Method for recovering tin from tin arsenate slag and ammonium chlorostannate substance

Abstract

The invention discloses a method for recovering tin from tin arsenate slag and an ammonium chlorostannate substance, and the method comprises the following specific steps: firstly, mixing the tin arsenate slag with hydrochloric acid, and heating for acid leaching and dissolving to obtain an acid leaching solution rich in arsenic and tin; then adding a tin precipitator into the arsenic and tin acid leaching solution, and selectively and efficiently precipitating tin to realize separation of arsenic and tin; then, an arsenic reducing agent is added into the tin immersion post-solution, and pentavalent arsenic in the solution is reduced into trivalent arsenic; a vulcanizing agent is added into the reduced liquid, and most arsenic is removed through a vulcanization arsenic precipitation method; and finally, carrying out deep treatment on the arsenic-precipitated liquid. According to the method, efficient separation of arsenic and tin in the tin arsenate slag can be achieved, the direct recovery rate of tin can reach 90% or above, the arsenic content of the obtained ammonium chlorostannate tin deposition slag is lower than 1.0%, meanwhile, effective fixation of arsenic is achieved, and the method is environmentally friendly, easy to operate, low in production cost and capable of being used for industrial production.

Description

Technical Field

[0001] The invention relates to a method for recovering tin, and in particular to a method for recovering tin from arsenate tin slag and ammonium chlorostannate substances. Background Art

[0002] Tin is an important basic metal material with excellent properties such as low melting point, soft quality, non-toxicity, corrosion resistance, and good ductility. Therefore, it plays a very wide range of roles in the fields of electronics, food processing, machinery manufacturing, automobile industry, aerospace, and energy storage. With the depletion of original tin resources and the increasing demand for tin, tin-containing secondary resources have become an important alternative source for tin production. In the traditional tin extraction process, tin-containing by-products with different tin contents are produced, including tin-containing tailings (containing 0.1-1.0wt.%), tin-containing middlings (containing 3-5wt.%), tin-containing slag (containing 2-10wt.%), tin-iron hard heads (containing 20-60wt.%), and tin-containing anode mud (containing 40-60wt.%). In addition, tin-containing solid wastes, such as used tinplate, tin alloys, and electronic waste, are also recyclable. It is reported that tin production from renewable resources accounts for nearly 30% of global tin consumption. Therefore, the problem of recovering tin from tin-containing secondary resources has received increasing attention in recent decades.

[0003] Studies have shown that pentavalent arsenic and tetravalent tin will co-precipitate in a high acidity system to form an insoluble arsenic-tin precipitate, the main component of which is tin arsenate. Arsenic-tin slag is produced by arsenic-tin co-precipitation in a high acidity system and has the characteristics of high arsenic and high tin. Since arsenic is highly toxic, how to separate arsenic and tin in arsenic-tin slag and efficiently recover the tin in it is a problem that must be solved at present. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recovering tin from arsenate tin slag and ammonium chlorostannate substances, which can realize efficient separation of arsenic and tin and obtain high-grade tin slag.

[0005] The present invention achieves the above object through the following technical scheme: a method for recovering tin from arsenate tin slag, the method specifically comprising the following steps:

[0006] S1) firstly mixing arsenic acid tin slag with hydrochloric acid, heating and acid leaching to dissolve, and obtaining an acid leaching solution rich in arsenic and tin;

[0007] S2) adding a tin precipitant to the arsenic and tin acid leaching solution obtained in S1) to obtain tin precipitation residue and tin precipitation liquid;

[0008] S3) adding an arsenic reducing agent to the tin precipitation solution obtained in S2) to obtain a reduced solution;

[0009] S4) adding a sulfiding agent to the reduced liquid obtained in S3) and treating it by sulfidation arsenic precipitation method to obtain arsenic sulfide slag and arsenic precipitation liquid;

[0010] S5) sending the arsenic precipitation liquid obtained in S3) to deep treatment.

[0011] Furthermore, the acid leaching conditions of the arsenic acid tin slag in S1) are: the liquid-solid ratio of the arsenic acid tin slag to hydrochloric acid is 4-10:1, the temperature is 75-95° C., and the leaching time is 0.5-1.5 h.

[0012] Furthermore, the concentration of hydrochloric acid in S1) is 4-8 mol / L.

