CA2908688C - Method of recovering gold from sulfide ore - Google Patents
Method of recovering gold from sulfide ore Download PDFInfo
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- CA2908688C CA2908688C CA2908688A CA2908688A CA2908688C CA 2908688 C CA2908688 C CA 2908688C CA 2908688 A CA2908688 A CA 2908688A CA 2908688 A CA2908688 A CA 2908688A CA 2908688 C CA2908688 C CA 2908688C
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- leaching
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- chloride
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
- C22B3/24—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition by adsorption on solid substances, e.g. by extraction with solid resins
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B11/00—Obtaining noble metals
- C22B11/04—Obtaining noble metals by wet processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
Disclosed is a method of recovering gold from sulfide ores comprising: Step 1 for contacting a first acidic aqueous solution to sulfide ores with supplying an oxidizing agent to leach the copper content in the sulfide ores, said first acidic aqueous solution containing chlorine ions, copper ions and iron ions with no bromine ions; Step 2 for subjecting the leaching reaction solution thus obtained in Step 1 to solid-liquid separation to separate a leaching residue and a post-leaching solution; Step 3 for contacting a second acidic aqueous solution to said leaching residue thus obtained in Step 2 with supplying an oxidizing agent to leach the gold content in the residue, said second acidic aqueous solution containing chlorine ions, bromine ions, copper ions and iron ions; Step 4 for adding copper(I) chloride to the post-gold-leaching solution thus obtained in Step 3, and then adding an oxidizing agent to adjust the oxidation-reduction potential to 520 mV or greater, to thereby reduce monovalent copper ions in the post-gold-leaching solution; and Step 5 for adsorbing gold in the post-gold-leaching solution thus obtained in Step 4 to activated carbon.
Description
METHOD OF RECOVERING GOLD FROM SULFIDE ORE
TECHNICAL FIELD
[0001]
The present invention relates to a method of recovering gold from sulfide ore.
RELATED ART
TECHNICAL FIELD
[0001]
The present invention relates to a method of recovering gold from sulfide ore.
RELATED ART
[0002]
Recently, the technique in which copper is recovered from sulfide ores by a wet process instead of the conventional dry process has been focused. Since sulfide ores often contain noble metals such as gold even slightly, a method for recovering such noble metals such as gold in addition to copper economically is demanded.
Recently, the technique in which copper is recovered from sulfide ores by a wet process instead of the conventional dry process has been focused. Since sulfide ores often contain noble metals such as gold even slightly, a method for recovering such noble metals such as gold in addition to copper economically is demanded.
[0003]
With respect to a technique for working through such problem, a method is known to conduct a gold leaching step on the residue from a copper leaching step in which chlorides and bromides of an alkaline metal or an alkaline earth metal, and chlorides and bromides of copper and iron are used (referred to JP-A-2009-235519). In accordance with such method, copper and gold in the sulfide ores could be leached and recovered at high leaching rate merely by use of air, without using a special oxidation agent.
With respect to a technique for working through such problem, a method is known to conduct a gold leaching step on the residue from a copper leaching step in which chlorides and bromides of an alkaline metal or an alkaline earth metal, and chlorides and bromides of copper and iron are used (referred to JP-A-2009-235519). In accordance with such method, copper and gold in the sulfide ores could be leached and recovered at high leaching rate merely by use of air, without using a special oxidation agent.
[0004]
A method is also known to conduct a gold leaching step after the content of copper of residue from a copper leaching step is reduced to 7.9 % or less, since it is also know that gold is leached when the content of copper of residue from a copper leaching step reaches to 7.9 % or less (referred to JP-A-2009-235525).
PRIOR ART
PATENT LITERATURE
A method is also known to conduct a gold leaching step after the content of copper of residue from a copper leaching step is reduced to 7.9 % or less, since it is also know that gold is leached when the content of copper of residue from a copper leaching step reaches to 7.9 % or less (referred to JP-A-2009-235525).
PRIOR ART
PATENT LITERATURE
[0005]
Patent Document 1: JP-A-2009-235519 Patent Document 2: JP-A-2009-235525 SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
Patent Document 1: JP-A-2009-235519 Patent Document 2: JP-A-2009-235525 SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0006]
The above mentioned arts as described in those Patent Documents propose a commercially available technique related to a method of recovering copper and gold from sulfide ores by a wet method. There is a still room for improving the separating efficiency between copper and gold, and recovering rate of gold.
The above mentioned arts as described in those Patent Documents propose a commercially available technique related to a method of recovering copper and gold from sulfide ores by a wet method. There is a still room for improving the separating efficiency between copper and gold, and recovering rate of gold.
[0007]
In a case of wet processing sulfide ores, gold which is an accompaniment is leached with halogen bath after being separated and concentrated beforehand in the residue, or at the time in the later stage of leaching copper as a main component in halogen bath. A gold complex with a halide ligand still remains in the post-leaching solution. When recovering gold by adsorbing the gold complexes on activated carbon, the larger the adsorption amount thereof is, the larger the yield of gold should be. In particular, in the case of incineration of activated carbon, the adsorption amount per unit weight of activated carbon have a great influence directly to production costs. Therefore, although the development of a method for increasing the unit adsorption is desired, none of the Patent Documents 1 and 2 even make a consideration on increasing the adsorption amount of gold to the activated carbon.
Further, an appropriate method is still unknown in general since there are too many matter to be considered on such as the type of the activated carbon and the contaminant of the post leaching solution.
In a case of wet processing sulfide ores, gold which is an accompaniment is leached with halogen bath after being separated and concentrated beforehand in the residue, or at the time in the later stage of leaching copper as a main component in halogen bath. A gold complex with a halide ligand still remains in the post-leaching solution. When recovering gold by adsorbing the gold complexes on activated carbon, the larger the adsorption amount thereof is, the larger the yield of gold should be. In particular, in the case of incineration of activated carbon, the adsorption amount per unit weight of activated carbon have a great influence directly to production costs. Therefore, although the development of a method for increasing the unit adsorption is desired, none of the Patent Documents 1 and 2 even make a consideration on increasing the adsorption amount of gold to the activated carbon.
Further, an appropriate method is still unknown in general since there are too many matter to be considered on such as the type of the activated carbon and the contaminant of the post leaching solution.
[0008]
The present invention should intend to provide a method of recovering gold from sulfide ores in which it is possible that the separating efficiency between copper and gold should be improved and that the adsorption amount of gold to the activated carbon should be increased.
MEANS FOR SOLVING THE PROBLEM
The present invention should intend to provide a method of recovering gold from sulfide ores in which it is possible that the separating efficiency between copper and gold should be improved and that the adsorption amount of gold to the activated carbon should be increased.
MEANS FOR SOLVING THE PROBLEM
[0009]
The present inventors have conducted intensive studies, and found that, when contacting a post-gold-leaching solution, which is obtained by fully leaching gold with raising the oxidation-reduction potential in the gold leaching step, with the activated carbon to adsorb gold thereto, monovalent copper ions in the post-gold-leaching solution would be a competitive adsorption to the ak 02908688 2016-12-23 activated carbon against gold. Further, it was also found that such monovalent copper ions may be reduced before a step for adsorbing gold to the activated carbon to significantly improve the adsorption amount of gold to the activated carbon.
The present inventors have conducted intensive studies, and found that, when contacting a post-gold-leaching solution, which is obtained by fully leaching gold with raising the oxidation-reduction potential in the gold leaching step, with the activated carbon to adsorb gold thereto, monovalent copper ions in the post-gold-leaching solution would be a competitive adsorption to the ak 02908688 2016-12-23 activated carbon against gold. Further, it was also found that such monovalent copper ions may be reduced before a step for adsorbing gold to the activated carbon to significantly improve the adsorption amount of gold to the activated carbon.
