Method for improving leaching rate of refractory gold

Abstract

The application discloses a method for improving leaching rate of refractory gold, and belongs to the technical field of hydrometallurgy. The method comprises the following steps: adding sodium persulfate, sodium percarbonate and ferrous chloride into the ore pulp during alkali pretreatment; introducing a gold leaching agent, adjusting the pH of the ore pulp to 9-12, leaching gold, and completing the leaching of the refractory gold; the adding concentration of the sodium persulfate is 0.01-1 mol / L, the adding concentration of the sodium percarbonate is 0.01-0.5 mol / L, and the adding amount of the ferrous chloride is 50% of the adding amount of the sodium persulfate. The method can generate high-activity free radicals under the alkaline condition through the sodium persulfate and the sodium percarbonate, can deeply oxidize and damage the ore inclusion structure, and can significantly improve the leaching efficiency of the gold. Meanwhile, the sodium carbonate generated by the sodium percarbonate can stabilize the alkaline environment of the solution, can improve the flowability of the ore pulp, and can improve the contact efficiency of the oxidant and the mineral particles, thereby improving the leaching efficiency of the gold.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a method for improving the leaching rate of refractory gold. Background Technology

[0002] With the gradual depletion of easily processed gold ore resources, difficult-to-process, refractory gold ores have become an important research focus in the field of gold extraction. In these ores, gold is often encased in sulfide minerals such as pyrite (FeS) and arsenopyrite (FeAsS), making it difficult for traditional cyanide leaching processes to effectively recover gold. Therefore, pretreatment of the ore is necessary to disrupt the sulfide structure, release the encased gold, and improve its leachingability.

[0003] Currently, common pretreatment methods for ores include roasting oxidation and pressure oxidation. Roasting oxidation processes the ore at high temperatures, oxidizing sulfides into oxides; however, this method is energy-intensive and may produce harmful gases, causing environmental pollution. Pressure oxidation is carried out under high temperature and pressure conditions, requiring sophisticated equipment and incurring high investment costs; furthermore, existing pretreatment methods have limited effectiveness in improving gold leaching rates. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems in the prior art and provide a method to improve the leaching rate of refractory gold, which achieves deep oxidation and destruction of the ore inclusion structure under relatively mild conditions, thereby significantly improving the gold leaching efficiency.

[0005] The present invention discloses a method for improving the leaching rate of refractory gold, comprising the following steps: adding sodium persulfate, sodium percarbonate and ferrous chloride to the ore slurry after alkali pretreatment to form a dual Fenton-like system and performing pretreatment; after the pretreatment is completed, introducing a gold leaching agent and adjusting the pH of the ore slurry to the range of 9-12, and leaching gold to complete the leaching of refractory gold.

[0006] The concentration of sodium persulfate is 0.01 mol / L to 1 mol / L, the concentration of sodium percarbonate is 0.01 mol / L to 0.5 mol / L, and the amount of ferrous chloride added is 50% of the amount of sodium persulfate added.

[0007] This invention adds sodium persulfate, sodium percarbonate, and ferrous chloride to the alkali pretreated slurry to form a dual Fenton-like system, which works synergistically with the alkaline environment to perform deep oxidation pretreatment on encapsulated gold ore, thereby improving the leaching of gold.

[0008] Preferably, the alkali-pretreated slurry is obtained by grinding the gold ore raw material to a particle size of -74μm or more (90%), adding water and stirring to obtain a slurry with a mass concentration of 10% to 40%, and then pretreating it with alkali. The gold ore raw material is ground to a particle size of -74μm (90%) and prepared into a slurry with a mass concentration of 10% to 40% to ensure optimal reaction kinetic conditions.

[0009] Preferably, the alkali added during the alkali pretreatment of the slurry is any one of sodium hydroxide, calcium oxide, or calcium hydroxide. In the alkali pretreatment stage of the slurry, selecting sodium hydroxide, calcium oxide, or calcium hydroxide as the alkalinity regulator not only achieves a rapid increase in pH but also significantly optimizes mineral surface activation, oxidant efficiency, and process economy through its unique physicochemical properties and synergistic effect with the subsequent oxidation system.

[0010] Preferably, stirring is required during both the pretreatment and leaching processes.

[0011] Preferably, during both the pretreatment and leaching stages, stirring is performed at a temperature of 10℃ to 90℃ for 4 hours to 24 hours, with the stirring rate controlled at 80 r / min to 500 r / min. This invention enhances reaction kinetics by controlling multiple parameters—temperature, stirring time, and stirring rate—during the pretreatment and leaching stages.

[0012] Preferably, the slurry environment during both the pretreatment and leaching processes is an oxygen or air atmosphere.

