Short-process high-valued recovery method for copper leaching pregnant solution

Abstract

The invention relates to the technical field of valuable metal recovery and recycling, and provides a short-process high-value recovery method for a copper leaching pregnant solution. According to the method, copper in the copper leaching pregnant solution is converted into copper sulfide, then impurities are removed, zinc is converted into zinc sulfide, effective recovery of copper and zinc in the copper leaching pregnant solution is achieved through a step-by-step vulcanization method, and the obtained copper sulfide slag and zinc sulfide slag meet related product standards and can be directly sold or can be smelted through a pyrogenic process to obtain copper and zinc; the production process of an enterprise is shortened, and the recovery rate of copper and zinc is high. Furthermore, the zinc-removed supernate is neutralized, the generated neutralized slag is stockpiled as solid waste, wastewater can be reused for production, and secondary pollution is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of valuable metal recovery and resource utilization, and in particular to a short-process high-value recovery method for copper leaching precious liquid. Background Art

[0002] Copper-gold concentrate is the main raw material for gold pyrometallurgical enterprises. At present, the smelting of copper-gold concentrate mainly adopts the process of "one-stage roasting (smoke acid production) - roasting sand to collect copper - acid leaching residue cyanide extraction of gold and silver", in which roasting sand to collect copper includes acid leaching, extraction and electrolytic deposition. That is, firstly, metal sulfides such as copper and zinc are converted into water-soluble or acid-soluble sulfates through one-stage roasting, and dilute sulfuric acid is used for leaching during the roasting process. Metal sulfates such as copper and zinc are dissolved in the solution to obtain dilute sulfuric acid leaching solution (i.e. copper leaching precious solution), while gold and silver are insoluble in dilute sulfuric acid and remain in the acid leaching residue. The acid leaching residue is then extracted with cyanidation. Among them, roasting sand to collect copper is an important link in the whole process. The copper leaching precious solution produced after acid leaching contains about 3000-4000 mg / L of copper and about 1000-2000 mg / L of iron. In addition, it also contains some zinc and a small amount of arsenic. At present, the copper leaching precious liquid adopts the "extraction-electrodeposition" process to recover copper, that is, the copper leaching precious liquid is first extracted with an organic solvent to transfer copper from the aqueous phase to the organic phase, and then electrolytic copper is obtained by stripping and electrolytic deposition. This process has the disadvantages of long process flow, high cost, and low copper recovery rate. In addition, the raffinate produced by the process has high acidity, large production volume, and contains a certain concentration of copper. The raffinate is currently mainly neutralized with lime or carbide slag. The disposal process generates a large amount of solid waste and hazardous waste, and some of the valuable metals copper and zinc contained in the raffinate cannot be recovered.

[0003] Chinese invention patent ZL202210181776.2 discloses a method for improving the copper recovery rate in iron-containing copper waste liquid. The method sequentially oxidizes, neutralizes, heats to remove iron, electrolyzes, neutralizes, presses, washes, and acid-dissolves the iron-containing copper solution. By optimizing the iron removal process, the content of copper ions adsorbed and carried by iron ions during removal is greatly reduced, thereby improving the copper recovery rate; at the same time, when the copper content is electrolyzed to a certain level, alkaline solution is used for neutralization, and the obtained copper-containing mud is acid-dissolved again, which increases the content of copper ions in the solution, greatly improves the electrolysis efficiency, and realizes the recovery of copper in the iron-containing copper solution. The method improves the recovery rate of copper electrolysis by optimizing and reducing the adsorption of copper ions during iron ion removal, but the process flow is still relatively long.

[0004] Chinese invention patent CN202410105953.8 discloses a directional impurity separation process for copper electrolytic refining electrolyte, which comprises: mixing the copper electrolytic refining electrolyte and an adsorbent; the adsorbent is a mixture of Sb2O3 and Sb2O5 in a molar ratio of 2.0 to 5.5:1. This method can effectively remove impurities in the copper electrolytic refining electrolyte and realize the recycling of copper therein. However, this method is mainly aimed at removing arsenic impurities in the electrolyte, and does not involve the removal of iron and the recycling of zinc.

