Method for preparing refined tin by recovering stannous chloride industrial waste through combination of wet process and pyrogenic process

Abstract

The invention discloses a method for preparing refined tin by recovering stannous chloride industrial waste through combination of a wet process and a pyrogenic process. The method comprises the steps of ball milling, aeration pre-oxidation, liquid caustic soda addition for tin precipitation, filter pressing, reduction smelting and sodium chloride byproduct recovery. According to the method, a low-cost method that aeration replaces hydrogen peroxide is adopted to oxidize Sn < 2 + > into Sn < 4 + >, chlorine is completely dissolved in water, then an alkaline material is added to completely precipitate free tin, finally, slag and liquid are separated, tin is distributed in slag in a concentrated mode, chlorine is dissolved in water liquid, the purpose of separating chlorine is achieved, and recovery of tin metal is not affected; the process is simple, the industrial production cost is low, the utilization rate of the metal resource tin is increased, the environmental pollution caused by the stannous chloride waste is improved, and the method is worthy of popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of wet-process combined pyrometallurgy, and in particular to a method for preparing refined tin by recycling stannous chloride industrial waste through wet-process combined pyrometallurgy. Background Art

[0002] Tin metal has high value and is mainly used in electronic products, steel manufacturing, aerospace and other fields. In electronic products, tin is often used as solder. Due to its non-toxicity, low melting point and stable chemical properties, it is widely used in electronics, electrical appliances, chemical industry and other fields. Stannous chloride can be used as a reaction synthesis catalyst in chemical production. It is widely used in the chemical and organic synthesis industries and is used in many chemical reactions, such as reduction and hydrogenation reactions. However, the industrial waste generated after the catalytic failure has pain points such as difficult treatment, low recovery rate and serious pollution.

[0003] Stannous chloride waste contains different amounts of tin metal. As a valuable metal, if tin metal cannot be efficiently recycled, it will not only cause waste of resources, but also cause environmental damage caused by the loss of tin metal.

[0004] Stannous chloride industrial waste is generally divided into two forms, hard block and soft mud, due to its storage process and time. The tin content ranges from about 5% to 40%. It is dissolved in water and hydrolyzed to produce HCl. Its aqueous solution is strongly acidic, and most of the tin metal is free in the water as Sn2+. If it is directly calcined by fire method, a considerable part of the tin metal will sublime and volatilize, and the purpose of recovering valuable metals cannot be achieved.

[0005] Because tin is an amphoteric compound, the acidic liquid after stannous chloride is dissolved in water is directly neutralized and precipitated with alkaline solution. While Sn(OH)2 precipitates, soluble Na2SnO2 will also be generated, which cannot achieve the purpose of complete precipitation and recovery. If Sn2+ is first oxidized to Sn4+ with oxides and then precipitated with alkaline solution, although the tin recovery rate can be improved, the oxidation recovery cost is too high and cannot be fully promoted and applied.

[0006] The effective recycling and treatment of stannous chloride waste by combining wet and pyrolysis methods can not only reduce industrial production costs, but also improve the utilization rate of metal resources, leading industrial production to form a virtuous development cycle. Summary of the invention

[0007] In order to solve the problem that if the tin metal in the existing stannous chloride waste cannot be efficiently recovered, it will not only cause waste of resources, but also cause environmental damage caused by the loss of tin metal. The present invention provides a method for recovering stannous chloride industrial waste by wet method combined with pyrolysis to prepare refined tin. The method adopts a low-cost method to recover Sn 2+ Partially oxidized to Sn 4+, so that the chlorine is completely dissolved in the water, and then alkaline materials are added to completely precipitate the free tin. Finally, the slag and liquid are separated. The tin is concentrated in the slag and the chlorine is dissolved in the water, achieving the purpose of separating the chlorine without affecting the recovery of tin metal; the filter residue is transferred to a vacuum reduction smelting furnace for reduction smelting to extract a refined tin product with a content of ≥95%.

