Method for efficiently removing elemental sulfur in zinc sulfate leaching slurry by using copper powder

Abstract

The invention relates to the technical field of lead and zinc smelting, in particular to a method for efficiently removing elemental sulfur in zinc sulfate leaching slurry through copper powder. Comprising the following steps that copper powder is added into zinc sulfate leaching liquid or leaching slurry to form first mixed slurry, then the first mixed slurry is subjected to a reaction, and second mixed slurry with elemental sulfur removed is obtained; the pH value of the zinc sulfate leaching solution or leaching slurry is 4.5-5.4, and the content of elemental sulfur in the zinc sulfate leaching solution or leaching slurry is 2.5 g / L or below. According to the method, the copper powder is added into the zinc sulfate leaching solution or the leaching slurry, so that the elemental sulfur in the zinc sulfate leaching solution or the leaching slurry is removed, and the influence of the elemental sulfur is eliminated.

Description

Technical Field

[0001] This invention relates to the field of lead and zinc smelting technology, specifically to a method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder. Background Technology

[0002] Traditional hydrometallurgical zinc refining typically employs a "roasting / reduction-leaching-purification-electrowinning" process. Zinc is leached to obtain a zinc sulfate solution, which is then purified to remove impurities before being electrowinning to extract metallic zinc. Because the zinc sulfate solution in hydrometallurgical zinc refining often contains harmful impurities, the purification and removal of these impurities is a crucial process step. For example, patent publication number CN104016403A, entitled "Method for Removing Impurities from Zinc Sulfate," includes the following steps: a) detecting cadmium and nickel in the refined zinc sulfate solution to be treated; b) preliminary impurity removal: heating the refined zinc sulfate solution to 80-90°C, adding zinc powder with a nickel content of 8-12 times, as well as antimony trioxide and copper sulfate, to make the concentrations of antimony trioxide and copper sulfate in the solution 1.2-1.5 mg / L and 40-45 mg / L, respectively, stirring thoroughly, and reacting for 1-2 hours; c) secondary impurity removal: filtering the liquid obtained in the previous step, and when the filtrate cools to below 50°C, adding zinc powder with a cadmium content of 2-3.5 times, stirring thoroughly, and continuing the reaction until complete. This method has the advantages of low reagent cost and ease of industrial-scale operation. Currently, there are no reports on the treatment of elemental sulfur as an impurity element in zinc sulfate slurry. Therefore, this invention provides a method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder. The aim is to remove elemental sulfur from the zinc sulfate leaching solution or slurry by adding copper powder, thereby eliminating the influence of elemental sulfur.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps: adding copper powder to zinc sulfate leaching solution or leaching slurry to form a first mixed slurry, and then reacting the first mixed slurry to obtain a second mixed slurry after removing elemental sulfur; the pH of the zinc sulfate leaching solution or leaching slurry is 4.5~5.4, and the content of elemental sulfur in the zinc sulfate leaching solution or leaching slurry is below 2.5 g / L.

[0005] The zinc sulfate leaching solution or leaching slurry is: the leaching solution or slurry after neutralization of acidic flue dust to pH=4.5~5.4 at 60~100℃, followed by liquid-solid separation. The flue dust is zinc oxide-containing flue dust generated during the reduction-volatilization roasting of the original ore or the reduction-volatilization roasting of zinc leaching slag in the zinc smelting process. The zinc calcined sand is the product obtained after roasting zinc concentrate, mainly containing zinc oxide, zinc sulfate, zinc sulfide, etc.

[0006] The process of flue gas formation can be as follows: zinc leaching residue is mixed with reducing agents such as coke and coal powder in a certain proportion and then smelted in a kiln. The temperature inside the kiln generally reaches 1100℃~1300℃. At this time, metals such as Zn, Pb and Fe in zinc leaching residue are reduced to elemental form, while Zn and Pb volatilize into the flue gas and are subsequently oxidized to form flue gas. The flue gas is then recovered after being collected by electrostatic precipitator or bag filter.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, the zinc content in the zinc sulfate leachate or leachate slurry is below 170 g / L.

