Precious metal leaching agent based on thiosulfate and precious metal leaching process

Abstract

The invention discloses a precious metal leaching agent based on thiosulfate and a precious metal leaching process. The leaching agent contains thiosulfate, a thiourea-based catalyst and an iron-based oxidizing agent, and the molar ratio of the thiosulfate to the thiourea-based catalyst to the iron-based oxidizing agent is (0.05-5): (0.005-1): (0.005-1). According to the leaching agent, on the basis of the synergistic effect of all the components, the dissolution efficiency of precious metal is improved, generation of polysulfate in side reaction is greatly reduced, and follow-up precious metal recovery is facilitated. A leaching process adopting the leaching agent comprises the following steps: exposing precious metal sites of a precious metal-containing material, adding the leaching agent, adjusting the pH value of a leaching system, carrying out a leaching reaction, and carrying out solid-liquid separation after the reaction is finished, so as to obtain a precious metal leachate. According to the technology, by controlling the pH value of the system and the adding amount of the leaching agent, leaching of different grades and types of precious metal-containing materials can be achieved under the normal temperature condition, and tests show that by taking gold ore as an example, the gold recovery rate of the technology can reach 100% at most.

Description

Technical Field

[0001] The present invention relates to a wet leaching process for precious metals, in particular to a thiosulfate-based precious metal leaching agent and a precious metal leaching process, belonging to the technical field of precious metal leaching and recovery. Background Art

[0002] Alkaline cyanidation has been used to extract gold from ore for over 100 years and remains the primary method for gold production worldwide. However, the unavoidable use of highly toxic cyanide during the cyanidation process poses significant risks to human health and environmental safety. Furthermore, with some regions prohibiting the construction of new cyanide plants, the difficulty and cost of obtaining cyanide have increased. Against this backdrop, research has focused on developing non-toxic leaching agents for gold, including thiosulfate leaching agents.

[0003] The oxidation reaction of thiosulfate and gold can dissolve gold in the solution. The general reaction process is as follows:

[0004] 4Au+8S2O3 2- +O2+2H2O→4Au(S2O3)2 3- +4OH - ;

[0005] Although the reaction is thermodynamically feasible, kinetically, gold dissolution is very slow unless a catalyst and a redox mediator are present. This is believed to be due to the following reasons: 1) oxygen is not an effective oxidant for gold, resulting in a slow reduction rate on the gold surface; and 2) gold is extremely chemically stable, and during the initial dissolution process, thiosulfate tends to form a passivation layer on the gold surface, hindering further dissolution.

[0006] In order to solve the above problems, the prior art proposes an ammonia-copper thiosulfate leaching agent. The tetraammine copper (II) complex in the leaching agent reacts quickly with precious metals such as gold and silver, and is an effective oxidant for the precious metals. It can also be regenerated by oxidizing the copper (I) complex, while ammonium thiosulfate can effectively stabilize copper. In addition, the prior art shows that both ammonia and copper have a catalytic effect on the anodic reaction of precious metal oxidation. Therefore, the leaching agent can provide an effective oxidant and catalyst for the precious metal leaching reaction, thereby increasing the leaching rate of the precious metals.

[0007] However, the aforementioned leaching agents still present the following challenges: 1) The introduction of large amounts of ammonia poses significant risks to human health and environmental safety, which is inconsistent with the concept of green environmental protection technology; 2) The leaching agent primarily uses copper to induce the catalytic oxidation of thiosulfate, resulting in high reagent consumption throughout the leaching process; 3) Side reaction products during the leaching process, along with polydisulfate, are detrimental to the downstream precious metal recovery process, making it difficult to precipitate and recover the precious metals, significantly reducing the overall precious metal yield. Furthermore, some institutions have attempted to bond gold and silver precious metals in thiosulfate-based solutions, but all attempts have been unsuccessful. It is well known that base metal substrates can become passivated during precious metal recovery, resulting in low bonding and low precious metal recovery rates. Furthermore, in the recovery of some precious metals, such as silver, pre-reduction of the oxidant is still insufficient to achieve acceptable bonding levels.

[0008] Therefore, even if the leaching agent in the prior art effectively improves the leaching rate of precious metals, its high cost and low yield still cannot be widely used in industry. The prior art still urgently needs a green, non-toxic precious metal leaching agent and precious metal leaching process with high precious metal yield. Summary of the Invention

[0009] In response to the problems existing in the prior art, the first object of the present invention is to provide a thiosulfate-based precious metal leaching agent. Based on the synergistic effect between the various components of the thiosulfate, the precious metal leaching agent not only greatly improves the dissolution efficiency of precious metals but also effectively reduces the production of polysulfate in side reactions, facilitating subsequent precious metal recovery. The iron oxidant effectively improves the leaching kinetics and dissolution of precious metals. Furthermore, under the action of iron ions, thiosulfate can be leached at higher pH values, thereby significantly reducing thiosulfate consumption.

