Method for recovering and preparing tin from lead slag

Abstract

The invention relates to the technical field of metal metallurgy, in particular to a method for recovering and preparing tin from lead slag, which comprises the following steps: S1, crushing and sorting; s2, mixing and pressing; s3, chlorination reaction; s4, performing water immersion for the first time; s5, alkali fusion reaction; s6, second-time water immersion; the recovery rate of tin is high, the recovered sodium stannate product is widely applied to the industries of electroplating, spinning, printing and dyeing, ceramics, electronic industry and the like, emission of heavy metal tin in the lead-acid storage battery is reduced, serious pollution of the heavy metal tin to soil and water sources is reduced, the heavy metal tin in the lead-acid storage battery is recycled, and the environment is protected. And resource waste is reduced, the tin recovery rate is high, environmental pollution is reduced, and economic benefits are improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for recovering and preparing tin from lead slag. Background Art

[0002] As a widely used energy storage device, lead-acid batteries are widely used in transportation, power storage, electric bicycles, and backup power supplies, playing an indispensable role in people's daily lives.

[0003] With the large-scale application of lead-acid batteries in various fields, the scrapping of waste lead-acid batteries has become an important issue. According to statistics, the scrapping of lead-acid batteries in China reaches millions of tons each year. These waste lead-acid batteries contain a large amount of valuable metals, such as lead, tin, copper, etc. If these waste lead-acid batteries are not properly handled, the heavy metal tin in them will cause serious pollution to the soil and water sources, thereby threatening the ecosystem and human health. As a limited natural resource, tin will cause resource loss and waste if it is not recycled. Traditional processes for the recovery of tin in lead-acid batteries include solid phase electrolysis, oxygen-enriched side-blown furnace molten pool intensification, etc. Smelting process: The solid-phase electrolysis process requires a large amount of electricity to maintain, which will lead to higher energy consumption and thus increase costs; the oxygen-enriched side-blown furnace molten pool enhanced smelting process: Since the oxygen-enriched side-blowing smelting technology recovers more impurities in the waste, there are problems of low product purity and high smoke dust rate in the process of recovering tin; the chlorination - water immersion - alkali fusion - water immersion - concentrated crystallization process can effectively reduce energy consumption and smoke dust pollution, but if there is no filtration after water immersion or the filtration effect is poor, insoluble solid impurities will remain in the solution, affecting the subsequent purification and metal recovery steps, and reducing the purity and recovery efficiency of the product.

[0004] Therefore, the present invention provides a method for recovering and preparing tin from lead slag to solve the problems raised in the above background technology. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering and preparing tin from lead slag, so as to solve the problems existing in the prior art that the heavy metal tin in waste batteries is not recovered, causing serious pollution to soil and water sources, leading to the loss and waste of resources, and the traditional process consumes high energy, pollutes the environment, and has low recovery efficiency.

[0006] In order to solve the above technical problems, the present invention provides a method for recovering tin from lead slag, comprising the following steps:

[0007] S1. Crushing and sorting: waste lead-acid batteries are crushed and sorted to separate tin-lead slag;

[0008] S2, mixing and pressing: tin-lead slag and ammonium chloride are mixed evenly in a mass ratio of 6:1 to 25:1 and pressed into a block;

[0009] S3, chlorination reaction: the pressed block mixture is placed in a crucible, and placed in a quartz tube heating zone, the heating temperature is: 625-700 ° C, the heating time is 30-60 minutes, the air pressure in the system is adjusted to 5pa-100kpa by a vacuum gauge, and the chlorination condensation product is condensed and collected; the obtained chlorination condensation product is remixed with the tin-lead slag, and the chlorination reaction is carried out again, and the operation is cyclically operated until the tin content in the chlorination condensation product reaches 0.5-5wt%;

[0010] S4, first water immersion: the chlorinated condensate product is subjected to water immersion, the solid-liquid ratio is controlled to be 90-150 g / l, and the leaching time is 1-6 hours; after the leaching is completed, the filtrate and the tin-rich material are separated by using a water immersion device (1) through a first filter box (2) and a second filter box (3);

[0011] S5, alkali fusion reaction: mixing the tin-rich material with sodium hydroxide in a certain proportion, and carrying out alkali fusion reaction; controlling the alkali fusion temperature to be 400-600°C, and the smelting time to be 3-6 hours; cooling after the reaction to obtain a smelting product;

[0012] S6, second water leaching: the smelting product is water-leached, the solid-liquid ratio is controlled to be 90-150 g / l, and the leaching time is 2-4 hours; after the leaching is completed, the filtrate and the leaching residue are obtained by filtering through the first filter box (2) and the second filter box (3) using the water leaching device (1); the filtrate is concentrated and crystallized to prepare the sodium stannate product;

[0013] S7, Concentration and crystallization: Concentration and crystallization are carried out by heating evaporation, and the evaporation temperature is controlled at 85°C-90°C. When the sodium hydroxide concentration in the leaching solution reaches 300-400g / l, the heating and evaporation are stopped, and the solution is cooled and crystallized and filtered to obtain the sodium stannate product.