[0005] In summary, there is no effective solution in the art to solve the problems of long and complicated process, low copper recovery rate and raffinate that needs to be treated in the current copper leaching precious solution treatment process. Summary of the invention

[0006] In view of this, the present invention provides a short-process high-value recovery method for copper leaching precious liquid. The recovery method provided by the present invention has a short treatment process, a high recovery rate of copper and zinc, and no secondary pollution in the recovery process.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A short-process high-value recovery method for copper leaching precious solution comprises the following steps:

[0009] The copper leaching noble solution and the copper collecting agent are mixed to carry out copper precipitation reaction, and the obtained reaction solution is subjected to mud and water separation to obtain a copper removal supernatant and copper sulfide slag; the copper collecting agent includes one or more of sulfide and hydrosulfide; the oxidation-reduction potential of the copper precipitation reaction is 100-150mv;

[0010] The copper-removed supernatant and the impurity remover are mixed to remove impurities, and the obtained impurity-removed liquid is subjected to mud-water separation to obtain the impurity-removed supernatant and iron-containing waste slag; the impurity remover is an alkaline compound;

[0011] The impurity-removed supernatant and the zinc-collecting agent are mixed to carry out zinc precipitation reaction, and the obtained reaction liquid is subjected to mud-water separation to obtain zinc-removed supernatant and zinc sulfide slag; the zinc-collecting agent includes one or more of sulfide and hydrosulfide; the redox potential of the zinc precipitation reaction is -150 to -200 mv;

[0012] The copper leaching noble solution includes copper ions, arsenic ions, iron ions and zinc ions.

[0013] Preferably, the copper content in the copper leaching noble solution is 3000-4000 mg / L, the iron content is 1000-2000 mg / L, the zinc content is 800-1200 mg / L, and the arsenic content is 20-120 mg / L.

[0014] Preferably, the copper-collecting agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide; the alkaline compound includes one or more of calcium oxide, calcium hydroxide and sodium hydroxide; the zinc-collecting agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide.

[0015] Preferably, the copper deposition reaction time is 30 to 45 minutes.

[0016] Preferably, the copper content in the copper removal supernatant is below 10 mg / L; when the copper content in the copper removal supernatant is higher than 10 mg / L, the copper removal supernatant is returned to the copper precipitation reaction step until the copper content in the obtained copper removal supernatant is below 10 mg / L.

[0017] Preferably, the pH value of the impurity removal is 3.2 to 3.7, and the impurity removal time is 30 to 45 minutes.

[0018] Preferably, the zinc precipitation reaction time is 30 to 45 minutes.

[0019] Preferably, the zinc content in the zinc-removing supernatant is below 10 mg / L; when the zinc content in the zinc-removing supernatant is higher than 10 mg / L, the zinc-removing supernatant is returned to the zinc precipitation reaction step until the zinc content in the obtained zinc-removing supernatant is below 10 mg / L.

[0020] Preferably, after obtaining the zinc-removed supernatant, the method further comprises: neutralizing the zinc-removed supernatant and then performing mud-water separation.

[0021] Preferably, the neutralizing agent used in the neutralization comprises one or more of calcium oxide, calcium hydroxide, sodium hydroxide and carbide slag;

[0022] The pH value of the neutralization is 7.5 to 8.5, and the neutralization time is 30 to 45 minutes.

[0023] The invention provides a short-process high-value recovery method for copper leaching precious liquid, comprising the following steps: mixing the copper leaching precious liquid and a copper collecting agent to carry out a copper precipitation reaction, carrying out mud-water separation on the obtained reaction liquid, and obtaining a copper-removing supernatant and copper sulfide slag; the copper collecting agent comprises one or more of sulfide and hydrosulfide; the oxidation-reduction potential of the copper precipitation reaction is 100-150mv; mixing the copper-removing supernatant and an impurity remover to remove impurities, carrying out mud-water separation on the obtained impurity-removing liquid, and obtaining an impurity-removing supernatant and iron-containing waste slag; the impurity remover is an alkaline compound; mixing the impurity-removing supernatant and a zinc collecting agent to carry out a zinc precipitation reaction, carrying out mud-water separation on the obtained reaction liquid, and obtaining a zinc-removing supernatant and zinc sulfide slag; the zinc collecting agent comprises one or more of sulfide and hydrosulfide; the oxidation-reduction potential of the zinc precipitation reaction is -150--200mv; the copper leaching precious liquid comprises copper ions, arsenic ions, iron ions and zinc ions. The invention first converts the copper in the copper leaching precious solution into copper sulfide, then removes impurities, and then converts the zinc into zinc sulfide. The copper and zinc in the copper leaching precious solution are effectively recovered by a step-by-step sulfidation method. The obtained copper sulfide slag and zinc sulfide slag meet relevant product standards, can be directly sold or smelted by pyrometallurgy to obtain copper and zinc, shortens the production process of the enterprise, has a high recovery rate of copper and zinc, and has no secondary pollution during the recovery process.

