Short-process low-cost thiosulfate method continuous and stable gold extraction process

Abstract

The invention discloses a short-process low-cost continuous and stable gold extraction process adopting a thiosulfate method, and belongs to the field of hydrometallurgy. In a closed reactor, by adjusting the concentration of dissolved O2, thiosulfate and a catalyst to be at a low level, the potential of ore pulp is reduced to a suitable range to leach gold ore, and leaching residues and a leaching pregnant solution are obtained through filtering. And pure nitrogen is introduced into the leaching pregnant solution to completely discharge oxygen in the solution, copper powder is added for replacement, and gold-rich crude copper and a replacement barren solution are obtained through filtering. Crude copper rich in gold is treated through electrolytic refining, pure copper is obtained from a cathode, and gold mud is obtained from an anode. And washing the gold mud with dilute acid to obtain a copper-containing pickling solution and pure gold. After the pH of the copper-containing pickling solution is adjusted, the copper-containing pickling solution and the replacement barren solution supplemented with the leaching agent are combined and used for leaching of fresh ore in the next circulation. The method provided by the invention solves the problems of long technological process, high circulation cost and high environmental protection pressure of a copper ammonia catalysis thiosulfate method, and is suitable for being used in a natural environment.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy and relates to a process for continuously and stably extracting gold from a gold mine. Background Art

[0002] Gold is a national strategic metal with extremely low content in the earth's crust. It has excellent physical and chemical properties and is widely used in high-tech industries. Cyanidation is the mainstream technology for extracting gold from gold ore. According to statistics, more than 80% of the world's gold production uses cyanidation. However, cyanide is highly toxic. At the same time, this method has a slow gold leaching rate and a long leaching time. It is not suitable for treating gold mines containing sulfides, copper, etc. that are easy to consume cyanide, and gold mines containing carbon or clay that are easy to "rob gold". Therefore, the gold industry urgently needs the development of non-toxic and non-cyanide gold extraction technology.

[0003] Among the numerous studies on non-cyanide gold extraction technologies, the thiosulfate method is widely considered to be the most potential non-toxic non-cyanide gold extraction method to replace the cyanide method. Without the action of a catalyst, the thiosulfate alone has a slow gold leaching rate and a low gold leaching rate. The introduction of a copper-ammonia catalytic system can significantly improve the gold leaching capacity of thiosulfate. Methods for recovering gold from copper-ammonia catalyzed thiosulfate gold leaching precious solution include metal replacement, activated carbon adsorption, solvent extraction, electrodeposition, and lipid adsorption. The metal replacement process is simple and mature, but the crude gold product obtained by replacement has a low gold grade. At the same time, no systematic solution circulation research has been conducted, and the stability of various gold recovery indicators is unclear. Activated carbon adsorption method Activated carbon for Au(S2O3)2 3– The adsorption capacity of the complex ion is weak, and the gold recovery rate is low. The solvent extraction method has high requirements for solution clarity and gold concentration in the leached precious solution. The extractant is expensive and the extractant is an organic reagent that is prone to secondary pollution. The electrodeposition method has high requirements for solution clarity, low current efficiency, and difficult solution circulation. The resin adsorption method is widely considered to be the most suitable for recovering gold from thiosulfate leached precious solution. It has low requirements for solution clarity, and the resin has the advantages of large adsorption capacity and reusability, but Cu(S2O3)3 5– Au(S2O3)2 3– The competitive adsorption results in the need for a complex two-stage desorption process for gold recovery.

[0004] As an existing technology, the method of using copper-ammonia catalyzed thiosulfate leaching and using resin adsorption to recover gold in the gold leaching solution has inherent "three major problems", namely: first, Cu(NH3)4 2+ / O2 vs S2O3 2– Strong oxidation effect, S2O3 2– The large amount of thiosulfate reagents consumed leads to a large amount of thiosulfate reagents consumed. Second, ammonia water is volatile and has a certain degree of toxicity, and ammonia threatens the environment. Third, Cu(S2O3)3 5– Au(S2O3)2 adsorbed on resin3– Competition leads to complicated gold recovery process. To this end, researchers have carried out a lot of related research work. It mainly includes the following two aspects. On the one hand, in the process of copper-ammonia thiosulfate gold leaching, the control measures of adjusting the gold leaching reaction conditions or using additives are adopted to reduce the consumption of thiosulfate. However, in the process of gold leaching, the reaction conditions are constantly changing, and it is difficult to accurately control them. At the same time, there are great limitations in the selection of additives, and there is no additive that can be generally applied to a variety of gold mines. On the other hand, new catalytic systems that replace the copper-ammonia catalytic system are studied, such as copper-citric acid / ethylenediamine, iron-oxalic acid / EDTA / sulfosalicylic acid, nickel / cobalt-ammonia, nickel / cobalt-glycine, etc., but these catalytic systems either replace copper alone but still have the problem of ammonia threatening the environment, or replace ammonia alone but still have the problem of complex gold recovery process, or both copper and ammonia are replaced but the reagents are expensive or toxic. Therefore, the thiosulfate gold extraction technology has not been promoted and applied in industry.

