Arsenic removal and leaching aid for gold stockpile

Abstract

This invention discloses a simultaneous arsenic removal aid for gold stockpiles, comprising a core arsenic removal aid component and functional auxiliary components. The core arsenic removal aid component is sodium cyanate. The functional auxiliary components are selected from at least one of sodium cyanate, sodium hydroxide, sodium chloride, barium chloride, ferric chloride, sulfamic acid, disodium hydrogen phosphate, trisodium citrate, ferrous sulfate, and sulfuric acid. Sodium cyanate and the functional auxiliary components work synergistically to simultaneously remove arsenic and aid leaching of arsenic-containing materials in gold stockpiles during the cyanide leaching process. The advantages are high efficiency in arsenic removal, low toxicity and safety, compatibility with cyanide leaching processes, and controllable cost.

Description

Technical Field

[0001] This invention relates to leaching aids, and more particularly to a simultaneous arsenic removal leaching aid for gold stockpiles. Background Technology

[0002] In the process of gold mining and smelting, arsenic-containing materials in gold stockpiles not only threaten production safety and the surrounding environment, but also significantly interfere with the efficiency of cyanide leaching. Simultaneous arsenic removal and efficient gold leaching have always been key technical challenges in gold mine processing.

[0003] Existing arsenic removal aids for gold stockpiles are mainly classified into the following categories: cyanide-based arsenic removal aids, oxide-based arsenic removal aids, and multi-component environmentally friendly arsenic removal aids. Among them, cyanide-based arsenic removal aids use sodium cyanide as the core arsenic removal aid component, combined with functional auxiliary components such as caustic soda, red phosphorus, and Leaching Gold No. 2. The dosage per ton of ore is 0.75kg-1.5kg of caustic soda, 5g-10g of red phosphorus, 0.6kg-1.2kg of sodium cyanide, and 0.25kg-0.5kg of Leaching Gold No. 2. This type of arsenic removal aid removes arsenic by forming soluble cyanide complexes with arsenic, and is suitable for gold ores containing stibnite, arsenopyrite, realgar, and orpiment, especially for roasted arsenic- and antimony-containing gold concentrates. However, sodium cyanide has an acute toxicity LD50 (rat, oral) of 6.4 mg / kg and is listed in the "List of Hazardous Chemicals". Its use generates cyanide-containing hazardous waste, requiring subsequent treatment through oxidative decomposition processes. Furthermore, excessive cyanide reacts with arsenic and sulfur to produce harmful byproducts. Oxidative arsenic removal aids use hydrogen peroxide as the core arsenic removal aid component, combined with functional auxiliary components such as ferrous sulfate and sulfuric acid. The dosage for the arsenic fixation stage is 0.5 g / L ferrous sulfate, 1 mL / L hydrogen peroxide, and 6.5 mL / L sulfuric acid. This type of arsenic removal aid converts arsenic into a fixable form through strong oxidation, making it suitable for the harmless treatment of gold mine cyanide slag and simultaneous arsenic removal. However, industrial-grade hydrogen peroxide costs 1500–2000 yuan / ton; it is prone to ineffective decomposition under pH < 3 or in the presence of metal ion catalysis, requiring low-temperature and light-protected storage during use, and it reacts ineffectively with cyanide. Multi-component environmentally friendly arsenic removal aids typically include sodium cyanate, sodium hydroxide, sodium chloride, barium chloride, ferric chloride, sulfamic acid, disodium hydrogen phosphate, and trisodium citrate. They work by using barium chloride and ferric chloride to decompose arsenic in the ore and promote the oxidation of harmful elements; sulfamic acid, disodium hydrogen phosphate, and trisodium citrate to remove sulfur components; and sodium chloride, sodium cyanate, and sodium hydroxide to synergistically promote gold dissolution. These multi-component environmentally friendly arsenic removal aids do not specify a core arsenic removal component, and their arsenic removal efficiency is 60%-75%, making them suitable for ores with an arsenic content of <0.5%.

[0004] Among existing arsenic removal aids for simultaneous leaching in gold yards, cyanide-based aids pose safety and environmental risks due to the high toxicity of sodium cyanide; hydrogen peroxide-based aids are costly, unstable, and have limited compatibility with gold leaching systems; and multi-component environmentally friendly arsenic removal aids have an arsenic removal efficiency of only 60%-75%. Therefore, existing arsenic removal aids for simultaneous leaching in gold yards cannot simultaneously meet the requirements of high-efficiency arsenic removal, low toxicity and safety, process compatibility, and cost control.

