High-grade gold concentrate wet deimpurification metallurgical process

Abstract

A high-grade gold concentrate wet impurity removal metallurgical process is used for removing Pb, Fe, S and Cu in the gold concentrate; the wet impurity removal metallurgical process comprises the following steps: S1: sulfuric acid roasting; S2: sodium carbonate alkali leaching; S3: acetic acid leaching; and S4: gold smelting and ingot casting. The wet impurity removal metallurgical process has a better treatment effect on the oxides such as oxidized iron and oxidized lead contained in the gold concentrate, and no secondary impurities are generated in the impurity removal process. After the impurity removal, the gold ingot with a fineness of more than 95% can be obtained. The wet impurity removal metallurgical process has low energy consumption, small labor intensity, good operation environment, low corrosion requirement, and is a new impurity removal metallurgical process combining pyrometallurgy and hydrometallurgy.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a wet metallurgical process for removing impurities from high-grade gold concentrate. Background Technology

[0002] Traditional impurity removal and smelting processes mainly include pyrometallurgical refining and hydrometallurgical refining.

[0003] Pyrometallurgical processes generally include smelting, water crushing, acid leaching, and ingot casting. Smelting involves adding various solvents to a crucible or induction furnace to separate the alloy from the slag. The alloy is then melted again in the furnace and water crushed to break it into small, bead-like fragments, facilitating the subsequent acid leaching process. After acid leaching, ingots are cast. The disadvantages of pyrometallurgical processes include high labor intensity, high energy consumption, and a poor working environment.

[0004] Hydrometallurgical processes include nitric acid purification and hydrochloric acid purification.

[0005] Nitric acid is a strong oxidizing and corrosive acid. When used to remove impurities from concentrates, impurities such as Ag, Cu, pyrite, galena, and pyrrhotite react with the nitric acid and enter the liquid phase, while gold remains in the solid phase. After solid-liquid separation, the gold is separated from most of the impurities. However, nitric acid is not very effective at removing oxides such as iron oxide and lead oxide. Furthermore, the impurity removal process generates a significant amount of nitrogen oxides, which has a substantial environmental impact and results in high subsequent disposal costs.

[0006] Hydrochloric acid is an aqueous solution of hydrogen chloride. It is a strong monoprotic acid that can react with many metals and metal compounds to form soluble metal chlorides. However, the disadvantages of using hydrochloric acid for impurity removal are: it is more expensive than sulfuric acid, has a lower boiling point, is volatile, requires poorer working conditions, and necessitates higher equipment corrosion resistance. Summary of the Invention

[0007] This invention addresses the current production status of the concentrate purification and impurity removal process in a certain concentrator plant, proposing a purification and impurity removal process for high-grade gold concentrate to solve the problems of poor production environment and high energy consumption in pyrometallurgical processes, as well as the problems in hydrometallurgical processes.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A hydrometallurgical process for removing impurities from high-grade gold concentrate, comprising the following steps:

[0010] S1: Sulfuric acid roasting

[0011] Gold concentrate was mixed with 98% concentrated sulfuric acid at a ratio of 1 kg gold concentrate to 0.75 L concentrated sulfuric acid, and roasted at 550-630 °C. The following reaction occurred, and Fe, S, and Cu in the gold concentrate were then removed by dissolving in water: Pb + 2H₂SO₄ = PbSO₄↓ + 2H₂O + SO₂↑

[0012] 2Fe + 6H2SO4= Fe2(SO4)3 + 6H2O + 3SO2↑

[0013] Cu + 2H2SO4= CuSO4 + 2H2O + SO2↑

[0014] S + 2H₂SO₄ = 2H₂O + 3SO₂↑

[0015] S2: Sodium carbonate alkali leaching

[0016] When gold concentrate mixed with lead sulfate is leached in a sodium carbonate solution, the following reaction occurs:

[0017] PbSO4+ Na2CO3= PbCO3↓+ Na2SO4

[0018] S3: Acetic acid leaching

[0019] When gold concentrate containing lead carbonate is leached in acetic acid, the following reaction occurs, producing water-soluble lead acetate. The lead acetate is then removed by filtration:

[0020] PbCO3+2CH3COOH = Pb(CH3COO)2 + H2O + CO2↑

[0021] S4: Gold Ingot Casting

[0022] The obtained sponge gold is cast into ingots.