[0010]
In one aspect, the present invention is a method of recovering gold from sulfide ores comprising: Step 1 for contacting a first acidic aqueous solution to sulfide ores with supplying an oxidizing agent to leach a copper content in the sulfide ores, said first acidic aqueous solution containing chlorine ions, copper ions and iron ions with no bromine ions; Step 2 for subjecting the leaching reaction resultant thus obtained in Step 1 to solid-liquid separation to separate a leaching residue and a post-leaching solution; Step 3 for contacting a second acidic aqueous solution to said leaching residue thus obtained in Step 2 with supplying an oxidizing agent to leach the gold content in the residue, said second acidic aqueous solution containing chlorine ions, bromine ions, copper ions and iron ions; Step 4 for adding copper(I) chloride to the post-gold-leaching solution thus obtained in Step 3, and then adding an oxidizing agent to adjust the oxidation-reaction potential (reference electrode: silver/silver chloride) to 520 mV or greater, to thereby reduce the amount of monovalent copper ions in the post-gold-leaching solution; and Step 5 for adsorbing gold in the post-gold-leaching solution thus obtained in Step 4 to activated carbon.
In one aspect, the present invention is a method of recovering gold from sulfide ores comprising: Step 1 for contacting a first acidic aqueous solution to sulfide ores with supplying an oxidizing agent to leach a copper content in the sulfide ores, said first acidic aqueous solution containing chlorine ions, copper ions and iron ions with no bromine ions; Step 2 for subjecting the leaching reaction resultant thus obtained in Step 1 to solid-liquid separation to separate a leaching residue and a post-leaching solution; Step 3 for contacting a second acidic aqueous solution to said leaching residue thus obtained in Step 2 with supplying an oxidizing agent to leach the gold content in the residue, said second acidic aqueous solution containing chlorine ions, bromine ions, copper ions and iron ions; Step 4 for adding copper(I) chloride to the post-gold-leaching solution thus obtained in Step 3, and then adding an oxidizing agent to adjust the oxidation-reaction potential (reference electrode: silver/silver chloride) to 520 mV or greater, to thereby reduce the amount of monovalent copper ions in the post-gold-leaching solution; and Step 5 for adsorbing gold in the post-gold-leaching solution thus obtained in Step 4 to activated carbon.
[0011]
In one embodiment of the method of recovering gold from sulfide ores according to the present invention, the Step 4 comprises adjusting the oxidation-reduction potential (reference electrode: silver/silver chloride) to 520 mV to 570 mV.
In one embodiment of the method of recovering gold from sulfide ores according to the present invention, the Step 4 comprises adjusting the oxidation-reduction potential (reference electrode: silver/silver chloride) to 520 mV to 570 mV.
[0012]
In another embodiment of the method of recovering gold from sulfide ores according to the prensent invention, the Step 4 comprises the oxidation-reduction potential is adjusted by blowing air.
EFFECT OF THE INVENTION
In another embodiment of the method of recovering gold from sulfide ores according to the prensent invention, the Step 4 comprises the oxidation-reduction potential is adjusted by blowing air.
EFFECT OF THE INVENTION
[0013]
The present invention may provide a method of recovering gold from sulfide ores in which it is possible that that the adsorption amount of gold to the activated carbon should be increased. Further, the separating efficiency between copper and gold should be improved by employing in a copper leaching step a leaching liquid which does not contain bromine ions. Moreover, a high gold leaching rate is realized by employing in subsequent gold leaching step a leaching liquid which contains bromine ions.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may provide a method of recovering gold from sulfide ores in which it is possible that that the adsorption amount of gold to the activated carbon should be increased. Further, the separating efficiency between copper and gold should be improved by employing in a copper leaching step a leaching liquid which does not contain bromine ions. Moreover, a high gold leaching rate is realized by employing in subsequent gold leaching step a leaching liquid which contains bromine ions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a drawing illustrating a relationship between ORP
(vs Ag/AgC1) and leaching rates of copper and gold;
FIG. 2 is a graph illustrating a relationship between the oxidation-reduction potential of the post-gold-leaching solution and the gold concentration in the post-adsorption solution; and FIG. 3 is a graph illustrating a relationship between changes in the oxidation-reduction potential and the gold concentration, provided that the leaching solution is continuously fed into a column filled with an activated carbon and that adding CuCl and flowing air is conducted.
MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a drawing illustrating a relationship between ORP
(vs Ag/AgC1) and leaching rates of copper and gold;
FIG. 2 is a graph illustrating a relationship between the oxidation-reduction potential of the post-gold-leaching solution and the gold concentration in the post-adsorption solution; and FIG. 3 is a graph illustrating a relationship between changes in the oxidation-reduction potential and the gold concentration, provided that the leaching solution is continuously fed into a column filled with an activated carbon and that adding CuCl and flowing air is conducted.
MODE FOR CARRYING OUT THE INVENTION
[0015]
<Step 1: Copper leaching step>
In Step 1, a leaching liquid (a first acidic aqueous solution) which contains chlorine ions, copper ions and iron ions with no bromine ions is contacted to sulfide ores with supplying an oxidizing agent to leach the copper content in the sulfide ores. That is, in Step 1, it is based on the fact that sulfide ores is leached by using a chloride bath as a leaching liquid.
Further, copper ions and iron ions generally included in sulfide ores is allowed to be present in the leaching liquid, so that it is intended to promote copper leaching reaction. There is no special limitation of a manner for contacting the leaching liquid with the sulfide ores, such as spraying and dipping the sulfide ores. From the viewpoint of reaction efficiency, it is preferable to dip the sulfide ores in the leaching liquid and to stir it.
Such sulfide ores include, without special limitation, typically a primary copper-sulfide ore containing gold and a copper-sulfide ore containing silicate ore containing gold.
<Step 1: Copper leaching step>
In Step 1, a leaching liquid (a first acidic aqueous solution) which contains chlorine ions, copper ions and iron ions with no bromine ions is contacted to sulfide ores with supplying an oxidizing agent to leach the copper content in the sulfide ores. That is, in Step 1, it is based on the fact that sulfide ores is leached by using a chloride bath as a leaching liquid.
Further, copper ions and iron ions generally included in sulfide ores is allowed to be present in the leaching liquid, so that it is intended to promote copper leaching reaction. There is no special limitation of a manner for contacting the leaching liquid with the sulfide ores, such as spraying and dipping the sulfide ores. From the viewpoint of reaction efficiency, it is preferable to dip the sulfide ores in the leaching liquid and to stir it.
Such sulfide ores include, without special limitation, typically a primary copper-sulfide ore containing gold and a copper-sulfide ore containing silicate ore containing gold.
[0016]
A source of supply for chlorine ions includes, without special limitation, hydrogen chloride, hydrochloric acid, metal chloride and chlorine gas. From the viewpoint of economy and safety, chlorine ions is preferably supplied in a form of metal chloride. Such metal chloride includes, for instance, copper chloride (copper(I) chloride, copper(II) chloride), and iron chloride (iron(I) chloride, iron(II) chloride), and a chloride of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a chloride of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium chloride is preferable. Copper chloride and iron chloride are also preferable since those chlorides may be used as a source of supply for copper ions and iron ions.
A source of supply for chlorine ions includes, without special limitation, hydrogen chloride, hydrochloric acid, metal chloride and chlorine gas. From the viewpoint of economy and safety, chlorine ions is preferably supplied in a form of metal chloride. Such metal chloride includes, for instance, copper chloride (copper(I) chloride, copper(II) chloride), and iron chloride (iron(I) chloride, iron(II) chloride), and a chloride of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a chloride of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium chloride is preferable. Copper chloride and iron chloride are also preferable since those chlorides may be used as a source of supply for copper ions and iron ions.