[0014] A further improvement of the technical solution of the present invention is that in step S2, the tin-lead slag and ammonium chloride are uniformly mixed in a mass ratio of 6:1 to 20:1 and pressed into a block to facilitate the subsequent heating reaction.

[0015] A further improvement of the technical solution of the present invention is that the solid-liquid separator 1 comprises a first filter box 2 and a second filter box 3 , and a gate valve 4 is arranged between the first filter box 2 and the second filter box 3 .

[0016] A further improvement of the technical solution of the present invention is that a first filter bucket 21 is adapted to be mounted in the first filter box 2, a filter plate 22 is arranged on the first filter bucket 21 against one side of the plug valve 4, an upper filter screen 221 is arranged on the upper half of the filter plate 22, and the upper filter screen 221 is a mesh with a flat surface, and a lower filter screen 222 is arranged on the lower part of the filter plate 22, and the lower filter screen 222 is a mesh with a wavy surface.

[0017] A further improvement of the technical solution of the present invention is that the bottom surface of the first filter bucket 21 is tilted downward toward the direction of the gate valve 4, and the tilt angle is 30 to 60 degrees.

[0018] A further improvement of the technical solution of the present invention is that the second filter box 3 includes an upper box body 31 connected to the plug valve 4, the lower part of the upper box body 31 is connected to the lower box body 32, and the second filter bucket 33 is adapted to be mounted in the lower box body 32. The second filter bucket 33 has a square frame at the upper part and a bucket-shaped structure that shrinks toward the center at the lower part.

[0019] A further improvement of the technical solution of the present invention is that the mesh number of the filter plate 22 is 100-200 meshes, and the mesh number of the second filter bucket 33 is 200-400 meshes.

[0020] A further improvement of the technical solution of the present invention is that a discharge valve 34 is provided on the bottom surface of the second filter box 3 to discharge the filtrate in the second filter box 3 .

[0021] A further improvement of the technical solution of the present invention is that a handle 5 is provided on the upper end surface of the first filter bucket 21 , and a handle 5 is provided on the upper end surface of the second filter bucket 33 .

[0022] A further improvement of the technical solution of the present invention is that: the first filter box 2 and the second filter box 3 are both made of polytetrafluoroethylene; and support columns 6 are respectively provided at the four corners of the bottom of the first filter box 2 and the second filter box 3 .

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] 1. The present invention provides a method for recovering tin from lead slag. The method comprises the steps of crushing and sorting, mixing and pressing, chlorination reaction, first water immersion, alkali fusion reaction, second water immersion, and concentrated crystallization to obtain a sodium stannate product. The tin recovery rate is high. The recovered sodium stannate product is widely used in electroplating, textile, printing and dyeing, ceramics, electronics and other industries, reduces the emission of heavy metal tin in lead-acid batteries, reduces the serious pollution of heavy metal tin to soil and water sources, and recycles the heavy metal tin in lead-acid batteries, reduces the waste of resources, and improves economic benefits.

[0025] 2. The present invention provides a method for recovering and preparing tin from lead slag. In the method, a water immersion device is used to effectively separate the chlorinated condensation product after the first water immersion into a filtrate and a tin-rich product; the purity of the tin-rich product is improved, and the water immersion device is used to effectively filter the smelting product after the second water immersion to obtain a filtrate; the purity of the filtrate is improved, the production process is accelerated, and the efficiency of tin product preparation is improved.

[0026] 3. A method for recovering and preparing tin from lead slag provided by the present invention, in which a first filter bucket is suitably mounted in a first filter box of a water immersion device, a filter plate is arranged on the upper part of the first filter bucket against one side of a gate valve, an upper filter screen is arranged on the upper half of the filter plate, and the upper filter screen is in the shape of a mesh with a flat surface, a lower filter screen is arranged on the lower part of the filter plate, and the lower filter screen is in the shape of a mesh with a wavy surface, after the gate valve is opened, the chlorinated condensate product after the first water immersion is filtered through the filter plate, and since the tin-rich substance is precipitated at the lower part of the filtrate, the flow rate of the mixture of the filtrate and the tin-rich substance at the lower part is slowed down when passing through the first filter bucket, the wavy lower filter screen arranged at the lower part of the first filter bucket increases the contact area with the mixture of the filtrate and the tin-rich substance, avoids the filter holes on the lower filter screen from being blocked prematurely, and allows the filtrate to flow into the second filter box more smoothly, and the bottom of the first filter bucket is arranged to be inclined downward, which helps the chlorinated condensate product liquid after the water immersion to flow to the second filter box, thereby increasing the flow rate and improving the filtering efficiency;

[0027] The tin-rich leaching product is filtered, which reduces resource waste and improves the efficiency of tin product preparation.