[0023] To further improve the technical solution, in S2, the sodium carbonate solution is a saturated solution, and the weight ratio of gold concentrate to sodium carbonate solution is 1:0.35.

[0024] To further improve the technical solution, the temperature of the sodium carbonate solution was set at 70°C.

[0025] To further improve the technical solution, in S3, the weight ratio of gold concentrate to acetic acid is 1:0.75.

[0026] To further improve the technical solution, the temperature of the acetic acid was set at 70℃.

[0027] To further improve the technical solution, borax was added to the sponge gold before casting the ingot, with the weight ratio of sponge gold to borax being 1:0.3.

[0028] After implementing the above technical solution, the beneficial effects of this invention compared to the prior art are as follows:

[0029] This wet impurity removal metallurgical process is highly effective in treating oxides such as iron oxide and lead oxide in gold concentrate, and it does not generate secondary impurities during the process. After impurity removal, gold ingots with a purity of over 95% can be obtained.

[0030] This hydrometallurgical process for removing impurities has low energy consumption, low labor intensity, good working environment, and low corrosion requirements. It is a new impurity removal metallurgical process that combines pyrometallurgical refining and hydrometallurgical processes. Detailed Implementation

[0031] Those skilled in the art should understand that these embodiments are merely for explaining the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0032] A hydrometallurgical process for removing impurities from high-grade gold concentrate is disclosed. In this embodiment, the main impurity elements and their contents in a high-grade gold concentrate from a certain concentrator are: Au: 18%, Pb: 55%, Fe: 10%, S: 15%, Cu: 1%.

[0033] To overcome the drawbacks of pyrometallurgical and hydrometallurgical processes, a high-grade gold concentrate hydrometallurgical process for impurity removal was adopted, which includes the following steps:

[0034] S1: Sulfuric acid roasting

[0035] The gold concentrate was mixed with 98% concentrated sulfuric acid and then roasted.

[0036] Specifically, the mixing ratio of gold concentrate to concentrated sulfuric acid is 1 kg gold concentrate : 0.75 L concentrated sulfuric acid. The roasting temperature is 550-630℃.

[0037] During roasting, the following reaction occurs:

[0038] Pb + 2H2SO4= PbSO4↓+ 2H20 + SO2↑

[0039] 2Fe + 6H2SO4= Fe2(SO4)3 + 6H2O + 3SO2↑

[0040] Cu + 2H2SO4= CuSO4 + 2H2O + SO2↑

[0041] S + 2H₂SO₄ = 2H₂O + 3SO₂↑

[0042] As can be seen from the above reactions, gold does not react with concentrated sulfuric acid. Iron and copper in the gold concentrate react with concentrated sulfuric acid to form water-soluble sulfates, which are then removed. Sulfur reacts with concentrated sulfuric acid to produce sulfur dioxide gas, which is also removed. Lead reacts with concentrated sulfuric acid to form water-insoluble lead sulfate precipitate, and the lead remains in the gold concentrate in the form of lead sulfate.

[0043] S2: Sodium carbonate alkali leaching

[0044] Gold concentrate mixed with lead sulfate is leached in a sodium carbonate solution.

[0045] Specifically, the sodium carbonate solution is a saturated sodium carbonate solution at 70°C, and the weight ratio of gold concentrate to sodium carbonate solution is 1:0.35. The saturated sodium carbonate solution at 70°C facilitates the reaction.

[0046] During alkaline leaching, the following reaction occurs:

[0047] PbSO4+ Na2CO3= PbCO3↓+ Na2SO4

[0048] As can be seen from the above reactions, gold does not react with sodium carbonate solution, while lead sulfate reacts with sodium carbonate solution to form lead carbonate precipitate, and lead remains in the gold concentrate in the form of lead carbonate.

