentration of chlorine ions in the leachate (first acidic aqueous solution) used in step 1 is preferably 70 g / L or more, and 140 g / L or more from the viewpoint of realizing a copper dissolution reaction with high efficiency. It is more preferable.

  In order to increase the leaching efficiency of copper from sulfide minerals, the leaching solution should be acidic, and since it can be used as a supply source of chloride ions, it is preferable to make it acidic with hydrochloric acid. The pH of the leaching solution is preferably about 0 to 3 and more preferably about 1.0 to 2.0 because the solubility of the leached copper is ensured. Further, the oxidation-reduction potential (reference electrode, silver / silver chloride) of the leaching solution at the start of Step 1 is preferably 500 mV or more, more preferably 550 mV or more from the viewpoint of promoting copper leaching.

  The leachate (first acidic aqueous solution) used in step 1 does not contain bromine ions. This is because if bromine ions are contained in the leaching solution, the oxidation-reduction potential at which gold leaching starts decreases, so that the overlap region where gold leaching starts while copper leaching does not proceed sufficiently increases. In other words, in the present invention, since the leaching solution (first acidic aqueous solution) used in step 1 does not contain bromine ions, the redox potential at the end point of the copper leaching step is increased while suppressing gold leaching. , Copper leaching efficiency can be increased.

  Therefore, in a preferred embodiment of the present invention, a mixed liquid of hydrochloric acid, cupric chloride, ferric chloride and sodium chloride can be used as the leachate (first acidic aqueous solution) in Step 1.

  The copper leaching step of step 1 is performed while supplying an oxidizing agent, thereby managing the redox potential. If an oxidizing agent is not added, the redox potential is lowered in the middle, and the leaching reaction does not proceed. Although there is no restriction | limiting in particular as an oxidizing agent, For example, oxygen, air, chlorine, hydrogen peroxide, etc. are mentioned. However, it is not preferable to use a bromine compound as the oxidizing agent. An oxidant with an extremely high redox potential is not necessary and air is sufficient. Air is also preferable from the viewpoint of economy and safety.

  The temperature of the leachate used in step 1 is preferably 60 ° C. or higher, more preferably 70 to 90 ° C., from the viewpoint of leaching efficiency and material of the apparatus. It is possible to carry out step 1 under pressure for the purpose of increasing the leaching efficiency, but it is sufficient under atmospheric pressure. In order to promote copper leaching, it is preferable to previously grind and grind the sulfide mineral to be treated.

Taking chalcopyrite, which is a typical copper sulfide ore, as an example, it is thought that in step 1, copper leaching occurs according to the following reaction formula.
CuFeS ₂ + 3CuCl ₂ → 4CuCl + FeCl ₂ + 2S (1)
CuFeS ₂ + 3FeCl ₃ → CuCl + 4FeCl ₂ + 2S (2)
When air is used as the oxidant, the cuprous chloride and ferrous chloride generated as a result of these leaching reactions in parallel with the progress of the reaction of formula (1) or formula (2) are as follows: In a simple reaction, they are oxidized to cupric chloride and ferric chloride, respectively.
CuCl + (1/4) O ₂ + HCl → CuCl ₂ + (1/2) H ₂ O (3)
FeCl ₂ + (1/4) O ₂ + HCl → FeCl ₃ + (1/2) H ₂ O (4)
The chemical species generated in formulas (3) and (4) can be reused for leaching as oxidants in formulas (1) and (2). As a result, the leaching rate is further increased. Since the reactions of the formulas (3) and (4) proceed with oxygen in the air blown into the leachate, cuprous chloride and cuprous chloride eluted from the raw material are blown in during the leach reaction. Copper leaching reaction can be continued using cupric chloride or ferric chloride generated by oxidizing iron.

