Efficient gold extraction method for low-gold pyrite

Abstract

The invention discloses a high-efficiency gold extraction method of low-gold pyrite, which comprises the following steps of: independently oxidizing and smelting the 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, can be used for large-scale independent smelting treatment, and solves the problem that low-grade gold-containing pyrite in remote areas is difficult to dispose. After the low-gold pyrite is subjected to smelting pretreatment, flue gas can be used for preparing acid, the produced gold-rich ferrous sulfide phase is fed into a hot-pressing oxidation-cyaniding gold extraction system, pre-acidification treatment is not needed before hot-pressing oxidation, and the neutralization cost is greatly reduced. And after the oxidation liquid is neutralized by lime, neutralized slag can be returned to the smelting process for recycling, so that the smelting cost is reduced. The cyanidation gold leaching residues mainly comprise high-purity iron oxide, the iron grade is higher than 65%, the cyanidation gold leaching residues can be fed into an iron and steel plant to be treated, and efficient utilization 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 an efficient method for extracting gold from low-gold sulfide iron ore. Background Technology

[0002] As gold mining scale continues to expand, high-quality, easily processed gold ore is becoming increasingly depleted, and refractory gold ore is gradually becoming one of the main raw materials for gold production enterprises. To improve the gold recovery rate of refractory gold ore, it is often pretreated before cyanidation gold extraction. Current gold ore pretreatment processes mainly include roasting, hot-press oxidation, and biological oxidation. However, for low-grade, low-gold pyrite ores, existing processes are still difficult to handle economically.

[0003] The roasting method mainly involves high-temperature oxidation of minerals, which causes sulfides to oxidize and decompose, carbonaceous materials to be burned off or passivated, and the encapsulation structure to expose gold. However, when the sulfur content of the gold ore is too high, the roasting temperature is difficult to control, which can easily lead to the gold being encapsulated again by molten silicates, reducing the gold recovery rate.

[0004] Pressure oxidation, performed under high temperature and pressure, uses oxygen or air as an oxidant to oxidize sulfides in acidic or alkaline media, converting them into sulfates and hematite, thus fully liberating the gold. However, the processing cost is high, making it economically unfeasible when the gold grade is low and the sulfur grade is high.

[0005] Biological oxidation utilizes acidophilic, thermophilic, or zetaphilic microorganisms to catalyze the oxidation of sulfides in acidic aqueous solutions. However, when the gold grade is low and the sulfur grade is high, the oxidation rate decreases further, making it difficult to process effectively.

[0006] To address this issue, modern industrial production often involves smelting low-gold pyrite with copper, lead, nickel, and other ores. However, the large annual output of low-gold pyrite cannot be absorbed by copper and lead smelters. Therefore, developing an efficient method for extracting gold from low-gold pyrite is of great research significance.

[0007] Mixing and oxidizing refractory gold ore with raw materials such as copper, lead, and antimony is an ideal method for gold extraction, but it is still limited by other smelting raw materials. Existing processes are still difficult to handle economically when dealing with large quantities of low-grade, low-gold, low-sulfur iron ore. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention aims to provide an efficient method for extracting gold from low-gold pyrite.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] An efficient method for extracting gold from low-gold pyrite includes the following steps:

[0011] Step 1: Oxidation smelting of low-gold pyrite:

[0012] Low-gold pyrite, flux and reducing agent are fed into a smelting furnace for oxidation smelting. The resulting mixed melt is then depleted in an electric furnace to obtain gold-rich ferrous sulfide phase, depleted slag and sulfur-containing flue gas. The sulfur-containing flue gas is then fed into a flue gas sulfuric acid production system to prepare sulfuric acid.

[0013] Step 2: Hot-press oxidation of the rich-gold acid leaching residue:

[0014] After being finely ground and slurried, the gold-rich ferrous sulfide phase is sent to a hot-press oxidation system for oxidation pretreatment to obtain oxidation slag and oxidation liquid.

[0015] Step 3: Cyanide extraction of gold from oxide residue:

[0016] After washing and slurry preparation, the oxide residue is sent to the cyanide gold extraction system to obtain gold-loaded carbon and cyanide tailings. The gold-loaded carbon is sent to the gold smelting system, and the cyanide tailings are sent to the iron and steel smelting system.

[0017] Further, in step 1, the flux is one or more of CaO, CaCO3, CaSO4, calcium borate, and quartz; the reducing agent is one or more of coke powder, coal powder, and biomass; and the amount of reducing agent used is 0-5% of the mass of the low-gold pyrite.

[0018] Furthermore, in step 1, the 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 percentage of Al2O3 is less than 12%.

