Method for smelting and extracting gold from low-gold pyrite

Abstract

The invention discloses a method for smelting and extracting gold from low-gold pyrite, which comprises the following steps of: independently oxidizing and smelting low-grade gold-containing pyrite by utilizing the metalloid property of molten ferrous sulfide, enriching valuable elements such as gold in the ore in a molten ferrous sulfide phase through selective slagging, and realizing the enrichment and recovery of valuable metals such as gold in the ore. The method is not limited by other auxiliary materials such as copper, lead and antimony and can be singly smelted on a large scale, so that the problem that low-grade gold-containing pyrite in remote areas is difficult to dispose is solved; through dual regulation and control of gold-rich ferrous sulfide phase acid leaching and acid leaching residue pulp mixing, the concentration of iron ions in acid leaching residue biological oxidation ore pulp is controlled to be smaller than 45 g / L, the biological oxidation effect of gold-rich acid leaching residues is guaranteed, meanwhile, a byproduct ferrous sulfate is produced, and the comprehensive economic benefits of the process are improved. After the gold-rich ferrous sulfide phase is subjected to'acid leaching + biological oxidation-gold leaching 'treatment, gold leaching residues mainly contain iron oxide, the iron grade is higher than 65%, the gold leaching residues can be fed into an iron and steel plant to be treated, and comprehensive recovery of the iron element in the gold-containing pyrite is achieved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method for smelting and extracting gold from low-gold-sulfur iron ore. Background Technology

[0002] Gold is a very important rare and precious metal, one of the most malleable metals in nature. Due to its scarcity in the earth's crust and its stable properties, it is a special strategic reserve material with both monetary and commodity attributes, and is now widely used in aerospace, nuclear industry, electronic equipment and many other fields.

[0003] Mineralized gold remains the primary source of gold. However, with the continuous expansion of gold mining, high-quality, easily processed gold ores are becoming increasingly depleted. Statistics show that refractory gold ores account for 60%-70% of all proven gold deposits worldwide, gradually becoming one of the main raw materials for gold production companies. Generally, if a certain ore cannot achieve a satisfactory gold cyanide leaching rate (>80%) even after fine grinding, it can be called a refractory gold ore. To improve the gold recovery rate of refractory gold ores, pretreatment is often performed before cyanide extraction. Commonly used pretreatment methods include roasting oxidation, pressure oxidation, and biological oxidation, but these still have certain limitations, such as for fine-grained, low-gold, high-sulfur gold ores and silicate-encapsulated gold ores. Therefore, some scholars have proposed pyrometallurgical gold extraction processes, which involve mixing refractory gold ores with other metallic materials for smelting, enriching the gold in matte or other metallic materials.

[0004] Chinese patent applications CN101519731A (Method for extracting multiple elements from high-arsenic complex gold concentrate) and CN107119195A (Method for recovering gold and copper by direct smelting of high-S and high-Fe gold ore and copper-containing waste) both involve mixing and smelting gold ore with copper-containing materials to enrich gold in copper matte.

[0005] Chinese patent applications CN104313328A (Method for recovering lead and gold by reducing and solidifying a molten pool based on refractory gold ore and lead-containing waste residue raw materials), CN107058758A (A two-step smelting method for recovering gold and lead from high-S, high-Fe, Pb-containing gold ore), and CN102312107 A (A smelting method for Carlin-type gold ore) all involve mixing and smelting gold ore with lead-containing materials to enrich gold in crude lead.

[0006] Chinese patent application CN102051491A (A method for enriching gold in pyrite-encapsulated gold ore) describes a method of mixing and smelting gold ore with coke and a reducing agent to enrich gold in pig iron.

[0007] Chinese patent applications CN103243221A (A method for directly smelting and enriching gold from antimony-arsenic-containing refractory gold ore), CN108823425A (A method for molten extraction and enrichment of gold from refractory gold ore), and CN110373539A (A method for enhanced enrichment of gold from direct smelting of refractory gold ore) propose mixing refractory gold ore with antimony sources for smelting, thereby enriching gold in antimony matte.