  The leachate used in Step 1 initially has a high redox potential (reference electrode, silver / silver chloride) (eg, 500 mV or higher), but when it comes into contact with a sulfide mineral and starts the leaching reaction, the redox potential is Plummet. Thereafter, the oxidation-reduction potential gradually increases as the copper leaching reaction proceeds under the supply of the oxidizing agent. In the case of the above leaching solution not containing bromine ions, copper is sufficiently leached if the oxidation-reduction potential (reference electrode, silver / silver chloride) is 450 mV or higher. On the other hand, when the oxidation-reduction potential is increased, gold leaching starts, but in the case of the above-described leaching solution not containing bromine ions, most of the gold is present if the oxidation-reduction potential (reference electrode, silver / silver chloride) is 500 mV or less. Does not leach. Therefore, when the redox potential (reference electrode, silver / silver chloride) is in the range of 450 to 500 mV, preferably in the range of 450 to 475 mV, the copper leaching reaction in step 1 is completed, so that high separation efficiency of copper and gold can be obtained. It will be obtained.

  As a result, in a preferred embodiment of the present invention, step 1 can be completed when the leaching rate of copper is 90% by mass or more and the leaching rate of gold is 10% by mass or less, In a more preferred embodiment, Step 1 can be completed when the copper leaching rate is 95% by mass or more and the gold leaching rate is 10% by mass or less.

<Step 2: Solid-liquid separation step>
In step 2, the leaching reaction liquid obtained in step 1 is separated into a leaching residue and a liquid after leaching by solid-liquid separation. The solid-liquid separation method is not particularly limited, but a filter press or thickener can be used. Gold remains in the leaching residue, and copper is dissolved in the liquid after leaching.

In step 1, the copper leaching step can be carried out in one stage, but the copper leaching step can also be carried out in a plurality of stages in order to sufficiently leach copper in the sulfide mineral. Specifically, in the copper leaching process using multiple stages, after completing the copper leaching operation in the first stage, solid-liquid separation is performed with a filter press or thickener, and the next stage copper leaching operation is performed on the leaching residue. Can be implemented. Typically, the copper leaching process can consist of 2 to 4 stages. In this case, it carried out in the leaching stage in which the solid-liquid separation operation corresponds to step 2.

<Process 3: Gold leaching process>
In step 3, a leachate (second acidic aqueous solution) containing chlorine ions, bromine ions, copper ions and iron ions was obtained in step 2 under the supply of an oxidizing agent (step 1 was performed in multiple stages, step 2 When it is carried out a plurality of times, it is brought into contact with the leaching residue (which is finally obtained) and the gold component in the residue is leached. Gold leaching proceeds by the elution of gold reacting with chlorine ions or bromine ions to form gold chloride complexes or gold bromide complexes. By using bromine ions in combination, the complex is formed at a lower potential, so that the gold leaching efficiency can be improved. Further, the iron ions function to oxidize gold by trivalent iron ions oxidized under the supply of an oxidizing agent or trivalent iron ions from the beginning. Copper ions are not directly involved in the reaction, but the presence of copper ions increases the oxidation rate of iron ions.

  The method for contacting the leachate and the residue is not particularly limited, and there are methods such as spraying and dipping. From the viewpoint of reaction efficiency, a method in which the residue is immersed in the leachate and stirred is preferred.

  The supply source of chlorine ions is not particularly limited, and examples thereof include hydrogen chloride, hydrochloric acid, metal chloride, chlorine gas, and the like. In consideration of economy and safety, supply in the form of metal chloride is preferable. Examples of the metal chloride include copper chloride (cuprous chloride, cupric chloride), iron chloride (ferrous chloride, ferric chloride), and alkali metals (lithium, sodium, potassium, rubidium, cesium, francium). Chlorides and chlorides of alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, radium) can be mentioned, and sodium chloride is preferable from the viewpoint of economy and availability. Moreover, since it can utilize also as a supply source of copper ion and iron ion, it is also preferable to utilize copper chloride and iron chloride.

  The bromine ion supply source is not particularly limited, and examples thereof include hydrogen bromide, hydrobromic acid, metal bromide, bromine gas, and the like. In consideration of economy and safety, it is in the form of metal bromide. It is preferable to supply. Examples of the metal bromide include copper bromide (cuprous bromide, cupric bromide), iron bromide (ferrous bromide, ferric bromide), alkali metals (lithium, sodium, potassium, Examples thereof include bromides of rubidium, cesium, and francium) and bromides of alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, and radium), and sodium bromide is preferable from the viewpoint of economy and availability. Moreover, since it can utilize also as a supply source of copper ion and iron ion, it is also preferable to utilize copper bromide and iron bromide.