[0024] Furthermore, the present invention neutralizes the zinc-removed supernatant, and the generated neutralized slag is stored as solid waste, and the waste water can be reused in production without secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic flow chart of the short-process high-value recovery method for copper leaching precious liquid provided by the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a short-process high-value recovery method for copper leaching precious solution, comprising the following steps:

[0027] The copper leaching noble solution and the copper collecting agent are mixed to carry out copper precipitation reaction, and the obtained reaction solution is subjected to mud and water separation to obtain a copper removal supernatant and copper sulfide slag; the copper collecting agent includes one or more of sulfide and hydrosulfide; the oxidation-reduction potential of the copper precipitation reaction is 100-150mv;

[0028] The copper-removed supernatant and the impurity remover are mixed to remove impurities, and the obtained impurity-removed liquid is subjected to mud-water separation to obtain the impurity-removed supernatant and iron-containing waste slag; the impurity remover is an alkaline compound;

[0029] The impurity-removed supernatant and the zinc-collecting agent are mixed to carry out zinc precipitation reaction, and the obtained reaction liquid is subjected to mud-water separation to obtain zinc-removed supernatant and zinc sulfide slag; the zinc-collecting agent includes one or more of sulfide and hydrosulfide; the redox potential of the zinc precipitation reaction is -150 to -200 mv;

[0030] The copper leaching noble solution includes copper ions, arsenic ions, iron ions and zinc ions.

[0031] Figure 1 The schematic diagram of the process for the short-process high-value recovery of copper leaching precious liquid provided by the present invention is shown below in combination with Figure 1 Provide detailed explanation.

[0032] The present invention mixes a copper leaching precious solution and a copper collecting agent to carry out a copper precipitation reaction, and separates the obtained reaction solution into mud and water to obtain a copper removal supernatant and copper sulfide slag. In the present invention, the copper leaching precious solution is an acid leaching solution obtained after sulfuric acid leaching in the process of roasting sand copper collection; the copper content in the copper leaching precious solution is 3000-4000 mg / L, the iron content is 1000-2000 mg / L, the zinc content is 800-1200 mg / L, and the arsenic content is 20-120 mg / L.

[0033] In the present invention, the copper collecting agent includes one or more of sulfide and hydrosulfide, and more preferably includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide; the oxidation-reduction potential (ORP) of the copper precipitation reaction is 100-150mv, specifically 110mv, 125mv, 130mv or 145mv; the time of the copper precipitation reaction is preferably 30-45min; in the present invention, the amount of copper collecting agent added is controlled according to the target oxidation-reduction potential. In a specific embodiment of the present invention, it is preferred to first add the copper collecting agent to make the oxidation-reduction potential of the reaction system reach the target value, and then start to calculate the reaction time. During the reaction, the oxidation-reduction potential of the system is monitored in real time. If the oxidation-reduction potential exceeds the above range, it is preferred to add the copper collecting agent to regulate the oxidation-reduction potential. The present invention controls the redox potential of the copper precipitation reaction so that the copper in the copper leaching precious solution undergoes a sulfidation reaction to generate copper sulfide, while zinc does not undergo sulfidation under the redox potential, thereby realizing the step-by-step recovery of copper and zinc; in addition, the arsenic in the copper leaching precious solution also undergoes sulfidation in this step to generate arsenic sulfide and enter the copper sulfide slag.

[0034] In the present invention, mud and water separation is performed after the copper precipitation reaction is completed to obtain a copper removal supernatant and copper sulfide slag; the copper content in the copper removal supernatant is preferably less than 10 mg / L; when the copper content in the copper removal supernatant is higher than 10 mg / L, the copper removal supernatant is preferably returned to the copper precipitation reaction step until the copper content in the obtained copper removal supernatant is less than 10 mg / L.