[0005] The Chinese invention patent application with publication number CN117947278A discloses a "thiosulfate method for gold extraction". The method first uses a copper-containing catalyst system-thiosulfate solution to leach gold-containing materials to obtain a thiosulfate leachate containing precious metals; then, a sulfur-containing thiosulfate solution is added to the thiosulfate leachate containing precious metals. 2- The invention claims to solve the problems of large consumption of thiosulfate and difficulty in gold recovery, and simplifies the gold leaching process. Although the process disclosed in the patent is simple, it uses S-containing 2- The reducing agent is used to precipitate gold and copper in the thiosulfate leaching precious solution, but there are two serious problems: (1) Containing S 2- The reducing agent is expensive first, and the amount of precipitation added is difficult to control. If too little is added, the gold will not be precipitated cleanly, and if too much is added, the leaching solution will contain too many sulfur ions, causing copper ions to precipitate again when catalyst copper ions are added during the next leaching. Excessive addition of catalyst copper ions will increase the cost of gold leaching.

[0006] (2) Add S 2- During the replacement, the catalyst copper ions will be precipitated to form CuS or CuS2. His invention mentioned the use of dilute acid to leaching copper, but CuS or CuS2 is insoluble in dilute acid, and it is difficult to separate the gold and copper after subsequent precipitation. At the same time, the copper-containing leaching solution mentioned in his process has very little copper content. Even if the leaching solution is returned for leaching, a large amount of catalyst copper still needs to be added during leaching, which greatly increases the leaching cost.

[0007] In summary, during leaching, the leaching cost is still very high, the actual operation of this process is difficult, and recovery difficulties are still a problem. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a short-process, low-cost, continuous and stable gold extraction process using a thiosulfate method, which overcomes the above-mentioned defects of the prior art, further reduces the gold extraction cost, shortens the gold extraction process, and improves the stability of various gold extraction indicators.

[0009] The technical solution of the present invention is as follows: A short-process, low-cost, continuous and stable gold extraction process using thiosulfate, comprising the following steps: (1) In a closed reactor, the slurry potential is lowered to an appropriate range by adjusting the dissolved O2, thiosulfate concentration and copper ammonia catalyst concentration within a certain range of lower levels to leach the gold ore, and the leaching residue and leaching precious liquid are obtained by filtering; (2) introducing pure nitrogen into the leaching precious solution to exhaust oxygen from the solution, then adding copper powder for replacement, and filtering to obtain gold-rich crude copper and replacement lean solution; (3) Electrolytic refining is used to treat gold-rich crude copper, where pure copper is obtained at the cathode and gold mud is obtained at the anode; (4) The gold mud is washed with dilute acid to obtain a copper-containing pickling solution and pure gold; The said adjusting the dissolved O2 concentration at a lower level refers to controlling the average dissolved O2 concentration between 0.25 and 0.35 mg / L; the said adjusting the leaching agent thiosulfate at a lower level refers to adjusting the thiosulfate concentration at 0.05 to 0.08 mol / L; the said adjusting the copper ammonia catalyst concentration at a lower level refers to adjusting the copper sulfate concentration to 0.5 to 1 mmol / L and the ammonia water concentration to 0.4 to 0.8 mol / L; the said lowering the slurry potential to an appropriate range refers to controlling the slurry potential at 195 to 205 mV.

[0010] Preferably, the thiosulfate refers to one or more of calcium thiosulfate, sodium thiosulfate and ammonium thiosulfate.

[0011] Preferably, the conditions for leaching the gold ore in step (1) are as follows: the slurry concentration is 25-50%, the portion of the gold ore ground to a particle size of -200 mesh accounts for more than 90wt% of the total proportion, and during leaching, the reaction temperature is controlled to be 25-35°C, the pH value of the reaction system is 9-12, the reaction time is 8-12 h, and the stirring speed is 200-400 r / min.