[0010] A second objective of the present invention is to provide a thiosulfate-based precious metal leaching process. By controlling the pH value and leaching agent dosage of the system, this process can leach various grades and types of precious metal-containing materials, particularly heavy metals such as gold and silver, at ambient temperature. The precious metal leachate is then recovered using industry-standard methods, including but not limited to sodium bisulfite addition and filtration or agglomeration, Kennecott cones, Merril-Crowe processes, diatomaceous earth precipitation, and resin-based ion exchange processes. Testing has demonstrated precious metal recovery rates exceeding 90%, with rates as high as 100%.

[0011] To achieve the above technical objectives, the first object of the present invention is to provide a thiosulfate-based precious metal leaching agent, comprising thiosulfate, a thiourea-based catalyst, and an iron-based oxidant, wherein the molar ratio of thiosulfate, thiourea-based catalyst, and iron-based oxidant is 0.05-5:0.005-1:0.005-1. The thiosulfate primarily complexes with the precious metal, followed by directed oxidation by the iron-based oxidant, while the thiourea-based catalyst effectively accelerates the leaching process and prevents passivation. This formulation, based on the synergistic oxidation-complexation-catalysis interaction between the components, achieves an optimal balance between efficient leaching and reagent consumption, while also being environmentally friendly and industrially applicable.

[0012] As a preferred embodiment, the thiosulfate is at least one of sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, barium thiosulfate and calcium thiosulfate.

[0013] As a preferred embodiment, the thiourea-based solvent is at least one of thiourea, thiosemicarbazide and formamidine disulfide.

[0014] As a preferred embodiment, the iron-based oxidizing agent is ferric ethylenediaminetetraacetate and / or ferric diaminocyclohexanetetraacetate.

[0015] The iron-based oxidant used in the present invention is a directional oxidant for gold and does not oxidize with thiosulfate. Under the action of the iron-based oxidant, thiosulfate can be leached under high pH conditions, thereby greatly reducing reagent consumption.

[0016] As a preferred embodiment, when the iron-based oxidant is ferric ethylenediaminetetraacetate, the pH of the leaching system is 6-8.

[0017] As a preferred embodiment, when the iron-based oxidant is diaminocyclohexane ferric tetraacetate, the pH of the leaching system is 8-13.

[0018] The two oxidants, FeEDTA and FeDCTA, have different optimal pH ranges, with the FeDCTA oxidant having a higher optimal pH range. Therefore, when using the FeDCTA oxidant alone, the pH regulator of the system needs to be adjusted to achieve the above-mentioned required pH range of the system.

[0019] As a preferred embodiment, when the iron-based oxidant is ferric ethylenediaminetetraacetate and ferric diaminocyclohexanetetraacetate, the pH of the leaching system is 6-11.

[0020] As a preferred embodiment, when the iron-based oxidant contains ferric ethylenediaminetetraacetate, the regulator required for adjusting the pH is a phosphate buffer or a carbonate buffer.

[0021] The leaching agent provided by the present invention can improve the stability of ore mineralization while stabilizing the pH value of the system by adding a buffer, thereby achieving the versatility of the leaching agent for various types of precious metal ores.

[0022] As a preferred embodiment, when the iron-based oxidant is diaminocyclohexane tetraacetic acid ferric, the regulator required to adjust the pH value is a metal alkali solution.

[0023] As a preferred embodiment, the molar ratio of the iron-based oxidant to the regulator is 0.005-0.5:0.001-0.5.

[0024] As a preferred embodiment, the phosphate buffer is a mixed solution of sodium disodium hydrogen phosphate and sodium dihydrogen phosphate.

[0025] As a preferred embodiment, the carbonate buffer solution is a mixed solution of sodium bicarbonate and sodium carbonate.

[0026] As a preferred embodiment, the metal alkaline solution is one of potassium hydroxide, sodium hydroxide, calcium hydroxide and barium hydroxide.

[0027] As a preferred embodiment, the metal alkali solution is one of potassium hydroxide, sodium hydroxide, calcium hydroxide and barium hydroxide.

