Method for preparing refined tin from industrial waste of stannous chloride by wet combined pyrogenic recovery

Abstract

The application discloses a method for preparing refined tin from stannous chloride industrial waste by a wet combined fire method, and the method comprises the following steps: ball milling, aeration pre-oxidation, tin precipitation by adding liquid alkali, pressure filtration, reduction smelting and recovery of sodium chloride by-products. 2+ partial oxidation into Sn 4+ The free tin is completely precipitated by adding alkaline materials, and finally, the slag and liquid are separated, the tin is concentrated in the slag, the chlorine is dissolved in the liquid, the purpose of separating chlorine is achieved, and the recovery of tin metal is not affected; the filtered slag is transferred into a vacuum reduction smelting furnace for reduction smelting, and the refined tin product with a content of greater than or equal to 95% is refined, and the heavy metal removal operation is completed, the process is simple, the industrial production cost is low, the utilization rate of metal resources tin is improved, the environmental pollution caused by the stannous chloride waste is improved, and the method is worthy of promotion and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy combined with pyrometallurgy, and particularly relates to a method for preparing refined tin by recovering stannous chloride industrial waste through hydrometallurgy combined with pyrometallurgy. BACKGROUND

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

[0003] The stannous chloride waste contains different amounts of tin metal. If the tin metal cannot be efficiently recovered, not only the resources will be wasted, but also the environment will be harmed due to the loss of tin metal.

[0004] The stannous chloride industrial waste is generally divided into hard block and soft mud shapes due to the storage process and time, and the tin content is from about 5% to 40%. The hydrolysis of the stannous chloride industrial waste produces HCl, and the aqueous solution is strongly acidic. Most of the tin metal is in the form of Sn2+ in water. If the stannous chloride industrial waste is directly calcined by the pyrometallurgical method, a considerable part of the tin metal will sublimate and volatilize, and the purpose of valuable metal recovery cannot be achieved.

[0005] Because tin is amphoteric, the acidic solution after the stannous chloride is dissolved in water is neutralized and precipitated by directly adding alkali. The Sn(OH)2 precipitate is generated at the same time, and the soluble Na2SnO2 is also generated, which cannot achieve the purpose of complete precipitation and recovery. If Sn2+ is first oxidized to Sn4+ by using an oxidant, and then precipitated by using an alkali, although the tin recovery rate can be improved, the cost of oxidation recovery is too high, and the method cannot be widely applied.

[0006] The technical means of combining the hydrometallurgical method with the pyrometallurgical method is used to effectively recover and treat the stannous chloride waste, which can not only reduce the industrial production cost, but also improve the utilization rate of metal resources and lead the industrial production to form a virtuous development cycle. SUMMARY

[0007] To solve the problem that the tin metal in the existing stannous chloride waste cannot be efficiently recovered, which not only causes the waste of resources, but also causes the environmental harm due to the loss of tin metal, the present application provides a method for preparing refined tin by recovering stannous chloride industrial waste through hydrometallurgy combined with pyrometallurgy. 2+ Sn2+ is partially oxidized to Sn4+ 4+The free tin is completely precipitated by adding the base material after the chlorine is completely dissolved in the water, and then the slag liquid is separated, the tin is concentrated in the slag, the chlorine is dissolved into the water liquid, the purpose of separating the chlorine is achieved, and the recovery of the tin metal is not affected; the filter residue is transferred into a vacuum reduction smelting furnace for reduction smelting, and a refined tin product with a content of ≥95% is refined.

[0008] To achieve the above object, the present application provides the following technical scheme:

[0009] A method for recycling stannous chloride industrial waste to prepare refined tin by a combination of wet process and fire process, characterized in that the method comprises the following steps:

[0010] S1, ball milling: the hard blocky stannous chloride industrial waste is soaked with water and then ball milled to a particle size of ≤50 mesh, and the soft muddy stannous chloride industrial waste omits this step;

[0011] S2, aeration pre-oxidation: the stannous chloride industrial waste obtained after the ball milling in step S1 or the soft muddy stannous chloride industrial waste is added into a stirring barrel, 4-10 times the weight of the stannous chloride industrial waste of water is added into the stirring barrel for mixing, stirring and dissolving are performed, a compressed air machine is started to introduce compressed air into the liquid for aeration, the temperature in the stirring barrel is set to 50-60℃, and the stirring is continuously performed for 30 min to obtain a liquid with a pH of less than 0.5-1;