[0012] Preferably, the amount of copper powder used in step (2) is 300 times the theoretical amount.

[0013] Preferably, the electrolytic refining conditions in step (3) are: the electrolyte is one of sulfuric acid or nitric acid, the electrolysis temperature is 25-35°C, and the current density is 100-230 A / m 2 , electrolysis time 12~48 h.

[0014] Preferably, the pure copper refers to pure copper of 3N copper or above; the pure gold refers to pure gold of 3N gold or above; and the gold mud obtained by electrolytic refining of the anode refers to gold mud with a gold content of more than 97%.

[0015] Preferably, the acid used for the dilute acid washing in step (4) is one or both of sulfuric acid and nitric acid; the pickling conditions are: acid concentration of 0.5-2 mol / L, acid addition at a solid-liquid ratio of 1:(2-3), pickling time of 1-2 h, pickling temperature of 25-100°C, and stirring speed of 200-400 r / min.

[0016] Preferably, in step (2), the pure nitrogen gas flow rate is 1-3 ml / min; and the copper powder used has a fineness of -200-+400 mesh.

[0017] Preferably, thiosulfate is added to the replacement barren solution obtained in step (2), and the pH of the copper-containing pickling solution obtained in step (4) is adjusted to 10, and then the replacement barren solution supplemented with thiosulfate and the copper-containing pickling solution with adjusted pH are combined for leaching of fresh ore in the next cycle.

[0018] Further preferably, the thiosulfate added to the replacement barren solution includes one or more of calcium thiosulfate, sodium thiosulfate, and ammonium thiosulfate; the amount of thiosulfate added is to add the thiosulfate concentration in the leachate to 0.05-0.08 mol / L. During the leaching process, the lower the dissolved oxygen concentration, the weaker its oxidizing effect on the leaching agent thiosulfate, and the lower the consumption of thiosulfate. However, the dissolved O2 cannot be too low, otherwise it will affect the leaching rate and gold leaching rate. Therefore, the present invention controls the average concentration of dissolved O2 between 0.25 and 0.35 mg / L.

[0019] During the leaching process, the thiosulfate concentration increases, the gold leaching rate is fast, but the oxidation and decomposition products of the leaching agent increase, and the consumption increases; when the concentration decreases, the gold leaching rate can be increased by appropriately extending the leaching time, and the oxidation and decomposition products of the leaching agent decrease, and the consumption decreases. Therefore, the present invention adjusts the thiosulfate concentration to 0.05-0.08 mol / L.

[0020] If the slurry potential is too high, the catalytic oxidation decomposition of thiosulfate will be enhanced, and the consumption of thiosulfate will increase; if the slurry potential is too low, the gold leaching rate will be slow and the gold leaching rate will be low. Therefore, the present invention controls the slurry potential to be 195-205mV.

[0021] Properly increasing the ammonia concentration can form Cu(NH3)4 2+ Stabilize copper ions and reduce Cu 2+ The invention can reduce the oxidation of the leaching agent thiosulfate. In addition, the reduction of the reagent concentration is conducive to reducing the reagent cost. Therefore, the present invention adjusts the copper sulfate concentration to 0.5-1 mmol / L and the ammonia concentration to 0.4-0.8 mol / L.

[0022] In the reaction process of the present invention, oxygen is not added to the closed reactor, and only the air in the reactor and the dissolved oxygen in the slurry at the beginning can meet the oxygen required for the gold leaching process. The consumption of the thiosulfate leaching agent is reduced by controlling the low dissolved oxygen concentration of the slurry.

[0023] The amount of copper powder needs to be excessive, otherwise the replacement is not sufficient. The possible reasons are: on the one hand, in addition to gold, there are other metal ions in the solution that can be replaced by copper powder; on the other hand, the metal replaced by copper powder in the solution covers the surface of copper powder, forming a passivation film, which hinders the replacement of copper powder. Therefore, the amount used in the present invention is 300 times the theoretical amount (copper and gold are replaced at a ratio of 1:2). The amount of copper powder is greatly increased to ensure that gold is completely replaced.

[0024] If the amount of acid used is too little, the copper leaching rate in the gold mud is low and the copper leaching is incomplete; if the amount of acid used is too much, the cost of the acid is too high, and a large amount of alkali needs to be added to adjust the pH value before it can be combined with the second-stage leaching precious liquid for return and use, and the alkali consumption is large. Therefore, the present invention controls the acid concentration to 0.5~2 mol / L.