[0017]
Copper ions and iron ions are supplied usually in a form of salt, and for example may be supplied in a form of a halogenated salt. Copper ions and iron ions may be also supplied in a form of copper chloride and iron chloride, since they also could be used as a source of supply for chloride ions. It is preferable to use copper(II) chloride (CuC12) and iron(II) chloride (FeCl3) as such a copper chloride and iron chloride, respectively, from the viewpoint of oxidizability. However, copper(I) chloride (CuCl) and iron(I) chloride (FeCl2) may also be used with supplying an oxidizing agent to be oxidized to copper(II) chloride (CuC12) and iron(II) chloride (FeC13), reepectivey, so that it does not make much difference.
Copper ions and iron ions are supplied usually in a form of salt, and for example may be supplied in a form of a halogenated salt. Copper ions and iron ions may be also supplied in a form of copper chloride and iron chloride, since they also could be used as a source of supply for chloride ions. It is preferable to use copper(II) chloride (CuC12) and iron(II) chloride (FeCl3) as such a copper chloride and iron chloride, respectively, from the viewpoint of oxidizability. However, copper(I) chloride (CuCl) and iron(I) chloride (FeCl2) may also be used with supplying an oxidizing agent to be oxidized to copper(II) chloride (CuC12) and iron(II) chloride (FeC13), reepectivey, so that it does not make much difference.
[0018]
The chloride ion concentration in the leaching liquid as used in Step 1 (the first acidic aqueous solution) is preferably 70 g/L or greater, more preferably 140 g/L or greater, from the viewpoint of realizing copper dissolving reaction with high efficiency.
The chloride ion concentration in the leaching liquid as used in Step 1 (the first acidic aqueous solution) is preferably 70 g/L or greater, more preferably 140 g/L or greater, from the viewpoint of realizing copper dissolving reaction with high efficiency.
[0019]
The leaching liquid should be acidic if the leaching efficiency of copper from sulfide ores is intended to be high, so that the liquid may be preferably hydrochloric acid acidic. Such liquid may also be used as a source of supply for chloride ions.
The pH of the leaching liquid is preferably about 0 to 3, more preferably about 1.0 to 2.0, since the solubility of the leached copper is intended to be ensured. Further, the oxidation-reduction potential (reference electrode: silver/silver chloride) of the leaching liquid at starting Step 1 is preferably 500 mV or greater, more preferably 550 mV or greater, from the viewpoint of promoting copper leaching.
The leaching liquid should be acidic if the leaching efficiency of copper from sulfide ores is intended to be high, so that the liquid may be preferably hydrochloric acid acidic. Such liquid may also be used as a source of supply for chloride ions.
The pH of the leaching liquid is preferably about 0 to 3, more preferably about 1.0 to 2.0, since the solubility of the leached copper is intended to be ensured. Further, the oxidation-reduction potential (reference electrode: silver/silver chloride) of the leaching liquid at starting Step 1 is preferably 500 mV or greater, more preferably 550 mV or greater, from the viewpoint of promoting copper leaching.
[0020]
The leaching liquid (the first acidic aqueous solution) as used in Step 1 does not contain bromine ions. If bromine ions are included in the leaching liquid, the oxidation-reduction potential of starting gold leaching is lowered, so that the range in which the copper leaching is not fully progressed and the gold leaching gets started, "the overlapping range", would be enlarged. That is, in the invention, bromine ions are not included in the leaching liquid (the first acidic aqueous solution) as used in Step 1, so that while suppressing the leaching of gold, the oxidation-reduction potential at the end of the copper leaching step may be raised to increase the leaching efficiency of copper.
The leaching liquid (the first acidic aqueous solution) as used in Step 1 does not contain bromine ions. If bromine ions are included in the leaching liquid, the oxidation-reduction potential of starting gold leaching is lowered, so that the range in which the copper leaching is not fully progressed and the gold leaching gets started, "the overlapping range", would be enlarged. That is, in the invention, bromine ions are not included in the leaching liquid (the first acidic aqueous solution) as used in Step 1, so that while suppressing the leaching of gold, the oxidation-reduction potential at the end of the copper leaching step may be raised to increase the leaching efficiency of copper.
[0021]
Accordingly, in a suitable embodiment of the invention, a mixture of hydrochloric acid, copper(II) chloride, iron(II) chloride and sodium chloride may be used as a leaching liquid of Step 1 (a first acidic aqueous solution).
Accordingly, in a suitable embodiment of the invention, a mixture of hydrochloric acid, copper(II) chloride, iron(II) chloride and sodium chloride may be used as a leaching liquid of Step 1 (a first acidic aqueous solution).
[0022]
The copper leaching step of Step 1 is conducted with supplying an oxidizing agent to manage the oxidation-reduction potential. If the oxidizing agent is not added, the oxidation-reduction potential gets lower in the middle of the copper leaching step, so that the leaching reaction is not progressed.
Such oxidizing agent includes, without special limitation, oxygen, air, chlorine and hydrogen peroxide. It is not preferable to use a bromine compound as an oxidizing agent. An oxidizing agent having the extremely high oxidation-reduction potential is not needed, and air should be sufficient. Further, even air is preferable from the viewpoint of economy and safety.
The copper leaching step of Step 1 is conducted with supplying an oxidizing agent to manage the oxidation-reduction potential. If the oxidizing agent is not added, the oxidation-reduction potential gets lower in the middle of the copper leaching step, so that the leaching reaction is not progressed.
Such oxidizing agent includes, without special limitation, oxygen, air, chlorine and hydrogen peroxide. It is not preferable to use a bromine compound as an oxidizing agent. An oxidizing agent having the extremely high oxidation-reduction potential is not needed, and air should be sufficient. Further, even air is preferable from the viewpoint of economy and safety.
[0023]
The temperature of the leaching liquid used in Step 1 is preferably 60 degrees C or higher, and more preferably 70 to 90 degrees C, from the viewpoint of the leaching efficiency and the material of apparatus. It is possible to conduct Step 1 under pressure for the purpose of raising the leaching efficiency, and however atmospheric pressure should be sufficient. Further, it is preferable to pulverize and grind sulfide ores to be subjected to the process in advance in order to promote copper leaching.
The temperature of the leaching liquid used in Step 1 is preferably 60 degrees C or higher, and more preferably 70 to 90 degrees C, from the viewpoint of the leaching efficiency and the material of apparatus. It is possible to conduct Step 1 under pressure for the purpose of raising the leaching efficiency, and however atmospheric pressure should be sufficient. Further, it is preferable to pulverize and grind sulfide ores to be subjected to the process in advance in order to promote copper leaching.
[0024]
Referring to chalcopyrite as a representative example for a copper sulfide ores, it is considered that the copper leaching may be conducted in accordance with the following reaction formula in Step 1:
CuFeS2 + 3CuC12 4CuCl + FeC12 + 2S (1) CuFeS2 + 3FeC13 CuCl + 4FeC12 + 2S (2).
When using air as an oxidizing agent, the reactions of (1) and (2) are progressed, and in parallel with those reaction copper(I) chloride and iron(I) chloride resulting the above leaching reactions are oxidized to copper(II) chloride and iron(II) chloride, respectively, under the following reaction:
CuCl + (1/4)02 + HC1 0u012 + (1/2) H20 (3) FeC12 + (1/4)02 + HC1 FeCl3 + (1/2)H20 (4).
The chemical species being produced in (3) and (4) may be re-used in the leaching in (1) and (2) as an oxidizing agent.
Since the reactions of (3) and (4) is progressed with oxygen in the air which is blown into the leaching liquid, the copper leaching reaction may be continued by use of copper(II) chloride and iron(II) chloride, which are produced by oxidizing copper(I) chloride and iron(I) chloride being eluted from the starting material by blowing air during the leaching reaction.
Referring to chalcopyrite as a representative example for a copper sulfide ores, it is considered that the copper leaching may be conducted in accordance with the following reaction formula in Step 1:
CuFeS2 + 3CuC12 4CuCl + FeC12 + 2S (1) CuFeS2 + 3FeC13 CuCl + 4FeC12 + 2S (2).
