Method for efficiently recovering tin resource in smoke dust of tin fuming furnace and preparing stannous sulfate

Abstract

The invention discloses a method for efficiently recovering tin resources in smoke dust of a fuming furnace and preparing stannous mono-sulphate, and belongs to the technical field of secondary tin resource recovery. The method comprises the following steps: carrying out oxidation leaching on the smoke dust of the tin fuming furnace by adopting a H2O2-H2SO4 mixed solution at 60-80 DEG C, and carrying out reduction, impurity removal and concentration crystallization on the obtained leachate to obtain a stannous mono-sulphate product; according to the method, SnS in the smoke dust of the fuming furnace is converted into stannous sulfate in an acidic oxidation environment in a high-selectivity manner, so that efficient recovery and value-added utilization of secondary tin resources are realized, an economic and environment-friendly raw material source is provided for production of stannous sulfate, and a production path of stannous sulfate is widened.

Description

Technical Field

[0001] The invention relates to a method for treating smoke from a tin fuming furnace, in particular to a method for efficiently recovering tin resources from the smoke from a tin fuming furnace and preparing stannous sulfate, belonging to the technical field of recycling tin-containing secondary resources. Background Art

[0002] The smoke from the tin fuming furnace is a tin-containing byproduct formed during the high-temperature gasification and condensation stages of cassiterite smelting. It is rich in valuable metal tin and is accompanied by impurities such as zinc, arsenic, iron, and silicon. It has a high recycling value. Due to the small size of the smoke particles and the large specific surface area, the metal elements exist in the form of oxides, sulfides, etc., which makes it difficult to recycle.

[0003] In traditional treatment methods, the smoke from the tin fuming furnace is usually directly stored or simply landfilled, which not only causes a waste of resources, but also may cause environmental pollution. Some processes use smelting recovery treatment, but the energy consumption is high, the secondary pollution is serious, and the tin recovery rate is low. In contrast, the fine recovery of smoke through hydrometallurgical and other technical means can not only effectively extract tin resources, but also simultaneously recover other valuable metals to achieve efficient and comprehensive utilization of resources. The Chinese patent (CN108950222A) discloses a method for mineralizing and solidifying arsenic in high-arsenic tin smoke to recover tin. The specific operation is to classify the tin smoke after ultrasonic pretreatment, oxygen pressure leaching the ultrafine smoke obtained by classification, and catalytic oxidation of the leachate. Then, the mineralization solid arsenic reaction is carried out under the action of ultrasonic / pressurized coupling to obtain solid arsenic minerals; the coarse smoke obtained by classification and the washed leaching slag are returned to the conventional tin smelting production process for metallic tin recovery. A Chinese patent (CN115786717A) discloses a method for separating and recycling tin and zinc from electric furnace tin smelting dust. The specific operation is to wash the tin dust with water to remove chlorine and then leaching it under oxygen pressure. The leaching liquid is zinc sulfate solution. The zinc sulfate solution is returned to leaching and enriching zinc. The leaching residue is washed with water to obtain tin concentrate. The zinc enriched solution is precipitated with sodium salt. The residue is filtered and used as zinc raw material. Although the above two methods can achieve efficient recovery of tin in tin dust, the recovered tin is only used as primary smelting raw material, and the product added value is low. Summary of the invention

[0004] In view of the technical problems existing in the resource utilization of tin dust, the purpose of the present invention is to provide a method for efficiently recovering tin resources from the dust of a tin fuming furnace and preparing stannous sulfate. The method selectively leaches the tin therein by a wet method and removes impurity elements in the tin dust through a series of impurity removal reactions to prepare a high-purity stannous sulfate product, thereby providing a new way for the resource utilization of the dust of a tin fuming furnace. Compared with traditional processes, the method has the advantages of simplified process flow, low energy consumption, and environmental friendliness.

[0005] In order to achieve the above technical objectives, the present invention provides a method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate. The method comprises the following steps: 2 O 2 -H 2 SO 4 The mixed solution is subjected to oxidation leaching at 60-80°C, and the obtained leaching solution is subjected to reduction, impurity removal, and concentrated crystallization to obtain a stannous sulfate product; the H 2 O 2 -H 2 SO 4 H in the mixed solution 2 SO 4 The concentration of H 2 O 2 The concentration is 0.1~1 mol / L.