[0012] S3, tin precipitation by adding liquid alkali: the liquid alkali with a concentration of 30% is added into the stirring barrel to adjust the pH of the liquid to pH 8-pH 9, the aeration and stirring are continuously performed, during the reaction process of the liquid, the pH shows a downward trend, the liquid alkali is continuously added to maintain the pH of the liquid at pH 8-pH 9, until the pH of the liquid is stable at pH 8-pH 9 without change, and a SnO and SnO2 precipitate liquid is obtained;

[0013] S4, pressure filtration: the precipitate liquid obtained in step S3 is subjected to pressure filtration to obtain a filtrate and a filter residue;

[0014] S5, reduction smelting: the filter residue obtained in step S4 is crude tin, which is transferred into a vacuum reduction smelting furnace for reduction smelting, and a refined tin product with a content of ≥95% is refined;

[0015] S6, recovery of sodium chloride byproduct; the filtrate obtained in step S4 is sodium chloride brine, activated carbon is added into the sodium chloride brine, the sodium chloride brine is stirred and adsorbed for decolorization, then the sodium chloride brine is refined to obtain a clear filtrate, dilute hydrochloric acid is added into the clear filtrate to adjust the pH to pH 7-pH 8, then the clear filtrate is evaporated to obtain a crude sodium chloride salt byproduct, and the distilled water evaporated is returned to step S1 or S2 for recycling.

[0016] As a further improvement of the present technology, the aeration pipeline is arranged on the upper side wall of the stirring barrel in step S2, the aeration pipeline comprises a ventilation pipe and aeration pipes, the ventilation pipe is arranged in a ring shape and above the stirring barrel, the upper side wall of the ventilation pipe is provided with an air inlet connected with the air outlet of the air compressor, and the lower side wall of the ventilation pipe is provided with a plurality of aeration pipes, the aeration pipes extend into the stirring barrel and are evenly distributed along the inner side wall of the stirring barrel, the outer side wall of the aeration pipe is fixedly connected with the inner side wall of the stirring barrel through a plurality of vertical supporting rods, the lower end of the aeration pipe is inserted into the bottom of the stirring barrel, the lower end aeration inlet is arranged in a 45° inclined opening, and the 45° inclined opening faces the center of the stirring barrel.

[0017] As a further improvement of the present technology, the stirring barrel is further provided with a steam inlet on the upper side wall in step S2, the lower end of the steam inlet extends into the liquid, the upper end of the steam inlet is connected with a steam pipeline, and the steam is introduced into the stirring barrel to heat the liquid; a thermocouple is arranged on the outer side wall of the stirring barrel to detect the temperature in the stirring barrel, and the steam is stopped when the temperature in the stirring barrel reaches 50-60℃.

[0018] The temperature in the stirring barrel is maintained above 50℃ during the reaction, and the steam needs to be introduced again when the temperature is below 50℃ to maintain the temperature in the stirring barrel above 50℃.

[0019] As a further improvement of the present technology, the reaction time is 150 min in step S3, and the Sn content in the supernatant after the reaction is completed is ≤0.2 g / L.

[0020] As a further improvement of the present technology, the crude tin residue is dried in a rotary kiln before being transferred into the reduction smelting furnace in step S5, and then crushed to a particle size ≤100 mesh, mixed with coke with a particle size of 100-200 mesh, and then introduced into the reduction smelting furnace for reduction smelting at 1500℃.

[0021] As a further improvement of the present technology, the amount of activated carbon added in step S6 is 1 / 2000-1 / 1000 of the mass of the filtrate.

[0022] In addition to chlorine and tin, industrial stannous chloride waste often contains some other trace metal elements such as lead, calcium and nickel, and the content is generally less than 1%. If stannous chloride is used as a catalyst for organic synthesis, there is also a small amount of organic matter. Industrial stannous chloride is easily soluble in water, and after pre-oxidation by aeration, liquid alkali is added to adjust the pH of the solution, which can convert it into SnO and SnO2 precipitates. The chemical reactions involved are:

[0023] SnCl2+H2O=SnO↓+2HCl;

[0024] SnCl2+H2O2=SnO2↓+2HCl;

[0025] SnCl2+4NaOH=Na2SnO2+2NaCl+2H2O;

[0026] Na2SnO2+H2O2=Na2SnO3+H2O;

[0027] Na2SnO2+2HCl=SnO↓+H2O+2NaCl;

[0028] Na2SnO3+4HCl=SnO2↓+2H2O+2NaCl;