[0008] To achieve the above object, the present invention provides the following technical solutions: A method for preparing refined tin by recovering stannous chloride industrial waste by wet method combined with pyrolysis, characterized in that it comprises the following steps: S1. Ball milling: soak the hard block stannous chloride industrial waste with water and then ball mill it to a particle size of ≤50 mesh. This step can be omitted for the soft mud stannous chloride industrial waste; S2, aeration pre-oxidation: add the stannous chloride industrial waste or the soft sludge stannous chloride industrial waste obtained after ball milling in step S1 into a stirring barrel, then add 4 to 10 times the weight of the stannous chloride industrial waste water into the stirring barrel, mix, stir to dissolve, and turn on the air compressor to pass compressed air into the feed liquid for aeration, set the temperature in the stirring barrel to 50 to 60° C., continue stirring for 30 minutes, and obtain a feed liquid with a pH less than 0.5 to 1; S3, adding liquid alkali to precipitate tin: add 30% liquid alkali to the stirring barrel to adjust the liquid pH value to pH8-9, continue aeration and stirring, during the reaction of the feed liquid, the pH will show a downward trend, and the liquid alkali is continuously added to maintain the pH of the feed liquid at pH8-9 until the pH of the feed liquid stabilizes at pH8-9 without change, and SnO and SnO2 precipitation liquid are obtained; S4, filter pressing: the precipitate obtained in step S3 is subjected to filter pressing to obtain a filtrate and a filter residue; S5, reduction smelting: the filter residue obtained in step S4 is crude tin, and the crude tin is transferred into a vacuum reduction smelting furnace for reduction smelting to extract a refined tin product with a content of ≥95%; S6, recovering the sodium chloride byproduct; the filtrate obtained in step S4 is sodium chloride brine, activated carbon is added to the sodium chloride brine, stirred for adsorption and decolorization, and then finely filtered to obtain a clear filtrate, dilute hydrochloric acid is added to the clear filtrate to adjust the pH value to pH 7-PH 8, and then the clear filtrate is evaporated to obtain a crude sodium chloride salt byproduct, and the evaporated distilled water is returned to step S1 or S2 for recycling.

[0009] As a further improvement of the present technology, in step S2, an aeration pipe is provided on the mixing barrel, and the aeration pipe includes a vent pipe and an aeration pipe. The vent pipe is designed to be annular and is arranged above the mixing barrel. An air inlet is provided on the upper side wall of the vent pipe and is connected to an air outlet of an air compressor. A plurality of aeration pipes are provided on the lower side wall of the vent pipe. The plurality of aeration pipes extend into the mixing barrel and are evenly distributed along the circumference of the inner wall of the mixing barrel. The outer side wall of the aeration pipe is fixedly connected to the inner side wall of the mixing barrel by a plurality of vertically evenly distributed support rods. The lower end of the aeration pipe is inserted into the bottom of the mixing barrel, and the aeration port at the lower end is designed to be a 45° oblique opening, and the 45° oblique opening faces the center of the mixing barrel.

[0010] As a further improvement of the present technology, in step S2, a steam inlet is further provided on the upper side wall of the stirring barrel, the lower end of the steam inlet extends into the liquid, and the upper end of the steam inlet is connected to a steam pipe, which is used to pass steam into the stirring barrel to heat the liquid; a thermocouple is inserted on the outer side wall of the stirring barrel, which is used to detect the temperature in the stirring barrel, and when the temperature in the stirring barrel reaches 50-60°C, the steam is stopped.

[0011] During the reaction, the temperature in the stirring barrel is maintained above 50°C. When it is lower than 50°C, steam needs to be introduced again to keep the temperature in the stirring barrel above 50°C.

[0012] As a further improvement of the present technology, the reaction process in step S3 is 150 min, and Sn in the supernatant is ≤0.2 g / L after the reaction is completed.

