Method for recycling zinc smelting tailings

Abstract

The invention discloses a method for recycling zinc smelting tailings, which comprises the following steps of: sieving the dried zinc smelting tailings, classifying and sampling, leaching coarse fraction by hydrochloric acid to obtain a leaching solution I and lead chloride slag, mixing the leaching solution with fine fraction tailings, adjusting the pH value of the solution to be neutral to obtain neutralized slag and neutralized liquid, and recycling the neutralized slag and the neutralized liquid. The neutralized liquid is subjected to replacement to obtain replacement slag and a replacement liquid, the replacement liquid is subjected to iron removal purification electrodeposition casting to obtain a zinc ingot, the replacement slag is subjected to acid leaching again to obtain copper slag and a leaching solution, and the germanium-gallium-indium leaching solution is subjected to extraction and electrolytic refining to obtain germanium concentrate, metal gallium and metal indium; the lead chloride slag is leached through sulfuric acid to obtain lead sulfate slag, the lead sulfate slag is subjected to pyrogenic process lead smelting to recover lead metal, a leaching solution II is subjected to hydrochloric acid and sulfuric acid separation, and a sulfuric acid solution and a hydrochloric acid solution are obtained and can be recycled. The method is high in recovery rate and low in production cost, and the purposes of low-pollution, low-carbon and economical industrial production and rare and precious metal recycling are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of zinc smelting tailings recovery, and in particular relates to a method for recovering zinc smelting tailings. Background Art

[0002] Zinc concentrate is the main raw material for the zinc smelting industry. At present, zinc smelting is mainly based on hydrometallurgical zinc smelting, which accounts for about 85% of zinc production; pyrometallurgical zinc smelting accounts for 15%. The leaching slag obtained from the conventional hydrometallurgical zinc smelting process has a low recovery rate of valuable metals such as copper, indium, gallium and germanium. Pyrometallurgical zinc smelting is mainly based on the ISP process, but the lead and zinc content in the slag can reach 6~10%. After volatilization in the fuming furnace, the lead and zinc content in the slag can be reduced to 2~3%. This part of lead and zinc is difficult to recycle. Although the current treatment methods for zinc smelting slag include fuming furnace volatilization method, hot acid leaching method, thiourea method, etc., the comprehensive recovery effect of zinc, copper and germanium is not ideal, and these methods have potential hazards to the environment. For the above reasons, a large amount of lead and zinc smelting slag in my country is mainly treated by open-air storage or simple landfill. On the one hand, it not only occupies a large area of ​​land, causing a shortage of land resources; on the other hand, these lead smelting slags are exposed to natural weathering and leaching, and the metal elements in the slag will be released into the atmosphere, water bodies and soil, becoming an important source of pollution. At the same time, a large amount of valuable metals in lead and zinc smelting slag, such as lead, zinc, iron, etc., are potential secondary resources. If not properly treated, it will cause a waste of metal resources.

[0003] Therefore, this paper proposes a method for recycling zinc smelting tailings. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for recycling zinc smelting tailings. The method adopts a comprehensive process of normal pressure hydrochloric acid leaching and two-stage leaching process. The process can effectively separate various metals in zinc smelting tailings, has the characteristics of high recovery rate, low production cost, meeting product quality requirements, and repeated utilization of acid solution, thus realizing low-pollution, low-carbon economic industrial production and the purpose of recycling rare and precious metals.

[0005] In order to achieve the above technical effects, the present invention is implemented by the following technical scheme: a method for recycling zinc smelting tailings, specifically comprising the following steps: S1. Screen the dried zinc smelting tailings into fine-grained (<5mm) and coarse-grained tailings (5-15mm); The weight percentage of each component of the zinc smelting tailings includes: 2-20% zinc, 20-25% lead, 2-15% iron, 0.2-1% indium, 0.3-1% gallium, 0.1-1% germanium, and the remainder is impurities; S2, subjecting the coarse-grained tailings obtained in S1 to two-stage leaching with hydrochloric acid to obtain leachate I and lead chloride slag; Furthermore, the leaching solution I is a chlorinated solution of zinc chloride, iron and valuable metals.