The supply source of copper ions and iron ions is usually supplied in the form of these salts. For example, it can be supplied in the form of a halide salt. From the viewpoint that it can also be used as a source of chlorine ions and / or bromine ions, copper ions are preferably supplied as copper chloride and / or copper bromide, and iron ions are preferably supplied as iron chloride and / or iron bromide. Although use copper and cupric (CuCl ₂₎ chloride in terms of oxidizing power as ferric chloride and ferric chloride (FeCl ₃₎ is desired, respectively, cuprous chloride (CuCl) and ferrous chloride Even if (FeCl ₂ ) is used, there is no great difference.

  The concentration of chlorine ions in the leachate (second acidic aqueous solution) used in step 3 can be 30 to 200 g / L, but may be lower than the first acidic aqueous solution, and 30 g / L to 125 g. / L may be used. The concentration of bromine ions in the leachate (second acidic aqueous solution) used in step 3 is preferably 1 g / L to 100 g / L from the viewpoint of reaction rate and solubility. Further, from the viewpoint of gold leaching efficiency, the weight concentration ratio of bromine ions to chlorine ions in the second acidic aqueous solution is preferably 1 or more, but since the gold concentration is sufficiently low, special considerations are do not need.

  The redox potential (reference electrode, silver / silver chloride) of the leaching solution at the start of Step 3 is preferably 550 mV or more, more preferably 600 mV or more, from the viewpoint of promoting gold leaching.

  Therefore, in a preferred embodiment of the present invention, at least hydrochloric acid and bromic acid are selected on the condition that the leachate (second acidic aqueous solution) in step 3 is selected to contain both chlorine ions and bromine ions. One, a mixture containing at least one of cupric chloride and cupric bromide, at least one of ferric chloride and ferric bromide, and at least one of sodium chloride and sodium bromide is used. be able to.

  The gold leaching step of step 3 is performed while supplying an oxidizing agent, thereby managing the oxidation-reduction potential. If an oxidizing agent is not added, the redox potential is lowered in the middle, and the leaching reaction does not proceed. Although there is no restriction | limiting in particular as an oxidizing agent, For example, oxygen, air, chlorine, a bromine, hydrogen peroxide, etc. are mentioned. An oxidant with an extremely high redox potential is not necessary and air is sufficient. Air is also preferable from the viewpoint of economy and safety.

<Step 4>
The oxidation-reduction potential of the solution after gold leaching after sufficient gold leaching is about 500 to 520 mV. After the gold leaching, CuCl is further added and stirred, and once the oxidation-reduction potential is lowered to 520 mV or less, more preferably 500 mV or less, an oxidizing agent is added to again adjust the ORP to 520 mV or more. As a result, monovalent copper ions in the solution after gold leaching, which inhibits the adsorption of gold by activated carbon, are oxidized and reduced to divalent copper ions, and there are fewer adsorbing competitors on the activated carbon in the solution after gold leaching. Further, the adsorption rate of gold on activated carbon is further improved.

  The oxidizing agent is not particularly limited, but air is used from the viewpoint of cost. Also, the liquid temperature is not particularly limited, but considering the fact that gold leaching is warm leaching and the aspect of oxidation efficiency, the liquid temperature of the liquid after gold leaching is preferably maintained at 45 ° C. or more, more preferably It is 50 ° C. or higher.

  An increase in ORP indicates a decrease in monovalent copper ions in the solution after gold leaching. Monovalent copper is known as a very soft element, has a high affinity for activated carbon, and competes with the adsorption of gold complexes. By reducing the monovalent copper, the adsorption active sites in the activated carbon are increased in selectivity to gold, thereby achieving efficient recovery of gold.