[0025] Compared with the prior art, the advantages of the present invention are: 1. The thiosulfate gold extraction process of the present invention significantly reduces the cost of gold extraction. First, when copper-ammonia catalyzes thiosulfate gold leaching, copper-ammonia catalyzes thiosulfate gold leaching in an open reactor. During the stirring process of gold leaching, ammonia is very volatile, and the concentration of the gold leaching reagent needs to be increased to ensure the leaching kinetics of gold. First, the amount of thiosulfate leaching agent is large. Second, Cu(NH3)4 2+ For S2O3 2– In addition, the dissolved oxygen content in the solution in the open reactor is high, and O2 has a strong effect on S2O3 2– The oxidation effect is strong. This leads to a large consumption of thiosulfate as a leaching agent. The present invention adjusts the concentration of dissolved O2, leaching agent (thiosulfate) and catalyst (copper, ammonia) at a lower level, so that the slurry potential drops to an appropriate range, and gold is leached in a closed reactor, avoiding the threat of ammonia volatilization to the environment, significantly reducing the amount of leaching agent and Cu(NH3)4 2+ / O2 vs S2O3 2–The strong oxidizing effect of copper powder significantly reduces the consumption of gold leaching reagents (especially thiosulfate). Second, when copper powder is used to replace and recover gold, the amount of copper powder used is 300 times the theoretical amount. The amount of copper powder used is low, the consumption is small, and the gold recovery cost is significantly reduced. Third, the present invention combines the replacement lean solution supplemented with the leaching agent thiosulfate and the copper-containing pickling solution (pH adjusted to 10). The combined solution can be directly used for the leaching of fresh ore in the next cycle without adding copper sulfate. That is, the copper consumed in the copper powder replacement in the previous cycle can be used to supplement the copper required for the current cycle of gold leaching, which significantly reduces the cost of catalytic gold leaching of gold ore. In summary, the process of the present invention can significantly reduce the gold extraction cost of the entire solution cycle.

[0026] 2. The thiosulfate gold extraction process of the present invention can significantly shorten the gold extraction process. According to the gold extraction process of the present invention, finely ground gold ore only needs to go through leaching, copper powder replacement, electrolytic refining, pickling and impurity removal, and ingot casting to obtain gold ingots. Compared with other thiosulfate gold leaching and recovery processes proposed in the industry, the gold extraction process is greatly shortened, and the process investment and production costs are reduced.

[0027] 3. The thiosulfate gold extraction process of the present invention has stable gold extraction indicators by solution circulation. When thiosulfate is used to leach actual gold ore, metal elements such as Cu, Ag, Hg, etc. in the gold ore will inevitably dissolve into the leachate. As the number of solution cycles increases, the accumulation of these inevitable metal ions will affect the leaching of gold to varying degrees and affect the stability of gold recovery indicators. The process of the present invention uses copper powder replacement, which, in addition to replacing the target metal, can also remove most of the inevitable metal ions in the leachate, thereby achieving the purification of the leachate, which is more conducive to the continuous and stable use of the leachate, and further improves the stability of various gold extraction indicators.

[0028] Fourth, the present invention introduces nitrogen into the leaching solution to exhaust oxygen, which is beneficial to reducing the amount of copper powder used and the amount of dissolution, while preventing gold from re-dissolving after being replaced, further improving the metal replacement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a process flow chart of the thiosulfate method for gold extraction. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0031] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] The following are comparative examples and examples of gold extraction from quartz vein-type oxidized gold ore.

[0034] Raw material 1: The raw material is a quartz vein type oxidized gold ore with a gold grade of 2.66 g / t and a main gangue component of SiO2 with a content of 88.6%. The ore is first crushed and wet ball milled to -200 mesh accounting for 90% by weight, and the slurry is adjusted to a mass concentration of 33% to obtain raw material slurry 1. It should be noted that the "t -矿 ” represents the quality of the ore.

[0035] Comparative Example 1

[0036] Copper sulfate, ammonia water, and sodium thiosulfate were added to the raw material slurry to 0.02 mol / L, 1.5 mol / L, and 0.20 mol / L, respectively. Then, the pH value of the slurry was adjusted to 10.0 with sodium hydroxide and sulfuric acid. The leaching was carried out for 8.0 h at a stirring speed of 300 r / min at 25°C in an open reactor. During the leaching process, the slurry potential was maintained at 241-253 mV, and the dissolved oxygen concentration was 0.65-0.71 mg / L. The leaching rate of gold was 86.53%, and the consumption of copper sulfate, ammonia water, and sodium thiosulfate was 1.01 kg / t, respectively. -矿 、32 kg / t -矿 , 27.8 kg / t -矿 . Example 1

