Efficient enrichment and recovery process for indium in indium-containing acid solution

Abstract

The invention relates to a high-efficiency enrichment and recovery process for indium in an indium-containing acid solution, which comprises the following steps of: feeding an indium-tin-containing raw material into a top-blown furnace for smelting, and volatilizing most indium and entering a dust collection system along with smoke dust to obtain indium-containing top-blown furnace smoke dust; carrying out centralized treatment on the indium-containing top-blown furnace smoke dust in an electric furnace to obtain high-indium electric furnace smoke dust; then the high-indium electric furnace smoke dust is subjected to wet treatment, washing is conducted firstly, then sulfuric acid is used for leaching, an acid solution rich in indium, zinc, cadmium and a small amount of tin elements is obtained, and tin is enriched and recycled in the form of acid leaching residues and returned for tin smelting; neutralizing and precipitating the indium-containing acid solution with ammonia water to obtain indium precipitation slag and indium precipitation liquid; washing the indium precipitation residues with water to obtain washed indium residues and washing liquid, and drying the washed indium residues to obtain indium-rich residues. According to the method, indium, tin and other high-value metals can be efficiently separated from the zinc-cadmium slag with low consumption, efficient enrichment and recovery of indium and tin are achieved, zinc and cadmium are recovered in the form of zinc-cadmium slag, and comprehensive recovery and utilization of various valuable metals are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of tin smelting comprehensive recovery, and in particular relates to a treatment process for efficiently enriching and recovering indium in an indium-containing acid solution. Background Art

[0002] Indium is a precious metal with high recycling value. In the tin smelting system, indium entering the tin product not only affects the product quality, but also cannot be recycled, causing losses. Indium is enriched and opened in the tin smelting smoke, reducing the indium entering the tin ingot to affect the quality of tin products, and indium can be comprehensively recycled.

[0003] As the sources of tin raw materials become increasingly complex, the content of elements such as Zn, Cl, Cd, and In in the raw materials increases. During the tin smelting process, these elements will be enriched in the tin smelting dust. This part of the dust is subjected to wet decontamination treatment to produce tin slag and acid solution. The tin slag is returned to the smelting system to achieve the open circuit of Zn, Cl, Cd, and In in the tin smelting process and the enrichment and recovery of tin in the dust. The acid solution is rich in elements such as Zn, Cd, In, and a small amount of Sn. If the acid solution is neutralized with sodium carbonate, zinc cadmium carbonate slag can be obtained. The output of zinc cadmium carbonate slag is large, the indium is too dispersed, the content is low, and a small amount of tin is lost with the zinc cadmium slag. Sponge indium can be obtained by indium extraction, stripping, and replacement with acid solution, but the raffinate still contains some indium and tin that cannot be enriched and recovered.

[0004] At present, the main extraction process and mainstream extraction technology for indium production in the world is extraction-electrolysis, and its basic process flow is: indium-containing raw materials → enrichment → chemical dissolution → purification → extraction → stripping → zinc (aluminum) replacement → sponge indium → electrolytic refining → refined indium. Smelting dust mainly contains metals such as zinc, lead, cadmium and iron, and also contains a small amount of indium. Indium in the dust is mainly In 2 O 3 ,In 2 S 3 andIn 2 (SO 4 ) 3 In the presence of other phases, the acid leaching-solvent extraction method is mainly used to recover indium from smelting dust. This process has good adaptability in some aspects, but with the increase of impurities in the acid solution or the decrease of indium content, the impurity removal process becomes more complicated and the cost increases, and this method gradually becomes unadaptable. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and to propose a treatment process for efficiently enriching and recovering indium in an acid solution, which has a simple and reliable process, low cost and significant economic benefits.