[0035] After obtaining the copper-removing supernatant, the present invention mixes the copper-removing supernatant and an impurity remover to remove impurities, and separates the obtained impurity-removing liquid into mud and water to obtain an impurity-removing supernatant and iron-containing waste slag. In the present invention, the impurity remover is an alkaline compound, preferably including one or more of calcium oxide, calcium hydroxide and sodium hydroxide; the pH value of the impurity removal is preferably 3.2 to 3.7, more preferably 3.5, and the impurity removal time is preferably 30 to 45 minutes; in a specific embodiment of the present invention, the amount of the impurity remover is determined according to the impurity removal pH value. The present invention adds an impurity remover to cause the iron ions in the system to generate iron hydroxide precipitates, and then the iron hydroxide precipitates can be separated by mud and water separation. When the impurity remover is calcium oxide or calcium hydroxide, the impurity remover is converted into calcium sulfate and also enters the waste slag; in addition, part of the arsenic will also be removed during the impurity removal process.

[0036] After obtaining the impurity-removed supernatant, the present invention mixes the impurity-removed supernatant with a zinc-collecting agent to carry out a zinc precipitation reaction, and separates the obtained reaction solution into mud and water to obtain a zinc-removed supernatant and zinc sulfide slag. In the present invention, the zinc-collecting agent preferably includes one or more of sulfide and hydrosulfide, and more preferably includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide; the redox potential of the zinc precipitation reaction is -150 to -200mv, specifically -160mv, -165mv, -180mv or -190mv; the time of the zinc precipitation reaction is preferably 30 to 45min. During the zinc precipitation reaction, zinc ions are sulfided to form zinc sulfide, and then zinc sulfide slag can be obtained by mud and water separation.

[0037] In the present invention, the zinc content in the zinc-removing supernatant is preferably below 10 mg / L; when the zinc content in the zinc-removing supernatant is higher than 10 mg / L, the zinc-removing supernatant is preferably returned to the zinc precipitation reaction step until the zinc content in the obtained zinc-removing supernatant is below 10 mg / L.

[0038] In the present invention, after obtaining the zinc-removing supernatant, it is preferred that the method further includes: neutralizing the zinc-removing supernatant and then performing mud-water separation; the neutralizing agent used in the neutralization preferably includes one or more of calcium oxide, calcium hydroxide, sodium hydroxide and carbide slag; the pH value of the neutralization is preferably 7.5-8.5, more preferably 8, and the neutralization time is preferably 30-45 minutes; after the neutralization is completed, mud-water separation is performed, the supernatant obtained by separation can be reused in production or directly discharged, and the neutralized slag obtained by separation can be stored as solid waste.

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] A gold smelting enterprise leaches copper precious liquid. The raw water copper content is 3340mg / L, the arsenic content is 24.86mg / L, the zinc content is 871.15mg / L, and the iron content is 1900mg / L. Sodium hydrosulfide is used as the copper recovery agent, and the copper recovery reaction ORP is controlled to be 125mv. The reaction time is 30min, and then the mud and water are separated. The copper in the obtained copper removal supernatant is not detected, the arsenic content is 9.58mg / L, the zinc content is 856.59mg / L, and the iron content is 1830mg / L. The generated copper sulfide slag contains 50.83wt% copper, 0.01wt% arsenic, and 0.015wt% zinc, which meets the first-class requirements of "Copper Concentrate" (YS-T318-2007), and the copper recovery rate is more than 99%.

[0042] The copper-removed supernatant enters the impurity removal process, using sodium hydroxide as the impurity removal agent, controlling the pH of the impurity removal reaction to 3.6, and the reaction time to 40 minutes. Then, mud and water separation is carried out to obtain the impurity-removed supernatant and iron-containing waste slag. Copper is not detected in the impurity-removed supernatant, the arsenic content is 3.12 mg / L, the zinc content is 844.8 mg / L, and the iron content is 510 mg / L.