  By adjusting the ORP to 520 mV or more, it is possible to reduce the monovalent copper concentration in the liquid and improve the adsorption rate of gold on activated carbon. Although there is no restriction | limiting in particular in an upper limit, when the time required for adjustment and the reduction efficiency of monovalent copper are considered, it is preferable to set it as 570 mV or less, More preferably, it is preferable to adjust to 530-560 mV.

<Step 5: Gold recovery>
After the gold leaching reaction, Step 5 of recovering gold by activated carbon adsorption is performed from a gold solution obtained by solid-liquid separation. The contact of gold with activated carbon may be carried out by batch feeding or by continuously passing an acidic leachate through an adsorption tower packed with activated carbon.

  In the case of a batch type, the stirring speed is not specified. The amount of activated carbon added is 50 to 10,000 times the weight of gold.

When the particular passed through speed in a continuous flow-through scheme is not limited (typically to SV1～25) gold adsorption amount per unit weight of the activated carbon became 20000~30000g / t, activated carbon meet the required capacity Disappear. Therefore, gold strips from activated carbon and regeneration are performed based on this amount of adsorption. The method for regenerating activated carbon is carried out with a generally known sulfur compound, nitrogen compound, or acid, and is not particularly limited.

<Other processes>
(Copper recovery)
Since the liquid after leaching obtained in step 1 contains a large amount of copper component, copper can be recovered from the liquid after leaching. Although there is no restriction | limiting in particular as a copper collection | recovery method, For example, solvent extraction, ion exchange, substitution precipitation with a base metal, electrowinning, etc. can be utilized. The copper in the solution after leaching contains both monovalent and divalent states, but in order to perform solvent extraction and ion exchange smoothly, all of them should be oxidized beforehand to be divalent copper ions. Is preferred. The method of oxidation is not particularly limited, but a method of leaching air or oxygen into the liquid after leaching is simple.

<Example 1>
As the sulfide mineral, a copper concentrate containing Cu: 16% by mass, Fe: 26% by mass, S: 28% by mass and containing 63 g / t of Au was prepared. After heating 16 L of a leachate (first acidic aqueous solution) having the composition shown in Table 1 to 70 to 85 ° C., 480 g of the copper concentrate is added, and air is blown into the leachate (0.2 L / min) and stirred. The leaching test was conducted while continuing. The metal analysis was performed by ICP emission spectroscopic analysis.

＊全塩化物イオン及び全臭化物イオンは、浸出液の成分が完全に電離していると仮定し、臭素イオンは臭化ナトリウムで添加し、全塩素イオン濃度が１８０ｇ／Ｌとなるよう塩化ナトリウムで調整した。

* Total chloride and bromide ions are assumed to be completely ionized in the leachate, bromine ions are added with sodium bromide, and adjusted with sodium chloride so that the total chloride ion concentration is 180 g / L. did.

  The relationship between the oxidation-reduction potential ORP (vs Ag / AgCl) during leaching and the leaching rate of Cu and Au obtained in Example 1 is shown in Table 2 and FIG. The leaching rate was calculated by calculating backward from the content in the leaching residue, with the content in the sulfide mineral being 100%. From Table 2 and FIG. 1, Cu has no change in the leaching rate between the leaching solutions A and B, the leaching rate reaches about 90% by mass with ORP of 450 mV, and the leaching rate of 99% by mass or more with ORP of 500 mV. became. On the other hand, when the leaching solution A containing no bromine ions was used, Au hardly leached until the ORP was 450 mV, and leached at about 15% by mass at 500 mV. When the leachate B containing bromine ions was used, about 20% by mass was leached when the ORP was 450 mV, and reached about 40% by mass at 500 mV.

  In Example 1 above, solid-liquid separation between the copper leaching step and the gold leaching step is not carried out, but from the above results, using the leachate A containing no bromide ions in the copper leaching step, It can be understood that the leaching rate of gold can be increased by using the leaching solution B containing bromide ions in the gold leaching step while suppressing the leaching of gold. For example, the ORP that is the end point of the copper leaching process is set between 450 and 500 mV using the leaching liquid A, and after the solid-liquid separation, the gold leaching process is performed by switching to the leaching liquid B, thereby separating copper and gold at a high level. It can be understood that gold can be recovered at a high recovery rate while being separated with efficiency. Further, it can be seen that the copper leaching step can be completed under the conditions that the copper leaching rate is 95% by mass or more and the gold leaching rate is 10% by mass or less.