[0008] The above research results indicate that mixing and oxidizing refractory gold ore with raw materials such as copper, lead, and antimony is an ideal method for gold extraction. However, it is still limited by other smelting raw materials. In the face of large quantities of low-grade gold-bearing pyrite, existing processes are still difficult to handle economically. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention aims to provide a method for smelting and extracting gold from low-gold pyrite.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for smelting and extracting gold from low-gold pyrite includes the following steps:

[0012] Step 1: Oxidation and smelting of gold-bearing pyrite:

[0013] Gold-bearing pyrite, flux, and reducing agent are fed into a smelting furnace for oxidative smelting. After the oxidative smelting is completed, the resulting mixed melt is sent to an electric furnace for depletion to obtain depleted slag and gold-rich ferrous sulfide. The sulfur-containing flue gas generated by the oxidative smelting is sent to an acid production system to prepare sulfuric acid.

[0014] Step 2: Acid leaching of the gold-rich ferrous sulfide phase:

[0015] Using sulfuric acid obtained from the flue gas acid production system as a leaching agent, finely ground ferrous sulfide was acid-leached to obtain ferrous acid leaching residue and hydrated ferrous sulfate products.

[0016] Step 3: Bio-oxidation of the rich-gold acid leaching residue:

[0017] Pre-oxidizing bacteria are added to a dilute acid solution to prepare a biological oxidation solution. The biological oxidation solution is then mixed with the acid leaching residue to form a slurry for biological pre-oxidation of the acid leaching residue, thus obtaining biological oxidation residue.

[0018] Step 4: Cyanide extraction of gold from bio-oxidation residue:

[0019] The biological oxidation residue is mixed with water and lime to form a slurry, which is then fed into the cyanide gold extraction system.

[0020] Step 5, Liquid-solid separation:

[0021] After cyanide extraction, the resulting cyanide slurry undergoes liquid-solid separation. The gold-leaching residue is sent to the iron and steel smelting system, while the gold-loaded carbon is sent to the gold smelting system.

[0022] Further, in step 1, the flux includes one or more of CaO, CaCO3, CaSO4, calcium borate, and silicon dioxide; the reducing agent includes one or more of coke powder, coal powder, and biomass.

[0023] Furthermore, in the oxidation smelting process of gold-bearing pyrite in step 1, the reducing agent ratio is 1-5% of the mass of gold-bearing pyrite.

[0024] Furthermore, in step 1, the oxidation smelting temperature is 1300-1350℃, the mass ratio of the depleted slag to the gold-rich ferrous sulfide phase is 2.5-6:1; the mass ratio of Fe to SiO2 in the depleted slag is 1-1.3:1, the mass ratio of CaO to SiO2 is 0.2-0.3:1, and the mass content of Al2O3 is less than 12%.

[0025] Furthermore, in step 1, 0-3% of a reducing agent by mass of the mixed melt is added during the depletion process in the electric furnace. The reducing agent includes one or more of the following: coke powder, coal powder, biomass, natural gas, and biomass oil.

[0026] Furthermore, in step 1, the conditions for depletion in the electric furnace are to maintain the temperature at 1300℃-1350℃ for 1-3 hours.

[0027] Furthermore, in step 2, the finely ground ferrous sulfide has a particle size of -74μm accounting for 50-90%, the sulfuric acid mass concentration of the leaching agent is 10-30%, and the leaching temperature is ≥80℃.

[0028] Furthermore, in step 3, the iron ion concentration in the slurry obtained by mixing the bio-oxidation solution with the ferrous acid leaching residue is less than 45 g / L; the pre-oxidation bacteria are thermophilic mesophilic sulfur-oxidizing bacteria, and their addition amount accounts for 20-40% of the total volume of the bio-oxidation solution; the reaction temperature of bio-oxidation is 35-45℃, the pH is 1-1.5, and the reaction time is 7-14 days.

[0029] Furthermore, in step 4, the bio-oxidation residue is slurried with water and lime to a pH value of 11.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) This invention utilizes the metalloid properties of molten ferrous sulfide to separately oxidize and smelt low-grade gold-bearing pyrite. Through selective slag formation, valuable elements such as gold in the ore are enriched in the molten ferrous sulfide phase, thereby achieving the enrichment and recovery of valuable metals such as gold in the ore. It is not limited by other auxiliary materials such as copper, lead, and antimony, and can be smelted and processed in large quantities separately, solving the problem of difficult disposal of low-grade gold-bearing pyrite in remote areas.

[0032] (2) This invention targets the high iron content of ferrous sulfide, and through the dual regulation of "ferrous sulfide phase acid leaching + acid leaching residue slurry conditioning", the iron ion concentration of the acid leaching residue bio-oxidation slurry is controlled to be less than 45 g / L. While achieving good bio-oxidation effect, ferrous sulfate by-product is produced, which improves the overall economic benefits of the process.