[0037] like Figure 1 As shown, this embodiment includes the following steps: (1) Taking the raw material slurry 1 as the object, copper sulfate, ammonia water and sodium thiosulfate with low reagent concentration were used for leaching. The leaching conditions were: copper sulfate 0.001 mol / L (copper ion concentration 63.5 mg / L), ammonia water 0.8 mol / L, sodium thiosulfate 0.07 mol / L, stirring speed 400 r / min, and the slurry pH was adjusted to 10. Leaching was carried out in a closed reactor at 25°C for 8.0 h. During the leaching process, the slurry potential was maintained at 196~200 mV, and the average dissolved oxygen concentration was controlled at about 0.3 mg / L. The leaching rate of gold was 86.84%, and the consumption of copper sulfate and sodium thiosulfate was 0.22 kg / t, respectively. -矿 , 12.42 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0038] (2) Nitrogen is passed through the leached precious liquid obtained after gold leaching and filtration in step (1) to exhaust the air, and then copper powder is added to carry out metal replacement reaction to obtain gold-rich crude copper and replacement lean liquid. The replacement is carried out at a mass ratio of gold to copper of 2:1, and the amount of copper powder used is 300 times the theoretical amount (copper and gold are replaced at a ratio of 1:2). Under the above conditions, the gold replacement rate is 99.48%, and the copper powder consumption is 0.042kg / t -矿 .

[0039] (3) The gold-rich crude copper obtained in step (2) is subjected to electrolytic refining. The electrolytic refining conditions are: the electrolyte is sulfuric acid, the electrolysis temperature is 25°C, and the current density is 220 A / m 2 , electrolysis time 48 h, to obtain gold mud with a gold content of 98.34% and pure copper (cathode copper) with a copper content of 99.96%.

[0040] (4) The gold mud obtained in step (3) was stirred and washed with 1 mol / L dilute sulfuric acid at a stirring speed of 300 r / min, a time of 1 h, a temperature of 80°C, and a solid-liquid ratio of 1:2. After washing, a copper-containing acid washing solution with 99.91% pure gold and a copper content of 20.3 mg / L was obtained. Example 2

[0041] This embodiment further includes the following steps: First, a sample is taken from the replacement barren solution obtained in step (2) of Example 1, and the sodium thiosulfate concentration is obtained by titration to be 0.052 mol / L. Secondly, the copper-containing pickling solution obtained in step (4) of Example 1 is adjusted to pH 10. Finally, the replacement barren solution and the copper-containing pickling solution with adjusted pH are combined for leaching of fresh ore in the next cycle. By titration and ICP analysis, the concentrations of copper ions and ammonia water in the leachate at the beginning of leaching are 63.68 mg / L and 0.78 mol / L, respectively. During the leaching process, the pulp potential is maintained at 197-202 mV, the average dissolved oxygen concentration is controlled at about 0.27 mg / L, the leaching time is 12 h, the leaching temperature is 35°C, and the other leaching conditions are consistent with step (1) in Example 1. After leaching, the gold leaching rate is 85.92%, and the consumption of copper sulfate and sodium thiosulfate is 0.092 kg / t, respectively. -矿 , 10.26 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0042] The operations of steps (2) and (3) of this embodiment are the same as those of steps (2) and (3) of embodiment 1. According to the above conditions, the gold replacement rate in step (2) is 98.88%, and the copper powder consumption is 0.034 kg / / t -矿 In step (3), gold mud with a gold content of 97.99% and pure copper (cathode copper) with a copper content of 99.85% are obtained.

[0043] The difference between step (4) of this embodiment and step (4) of embodiment 1 is that the gold mud obtained in step (3) is stirred and washed with 2 mol / L dilute sulfuric acid for 1.5 h, with a solid-liquid ratio of 1:3 and a stirring speed of 200 r / min. After washing according to this embodiment, a copper-containing acid washing solution with 99.97% pure gold and a copper content of 24.66 mg / L is obtained. Example 3