[0009] Furthermore, the weight percentage of copper powder with a particle size of less than 100 μm is 70% to 100%, and the weight content of effective metallic copper is 75% to 100%.

[0010] Furthermore, the copper powder includes at least one of gasified copper powder, sprayed copper powder, electrolytic copper powder, and mechanically ground copper powder.

[0011] Furthermore, the molar ratio of effective metallic copper in the copper powder to elemental sulfur in the zinc sulfate leaching solution or leaching slurry is 1.3 to 3:1.

[0012] Furthermore, the molar ratio of effective metallic copper in the copper powder to elemental sulfur in the zinc sulfate leaching solution or leaching slurry is 1.5~2:1.

[0013] Furthermore, the reaction conditions for the first mixed slurry are: holding at a temperature of 60℃~96℃ for 10min~160min.

[0014] Furthermore, the reaction conditions for the first mixed slurry are: holding at a temperature of 65℃~90℃ for 20min~160min.

[0015] Furthermore, the method also includes the following steps: performing liquid-solid separation on the second mixed slurry to obtain a zinc sulfate solution and leaching residue.

[0016] Furthermore, the elemental sulfur content in the zinc sulfate solution is less than 8 mg / L.

[0017] This invention addresses the issue that during the reduction and volatilization roasting of raw ore or leaching residue, improper oxygen potential control can lead to the reduction of high-valence sulfur in the raw material to elemental sulfur. This elemental sulfur, at temperatures above 450°C, enters the flue gas as vapor. This flue gas is collected through electrostatic precipitators or bag filters, and then subjected to acid leaching. The flue gas forms in a gaseous state and contains extremely fine particles (micrometers). During acid leaching, the elemental sulfur in the flue gas (generally less than 5%) enters the leachate in a molten or semi-molten state. Due to the extremely fine size of the elemental sulfur in the flue gas, and the fact that it is often in a semi-molten or even molten state under leaching conditions, the elemental sulfur and the leachate are miscible. The presence of elemental sulfur increases the viscosity of the leaching slurry, slows down liquid-solid separation, and causes the solution to turn black during subsequent purification to remove impurities such as copper, cadmium, and cobalt, making impurity removal difficult. This invention discovers the presence of elemental sulfur in the solution and its impact on the smelting system. It proposes for the first time to eliminate the impact of elemental sulfur on the smelting system by adding copper powder. The zinc sulfate solution after the removal of elemental sulfur proceeds smoothly in the subsequent solution purification process to remove copper, cobalt, and cadmium. The leaching residue can be incorporated into the original process flow without further treatment.

[0018] The beneficial effects of this invention are: (1) This invention proposes for the first time to remove elemental sulfur from zinc sulfate leaching solution or leaching slurry using copper powder. The effective metallic copper in the copper powder reacts with the elemental sulfur in the zinc sulfate leaching solution or leaching slurry at 60~96℃ to form an inactive compound, copper sulfide precipitate. The copper sulfide enters the leaching residue during liquid-solid separation and does not react with acid in the subsequent acid leaching process. It innovatively proposes to add copper powder before the liquid-solid separation of zinc sulfate slurry or before the solution purification to directly block the influence of elemental sulfur on liquid-solid separation and solution purification.

[0019] (2) The copper powder of the present invention has a good effect on removing elemental sulfur. The content of elemental sulfur in the zinc sulfate solution after removing elemental sulfur is less than 8 mg / L, and the removal rate reaches more than 98%. The present invention is simple, efficient and easy to operate, and does not affect the original production process. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0021] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0022] Description of the source of materials and reagents: The vaporized copper powder was a sample prepared by the Shanghai Alloy Powder Science Research Center; the sprayed copper powder was a product prepared by a metal materials factory in Henan; the electrolytic copper powder was a product prepared by a new materials factory in Shandong; and the mechanically ground copper powder was a product prepared by a new materials company in Hebei.