When using air as an oxidizing agent, the reactions of (1) and (2) are progressed, and in parallel with those reaction copper(I) chloride and iron(I) chloride resulting the above leaching reactions are oxidized to copper(II) chloride and iron(II) chloride, respectively, under the following reaction:
CuCl + (1/4)02 + HC1 0u012 + (1/2) H20 (3) FeC12 + (1/4)02 + HC1 FeCl3 + (1/2)H20 (4).
The chemical species being produced in (3) and (4) may be re-used in the leaching in (1) and (2) as an oxidizing agent.
Since the reactions of (3) and (4) is progressed with oxygen in the air which is blown into the leaching liquid, the copper leaching reaction may be continued by use of copper(II) chloride and iron(II) chloride, which are produced by oxidizing copper(I) chloride and iron(I) chloride being eluted from the starting material by blowing air during the leaching reaction.
[0025]
The leaching luquid used in Step 1 has a high oxidation-reduction potential (reference electrode: silver/silver chloride) initially. However, when the leaching reaction is started by contacting the liquid with sulfide ores, the oxidation-reduction potential drops. Thereafter, the oxidation-reduction potential gradually increases as the copper leaching reaction is progressed under supplying an oxidizing agent. In a case of using a leaching liquid having no bromine ions, copper is fully leached as the oxidation-reduction potential (reference electrode: silver/silver chloride) is 450 mV or greater. On the other hand, when the oxidation-reduction potential becomes high, it is considered that gold leaching may now start. However, in a case of using a leaching liquid having no bromine ions, gold is leached so little as the oxidation-reduction potential (reference electrode:
silver/silver chloride) is 500 mV or less. Therefore, the copper leaching reaction of Step 1 is terminated when the oxidation-reduction potential (reference electrode: silver/silver chloride) is in the range of 450 to 500 mV, preferably 450 to 475 mV, so that high separating efficiency between copper and gold may be realized.
The leaching luquid used in Step 1 has a high oxidation-reduction potential (reference electrode: silver/silver chloride) initially. However, when the leaching reaction is started by contacting the liquid with sulfide ores, the oxidation-reduction potential drops. Thereafter, the oxidation-reduction potential gradually increases as the copper leaching reaction is progressed under supplying an oxidizing agent. In a case of using a leaching liquid having no bromine ions, copper is fully leached as the oxidation-reduction potential (reference electrode: silver/silver chloride) is 450 mV or greater. On the other hand, when the oxidation-reduction potential becomes high, it is considered that gold leaching may now start. However, in a case of using a leaching liquid having no bromine ions, gold is leached so little as the oxidation-reduction potential (reference electrode:
silver/silver chloride) is 500 mV or less. Therefore, the copper leaching reaction of Step 1 is terminated when the oxidation-reduction potential (reference electrode: silver/silver chloride) is in the range of 450 to 500 mV, preferably 450 to 475 mV, so that high separating efficiency between copper and gold may be realized.
[0026]
As a result, in a preferable embodiment of the invention, Step 1 may be terminated when the condition of the copper leaching rate of 90 mass% or greater and the gold leaching rate of 10 mass%
or less is satisfied. In a more preferable embodiment, Step 1 may be terminated when the condition of the copper leaching rate of 95 mass% or greater and the gold leaching rate of 10 mass% or less is satisfied.
As a result, in a preferable embodiment of the invention, Step 1 may be terminated when the condition of the copper leaching rate of 90 mass% or greater and the gold leaching rate of 10 mass%
or less is satisfied. In a more preferable embodiment, Step 1 may be terminated when the condition of the copper leaching rate of 95 mass% or greater and the gold leaching rate of 10 mass% or less is satisfied.
[0027]
<Step 2: Solid-liquid separation step>
In Step 2, the leaching reaction solution thus obtained in Step 1 is subjected to solid-liquid separation to separate a leaching residue and a post-leaching solution. With respect to the solid-liquid separation, without special limitation, filter press or thickener may be employed. Gold remains in the leaching residue, and copper is dissolved in the post-leaching solution.
<Step 2: Solid-liquid separation step>
In Step 2, the leaching reaction solution thus obtained in Step 1 is subjected to solid-liquid separation to separate a leaching residue and a post-leaching solution. With respect to the solid-liquid separation, without special limitation, filter press or thickener may be employed. Gold remains in the leaching residue, and copper is dissolved in the post-leaching solution.
[0028]
In Step 1, the copper leaching step may be conducted via a single-stage. Further, it is also possible to conduct the copper leaching step via a multi-stage in order to fully leach copper from sulfide ores. The copper leaching step via a multi-stage may be conducted, in which the solid-liquid separation is conducted by use of filter press or thickener after the completion of the copper leaching procedure for the first stage, and the subsequent stage of the copper leaching procedure may be conducted on the resulting leaching residue from the first stage. Typically, the copper leaching step may be composed of two to four stages. In such case, the solid-liquid separation as conduced in each stage of the leaching should correspond to Step 2.
In Step 1, the copper leaching step may be conducted via a single-stage. Further, it is also possible to conduct the copper leaching step via a multi-stage in order to fully leach copper from sulfide ores. The copper leaching step via a multi-stage may be conducted, in which the solid-liquid separation is conducted by use of filter press or thickener after the completion of the copper leaching procedure for the first stage, and the subsequent stage of the copper leaching procedure may be conducted on the resulting leaching residue from the first stage. Typically, the copper leaching step may be composed of two to four stages. In such case, the solid-liquid separation as conduced in each stage of the leaching should correspond to Step 2.
[0029]
<Step 3: Gold leaching step>
In Step 3, a leaching liquid (a second acidic aqueous solution) which contains chlorine ions, bromine ions, copper ions and iron ions is contacted to the resulting leaching residue from Step 2 (when conducting Step 1 via a multi-stage and conducting Step 2 for a plural of times, the residue would be the one obtained at the last stage) with supplying an oxidizing agent to leach the gold content in the residue. Gold leaching is propressed by reacting the leached gold with chlorine ions or bromine ions to generate a chloride complex of gold or a bromide complex of gold.
Using bromine ions together, the complex may be generated at lower potential, so that the gold leaching efficiency may be improved.
Further, with respect to iron ions, trivalent iron ions formed by being oxidized with the supply for an oxidizing agent or ions being originally trivalent would serve to oxidize gold. Although copper ions do not involve the reaction directly, the rate of oxidation by iron ions may be faster in the presence of copper ions.
<Step 3: Gold leaching step>
In Step 3, a leaching liquid (a second acidic aqueous solution) which contains chlorine ions, bromine ions, copper ions and iron ions is contacted to the resulting leaching residue from Step 2 (when conducting Step 1 via a multi-stage and conducting Step 2 for a plural of times, the residue would be the one obtained at the last stage) with supplying an oxidizing agent to leach the gold content in the residue. Gold leaching is propressed by reacting the leached gold with chlorine ions or bromine ions to generate a chloride complex of gold or a bromide complex of gold.
Using bromine ions together, the complex may be generated at lower potential, so that the gold leaching efficiency may be improved.
Further, with respect to iron ions, trivalent iron ions formed by being oxidized with the supply for an oxidizing agent or ions being originally trivalent would serve to oxidize gold. Although copper ions do not involve the reaction directly, the rate of oxidation by iron ions may be faster in the presence of copper ions.
[0030]
A manner of contacting the residue with the leaching solution includes, without special limitation, spraying and dipping. From the viewpoint of the reaction efficiency, it is preferable to dip the residue in the leaching liquid and to stir it.
A manner of contacting the residue with the leaching solution includes, without special limitation, spraying and dipping. From the viewpoint of the reaction efficiency, it is preferable to dip the residue in the leaching liquid and to stir it.
[0031]
A source of supply for chlorine ions includes, without special limitation, hydrogen chloride, hydrochloric acid, metal chloride and chlorine gas. From the viewpoint of economy and safety, chlorine ions is preferably supplied in a form of metal chloride. Such metal chloride includes, for instance, copper chloride (copper(I) chloride, copper(II) chloride), and iron chloride (iron(I) chloride, iron(II) chloride), and a chloride of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a chloride of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium chloride is preferable. Copper chloride and iron chloride are also preferable since those chlorides may be used as a source of supply for copper ions and iron ions.
