A method for leaching a low-grade lead-zinc ore

Abstract

This invention belongs to the field of lead-zinc ore recovery technology, specifically relating to a leaching method for low-grade lead-zinc ore, comprising the following steps: S1, obtaining low-grade lead-zinc ore; S2, adding the low-grade lead-zinc ore to hydrochloric acid to obtain a leaching system; S3, adding sodium persulfate and hydrogen peroxide to the leaching system for controlled-potential leaching until the redox potential of the leaching system is 500~600mV to obtain a lead-zinc leachate, wherein the molar ratio of sodium persulfate and hydrogen peroxide is (1~5):1; this invention uses sodium persulfate and hydrogen peroxide in a special ratio to prepare an oxidant, and processes low-grade lead-zinc ore through a controlled-potential leaching process. This process achieves enhanced leaching of zinc and lead by controlling the redox potential.

Description

Technical Field

[0001] This invention belongs to the field of lead-zinc ore recovery technology, specifically a leaching method for low-grade lead-zinc ore. Background Technology

[0002] Lead-zinc mines are characterized by a predominance of low-grade ores, a scarcity of high-grade ores, and a high degree of difficulty in beneficiation, making resource extraction challenging. Furthermore, the high concentration of elements such as lead, zinc, and iron presents a series of problems for lead-zinc separation. Mixed lead-zinc ores require beneficiation processes to obtain lead-zinc concentrates. Flotation is the primary beneficiation method for mixed lead-zinc ores, yielding the main raw materials for lead and zinc smelting: lead sulfide and zinc sulfide concentrates. Lead sulfide concentrate is then processed using pyrometallurgical methods to obtain crude lead, while zinc sulfide concentrate is processed using hydrometallurgical or pyrometallurgical methods to obtain crude zinc, thus enabling the extraction of lead and zinc resources.

[0003] With the steady advancement of flotation technology and the increasing development and utilization of lead-zinc ores, high-grade, easily flotable lead-zinc ore resources are dwindling. Therefore, research on low-grade, difficult-to-float lead-zinc ores is receiving increasing attention. Currently, in industry, lead and zinc extraction cannot directly utilize low-grade mixed lead-zinc sulfide ores; complex flotation processes are required to enrich high-grade lead and zinc sulfide concentrates that meet smelting requirements. However, low-grade lead-zinc ores have complex ore types and mineral compositions, low lead and zinc content, and are difficult to enrich using flotation technology. Direct metallurgical processing results in low lead and zinc extraction rates, high investment and operating costs, and significant pollution.

[0004] Current research on low-grade lead-zinc ore mainly focuses on mineral processing, studying how to optimize the processing technology to improve the grade of lead-zinc ore. However, there is relatively little research on directly extracting lead and zinc from low-grade lead-zinc ore through a certain process without mineral processing. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a leaching method for low-grade lead-zinc ore, comprising the following steps:

[0006] S1. Obtain low-grade lead-zinc ore, wherein the composition of the low-grade lead-zinc ore is: Pb 0.5wt%~5.0wt%, Zn 1.0wt%~10.0wt%, Fe 1.0wt%~20.0wt%, K 0.5wt%~3.0wt%, Mn 0.5wt%~3.0wt%, Al 1.0wt%~5.0wt%, S 1.0wt%~20.0wt%, Si 1.0wt%~20.0wt%, O 25.0wt%~50.0wt%;

[0007] S2. The low-grade lead-zinc ore is added to hydrochloric acid to obtain a leaching system;

[0008] S3. Add sodium persulfate and hydrogen peroxide to the leaching system and perform potential-controlled leaching until the redox potential of the leaching system is 500~600mV to obtain lead-zinc leaching solution, wherein the molar ratio of sodium persulfate and hydrogen peroxide is (1~5):1.

[0009] Furthermore, the Pb content in the low-grade lead-zinc ore is any one of 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, or a range between two of them.

[0010] Furthermore, the Zn content in the low-grade lead-zinc ore is any one or a range between two of the following: 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt%, and 10.0wt%.

[0011] Furthermore, the molar ratio of sodium persulfate to hydrogen peroxide can be any one of 1:1, 2:1, 3:1, 4:1, 5:1, or a range between the two.