[0013] Preferably, the gold leaching agent is a cyanide-containing leaching agent or sodium thiosulfate of the copper amine system, and the concentration of the gold leaching agent is 0.01 mol / L to 1 mol / L.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] This invention utilizes the synergistic effect of sodium persulfate and sodium percarbonate to generate highly reactive free radicals (such as sulfate and hydroxyl radicals) under alkaline conditions. These free radicals deeply oxidize and destroy the inclusion structure in the ore, significantly improving gold leaching efficiency. Simultaneously, sodium percarbonate, as a composite oxidant, not only releases hydrogen peroxide (H₂O₂) for the Fenton reaction, but the ferrous ions generated by ferrous chloride catalyze sodium persulfate to produce more free radicals, forming a dual Fenton-like system. Furthermore, the generated sodium carbonate (Na₂CO₃) stabilizes the alkaline environment of the solution, providing crucial conditions for the synergistic effect of hydroxide ions and sodium persulfate. In addition, sodium carbonate has a dispersing effect in the slurry, effectively preventing mineral particle agglomeration, thereby improving slurry flowability and the contact efficiency between the oxidant and mineral particles, thus increasing gold leaching efficiency. Compared with traditional alkali pretreatment and hydrogen peroxide oxidation methods, for the same ore sample, the method of this invention has stronger oxidation capacity, with a gold leaching rate reaching up to 90.18%, a significant improvement over traditional alkali and hydrogen peroxide pretreatment methods.

[0016] The method described in this invention offers mild conditions and stable processes. Highly efficient pre-oxidation and gold leaching can be achieved under relatively mild operating conditions (e.g., pH 9-12, temperature 10℃-90℃). Compared to the high temperature and high pressure conditions required by traditional methods, the mild operation of this invention reduces energy consumption, extends equipment lifespan, and lowers maintenance and replacement costs. The stability of these operating conditions also makes the industrial application of the process more feasible. Furthermore, compared to roasting oxidation and pressurized oxidation methods, the method of this invention does not produce harmful gases such as sulfur dioxide, significantly improving environmental friendliness.

[0017] The pretreatment process of this invention is not only applicable to the treatment of high-arsenic gold ores, but also has broad application prospects. It is also suitable for other refractory gold ores encapsulated by inert minerals such as quartz, demonstrating superior oxidation capacity and gold leaching effect. Its strong adaptability to different ore types makes this technology extremely promising for application in the mining industry, capable of meeting diverse ore processing needs. Attached Figure Description

[0018] Figure 1 This is a comparison chart of the gold leaching rates of various comparative examples and embodiments of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; when the absolute position of the described objects changes, the relative positional relationship may also change accordingly.

[0021] This embodiment provides a method for improving the leaching rate of refractory gold ores, the steps of which are as follows:

[0022] In this embodiment, sodium persulfate, sodium percarbonate, and ferrous chloride are added to the ore slurry after alkali treatment to form a dual Fenton-like system. This system works synergistically with the alkali environment to perform deep oxidation pretreatment on the encapsulated gold ore to improve the leaching of gold. After the pretreatment is completed, a gold leaching agent is introduced, and the pH of the ore slurry is adjusted to the range of 9-12 for leaching, thus completing the leaching of difficult-to-leach gold.

[0023] Under alkaline conditions, sodium percarbonate and sodium persulfate act as oxidants, forming a Fenton-like system with iron ions to generate highly oxidizing free radicals, such as hydroxyl radicals and sulfate radicals, which can effectively oxidize sulfides. The reaction equations are as follows:

[0024] Fe 2+ +Na₂S₂O₈→Fe 3+ +2Na + +2SO4 2− ;

[0025] Fe 2+ +Na₂CO₃⋅1.5H₂O₂→Fe 3+ +Na₂CO₃ + 1.5⋅OH - ;

[0026] This embodiment, by constructing a dual Fenton-like system and utilizing the synergistic effect of an alkaline environment, not only significantly improves oxidation capacity but also optimizes slurry flowability through the dispersing effect of sodium carbonate, thereby significantly enhancing the pretreatment effect on different types of refractory gold ores (including refractory gold ores and gold ores encased in quartz). Simultaneously, sodium percarbonate, as a composite oxidant, not only releases hydrogen peroxide (H₂O₂) for the Fenton-like reaction, but the sodium carbonate (Na₂CO₃) it generates also stabilizes the alkaline environment of the solution, providing crucial conditions for the synergistic effect of hydroxide ions and sodium persulfate. Furthermore, sodium carbonate has a dispersing effect in the slurry, effectively preventing mineral particle agglomeration, thereby improving slurry flowability and the contact efficiency between the oxidant and mineral particles.