A source of supply for chlorine ions includes, without special limitation, hydrogen chloride, hydrochloric acid, metal chloride and chlorine gas. From the viewpoint of economy and safety, chlorine ions is preferably supplied in a form of metal chloride. Such metal chloride includes, for instance, copper chloride (copper(I) chloride, copper(II) chloride), and iron chloride (iron(I) chloride, iron(II) chloride), and a chloride of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a chloride of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium chloride is preferable. Copper chloride and iron chloride are also preferable since those chlorides may be used as a source of supply for copper ions and iron ions.
[0032]
A source of supply for bromine ions includes, without special limitation, hydrogen bromide, hydrobromic acid, metal bromide and bromine. From the viewpoint of economy and safety, bromine ions is preferably supplied in a form of metal bromide.
Such metal bromide includes, for instance, copper bromide (copper(I) bromide, copper(II) bromide), and iron bromide (iron(I) bromide, iron(II) bromide), and a bromide of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a bromide of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium bromide is preferable. Copper bromide and iron bromide are also preferable since those bromides may be used as a source of supply for copper ions and iron ions.
A source of supply for bromine ions includes, without special limitation, hydrogen bromide, hydrobromic acid, metal bromide and bromine. From the viewpoint of economy and safety, bromine ions is preferably supplied in a form of metal bromide.
Such metal bromide includes, for instance, copper bromide (copper(I) bromide, copper(II) bromide), and iron bromide (iron(I) bromide, iron(II) bromide), and a bromide of alkaline metal such as lithium, sodium, potassium, rubidium, cesium, francium, and a bromide of alkaline earth metal such as beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of economy and availability, sodium bromide is preferable. Copper bromide and iron bromide are also preferable since those bromides may be used as a source of supply for copper ions and iron ions.
[0033]
A source of copper ions and iron ions is usually in a form of salt, and for example may be supplied in a form of a halogenated salt. Copper ions is preferably supplied in a form of copper chloride and/or copper bromide, and iron ions is preferably supplied in a form of iron chloride and/or iron bromide, from the viewpoint which they also could be used as a source of supply for chloride ions and/or bromide ions. It is preferable to use copper(II) chloride (CuC12) and iron(II) chloride (FeCl3) as such a copper chloride and iron chloride, respectively, from the viewpoint of oxidizability. However, it does not make much difference to use copper(I) chloride (CuCl) and iron(I) chloride (FeCl2)
A source of copper ions and iron ions is usually in a form of salt, and for example may be supplied in a form of a halogenated salt. Copper ions is preferably supplied in a form of copper chloride and/or copper bromide, and iron ions is preferably supplied in a form of iron chloride and/or iron bromide, from the viewpoint which they also could be used as a source of supply for chloride ions and/or bromide ions. It is preferable to use copper(II) chloride (CuC12) and iron(II) chloride (FeCl3) as such a copper chloride and iron chloride, respectively, from the viewpoint of oxidizability. However, it does not make much difference to use copper(I) chloride (CuCl) and iron(I) chloride (FeCl2)
[0034]
The chlorine ion concentration in the leaching liquid as used in Step 3 (the second acidic aqueous solution) may be 30 to 200 g/L, and may be lower than that of the first acidic aqueous solution, such as 30 g/L to 125 g/L. The bromine ion concentration in the leaching liquid as used in Step 3 (the second acidic aqueous solution) is preferably 1 g/L to 100 g/L from the viewpoint of reaction rate and solubility. Further, from the viewpoint of the gold leaching efficiency, the ratio of mass concentration of bromine ions to chlorine ions in the second acidic aqueous solution is preferably 1 or greater. However, since the concentration of gold is sufficiently small, special consideration shall not be required.
The chlorine ion concentration in the leaching liquid as used in Step 3 (the second acidic aqueous solution) may be 30 to 200 g/L, and may be lower than that of the first acidic aqueous solution, such as 30 g/L to 125 g/L. The bromine ion concentration in the leaching liquid as used in Step 3 (the second acidic aqueous solution) is preferably 1 g/L to 100 g/L from the viewpoint of reaction rate and solubility. Further, from the viewpoint of the gold leaching efficiency, the ratio of mass concentration of bromine ions to chlorine ions in the second acidic aqueous solution is preferably 1 or greater. However, since the concentration of gold is sufficiently small, special consideration shall not be required.
[0035]
The oxidation-reduction potential (reference electrode:
silver/silver chloride) of the leaching liquid at starting Step 3 is preferably 550 mV or greater, more preferably 600 mV or greater from the viewpoint of promoting gold leaching.
The oxidation-reduction potential (reference electrode:
silver/silver chloride) of the leaching liquid at starting Step 3 is preferably 550 mV or greater, more preferably 600 mV or greater from the viewpoint of promoting gold leaching.
[0036]
Accordingly, in a suitable embodiment of the invention, a mixture of at least one of hydrochloric acid and hydrobromic acid, and at least one of copper(II) chloride and copper(II) bromide, and at least one of iron(II) chloride and iron(II) bromide, and at least one of sodium chloride and sodium bromide may be used as a leaching liquid of Step 3 (a second acidic aqueous solution), as far as both of chloride ions and bromide ions are included therein.
Accordingly, in a suitable embodiment of the invention, a mixture of at least one of hydrochloric acid and hydrobromic acid, and at least one of copper(II) chloride and copper(II) bromide, and at least one of iron(II) chloride and iron(II) bromide, and at least one of sodium chloride and sodium bromide may be used as a leaching liquid of Step 3 (a second acidic aqueous solution), as far as both of chloride ions and bromide ions are included therein.
[0037]
The gold leaching step of Step 3 is conducted with supplying an oxidizing agent to manage the oxidation-reduction potential. If the oxidizing agent is not added, the oxidation-reduction potential gets lower in the middle of the gold leaching step, so that the leaching reaction is not progressed. Such oxidizing agent includes, without special limitation, oxygen, air, chlorine, bromine and hydrogen peroxide. An oxidizing agent having the extremely high oxidation-reduction potential is not needed, and air should be sufficient. Further, even air is preferable from the viewpoint of economy and safety.
The gold leaching step of Step 3 is conducted with supplying an oxidizing agent to manage the oxidation-reduction potential. If the oxidizing agent is not added, the oxidation-reduction potential gets lower in the middle of the gold leaching step, so that the leaching reaction is not progressed. Such oxidizing agent includes, without special limitation, oxygen, air, chlorine, bromine and hydrogen peroxide. An oxidizing agent having the extremely high oxidation-reduction potential is not needed, and air should be sufficient. Further, even air is preferable from the viewpoint of economy and safety.
[0038]
<Step 4>
The oxidation-reduction potential of the post-gold-leaching solution obtained after the gold leaching is fully conducted is appropriately 500 to 520 mV. CuCl is further added to the post-gold-leaching solution and stir it to reduce the oxidation-reduction potential to 520 mV or less, preferably 500 mV or less, and then an oxidizing agent is added to re-adjust the ORP to 520 mV or greater. As a result, monovalent copper ions in the post-gold-leaching solution, which inhibits the adsorption of gold to the activated carbon, is oxidized to divalent copper ions to reduce the amount of monovalent copper, so that the amount of competitive adsorption to the activated carbon in the post-gold-leaching solution. Accordingly, the adsorption rate of gold on the activated carbon is improved.