[0006] The purpose of the present invention is achieved by the following technical means: A highly efficient enrichment and recovery process for indium in an indium-containing acid solution, the process steps are as follows: (1) The indium-containing tin raw material is fed into a top-blown furnace for tin smelting. During the smelting process, most of the indium volatilizes and enters the dust collection system with the smoke, obtaining indium-containing top-blown furnace smoke, thereby achieving primary enrichment of indium in the top-blown furnace smoke; (2) delivering the indium-containing top-blown furnace dust obtained in step (1) to an electric furnace for centralized treatment to obtain high-indium electric furnace dust containing 0.8 wt.% to 1.2 wt.% indium, thereby achieving secondary enrichment of indium in the electric furnace dust; (3) The high-indium electric furnace dust obtained in step (2) is sent to a wet process, where most of the chlorine and part of the zinc and cadmium are first washed out with water, and then leached with sulfuric acid to obtain an acid solution rich in indium, zinc, cadmium and a small amount of tin. The tin is enriched and recovered in the form of acid leaching residue and returned to tin smelting; (4) neutralizing and precipitating the indium-containing acid solution obtained in step (3) with ammonia water to obtain indium precipitation slag and indium precipitation liquid; (5) mixing the indium precipitated slag obtained in step (4) with production water or water washing liquid at a liquid-to-solid ratio of L / S=4-5:1, and washing with water at room temperature to obtain water-washed indium slag and water washing liquid; (6) The washed indium slag obtained in step (5) is sent to a drying furnace for drying at a temperature of 140 to 160° C. to obtain indium-rich slag.

[0007] (7) The indium precipitation liquid obtained in step (4) and the water washing liquid obtained in step (5) are dissolved in sulfuric acid, and then sodium carbonate is added to neutralize the zinc-cadmium precipitation to produce zinc-cadmium slag and zinc-cadmium precipitation liquid.

[0008] Furthermore, the temperature of the electric furnace smelting in step (2) is controlled at 1300-1400°C.

[0009] Furthermore, the washing liquid in step (5) is recycled.

[0010] Furthermore, the raffinate after indium extraction or the acid solution with a low indium content can be treated through steps (4), (5), (6), and (7) to achieve the enrichment and recovery of indium in the solution and the treatment of the solution.

[0011] The present invention uses a top-blown furnace to centrally process the indium-containing tin raw materials, and the indium-containing top-blown furnace dust produced is sent to an electric furnace for centralized treatment. Indium is enriched twice to obtain high-indium electric furnace dust. The high-indium electric furnace dust is treated by a wet method to obtain an acid solution rich in indium, zinc, cadmium and a small amount of tin and other elements. The tin can be enriched and recovered in the form of acid leaching slag and returned to the tin smelting system to smelt higher quality tin products, thereby realizing the separation of tin from indium, zinc, cadmium and other elements. Excessive ammonia water is added to the indium-containing acid solution to precipitate elements such as In, Zn, Cd and a small amount of Sn in the acid solution. Under over-alkaline conditions, part of Zn and Cd are dissolved back to undergo complex reaction, and the content of Zn and Cd in the indium precipitated slag is reduced, while the content of In and Sn is increased. Washing the indium precipitated slag with water can remove a large amount of ammonium sulfate, zinc ammonia complex, cadmium ammonia complex, SO 4 2- and NH 4 + Dissolved in water, the indium in the slag is further enriched and improved. The precipitated indium slag is washed with water and then dried at high temperature, which can make the remaining ammonium sulfate and SO 4 2- and NH 4 + Decomposition, crystalline water volatilizes, and the indium content of indium slag is enriched again. After recovering indium and tin, the solution is dissolved in sulfuric acid to form zinc and cadmium ammine complexes, and then zinc and cadmium are recovered by neutralization and precipitation with sodium carbonate, and zinc-cadmium carbonate slag is produced for sale, further creating economic benefits.

[0012] The process of the present invention is combined with the main tin smelting system, making full use of the process of the main tin smelting system, and can separate high-value metals such as indium and tin from zinc-cadmium slag with low consumption and high efficiency, realize the efficient enrichment and recovery of indium and tin, and recover zinc and cadmium in the form of zinc-cadmium slag, thereby realizing the comprehensive recovery and utilization of multiple valuable metals. The process is simple and reliable, and the economic benefits are remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0014] The process of the present invention will be further described below in conjunction with the accompanying drawings of the specification.