[0005] Melamine and its salts (such as sodium cyanide) are commonly used chemicals in the chemical industry. Their acute toxicity LD50 (rat, oral) is >5000 mg / kg, significantly lower than that of sodium cyanide. Currently, in the field of cyanide leaching in gold yards, there are no reports of using sodium cyanide as a core arsenic removal aid component in conjunction with functional auxiliary components. Research on its cyanide compatibility, arsenic removal selectivity, and synergistic leaching mechanism in cyanide leaching systems is lacking. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a gold yard simultaneous arsenic removal aid that is highly efficient, low in toxicity and safe, compatible with cyanide leaching gold process and cost-controllable.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a gold stockpile simultaneous arsenic removal leaching aid, comprising a core arsenic removal leaching aid component and a functional auxiliary component; the core arsenic removal leaching aid component is sodium cyanate; the functional auxiliary component is selected from at least one of sodium cyanate, sodium hydroxide, sodium chloride, barium chloride, ferric chloride, aminosulfonic acid, disodium hydrogen phosphate, trisodium citrate, ferrous sulfate, and sulfuric acid; the sodium cyanate and the functional auxiliary component work synergistically to simultaneously remove arsenic and aid leaching of arsenic-containing materials in the gold stockpile during the cyanide leaching process.

[0008] Compared with existing technologies, the advantages of this invention are as follows: by using sodium cyanide, which is low in toxicity and stable, to replace sodium cyanide as the core arsenic removal auxiliary component, the safety risks are significantly reduced. At the same time, sodium cyanide is well compatible with the cyanide leaching gold system. By using functional auxiliary components to enhance the reactivity of the core arsenic removal auxiliary component, promote the decomposition and transformation of arsenic, or adjust the pH of the leaching gold system, it can achieve efficient arsenic removal from different types of arsenic-containing materials. Moreover, all components used are commonly used industrial chemical raw materials, and the processing cost is controllable. Thus, it achieves a synergy of efficient arsenic removal, low toxicity and safety, process compatibility, and controllable cost.

[0009] Furthermore, the functional auxiliary components include ferric chloride and sodium hydroxide, which can enhance the decomposition reaction and fixation stability of arsenic, and are suitable for arsenic removal treatment of stibnite-containing gold ore.

[0010] Furthermore, the functional auxiliary components include ferrous sulfate and sulfuric acid, which optimize the fixation effect of sodium cyanate on soluble arsenates through ferrous salt precipitation and synergistic acid-base regulation, making it suitable for the harmless arsenic removal treatment of gold mine cyanide slag.

[0011] Furthermore, the functional auxiliary components include barium chloride, ferric chloride, aminosulfonic acid, disodium hydrogen phosphate, and trisodium citrate, which can simultaneously remove sulfur components from the ore, avoid the interference of sulfur on the arsenic removal process, and enhance the arsenic removal and leaching effect of sodium cyanurate on high-arsenic and high-sulfur materials.

[0012] Furthermore, the functional auxiliary components include sodium cyanate, sodium chloride, and sodium hydroxide. The synergistic effect of these three components can promote the dissolution of gold elements in the ore while removing arsenic, thereby increasing the gold leaching rate and achieving synergistic optimization of arsenic removal and gold extraction.

[0013] Furthermore, the mass ratio of sodium cyanurate to the functional auxiliary component is 1:5 to 5:1. This ratio range can be flexibly adjusted according to the actual working conditions such as the arsenic content of the arsenic-containing material and the type of ore to ensure the arsenic removal effect.

[0014] Furthermore, the mass ratio of sodium cyanurate to the functional auxiliary component is preferably 1:3 to 3:1, at which the arsenic removal efficiency and cost control are balanced.

[0015] Furthermore, after the leaching aid is used to treat arsenic-containing materials during the cyanide leaching process, the arsenic leaching concentration of the materials is not higher than 0.5 mg / L.

[0016] Furthermore, the purity of the sodium cyanurate is not less than 98%, and the content of the effective components of the functional auxiliary components is not less than 95%. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments.