<Step 4>
The oxidation-reduction potential of the post-gold-leaching solution obtained after the gold leaching is fully conducted is appropriately 500 to 520 mV. CuCl is further added to the post-gold-leaching solution and stir it to reduce the oxidation-reduction potential to 520 mV or less, preferably 500 mV or less, and then an oxidizing agent is added to re-adjust the ORP to 520 mV or greater. As a result, monovalent copper ions in the post-gold-leaching solution, which inhibits the adsorption of gold to the activated carbon, is oxidized to divalent copper ions to reduce the amount of monovalent copper, so that the amount of competitive adsorption to the activated carbon in the post-gold-leaching solution. Accordingly, the adsorption rate of gold on the activated carbon is improved.
[0039]
For the oxidizing agent, without special limitation, air is used from the viewpoint of cost. Further, for the solution temperature, without special limitation, from the viewpoint that the gold leaching is a heat-leaching, and the viewpoint of the oxidation efficiency, it is preferable to keep the solution temperature of the post-gold-leaching solution at 45 degrees C or higher, more preferable 50 degrees C or higher.
For the oxidizing agent, without special limitation, air is used from the viewpoint of cost. Further, for the solution temperature, without special limitation, from the viewpoint that the gold leaching is a heat-leaching, and the viewpoint of the oxidation efficiency, it is preferable to keep the solution temperature of the post-gold-leaching solution at 45 degrees C or higher, more preferable 50 degrees C or higher.
[0040]
The increase of the ORP indicates reducing the amount of monovalent copper in the post-gold-leaching solution. Monovalent copper is known as a quite soft element, so that it has high affinity for the activated carbon, and then compete against a gold complex in the adsorption to the activated carbon. By redusing the amount of the monovalent copper, the activated sites for the adsorption in the activated carbon will open to gold, so that the selectivity by gold increases, and the effective recovery of gold is achieved.
The increase of the ORP indicates reducing the amount of monovalent copper in the post-gold-leaching solution. Monovalent copper is known as a quite soft element, so that it has high affinity for the activated carbon, and then compete against a gold complex in the adsorption to the activated carbon. By redusing the amount of the monovalent copper, the activated sites for the adsorption in the activated carbon will open to gold, so that the selectivity by gold increases, and the effective recovery of gold is achieved.
[0041]
By adjusting the ORP to 520 mV or greater, the concetration of the monovalent copper is reduced, so that the adsorption rate of gold to the actiated carbon may be improved. For the upper limit of the ORP, without special limitation, from the viewpoint of a period requried to adjust the ORP and reduction efficiency of the amount of monovalent copper, the ORP is adjusted preferably to 570 mV or less, more preferably to 530 to 560 mV.
By adjusting the ORP to 520 mV or greater, the concetration of the monovalent copper is reduced, so that the adsorption rate of gold to the actiated carbon may be improved. For the upper limit of the ORP, without special limitation, from the viewpoint of a period requried to adjust the ORP and reduction efficiency of the amount of monovalent copper, the ORP is adjusted preferably to 570 mV or less, more preferably to 530 to 560 mV.
[0042]
<Step 5: Gold recovery>
Step 5 is conducted for recovering gold by adsorption to the activated carbon from the gold solution obtained by the solid-liquid separation after the gold leaching reaction. The contact of gold to the activated carbon may be conducted by batchwise manner, or continuous eluting the acidic leaching solution on the adsorption column filled with the activated carbon.
<Step 5: Gold recovery>
Step 5 is conducted for recovering gold by adsorption to the activated carbon from the gold solution obtained by the solid-liquid separation after the gold leaching reaction. The contact of gold to the activated carbon may be conducted by batchwise manner, or continuous eluting the acidic leaching solution on the adsorption column filled with the activated carbon.
[0043]
In case of batchwise manner, the stirring rate is not designed. The activated carbon is filled to the amount of 50 times to 10000 times of the mass amount of gold.
In case of batchwise manner, the stirring rate is not designed. The activated carbon is filled to the amount of 50 times to 10000 times of the mass amount of gold.
[0044]
In case of continuous eluting, elution rate is not limited (in general, SV 1 to 25). On the other hand, when the amount of gold adsorption at a unit mass of the activated carbon reaches 20000 to 30000 g/t, such activated carbon does not meet the required capability. Therefore, strip of gold from the activated carbon or recovering is conducted based on the above mentioned amount of gold adsorption. Recovering the activated carbon is conducted by, without special limitation, well know method with sulfur compound, nitrogen compound or oxygen.
In case of continuous eluting, elution rate is not limited (in general, SV 1 to 25). On the other hand, when the amount of gold adsorption at a unit mass of the activated carbon reaches 20000 to 30000 g/t, such activated carbon does not meet the required capability. Therefore, strip of gold from the activated carbon or recovering is conducted based on the above mentioned amount of gold adsorption. Recovering the activated carbon is conducted by, without special limitation, well know method with sulfur compound, nitrogen compound or oxygen.
[0045]
<Other step>
(Recovering copper) Since the post-leaching solution from Step 1 contains copper content in a large amount, copper may be recovered from such post-leaching solution. A manner for recovering copper includes, without special limitation, solvent extraction, ion exchange, displacement deposition with base metals and electrowinning. The post-leaching solution contains copper as mixture of a form of both of monovalent and divalent, so that oxidation may be preferably conducted, and then all should be divalent copper ions in order to facilitate the solvent extraction and the ion exchange. For a manner for oxidation, without special limitation, a manner that air or oxygen is blown into the post-leaching solution is easy-to-use.
EXAMPLES
<Other step>
(Recovering copper) Since the post-leaching solution from Step 1 contains copper content in a large amount, copper may be recovered from such post-leaching solution. A manner for recovering copper includes, without special limitation, solvent extraction, ion exchange, displacement deposition with base metals and electrowinning. The post-leaching solution contains copper as mixture of a form of both of monovalent and divalent, so that oxidation may be preferably conducted, and then all should be divalent copper ions in order to facilitate the solvent extraction and the ion exchange. For a manner for oxidation, without special limitation, a manner that air or oxygen is blown into the post-leaching solution is easy-to-use.
EXAMPLES
[0046]
<Example 1>
A sulfide ores was prepared as a ground product of a copper concentrate containing Cu: 16 mass%, Fe: 26 mass%, S: 28 mass%, and 63 g/t of Au. The leaching test was conducted in which 16 L of a leaching liquid (a first acidic acieuous solution) whose composition is shown in Table 1 was heated to 70 to 85 degrees C, and thereafter 480 g of the copper concentrate was charged, with continuously blowing air (0.2 L/min) and stirring. Metal composition analysis was conducted by ICP atomic emission spectrophotometry method.
<Example 1>
A sulfide ores was prepared as a ground product of a copper concentrate containing Cu: 16 mass%, Fe: 26 mass%, S: 28 mass%, and 63 g/t of Au. The leaching test was conducted in which 16 L of a leaching liquid (a first acidic acieuous solution) whose composition is shown in Table 1 was heated to 70 to 85 degrees C, and thereafter 480 g of the copper concentrate was charged, with continuously blowing air (0.2 L/min) and stirring. Metal composition analysis was conducted by ICP atomic emission spectrophotometry method.
[0047]
[Table 1]
Leaching liquid A Leaching Liquid B
Hydrochloric acid (g/L) 6.9 6.9 Iron(II) chloride (g/L) 2 2 Copper(II) chloride (g/L) 18 18 Total chloride ions (g/L) 180 180 Total bromide ions (g/L) 0 5 Initial ORP 704 720 (vs Ag/AgCI) * With respect to the total chloride ions and total bromide ions, assuming that the contents in the leaching liquid should be completetly ionized, for bromine ion sodium bromide was added to adjust the total ions, and for chlorine ion sodium chloride was added to adjust the total ions to 180 g/L.
[Table 1]
Leaching liquid A Leaching Liquid B
Hydrochloric acid (g/L) 6.9 6.9 Iron(II) chloride (g/L) 2 2 Copper(II) chloride (g/L) 18 18 Total chloride ions (g/L) 180 180 Total bromide ions (g/L) 0 5 Initial ORP 704 720 (vs Ag/AgCI) * With respect to the total chloride ions and total bromide ions, assuming that the contents in the leaching liquid should be completetly ionized, for bromine ion sodium bromide was added to adjust the total ions, and for chlorine ion sodium chloride was added to adjust the total ions to 180 g/L.