[0019] Furthermore, in step 1, 0-3% of the mass of the mixed melt obtained by oxidative smelting is added to the mixed melt during the electric furnace depletion process. The reducing agent is one or more of coke powder, coal powder, biomass, natural gas, and biomass oil.

[0020] Furthermore, in step 1, the conditions for depletion in the electric furnace are to maintain the temperature at 1300℃ for 1-2 hours.

[0021] Furthermore, in step 2, the finely ground ferrous sulfide phase has a particle size of -74μm accounting for 50-90%, and the mass concentration of the slurry is 10-30%; the hot pressing oxidation temperature is 195-220℃, the oxygen partial pressure is 0.4-0.8MPa, and the reaction time is 1-3h.

[0022] Furthermore, the oxidizing liquid obtained in step 2 is neutralized with lime to obtain a neutralized liquid and gypsum residue. The gypsum residue can be returned as a flux to participate in the oxidation smelting process.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) By utilizing the metalloid properties of molten ferrous sulfide, low-grade gold-bearing pyrite can be oxidized and smelted separately. 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.

[0025] (2) Compared with the conventional hot-pressing oxidation process for gold mines, the flue gas from low-gold pyrite ore can be used to produce acid after smelting pretreatment. The resulting gold-rich ferrous sulfide phase does not require pre-acidification treatment, which greatly reduces the neutralization cost. After the oxidation liquid is neutralized with lime, the neutralization slag can be returned to the smelting process for recycling, further reducing smelting costs.

[0026] (3) After the gold-rich ferrous sulfide phase is treated by "hot pressing oxidation-gold leaching", the gold leaching residue is mainly composed of high-purity iron oxide with an iron grade of >65%, which can be sent to steel plants for processing to realize the efficient utilization of iron elements in gold-bearing pyrite. Attached Figure Description

[0027] Figure 1 The flowcharts are for the methods in Embodiments 1-4 of the present invention. Detailed Implementation

[0028] 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.

[0029] Example 1

[0030] This embodiment provides an efficient method for gold extraction from low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are: Fe 32.3%, S 33.4%, Cu 0.26%, SiO2 20.54%, Al2O3 3.48%, CaO 1.1%, Au 8.4 g / t.

[0031] like Figure 1 As shown, the method includes the following steps:

[0032] (1) Smelting of low-gold pyrite: The above-mentioned low-gold pyrite and 3% CaO by weight of the low-gold pyrite are fed into a smelting furnace and oxidized and smelted at 1350℃ with oxygen-enriched gas with an oxygen concentration of 80%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the slag is 1:1, and the mass ratio of CaO to SiO2 is 0.2:1. ，The Al2O3 content in the slag is approximately 6.7%. After oxidation smelting, the mixed melt is fed into an electric furnace depletion process. Under depletion conditions of holding at 1300℃ for 1 hour, 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 2.5. The gold content in the resulting ferrous sulfide phase is approximately 39.5 g / t, and the gold content in the depleted slag is approximately 0.52 g / t, with a gold recovery rate of approximately 96.8%. The sulfur-containing flue gas is then fed into a flue gas sulfuric acid production system to prepare sulfuric acid.

[0033] (2) Hot-press oxidation of gold-rich ferrous sulfide phase: The gold-rich ferrous sulfide phase is finely ground to -74μm, accounting for 50%. Water is added to adjust the slurry mass concentration to 30%, and then fed into the hot-press oxidation system. Hot-press oxidation is carried out under the conditions of hot-pressing temperature of 195℃, oxygen partial pressure of 0.8MPa, and holding time of 3h to obtain oxidation slag and oxidation liquid. The sulfur oxidation rate is about 94%, and the gold content of the oxidation slag is about 46.3g / t. The oxidation liquid is neutralized with lime to obtain neutralized liquid and gypsum slag. The gypsum slag is returned as a flux to participate in the oxidation smelting process.

[0034] (3) Oxidation residue cyanide gold extraction: After washing the oxidation residue, water is added, and the pH value of the slurry is adjusted to 11 with lime. Then it is sent to the cyanide gold extraction system, and the final gold leaching rate is about 97.6%.

[0035] (4) Liquid-solid separation: After liquid-solid separation of cyanide slurry, gold leaching residue is sent to the iron and steel smelting system, and gold-loaded carbon is sent to the gold smelting system.

[0036] Example 2

[0037] This embodiment provides an efficient method for gold extraction from low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are: Fe 32.3%, S 33.4%, Cu 0.26%, SiO2 20.54%, Al2O3 3.48%, CaO 1.1%, Au 8.4g / t.