[0028] As a preferred embodiment, when the iron-based oxidant is diaminocyclohexane ferric tetraacetate, the leaching agent further contains a chloride additive.

[0029] As a preferred embodiment, the molar ratio of the diaminocyclohexane ferric tetraacetate to the chloride additive is 0.001-0.1:0.01-5.

[0030] As a preferred embodiment, the chloride additive is one of potassium chloride, ferric chloride and sodium chloride.

[0031] The present invention also provides a thiosulfate-based precious metal leaching process, wherein the precious metal sites of a precious metal-containing material are exposed, and then any of the precious metal leaching agents described above is added, the pH value of the leaching system is adjusted to carry out a leaching reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a precious metal leachate.

[0032] The leaching process provided by the present invention is not only applicable to the leaching of precious metal ores of different grades, but is also applicable to any other raw materials containing precious metals, such as gold pillars and PCB boards containing precious metals.

[0033] As a preferred solution, when the precious metal sites in the precious metal-containing material are not directly exposed, the precious metal sites can be exposed by crushing and / or slurrying. It should be noted that pulverizing precious metals in the form of grinding or grinding usually causes the ore to be contaminated by metallic iron in the grinding medium. Since metallic iron consumes FeEDTA / FeDCTA oxidant, it directly affects the leaching results. Therefore, before slurry mixing, magnetic separation or slurry pre-aeration for several hours is required to remove or oxidize the metal in the material.

[0034] As a preferred option, when the precious metal-containing material is a non-concentrated ore, the particle size of the crushed material is 50-5,000 μm. Material size is also crucial; the crushing process must release the precious metal particles from the material to allow the leaching agent to come into contact with them. If the precious metal particles are not released, the leaching agent may not penetrate the barrier layer that penetrates the precious metal surface, hindering the precious metal leaching process and making leaching difficult. Furthermore, due to the high precious metal content in precious metal concentrates, which are more easily exposed, the particle size requirement for precious metal concentrates may not be within the above range.

[0035] As a preferred solution, the concentration of the slurry-adjusted material is 10-70%.

[0036] The leaching reaction conditions are: temperature of 1-80° C., time of 4-96 hours, and system pH of 6-13.

[0037] As a preferred embodiment, the leaching reaction conditions are: temperature of 1-60°C, time of 12-96 hours, and system pH of 6-13. More preferably, the leaching reaction conditions are: temperature of 10-50°C, time of 12-50 hours, and system pH of 6-11.

[0038] The gold recovery rate is negatively correlated with temperature, that is, an increase in temperature will lead to a decrease in the gold recovery rate. However, for precious metal ores, the reaction temperature can be further adjusted according to their grade. The higher the grade of the ore body, the higher the reaction temperature can be.

[0039] As a preferred solution, before recovering the precious metals in the precious metal leachate, an ion exchange process may be used to reduce the solution volume and increase the target metal concentration to form a metal-enriched ion exchange resin eluate, and then the precious metals are recovered.

[0040] As a preferred solution, the precious metal recovery process adopts an industry standard process, which is at least one of the Merrill-Crowe precipitation method, reduction precipitation method, filtration method and cementation sedimentation process.

[0041] As a preferred solution, the reducing agent used in the precious metal recovery process is bisulfite, ascorbic acid, borohydride, hydrazine, hydroxylamine and a combination thereof.

[0042] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are:

[0043] 1) The precious metal leaching agent provided by the present invention is based on the synergistic effect between the various components of the thiosulfate, which not only greatly improves the dissolution efficiency of precious metals, but also effectively reduces the production of polysulfate in the side reaction, facilitating the subsequent recovery of precious metals. Among them, the iron oxidant can effectively improve the leaching kinetics and dissolution of precious metals. At the same time, under the action of iron ions, thiosulfate can be leached at a higher pH value, thereby greatly reducing the consumption of thiosulfate.

[0044] 2) The gold leaching process provided by the present invention can achieve leaching of gold-containing materials of different grades and types under room temperature conditions by controlling the pH value of the system and the amount of leaching agent added. The gold in the gold-rich leachate is then recovered through methods such as the Kennecott cone and Merrill Lynch gold precipitation methods. Tests have shown that the gold recovery rate can reach up to 100% when this process is applied to gold mines.

[0045] 3) In the technical solution provided by the present invention, based on the excellent leaching effect of the leaching agent, no toxic and harmful chemicals such as cyanide and mercury are contained in the entire precious metal leaching process. The tailings obtained after leaching can be directly dry-stacked without the need for a tailings dam, which not only significantly reduces production costs but also fundamentally solves the potential environmental hazards of tailings dam leakage.