[0033] (3) After the gold-rich ferrous sulfide phase is treated by "acid leaching + biological oxidation - gold leaching", the gold leaching residue is mainly iron oxide with an iron grade of >65%, which can be sent to the steel plant for processing to achieve comprehensive recovery of iron elements in gold-bearing pyrite. Attached Figure Description

[0034] Figure 1 The following are flowcharts of the methods in embodiments 1-4 of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0036] Example 1

[0037] This embodiment provides a method for smelting and extracting gold from low-gold pyrite. The main mass percentage contents of the gold-bearing pyrite used are: Fe 31.82%, S 32.2%, Cu 0.55%, SiO2 20.4%, Al2O3 5.3%, CaO 2.4%, Au 5.5g / t.

[0038] like Figure 1 As shown, the method in this embodiment includes the following steps:

[0039] (1) Smelting of gold-bearing pyrite: The above-mentioned gold-bearing pyrite, along with 1.68% CaO and 1% coal powder by weight of the gold-bearing pyrite, are fed into a smelting furnace. Oxidation smelting is carried out at 1300℃ with oxygen-enriched gas at an oxygen concentration of 70%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the slag is 1:1, the mass ratio of CaO to SiO2 is 0.2:1, and the Al2O3 content in the slag is about 10.5%. After the oxidation smelting is completed, the mixed melt is sent to the electric furnace depletion process. Under the depletion condition of holding at 1300℃ for 1 hour, the two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is achieved. The mass ratio of the depleted slag and the gold-rich ferrous sulfide phase is about 2.5. The gold grade of the gold-rich ferrous sulfide phase is about 25.8 g / t, the gold grade in the depleted slag is about 0.45 g / t, and the direct gold recovery rate of smelting is about 95.8%. The sulfur-containing flue gas generated during the oxidative smelting process is fed into the acid production system to prepare sulfuric acid.

[0040] (2) Acid leaching of gold-rich ferrous sulfide phase: Gold-rich ferrous sulfide was finely ground to -74μm with a content of 50%. A 10% concentration of sulfuric acid was used as the leaching agent, and the gold-rich ferrous sulfide phase was acid-leached at 80℃ with stirring for 2 hours to obtain gold-rich acid leaching residue and ferrous sulfate heptahydrate product. The gold content of the gold-rich acid leaching residue was approximately 34.3 g / t.

[0041] (3) Bio-oxidation of acid leaching residue: Thermophilic mesophilic sulfur oxidizing bacteria were added to a dilute acid solution to prepare a bio-oxidation solution. The amount of thermophilic mesophilic sulfur oxidizing bacteria added was 20% of the total volume of the bio-oxidation solution. Subsequently, the bio-oxidation solution was mixed with gold-rich acid leaching residue to form a slurry for bio-oxidation. In terms of oxidation conditions, the total iron ion concentration in the slurry obtained by mixing the bio-oxidation solution with gold-rich acid leaching residue was about 43 g / L, the oxidation temperature was 45℃, the slurry pH was 1.5, and the oxidation time was 14 days. Finally, a bio-oxidation residue with a gold grade of about 40.2 g / t was produced, and the sulfur oxidation rate was about 96.4%.

[0042] (4) Cyanide extraction of gold from biological oxidation residue: After adding water to the biological oxidation residue, the pH value is adjusted to 11 with lime and then sent to the cyanide extraction system. Sodium cyanide and carbon are added to carry out cyanide extraction of gold, and the gold leaching rate is about 98.6%.

[0043] (5) Liquid-solid separation: After the cyanide gold extraction is completed, the cyanide slurry is separated into liquid and solid to obtain gold leaching residue and gold-loaded carbon. The gold leaching residue is sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0044] Example 2

[0045] This embodiment provides a method for smelting and extracting gold from low-gold pyrite. The main mass percentage contents of the gold-bearing pyrite used are: Fe 31.82%, S 32.2%, Cu 0.55%, SiO2 20.4%, Al2O3 5.3%, CaO 2.4%, Au 5.5g / t.