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

[0039] (1) Smelting of low-gold pyrite: The aforementioned low-gold pyrite, along with 5% CaO and 1% coal powder by weight of the low-gold pyrite, are fed into a smelting furnace and oxidized at 1300℃ using oxygen-enriched gas with an oxygen concentration of 80%. For slag control, the mass ratio of Fe to SiO2 in the depleted slag is 1:1, the mass ratio of CaO to SiO2 is 0.3:1, and the Al2O3 content in the slag is approximately 6.6%. After oxidative smelting, the mixed melt is fed into an electric furnace depletion process. Under depletion conditions of holding at 1300℃ for 2 hours, 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 2.5, the gold grade of the gold-rich ferrous sulfide phase is approximately 38.8 g / t, the gold grade in the depleted slag is approximately 0.46 g / t, and the gold recovery rate is approximately 97.1%. Sulfur-containing flue gas is fed into a flue gas acid production system to prepare sulfuric acid.

[0040] (2) Hot-press oxidation of gold-rich ferrous sulfide phase: The gold-rich ferrous sulfide phase was finely ground to -74μm with a content of 90%, and the slurry mass concentration was adjusted to 10%. Hot-press oxidation was carried out under the conditions of hot-pressing temperature of 210℃, oxygen partial pressure of 0.4MPa, and holding time of 1.5 seconds to obtain oxidation slag and oxidation liquid. The sulfur oxidation rate was about 95%, and the gold grade of the oxidation slag was about 46.1g / t. The oxidation liquid was neutralized with lime to obtain neutralized liquid and gypsum slag. The gypsum slag was returned as a flux to participate in the oxidation smelting process.

[0041] (3) Gold extraction by cyanidation of oxide residue: After washing the oxide residue, water is added and lime is used to adjust the pH value to 11. Then it is sent to the gold extraction system, and the final gold leaching rate is about 98.1%.

[0042] (4) Liquid-solid separation: After liquid-solid separation of cyanide slurry, gold-loaded carbon and cyanide tailings are obtained. The cyanide tailings are sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0043] Example 3

[0044] This embodiment provides an efficient method for gold extraction from low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are: Fe 32.3%, S 33.4%, Cu 0.26%, SiO2 20.54%, Al2O3 3.48%, CaO 1.1%, Au 8.4g / t.

[0045] (1) Smelting of low-gold pyrite: The above-mentioned low-gold pyrite, along with 5% CaO and 5% coal powder by weight of the low-gold pyrite, are fed into a smelting furnace. Oxidative smelting is carried out at 1350℃ using oxygen-enriched gas with an oxygen concentration of 80%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the depleted slag is 1.3:1, the mass ratio of CaO to SiO2 is 0.3:1, and the Al2O3 content in the slag is approximately 5.3%. After the oxidative smelting is completed, the mixed melt is sent to the electric furnace depletion process. Under the depletion conditions of holding at 1300℃ for 2 hours and a coal powder ratio of 1% by weight of the mixed melt, 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 approximately 6, the gold grade of the gold-rich ferrous sulfide phase is approximately 74.6 g / t, the gold grade in the depleted slag is approximately 0.27 g / t, and the gold recovery rate is approximately 97.8%. Sulfur-containing flue gas is fed into a flue gas acid production system to prepare sulfuric acid.

[0046] (2) Hot-press oxidation of gold-rich ferrous sulfide phase: After the gold-rich ferrous sulfide phase is finely ground to a -74μm ratio of 60%, the slurry mass concentration is adjusted to 20%. Hot-press oxidation is carried out at a hot-pressing temperature of 210℃, an oxygen partial pressure of 0.8MPa, and a holding time of 1h to obtain oxidation slag and oxidation liquid. The sulfur oxidation rate is approximately 96%, and the gold content of the oxidation slag is approximately 87.3g / t. The oxidation liquid is neutralized with lime to obtain a neutralized liquid and gypsum slag. The gypsum slag is returned as a flux to participate in the oxidation smelting process.

[0047] (3) Oxidation residue cyanide gold extraction: After washing the oxidation residue, water is added and lime is used to adjust the pH value to 11. Then it is sent to the cyanide gold extraction system, and the final gold leaching rate is about 98.7%.

[0048] (4) Liquid-solid separation: After liquid-solid separation of cyanide slurry, gold-loaded carbon and cyanide tailings are obtained. The cyanide tailings are sent to the iron and steel smelting system, and the gold-loaded carbon is sent to the gold smelting system.

[0049] Example 4

[0050] This embodiment provides an efficient method for gold extraction from low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are: Fe 32.3%, S 33.4%, Cu 0.26%, SiO2 20.54%, Al2O3 3.48%, CaO 1.1%, Au 8.4g / t.