[0046] 4) In the technical solution provided by the present invention, by controlling the pH value of the system and the amount of leaching agent, it is possible to achieve leaching of precious metal-containing materials of different grades and types at room temperature, and it can be implemented in working conditions of any scale. DETAILED DESCRIPTION

[0047] To facilitate understanding of the present invention, the present invention will be described in more detail below. It should be noted that the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive work are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a thiosulfate-based precious metal leaching agent composed of the following molar fractions: 0.1 sodium thiosulfate, 0.02 thiourea, and 0.01 FeEDTA.

[0050] The above-mentioned gold leaching agent was used to recover gold from a gold ore with an average grade of 3g / t. The leaching was carried out using a bottle rolling process with a pinhole on the bottle cap. The specific process is as follows:

[0051] 1) Grind and screen the gold ore into 125μm (P80) particles, add water to make a slurry with a solid-liquid ratio of 2:3;

[0052] 2) Adding a gold leaching agent to the ore pulp, wherein the molar concentrations of the leaching agent components in the ore pulp are: sodium thiosulfate 0.1 mol / L, thiourea 0.02 mol / L, FeEDTA 0.01 mol / L, and the ore pulp pH is 6.5-7.5, and then leaching is carried out at room temperature for 30 hours. After solid-liquid separation, a gold leachate is obtained;

[0053] The pH of the system during the leaching process is adjusted by a composition consisting of NaH2PO4 and Na2HPO4 in a molar ratio of 2:1.

[0054] After the gold ore was leached using the leaching agent in this embodiment, the gold recovery rate was 94%.

[0055] Example 2

[0056] This embodiment provides a thiosulfate-based precious metal leaching agent composed of the following molar fractions: 0.85 sodium thiosulfate, 0.025 thiourea, and 0.05 FeEDTA.

[0057] The above-mentioned gold leaching agent was used to recover gold from a gold concentrate with an average grade of 75g / t. Leaching was carried out in a stirred tank reactor and a roller bottle. The specific process was as follows:

[0058] 1) Grind and screen the gold ore into 125μm (P80) particles, add water to make a slurry with a solid-liquid ratio of 2:3;

[0059] 2) Add the gold leaching agent to the slurry. The molar concentrations of the components of the leaching agent in the slurry are: sodium thiosulfate 0.85 mol / L, thiourea 0.025 mol / L, FeEDTA 0.05 mol / L, and the slurry pH is 6.5-7.5. Then, leach for 30 hours at room temperature. After solid-liquid separation, a gold leachate is obtained.

[0060] The pH of the system during the leaching process is adjusted by a composition consisting of NaH2PO4 and Na2HPO4 in a molar ratio of 2:1.

[0061] After leaching the gold ore using the leaching agent of this example, the gold recovery rate was 98%. To prove the consistency of the process, the above process was repeated 4 times, and the average gold recovery rate was 96.9%.

[0062] Furthermore, an excess of soluble reducing agent was added to the gold leaching solution. After sufficient reduction, steel wool was added. The mass volume ratio of steel wool to gold leaching solution was 90 g / L. After slight stirring for 90 minutes, 93% of the gold adhered to the steel wool.

[0063] Example 3

[0064] This embodiment provides a thiosulfate-based precious metal leaching agent composed of the following molar fractions: 0.15 sodium thiosulfate, 0.02 thiourea, and 0.01 FeEDTA.

[0065] The above-mentioned gold leaching agent is used to recover gold from a gold ore with an average grade of 5g / t. The leaching is carried out in a stirred tank reactor. The specific process is as follows:

[0066] 1) Grind and screen the gold ore into 75μm (P95) particles, add water to make slurry with a solid-liquid ratio of 2:3;

[0067] 2) Add the gold leaching agent to the slurry. The molar concentrations of the components of the leaching agent in the slurry are: sodium thiosulfate 0.15 mol / L, thiourea 0.02 mol / L, FeEDTA 0.01 mol / L, and the slurry pH is 6-7.5. Then, leach for 24 hours at room temperature. After solid-liquid separation, a gold leachate is obtained.

[0068] The pH of the system during the leaching process is adjusted by a composition consisting of NaH2PO4 and Na2HPO4 in a molar ratio of 2:1.

[0069] After leaching the gold ore using the leaching agent of this embodiment, the gold recovery rate was 99%.