[0006] The key to the technical solution of the present invention is: according to the composition characteristics of tin minerals in the smoke of tin fuming furnace, H 2 O 2 -H 2 SO 4 The mixed solution is oxidized and leached, and the main component of SnS in the tin fuming furnace dust is efficiently and selectively converted into stannous sulfate (SnSO 4 ), and at the same time, a small amount of tin oxide contained in the smoke of the tin fuming furnace is also converted into Sn 4+ Sn can be leached by adding an appropriate amount of reducing agent. 4+ Restore to Sn 2+ , ensuring the purity of stannous sulfate products. On this basis, a series of impurity removal processes are used to selectively remove impurity ions such as Zn, As, Fe, and Si, and concentrate and crystallize to obtain stannous sulfate products.

[0007] The technical solution of the present invention is to realize the efficient and selective conversion of SnS in the smoke of the tin fuming furnace into stannous sulfate, and it is necessary to strictly coordinate and control the H 2 O 2 and H 2 SO 4 concentration and leaching temperature, if H 2 SO 4 If the concentration of H is too low, SnS will be difficult to decompose. 2 SO 4 concentration can effectively promote the transformation of SnS to SnSO 4 conversion to ensure that SnS is fully dissolved and recovered. 2 SO 4 If the concentration is too high, it may cause Sn 2+ Further oxidation to generate Sn(SO4 ) 2 By-products such as H2O2 not only reduce the purity of the target product, but also increase the difficulty of subsequent separation and purification. 2 O 2 The concentration is not higher than 1 mol / L. By adding a small amount of H 2 O 2 , which can promote S 2- The oxidation of SnS can improve the leaching efficiency and effectively inhibit the H 2 The release of S reduces the generation of harmful gases and ensures the safety and environmental protection of the reaction process. 2 O 2 Too high a concentration will not only lead to excessive oxidation, but also may cause Sn ²+ Further oxidation to generate Sn(SO 4 ) 2 Byproducts such as tin sulfate are produced, thereby reducing the purity of the product. At the same time, the leaching temperature has an important influence on the selective conversion of SnS into SnSO 4 It is also very important to properly increase the temperature, which is conducive to the transformation of SnS to SnSO 4 The effective conversion ensures the full dissolution and recovery of tin, but the temperature is too high. 2 O 2 The stability of H 2 O 2 Rapid decomposition reduces the oxidation efficiency, which not only affects the reaction effect but also may increase the reaction cost. 2 SO 4 and H 2 O 2 The concentration and leaching temperature can realize the efficient and selective conversion of SnS in the tin fuming furnace dust into stannous sulfate.

[0008] As a preferred solution, the tin component in the tin fuming furnace dust exists in the form of SnS and tin oxide, and the total tin grade is 40% to 60%. The tin component in the tin fuming furnace dust mainly exists in the form of SnS, and also contains a small amount of tin oxide. Since the tin component in the tin fuming furnace dust mainly exists in the form of SnS, conventional acid leaching is difficult to achieve leaching of tin, and existing oxidation leaching is difficult to obtain Sn. 2+ .

[0009] As a preferred solution, the tin fuming furnace dust is pre-treated by grinding; the grinding particle size satisfies that the mass percentage of the particle size less than 200 mesh is 100%. The tin fuming furnace dust is ground to a particle size less than 200 mesh. The fine particles have a high specific surface area, which can significantly improve the contact efficiency of the solid-liquid reaction, accelerate the mass transfer and chemical reaction rate during the leaching process, thereby effectively optimizing the reaction kinetic conditions and improving the recovery efficiency of tin resources.

[0010] As a preferred solution, the liquid-to-solid ratio of the oxidative leaching is 4-10 mL:1 g, and the leaching time is 1-3 h.

[0011] As a preferred solution, tin powder and iron powder are used as reducing agents in the reduction process. Tin powder and iron powder can effectively reduce Sn 4+ Restore to Sn 2+ At the same time, no other impurity elements will be introduced during the reduction process, thus ensuring the purity and effect of the reaction. The amount of tin powder or iron powder is Sn 4+ All converted into Sn 2+ 1.5~2.0 times the theoretical molar amount of tin powder or iron powder required.