[0013] As a further improvement of the present technology, the crude tin slag in step S5 needs to be transferred to a rotary kiln for drying and then crushed to a particle size of ≤100 mesh before being transferred to the reduction smelting furnace, and then coke with a particle size of 100-200 mesh is added for mixing, and then reduced and smelted at 1500°C after entering the reduction smelting furnace.

[0014] As a further improvement of the present technology, the amount of activated carbon added in step S6 is 1 / 2000 to 1 / 1000 of the mass of the filtrate.

[0015] In addition to chlorine and tin, stannous chloride industrial waste often contains some other trace metal elements, such as lead, calcium, and nickel, with a general content of less than 1%. If stannous chloride is used as a catalyst source for organic synthesis, it also contains a small amount of organic matter. Industrial stannous chloride is easily soluble in water. After aeration pre-oxidation, liquid alkali is added to adjust the pH of the solution to convert it into SnO and SnO2 precipitation. The chemical reactions involved are: SnCl2+H2O=SnO↓+2HCl; SnCl2+H2O2=SnO2↓+2HCl; SnCl2+4NaOH=Na2SnO2+2NaCl+2H2O; Na2SnO2+H2O2=Na2SnO3+H2O; Na2SnO2+2HCl=SnO↓+H2O+2NaCl; Na2SnO3+4HCl=SnO2↓+2H2O+2NaCl; SnO+H2O2=SnO2↓+H2O The comprehensive reaction equation can be expressed as: 2SnCl2+4NaOH+H2O2=SnO↓+SnO2↓+3H2O+4NaCl The present invention proceeds from the principle of stannous chloride oxidation reaction and recovers stannous chloride industrial waste by a relatively low-cost wet method. Tin can be deposited in slag in the form of precipitate, while chlorine is dissolved in water. After the slag and liquid are separated, the tin slag with low chlorine content can be directly fed into a vacuum reduction smelting furnace to extract a refined tin product with a content of ≥95%.

[0016] The trace heavy metals in the stannous chloride waste will enter the vacuum reduction smelting furnace together with the tin slag. After reduction smelting at 1500℃, the melting point of the elemental tin metal obtained by reduction smelting is 232℃. The elemental liquid tin metal flows out of the reduction smelting furnace to obtain elemental liquid tin with a content of ≥95%, thereby separating the trace heavy metals from the liquid tin metal.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses wet aeration pre-oxidation, then adds liquid alkali to precipitate tin, recovers by filter pressing, and then obtains a refined tin product by pyrometallurgical reduction smelting. The tin recovery rate in the process is as high as over 97.8%, water can be recycled, and the amount of waste slag generated is small. It is a closed-loop process that can be virtuously circulated, has a simple process, and has low industrial production costs. It improves the utilization rate of the metal resource tin and improves the environmental pollution caused by stannous chloride waste, and is worthy of promotion and application.

[0018] 1. The present invention uses aeration oxidation to replace the hydrogen peroxide used in the prior art to treat Sn 2+ Oxidation saves the cost of auxiliary materials; 2. The present invention uses tin precipitation and tin oxidation to carry out simultaneously, which saves the cost of auxiliary materials and simplifies the production operation process; 3. The present invention simultaneously completes the heavy metal removal operation during the process of recovering stannous chloride waste, and the filtrate only needs simple pretreatment to directly evaporate the salt, and the distilled water is returned to steps 1 and 2 for recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of the external structure of the mixing barrel used in the present invention; Figure 3This is a schematic diagram of the internal cross-sectional structure of the stirring barrel used in the present invention.