[0029] SnO+H2O2=SnO2↓+H2O

[0030] The comprehensive reaction equation can be expressed as:

[0031] 2SnCl2+4NaOH+H2O2=SnO↓+SnO2↓+3H2O+4NaCl

[0032] The present application starts from the oxidation reaction principle of stannous chloride, and the stannous chloride industrial waste can be recycled by a low-cost wet method, so that the tin can be precipitated in the slag in the form of precipitate, and the chlorine can be dissolved in water, and after the slag and liquid are separated; the tin slag with low chlorine content can be directly introduced into a vacuum reduction smelting furnace to extract a refined tin product with a content of 95%.

[0033] The trace heavy metals in the stannous chloride waste will enter the vacuum reduction smelting furnace together with the tin slag, and after reduction smelting at 1500 DEG C, the melting point of the elemental tin metal obtained by reduction smelting is 232 DEG C, the liquid elemental tin metal flows out of the reduction smelting furnace, and the content of the obtained liquid elemental tin is 95%.

[0034] Compared with the prior art, the present application has the beneficial effects that: the present application uses wet aeration pre-oxidation, then adds liquid alkali to precipitate tin, recovers by pressure filtration, and then obtains a refined tin product by fire reduction smelting, and the tin recovery rate in the process is as high as 97.8% or more, water can be recycled and the amount of waste slag produced is less, it is a closed-loop process that can be recycled, the process is simple, the industrial production cost is low, the utilization rate of metal resources tin is improved, the environmental pollution caused by stannous chloride waste is improved, and it is worth popularization and application.

[0035] 1、The present application uses aeration oxidation to replace hydrogen peroxide oxidation of Sn in the prior art, and saves auxiliary material cost; 2+ 2、The present application simultaneously carries out tin precipitation and tin oxidation, saves auxiliary material cost, and simplifies the production operation process;

[0036] 2、The present application simultaneously carries out tin precipitation and tin oxidation, saves auxiliary material cost, and simplifies the production operation process;

[0037] 3、The application completes the operation of removing heavy metals in the process of recycling stannous chloride waste materials, and the filtrate only needs simple pretreatment to directly evaporate out salt, and distilled water is returned to steps 1 and 2 for recycling. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is a process flow diagram of the application;

[0039] Figure 2 It is a schematic diagram of the external structure of the stirring barrel adopted by the application;

[0040] Figure 3 It is a schematic diagram of the internal cross-sectional structure of the stirring barrel adopted by the application.

[0041] In the figure: 1, stirring barrel, 101, steam inlet, 2, aeration pipeline, 201, air pipe, 202, air inlet, 203, aeration pipe, 2031, aeration port, 204, support rod, 3, thermocouple. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the application.

[0043] The recycled 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. After the above stannous chloride industrial waste is ball milled to a particle size of ≤50 mesh, it is put into a stirring barrel, and 6 times the weight of the stannous chloride industrial waste of clean water is added to the stirring barrel for leaching and stirring. At the same time, an air compressor is started to aerate, steam is introduced into the stirring barrel to heat the barrel to a temperature of 55℃, preheating can accelerate the dissolution of the stannous chloride industrial waste, and the stirring time is 30 min. At this time, the pH of the liquid is less than 0.5.

[0044] Then, 30% liquid alkali is added to neutralize the liquid, the pH is adjusted to about 8.5, and the aeration and stirring are continued. At this time, the pH of the liquid will continue to decrease, and the liquid alkali is continuously supplemented to maintain the pH of the liquid between 8 and 9 until the pH of the liquid is stable. In this process, tin oxidation and tin precipitation occur at the same time, and about 150 min, the amount of 30% liquid alkali consumed is equal to the weight of the stannous chloride industrial waste put in.

[0045] Take supernatant analysis: Sn: ≤0.2g / L, Cl≥38g / L, indicating that tin is basically precipitated in the slag, Cl is completely dissolved into the water, and the material can be discharged for pressure filtration.

[0046] After pressure filtration, the filtrate is added to the activated carbon adsorption decolorization at a ratio of 1 / 2000 of the weight of the filtrate, and the organic matter in the filtrate is removed. After a fine filtration, a crude sodium chloride water (content: Na 26.3g / L, Cl 40.6g / L, Ni 0.005g / L, Zn 0.009g / L, Cu 0.001g / L, Pb 0.001g / L, Ca 0.03g / L, Mg 0.003g / L) is obtained. In the crude sodium chloride water, a proper amount of dilute hydrochloric acid is added to adjust the pH of the brine to pH 7-8. The salt is evaporated to obtain a sodium chloride salt byproduct, and the distilled water is returned to the stirring barrel for recycling.