[0070] Example 4

[0071] This embodiment provides a thiosulfate-based precious metal leaching agent, comprising the following components in molar proportions: 0.125 sodium thiosulfate, 0.02 thiourea, and 0.01 FeCl3; the mass ratio of FeDCTA to FeCl3 in the leaching agent is 2.28:1.

[0072] The above leaching agent is used to recover gold from the gold column. The leaching is carried out in a stirred tank reactor. The specific process is as follows:

[0073] The gold column was placed in a stirred tank reactor and the above-mentioned leaching agent was added. The leaching agent contained 0.125 mol / L sodium thiosulfate, 0.02 mol / L thiourea, and 0.01 mol / L FeCl3. The pH of the system was 9. Then, the gold column was leached at room temperature for 30 hours. After solid-liquid separation, the gold leachate was obtained.

[0074] The pH of the system is adjusted by sodium hydroxide during the leaching process.

[0075] After leaching the gold column using the leaching agent of this embodiment, the gold recovery rate was 88%.

[0076] Example 5

[0077] This embodiment provides a thiosulfate-based precious metal leaching agent, which is composed of the following molar components: 0.125 sodium thiosulfate, 0.025 thiourea, and 0.01 FeDCTA; the mass ratio of FeDCTA to FeCl3 in the leaching agent is 2.28:1, and NaCl is 0.5.

[0078] The above leaching agent was used to recover gold from a gold ore with an average grade of 2.1g / t. The leaching was carried out in a bottle roller. The specific process was as follows:

[0079] 1) Grind and screen the gold ore into 125μm (P80) particles, add water to make a slurry with a solid-liquid ratio of 2:3;

[0080] 2) Adding a gold leaching agent to the slurry, the molar concentrations of the leaching agent components in the slurry are: sodium thiosulfate 0.125 mol / L, thiourea 0.025 mol / L, FeDCTA 0.01 mol / L, NaCl 0.5 mol / L, and the slurry pH is 9.5. Then, leaching is carried out at room temperature for 30 hours. After solid-liquid separation, a gold leachate is obtained.

[0081] The pH of the system is adjusted by sodium hydroxide during the leaching process.

[0082] After leaching gold ore using the leaching agent of this example, the gold recovery rate was 80%. It should be noted that in this example, further increasing the amount of NaCl added will increase the gold leaching rate, but this will promote the decomposition of thiourea into formamidine disulfide. Therefore, the gold recovery rate does not necessarily increase with increasing the amount of NaCl added.

[0083] Example 6

[0084] This embodiment provides a thiosulfate-based precious metal leaching agent, comprising the following components in molar proportions: 0.125 sodium thiosulfate, 0.02 thiourea, and 0.005 FeDCTA; the mass ratio of FeDCTA to FeCl3 in the leaching agent is 2.28:1.

[0085] The gold recovery was carried out using the above-mentioned leaching agent gold column. The leaching was carried out in a stirred tank reactor. The specific process was as follows:

[0086] The gold column was placed in a stirred tank reactor and the above-mentioned leaching agent was added. The leaching agent contained 0.125 mol / L sodium thiosulfate, 0.02 mol / L thiourea, and 0.005 mol / L FeDCTA. The pH of the system was 8-9. The gold column was then leached at room temperature for 24 hours. After solid-liquid separation, a gold leachate was obtained.

[0087] The pH of the system is adjusted by a carbonate buffer during the leaching process.

[0088] After leaching the gold column using the leaching agent of this embodiment, the gold recovery rate was 83%.

[0089] Example 7

[0090] This embodiment provides a thiosulfate-based precious metal leaching agent, comprising the following components in molar proportions: 1.1 sodium thiosulfate, 0.03 thiourea, and 0.09 FeEDTA.

[0091] The above leaching agent was used to recover precious metals from 2.5 kg of high-grade precious metal concentrate with an average grade of 3200 g / t gold and 1550 g / t silver. The leaching was carried out in a bottle roller. The specific process was as follows:

[0092] The above-mentioned precious metal concentrate is directly placed in 50L of leaching solution, the leaching agent contains 1.1mol / L sodium thiosulfate, 0.03mol / L thiourea, and 0.09mol / L FeDCTA, and the pH of the system is 6-7.5. Then, it is leached at room temperature for 48h. After solid-liquid separation, the precious metal leachate is obtained.

[0093] After removing large solids from the precious metal leachate, an excess of reducing agent is added to fully reduce and precipitate the metal. The precipitate is then collected and smelted. The resulting gold ingot has a grade of 65% and a gold recovery rate of 96%. The resulting silver ingot has a grade of 28% and a silver recovery rate of 87%.