[0006] S3, adding the fine-grained tailings obtained in S1 to the leachate I obtained in S2 for pre-neutralization, neutralizing the hydrochloric acid in the solution to make the solution pH reach 6-8, obtaining neutralized slag and neutralized liquid, and the neutralized slag can be added to the coarse-grained tailings for two-stage leaching by hydrochloric acid; synchronously, leaching the lead chloride slag obtained in S2 by sulfuric acid with a mass concentration of 100-130g / L, the ratio of leached slag to sulfuric acid is 4-6:1, the leaching condition is room temperature, the reaction time is 48h, and finally obtaining leachate II and lead sulfate slag; Furthermore, the neutralized liquid in S3 is a metal chloride solution, and the neutralization reaction conditions are a reaction temperature of 45° C., a liquid-to-solid ratio of 8-10:1, a leaching reaction time of 5-6 hours, and a neutralization pH of 6-8.

[0007] Furthermore, the leaching solution II obtained in S3 is a mixed solution of sulfuric acid and hydrochloric acid.

[0008] S4. Zinc powder and iron powder can be added to the neutralized liquid to obtain a replaced liquid and a replaced slag, and finally valuable metals zinc, copper, germanium, gallium and indium can be obtained in the solution and the slag; Based on the above, the replaced liquid is further subjected to four steps of iron removal, purification, electrowinning and smelting to obtain zinc ingots.

[0009] Based on the above, the replacement slag is further leached with acid to obtain copper slag and valuable metal germanium, gallium and indium leaching solution that can be sold.

[0010] Based on the above, the solution required for acid leaching is hydrochloric acid, and its mass concentration is 160-200g / L.

[0011] Based on the above, the germanium-gallium-indium leaching solution is firstly subjected to a full extraction method, wherein the acidity of the extract is adjusted and added to tannin to generate a tannin germanium precipitate, which is then oxidized and roasted to obtain a germanium concentrate; the tannin mother liquor is neutralized to precipitate gallium, the gallium precipitate is decomposed by hydrochloric acid, the filtrate and the residual liquid of the chlorinated distilled germanium are combined, the gallium is extracted with ammonium acetate, and then back-extracted with water, the back-extracted liquid is alkalized with NaOH to prepare a liquid, and then electrolyzed to obtain high-purity gallium; finally, P204 is added to the back-extracted liquid to extract indium, and back-extracted with hydrochloric acid to obtain a back-extracted liquid containing indium, and zinc powder is added to replace it to obtain sponge indium, which is pressed into a mass and subjected to alkali fusion electrolysis to obtain high-purity indium.

[0012] Based on the above, the germanium precipitate is tannin germanium precipitate, and the ratio of the replaced iron powder and zinc powder to the neutralization solution is 1:1:4-6.

[0013] S5, separating the leaching solution II obtained in S3 to obtain a sulfuric acid solution and a hydrochloric acid solution, wherein the sulfuric acid solution is returned to the sulfuric acid leaching process, and the hydrochloric acid is returned to the hydrochloric acid leaching process, so as to be recycled; Furthermore, the separation method in S5 is a distillation separation method, and the distillation temperature is 110-120° C. and the obtained sulfuric acid concentration is 100-130 g / L.

[0014] The beneficial effects of the present invention are: The invention specifically comprises the following steps: subjecting zinc smelting tailings to two-stage hydrochloric acid leaching, and then separating valuable metals from zinc and iron in a replacement manner; zinc and iron are separated and recovered by processes such as iron removal and electrolysis; valuable metals are separated by acid leaching, copper slag, germanium, gallium, indium and the like are dissolved in a solution, and concentrate and metal elements are obtained by segmented extraction and electrolysis; lead slag is leached by sulfuric acid and then smelted by pyrometallurgy to recover lead concentrate, thereby achieving separation and recovery of germanium, gallium, indium, zinc, iron and lead; leachate is recovered by distillation, and can be re-invested in sulfuric acid leaching and hydrochloric acid leaching processes, thereby achieving repeated use of hydrochloric acid and sulfuric acid, and further reducing cost investment and environmental pollution; As described above, the present invention aims at the high content of valuable metals in zinc smelting tailings, and uses green economic technology to recover various valuable metals, thereby achieving the purpose of comprehensive recycling of valuable metals such as zinc, lead, iron, gallium, germanium, and indium. It provides ideas for the recycling of zinc smelting tailings and valuable metals, guides the design of valuable metal recovery, and promotes the sustainable development of green recovery of valuable metals in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for describing the embodiment are briefly introduced below. Those skilled in the art can also obtain other drawings based on these drawings without paying any creative work.