[0044] This embodiment further includes the following steps: adding calcium thiosulfate to 0.08 mol / L of the replacement barren solution obtained in step (2) of Example 1, and adjusting the pH of the copper-containing pickling solution obtained in step (4) of Example 1 to 10, and then combining the replacement barren solution supplemented with calcium thiosulfate and the copper-containing pickling solution with adjusted pH for leaching of fresh ore in the next cycle. According to titration and ICP analysis, the concentrations of copper ions and ammonia water in the leachate at the beginning of leaching were 62.14 mg / L and 0.76 mol / L, respectively. During the leaching process, the pulp potential was maintained at 195-199 mV, the average dissolved oxygen concentration was controlled at about 0.34 mg / L, the temperature was 35°C, the leaching time was 10 h, and the other leaching conditions were consistent with step (1) in Example 1. After leaching, the gold leaching rate was 87.11%, and the consumption of copper sulfate and calcium thiosulfate was 0.079 kg / t, respectively. -矿 , 10.1 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0045] The operation of step (2) of this embodiment is the same as step (2) of embodiment 1. According to the above conditions, the gold replacement rate in step (2) is 99.37%, and the copper powder consumption is 0.053 kg / t -矿 .

[0046] The difference between step (3) of this embodiment and step (3) of embodiment 1 is that the current density is 100 A / m 2 , electrolysis time 24 h, electrolysis temperature 35 ° C. According to the above conditions, gold mud with a gold content of 98.26% and pure copper with a copper content of 99.93% were obtained.

[0047] The difference between step (4) of this embodiment and step (4) of embodiment 1 is that the gold mud is stirred and washed with 0.5 mol / L dilute sulfuric acid, the washing stirring time is 2 h, the temperature is 70°C, the solid-liquid ratio is 1:3, and the stirring speed is 400 r / min. After washing according to this embodiment, a copper-containing acid washing solution with 99.9% pure gold and a copper content of 18.91 mg / L is obtained. The following are comparative examples and examples of gold extraction from sulfide gold ores.

[0048] Raw material 2: The raw material is a sulfide gold mine with a gold grade of 48 g / t. The main gangue components are pyrite, SiO2 and mica, and also contain a small amount of chalcopyrite. The gold in the gold mine is less encapsulated and belongs to an easily leached gold mine. First, the ore is crushed and wet-ball milled to -200 mesh, accounting for 90% by weight, and the slurry is adjusted to a mass concentration of 25% to obtain raw material slurry 2.

[0049] Comparative Example 2

[0050] Copper sulfate, ammonia water, and ammonium thiosulfate were added to the raw material slurry 2 in sequence to 0.03 mol / L, 1.5 mol / L, and 0.30 mol / L, respectively. Then, the pH value of the slurry was adjusted to 10.0 with sodium hydroxide and sulfuric acid. The leaching was carried out for 8.0 h at 30°C in an open reactor at a stirring speed of 300 r / min. During the leaching process, the slurry potential was maintained at 247~258 mV, and the dissolved oxygen concentration was 0.7~0.74 mg / L. The leaching rate of gold was 83.65%, and the consumption of copper sulfate, ammonia water, and ammonium thiosulfate was 1.24 kg / t, respectively. -矿 、36.41 kg / t -矿 、34.59 kg / t -矿 . Example 4

[0051] (1) Taking the raw material slurry 2 as the object, copper sulfate, ammonia water and ammonium thiosulfate with low reagent concentration were used for leaching. The leaching conditions were: copper sulfate 0.0005 mol / L (copper ion concentration 31.5 mg / L), ammonia water 0.45 mol / L, ammonium thiosulfate 0.075 mol / L, stirring speed 400 r / min, pH=10. Leaching was carried out in a closed reactor at 30°C for 12.0 h. During the leaching process, the slurry potential was maintained at 197~201 mV, and the average dissolved oxygen concentration was controlled at about 0.28 mg / L. The leaching rate of gold was 83.14%, and the consumption of copper sulfate and ammonium thiosulfate was 0.35 kg / t respectively. -矿 , 17.61 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0052] (2) Nitrogen is passed through the leached precious solution obtained after gold leaching and filtration in step (1) to exhaust the air, and then copper powder is added to carry out metal replacement reaction to obtain gold-rich crude copper and replacement lean solution. The replacement is carried out at a mass ratio of gold to copper of 2:1, and the amount of copper powder used is 300 times the theoretical amount (copper and gold are replaced at a ratio of 1:2). Under the above conditions, the gold replacement rate is 98.66%, and the copper powder consumption is 0.064kg / t -矿 .

[0053] (3) The gold-rich crude copper obtained in step (2) is subjected to electrolytic refining. The electrolytic refining conditions are: the electrolyte is sulfuric acid, the electrolysis temperature is 30°C, and the current density is 220 A / m 2 , electrolysis time 24 h, to obtain gold mud with a gold content of 97.89% and pure copper (cathode copper) with a copper content of 99.91%.