[0023] Example 1: This embodiment uses a batch of neutral leachate from flue dust from a factory in Xinjiang as raw material. Its main components are shown in Table 1. Table 1. Composition of a neutral leachate from Xinjiang (g / L) A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps ( Figure 1 ): Electrolytic copper powder was added to the neutral leachate with the composition shown in Table 1. 90% of the copper powder had a particle size of -100 μm, where -100 μm refers to particles smaller than 100 μm (this terminology will not be repeated below). The effective metallic copper content in the copper powder was 93%, and the amount of copper powder added was 1.70 kg / m³. 3 (The weight molar ratio of copper powder to elemental sulfur is 1.5:1).

[0024] The slurry containing copper powder was kept at 65℃ for 160 min, followed by liquid-solid separation. Tests showed that the elemental sulfur content in the solution gradually decreased during the heat preservation process. After 160 min, the elemental sulfur content was 3 mg / L, and the removal rate of elemental sulfur reached 99.43%. After liquid-solid separation, the slag mainly consisted of Cu and CuS. The solution after liquid-solid separation entered the solution purification system, and the purification process proceeded smoothly.

[0025] Example 2: This embodiment uses a batch of neutral leaching slurry from a factory in Liaoning Province as raw material. Its main components are shown in Table 2. Table 2. Composition of a neutral leaching pulp from Liaoning Province A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps: Mechanically ground copper powder was added to the slurry with the composition shown in Table 2. The copper powder had a particle size of -100 μm (97%), an effective metallic copper content of 93%, and an addition amount of 1.71 kg / m³. 3 (The weight molar ratio of copper powder to elemental sulfur is 2:1).

[0026] The slurry containing copper powder was kept at 90℃ for 20 minutes, followed by liquid-solid separation. Testing revealed a rapid decrease in elemental sulfur content during the holding period. After 20 minutes, the elemental sulfur content was 2 mg / L, achieving a removal rate of 99.50%. The separated solution then entered a solution purification system, with the purification process proceeding smoothly.

[0027] Example 3: This embodiment uses a batch of neutral leachate from flue dust from a factory in Inner Mongolia as raw material. Its main components are shown in Table 3. Table 3. Composition of a neutral leachate from Inner Mongolia (g / L) A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps: Gasified copper powder was added to the slurry with the composition shown in Table 3. The copper powder had a particle size of -100 μm and accounted for 100% of the total. The effective metallic copper content in the copper powder was 88%, and the amount of copper powder added was 1.38 kg / m³. 3 (The weight molar ratio of copper powder to elemental sulfur is 1.3:1).

[0028] The slurry containing copper powder was kept at 85℃ for 60 min, followed by liquid-solid separation. Testing revealed that the elemental sulfur content in the solution gradually decreased during the holding period, reaching 3 mg / L after 60 min, with a removal rate of 99.36%. The solids after liquid-solid separation mainly existed in the forms of Cu and CuS. The separated solution entered a solution purification system, and the purification process proceeded smoothly.

[0029] Example 4 This embodiment uses a batch of neutral leaching slurry from a factory in Inner Mongolia as raw material. Its main components are shown in Table 4. Table 4. Composition of a neutral leaching pulp from Inner Mongolia A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps: Gasified copper powder was added to the slurry with the composition shown in Table 4. The copper powder had a particle size of -100 μm, accounting for 70%, and the effective metallic copper content in the copper powder was 90%. The amount of copper powder added was 2.32 kg / m³. 3 (The weight molar ratio of copper powder to elemental sulfur is 3:1).

[0030] The slurry containing copper powder was kept at 95℃ for 10 minutes, followed by liquid-solid separation. Testing revealed that the elemental sulfur content in the solution gradually decreased during the holding period, reaching 2 mg / L after 10 minutes, with a removal rate of 99.62%. The solution after liquid-solid separation entered the solution purification system, and the purification process proceeded smoothly.