[0015] like Figure 1 As shown, a highly efficient indium enrichment and recovery process in an indium-containing acid solution, the specific process steps are as follows: (1) Indium-containing tin raw materials are fed into a top-blown furnace, the ingredients are prepared according to the process requirements for tin smelting, and tin smelting is carried out using the existing top-blown furnace reduction smelting production process. During the smelting process, most of the indium volatilizes and enters the dust collection system with the smoke, obtaining tin smoke containing 0.3wt.% to 0.6wt.% indium, thereby achieving primary enrichment of indium in the top-blown furnace smoke; (2) The indium-containing tin dust obtained in step (1) is sent to an electric furnace for centralized treatment, and the ingredients are prepared according to the process requirements of tin smelting. Tin smelting is carried out using the existing tin smelting electric furnace reduction smelting production process. The tin smelting electric furnace has good sealing performance, small flue gas volume, low smoke rate, and direct conversion of electrical energy in the molten pool into thermal energy, with high thermal efficiency. The smelting temperature of the electric furnace is controlled at 1300 to 1400° C., which is conducive to the re-volatilization and enrichment of indium, thereby obtaining high-indium tin dust containing 0.8 wt.% to 1.2 wt.% of indium, thereby realizing secondary enrichment of indium in the electric furnace dust; (3) The high indium tin smoke obtained in step (2) is subjected to a wet treatment, first washed with water, to make ZnCl 2 , CdCl 2 The chloride salt is dissolved in water and then leached with sulfuric acid to obtain ZnSO 4 、CdSO 4 、In2(SO 4 ) 3 and a small amount of SnCl 4 Acid solution of the same elements. The chemical reaction formula is as follows: ZnO+H 2 SO 4 =ZnSO 4 +H 2 Oh, CdO+H 2 SO 4 =CdSO 4 +H 2 Oh, In 2 O 3 +3H 2 SO 4 =2In(SO 4 ) 3 +3H 2 O, SnO 2 +4HCl=SnCl 4 +2H 2 O; Tin is oxidized and volatilized into SnO through high temperature molten pool. 2 There is a small amount of Cl in the solution. - with SnO 2 The reaction generates SnCl 4 Entering into the solution; SnO 2 It does not react with concentrated sulfuric acid, and most of the tin is enriched and recovered in the form of acid leaching residue, which is returned to the tin smelting system for further tin refining, thus achieving the separation of tin from elements such as indium, zinc, and cadmium; (4) Add ammonia water to the indium acid solution obtained in step (3) for neutralization and precipitation, and control the end point pH to 10. The specific process is as follows: add ammonia water to the indium acid solution at room temperature, control the end point pH to 10, react for 1.5 to 2 hours, and then filter to obtain indium precipitate residue and indium precipitate liquid. Ammonia water is a good precipitant. It can react with a variety of metal ions to generate insoluble weak bases or amphoteric hydroxides. It can react with Zn under alkaline conditions. 2+ 、Cd 2+ A complex reaction occurs. Neutralization with ammonia water can precipitate elements such as Sn, In, Zn, and Cd in the acid solution. Under over-alkaline conditions, some Zn and Cd will dissolve back and undergo a complex reaction. The content of Zn and Cd in the indium slag is reduced, while the content of In and Sn is increased. The chemical reaction formula is as follows: In 2 (SO 4 ) 3 +6NH 3 ·H 2 O=3(NH 4 )2SO 4 +2In(OH) 2 ↓, ZnSO 4 +2NH 3 ·H 2 O =(NH 4 )2SO 4 +Zn(OH) 2 ↓, CdSO 4 +2NH 3 ·H 2 O=(NH 4 )2SO 4 +Cd(OH) 2 ↓, SnCl 4 +4NH 3 ·H 2 O=Sn(OH) 4 ↓+4NH 4 Cl, Zn(OH) 2 +4NH 3 ·H 2 O=[Zn(NH 3 ) 4 ](OH) 2 + 4H 2 Oh, Cd(OH) 2 +4NH 3 ·H 2 O=[Cd(NH 3 ) 4 ](OH) 2+4H 2 O; The ammonia gas, acid mist, etc. generated during the neutralization and precipitation process are collected and sent to the purification treatment system for purification; (5) The indium precipitate slag obtained in step (4) is mixed with production water or water washing liquid at a liquid-to-solid ratio of L / S=4-5:1, washed at room temperature, and filtered after washing to obtain washed slag (indium slag) and water washing liquid, which can be recycled. Washing the indium precipitate slag can produce a large amount of ammonium sulfate, zinc ammine complex, cadmium ammine complex, SO 4 2- and NH 4+ When dissolved in water, the indium contained in the slag is further enriched and increased, and a small amount of tin is also enriched in the slag for recovery.