[0054] (4) The gold mud obtained in step (3) was stirred and washed with 1 mol / L dilute sulfuric acid at a stirring speed of 300 r / min, a time of 1 h, a temperature of 80°C, and a solid-liquid ratio of 1:2. After washing, a copper-containing acid washing solution with 99.95% pure gold and a copper content of 21.81 mg / L was obtained. Example 5

[0055] This embodiment further includes the following steps: sodium thiosulfate is added to the replacement barren solution obtained in step (2) of Example 4 to 0.06 mol / L, and the copper-containing pickling solution obtained in step (4) of Example 4 is adjusted to pH 10, and then the replacement barren solution supplemented with sodium thiosulfate is combined with the copper-containing pickling solution with adjusted pH for leaching of fresh ore in the next cycle. According to titration and ICP analysis, the concentrations of copper ions and ammonia water in the leachate at the beginning of leaching are 29.97 mg / L and 0.43 mol / L, respectively. During the leaching process, the pulp potential is maintained at 199-203 mV, the average dissolved oxygen concentration is controlled at about 0.31 mg / L, the temperature is 35°C, the leaching time is 11 h, and the other leaching conditions are consistent with step (1) in Example 4. After leaching, the gold leaching rate is 82.92%, and the consumption of copper sulfate and sodium thiosulfate is 0.094 kg / t, respectively. -矿 、17.28 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0056] The operation of step (2) of this embodiment is the same as step (2) of embodiment 4. According to the above conditions, the gold replacement rate in step (2) is 99.06%, and the copper powder consumption is 0.06 kg / t -矿 .

[0057] The difference between step (3) of this embodiment and step (3) of embodiment 4 is that the current density is 150 A / m 2 , electrolysis time 48 h. Gold mud with a gold content of 98.3% and pure copper with a copper content of 99.92% were obtained.

[0058] The difference between step (4) of this embodiment and step (4) of embodiment 4 is that the gold mud is stirred and washed with 0.5 mol / L dilute sulfuric acid at a temperature of 90°C, a solid-liquid ratio of 1:3, and a washing time of 2 h. After washing, a copper-containing acid washing solution with 99.93% pure gold and a copper content of 25.1 mg / L is obtained. Example 6

[0059] This embodiment further includes the following steps: sodium thiosulfate is added to the replacement barren solution obtained in step (2) of Example 5 to 0.08 mol / L, and the copper-containing pickling solution obtained in step (4) of Example 5 is adjusted to pH 10, and then the replacement barren solution supplemented with sodium thiosulfate is combined with the copper-containing pickling solution with adjusted pH for leaching of fresh ore in the next cycle. According to titration and ICP analysis, the concentrations of copper ions and ammonia water in the leachate at the beginning of leaching are 29.1 mg / L and 0.41 mol / L, respectively. During the leaching process, the pulp potential is maintained at 198-202 mV, the average dissolved oxygen concentration is controlled at about 0.27 mg / L, the temperature is 25°C, the leaching time is 9 h, and the other leaching conditions are consistent with step (1) in Example 4. After leaching, the gold leaching rate is 83.11%, and the consumption of copper sulfate and sodium thiosulfate is 0.11 kg / t, respectively. -矿 、18.15 kg / t -矿 , since the leaching occurs in a closed reactor, the consumption of aqueous ammonia can be ignored.

[0060] The operation of step (2) of this embodiment is the same as step (2) of embodiment 4. According to the above conditions, the gold replacement rate in step (2) is 98.46%, and the copper powder consumption is 0.074 kg / t -矿 .

[0061] The difference between step (3) of this embodiment and step (3) of embodiment 4 is that the electrolysis temperature is 25°C and the current density is 200 A / m 2 , and obtain gold mud with a gold content of 98.4% and pure copper with a copper content of 99.86%.

[0062] The difference between step (4) of this embodiment and step (4) of embodiment 4 is that the gold mud is stirred and washed with 2 mol / L dilute sulfuric acid, the washing stirring time is 1.5 h, the temperature is 90°C, the solid-liquid ratio is 1:3, and the stirring speed is 200 r / min. After washing, 99.93% pure gold and a copper-containing acid washing solution with a copper content of 22.61 mg / L are obtained.

[0063] The pure gold obtained in the above embodiments is melted and cast to obtain gold ingots.

[0064] The closed reactor of the present invention mainly refers to a completely closed glass reactor. During the reaction process, the pH and dissolved oxygen concentration of the leaching solution in the closed reactor can be detected.