[0048]
As resulted in the above Example 1, the relationship between the oxidation-reduction potential ORP at leaching (vs Ag/AgC1) and the leaching rate of either Cu or Au is shown in Table 2 and FIG.
1. The leaching rate was obtained by back calculation from the content of Cu and Au in the leaching residue, based on 100 % of the content of Cu and Au in the sulfide ore. As shown in Table 2 and FIG. 1, for Cu the leaching rate was not different between the leaching liquids A and B; and the ORP was 450 mV and the leaching rate reached to about 90 mass%; and the leaching rate of 99 mass%
or more was obtained at the ORP of 500 mV. On the other hand, for Au, when using the leaching liquid A not containing bromine ions, Au was hardly leached until the ORP reached to 450 mV, and leached to the extent of about 15 mass% at 500 mV. When using the leaching liquid B containing bromine ions, Au was leached to the extent of about 20 mass% at the ORP of 450 mV, and at about 500 mV to the extent of about 40 mass%.
As resulted in the above Example 1, the relationship between the oxidation-reduction potential ORP at leaching (vs Ag/AgC1) and the leaching rate of either Cu or Au is shown in Table 2 and FIG.
1. The leaching rate was obtained by back calculation from the content of Cu and Au in the leaching residue, based on 100 % of the content of Cu and Au in the sulfide ore. As shown in Table 2 and FIG. 1, for Cu the leaching rate was not different between the leaching liquids A and B; and the ORP was 450 mV and the leaching rate reached to about 90 mass%; and the leaching rate of 99 mass%
or more was obtained at the ORP of 500 mV. On the other hand, for Au, when using the leaching liquid A not containing bromine ions, Au was hardly leached until the ORP reached to 450 mV, and leached to the extent of about 15 mass% at 500 mV. When using the leaching liquid B containing bromine ions, Au was leached to the extent of about 20 mass% at the ORP of 450 mV, and at about 500 mV to the extent of about 40 mass%.
[0049]
[Table 2-1]
The leaching liquid A
ORP Cu leaching rate Au leaching rate (mass%) (mass%) 400 54.2 0 437 82.7 0 478 98.8 8.8 544 99. 6 27. 4 546 99. 7 52. 0
[Table 2-1]
The leaching liquid A
ORP Cu leaching rate Au leaching rate (mass%) (mass%) 400 54.2 0 437 82.7 0 478 98.8 8.8 544 99. 6 27. 4 546 99. 7 52. 0
[0050]
[Table 2-2]
The leaching liquid B
ORP Cu leaching rate Au leaching rate (mass%) (mass%) 404 58.5 10.6 443 85.9 17.0 499 99.3 37.8 541 99.6 62.2 543 99.8 83.6
[Table 2-2]
The leaching liquid B
ORP Cu leaching rate Au leaching rate (mass%) (mass%) 404 58.5 10.6 443 85.9 17.0 499 99.3 37.8 541 99.6 62.2 543 99.8 83.6
[0051]
Although the solid-liquid separation was not conducted between the Cu leaching step and the Au leaching step in the above Example 1, based on the results as mentioned above, it may be appreciated that the leaching liquid A not containing bromine ions is employed in the copper leaching step, so that the gold leaching may be inhibited during the copper leaching, whereas the leaching liquid B containing bromine ions is employed in the gold leaching step, so that the gold leaching rate may be raised. For example, it may be appreciated that the leaching liquid A is employed in the copper leaching step with the terminated point at the ORP of 450 to 500 mV, to thereby conduct the solid-liquid separation the resultant, to thereby conduct the gold leaching step while the leaching liquid is switched to the leaching liquid B, so that gold may be recovered at high recovering rate. Further, it may be appreciated that the copper leaching step may be terminated under the condition of the copper leaching rete of 95 mass% or more and the gold leaching rate of 10 mass% or less.
Although the solid-liquid separation was not conducted between the Cu leaching step and the Au leaching step in the above Example 1, based on the results as mentioned above, it may be appreciated that the leaching liquid A not containing bromine ions is employed in the copper leaching step, so that the gold leaching may be inhibited during the copper leaching, whereas the leaching liquid B containing bromine ions is employed in the gold leaching step, so that the gold leaching rate may be raised. For example, it may be appreciated that the leaching liquid A is employed in the copper leaching step with the terminated point at the ORP of 450 to 500 mV, to thereby conduct the solid-liquid separation the resultant, to thereby conduct the gold leaching step while the leaching liquid is switched to the leaching liquid B, so that gold may be recovered at high recovering rate. Further, it may be appreciated that the copper leaching step may be terminated under the condition of the copper leaching rete of 95 mass% or more and the gold leaching rate of 10 mass% or less.
[0052]
<Example 2>
Gold was leached from the post-gold-leaching solution obtained after the gold leaching step by use of a gold leaching liquid containing 50 g/L of chloride ions, 80 g/L of bromide ions, 18 g/L of copper and 0.2 g/L of iron. The post-gold leaching solution contained 84 g/L of NaC1, 103 g/L of NaBr, 20 g/L of Cu, 2 g/L of Fe and 8 mg/L of Au, and had pH of 1.2. Thereto was added CuCl to adjust the ORP of 510 mV. The post-leaching solution was heated to 55 degrees C, and air was blown by 0.4 L a minute with stirring. The resulting post-gold-leaching solution was passed through a glass column filled with about 14 ml of the activated carbon derived from coconut shell (Yashicoal MC, manufactured by Taihei Chemical Industrial Co., Ltd.), to adsorb gold to the activated carbon. The column had the size of 11 mm of diameter and 150 mm of height. The feeding rate of the liquid was 11.9 ml/minute, and the space velocity thereof was 50 (l/h). The eluted gold in the post-adsorption solution was diluted by hydrochloric acid to be determined the quantity thereof by ICP-AES. FIG. 2 shows the relationship between the ORP and the concentration of gold in the post-adsorption solution.
<Example 2>
Gold was leached from the post-gold-leaching solution obtained after the gold leaching step by use of a gold leaching liquid containing 50 g/L of chloride ions, 80 g/L of bromide ions, 18 g/L of copper and 0.2 g/L of iron. The post-gold leaching solution contained 84 g/L of NaC1, 103 g/L of NaBr, 20 g/L of Cu, 2 g/L of Fe and 8 mg/L of Au, and had pH of 1.2. Thereto was added CuCl to adjust the ORP of 510 mV. The post-leaching solution was heated to 55 degrees C, and air was blown by 0.4 L a minute with stirring. The resulting post-gold-leaching solution was passed through a glass column filled with about 14 ml of the activated carbon derived from coconut shell (Yashicoal MC, manufactured by Taihei Chemical Industrial Co., Ltd.), to adsorb gold to the activated carbon. The column had the size of 11 mm of diameter and 150 mm of height. The feeding rate of the liquid was 11.9 ml/minute, and the space velocity thereof was 50 (l/h). The eluted gold in the post-adsorption solution was diluted by hydrochloric acid to be determined the quantity thereof by ICP-AES. FIG. 2 shows the relationship between the ORP and the concentration of gold in the post-adsorption solution.
[0053]
It is recognized that the gold concentration contained in the post-adsorption solution remarkably decreased in case of adjusting the ORP of 520 mV or higher. It is also recognized that although the upper limit of the ORP should not be provided, the gold concentration of the post-adsorption solution should not dramatically decrease when extremely raising the voltage, and that it is enough to oxidize the solution to at least 520 mV, and however it should not be prohibited to extremely oxidize it.