[0027] This embodiment utilizes the synergistic effect of sodium persulfate and sodium percarbonate to generate highly reactive free radicals (such as sulfate radicals and hydroxyl radicals) under alkaline conditions, thereby deeply oxidizing and destroying the ore inclusion structure. Compared with traditional alkaline pretreatment or hydrogen peroxide oxidation methods, this embodiment's process has stronger oxidation capabilities and a higher gold leaching rate for the same ore sample.

[0028] In this embodiment, the concentration of sodium persulfate is 0.01 mol / L to 1 mol / L, the concentration of sodium percarbonate is 0.01 mol / L to 0.5 mol / L, and the amount of ferrous chloride added is 50% of the amount of sodium persulfate added; all three are industrial grade or analytical grade.

[0029] As a preferred embodiment, the alkali-pretreated slurry is obtained by grinding gold ore raw materials to a particle size of -74μm or more (90%), adding water and stirring to obtain a slurry with a mass concentration of 10% to 40%, and then pretreating with alkali to ensure optimal reaction kinetic conditions. Here, -74μm or more means that the proportion of particles with a maximum particle size not exceeding 74μm is more than 90%.

[0030] In a preferred embodiment, the alkali added during the alkali pretreatment of the slurry is any one of sodium hydroxide, calcium oxide, or calcium hydroxide.

[0031] In a more preferred embodiment, stirring is required during both the pretreatment and leaching processes. During both the pretreatment and leaching processes, stirring is carried out at a temperature of 10°C to 90°C for 4 to 24 hours, and the stirring rate is controlled at 80 r / min to 500 r / min.

[0032] In a more preferred embodiment, the slurry environment during both the pretreatment and leaching processes is an oxygen or air atmosphere.

[0033] As a more preferred embodiment, the pretreatment is carried out in an air atmosphere, the pretreatment temperature is 10℃~40℃, the pretreatment time is 4h~12h, and the stirring rate is controlled at 80r / min~500r / min.

[0034] As a more preferred embodiment, the immersion is carried out in an air atmosphere, the immersion temperature is 10℃~40℃, the immersion time is 4h~12h, and the stirring rate is controlled at 80r / min~500r / min.

[0035] In a preferred embodiment, the gold leaching agent is at least one of sodium thiosulfate in a copper-amine system, a cyanide-containing leaching agent, or other compounded gold leaching agents, and the concentration of the gold leaching agent is 0.01 mol / L to 1 mol / L. After introducing the gold leaching agent, sodium hydroxide is used to adjust the pH of the slurry to 9 to 12.

[0036] To facilitate understanding of the present invention, a more comprehensive and detailed description will be given below in conjunction with the embodiments, but the present invention is not limited to the following embodiments.

[0037] The refractory gold ore in this embodiment includes:

[0038] (1) No. 1 Carlin-type refractory gold deposit with high arsenic and high sulfur content, gold grade 32.78 g / t, sulfur content 24%, and arsenic content 28%.

[0039] (2) Sulfur- and arsenic-containing quartz-encapsulated refractory gold deposit, with a gold grade of 5.88 g / t, a sulfur content of 4.3%, and an arsenic content of 1.21%.

[0040] Compare with Example 1

[0041] The high-arsenic, high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 55.31%.

[0042] Compare with Example 2

[0043] The high-arsenic, high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 69.68%.

[0044] Compare with Example 3

[0045] (1) High-arsenic, high-sulfur Carlin-type refractory gold ore was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.01 mol / L sodium percarbonate. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 71.46%.

[0046] Compare with Example 4

[0047] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 72.81%.

[0048] Compare with Example 5

[0049] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 80.06%.

[0050] Compare with Example 6

[0051] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.01 mol / L sodium percarbonate. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 83.28%.

[0052] Example 1

[0053] The high-arsenic, high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed with 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate and 0.01 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 85.31%.

[0054] Example 2

[0055] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -18 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate and 0.01 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, with a stirring rate of 450 r / min and a slurry temperature of 25 °C. The pH of the slurry was adjusted to 11 with sodium hydroxide. The leaching result was a gold leaching rate of 90.18%.

[0056] Compared with Control Examples 1, 2, 3, 4, 5, and 6, Examples 1 and 2 showed significantly improved leaching rates. The experimental results are shown in [Figure 1]. Figure 1 As shown.

[0057] Example 3

[0058] The high-arsenic, high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -50 μm (95%), and the slurry concentration was adjusted to 15%. Alkali pretreatment was performed by adding 0.03 mol / L calcium hydroxide, followed by the introduction of 0.01 mol / L sodium persulfate and 0.03 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 10 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h, the stirring rate was 450 r / min, the slurry temperature was 10 °C, and the pH of the slurry was adjusted to 12 with calcium hydroxide. Gold leaching was then performed until the refractory gold was completely leached.