[0065] The nitrogen-purging air uses pure nitrogen at a flow rate of 1-3 ml / min.

[0066] The copper powder used for metal replacement refers to copper powder with a fineness of -200~+400 mesh.

[0067] The copper concentration in the replacement lean solution increases by 20-25 mg / L due to the dissolution of copper powder.

[0068] The gold-rich crude copper refers to crude copper having a gold content of 13.04-13.95 kg / t and a copper content of 98.5-98.6% after copper powder replacement.

Claims

1. A short-process, low-cost, continuous and stable gold extraction process using thiosulfate, characterized in that The following steps are involved: (1) In a closed reactor, the slurry potential is lowered to an appropriate range by adjusting the dissolved O2, the concentration of the leaching agent thiosulfate and the concentration of the copper ammonia catalyst within a certain range of a lower level to leach the gold ore, and the leaching residue and the leaching precious liquid are obtained by filtering; (2) introducing pure nitrogen into the leaching precious solution to exhaust oxygen from the solution, then adding copper powder for replacement, and filtering to obtain gold-rich crude copper and replacement lean solution; (3) Electrolytic refining is used to treat gold-rich crude copper, where pure copper is obtained at the cathode and gold mud is obtained at the anode; (4) The gold mud is washed with dilute acid to obtain a copper-containing pickling solution and pure gold; The said adjusting the dissolved O2 concentration at a lower level refers to controlling the average dissolved O2 concentration between 0.25 and 0.35 mg / L; the said adjusting the leaching agent thiosulfate at a lower level refers to adjusting the thiosulfate concentration at 0.05 to 0.08 mol / L; the said adjusting the copper ammonia catalyst concentration at a lower level refers to adjusting the copper sulfate concentration to 0.5 to 1 mmol / L and the ammonia water concentration to 0.4 to 0.8 mol / L; the said lowering the slurry potential to an appropriate range refers to controlling the slurry potential at 195 to 205 mV.

2. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate according to claim 1 is characterized in that: The thiosulfate refers to one or more of calcium thiosulfate, sodium thiosulfate and ammonium thiosulfate.

3. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate as claimed in claim 1 is characterized by: The conditions for leaching the gold ore in step (1) are as follows: the slurry concentration is 25-50%, the gold ore ground to a particle size of -200 mesh accounts for more than 90wt% of the total proportion, during leaching, the reaction temperature is controlled to be 25-35°C, the pH value of the reaction system is 9-12, the reaction time is 8-12 h, and the stirring speed is 200-400 r / min.

4. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate method according to claim 1 is characterized in that: The amount of copper powder used in step (2) is 300 times the theoretical amount.

5. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate as claimed in claim 1 is characterized by: The electrolytic refining conditions in step (3) are as follows: the electrolyte is one of sulfuric acid or nitric acid, the electrolysis temperature is 25-35°C, and the current density is 100-230 A / m 2 , electrolysis time 12~48 h.

6. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate as claimed in claim 1 is characterized by: The pure copper refers to pure copper above 3N copper; the pure gold refers to pure gold above 3N gold; the gold mud obtained by electrolytic refining of anodes refers to gold mud with a gold content of more than 97%.

7. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate method according to claim 1 is characterized by: The acid used for the dilute acid washing in step (4) is one or both of sulfuric acid and nitric acid; the pickling conditions are: acid concentration of 0.5~2 mol / L, acid amount added at a solid-liquid ratio of 1:(2~3), pickling time of 1~2 h, pickling temperature of 25~100°C, and stirring speed of 200~400 r / min.

8. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate as claimed in claim 1 is characterized by: In step (2), the pure nitrogen gas flow rate is 1-3 ml / min; the copper powder used has a fineness of -200-+400 mesh.

9. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate according to any one of claims 1 to 8, characterized in that: Thiosulfate is added to the replacement barren solution obtained in step (2), and the pH of the copper-containing pickling solution obtained in step (4) is adjusted to 10. The replacement barren solution supplemented with thiosulfate and the copper-containing pickling solution with adjusted pH are then combined for leaching of fresh ore in the next cycle.

10. The short-process, low-cost, continuous and stable gold extraction process using thiosulfate as claimed in claim 9, characterized in that: The thiosulfate added to the replacement barren solution includes one or more of calcium thiosulfate, sodium thiosulfate, and ammonium thiosulfate; the amount of thiosulfate added is to increase the thiosulfate concentration in the leachate to 0.05-0.08 mol / L.

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