[0018] Example 1: A gold stockpile synchronous arsenic removal leaching aid, comprising a core arsenic removal leaching aid component and functional auxiliary components. The core arsenic removal leaching aid component is 20 parts by weight of industrial-grade sodium cyanurate with a purity ≥98%. The functional auxiliary components include 10 parts by weight of ferric chloride and 5 parts by weight of sodium hydroxide.

[0019] The simultaneous arsenic removal aid of this embodiment was used to treat stibnite-type gold ore with medium arsenic content. The arsenic in the ore sample was mainly in the form of arsenopyrite, with an arsenic grade of 0.8%, a sulfur grade of 2.5%, a gold grade of 2.2 g / t, and 62% of the ore particles having a particle size ≤200 mesh. The simultaneous arsenic removal aid of this embodiment was mixed with sodium cyanide (industrial grade, purity ≥95%), and deionized water was added and stirred evenly to prepare a gold leaching solution with a total reagent mass concentration of 8% and a sodium cyanide mass concentration of 0.05%-0.1%. The gold leaching solution was then leached at a rate of 10-20 L / (h·m³). 2 The solution is sprayed onto the ore pile at a high intensity, with a leaching time of 24-36 hours, during which the pH of the reaction system is maintained at 9-10.

[0020] After leaching, the arsenic leaching concentration was measured to be 0.3 mg / L, the gold leaching rate was 87.4%, and the sodium cyanide consumption was 6.2 kg / t. The arsenic leaching concentration was determined according to the "Identification Standard for Hazardous Waste: Leaching Toxicity Identification" (GB5085.3-2007); the gold leaching rate was determined according to the "Gold Chemical Analysis Method" (GB / T7739.1-2019), and the calculation formula was: Gold leaching rate = (Total gold in the leachate / Total gold in the ore) × 100%; the sodium cyanide consumption was calculated by titrating the difference in sodium cyanide concentration in the solution before and after leaching. Furthermore, after storing the gold stockpile arsenic removal aid at room temperature for 3 months, the same ore sample was treated using the same process, and the arsenic removal aid effect did not show a significant decrease.

[0021] Example 2: A gold yard synchronous arsenic removal leaching aid, comprising a core arsenic removal leaching aid component and functional auxiliary components. The core arsenic removal leaching aid component is 30 parts by weight of industrial-grade sodium cyanurate with a purity ≥98%. The functional auxiliary components are 8 parts by weight of barium chloride, 6 parts by weight of ferric chloride, 4 parts by weight of aminosulfonic acid, 2 parts by weight of disodium hydrogen phosphate, and 2 parts by weight of trisodium citrate.

[0022] The simultaneous arsenic removal aid in this embodiment was used to treat high-arsenic and high-sulfur roasted gold concentrate. The main arsenic minerals in the ore sample were realgar and orpiment, with an arsenic grade of 1.5%, a sulfur grade of 3.8%, a gold grade of 2.8 g / t, and 70% of the ore particles having a particle size ≤200 mesh. The simultaneous arsenic removal aid was prepared into a gold leaching solution using the same method as in Example 1; then the gold leaching solution was leached at a rate of 10-20 L / (h·m³). 2 The leaching solution was sprayed onto the ore heap at an intensity of [insert concentration here], with a leaching time of 48-72 hours, during which the pH of the reaction system was maintained at 8-9. After leaching, the arsenic leaching concentration was measured to be 0.15 mg / L, the sulfur removal rate was 68.5%, the gold leaching rate was 90.7%, and the sodium cyanide consumption was 5.8 kg / t. The sulfur removal rate was determined according to the "Determination of Sulfur Content in Iron Ore" (GB / T6730.16-2016), and the calculation formula was: Sulfur removal rate = (Sulfur content before leaching - Sulfur content after leaching) / Sulfur content before leaching × 100%.

[0023] Example 3: A gold yard synchronous arsenic removal leaching aid, comprising a core arsenic removal leaching aid component and functional auxiliary components. The core arsenic removal leaching aid component is 25 parts by weight of industrial-grade sodium cyanurate with a purity ≥98%. The functional auxiliary components include 15 parts by weight of ferrous sulfate and 3 parts by weight of sulfuric acid.