[0016] Figure 1 is a flow chart of the method of the present invention; Figure 2 The XRD spectrum of the fine-grained (<5 mm) particles in the embodiment of the present invention contains metal oxides SnO2, iron oxide (Fe 0.9630 O), zinc oxide (ZnO), lead oxide (PbO), metal phases of lead (Pb), iron (Fe), copper (Cu), zinc (Zn), antimony (Sb), alloy phases of copper-tin alloy (CuSn), tin-antimony alloy (SnSb); Figure 3The XRD spectrum of the coarse-grained grade (5 mm to 15 mm) in the embodiment of the present invention, wherein the metal oxides include silicon dioxide (SiO2) and zinc oxide (ZnO), the metal phases include metal lead (Pb), metal iron (Fe), metal copper (Cu), metal zinc (Zn), metal antimony (Sb), and metal tin (Sn), and the alloy phases include tin-antimony alloy (SbSn); Figure 4 The XRD spectrum of the coarse-grained grade (>15 mm) in the embodiment of the present invention, wherein the metal oxide includes zinc oxide (ZnO), the metal phase includes metal lead (Pb), metal iron (Fe), and metal antimony (Sn), and the alloy phase includes copper-tin alloy (Cu3Sn) and tin-antimony alloy (SbSn); In the accompanying drawings, the components represented by the reference numerals are listed as follows: DETAILED DESCRIPTION

[0017] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. Example 1

[0018] like Figures 1 to 4 As shown, in this embodiment, the inventors recover valuable metals in zinc smelting tailings while reducing the recovery cost and pollution to the environment; therefore, a method for recycling zinc smelting tailings is provided, which specifically includes the following steps: S1. The dried zinc smelting tailings are screened and divided into fine-grained grade (<5mm) and coarse-grained grade (5-15mm). The fine-grained grade is subjected to high-energy ball milling, and the material whose particles pass through an 80-mesh sieve is used as a sample. The coarse-grained grade is sampled by a bench drill, and the materials <5mm and 15-5mm are respectively taken as samples, of which the materials <5mm are taken as fine-grained grade; The weight percentage of each component of the zinc smelting tailings includes: 2-20% zinc, 20-25% lead, 2-15% iron, 0.2-1% indium, 0.3-1% gallium, 0.1-1% germanium, and the remainder is impurities; S2, subjecting the coarse-grained tailings obtained in S1 to two-stage leaching with hydrochloric acid to obtain leachate I and lead chloride slag; Furthermore, the leaching solution I is a chlorinated solution of zinc chloride, iron and valuable metals.

[0019] S3, adding the fine-grained tailings obtained in S1 to the leachate I obtained in S2 for pre-neutralization, neutralizing the hydrochloric acid in the solution to make the solution pH reach 6-8, obtaining neutralized slag and neutralized liquid, and the neutralized slag can be added to the coarse-grained tailings for two-stage leaching by hydrochloric acid; synchronously, leaching the lead chloride slag obtained in S2 by sulfuric acid with a mass concentration of 100-130g / L, the ratio of leached slag to sulfuric acid is 4-6:1, the leaching condition is room temperature, the reaction time is 48h, and finally obtaining leachate II and lead sulfate slag; Furthermore, the neutralized liquid in S3 is a metal chloride solution, and the neutralization reaction conditions are a reaction temperature of 45° C., a liquid-to-solid ratio of 8-10:1, a leaching reaction time of 5-6 hours, and a neutralization pH of 6-8.

[0020] Furthermore, the leaching solution II obtained in S3 is a mixed solution of sulfuric acid and hydrochloric acid.

[0021] S4. Zinc powder and iron powder can be added to the neutralized liquid to obtain a replaced liquid and a replaced slag, and finally valuable metals zinc, copper, germanium, gallium and indium can be obtained in the solution and the slag; Based on the above, the replaced liquid is further subjected to four steps of iron removal, purification, electrowinning and smelting to obtain zinc ingots.

[0022] Based on the above, the replacement slag is further leached with acid to obtain copper slag and valuable metal germanium, gallium and indium leaching solution that can be sold.

[0023] Based on the above, the solution required for acid leaching is hydrochloric acid, and its mass concentration is 160-200g / L.