[0046] like Figure 1 As shown, the method in this embodiment includes the following steps:

[0047] (1) Smelting of gold-bearing pyrite: The above-mentioned gold-bearing pyrite, along with 3.7% CaO and 1% coal powder by weight of the gold-bearing pyrite, are fed into a smelting furnace. Oxidative smelting is carried out at 1350℃ using oxygen-enriched gas with an oxygen concentration of 70%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the slag is 1.3:1, the mass ratio of CaO to SiO2 is 0.3:1, and the Al2O3 content in the slag is about 8%. After the oxidative smelting is completed, the mixed melt is sent to the electric furnace depletion process. Under the depletion condition of holding at 1350℃ for 1 hour, the two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is achieved. The mass ratio of the depleted slag to the gold-rich ferrous sulfide phase is about 6, the gold grade of the gold-rich ferrous sulfide is about 49.4 g / t, the gold grade in the depleted slag is about 0.5 g / t, and the direct gold recovery rate is about 94.1%. The sulfur-containing flue gas generated during the oxidative smelting process is fed into the acid production system to prepare sulfuric acid.

[0048] (2) Acid leaching of gold-rich ferrous sulfide phase: Gold-rich ferrous sulfide was finely ground to -74μm with a content of 90%. Using 30% sulfuric acid as the leaching agent, the gold-rich ferrous sulfide phase was acid-leached at 80℃ with stirring for 4 hours to obtain gold-rich acid leaching residue and ferrous sulfate heptahydrate product. The gold content of the gold-rich acid leaching residue was approximately 65.1 g / t.

[0049] (3) Bio-oxidation of acid leaching residue: Thermophilic mesophilic sulfur-oxidizing bacteria were added to a dilute acid solution to prepare a bio-oxidation solution. The amount of thermophilic mesophilic sulfur-oxidizing bacteria added was 40% of the total volume of the bio-oxidation solution. Subsequently, the bio-oxidation solution was mixed with gold-rich acid leaching residue to form a slurry for bio-oxidation. In terms of oxidation conditions, the total iron ion concentration in the slurry obtained by mixing the bio-oxidation solution with gold-rich acid leaching residue was about 40 g / L, the oxidation temperature was 35℃, the slurry pH was 1, and the oxidation time was 12 days. Finally, a bio-oxidation residue with a gold grade of about 73.1 g / t was produced, and the sulfur oxidation rate was about 95.8%.

[0050] (4) Cyanide extraction of gold from biological oxidation residue: After adding water to the biological oxidation residue, the pH value is adjusted to 11 with lime and then sent to the cyanide extraction system. Sodium cyanide and carbon are added to carry out cyanide extraction of gold, and the gold leaching rate is about 98.1%.

[0051] (5) Liquid-solid separation: After the cyanide gold extraction is completed, the cyanide slurry is separated into liquid and solid to obtain gold leaching residue and gold-loaded carbon. The gold leaching residue is sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0052] Example 3

[0053] This embodiment provides a method for smelting and extracting gold from low-gold pyrite. The main mass percentage contents of the gold-bearing pyrite used are: Fe 31.82%, S 32.2%, Cu 0.55%, SiO2 20.4%, Al2O3 5.3%, CaO 2.4%, Au 5.5g / t.

[0054] like Figure 1 As shown, the method in this embodiment includes the following steps:

[0055] (1) Smelting of gold-bearing pyrite: The gold-bearing pyrite, along with 2.7% CaO and 5% pulverized coal by weight of the gold-bearing pyrite, is fed into a smelting furnace. Oxidative smelting is carried out at 1350℃ using oxygen-enriched gas with an oxygen concentration of 70%. For slag shape control, the mass ratio of Fe to SiO2 in the slag is 1:1, the mass ratio of CaO to SiO2 is 0.25:1, and the Al2O3 content in the slag is approximately 10%. After oxidative smelting, the mixed melt is sent to an electric furnace for depletion. Under depletion conditions of 1300℃, pulverized coal ratio of 1% of the mixed melt mass, and holding for 2 hours, two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is achieved. The mass ratio of the depleted slag to the gold-rich ferrous sulfide is approximately 2.5, the gold grade of the gold-rich ferrous sulfide is approximately 24.4 g / t, the gold grade in the depleted slag is approximately 0.39 g / t, and the direct gold recovery rate is approximately 96.2%. The sulfur-containing flue gas generated during the oxidative smelting process is fed into the acid production system to prepare sulfuric acid.