[0012] Furthermore, the redox potential of the leaching system can be any one of 500mV, 530mV, 550mV, 580mV, 600mV, or any combination thereof.

[0013] Specifically, step S2 involves adding the low-grade lead-zinc ore to hydrochloric acid at a solid-liquid ratio of 1g:(6~10)mL to obtain a leaching system, wherein the concentration of hydrochloric acid is 1~2mol / L.

[0014] Furthermore, the solid-liquid ratio of the low-grade lead-zinc ore and the hydrochloric acid can be any one of 1g:6mL, 1g:7mL, 1g:8mL, 1g:9mL, 1g:10mL, or a range between both.

[0015] Furthermore, the concentration of the hydrochloric acid is any one of 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, or a range between two of them.

[0016] In step S3, the temperature of the controlled potential leaching is 40~90℃;

[0017] Furthermore, the temperature of the controlled potential leaching can be any one of 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃, or a range between any two.

[0018] In step S3, the controlled potential leaching time is 30-60 minutes.

[0019] Furthermore, the controlled potential leaching time can be any one of 30 min, 40 min, 50 min, 60 min, or any range between two of them.

[0020] The process includes the following steps after step S3: S4, adding ammonia water to the lead-zinc leaching solution to obtain lead hydroxide precipitate, and then separating and recovering lead hydroxide and zinc-containing leaching solution through solid-liquid separation.

[0021] The concentration of the ammonia water is 5~8 mol / L.

[0022] The leaching rate of lead is greater than or equal to 99%, and the leaching rate of zinc is greater than or equal to 99%.

[0023] This invention uses sodium persulfate and hydrogen peroxide in a special ratio to prepare an oxidant, and processes low-grade lead-zinc ore through a controlled-potential leaching process. This process achieves enhanced leaching of zinc and lead by adjusting the redox potential. Detailed Implementation

[0024] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a leaching method for low-grade lead-zinc ore, comprising the following steps:

[0026] S1. Obtain low-grade lead-zinc ore, wherein the composition of the low-grade lead-zinc ore is: Pb 0.5wt%~5.0wt%, Zn 1.0wt%~10.0wt%, Fe 1.0wt%~20.0wt%, K 0.5wt%~3.0wt%, Mn 0.5wt%~3.0wt%, Al 1.0wt%~5.0wt%, S 1.0wt%~20.0wt%, Si 1.0wt%~20.0wt%, O 25.0wt%~50.0wt%;

[0027] The low-grade lead-zinc ore in this invention has complex ore types and mineral compositions. The lead and zinc grades in the concentrate after flotation are low and the recovery rate is low, making it difficult to achieve comprehensive utilization of low-grade lead-zinc ore.

[0028] S2. The low-grade lead-zinc ore is added to hydrochloric acid to obtain a leaching system;

[0029] S3. Add sodium persulfate and hydrogen peroxide to the leaching system and perform potential-controlled leaching until the redox potential of the leaching system is 500~600mV to obtain lead-zinc leaching solution, wherein the molar ratio of sodium persulfate and hydrogen peroxide is (1~5):1.

[0030] This invention utilizes controlled-potential leaching by adding an oxidant. The combined action of sodium persulfate and hydrogen peroxide oxidizes some PbS to PbSO4, allowing it to be released as PbCl4 in hydrochloric acid solution. 2- The form of dissolution increases the solution potential, thereby converting PbS and ZnS in low-grade lead-zinc ore into chlorine complexes (Pb, Zn)Cl. m n+ The lead and zinc leaching solution is obtained by leaching into the solution. The inventors of this invention have found that using sodium persulfate and hydrogen peroxide in a molar ratio of (1~5):1 as an oxidant can effectively extract lead and zinc from low-grade lead-zinc ore.

[0031] The composition of the low-grade lead-zinc ore used in this embodiment of the invention is as follows: Pb 3.0wt%, Zn 4.3wt%, Fe 13.2wt%, K 0.5wt%, Mn 0.5wt%, Al 3.7wt%, S 8.5wt%, Si 18.2wt%, O 48.1wt%.

[0032] Example 1

[0033] A leaching method for low-grade lead-zinc ore includes the following steps:

[0034] S1. Obtain low-grade lead-zinc ore;

[0035] S2. The low-grade lead-zinc ore is added to hydrochloric acid to obtain a leaching system, wherein the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:8mL, and the concentration of hydrochloric acid is 2mol / L.