[0024] Based on the above, the germanium-gallium-indium leaching solution is firstly subjected to a full extraction method, wherein the acidity of the extract is adjusted and added to tannin to generate a tannin germanium precipitate, which is then oxidized and roasted to obtain a germanium concentrate; the tannin mother liquor is neutralized to precipitate gallium, the gallium precipitate is decomposed by hydrochloric acid, the filtrate and the residual liquid of the chlorinated distilled germanium are combined, the gallium is extracted with ammonium acetate, and then back-extracted with water, the back-extracted liquid is alkalized with NaOH to prepare a liquid, and then electrolyzed to obtain high-purity gallium; finally, P204 is added to the back-extracted liquid to extract indium, and back-extracted with hydrochloric acid to obtain a back-extracted liquid containing indium, and zinc powder is added to replace it to obtain sponge indium, which is pressed into a mass and subjected to alkali fusion electrolysis to obtain high-purity indium.

[0025] Based on the above, the germanium precipitate is tannin germanium precipitate, and the ratio of the replaced iron powder and zinc powder to the neutralization solution is 1:1:4-6.

[0026] S5, separating the leachate II obtained in S3 to obtain a sulfuric acid solution and a hydrochloric acid solution, wherein the sulfuric acid solution is returned to the sulfuric acid leaching process, and the hydrochloric acid is returned to the hydrochloric acid leaching process; Furthermore, the separation method in S5 is a distillation separation method, and the distillation temperature is 110-120° C. and the obtained sulfuric acid concentration is 100-130 g / L. Example 2

[0027] Based on the above Example 1, the inventors conducted an X-ray fluorescence spectrum analysis on the smelting slag tailings selected in Example 1 as shown in Table 1 below: Table 1 (X-ray fluorescence spectrum analysis results of smelting tailings in the embodiment of the present invention)

[0028] The conclusion is: the main elements of the smelting tailings are iron and lead, with the iron and lead content reaching 55-60%, followed by tin, zinc, antimony, and copper, which account for about 20%. The silver, gallium, and germanium content are high, reaching 5kg / t, 4kg / t, and 2kg / t respectively. From the composition point of view, the smelting tailings have a great recycling value; At the same time, as shown in Table 2 below, the inventors also conducted a full element chemical analysis on the smelting slag tailings selected in Example 1: Table 2 (Complete element chemical analysis results of smelting slag tailings in the embodiment of the present invention)

[0029] The conclusion is: the silver, germanium (Nb), indium (In), and gallium (Ga) in the table have high contents and have great recycling value. From the distribution of elements in samples of different particle sizes, iron, lead, tin, copper, gallium, and indium are evenly distributed in samples of various particle sizes, while zinc, antimony, silver, germanium, and silicon dioxide are more distributed in fine-grained samples and have lower contents in bulk samples with high metal content. Example 3

[0030] Based on the above Example 1, 80 g of fine-grained tailings were selected, and leaching experiments were carried out on metals such as iron, zinc, germanium, indium, and copper under the conditions of a hydrochloric acid ratio of 1:8, a reaction temperature of 45° C., and a reaction time of 6 h.

[0031] Table 3 (Results of hydrochloric acid two-stage countercurrent coarse tailings leaching experiment)

[0032] As shown in Table 3, with the increase of hydrochloric acid dosage, the leaching rates of Zn, Ge, In, Cu, Ga, Ni, Sn, and Fe all increase. When the hydrochloric acid dosage reaches 160 g / L, the leaching rates of Zn, In, Cu, Ni, Sn, Fe and other elements can reach more than 95%, while the leaching rate of Ge can reach 84.48%, and the leaching rate of Ga can reach 94.03%; if the dosage of hydrochloric acid is further increased, the leaching rate does not change significantly. Example 4

[0033] Based on the above Example 1, 80 g of coarse-grained tailings were selected, and a two-stage countercurrent leaching experiment of hydrochloric acid was carried out on metals such as iron, zinc, germanium, indium, and copper under the conditions of a hydrochloric acid ratio of 1:8, a reaction temperature of 25°C, and a reaction time of 48 h.

[0034] Table 4 (Experimental results of hydrochloric acid two-stage countercurrent coarse-grained tailings leaching in the embodiment of the present invention)

[0035] As shown in Table 4, it can be seen from the above embodiments that, by using hydrochloric acid as the leaching agent and adopting a two-stage leaching process to treat the coarse-grained tailings, under optimized process conditions, the leaching rates of Zn, Cu, Ni, Sn, and Fe can all reach more than 99%, the leaching rates of In and Ga can reach more than 98%, and the leaching rate of Ge can reach more than 93%, thereby achieving efficient leaching of valuable metals such as Ge, In, and Ga in the coarse-grained tailings.

[0036] Based on Examples 2-4, the inventors found that multi-stage acid leaching combined with extraction electrolysis can effectively recover valuable metals in zinc smelting slag, and the recovery rate of each metal is as high as over 90%, and the purity of the valuable metals after electrolysis is high, meeting the quality requirements of the product.