[0049] S3: Acetic acid leaching

[0050] The gold concentrate mixed with lead carbonate was leached in acetic acid.

[0051] Specifically, the weight ratio of gold concentrate to acetic acid is 1:0.75. The acetic acid is reacted at 70°C; increasing the temperature helps to increase the reaction rate and the solubility of lead acetate.

[0052] During acid leaching, the following reaction occurs:

[0053] PbCO3+2CH3COOH = Pb(CH3COO)2 + H2O + CO2↑

[0054] As can be seen from the above reactions, gold does not react with acetic acid, while lead carbonate reacts with acetic acid to produce lead acetate, which is soluble in water.

[0055] After filtration, lead acetate can be removed. After drying, sponge gold can be obtained.

[0056] S4: Gold Ingot Casting

[0057] The obtained sponge gold is then cast into ingots. Specifically, borax is added to the sponge gold before casting, with a weight ratio of sponge gold to borax of 1:0.3.

[0058] After melting and casting, gold ingots with a purity of over 95% can be obtained.

[0059] As described above, this hydrometallurgical process for removing impurities has a superior effect on treating oxides such as iron oxide and lead oxide in gold concentrate. It does not generate other secondary impurities during the removal process and can yield gold ingots with a purity of over 95%. This hydrometallurgical process features low energy consumption, low labor intensity, a good working environment, and low corrosion requirements. It is a novel impurity removal metallurgical process combining pyrometallurgical and hydrometallurgical methods.

[0060] The parts not detailed herein are prior art. 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 variations 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 high-grade gold concentrate wet-removing impurity metallurgical process for removing Pb, Fe, S, Cu in the gold concentrate, the main impurity elements in the gold concentrate and their contents are Pb: 55%, Fe: 10%, S: 15%, Cu: 1%, characterized in that: The aforementioned hydrometallurgical process for removing impurities from gold concentrate includes the following steps: S1: Mix gold concentrate with 98% concentrated sulfuric acid at a ratio of 1 kg gold concentrate to 0.75 L concentrated sulfuric acid, roast at 550-630 °C, and the following reaction occurs. Then, remove Fe, S, and Cu from the gold concentrate by dissolving it in water: Pb + 2H2SO4= PbSO4↓+ 2H2O + SO2↑ 2Fe + 6H2SO4= Fe2(SO4)3 + 6H2O + 3SO2↑ Cu + 2H2SO4= CuSO4 + 2H2O + SO2↑ S + 2H₂SO₄ = 2H₂O + 3SO₂↑ S2: When gold concentrate mixed with lead sulfate is placed in a sodium carbonate solution for alkaline leaching, the following reaction occurs: PbSO4+ Na2CO3= PbCO3↓+ Na2SO4 S3: Gold concentrate mixed with lead carbonate is leached in acetic acid, and the following reaction occurs, producing water-soluble lead acetate. The lead acetate is removed by filtration: PbCO3+2CH3COOH = Pb(CH3COO)2 + H2O + CO2↑ S4: Gold Ingot Casting The obtained sponge gold is cast into ingots.

2. The wet metallurgical process for removing impurities from high-grade gold concentrate as described in claim 1, characterized in that: in S2, the sodium carbonate solution is a saturated solution, and the weight ratio of gold concentrate to sodium carbonate solution is 1:0.

35.

3. The hydrometallurgical process for removing impurities from high-grade gold concentrate as described in claim 2, characterized in that: The temperature of the sodium carbonate solution is 70℃.

4. The hydrometallurgical process for removing impurities from high-grade gold concentrate as described in claim 1, characterized in that: In S3, the weight ratio of gold concentrate to acetic acid is 1:0.

75.

5. The hydrometallurgical process for removing impurities from high-grade gold concentrate as described in claim 4, characterized in that: The temperature for acetic acid is 70℃.

6. The hydrometallurgical process for removing impurities from high-grade gold concentrate as described in claim 1, characterized in that: In S4, borax is added to sponge gold before casting, and the weight ratio of sponge gold to borax is 1:0.3.