[0047] The filter residue after pressure filtration is a crude tin slag, with a weight reduction of about 37% (content: Sn 70.45%, Cl 1.22%, Na 1.18%, Ni 0.15%, Zn 0.025%, Cu 0.04%, Mn 0.005%, Pb 0.085%, Ca 0.011%, Mg 0.008%). The crude tin slag is dried in a rotary kiln and then crushed to a particle size of 120 mesh. 100-200 mesh coke is added for mixing and entering a reduction smelting furnace at 1500°C. The reduction smelting of the obtained elemental tin metal with a melting point of 232°C results in the flow of liquid tin metal out of the smelting furnace, obtaining a refined tin product with a content of 98.5%. At the same time, other trace heavy metal separation operations are realized.

[0048] Through the above wet combined with fire treatment of stannous chloride industrial waste, the tin recovery rate reaches 99.1%, and high-purity refined tin products are obtained.

[0049] 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 soft mud appearance. The soft mud-like stannous chloride industrial waste is directly placed in a stirring barrel, and water 4 times the weight of the stannous chloride industrial waste is added for leaching and stirring. At the same time, an air compressor is started for aeration, and steam is introduced into the stirring barrel to heat the barrel to a temperature of 54°C to accelerate the dissolution of the stannous chloride industrial waste. The stirring time is 30 minutes, and the pH of the material liquid is <1.0 at this time.

[0050] Then add 30% liquid alkali to neutralize the feed liquid, adjust the pH to about 8.5, continue to aerate and stir, at this time the pH of the feed liquid will continue to decrease, do not interrupt the supplement of liquid alkali, always maintain the pH of the feed liquid between 8-9, until the pH of the feed liquid is stable. The tin oxidation and tin precipitation are carried out at the same time, about 150 min, the amount of 30% liquid alkali consumed is equal to 1 / 3 of the weight of the stannous chloride industrial waste.

[0051] Take the supernatant for analysis: Sn: ≤0.2 g / L, Cl: ≥25 g / L, which indicates that tin is basically precipitated in the slag, and Cl is completely dissolved in the water liquid, which can be discharged and pressure filtered.

[0052] After pressure filtration, add activated carbon to adsorb and decolorize the filtrate at a ratio of 1 / 1000 of the weight of the filtrate, remove the organic matter in the filtrate, then pass through a fine filter to obtain a crude sodium chloride water (content: Na 17.6 g / L, Cl 27.5 g / L, Ni 0.003 g / L, Zn 0.004 g / L, Cu 0.001 g / L, Pb 0.001 g / L, Ca 0.02 g / L, Mg 0.001 g / L), add an appropriate amount of dilute hydrochloric acid to the crude sodium chloride water to adjust the pH to pH 7-pH 8, evaporate the salt to obtain a sodium chloride salt byproduct, and return the distilled water to the stirring barrel for recycling.

[0053] The filter residue after pressure filtration is a crude tin slag, with a weight reduction of about 90% (content: Sn 61.38%, Cl 1.85%, Na 1.35%, Ni 0.1%, Zn 0.03%, Cu 0.04%, Mn 0.005%, Pb 0.09%, Ca 0.04%, Mg 0.008%), the crude tin slag is dried in a rotary kiln, then crushed to a particle size of 180 mesh, mixed with 100-200 mesh coke, and then added to a reduction smelting furnace for reduction smelting at 1500°C. The melting point of the elemental tin metal obtained by reduction smelting is 232°C, the liquid tin metal flows out of the smelting furnace, and a refined tin product with a content of 97.2% is obtained. At the same time, other trace heavy metal separation operations are realized.

[0054] Through the above wet and dry combined process for treating stannous chloride industrial waste, the tin recovery rate reaches 97.8%, and a high-purity refined tin product is obtained.