[0012] As a preferred solution, the impurity removal process includes hydrolysis precipitation to remove arsenic and iron, flocculation sedimentation to remove silicon, and extraction to remove zinc. Tin fuming furnace dust often contains impurities such as zinc, iron, arsenic and silicon. If they are not effectively removed, the purity and subsequent application performance of the stannous sulfate product will be affected.

[0013] As a preferred solution, the hydrolysis precipitation process of removing arsenic and iron is: first adjust the pH to 3-4, then slowly add ferrous salt and hydrogen peroxide, and let it settle. Adjusting the weakly acidic environment of pH to 3.0-4.0 can avoid Sn 2+ hydrolysis, and slowly adding FeSO 4 (measured according to the molar ratio of Fe to As of 2 to 4:1) and H 2 O 2 (According to H 2 O 2 and As element according to the molar ratio of 1.5~2.0:1), Fe 2+ Oxidized to Fe 3+ , while As 3+ Oxidized to As 5+ , while Fe 3+ Fe(OH) is easily generated at around pH=3.5 3 Colloid, adsorbs arsenic ions and forms co-precipitation with Fe.

[0014] As a preferred solution, the flocculation sedimentation process for removing silicon is as follows: adding polyacrylamide and stirring thoroughly, and then standing to settle. The concentration of polyacrylamide added is about 0.1 mg / L, and after adding, stirring rapidly, and then standing to allow silicon to form floccules for removal.

[0015] As a preferred solution, di(2-ethylhexyl)phosphoric acid is used as the zinc ion extractant in the process of extracting and removing zinc. Di(2-ethylhexyl)phosphoric acid (D2EHPA) is used as the extractant, which has a high 2+ The distribution coefficient of Sn is higher.2+ There is almost no extraction, so deep removal of zinc can be achieved.

[0016] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0017] 1) The present invention utilizes an oxidative leaching method to treat tin fuming furnace dust and simultaneously prepare stannous sulfate, which not only realizes the efficient recovery of tin resources in the tin fuming furnace dust, but also successfully prepares a stannous sulfate product with high added value, providing a new way for the resource utilization of tin fuming furnace dust.

[0018] 2) The present invention makes full use of the conversion characteristics of SnS in an acidic oxidizing environment and precisely controls the H 2 O 2 and H 2 SO 4 The concentration and reaction temperature enable SnS to be directly and selectively converted into SnSO in an acidic oxidizing environment. 4 Then, by adding an appropriate amount of reducing agent, a small amount of Sn 4+ Restore to Sn 2+ And by regulating the chemical environment of the solution, impurity ions such as Zn, As, Fe, and Si are effectively removed to prepare a stannous sulfate product with higher purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD diagram of the smoke raw material of the fuming furnace in Example 1. DETAILED DESCRIPTION

[0020] The following examples are intended to further illustrate the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0021] The following specific examples and comparative examples use a certain factory fuming furnace dust, the metal Sn content of which is 50.5 wt.%, S content is 11.2 wt.%, O content is 7.4 wt.%, Zn content is 5.0 wt.%, Fe content is 2.7 wt.%, Si content is 1.2 wt.%, As content is 0.8 wt.%, wherein the molar ratio of SnS / SnO 2 =4.62.

[0022] Comparative Example 1

[0023] Compared with Example 1, the only difference is that the oxidation leaching adopts 1 mol / LH 2 O 2 and 1mol / LH 2 SO 4 of mixed solution.

[0024] Due to the low sulfuric acid concentration in the acid leaching process, the leaching rate may decrease.

[0025] Analysis of the experimental results showed that the recovery rate of metal Sn was 92.3%, and the SnSO 4 The content is 99.1 wt.%. Although SnSO 4 The product purity is high, but the recovery rate of tin is relatively low, which may be related to the + Insufficient concentration. + Low concentration will lead to incomplete reaction, affect the dissolution process of Sn, and thus reduce the leaching rate.

[0026] Comparative Example 2

[0027] Compared with Example 1, the only difference is that the oxidation leaching temperature is 25°C.

[0028] Since the temperature during the acid leaching process is too low, the leaching rate may decrease.

[0029] Analysis of the experimental results shows that the recovery rate of metal Sn is 93.5%, and the SnSO in the product is 4 The content is 99.1 wt.%. Although SnSO 4 The product purity is high, but the recovery rate of tin is relatively low, which may be related to the lower reaction temperature. The lower temperature may lead to limited dissolution kinetics of Sn, making the reaction incomplete and thus reducing the leaching rate.