[0020] In the figure: 1. mixing barrel, 101. steam inlet, 2. aeration pipe, 201. ventilation pipe, 202. air inlet, 203. aeration pipe, 2031. aeration port, 204. support rod, 3. thermocouple. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The recovered stannous chloride industrial waste (content: Sn 44.87%, Cl 23.82%, Ni 0.11%, Zn 0.023%, Cu 0.03%, Mn 0.004%, Pb 0.083%, Ca 0.025%, Mg 0.016%) has a hard block appearance. The above stannous chloride industrial waste is ball-milled to a particle size of ≤50 mesh, and then put into a mixing barrel. Then, clean water 6 times the weight of the stannous chloride industrial waste is added to the mixing barrel for leaching and stirring. At the same time, the air compressor is turned on for aeration, and steam is introduced into the mixing barrel to heat the barrel to 55°C. Preheating can accelerate the dissolution of the stannous chloride industrial waste. The stirring time is 30 minutes, and the pH of the liquid is <0.5.

[0023] Then add 30% liquid alkali to neutralize the liquid, adjust the pH to about 8.5, continue aeration and stirring, the pH of the liquid will continue to decrease, and the liquid alkali is continuously added to maintain the pH of the liquid between 8 and 9 until the pH of the liquid stabilizes. In this process, tin oxidation and tin precipitation are carried out simultaneously, about 150 minutes, and the amount of 30% liquid alkali consumed is equal to the weight of the input stannous chloride industrial waste.

[0024] The supernatant was analyzed: Sn: ≤0.2g / L, Cl ≥38g / L, indicating that tin was basically precipitated in the slag, and Cl was completely dissolved in the water, and the material could be discharged and filtered.

[0025] The filtrate after pressure filtration is decolorized by activated carbon at a ratio of 1 / 2000 of the filtrate weight to remove organic matter in the filtrate. After a fine filtration, a sodium chloride crude brine (containing 26.3 g / L Na, 40.6 g / L Cl, 0.005 g / L Ni, 0.009 g / L Zn, 0.001 g / L Cu, 0.001 g / L Pb, 0.001 g / L Ca, 0.03 g / L Mg) is obtained. An appropriate amount of dilute hydrochloric acid is added to the sodium chloride crude brine to adjust the pH of the brine to 7-8, and the salt is evaporated to obtain a sodium chloride salt by-product. The distilled water is returned to the mixing barrel for recycling.

[0026] The filter residue after filtration is crude tin residue, which has a weight loss of about 37% (content: Sn 70.45%, Cl 1.22%, Na 1.18%, Ni0.15%, Zn 0.025%, Cu 0.04%, Mn 0.005%, Pb 0.085%, Ca 0.011%, Mg 0.008%). The crude tin residue is dried in a rotary kiln and crushed to a particle size of 120 mesh. It is mixed with 100-200 mesh coke and then put into a reduction smelting furnace for reduction smelting at 1500℃. The melting point of the elemental tin metal obtained by reduction smelting is 232℃. The liquid tin metal flows out of the smelting furnace to obtain a refined tin product with a content of 98.5%. At the same time, the separation of other trace heavy metals is realized.

[0027] Through the above wet method combined with fire method to treat stannous chloride industrial waste, the tin recovery rate reaches 99.1%, and high-purity refined tin products are obtained.

[0028] The recovered stannous chloride industrial waste (content: Sn 5.92%, Cl 10.46%, Ni 0.083%, Zn 0.013%, Cu 0.02%, Mn 0.006%, Pb 0.056%, Ca 0.015%, Mg 0.009%) has a sludge-like appearance. The sludge-like stannous chloride industrial waste is directly put into a mixing barrel, and then clean water 4 times the weight of the stannous chloride industrial waste is added to the mixing barrel for leaching and stirring. At the same time, the air compressor is turned on for aeration, and steam is introduced into the mixing barrel to heat the barrel to 54°C to accelerate the dissolution of the stannous chloride industrial waste. The stirring time is 30 minutes, and the pH of the liquid is <1.0.

[0029] Then add 30% liquid alkali to neutralize the liquid, adjust the pH to about 8.5, continue aeration and stirring, the pH of the liquid will continue to decrease, and the liquid alkali is continuously added to maintain the pH of the liquid between 8 and 9 until the pH of the liquid stabilizes. In this process, tin oxidation and tin precipitation are carried out simultaneously, about 150 minutes, and the amount of 30% liquid alkali consumed is equal to 1 / 3 of the weight of the input stannous chloride industrial waste.