[0013] Furthermore, the conditions for tin precipitation in the arsenic and stannic acid leaching solution in S2) are as follows: temperature 5-85° C., reaction time 0.5-1.5 h, and the amount of tin precipitant used is 2.0-5.0 times the theoretical amount.

[0014] Furthermore, the tin precipitant in S2) is any one of ammonium chloride and tetramethylammonium chloride or a mixture of the two.

[0015] Furthermore, the arsenic reducing agent in S3) is any one of thiourea, ascorbic acid, oxalate, and dithionite, or a mixture of two or more thereof.

[0016] Furthermore, the amount of the arsenic reducing agent in S3) is 2.0-4.0 times the theoretical amount.

[0017] Further, the conditions for arsenic precipitation after reduction in S4) are as follows: temperature 5-85°C, reaction time 1.0-2.0h, and the amount of sulfiding agent added is 2- / As molar ratio is controlled at 2.0-10.0.

[0018] Further, the sulfiding agent in S4) is Na2S, NaHS, H2S, K2S,

[0019] (NH4)2S, BaS and other sulfur-containing compounds, any one or a mixture of two or more thereof.

[0020] Furthermore, the direct recovery rate of tin in the method can reach more than 90%, and the arsenic content of the obtained ammonium chlorostannate tin precipitate slag is less than 1.0%.

[0021] An ammonium chlorostannate substance comprises ammonium chlorostannate and tetramethylammonium chlorostannate, and is prepared by the above method.

[0022] The present invention mainly relates to the following reaction:

[0023] Hydrochloric acid pickling process:

[0024] Sn3(AsO4)4+12HCl→3SnCl4+4H3AsO4

[0025] Sn(HAsO4)2·H2O+4HCl→SnCl4+2H3AsO4+H2O

[0026] SnCl4+2HCl→H2SnCl6

[0027] Tin precipitation process:

[0028] H2SnCl6+2NH4Cl→(NH4)2SnCl6↓+2HCl

[0029] H2SnCl6+2(CH3)4NCl→[(CH3)4N]2SnCl6↓+2HCl

[0030] Arsenic reducing agent reduction process:

[0031] H3AsO4+arsenic reducing agent→H3AsO3

[0032] Arsenic sulfide precipitation process:

[0033] 2H3AsO4+5S 2- +10H + →As2S5↓+8H2O

[0034] H3AsO4+S 2- +2H + →S 0 ↓+H3AsO3+H2O

[0035] 2H3AsO3+3S 2- +6H + →As2S3↓+6H2O

[0036] The beneficial effects of the present invention are as follows: based on the principle of selective precipitation of tin by ammonium chloride substances in a hydrochloric acid system, the present invention adopts a two-step method of "hydrochloric acid leaching + tin precipitation by tin precipitant" to achieve effective separation of arsenic and tin in arsenic acid tin slag and efficient recovery of tin, the direct recovery rate of tin can reach more than 90%, and the arsenic content of the obtained ammonium chlorostannate tin slag is less than 1.0%. Combined with the "arsenic reduction + sulfide precipitation of arsenic" step, pentavalent arsenic is subjected to reduction pretreatment, which solves the problems of slow arsenic precipitation rate and low arsenic precipitation efficiency of pentavalent arsenic, and promotes effective fixation of arsenic. The method has a short process flow, simple operation, good arsenic and tin separation effect, high tin direct recovery rate, high arsenic precipitation efficiency, low cost, and is easy to be applied in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope of protection of the present invention. In each of the drawings, similar components are numbered similarly.

[0038] Figure 1 The XRD spectrum of arsenate tin slag, which is the research object of the embodiment of the present disclosure, is shown;

[0039] Figure 2 The XRD spectrum of ammonium chlorostannate obtained by precipitation of tin with ammonium chloride in the embodiment of the present disclosure is shown;

[0040] Figure 3 The XRD spectrum of tetramethylammonium chlorostannate obtained by precipitation of tin with tetramethylammonium chloride in the embodiment of the present disclosure is shown;

[0041] Figure 4 The SEM spectrum of ammonium chlorostannate obtained by precipitation of tin with ammonium chloride in the embodiment of the present disclosure is shown;

[0042] Figure 5 A schematic flow chart of a method for recovering tin from arsenate tin slag provided in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] like Figure 5 As shown, the present invention provides a method for recovering tin from arsenate tin slag, the method specifically comprising the following steps:

[0045] S1) firstly mixing arsenic acid tin slag with hydrochloric acid, heating and acid leaching to dissolve, and obtaining an acid leaching solution rich in arsenic and tin;

[0046] S2) then adding a tin precipitant to the arsenic and tin acid leaching solution obtained in S1) to selectively and efficiently precipitate tin in the form of ammonium chlorostannate-like substances to achieve separation of arsenic and tin;

[0047] S3) adding an arsenic reducing agent to the tin precipitation solution obtained in S2) to reduce pentavalent arsenic to trivalent arsenic;

[0048] S4) then, adding a sulfiding agent to the reduced solution obtained in S3) and treating it by sulfidation arsenic precipitation method to remove most of the arsenic;

[0049] S5) Finally, the arsenic precipitation liquid obtained in S4) is sent for deep treatment.

[0050] Based on the above technical solution, the present invention can also be improved as follows.

[0051] Furthermore, the hydrochloric acid leaching conditions in S1) are 4-8 mol / L HCl, liquid-to-solid ratio 4-10:1, temperature 75-95°C, and leaching time 0.5-1.5 h. After the leaching reaction is completed, a small amount of insoluble sediment is filtered out, and the leached liquid is sent to the tin precipitation process.

[0052] Further, the conditions for tin precipitation with the tin precipitant in S2) are as follows: temperature 5-85°C, reaction time 0.5-1.5h, and the amount of the tin precipitant is 2.0-5.0 times the theoretical amount. The tin precipitant is any one of ammonium chloride and tetramethylammonium chloride or a mixture of the two. After the tin precipitation reaction is completed, the filter residue is the ammonium chlorostannate-like substance, which can be further washed and dried for sale as a product, or used as a raw material to produce tin ingots, sodium stannate and other products.

[0053] Furthermore, the arsenic reducing agent in S3) is any one of thiourea, ascorbic acid, oxalate, dithionite or a mixture of two or more thereof, and the amount of the arsenic reducing agent is 2.0-4.0 times the theoretical amount.

[0054] Furthermore, the conditions for arsenic precipitation by sulfide in S4) are as follows: temperature 5-85°C, reaction time 1.0-2.0h, S 2- / As molar ratio is controlled at 2.0-10.0. The sulfiding agent is any one of Na2S, NaHS, H2S, K2S, (NH4)2S, BaS and other sulfur-containing compounds or a mixture of two or more thereof. After arsenic precipitation by sulfidation, solid-liquid separation is performed to obtain arsenic sulfide slag and arsenic precipitation post-liquid, wherein the arsenic precipitation post-liquid is returned for acid leaching of arsenic acid tin slag.

[0055] Example 1

[0056] This embodiment provides a method for leaching and tin precipitation of arsenic acid tin slag, comprising:

[0057] Weigh 10g of arsenic acid tin slag, add 80mL 6mol / L HCl at a liquid-to-solid ratio of 8:1, heat and dissolve at 85℃ for 1.0h, and filter a small amount of scum to obtain an acid leaching solution rich in arsenic and tin. At 80℃, add tin precipitant NH4Cl in an amount 2.5 times the theoretical amount, stir and react for 1.0h, filter to obtain ammonium chlorostannate tin precipitate slag, and rinse with clean water 2-3 times to remove the entrained acid leaching solution. The liquid after tin precipitation is retained for subsequent arsenic precipitation treatment. The composition of arsenic and tin acid leaching solutions is as follows:

[0058] Table 1 Composition of arsenic and stannic acid leaching solution (g / L)

[0059] Sn As Sb Fe Zn Cd In Bi 26.93 23.67 1.912 1.425 0.2675 0.2634 0.2353 0.1715

[0060] Embodiment 2-5

[0061] The difference between Examples 2-5 and Example 1 is only that the dosage of the tin precipitant NH4Cl is 3.0 times, 3.5 times, 4.0 times, and 4.5 times, respectively.

[0062] Embodiment 6-7

[0063] The difference between Example 6-7 and Example 1 is that the tin precipitant is tetramethylammonium chloride, and the amount of the tin precipitant is 2 times and 4 times the theoretical amount, respectively.