[0059] Example 4

[0060] The high-arsenic, high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -70 μm (95%), and the slurry concentration was adjusted to 10%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.08 mol / L sodium persulfate and 0.01 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 12 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 12 h, the stirring rate was 450 r / min, the slurry temperature was 25 °C, and the pH of the slurry was adjusted to 10 with calcium oxide. Gold leaching was then performed until the refractory gold was completely leached.

[0061] Example 5

[0062] The high-arsenic and high-sulfur Carlin-type refractory gold ore (1) was ground to a particle size of -74 μm (95%), and the pulp concentration was adjusted to 20%. 0.03 mol / L calcium oxide was added for alkali pretreatment, followed by the introduction of 1 mol / L sodium persulfate and 0.01 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 80 r / min, and the pulp temperature was 90 °C. After filtering and washing the slag, sodium thiosulfate (a copper-amine system) was added as the gold leaching agent at a dosage of 15 kg / t. The treatment time was 24 h, the stirring rate was 80 r / min, the pulp temperature was 90 °C, and the pulp pH was adjusted to 9 with calcium oxide. Gold leaching was then carried out until the refractory gold was completely leached.

[0063] Example 6

[0064] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -30 μm (95%), and the slurry concentration was adjusted to 45%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate and 0.5 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 4 hours, the stirring rate was 450 r / min, and the slurry temperature was 40℃. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 4 hours, the stirring rate was 450 r / min, the slurry temperature was 400℃, and the pH of the slurry was adjusted to 11 with sodium hydroxide. Gold leaching was then performed until the refractory gold was completely leached.

[0065] Example 7

[0066] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -40 μm (95%), and the slurry concentration was adjusted to 25%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.06 mol / L sodium persulfate and 0.4 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 500 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h. The stirring rate was 500 r / min, the slurry temperature was 25 °C, and the pH of the slurry was adjusted to 10 with sodium hydroxide. Gold leaching was then performed until the refractory gold was completely leached.

[0067] Example 8

[0068] The (2) type refractory gold ore containing sulfur and arsenic, encapsulated in quartz, was ground to a particle size of -20 μm (95%), and the slurry concentration was adjusted to 35%. Alkali pretreatment was performed by adding 0.03 mol / L sodium hydroxide, followed by the introduction of 0.03 mol / L sodium persulfate and 0.1 mol / L sodium percarbonate. The amount of ferrous chloride added was 50% of the amount of sodium persulfate added. The treatment time was 24 h, the stirring rate was 450 r / min, and the slurry temperature was 25 °C. After filtering and washing the slag, a cyanide-containing gold leaching agent was added at a dosage of 15 kg / t for 24 h. The stirring rate was 450 r / min, the slurry temperature was 25 °C, and the pH of the slurry was adjusted to 11 with sodium hydroxide. Gold leaching was then performed until the refractory gold was completely leached.

[0069] The gold leaching rates in Examples 3 to 5 were all above 84%, and the gold leaching rates in Examples 6 to 8 were all above 87%.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the leaching rate of refractory gold, characterized in that, Includes the following steps: Sodium persulfate, sodium percarbonate, and ferrous chloride were added to the slurry after alkali pretreatment to form a dual Fenton-like system, and then pretreated. After pretreatment, a gold leaching agent is introduced, and the pH of the slurry is adjusted to the range of 9-12 for leaching to complete the leaching of difficult-to-leach gold. The slurry after alkali pretreatment is obtained by grinding the gold ore raw material to a particle size of -74μm or more (more than 90%), adding water and stirring to obtain a slurry with a mass concentration of 10%-40%, and then pretreating it with alkali. The concentration of sodium persulfate is 0.01 mol / L to 1 mol / L, the concentration of sodium percarbonate is 0.01 mol / L to 0.5 mol / L, and the amount of ferrous chloride added is 50% of the amount of sodium persulfate added.

2. The method for improving the leaching rate of refractory gold as described in claim 1, characterized in that, The alkali added during the alkali pretreatment of the slurry is any one of sodium hydroxide, calcium oxide, or calcium hydroxide.

3. The method for improving the leaching rate of refractory gold as described in claim 1, characterized in that, Both the pretreatment and leaching processes require stirring.

4. The method for improving the leaching rate of refractory gold as described in claim 1, characterized in that, Both the pretreatment and leaching processes were carried out at a temperature of 10℃ to 90℃ for 4h to 24h, with the stirring rate controlled at 80r / min to 500r / min.

5. The method for improving the leaching rate of refractory gold as described in claim 1, characterized in that, The slurry environment during both the pretreatment and leaching processes is an oxygen or air atmosphere.

6. The method for improving the leaching rate of refractory gold as described in claim 1, characterized in that, The gold leaching agent is a cyanide-containing leaching agent, and the concentration of the gold leaching agent is 0.01 mol / L to 1 mol / L.

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