[0030] Comparative Example 3

[0031] Compared with Example 1, the only difference is that the oxidation leaching adopts 3 mol / L H 2 O 2 and 5mol / LH 2 SO 4 of mixed solution.

[0032] Due to the acid leaching process, 2 O 2 Too high a concentration will further promote Sn 2+ Oxidation, the molar ratio of Sn in the leaching solution 2+ / Sn 4+ =2.54, indicating that there is more Sn 2+ Oxidized to Sn 4+ .

[0033] Analysis of the experimental results showed that the recovery rate of metal Sn was 99.2%, and the SnSO 4 The content was 98.6 wt.%. Although the recovery rate of tin was high, the purity of the product failed to meet the national standard. This may be due to the fact that H 2 O 2 The concentration is too high, resulting in a large amount of Sn 2+ Oxidized to Sn4+ Although a reducing agent was added later for adjustment, it still had a certain impact on the purity of the final product.

[0034] Example 1

[0035] 10g of fuming furnace dust after uniform grinding (the mass percentage of particle size less than 200 mesh is 100%) was placed in 1mol / L H 2 O 2 and 4mol / LH 2 SO 4 The mixed solution was oxidized and leached at 80 °C for 2 h with a liquid-to-solid ratio of 5 mL / 1 g, so that SnS was directly converted into SnSO in an acidic oxidizing environment. 4 , and the molar ratio of Sn in the leachate 2+ / Sn 4+ =4.61, indicating that Sn 2+ Almost no oxidation was observed. By adding 1.5 times the theoretical molar amount of reducing agent iron powder, Sn 4+ Restore to Sn 2+ To ensure the purity of the stannous sulfate product; then remove impurities, first add NaOH to adjust the pH to 3.5, and then slowly add FeSO 4 (Fe:As molar ratio 3:1) and industrial hydrogen peroxide (H 2 O 2 The amount of As is 1.5 times the molar amount of As), and the solution was allowed to stand for 2 hours to allow the iron salt in the solution to generate Fe(OH) 3 Colloid, and adsorb As to form a coprecipitate, and filter and separate the precipitate. Then add polyacrylamide (0.1 mg / L) to the solution and stir rapidly, and then let the solution stand for 2 hours to remove the silicon by forming floccules. Then add D2EHPA (di(2-ethylhexyl)phosphoric acid) (measured at 1.5 times the molar amount of Zn²⁺) to the solution and adjust the pH to 3 and stir, let it stand for 30 minutes, separate the loaded organic phase and the raffinate, and concentrate the raffinate to obtain SnSO 4 , realizing the recycling of tin resources.

[0036] The experimental results were analyzed: the recovery rate of metal Sn was 99.1%, and the SnSO 4 The content is 99.4wt.%. The recovery rate of tin is high, and the purity of the product meets the national standards, indicating that the process conditions are optimized reasonably and the reaction process is well controlled.

[0037] Example 2

[0038] 10g of fuming furnace dust after uniform grinding (the mass percentage of particle size less than 200 mesh is 100%) was placed in 0.9mol / LH 2 O2 and 5mol / LH 2 SO 4 The mixed solution was oxidized and leached at 70 °C for 2.5 hours with a liquid-to-solid ratio of 5 mL / 1 g, so that SnS was directly converted into SnSO in an acidic oxidizing environment. 4 , and the molar ratio of Sn in the leachate 2+ / Sn 4+ =4.60, indicating that Sn 2+ Almost no oxidation was observed. By adding 2 times the theoretical molar amount of reducing agent iron powder, Sn 4+ Restore to Sn 2+ To ensure the purity of the stannous sulfate product; then remove impurities, first add NaOH to adjust the pH to 3.5, and then slowly add FeSO 4 (Fe:As molar ratio 3:1) and industrial hydrogen peroxide (H 2 O 2 The amount of As is 1.5 times the molar amount of As), and the solution was allowed to stand for 2 hours to allow the iron salt in the solution to generate Fe(OH) 3 Colloid, and adsorb As to form a coprecipitate, and filter and separate the precipitate. Then add polyacrylamide (0.1 mg / L) to the solution and stir rapidly, and then let the solution stand for 2 hours to remove the silicon by forming floccules. Then add D2EHPA (di(2-ethylhexyl)phosphoric acid) (measured at 1.5 times the molar amount of Zn²⁺) to the solution and adjust the pH to 3 and stir, let it stand for 30 minutes, separate the loaded organic phase and the raffinate, and concentrate the raffinate to obtain SnSO 4 , realizing the recycling of tin resources.