[0036] S3. Add sodium persulfate and hydrogen peroxide to the leaching system and perform controlled-potential leaching until the redox potential of the leaching system is 580mV to obtain a lead-zinc leaching solution. The molar ratio of sodium persulfate to hydrogen peroxide is 1:1, the controlled-potential leaching temperature is 60℃, and the time is 60min.

[0037] The leaching rate of lead was 99.86% and the leaching rate of zinc was 99.65% based on the analysis and calculation of the lead-zinc leaching solution.

[0038] Example 2

[0039] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:9mL, and the concentration of hydrochloric acid is 1mol / L.

[0040] In step S3, the redox potential of the leaching system is 550mV, the molar ratio of sodium persulfate to hydrogen peroxide is 2:1, the leaching temperature is 60℃, and the leaching time is 50min.

[0041] The leaching rate of lead was 99.78% and the leaching rate of zinc was 99.75% based on the analysis and calculation of the lead-zinc leaching solution.

[0042] S4. Add ammonia water dropwise to the lead-zinc leaching solution to obtain lead hydroxide precipitate, and recover lead hydroxide and zinc-containing leaching solution by solid-liquid separation, wherein the concentration of ammonia water is 5 mol / L;

[0043] The calculated precipitation rate of lead was 98.26%.

[0044] Example 3

[0045] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:8mL, and the concentration of hydrochloric acid is 1mol / L.

[0046] In step S3, the redox potential of the leaching system is 600mV, the molar ratio of sodium persulfate to hydrogen peroxide is 3:1, the leaching temperature is 40℃, and the leaching time is 40min.

[0047] The leaching rate of lead was 99.35% and the leaching rate of zinc was 99.57% based on the analysis and calculation of the lead-zinc leaching solution.

[0048] S4. Add ammonia water dropwise to the lead-zinc leaching solution to obtain lead hydroxide precipitate, and then separate the lead hydroxide and zinc-containing leaching solution by solid-liquid separation to recover the solution. The concentration of ammonia water is 8 mol / L.

[0049] The calculated precipitation rate of lead was 98.15%.

[0050] Example 4

[0051] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:7mL, and the concentration of hydrochloric acid is 1mol / L.

[0052] In step S3, the redox potential of the leaching system is 600mV, the molar ratio of sodium persulfate to hydrogen peroxide is 5:1, the leaching temperature is 50℃, and the leaching time is 30min.

[0053] The leaching rate of lead was 99.66% and the leaching rate of zinc was 99.48% based on the analysis and calculation of the lead-zinc leaching solution.

[0054] Example 5

[0055] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:7mL, and the concentration of hydrochloric acid is 1mol / L.

[0056] In step S3, the redox potential of the leaching system is 500mV, the molar ratio of sodium persulfate to hydrogen peroxide is 2:1, the leaching temperature is 90℃, and the leaching time is 30min.

[0057] The leaching rate of lead was 99.79% and the leaching rate of zinc was 99.52% based on the analysis and calculation of the lead-zinc leaching solution.

[0058] Comparative Example 1

[0059] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:5mL, and the concentration of hydrochloric acid is 0.5mol / L.

[0060] The leaching rate of lead was 93.65% and the leaching rate of zinc was 95.58% based on the analysis and calculation of the lead-zinc leaching solution.

[0061] Comparative Example 2

[0062] Unlike Example 1, in step S3, only sodium persulfate is used to adjust the redox potential of the leaching system;

[0063] The leaching rate of lead was 87.57% and the leaching rate of zinc was 85.32% based on the analysis and calculation of the lead-zinc leaching solution.

[0064] Comparative Example 3

[0065] Unlike Example 1, in step S3, only hydrogen peroxide is used to adjust the redox potential of the leaching system;

[0066] The leaching rate of lead was 73.25% and the leaching rate of zinc was 80.46% based on the analysis and calculation of the lead-zinc leaching solution.

[0067] Comparative Example 4

[0068] Unlike Example 1, in step S3, sodium hypochlorite is used to adjust the redox potential of the leaching system, and the concentration of sodium hypochlorite is 3 mol / L.