[0031] Example 5: This embodiment uses a batch of neutral leaching slurry from a factory in Xinjiang as raw material, and its main components are shown in Table 4: Table 5. Composition of a neutral leaching pulp from Shaanxi Province A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder includes the following steps: Spray-dried copper powder was added to the slurry with the composition shown in Table 5. The copper powder had a particle size of -100 μm, accounted for 100%, and contained 96% effective metallic copper. The amount of copper powder added was 3.41 kg / m³. 3 (The weight molar ratio of copper powder to elemental sulfur is 1.6:1).

[0032] The slurry containing copper powder was kept at 80℃ for 100 min, followed by liquid-solid separation. Testing revealed that the elemental sulfur content in the solution gradually decreased during the holding period. After 100 min, the elemental sulfur content was 2 mg / L, achieving a removal rate of 99.81%. The solution after liquid-solid separation entered the solution purification system, and the purification process proceeded smoothly.

[0033] Comparative Example 1 Compared to Example 1, the electric furnace copper powder was replaced with copper powder with a particle size of 100 μm or larger; otherwise, it remained the same as Example 1. Testing revealed that the elemental sulfur content was 81 mg / L, and the elemental sulfur removal rate reached 84.72%.

[0034] Comparative Example 2 Compared to Example 1, the electric furnace copper powder was replaced with copper powder with a particle size of 250 μm or larger, while the rest remained the same as in Example 1. Testing revealed that the elemental sulfur content was 255 mg / L, and the elemental sulfur removal rate reached 51.89%.

[0035] In summary, this invention is the first to propose the removal of elemental sulfur from zinc sulfate leaching solution or leaching slurry using copper powder. The effective metallic copper in the copper powder undergoes a redox reaction with the elemental sulfur in the zinc sulfate leaching solution or leaching slurry at 60℃~96℃, generating an inactive compound, copper sulfide precipitate. The copper sulfide enters the leaching residue during liquid-solid separation and does not react with acid in the subsequent acidic leaching process. The invention also innovatively proposes adding copper powder before liquid-solid separation of the zinc sulfate slurry or before solution purification to directly block the influence of elemental sulfur on liquid-solid separation and solution purification.

[0036] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder, characterized in that, The process includes the following steps: adding copper powder to zinc sulfate leaching solution or leaching slurry to form a first mixed slurry, and then reacting the first mixed slurry to obtain a second mixed slurry after removing elemental sulfur; the pH of the zinc sulfate leaching solution or leaching slurry is 4.5~5.4, and the content of elemental sulfur in the zinc sulfate leaching solution or leaching slurry is below 2.5 g / L.

2. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 1, characterized in that, The zinc content in the zinc sulfate leachate or leachate slurry is below 170 g / L.

3. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 1, characterized in that, The copper powder has a particle size of less than 100 μm, accounting for 70% to 100% by weight, and the effective metallic copper content is 75% to 100% by weight.

4. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 3, characterized in that, The copper powder includes at least one of vaporized copper powder, sprayed copper powder, electrolytic copper powder, and mechanically ground copper powder.

5. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 1, characterized in that, The molar ratio of effective metallic copper in the copper powder to elemental sulfur in the zinc sulfate leaching slurry is 1.3~3:

1.

6. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 1, characterized in that, The molar ratio of effective metallic copper in the copper powder to elemental sulfur in the zinc sulfate leaching slurry is 1.5~2:

1.

7. A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to any one of claims 1 to 6, characterized in that, The reaction conditions for the first mixed slurry are: holding at a temperature of 60℃~96℃ for 10min~160min.

8. A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to any one of claims 1 to 6, characterized in that, The reaction conditions for the first mixed slurry are: holding at a temperature of 65℃~90℃ for 20min~160min.

9. A method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to any one of claims 1 to 6, characterized in that, It also includes the following steps: performing liquid-solid separation on the second mixed slurry to obtain zinc sulfate solution and leaching residue.

10. The method for efficiently removing elemental sulfur from zinc sulfate leaching slurry using copper powder according to claim 9, characterized in that, The zinc sulfate solution contains less than 8 mg / L of elemental sulfur.

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