[0055] The recovered hard blocky stannous chloride industrial waste (content: Sn 48.35%, Cl 29.34%, Ni 0.15%, Zn 0.018%, Cu 0.05%, Mn 0.006%, Pb 0.065%, Ca 0.021%, Mg 0.012%) is ball milled to a particle size of 50 mesh or less, and is mixed with recovered soft muddy stannous chloride industrial waste (content: Sn 7.44%, Cl 6.62%, Ni 0.055%, Zn 0.012%, Cu 0.01%, Mn 0.008%, Pb 0.062%, Ca 0.013%, Mg 0.005%) at a ratio of hard blocky: soft muddy = 4:1. The mixed soft and hard stannous chloride industrial waste is placed in a stirring tank, and water is added to the stirring tank at a ratio of 5 times the weight of the total stannous chloride industrial waste. The air compressor is turned on to aerate, steam is introduced into the stirring tank to heat to a temperature of 58°C, and stirring is continued for 30 minutes. At this time, the pH of the slurry is less than 0.5.

[0056] Then, 30% liquid alkali is added to neutralize the slurry, and the pH is adjusted to about 8.5. Aeration and stirring are continued, and the pH of the slurry continues to decrease. Liquid alkali is continuously added to maintain the pH of the slurry between 8 and 9. This process continues until the pH of the slurry is stable. Tin oxidation and tin precipitation occur simultaneously during this process, and about 150 minutes are required. The amount of 30% liquid alkali consumed is equal to 3 / 4 of the weight of the stannous chloride industrial waste added.

[0057] The supernatant is analyzed: Sn: ≤0.2 g / L, Cl: ≥48 g / L, indicating that tin is substantially precipitated in the residue, and Cl is completely dissolved in the water, which can be discharged and filtered.

[0058] The filtrate after pressure filtration is added with activated carbon at a ratio of 1 / 2000 of the weight of the filtrate to adsorb and decolorize the organic matter in the filtrate. After a second filtration, crude sodium chloride water (content: Na 32.3 g / L, Cl 50.2 g / L, Ni 0.002 g / L, Zn 0.003 g / L, Cu 0.001 g / L, Pb 0.001 g / L, Ca 0.025 g / L, Mg 0.001 g / L) is obtained. A suitable amount of dilute hydrochloric acid is added to the crude sodium chloride water to adjust the pH to 7-8. The salt is evaporated to obtain a sodium chloride salt byproduct. Distilled water is returned to the stirring tank for recycling.

[0059] The filter residue after pressure filtration is a crude tin residue, with a weight reduction of about 42% (content: Sn 67.52%, Cl 1.25%, Na 1.19%, Ni 0.1%, 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, crushed to a particle size of 150 mesh, mixed with coke, and then fed into a reduction smelting furnace for reduction smelting at 1500°C. The melting point of elemental tin metal is 232°C. Liquid tin metal flows out of the smelting furnace, and a tin product with a content of 98.7% is obtained. At the same time, other trace heavy metals are separated.

[0060] Through the above wet process combined with the fire process to treat stannous chloride industrial waste, the tin recovery rate reaches 98.9%, and a high-purity tin product is obtained.

[0061] As preferred, as shown in Figure 2 , Figure 3 The stirring barrel used in the above embodiment is provided with an aeration pipeline 2, which includes a ventilation pipe 201 and an aeration pipe 203. The ventilation pipe 201 is annular and is arranged above the stirring barrel 1. An air inlet 202 is arranged on the upper side wall of the ventilation pipe 201 and is connected with the air outlet of an air compressor. Four aeration pipes 203 are arranged on the lower side wall of the ventilation pipe 201 and extend into the stirring barrel 1 and are evenly distributed along the inner side wall of the stirring barrel 1. The outer side wall of the aeration pipe 203 is fixedly connected with the inner side wall of the stirring barrel 1 through three vertically and evenly distributed supporting rods 204. The lower end of the aeration pipe 203 is inserted into the bottom of the stirring barrel 1. The lower end aeration opening 2031 is arranged as a 45° inclined opening and faces the center of the stirring barrel 1.

[0062] The arrangement of the 45° inclined aeration opening enables the compressed air to be discharged from the inclined angle to stimulate the mixture of the liquid and to enhance the oxidation effect.

[0063] A steam inlet 101 is further arranged on the upper side wall of the stirring barrel 1. The lower end of the steam inlet 101 extends into the liquid. The upper end of the steam inlet 101 is connected with a steam pipeline and is used to introduce steam into the stirring barrel 1 to preheat the liquid and accelerate the dissolution of the stannous chloride industrial waste. A thermocouple 3 is arranged on the outer side wall of the stirring barrel 1 and is used to detect the temperature in the stirring barrel 1. When the temperature in the stirring barrel 1 is above 50°C, the steam introduction is stopped. When the temperature in the stirring barrel 1 is below 50°C, steam needs to be supplemented to maintain the temperature in the stirring barrel 1 above 50°C.