[0069] The leaching rate of lead was 53.44% and the leaching rate of zinc was 75.65% based on the analysis and calculation of the lead-zinc leaching solution.

[0070] Comparative Example 5

[0071] Unlike Example 5, in step S3, the redox potential of the leaching system is 450 mV;

[0072] The leaching rate of lead was 95.46% and the leaching rate of zinc was 96.35% based on the analysis and calculation of the lead-zinc leaching solution.

[0073] Comparative Example 6

[0074] Unlike Example 1, in step S2, the solid-liquid ratio of low-grade lead-zinc ore to hydrochloric acid is 1g:11mL, and the concentration of hydrochloric acid is 3mol / L.

[0075] The leaching rate of lead was 94.35% and the leaching rate of zinc was 95.17% based on the analysis and calculation of the lead-zinc leaching solution.

[0076] Comparative Example 7

[0077] Unlike Example 1, in step S3, the molar ratio of sodium persulfate to hydrogen peroxide is 6:1;

[0078] The leaching rate of lead was 91.25% and the leaching rate of zinc was 90.62% based on the analysis and calculation of the lead-zinc leaching solution.

[0079] Comparative Example 8

[0080] Unlike Example 1, in step S3, the molar ratio of sodium persulfate to hydrogen peroxide is 0.4:1;

[0081] The leaching rate of lead was 92.28% and the leaching rate of zinc was 90.95% based on the analysis and calculation of the lead-zinc leaching solution.

[0082] This invention involves controlling the potential leaching of low-grade lead-zinc ore with an oxidant to obtain a lead-zinc leachate, followed by the addition of ammonia to precipitate lead hydroxide. First, the low-grade lead-zinc ore is added to a hydrochloric acid solution. Then, an oxidant is added for controlled potential leaching, raising the solution potential to convert PbS and ZnS in the low-grade lead-zinc ore into a chloride complex (Pb, Zn)Cl. m n+ The lead-zinc ore is leached into a solution to obtain a lead-zinc leachate. Finally, ammonia is added dropwise to the leaching solution to precipitate lead hydroxide, thus separating the lead and zinc. This invention treats low-grade lead-zinc ore without mineral processing; the process is simple, environmentally friendly, and can be operated continuously, making it suitable for large-scale industrial applications.

[0083] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A leaching method for low-grade lead-zinc ore, characterized in that, Includes the following steps: S1. Obtain low-grade lead-zinc ore, wherein the composition of the low-grade lead-zinc ore is: Pb 0.5wt%~5.0wt%, Zn 1.0wt%~10.0wt%, Fe 1.0wt%~20.0wt%, K 0.5wt%~3.0wt%, Mn 0.5wt%~3.0wt%, Al 1.0wt%~5.0wt%, S 1.0wt%~20.0wt%, Si 1.0wt%~20.0wt%, O 25.0wt%~50.0wt%; S2. The low-grade lead-zinc ore is added to hydrochloric acid to obtain a leaching system; S3. Add sodium persulfate and hydrogen peroxide to the leaching system and perform potential-controlled leaching until the redox potential of the leaching system is 500~600mV to obtain lead-zinc leaching solution, wherein the molar ratio of sodium persulfate and hydrogen peroxide is (1~5):1; In step S3, the temperature of the controlled potential leaching is 40~90℃; In step S3, the controlled potential leaching time is 30~60 min; The leaching rate of lead is greater than or equal to 99%, and the leaching rate of zinc is greater than or equal to 99%.

2. The leaching method for low-grade lead-zinc ore according to claim 1, characterized in that, Specifically, step S2 involves adding the low-grade lead-zinc ore to hydrochloric acid at a solid-liquid ratio of 1g:(6~10)mL to obtain a leaching system, wherein the concentration of hydrochloric acid is 1~2mol / L.

3. The leaching method for low-grade lead-zinc ore according to claim 1, characterized in that, Following step S3, the following is also included: S4. Add ammonia water dropwise to the lead-zinc leaching solution to obtain lead hydroxide precipitate, and then separate the solid and liquid components to recover lead hydroxide and zinc-containing leaching solution.

4. The leaching method for low-grade lead-zinc ore according to claim 3, characterized in that, The concentration of the ammonia water is 5~8 mol / L.