[0030] The supernatant was analyzed: Sn: ≤0.2g / L, Cl ≥25g / L, indicating that tin was basically precipitated in the slag, and Cl was completely dissolved in the water, and the material could be discharged and filtered.

[0031] The filtrate after pressure filtration is decolorized by adsorption with activated carbon in a proportion of 1 / 1000 of the weight of the filtrate to remove organic matter in the filtrate, and then finely filtered to obtain sodium chloride crude brine (content: Na 17.6g / L, Cl 27.5g / L, Ni 0.003g / L, Zn 0.004g / L, Cu 0.001g / L, Pb 0.001g / L, Ca 0.02g / L, Mg 0.001g / L). An appropriate amount of dilute hydrochloric acid is added to the sodium chloride crude brine to adjust the pH of the brine to pH 7-8, and the salt is evaporated to obtain sodium chloride salt by-product, and the distilled water is returned to the mixing barrel for recycling.

[0032] The residue after filtration is crude tin residue, which has a weight loss of about 90% (content: Sn 61.38%, Cl 1.85%, Na 1.35%, Ni0.1%, Zn 0.03%, Cu 0.04%, Mn 0.005%, Pb 0.09%, Ca 0.04%, Mg 0.008%). The crude tin residue is dried in a rotary kiln and crushed to a particle size of 180 mesh. It is mixed with 100-200 mesh coke and then put into a reduction smelting furnace for reduction smelting at 1500℃. The melting point of the elemental tin metal obtained by reduction smelting is 232℃. The liquid tin metal flows out of the smelting furnace to obtain a refined tin product with a content of 97.2%. At the same time, the separation of other trace heavy metals is realized.

[0033] Through the above wet method combined with fire method to treat stannous chloride industrial waste, the tin recovery rate reaches 97.8%, and high-purity refined tin products are obtained.

[0034] The recovered hard lump stannous chloride industrial waste (content: Sn 48.35%, Cl 29.34%, Ni 0.15%, Zn0.018%, Cu 0.05%, Mn 0.006%, Pb 0.065%, Ca 0.021%, Mg 0.012%) was ball-milled to a material size of ≤50 mesh, and then mixed with the recovered soft sludge stannous chloride industrial waste (content: Sn 7.44%, Cl 6.62%, Ni 0.055%, Zn0.012%, Cu 0.01%, Mn 0.008%, Pb 0.062%, Ca 0.013%, Mg 0.005%), and the mixing ratio was hard lump: soft sludge = 4:1. Put the soft and hard stannous chloride industrial waste into a mixing barrel, then add clean water 5 times the total weight of the stannous chloride industrial waste into the mixing barrel for leaching and stirring, turn on the air compressor for aeration at the same time, pass steam into the mixing barrel to heat it to 58°C, stir for 30 minutes, and the PH value of the liquid is <0.5.

[0035] Then add 30% liquid alkali to neutralize the feed liquid, adjust the pH to about 8.5, continue aeration and stirring, at this time the feed liquid pH will continue to decrease, and the liquid alkali is continuously added to maintain the feed liquid pH between 8 and 9 until the feed liquid pH stabilizes. In this process, tin oxidation and tin precipitation are carried out simultaneously, about 150 minutes, and the amount of 30% liquid alkali consumed is equal to 3 / 4 of the weight of the input stannous chloride industrial waste.

[0036] The supernatant was analyzed: Sn: ≤0.2g / L, Cl ≥48g / L, indicating that tin was basically precipitated in the slag, and Cl was completely dissolved in the water, and the material could be discharged and filtered.