[0028] 4. The present invention provides a method for recovering and preparing tin from lead slag. In the method, a second filter bucket is adapted to be mounted in the lower box of a second filter box of a water immersion device. The second filter bucket performs secondary filtration on the filtrate in the first filter box, thereby improving the recovery rate of tin-rich substances in the chlorinated condensation product after the first water immersion and the purity of the filtrate collected after the second water immersion, thereby improving the recovery rate of tin and reducing resource waste. The second filter bucket has a square frame on the upper part and a bucket-shaped structure that shrinks toward the center at the lower part. The second filter bucket with a bucket-shaped structure increases the turbulence of the fluid, thereby increasing the collision probability and mass transfer rate of particulate matter, improving the filtration efficiency, and improving the efficiency of tin product preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A flow chart of the steps of a method for recovering tin from lead slag;

[0031] Figure 2 It is a schematic diagram of the structure of the water immersion device;

[0032] Figure 3 is a structural schematic diagram of the first filter bucket;

[0033] Figure 4 is a structural schematic diagram of the second filter bucket;

[0034] Figure numerals: 1. solid-liquid separator; 2. first filter box; 3. second filter box; 4. gate valve; 5. handle; 6. support column; 21. first filter bucket; 22. filter plate; 221. upper filter screen; 222. lower filter screen; 31. upper box body; 32. lower box body; 33. second filter bucket; 34. discharge valve. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The present invention is further explained below in conjunction with specific implementation modes.

[0039] like Figure 1-4 As shown, this embodiment provides a method for recovering tin from lead slag, comprising the following steps:

[0040] S1. Crushing and sorting: The waste lead-acid batteries are crushed and sorted to separate the tin-lead slag; before crushing, the electrolyte of the waste lead-acid batteries needs to be poured out for centralized treatment; Crushing: First use a common punch press for preliminary crushing, then use a crocodile crusher for mechanical crushing, and then use a ball mill for fine grinding;

[0041] S2. Mixing and pressing: Evenly mix the tin-lead slag and ammonium chloride in a mass ratio of 6:1 to 25:1 and press them into blocks; by pressing, the density of the mixture of tin-lead slag and ammonium chloride increases, and the gaps between powder particles decrease, thereby improving the efficiency of subsequent reactions; the pressed block material has a more uniform density distribution, so that the next chlorination reaction absorbs heat more evenly and improves thermal efficiency.

[0042] Furthermore, the tin-lead slag and ammonium chloride are uniformly mixed in a mass ratio of 6:1 to 20:1 and pressed into blocks. The setting of this mass ratio ensures that the subsequent chlorination heating reaction is fully carried out, thereby improving the reaction efficiency and the recovery rate of tin.

[0043] S3, chlorination reaction: the pressed block mixture is placed in a crucible, and placed in a quartz tube heating zone, the heating temperature is: 625-700 ° C, the heating time is 30-60 minutes, the air pressure in the system is adjusted to 5Pa-100KPa by a vacuum gauge, under this heating condition, the tin in the tin-lead slag is converted into tin chloride, the tin chloride is easy to volatilize under this condition, and the chlorination reagent will also volatilize, and the volatile substances are condensed to obtain a chlorination condensation product, which contains ammonium chloride and tin chloride, and the chlorination condensation product is condensed and collected; the obtained chlorination condensation product is mixed with the tin-lead slag again, and the chlorination reaction is carried out again, and the operation is cyclically repeated until the tin content in the chlorination condensation product reaches 0.5-5wt%.

[0044] S4, first water immersion: the chlorinated condensation product is water immersed, the solid-liquid ratio is controlled to be 90-150g / l, and the leaching time is 1-6 hours; during the leaching process, ammonium chloride is dissolved in water, and ammonium chloride reacts with tin in the tin-containing lead slag as a chlorinating agent to generate tin chloride. Under alkaline conditions, tin chloride can react with water to generate tin hydroxide, and the tin-containing substance undergoes a precipitation reaction to generate tin hydroxide or tin oxide. After leaching is completed, a water immersion device 1 is used to pass through the first filter box 2 and the second filter box 3 to separate the filtrate and the tin-rich material.