It is recognized that the gold concentration contained in the post-adsorption solution remarkably decreased in case of adjusting the ORP of 520 mV or higher. It is also recognized that although the upper limit of the ORP should not be provided, the gold concentration of the post-adsorption solution should not dramatically decrease when extremely raising the voltage, and that it is enough to oxidize the solution to at least 520 mV, and however it should not be prohibited to extremely oxidize it.
[0054]
<Example 3>
While continuously supplying liquid by used of the column filled with the activated carbon and the post-leaching solution as used in Example 2, the gold concentration of the post-adsorption solution was determined by varying the ORP by the addition of CuCl and blowing air. The result is shown in FIG. 3.
<Example 3>
While continuously supplying liquid by used of the column filled with the activated carbon and the post-leaching solution as used in Example 2, the gold concentration of the post-adsorption solution was determined by varying the ORP by the addition of CuCl and blowing air. The result is shown in FIG. 3.
[0055]
It is also clear based on FIG. 3 that there is a certain relationship between the ORP and the adsorption of gold to the activated carbon. It is possible to favorably recover gold by contacting the post-gold-leaching solution with the activated carbon at the ORP of 520 mV or higher. Further, it is understood that what has an influence on the ORP should be Cu(I).
It is also clear based on FIG. 3 that there is a certain relationship between the ORP and the adsorption of gold to the activated carbon. It is possible to favorably recover gold by contacting the post-gold-leaching solution with the activated carbon at the ORP of 520 mV or higher. Further, it is understood that what has an influence on the ORP should be Cu(I).
[0056]
Although Cu(I) is easily oxidized in an aqueous solution to become Cu(II), in an aqueous solution containing halide at considerably high concentration as in a system of the invention, it may be exist in a considerably stable state. Therefore, although it is estimated to obtain the same effect by oxidizing Cu(I) with an oxidizing agent such as hydrogen peroxide and hypochlorous acid other than by blowing air, blowing air may be preferable from the viewpoint of the cost and the convenience of handling.
Although Cu(I) is easily oxidized in an aqueous solution to become Cu(II), in an aqueous solution containing halide at considerably high concentration as in a system of the invention, it may be exist in a considerably stable state. Therefore, although it is estimated to obtain the same effect by oxidizing Cu(I) with an oxidizing agent such as hydrogen peroxide and hypochlorous acid other than by blowing air, blowing air may be preferable from the viewpoint of the cost and the convenience of handling.
Claims (3)
1. A method of recovering gold from sulfide ores comprising:
Step 1 for contacting a first acidic aqueous solution to sulfide ores with supplying an oxidizing agent to leach a copper content in the sulfide ores, said first acidic aqueous solution containing chlorine ions, copper ions and iron ions with no bromine ions;
Step 2 for subjecting the leaching reaction resultant thus obtained in Step 1 to solid-liquid separation to separate a leaching residue and a post-leaching solution;
Step 3 for contacting a second acidic aqueous solution to said leaching residue thus obtained in Step 2 with supplying an oxidizing agent to leach the gold content in the residue, said second acidic aqueous solution containing chlorine ions, bromine ions, copper ions and iron ions;
Step 4 for adding copper(I) chloride to the post-gold-leaching solution thus obtained in Step 3, and then adding an oxidizing agent to adjust the oxidation-reaction potential (reference electrode: silver/silver chloride) to 520 mV or greater, to thereby reduce monovalent copper ions in the post-gold-leaching solution; and Step 5 for adsorbing gold in the post-gold-leaching solution thus obtained in Step 4 to activated carbon.
Step 1 for contacting a first acidic aqueous solution to sulfide ores with supplying an oxidizing agent to leach a copper content in the sulfide ores, said first acidic aqueous solution containing chlorine ions, copper ions and iron ions with no bromine ions;
Step 2 for subjecting the leaching reaction resultant thus obtained in Step 1 to solid-liquid separation to separate a leaching residue and a post-leaching solution;
Step 3 for contacting a second acidic aqueous solution to said leaching residue thus obtained in Step 2 with supplying an oxidizing agent to leach the gold content in the residue, said second acidic aqueous solution containing chlorine ions, bromine ions, copper ions and iron ions;
Step 4 for adding copper(I) chloride to the post-gold-leaching solution thus obtained in Step 3, and then adding an oxidizing agent to adjust the oxidation-reaction potential (reference electrode: silver/silver chloride) to 520 mV or greater, to thereby reduce monovalent copper ions in the post-gold-leaching solution; and Step 5 for adsorbing gold in the post-gold-leaching solution thus obtained in Step 4 to activated carbon.
2. The method of recovering gold from sulfide ores according to Claim 1, wherein said Step 4 comprises adjusting the oxidation-reaction potential (reference electrode: silver/silver chloride) to 520 mV to 570 mV.
3. The method of recovering gold from sulfide ores according to Claim 1 or 2, wherein said Step 4 comprising the oxidation-reaction potential (reference electrode:
silver/silver chloride) is adjusted by blowing air.
silver/silver chloride) is adjusted by blowing air.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013075226A JP5840642B2 (en) | 2013-03-29 | 2013-03-29 | Method for recovering gold from sulfide minerals |
| JP2013-075226 | 2013-03-29 | ||
| PCT/JP2014/053192 WO2014156349A1 (en) | 2013-03-29 | 2014-02-12 | Method for recovering gold from sulfide ore |
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| Publication Number | Publication Date |
|---|---|
| CA2908688A1 CA2908688A1 (en) | 2014-10-02 |
| CA2908688C true CA2908688C (en) | 2017-09-26 |
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| CA2908688A Active CA2908688C (en) | 2013-03-29 | 2014-02-12 | Method of recovering gold from sulfide ore |
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| Country | Link |
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| JP (1) | JP5840642B2 (en) |
| CA (1) | CA2908688C (en) |
| CL (1) | CL2015002889A1 (en) |
| PE (1) | PE20151715A1 (en) |
| WO (1) | WO2014156349A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6849482B2 (en) * | 2016-03-31 | 2021-03-24 | Ｊｘ金属株式会社 | How to recover gold from ores containing gold or refining intermediates |
| JP6899672B2 (en) * | 2017-03-14 | 2021-07-07 | Ｊｘ金属株式会社 | How to recover gold from ore or refining intermediates |
| CN107287439A (en) * | 2017-06-09 | 2017-10-24 | 张韬 | A kind of environment-friendly type yellow Gold leaching agent and its preparation technology |
| PL3822374T3 (en) * | 2019-11-18 | 2024-01-29 | Heraeus Deutschland GmbH & Co. KG | Method for recovering pure metal |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI118302B (en) * | 2006-02-17 | 2007-09-28 | Outotec Oyj | Procedure for the extraction of gold |
| JP4999108B2 (en) * | 2008-03-27 | 2012-08-15 | Ｊｘ日鉱日石金属株式会社 | Gold leaching method |
| JP4468999B2 (en) * | 2008-03-27 | 2010-05-26 | 日鉱金属株式会社 | Method for recovering metals from minerals |
| JP5319718B2 (en) * | 2011-03-04 | 2013-10-16 | Ｊｘ日鉱日石金属株式会社 | Methods for leaching copper and gold from sulfide ores |
-
2013
- 2013-03-29 JP JP2013075226A patent/JP5840642B2/en active Active
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2014
- 2014-02-12 CA CA2908688A patent/CA2908688C/en active Active
- 2014-02-12 PE PE2015002096A patent/PE20151715A1/en active IP Right Grant
- 2014-02-12 WO PCT/JP2014/053192 patent/WO2014156349A1/en active Application Filing
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Also Published As
| Publication number | Publication date |
|---|---|
| PE20151715A1 (en) | 2015-11-19 |
| WO2014156349A1 (en) | 2014-10-02 |
| CA2908688A1 (en) | 2014-10-02 |
| AU2014245389A1 (en) | 2015-10-08 |
| JP5840642B2 (en) | 2016-01-06 |
| JP2014198887A (en) | 2014-10-23 |
| CL2015002889A1 (en) | 2016-03-28 |
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