[0051] like Figure 1 As shown, the method includes the following steps:

[0052] (1) Smelting of low-gold pyrite: The above-mentioned low-gold pyrite, along with 4% CaO and 2% coal powder by weight of the low-gold pyrite, are fed into a smelting furnace. Oxidative smelting is carried out at 1350℃ with oxygen-enriched gas at an oxygen concentration of 80%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the depleted slag is 1:1, the mass ratio of CaO to SiO2 is 0.25:1, and the Al2O3 content in the slag is approximately 6.3%. After the oxidative smelting is completed, the mixed melt is sent to the electric furnace depletion process. Under the depletion conditions of holding at 1300℃ for 2 hours and a coal powder ratio of 3% by weight of the mixed melt, 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 approximately 2.5, the gold grade of the gold-rich ferrous sulfide phase is approximately 39 g / t, the gold grade in the depleted slag is approximately 0.23 g / t, and the gold recovery rate is approximately 98.5%. Sulfur-containing flue gas is fed into a flue gas acid production system to prepare sulfuric acid.

[0053] (2) Hot-press oxidation of gold-rich ferrous sulfide phase: After the gold-rich ferrous sulfide phase is finely ground to -74μm and accounts for 70%, the slurry mass concentration is adjusted to 20%. Hot-press oxidation is carried out under the conditions of hot-pressing temperature of 220℃, oxygen partial pressure of 0.5MPa, and holding time of 1.5 seconds to obtain oxidation slag and oxidation liquid. The sulfur oxidation rate is about 96.2%, and the gold grade of the oxidation slag is about 46.2g / t. The oxidation liquid is neutralized with lime to obtain neutralized liquid and gypsum slag. The gypsum slag is returned as a flux to participate in the oxidation smelting process.

[0054] (3) Oxidation residue cyanide gold extraction: After adding water to the oxidation residue, the pH value is adjusted to 11 with lime and then sent to the cyanide gold extraction system. Sodium cyanide and carbon are added to carry out cyanide gold extraction, and the final gold leaching rate is about 98.6%.

[0055] (4) Liquid-solid separation: After liquid-solid separation of cyanide slurry, gold leaching residue is sent to the iron and steel smelting system, and gold-loaded carbon is sent to the gold smelting system.

[0056] 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 highly efficient method for extracting gold from low-gold pyrite, characterized in that, Includes the following steps: Step 1: Oxidation smelting of low-gold pyrite: Low-gold pyrite, flux and reducing agent are fed into a smelting furnace for oxidation smelting. The resulting mixed melt is then depleted in an electric furnace to obtain gold-rich ferrous sulfide phase, depleted slag and sulfur-containing flue gas. The sulfur-containing flue gas is then fed into a flue gas sulfuric acid production system to prepare sulfuric acid. Step 2: Hot-press oxidation of the rich gold acid leaching residue: After being finely ground and slurried, the gold-rich ferrous sulfide phase is sent to a hot-press oxidation system for oxidation pretreatment to obtain oxidation slag and oxidation liquid. Step 3: Cyanide extraction of gold from oxide residue: After washing and slurry preparation, the oxide residue is sent to the cyanide gold extraction system to obtain gold-loaded carbon and cyanide tailings. The gold-loaded carbon is sent to the gold smelting system, and the cyanide tailings are sent to the iron and steel smelting system.

2. The method according to claim 1, characterized in that, In step 1, the flux is one or more of CaO, CaCO3, CaSO4, calcium borate, and quartz; the reducing agent is one or more of coke powder, coal powder, and biomass; and the amount of reducing agent used is 0-5% of the mass of the low-gold pyrite.

3. The method according to claim 1, characterized in that, In step 1, the 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 percentage of Al2O3 is less than 12%.

4. The method according to claim 1, characterized in that, In step 1, 0-3% of the mass of the mixed melt obtained by oxidative smelting is added to the mixed melt during the electric furnace depletion process. The reducing agent is one or more of coke powder, coal powder, biomass, natural gas, and biomass oil.

5. 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℃ for 1-2 hours.

6. The method according to claim 1, characterized in that, In step 2, the finely ground ferrous sulfide phase has a particle size of -74μm accounting for 50-90%, and the mass concentration of the slurry is 10-30%; the hot pressing oxidation temperature is 195-220℃, the oxygen partial pressure is 0.4-0.8MPa, and the reaction time is 1-3h.

7. The method according to claim 1, characterized in that, The oxidizing liquid obtained in step 2 is neutralized with lime to obtain a neutralized liquid and gypsum residue. The gypsum residue can be returned as a flux to participate in the oxidation smelting process.

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