[0016] (6) The washed slag obtained in step (5) is sent to a drying furnace and dried at 140-160°C to remove the remaining ammonium sulfate and SO 4 2- and NH 4+ Decomposition, crystalline water volatilization, indium slag indium enrichment and increase again, to obtain indium-rich slag, the chemical reaction formula is as follows: 3(NH 4 ) 2 SO 4 =4NH 3 ↑+SO 3 ↑+H 2 O (heating), 3(NH 4 ) 2 SO 4 =3SO 2 ↑+N 2 ↑+6H 2 O (heating); Ammonia, acid mist, etc. generated during the baking process are sent to the purification system for purification; (7) Add sulfuric acid to dissolve the indium precipitation solution obtained in step (4) and the water washing solution obtained in step (5), and then add sodium carbonate to neutralize the zinc-cadmium precipitation to produce zinc-cadmium slag and zinc-cadmium precipitation solution. The chemical reaction formula is as follows: Zn(NH 3 ) 4 ](OH) 2 +3H 2 SO 4 =ZnSO 4 +2(NH 4 ) 2 SO 4 +2H 2 Oh, Cd(NH 3 ) 4 ](OH) 2 +3H2 SO 4 =CdSO 4 +2(NH 4 ) 2 SO 4 +2H 2 Oh, Na 2 CO 3 +ZnSO 4 =ZnCO 3 ↓+Na 2 SO 4 , Na 2 CO 3 +CdSO 4 =CdCO 3 ↓+Na 2 SO 4 .

[0017] The liquid after zinc and cadmium precipitation is sent to the water treatment system.

[0018] (8) The raffinate extracted with indium or the acid solution with a low indium content is treated through steps (4), (5), (6) and (7) to achieve indium enrichment in the solution and treatment of the solution.

[0019] The present invention is combined with the main tin smelting system, and fully utilizes the process of the main tin smelting system, such as the oxidation-reduction smelting process of the top-blown furnace and the electric furnace, the wet impurity removal, and the tin and other valuable metal recovery process. The enrichment and recovery process of indium in the acid solution is simple and reliable, and can recover tin, indium, zinc and other valuable metals in the tin smelting smoke with low consumption and high efficiency, thereby maximizing the comprehensive recovery and utilization of resources and achieving significant economic benefits.

Claims

1. A highly efficient enrichment and recovery process for indium in an indium-containing acid solution, characterized in that: The process steps are as follows: (1) The indium-containing tin raw material is fed into a top-blown furnace for tin smelting. During the smelting process, most of the indium volatilizes and enters the dust collection system with the smoke, obtaining indium-containing top-blown furnace smoke, thereby achieving primary enrichment of indium in the top-blown furnace smoke; (2) delivering the indium-containing top-blown furnace dust obtained in step (1) to an electric furnace for centralized treatment to obtain high-indium electric furnace dust containing 0.8 wt.% to 1.2 wt.% indium, thereby achieving secondary enrichment of indium in the electric furnace dust; (3) The high-indium electric furnace dust obtained in step (2) is sent to a wet process, where most of the chlorine and part of the zinc and cadmium are first washed out with water, and then leached with sulfuric acid to obtain an acid solution rich in indium, zinc, cadmium and a small amount of tin. The tin is enriched and recovered in the form of acid leaching residue and then returned to tin smelting; (4) neutralizing and precipitating the indium-containing acid solution obtained in step (3) with ammonia water to obtain indium precipitation slag and indium precipitation liquid; (5) mixing the indium precipitated slag obtained in step (4) with production water or water washing liquid at a liquid-to-solid ratio of L / S=4-5:1, and washing with water at room temperature to obtain water-washed indium slag and water washing liquid; (6) The washed indium slag obtained in step (5) is sent to a drying furnace for drying at a temperature of 140 to 160° C. to obtain indium-rich slag.

2. The process for efficiently enriching and recovering indium in an indium-containing acid solution according to claim 1, characterized in that: The indium precipitation liquid obtained in step (4) and the water washing liquid obtained in step (5) are dissolved in sulfuric acid, and then sodium carbonate is added to neutralize the zinc-cadmium precipitation to produce zinc-cadmium slag and zinc-cadmium precipitation liquid.

3. The process for efficiently enriching and recovering indium in an indium-containing acid solution according to claim 1 or 2, characterized in that: The electric furnace smelting temperature in step (2) is 1300-1400°C.

4. The process for efficiently enriching and recovering indium in an indium-containing acid solution according to claim 1 or 2, characterized in that: The washing liquid in step (5) is recycled.

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