[0037] The filtrate after pressure filtration is decolorized by adsorption with activated carbon in a proportion of 1 / 2000 of the weight of the filtrate to remove organic matter in the filtrate. After a fine filtration, a sodium chloride crude brine (content: Na 32.3g / L, Cl 50.2g / L, Ni 0.002g / L, Zn 0.003g / L, Cu 0.001g / L, Pb 0.001g / L, Ca 0.025g / L, Mg 0.001g / L) is obtained. An appropriate amount of dilute hydrochloric acid is added to the sodium chloride crude brine to adjust the pH of the brine to pH 7-8, and the salt is evaporated to obtain sodium chloride salt by-product, and the distilled water is returned to the stirring barrel for recycling.

[0038] The filter residue after filtration is crude tin residue, with a weight loss of about 42% (content: Sn 67.52%, Cl 1.25%, Na 1.19%, Ni0.1%, Zn 0.02%, Cu 0.03%, Mn 0.003%, Pb 0.07%, Ca 0.05%, Mg 0.004%). The crude tin residue is dried in a rotary kiln and crushed to a particle size of 150 mesh. Coke is added and mixed into a reduction smelting furnace. The reduction smelting is carried out at 1500℃. The melting point of elemental tin metal is 232℃. The liquid tin metal flows out of the smelting furnace to obtain a refined tin product with a content of 98.7%. At the same time, the separation of other trace heavy metals is realized.

[0039] Through the above wet method combined with fire method to treat stannous chloride industrial waste, the tin recovery rate reaches 98.9%, and high-purity refined tin products are obtained.

[0040] As a preference, Figure 2 , Figure 3As shown, the mixing barrel used in the above embodiment is provided with an aeration pipe 2, and the aeration pipe 2 includes a vent pipe 201 and an aeration pipe 203. The vent pipe 201 is set in a ring shape and is arranged above the mixing barrel 1. An air inlet 201 is provided on the upper side wall of the vent pipe 201 to be connected with the air outlet of the air compressor. Four aeration pipes 203 are provided on the lower side wall of the vent pipe 201. The four aeration pipes 203 extend into the mixing barrel 1 and are evenly distributed along the circumference of the inner wall of the mixing barrel 1. The outer wall of the aeration pipe 203 is fixedly connected to the inner wall of the mixing barrel 1 through three vertically evenly distributed support rods 204. The lower end of the aeration pipe 203 is inserted into the bottom of the mixing barrel 1, and the aeration port 2031 at the lower end is set to a 45° bevel, and the 45° bevel faces the center of the mixing barrel 1.

[0041] The 45° inclined aeration port allows compressed air to come out from an inclined angle to agitate the liquid, thereby enhancing the mixed oxidation effect with the liquid.

[0042] A steam inlet 101 is also provided on the upper side wall of the mixing barrel 1, the lower end of the steam inlet 101 extends into the feed liquid, and the upper end of the steam inlet 101 is connected to a steam pipe, which is used to introduce steam into the mixing barrel 1 to preheat the feed liquid to accelerate the dissolution of stannous chloride industrial waste; a thermocouple 3 is inserted on the outer side wall of the mixing barrel 1 to detect the temperature in the mixing barrel 1. When the temperature in the mixing barrel 1 reaches above 50°C, the steam is stopped from being introduced. When the temperature in the mixing barrel is lower than 50°C, steam needs to be supplemented to maintain the temperature in the mixing barrel above 50°C.