[0056] (2) Acid leaching of gold-rich ferrous sulfide: Gold-rich ferrous sulfide was finely ground to -74μm with a content of 50%. A 10% concentration of sulfuric acid was used as the leaching agent, and the gold-rich ferrous sulfide phase was acid-leached at 80℃ with stirring for 2 hours to obtain gold-rich acid leaching residue and ferrous sulfate heptahydrate product. The gold content of the gold-rich acid leaching residue was approximately 32.1 g / t.

[0057] (3) Bio-oxidation of acid leaching residue: A bio-oxidation solution was prepared by adding thermophilic mesophilic sulfur-oxidizing bacteria to a dilute acid solution. The amount of thermophilic mesophilic sulfur-oxidizing bacteria added was 25% of the total volume of the bio-oxidation solution. Subsequently, the bio-oxidation solution was mixed with gold-rich acid leaching residue to form a slurry for bio-oxidation. In terms of oxidation conditions, the total iron ion concentration in the slurry obtained by mixing the bio-oxidation solution and gold-rich acid leaching residue was about 42 g / L, the oxidation temperature was 45℃, the slurry pH was 1.5, and the oxidation time was 10 days. The final product was a bio-oxidation residue with a gold grade of about 37.3 g / t and a sulfur oxidation rate of about 95.4%.

[0058] (4) Cyanide extraction of gold from biological oxidation residue: After adding water to the biological oxidation residue, the pH value is adjusted to 11 with lime and then sent to the cyanide extraction system. Sodium cyanide and carbon are added to carry out cyanide extraction of gold, and the gold leaching rate is about 98.6%.

[0059] (5) Liquid-solid separation: After the cyanide gold extraction is completed, the cyanide slurry is separated into liquid and solid to obtain gold leaching residue and gold-loaded carbon. The gold leaching residue is sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0060] Example 4

[0061] This embodiment provides a method for smelting and extracting gold from low-gold pyrite. The main mass percentage contents of the gold-bearing pyrite used are: Fe 31.82%, S 32.2%, Cu 0.55%, SiO2 20.4%, Al2O3 5.3%, CaO 2.4%, Au 5.5g / t.

[0062] like Figure 1 As shown, the method in this embodiment includes the following steps:

[0063] (1) Smelting of gold-bearing pyrite: The above-mentioned gold-bearing pyrite, along with 5.68% SiO2, 5.42% CaO, and 3% coal powder by weight of the gold-bearing pyrite, are fed into a smelting furnace. Oxidation smelting is carried out at 1350℃ with oxygen-enriched gas at an oxygen concentration of 70%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the slag is 1:1, the mass ratio of CaO to SiO2 is 0.3:1, and the Al2O3 content in the slag is about 8%. After oxidation smelting, the mixed melt is fed into an electric furnace depletion process. Under depletion conditions of 1300℃, holding for 3 hours, and a pulverized coal ratio of 3% of the mixed melt mass, the depleted slag and the gold-rich ferrous sulfide phase are separated. The mass ratio of the depleted slag to the gold-rich ferrous sulfide phase is approximately 6. The gold content of the gold-rich ferrous sulfide phase is approximately 47.5 g / t, and the gold content of the depleted slag is approximately 0.07 g / t. The direct gold recovery rate is approximately 98.7%. The sulfur-containing flue gas generated during oxidation smelting is fed into the acid production system to prepare sulfuric acid.

[0064] (2) Acid leaching of gold-rich ferrous sulfide: Gold-rich ferrous sulfide was finely ground to -74μm (90% of the product). Using 20% ​​sulfuric acid as the leaching agent, the gold-rich ferrous sulfide was acid-leached at 80℃ with stirring for 3 hours to obtain gold-rich acid leaching residue and ferrous sulfate heptahydrate product. The gold content of the gold-rich acid leaching residue was approximately 62.9 g / t.

[0065] (3) Bio-oxidation of acid leaching residue: Thermophilic mesophilic sulfur-oxidizing bacteria were added to a dilute acid solution to prepare a bio-oxidation solution. The amount of thermophilic mesophilic sulfur-oxidizing bacteria added was 35% of the total volume of the bio-oxidation solution. Subsequently, the bio-oxidation solution was mixed with gold-rich acid leaching residue to form a slurry for bio-oxidation. In terms of oxidation conditions, the total iron ion concentration in the slurry obtained by mixing the bio-oxidation solution and gold-rich acid leaching residue was about 40 g / L, the oxidation temperature was 35℃, the slurry pH was 1, and the oxidation time was 7 days. The final product was bio-oxidized residue with a gold grade of about 71.4 g / t and a sulfur oxidation rate of about 95.9%.