<Example 2>
In a gold leaching solution obtained after the gold leaching step using a gold leaching solution containing 50 g / L chloride ion, 80 g / L bromide ion, 18 g / L copper, and 0.2 g / L iron. Leached gold. The solution after gold leaching contained NaCl: 84 g / L, NaBr: 103 g / L, Cu: 20 g / L, Fe: 2 g / L, Au: 8 mg / L, and pH was 1.2. CuCl was added to adjust the ORP to 510 mV. After leaching, the liquid was heated to 55 ° C. and stirred while blowing 0.4 L of air per minute. This gold leaching solution was passed through a glass column filled with approximately 14 ml of coconut shell-derived activated carbon (Yaikol MC manufactured by Taihei Chemical Sangyo Co., Ltd.) to adsorb gold onto the activated carbon. The column diameter was 11 mm and the height was 150 mm. The liquid supply rate was 11.9 ml / min, and the space velocity was 50 (1 / h). Gold in the discharged solution after adsorption was diluted with hydrochloric acid and quantified by ICP-AES. The relationship between ORP and the adsorption solution after 2.

  It can be seen that the gold concentration contained in the post-adsorption liquid is significantly reduced in the liquid in which the ORP is adjusted to 520 mV or more. Although the upper limit of ORP is not set, it is understood that even if the potential is raised excessively, the gold concentration in the solution after adsorption does not drop dramatically, and it is sufficient to oxidize to at least 520 mV, but it does not prevent excessive oxidation. .

<Example 3>
In the continuously supply fluid by using a post-gold leaching solution and activated carbon packed column used in Example 2 was measured concentration of gold adsorption solution after varying the ORP by lump can added and the air blowing of CuCl . The results are shown in Figure 3.

Also from FIG. 3, the relationship between the adsorption of ORP and gold on activated carbon is clear, and gold can be recovered well when the liquid after gold leaching is contacted with activated carbon at ORP 520 mV or higher. It can also be seen that it is Cu (I) that affects the ORP.

  Cu (I) tends to be oxidized to Cu (II) in an aqueous solution, but exists relatively stably in an aqueous solution containing a relatively high concentration of halide as in the present system. Therefore, in addition to air blowing, it is estimated that similar results can be obtained by oxidizing Cu (I) with an oxidizing agent such as hydrogen peroxide or hypochlorous acid. Is preferred.

Claims (3)

Step 1 of leaching a copper component in sulfide ore by contacting a first acidic aqueous solution containing chlorine ion, copper ion and iron ion and not containing bromine ion with sulfide ore under supply of an oxidizing agent;
Step 2 for separating the leaching reaction liquid obtained in Step 1 into a leaching residue and a liquid after leaching by solid-liquid separation;
Step 3 of contacting a second acidic aqueous solution containing chlorine ion, bromine ion, copper ion and iron ion with the leaching residue obtained in Step 2 under supply of an oxidizing agent to leach the gold component in the residue When,
After adding cuprous chloride to the gold leaching solution obtained in step 3, an oxidizing agent is added to adjust the oxidation-reduction potential (reference electrode, silver / silver chloride) to 520 mV or more, and the gold leaching solution contains Step 4 for reducing monovalent copper ions;
And a step 5 of adsorbing gold in the solution after gold leaching obtained in step 4 to activated carbon, and a method for recovering gold from sulfide minerals.   The method for recovering gold from sulfide mineral according to claim 1, wherein step 4 includes adjusting the redox potential (reference electrode, silver / silver chloride) from 520 mV to 570 mV. The method for recovering gold from sulfide mineral according to claim 1 or 2, wherein step 4 includes adjusting an oxidation-reduction potential (reference electrode, silver / silver chloride) by blowing air.

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