Claims

1. A thiosulfate-based precious metal leaching agent, characterized in that: The leaching agent contains thiosulfate, a thiourea-based catalyst and an iron-based oxidant; the molar ratio of the thiosulfate, the thiourea-based catalyst and the iron-based oxidant is 0.05-5:0.005-1:0.005-1.

2. A thiosulfate-based precious metal leaching agent according to claim 1, characterized in that: The thiosulfate is at least one of sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, barium thiosulfate and calcium thiosulfate; the thiourea-based catalyst is at least one of thiourea, thiosemicarbazide and formamidine disulfide.

3. A thiosulfate-based precious metal leaching agent according to claim 1, characterized in that: The iron-based oxidant is ferrous ethylenediaminetetraacetate and / or ferrous diaminecyclohexane tetraacetate; when the iron-based oxidant is ferrous ethylenediaminetetraacetate, the pH of the leaching system is 6-8; when the iron-based oxidant is ferrous diaminocyclohexane tetraacetate, the pH of the leaching system is 8-13; when the iron-based oxidant is ferrous ethylenediaminetetraacetate and ferrous diaminocyclohexane tetraacetate, the pH of the leaching system is 6-11.

4. A thiosulfate-based precious metal leaching agent according to claim 3, characterized in that: When the iron-based oxidant contains ferric ethylenediaminetetraacetate, the regulator required for adjusting the pH is a phosphate buffer or a carbonate buffer; when the iron-based oxidant is ferric diaminocyclohexanetetraacetate, the regulator required for adjusting the pH value is a metal alkali solution.

5. A thiosulfate-based precious metal leaching agent according to claim 4, characterized in that: The molar ratio of the iron-based oxidant to the regulator is 0.005-0.5:0.001-0.5; the phosphate buffer is a mixed solution of sodium disodium hydrogen phosphate and sodium dihydrogen phosphate; the carbonate buffer is a mixed solution of sodium bicarbonate and sodium carbonate; and the metal alkali solution is one of potassium hydroxide, sodium hydroxide, calcium hydroxide and barium hydroxide.

6. A thiosulfate-based precious metal leaching agent according to claim 3, characterized in that: When the iron-based oxidant is diaminocyclohexane tetraacetic acid ferric, the leaching agent further contains a chloride additive; the molar ratio of the diaminocyclohexane tetraacetic acid ferric to the chloride additive is 0.001-0.1:0.01-5; and the chloride additive is one of potassium chloride, ferric chloride and sodium chloride.

7. A thiosulfate-based precious metal leaching process, characterized in that: After the precious metal sites of the precious metal-containing material are exposed, the precious metal leaching agent according to any one of claims 1 to 6 is added, the pH value of the leaching system is adjusted to carry out the leaching reaction, and after the reaction is completed, the precious metal leaching solution is obtained by solid-liquid separation.

8. A thiosulfate-based precious metal leaching process according to claim 7, characterized in that: When the precious metal sites in the precious metal-containing material are not directly exposed, the precious metal sites can be exposed by crushing and / or slurrying; when the precious metal-containing material is a non-concentrate, the particle size of the crushed material is 50~5000μm; the concentration of the material after slurrying is 10~70%.

9. A thiosulfate-based precious metal leaching process according to claim 7, characterized in that: The leaching reaction occurs at the contact of the leaching agent with the precious metal sites in the comminuted material.

10. A thiosulfate-based precious metal leaching process according to claim 7, characterized in that: The leaching reaction conditions are: temperature of 1-80° C., time of 4-96 hours, and system pH of 6-13.

11. The thiosulfate-based precious metal leaching process according to claim 7, characterized in that: The leaching reaction conditions are: temperature of 1-60° C., time of 12-96 hours, and system pH of 6-13.

12. The thiosulfate-based precious metal leaching process according to claim 7, characterized in that: Before recovering the precious metals in the precious metal leachate, an ion exchange process can be used to reduce the solution volume and increase the target metal concentration to form a metal-enriched ion exchange resin eluate, and then the precious metals can be recovered.

13. The thiosulfate-based precious metal leaching process according to claim 12, characterized in that: The precious metal recovery process adopts an industry standard process, which is at least one of the Merrill-Crowe precipitation method, reduction precipitation method, filtration method and cementation deposition process; the reducing agent used in the precious metal recovery process is bisulfite, ascorbic acid, borohydride, hydrazine, hydroxylamine and a combination thereof.