[0066] (4) Cyanide extraction of gold from biological oxidation residue: After adding water to the biological oxidation residue, the pH value is adjusted to 11 with lime and then sent to the cyanide extraction system. Sodium cyanide and carbon are added to carry out cyanide extraction of gold, and the gold leaching rate is about 98.3%.

[0067] (5) Liquid-solid separation: After the cyanide gold extraction is completed, the cyanide slurry is separated into liquid and solid to obtain gold leaching residue and gold-loaded carbon. The gold leaching residue is sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0068] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A method for smelting and extracting gold from low-gold pyrite, characterized in that, Includes the following steps: Step 1: Oxidation and smelting of gold-bearing pyrite: Gold-bearing pyrite, flux, and reducing agent are fed into a smelting furnace for oxidative smelting. After the oxidative smelting is completed, the resulting mixed melt is sent to an electric furnace for depletion to obtain depleted slag and gold-rich ferrous sulfide. The sulfur-containing flue gas generated by the oxidative smelting is sent to an acid production system to prepare sulfuric acid. Step 2: Acid leaching of the gold-rich ferrous sulfide phase: Using sulfuric acid obtained from the flue gas acid production system as a leaching agent, finely ground ferrous sulfide was acid-leached to obtain ferrous acid leaching residue and hydrated ferrous sulfate products. Step 3: Bio-oxidation of the rich-gold acid leaching residue: Pre-oxidizing bacteria are added to a dilute acid solution to prepare a biological oxidation solution. The biological oxidation solution is then mixed with the acid leaching residue to form a slurry for biological pre-oxidation of the acid leaching residue, thus obtaining biological oxidation residue. Step 4: Cyanide extraction of gold from bio-oxidation residue: The biological oxidation residue is mixed with water and lime to form a slurry, which is then fed into the cyanide gold extraction system. Step 5, Liquid-solid separation: After cyanide extraction, the resulting cyanide slurry undergoes liquid-solid separation. The gold-leaching residue is sent to the iron and steel smelting system, while the gold-loaded carbon is sent to the gold smelting system.

2. The method according to claim 1, characterized in that, In step 1, the flux includes one or more of CaO, CaCO3, CaSO4, calcium borate, and silicon dioxide; the reducing agent includes one or more of coke powder, coal powder, and biomass.

3. The method according to claim 1, characterized in that, In the oxidation smelting process of gold-bearing pyrite in step 1, the reducing agent ratio is 1-5% of the mass of gold-bearing pyrite.

4. The method according to claim 1, characterized in that, In step 1, the oxidation smelting temperature is 1300-1350℃, the mass ratio of lean slag to gold-rich ferrous sulfide phase is 2.5-6:1; the mass ratio of Fe to SiO2 in the lean slag is 1-1.3:1, the mass ratio of CaO to SiO2 is 0.2-0.3:1, and the mass content of Al2O3 is less than 12%.

5. The method according to claim 1, characterized in that, In step 1, 0-3% of a reducing agent by mass of the mixed melt is added during the leaning process in the electric furnace. The reducing agent includes one or more of the following: coke powder, coal powder, biomass, natural gas, and biomass oil.

6. The method according to claim 1, characterized in that, In step 1, the conditions for depletion in the electric furnace are to maintain the temperature at 1300℃-1350℃ for 1-3 hours.

7. The method according to claim 1, characterized in that, In step 2, the fine grinding particle size of the gold-rich ferrous sulfide is -74μm, accounting for 50-90%, the sulfuric acid mass concentration of the leaching agent is 10-30%, and the leaching temperature is ≥80℃.

8. The method according to claim 1, characterized in that, In step 3, the iron ion concentration in the slurry obtained by mixing the bio-oxidation solution with the ferrous acid leaching residue is less than 45 g / L; the pre-oxidation bacteria are thermophilic mesophilic sulfur-oxidizing bacteria, and their addition accounts for 20-40% of the total volume of the bio-oxidation solution; the reaction temperature of bio-oxidation is 35-45℃, the pH is 1-1.5, and the reaction time is 7-14 days.

9. The method according to claim 1, characterized in that, In step 4, the bio-oxidation residue is mixed with water and lime to adjust the pH value to 11.

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