[0039] The experimental results were analyzed: the recovery rate of metal Sn was 99.4%, and the SnSO 4 The content is 99.4wt.%. The recovery rate of tin is high, and the purity of the product meets the national standards, indicating that the process conditions are optimized reasonably and the reaction process is well controlled.

[0040] Example 3

[0041] 10g of fuming furnace dust after uniform grinding (the mass percentage of particles less than 200 mesh is 100%) is placed in 0.8mol / L H 2 O 4 and 6mol / LH 2 In the mixed solution of SO4, the liquid-to-solid ratio was 5 mL / 1 g, and oxidation leaching was carried out at 60 °C for 3 hours, so that SnS was directly converted into SnSO in an acidic oxidizing environment. 4 , and the molar ratio of Sn in the leachate 2+ / Sn 4+ =4.60, indicating that Sn 2+Almost no oxidation was observed. By adding 1.5 times the theoretical molar amount of reducing agent iron powder, Sn 4+ Restore to Sn 2 + To ensure the purity of the stannous sulfate product; then remove impurities, first add NaOH to adjust the pH to 3.5, and then slowly add FeSO 4 (Fe:As molar ratio 3:1) and industrial hydrogen peroxide (H 2 O 2 The amount of As is 1.5 times the molar amount of As), and the solution was allowed to stand for 2 hours to allow the iron salt in the solution to generate Fe(OH) 3 Colloid, and adsorb As to form a coprecipitate, and filter and separate the precipitate. Then add polyacrylamide (0.1 mg / L) to the solution and stir rapidly, and then let the solution stand for 2 hours to remove the silicon by forming floccules. Then add D2EHPA (di(2-ethylhexyl)phosphoric acid) (measured at 1.5 times the molar amount of Zn²⁺) to the solution and adjust the pH to 3 and stir, let it stand for 30 minutes, separate the loaded organic phase and the raffinate, and concentrate the raffinate to obtain SnSO 4 , realizing the recycling of tin resources.

[0042] The experimental results were analyzed and the recovery rate of metal Sn was 99.4%. 4 The content is 99.4wt.%. The recovery rate of tin is high, and the purity of the product meets the national standards, indicating that the process conditions are optimized reasonably and the reaction process is well controlled.

Claims

1. A method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate, characterized in that: The smoke from the tin fuming furnace is oxidized and leached at 60-80°C using a H2O2-H2SO4 mixed solution, and the obtained leaching solution is reduced, impurity-removed, concentrated and crystallized to obtain a stannous sulfate product; the concentration of H2SO4 in the H2O2-H2SO4 mixed solution is 4-6 mol / L, and the concentration of H2O2 is 0.1-1 mol / L.

2. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 1, characterized in that: The tin component in the tin fuming furnace dust exists in the form of SnS and tin oxide, and the total tin grade is 40% to 60%.

3. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 1 or 2, characterized in that: The smoke from the tin fuming furnace is pre-treated by grinding; the grinding particle size satisfies that the mass percentage of the particle size less than 200 meshes reaches 100%.

4. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 1, characterized in that: The liquid-to-solid ratio of the oxidation leaching is 4-10 mL:1 g, and the leaching time is 1-3 h.

5. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 1, characterized in that: In the reduction process, tin powder and iron powder are used as reducing agents.

6. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 1, characterized in that: The impurity removal process includes removing arsenic and iron by hydrolysis precipitation, removing silicon by flocculation sedimentation, and removing zinc by extraction.

7. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 6, characterized in that: The process of removing arsenic and iron by hydrolysis precipitation is: first adjust the pH to 3-4, then slowly add ferrous salt and hydrogen peroxide, and let it stand for sedimentation.

8. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 6, characterized in that: The process of flocculation sedimentation to remove silicon is as follows: adding polyacrylamide and stirring evenly, and then standing to settle.

9. The method for efficiently recovering tin resources from tin fuming furnace dust and preparing stannous sulfate according to claim 6, characterized in that: In the process of extracting and removing zinc, di(2-ethylhexyl)phosphoric acid is used as a zinc ion extractant.

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