[0064] Table 2 Effects of Arsenic and Tin Acid Immersion Solutions on Tin

[0065]

[0066]

[0067] Example 8

[0068] This embodiment provides a method for reducing liquid arsenic after tin precipitation, comprising:

[0069] Take 80 mL of the tin precipitation solution obtained in Example 4, add arsenic reducing agent thiourea, the amount of which is 3.0 times the theoretical amount, and react for 1.0 h at room temperature. After the reaction is completed, 93.15% of As(V) is reduced to As(III).

[0070] The composition of the reduced liquid is as follows:

[0071] Table 3 Reduction liquid composition (g / L)

[0072] Sn As(V) As(Ⅲ) Sb Fe Zn Cd In Bi 1.49 1.56 21.23 1.423 1.107 0.2265 0.2051 0.1585 0.1456

[0073] Example 9

[0074] This embodiment provides a method for reducing liquid sulfide precipitation of arsenic, comprising:

[0075] Take 80 mL of the reduced solution obtained in Example 8, add the sulfiding agent Na2S·9H2O, S 2- The molar ratio of arsenic to As is 2.5, the reaction time is 1.5 h at room temperature, and the arsenic precipitate residue and arsenic precipitate liquid are obtained by filtration.

[0076] Examples 10-13

[0077] The difference between Examples 10-13 and Example 9 is only that the amount of vulcanizing agent is S 2- / As molar ratios are 3.5, 4.5, 5.5 and 7.5 respectively.

[0078] Table 4 Effects of the embodiments of liquid sulfide precipitation of arsenic after reduction

[0079]

[0080] The above is a detailed introduction to a method for recovering tin from arsenate tin slag and ammonium chlorostannate substances provided in the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0081] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0082] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0083] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A method for recovering tin from arsenate tin slag, characterized in that: The method specifically comprises the following steps: S1) firstly mixing arsenic acid tin slag with hydrochloric acid, heating and acid leaching to dissolve, and obtaining an acid leaching solution rich in arsenic and tin; S2) adding a tin precipitant to the arsenic and tin acid leaching solution obtained in S1) to obtain tin precipitation residue and tin precipitation liquid; S3) adding an arsenic reducing agent to the tin precipitation solution obtained in S2) to obtain a reduced solution; S4) adding a sulfiding agent to the reduced liquid obtained in S3) and treating it by sulfidation arsenic precipitation method to obtain arsenic sulfide slag and arsenic precipitation liquid; S5) sending the arsenic precipitation liquid obtained in S4) to deep treatment.

2. The method according to claim 1, characterized in that The acid leaching conditions of the arsenic acid tin slag in S1) are: the liquid-solid ratio of the arsenic acid tin slag to the hydrochloric acid is 4-10:1, the temperature is 75-95°C, and the leaching time is 0.5-1.5h; The concentration of the hydrochloric acid is 4-8 mol / L.

3. The method according to claim 1, characterized in that The conditions for tin precipitation in the arsenic and stannic acid leaching solution in S2) are as follows: temperature of 5-85° C., reaction time of 0.5-1.5 h, and dosage of tin precipitant of 2.0-5.0 times of theoretical dosage.

4. The method according to claim 3, characterized in that The tin precipitant in S2) is any one of ammonium chloride and tetramethylammonium chloride or a mixture of the two.

5. The method according to claim 1, characterized in that The arsenic reducing agent in S3) is any one of thiourea, ascorbic acid, oxalate, and dithionite, or a mixture of two or more thereof.

6. The method according to claim 5, characterized in that The amount of the arsenic reducing agent in S3) is 2.0-4.0 times the theoretical amount.

7. The method according to claim 1, characterized in that The conditions for arsenic precipitation after reduction in S4) are as follows: temperature 5-85°C, reaction time 1.0-2.0h, and the amount of sulfiding agent added is 2- / As molar ratio is controlled at 2.0-10.

0.

8. The method according to claim 6, characterized in that The sulfiding agent in the S4) is any one of Na2S, NaHS, H2S, K2S, (NH4)2S, BaS and other sulfur-containing compounds, or a mixture of two or more thereof.

9. The method according to claim 1, characterized in that: The direct recovery rate of tin in the method can reach more than 90%, and the arsenic content of the obtained ammonium chlorostannate tin precipitate slag is less than 1.0%.

10. An ammonium chlorostannate substance, characterized in that: The ammonium chlorostannate-type substances include ammonium chlorostannate and tetramethylammonium chlorostannate, which are prepared by the method according to any one of claims 1 to 9.

Images