[0064] The above is only a preferred embodiment of the present application. It should be noted that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A process for the production of refined tin from stannous chloride industrial waste material by a combination of wet and pyrometallurgical recovery, characterized in that, It comprises the following steps: S1, ball milling: the hard blocky stannous chloride industrial waste is soaked with water and then ball milled to a particle size of ≤50 mesh, and the soft mud stannous chloride industrial waste is omitted from this step; S2, aeration pre-oxidation: the stannous chloride industrial waste obtained after step S1 ball milling or the soft mud stannous chloride industrial waste is added to a stirring barrel, 4-10 times the weight of the stannous chloride industrial waste of water is added to the stirring barrel for mixing, stirring and dissolving, while the air compressor is started to introduce compressed air into the liquid for aeration, the temperature in the stirring barrel is set to 50-60℃, and the stirring is continued for 30 min to obtain a liquid with a pH less than 0.5; S3, liquid alkali addition tin precipitation: 30% liquid alkali is added to the stirring barrel to adjust the liquid pH to pH 8-pH 9, continuous aeration stirring is carried out, during the reaction process of the liquid, the pH will show a downward trend, and the liquid pH 8-pH 9 is maintained by continuously adding liquid alkali, until the liquid pH is stable at pH 8-pH 9 without change, to obtain SnO and SnO2 precipitate liquid; S4, filter pressing: the precipitate liquid obtained in step S3 is put into a filter press to obtain a filtrate and a filter residue; S5, reduction smelting: the filter residue obtained in step S4 is crude tin, which is transferred into a vacuum reduction smelting furnace for reduction smelting to refine a tin product with a content of ≥95%; S6, recovery of sodium chloride byproduct; the filtrate obtained in step S4 is sodium chloride brine, activated carbon is added to the sodium chloride brine, and after stirring adsorption and decolorization, the clear filtrate is obtained by precision filtration, dilute hydrochloric acid is added to the clear filtrate to adjust the pH to pH 7-pH 8, and then the clear filtrate is evaporated to obtain a crude sodium chloride salt byproduct, and the distilled water evaporated is returned to step S1 or S2 for recycling; The stirring barrel in step S2 is provided with an aeration pipeline, the aeration pipeline comprises an air inlet pipe and an aeration pipe, the air inlet pipe is annular and is arranged above the stirring barrel, an air inlet is arranged on the upper side wall of the air inlet pipe and is connected with the air outlet of the air compressor, a plurality of aeration pipes are arranged on the lower side wall of the air inlet pipe and extend into the stirring barrel, and the aeration pipes are evenly distributed along the inner side wall of the stirring barrel, the outer side wall of the aeration pipe is fixedly connected with the inner side wall of the stirring barrel through a plurality of vertical supporting rods, the lower end of the aeration pipe is inserted into the bottom of the stirring barrel, the lower end of the aeration pipe is provided with a 45° inclined opening, and the 45° inclined opening faces the center of the stirring barrel; The upper side wall of the stirring barrel in step S2 is also provided with a steam inlet, the lower end of the steam inlet extends into the liquid, the upper end of the steam inlet is connected with a steam pipeline, and the steam is introduced into the stirring barrel for heating the liquid; a thermocouple is inserted into the outer side wall of the stirring barrel for detecting the temperature in the stirring barrel, and when the temperature in the stirring barrel reaches the set temperature, the steam is stopped.

2. A process for the recovery of pure tin from industrial waste of stannous chloride by wet-combined pyro-process as claimed in claim 1, wherein the said process comprises the steps of: The reaction process in step S3 is 150 min, and after the reaction is completed, Sn in the supernatant is ≤0.2 g / L.

3. The method for preparing refined tin from industrial waste by a combination of wet and pyrometallurgical processes according to claim 1, characterized in that: The crude tin residue in step S5 needs to be transferred into a rotary kiln for drying and then crushed to a particle size of ≤100 mesh before being transferred into a reduction smelting furnace, 100-200 mesh particle size coke is added for mixing, and then the mixture is introduced into the reduction smelting furnace for reduction smelting at 1500℃.

4. The method for preparing refined tin from industrial waste by a combination of wet and pyrometallurgical processes according to claim 1, characterized in that: The amount of activated carbon added in step S6 is 1 / 2000-1 / 1000 of the mass of the filtrate.

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