[0024] This embodiment uses a simultaneous arsenic removal aid in gold stockpile leaching to treat gold ore cyanide tailings. The ore sample is gold ore cyanide tailings, with arsenic mainly existing in the form of soluble arsenate. The initial arsenic leaching concentration is 3.2 mg / L, and the gold grade is 1.5 g / t. The simultaneous arsenic removal aid is mixed with sodium cyanide to prepare a gold leaching solution. The total mass concentration of the simultaneous arsenic removal aid and sodium cyanide in the gold leaching solution is 0.8–1.5 wt%, and the mass concentration of sodium cyanide is 0.05–0.1 wt%. The gold leaching solution and cyanide tailings are mixed evenly at a liquid-to-solid ratio of 2–4 mL / g, and leaching is carried out with continuous stirring for 12–24 h. The natural pH of the system is 6.5–7.5. After treatment, the arsenic leaching concentration was measured to be 0.2 mg / L, the gold leaching rate was 81.6%, and the sodium cyanide consumption was 2.6 kg / t.

[0025] Example 4: The functional auxiliary component is composed of sodium cyanate, sodium chloride, and sodium hydroxide in a mass ratio of 2:1:1. Five groups of arsenic removal aids were prepared according to the mass ratios of sodium cyanate to the functional auxiliary component of 5:1, 2:1, 1:1, 1:3, and 1:5, respectively.

[0026] Five groups of arsenic removal aids were used to treat the same mineral samples as in Example 1. Each group of arsenic removal aids was mixed with sodium cyanide and then added to deionized water and stirred thoroughly to prepare a gold leaching solution with a total reagent concentration of 8% and a sodium cyanide concentration of 0.05%-0.1%. Column leaching was used for the experiment, with process parameters such as spray intensity and pH control remaining consistent with Example 1, and a leaching time of 24 hours. After leaching, various indicators were tested according to the same standard methods as in Example 1. When the mass ratio is 5:1, the arsenic leaching concentration is 0.45 mg / L, the gold leaching rate is 85%, and the sodium cyanide consumption is 6.1 kg / t, resulting in a relatively low reagent cost. When the mass ratio is 2:1, the arsenic leaching concentration is 0.32 mg / L, the gold leaching rate is 89.5%, and the sodium cyanide consumption is 5.8 kg / t, resulting in a moderate reagent cost. When the mass ratio is 1:1, the arsenic leaching concentration is 0.28 mg / L, and the gold leaching rate is 91.8%, resulting in a moderate reagent cost. When the mass ratio is 1:3, the arsenic leaching concentration is 0.25 mg / L, the gold leaching rate is 90.5%, and the sodium cyanide consumption is 5.6 kg / t, resulting in a relatively high reagent cost. When the mass ratio is 1:5, the arsenic leaching concentration is 0.23 mg / L, the gold leaching rate is 89.2%, and the sodium cyanide consumption is 5.9 kg / t, resulting in a high reagent cost.

[0027] Example 5: Three groups of gold leaching solutions were prepared. The first group consisted of sodium cyanide added to deionized water and stirred until homogeneous, resulting in a sodium cyanide concentration of 0.05%–0.1% by mass, without any leaching aids. The second group consisted of sodium cyanide mixed with 20 parts by mass of sodium tricyanate, then added to deionized water and stirred until homogeneous, resulting in a total reagent concentration of 8% and a sodium cyanide concentration of 0.05%–0.1% by mass, without any functional auxiliary components. The third group was prepared in the same manner as in Example 1. All three groups of gold leaching solutions were processed using the same process parameters as in Example 1, treating the same mineral samples as in Example 1. At the end of leaching, the gold leaching rate of the first group was 78.2%, and the arsenic leaching concentration was 1.8 mg / L; the gold leaching rate of the second group was 81.7%, and the arsenic leaching concentration was 0.85 mg / L; and the gold leaching rate of the third group was 87.4%, and the arsenic leaching concentration was 0.3 mg / L.

[0028] Comparative Example 1: 0.2 wt% sodium cyanide (excessive addition) and caustic soda were used to adjust the pH to 10-11. No other functional auxiliary components were added. The same leaching process as in Example 1 was used to treat the same mineral sample. After leaching, the arsenic leaching concentration was measured to be 0.4 mg / L, the gold leaching rate was 85.3%, and the sodium cyanide consumption was 12.0 kg / t. Compared with Example 1, the gold leaching rate in this comparative example was lower, and the sodium cyanide consumption was 2.1 times that of Example 1.