[0043] The impurity-removed supernatant enters the zinc collection process, sodium hydrosulfide is used as the zinc collection agent, the zinc collection reaction ORP is controlled to -165mv, the reaction time is 30min, and then mud and water are separated to obtain zinc removal supernatant and zinc sulfide slag. Copper and arsenic are not detected in the zinc removal supernatant, the zinc content is 1.92mg / L, and the iron content is 450mg / L. The generated zinc sulfide slag contains 47.42wt% zinc and 0.18wt% arsenic, which meets the requirements of the fourth grade of "Zinc Concentrate" (YS / T 320-2014), and the zinc recovery rate is 99.77%.

[0044] The zinc-removing supernatant enters the neutralization process, using calcium hydroxide as a neutralizing agent, and controlling the reaction pH to 8.2. Then, mud and water separation is performed to obtain a neutralized supernatant and a neutralized slag. No copper or arsenic is detected in the neutralized supernatant, and the zinc content is 0.21 mg / L and the iron content is 3.2 mg / L.

[0045] Example 2

[0046] A gold smelting enterprise leaches copper precious liquid. The raw water copper content is 3985mg / L, the arsenic content is 88.43mg / L, the zinc content is 983.22mg / L, and the iron content is 1645mg / L. Sodium sulfide is used as the copper recovery agent, and the copper recovery reaction ORP is controlled to be 135mv. The reaction time is 35min, and then the mud and water are separated. The copper removal supernatant contains 0.68mg / L copper, 10.12mg / L arsenic, 962.12mg / L zinc, and 1532mg / L iron. The generated copper sulfide slag contains 52.25wt% copper, 0.015wt% arsenic, and 0.01wt% zinc, which meets the first-class requirements of "Copper Concentrate" (YS-T318-2007), and the copper recovery rate is 99.98%.

[0047] The copper-removed supernatant enters the impurity removal process, using sodium hydroxide as the impurity removal agent, controlling the impurity removal reaction pH to 3.5, and the reaction time to 30 minutes. After that, mud and water separation is carried out to obtain the impurity-removed supernatant and iron-containing waste slag. Copper is not detected in the impurity-removed supernatant, the arsenic content is 6.45 mg / L, the zinc content is 943.3 mg / L, and the iron content is 489 mg / L.

[0048] The impurity-removed supernatant enters the zinc collection process, using sodium sulfide as a zinc collection agent, controlling the zinc collection reaction ORP to -150mv, the reaction time to 35min, and then performing mud-water separation to obtain zinc removal supernatant and zinc sulfide slag. No copper or arsenic is detected in the zinc removal supernatant, the zinc content is 1.52mg / L, and the iron content is 436mg / L. The generated zinc sulfide slag contains 49.65wt% zinc and 0.12wt% arsenic, meeting the requirements of the fourth grade of "Zinc Concentrate" (YS / T 320-2014), and the zinc recovery rate is 99.83%.

[0049] The zinc-removing supernatant enters the neutralization process, using calcium oxide as a neutralizing agent, and controlling the reaction pH to 8.5. Then, mud and water separation is performed to obtain a neutralized supernatant and a neutralized slag. No copper or arsenic is detected in the neutralized supernatant, and the zinc content is 0.16 mg / L and the iron content is 2.1 mg / L.

[0050] Example 3

[0051] A gold smelting enterprise leaches copper precious liquid. The raw water copper content is 3123mg / L, the arsenic content is 105.12mg / L, the zinc content is 1005.45mg / L, and the iron content is 1132mg / L. Hydrogen sulfide is used as the copper recovery agent, and the copper recovery reaction ORP is controlled to be 110mv. The reaction time is 40min, and then the mud and water are separated. The copper removal supernatant contains 0.18mg / L copper, 6.12mg / L arsenic, 995.42mg / L zinc, and 1056mg / L iron. The generated copper sulfide slag contains 54.23wt% copper, 0.018wt% arsenic, and 0.013wt% zinc, which meets the first-class requirements of "Copper Concentrate" (YS-T318-2007), and the copper recovery rate is 99.99%.

[0052] The copper-removed supernatant enters the impurity removal process, calcium hydroxide is used as the impurity removal agent, the impurity removal reaction pH is controlled to be 3.8, the reaction time is 35 minutes, and then mud and water separation is carried out to obtain impurity-removed supernatant and iron-containing waste slag. The copper content in the impurity-removed supernatant is 0.06 mg / L, the arsenic content is 4.12 mg / L, the zinc content is 968.7 mg / L, and the iron content is 467 mg / L.