[0037] In summary, the present invention is based on the understanding of zinc smelting slag, targeting the characteristics of high valuable metal content in zinc smelting slag, and uses low-carbon economic technology to recover various valuable metals. It provides ideas for the innovative recycling of zinc smelting slag, guides the design of zinc smelting, and promotes the sustainable development of green zinc smelting in the future. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the attached claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for recycling zinc smelting tailings, characterized in that: The specific steps include: S1. Screen the dried zinc smelting tailings into fine-grained (<5mm) and coarse-grained tailings (5-15mm); The weight percentage of each component of the zinc smelting tailings includes: 2-20% zinc, 20-25% lead, 2-15% iron, 0.2-1% indium, 0.3-1% gallium, 0.1-1% germanium, and the remainder is impurities; S2, subjecting the coarse-grained tailings obtained in S1 to two-stage leaching with hydrochloric acid to obtain leachate I and lead chloride slag; S3, adding the fine-grained tailings obtained in S1 to the leachate I obtained in S2 for pre-neutralization, neutralizing the hydrochloric acid in the solution to make the solution pH reach 6-8, obtaining neutralized slag and neutralized liquid, and the neutralized slag can be added to the coarse-grained tailings for two-stage leaching by hydrochloric acid; synchronously, leaching the lead chloride slag obtained in S2 by sulfuric acid with a mass concentration of 100-130g / L, the ratio of leached slag to sulfuric acid is 4-6:1, the leaching condition is room temperature, the reaction time is 48h, and finally obtaining leachate II and lead sulfate slag; S4. Zinc powder and iron powder can be added to the neutralized liquid to obtain a replaced liquid and a replaced slag, and finally valuable metals zinc, copper, germanium, gallium and indium can be obtained in the solution and the slag; S5. Separate the leaching solution II obtained in S3 to obtain a sulfuric acid solution and a hydrochloric acid solution. The sulfuric acid solution is returned to the sulfuric acid leaching process, and the hydrochloric acid is returned to the hydrochloric acid leaching process.

2. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The leaching solution I is a chlorinated solution of zinc chloride, iron and valuable metals.

3. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The neutralized liquid in S3 is a metal chloride solution, and the neutralization reaction conditions are a reaction temperature of 45° C., a liquid-to-solid ratio of 8-10:1, a leaching reaction time of 5-6 hours, and a neutralization pH of 6-8.

4. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The leaching solution II obtained in S3 is a mixed solution of sulfuric acid and hydrochloric acid.

5. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The replaced liquid is subjected to four steps of iron removal, purification, electrowinning and melting and casting to obtain a zinc ingot.

6. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The replacement slag is subjected to acid leaching to obtain copper slag and valuable metal germanium, gallium and indium leaching solution which can be sold.

7. The method for recycling zinc smelting tailings according to claim 6, characterized in that: The solution required for the acid leaching is hydrochloric acid, and its mass concentration is 160-200g / L.

8. The method for recycling zinc smelting tailings according to claim 6, characterized in that: The germanium-gallium-indium leaching solution is firstly prepared by a full extraction method, wherein the acidity of the extract is adjusted and added to tannin to generate tannin germanium precipitate, and the germanium concentrate is obtained by oxidation roasting; the tannin mother liquor is neutralized to precipitate gallium, the gallium precipitate is decomposed by hydrochloric acid, the filtrate and the residual liquid of chlorinated distilled germanium are combined, the gallium is extracted with acetic acid amine, and then back-extracted with water, the back-extracted liquid is alkalized with NaOH to prepare liquid, and electrolyzed to obtain high-purity gallium; finally, P204 is added to the back-extracted liquid to extract indium, and back-extracted with hydrochloric acid to obtain a back-extracted liquid containing indium, and zinc powder is added to replace to obtain sponge indium, and the lumps are pressed and alkali-melted and electrolyzed to obtain high-purity indium.

9. The method for recycling zinc smelting tailings according to claim 8, characterized in that: The germanium precipitate is tannin germanium precipitate, and the ratio of the replaced iron powder and zinc powder to the neutralizing solution is 1:1:4-6.

10. The method for recycling zinc smelting tailings according to claim 1, characterized in that: The separation method in S5 is a distillation separation method, the distillation temperature is 110-120° C., and the obtained sulfuric acid concentration is 100-130 g / L.

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