[0029] Comparative Example 2: A gold leaching solution with a total reagent concentration of 8% (8 wt%) and sodium cyanide (0.05%-0.1 wt%) was prepared by mixing 3 wt% hydrogen peroxide, ferrous sulfate, sulfuric acid, and sodium cyanide, and then adding deionized water and stirring until homogeneous. The same leaching process as in Example 1 was used to treat the same mineral sample. After leaching, the arsenic leaching concentration was measured to be 0.35 mg / L, the gold leaching rate was 86.8%, and the sodium cyanide consumption was 6.8 kg / t. Compared with Example 1, this comparative example showed a lower gold leaching rate, higher sodium cyanide consumption, and higher overall reagent cost.

[0030] Comparative Example 3: Using only sodium cyanide, without any functional auxiliary components, a gold leaching solution was prepared with sodium cyanide, resulting in a total reagent concentration of 8% and a sodium cyanide concentration of 0.05-0.1 wt%. The same leaching process as in Example 1 was used to treat the same mineral sample. After leaching, the arsenic leaching concentration was measured to be 0.85 mg / L, the gold leaching rate was 81.7%, and the sodium cyanide consumption was 7.9 kg / t. Compared to Example 1, the arsenic leaching concentration in this comparative example exceeded the control target of 0.5 mg / L.

[0031] As can be seen from the above examples and comparative examples, using sodium cyanide as the core arsenic removal aid component, combined with multiple functional auxiliary components such as ferric chloride and sodium hydroxide, ferrous sulfate and sulfuric acid, or barium chloride, ferric chloride, aminosulfonic acid, disodium hydrogen phosphate, and trisodium citrate, the resulting simultaneous arsenic removal aid can be applied to the gold stockpile treatment process of various arsenic-containing materials such as medium-arsenic stibnite-type gold ore, high-arsenic and high-sulfur roasted gold concentrate, and gold ore cyanide slag. It significantly improves the gold leaching rate, significantly reduces sodium cyanide consumption, and lowers reagent costs, and has broad application prospects in the industrial production of gold stockpiles.

Claims

1. A gold yard simultaneous arsenic removal leaching aid, comprising a core arsenic removal leaching aid component and functional auxiliary components; characterized in that, The core arsenic removal aid component is sodium cyanate; the functional auxiliary component is selected from at least one of sodium cyanate, sodium hydroxide, sodium chloride, barium chloride, ferric chloride, aminosulfonic acid, disodium hydrogen phosphate, trisodium citrate, ferrous sulfate, and sulfuric acid; the sodium cyanate and the functional auxiliary component work synergistically to simultaneously remove arsenic and aid leaching of arsenic-containing materials in the gold storage yard during the cyanide leaching process.

2. The gold yard simultaneous arsenic removal aid according to claim 1, characterized in that, The functional auxiliary components include ferric chloride and sodium hydroxide.

3. The gold yard simultaneous arsenic removal aid according to claim 1, characterized in that, The functional auxiliary components include ferrous sulfate and sulfuric acid.

4. The gold heap leach synchronization arsenic removal lixivium of claim 1 wherein, The functional auxiliary components include barium chloride, ferric chloride, aminosulfonic acid, disodium hydrogen phosphate, and trisodium citrate.

5. The gold yard simultaneous arsenic removal aid according to claim 1, characterized in that, The functional auxiliary components include sodium cyanate, sodium chloride, and sodium hydroxide.

6. The gold yard simultaneous arsenic removal aid according to claim 1, characterized in that, The mass ratio of sodium cyanurate to the functional auxiliary component is 1:5 to 5:

1.

7. The gold yard simultaneous arsenic removal aid according to claim 6, characterized in that, The mass ratio of sodium cyanurate to the functional auxiliary component is 1:3 to 3:

1.

8. The gold yard simultaneous arsenic removal aid according to any one of claims 1 to 7, characterized in that, After the leaching aid is used to treat arsenic-containing materials during the cyanide leaching process, the arsenic leaching concentration of the materials is not higher than 0.5 mg / L.

9. The gold yard simultaneous arsenic removal aid according to any one of claims 1 to 8, characterized in that, The purity of the sodium cyanurate is not less than 98%, and the content of the effective components of the functional auxiliary components is not less than 95%.