[0053] The impurity-removed supernatant enters the zinc collection process, using hydrogen sulfide as the zinc collection agent, controlling the zinc collection reaction ORP to -155mv, the reaction time to 40min, and then performing mud-water separation to obtain zinc removal supernatant and zinc sulfide slag. No copper or arsenic is detected in the zinc removal supernatant, the zinc content is 1.13mg / L, and the iron content is 428mg / L. The generated zinc sulfide slag contains 50.12wt% zinc and 0.06wt% arsenic, meeting the requirements of Grade 4 products in "Zinc Concentrate" (YS / T 320-2014), and the zinc recovery rate is 99.88%.

[0054] The zinc-removing supernatant enters the neutralization process, using carbide slag as a neutralizing agent, controlling the reaction pH to 8.6, and then performing mud-water separation to obtain a neutralized supernatant and a neutralized slag. No copper or arsenic was detected in the neutralized supernatant, the zinc content was 0.06 mg / L, and the iron content was 2.6 mg / L.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A short-process high-value recovery method for copper leaching precious liquid, characterized in that: The following steps are involved: The copper leaching noble solution and the copper collecting agent are mixed to carry out copper precipitation reaction, and the obtained reaction solution is subjected to mud and water separation to obtain a copper removal supernatant and copper sulfide slag; the copper collecting agent includes one or more of sulfide and hydrosulfide; the oxidation-reduction potential of the copper precipitation reaction is 100-150mv; The copper-removed supernatant and the impurity remover are mixed to remove impurities, and the obtained impurity-removed liquid is subjected to mud-water separation to obtain the impurity-removed supernatant and iron-containing waste slag; the impurity remover is an alkaline compound; The impurity-removed supernatant and the zinc-collecting agent are mixed to carry out zinc precipitation reaction, and the obtained reaction liquid is subjected to mud-water separation to obtain zinc-removed supernatant and zinc sulfide slag; the zinc-collecting agent includes one or more of sulfide and hydrosulfide; the redox potential of the zinc precipitation reaction is -150 to -200 mv; The copper leaching noble solution includes copper ions, arsenic ions, iron ions and zinc ions.

2. The recycling method according to claim 1, characterized in that: The copper content in the copper leaching noble solution is 3000-4000 mg / L, the iron content is 1000-2000 mg / L, the zinc content is 800-1200 mg / L, and the arsenic content is 20-120 mg / L.

3. The recycling method according to claim 1, characterized in that: The copper collecting agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide; the alkaline compound includes one or more of calcium oxide, calcium hydroxide and sodium hydroxide; the zinc collecting agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide.

4. The recycling method according to claim 1, characterized in that: The copper deposition reaction time is 30 to 45 minutes.

5. The recycling method according to claim 1, characterized in that: The copper content in the copper removal supernatant is below 10 mg / L; when the copper content in the copper removal supernatant is higher than 10 mg / L, the copper removal supernatant is returned to the copper precipitation reaction step until the copper content in the obtained copper removal supernatant is below 10 mg / L.

6. The recycling method according to claim 1, characterized in that: The pH value of the impurity removal is 3.2-3.7, and the impurity removal time is 30-45 minutes.

7. The recycling method according to claim 1, characterized in that: The zinc precipitation reaction time is 30 to 45 minutes.

8. The recycling method according to claim 1, characterized in that: The zinc content in the zinc-removing supernatant is below 10 mg / L; when the zinc content in the zinc-removing supernatant is higher than 10 mg / L, the zinc-removing supernatant is returned to the zinc precipitation reaction step until the zinc content in the obtained zinc-removing supernatant is below 10 mg / L.

9. The recycling method according to claim 1, characterized in that: After obtaining the zinc-removing supernatant, the method further comprises: neutralizing the zinc-removing supernatant and then performing mud-water separation.

10. The recycling method according to claim 1, characterized in that: The neutralizing agent used in the neutralization comprises one or more of calcium oxide, calcium hydroxide, sodium hydroxide and carbide slag; The pH value of the neutralization is 7.5 to 8.5, and the neutralization time is 30 to 45 minutes.

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