[0043] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering stannous chloride industrial waste by wet method combined with pyrolysis to prepare refined tin, characterized in that: The following steps are involved: S1. Ball milling: soak the hard block stannous chloride industrial waste with water and then ball mill it to a particle size of ≤50 mesh. This step can be omitted for the soft mud stannous chloride industrial waste; S2, aeration pre-oxidation: add the stannous chloride industrial waste or the soft sludge stannous chloride industrial waste obtained after ball milling in step S1 into a stirring barrel, then add 4 to 10 times the weight of the stannous chloride industrial waste water into the stirring barrel, mix, stir to dissolve, and turn on the air compressor to pass compressed air into the feed liquid for aeration, set the temperature in the stirring barrel to 50 to 60° C., continue stirring for 30 minutes, and obtain a feed liquid with a pH less than 0.5 to 1; S3, adding liquid alkali to precipitate tin: add 30% liquid alkali to the stirring barrel to adjust the liquid pH value to pH8-9, continue aeration and stirring, during the reaction of the feed liquid, the pH will show a downward trend, and the liquid alkali is continuously added to maintain the pH of the feed liquid at pH8-9 until the pH of the feed liquid stabilizes at pH8-9 without change, and SnO and SnO2 precipitation liquid are obtained; S4, filter pressing: the precipitate obtained in step S3 is subjected to filter pressing to obtain a filtrate and a filter residue; S5, reduction smelting: the filter residue obtained in step S4 is crude tin, and the crude tin is transferred into a vacuum reduction smelting furnace for reduction smelting to extract a refined tin product with a content of ≥95%; S6, recovering the sodium chloride byproduct; the filtrate obtained in step S4 is sodium chloride brine, activated carbon is added to the sodium chloride brine, stirred for adsorption and decolorization, and then finely filtered to obtain a clear filtrate, dilute hydrochloric acid is added to the clear filtrate to adjust the pH value to pH 7-PH 8, and then the clear filtrate is evaporated to obtain a crude sodium chloride salt byproduct, and the evaporated distilled water is returned to step S1 or S2 for recycling.

2. The method for preparing refined tin by recovering stannous chloride industrial waste by a wet method combined with a pyroprocess according to claim 1, characterized in that: In step S2, an aeration pipe is provided on the mixing barrel, and the aeration pipe includes a vent pipe and an aeration pipe. The vent pipe is designed to be annular and is arranged above the mixing barrel. An air inlet is provided on the upper side wall of the vent pipe and is connected to the air outlet of the air compressor. A plurality of aeration pipes are provided on the lower side wall of the vent pipe. The plurality of aeration pipes extend into the mixing barrel and are evenly distributed along the circumference of the inner wall of the mixing barrel. The outer side wall of the aeration pipe is fixedly connected to the inner side wall of the mixing barrel by a plurality of vertically evenly distributed support rods. The lower end of the aeration pipe is inserted into the bottom of the mixing barrel, and the aeration port at the lower end is set to a 45° oblique opening, and the 45° oblique opening faces the center of the mixing barrel.

3. The method for preparing refined tin by recovering stannous chloride industrial waste by a wet method combined with a pyroprocess according to claim 1, characterized in that: In step S2, a steam inlet is further provided on the upper side wall of the stirring barrel, the lower end of the steam inlet extends into the liquid, and the upper end of the steam inlet is connected to a steam pipe, which is used to pass steam into the stirring barrel to heat the liquid; a thermocouple is inserted on the outer side wall of the stirring barrel, which is used to detect the temperature in the stirring barrel, and when the temperature in the stirring barrel reaches the set temperature, the steam is stopped from being passed.

4. The method for preparing refined tin by recovering stannous chloride industrial waste by a wet method combined with a pyroprocess according to claim 1, characterized in that: The reaction process in step S3 is 150 min, and Sn in the supernatant is ≤0.2 g / L after the reaction is completed.

5. The method for preparing refined tin by recovering stannous chloride industrial waste by a wet method combined with a pyroprocess according to claim 1, characterized in that: In step S5, the crude tin slag is dried in a rotary kiln and crushed to a particle size of ≤100 mesh before entering the reduction smelting furnace, and then coke with a particle size of 100-200 mesh is added and mixed, and then reduced and smelted at 1500° C. after entering the reduction smelting furnace.

6. The method for preparing refined tin by recovering stannous chloride industrial waste by a wet method combined with a pyroprocess according to claim 1, characterized in that: The amount of activated carbon added in step S6 is 1 / 2000 to 1 / 1000 of the mass of the filtrate.

Images