[0045] The water immersion device 1 includes a first filter box 2 and a second filter box 3. The first filter box 2 and the second filter box 3 are both provided with a box cover (not shown in the figure). When water immersion is performed, the box cover is covered and the chlorinated condensate product is placed in the first filter box 2 in the water immersion device 1. A gate valve 4 is provided between the first filter box 2 and the second filter box 3 (the gate valve is an existing product and is not described here). The gate valve 4 valve body is made of PTFE material to utilize its excellent corrosion resistance and chemical stability to prevent the chlorinated condensate product from reacting with it, so as to improve the purity of the chlorinated condensate product; at this time, the gate valve 4 provided between the first filter box 2 and the second filter box 3 is in a closed state; the chlorinated condensate product is immersed in the first filter box 2 for 1-6 hours. After the first immersion is completed, the gate valve 4 is opened, and the filtrate flows from the first filter box 2 into the second filter box 3. The first filter box 2 is equipped with a first filter hopper 21. The first filter hopper 21 is attached to one side of the gate valve 4 and a filter plate 22 is arranged. An upper filter screen 221 is arranged on the upper half of the filter plate 2. The upper filter screen 221 is a mesh with a flat surface. A lower filter screen 222 is arranged on the lower part of the filter plate 22. The lower filter screen 222 is a mesh with a wavy surface. The bottom surface of the first filter hopper 21 is tilted downward toward the gate valve 4, and the tilt angle is 30 to 60 degrees. After the first water immersion, the chlorinated condensed product is filtered through the filter plate. Since the tin-rich substances are precipitated at the lower part of the filtrate, the mixture of the filtrate and the tin-rich substances at the lower part slows down the flow rate through the first filter hopper. The wavy lower filter screen arranged at the lower part of the first filter hopper increases the contact area with the mixture of the filtrate and the tin-rich substances, avoids the filter holes on the lower filter screen from being blocked prematurely, and allows the filtrate to flow into the second filter box more smoothly. The bottom of the first filter hopper is arranged to be tilted downward, which helps the chlorinated condensed product liquid after the water immersion to flow to the second filter box, improves the flow rate, and improves the filtering efficiency.

[0046] The filtrate flows from the first filter box 2 into the second filter box 3. The second filter box 3 includes an upper box body 31 connected to the plug valve 4. The lower part of the upper box body 31 is connected to the lower box body 32. The second filter bucket 33 is adapted to be mounted in the lower box body 32. The upper part of the second filter bucket 33 is a square frame, and the lower part is a bucket-shaped structure that shrinks toward the center. The second filter bucket is adapted to be mounted in the lower box body of the second filter box. The second filter bucket performs secondary filtration on the filtrate in the first filter box. The mesh number of the filter plate 22 is 100-200 meshes, and the mesh number of the second filter bucket 33 is 200-400 meshes.

[0047] The second filter bucket performs the second filtration, better intercepts the tiny tin-rich substances in the filtrate, increases the extraction amount of tin-rich substances, increases the recovery rate of tin-rich substances in the chlorination condensation product after the first water immersion, increases the recovery rate of tin, and reduces resource waste; the square frame on the upper part of the second filter bucket, and the lower part is a bucket-shaped structure that shrinks toward the center. The second filter bucket with a bucket-shaped structure increases the turbulence of the fluid, thereby increasing the collision probability and mass transfer rate of the particles, improving the filtration efficiency, and improving the efficiency of tin product preparation. After the filtration is completed, a discharge valve 34 is set on the bottom surface of the second filter box 3 to discharge the filtrate in the second filter box 3. The first filter bucket 21 and the second filter bucket 33 have residual tin-rich substances; the upper end surface of the first filter bucket 21 is provided with a handle 5, and the upper end surface of the second filter bucket 33 is provided with a handle 5. The first filter bucket 21 and the second filter bucket 33 are pulled by hand to take out the first filter bucket 21 and the second filter bucket 33 from the first filter box 2 and the second filter box 3, respectively, and the tin-rich substances are collected for the next step of alkali melting reaction.

[0048] Furthermore, the first filter box 2 and the second filter box 3 are both made of polytetrafluoroethylene; taking advantage of its excellent corrosion resistance and chemical stability, the chlorinated condensation products are prevented from reacting with it, so as to improve the purity of the chlorinated condensation products; support columns 6 are respectively arranged at the four corners of the bottom of the first filter box 2 and the second filter box 3, which are used to support the first filter box 2 and the second filter box 3, so as to improve the stability of the first filter box 2 and the second filter box 3.

[0049] S5. Alkali fusion reaction: the tin-rich material and sodium hydroxide are mixed in a certain proportion to carry out an alkali fusion reaction; the alkali fusion temperature is controlled to be 400-600°C, and the smelting time is 3-6 hours; during the reaction, the tin-containing material reacts with sodium hydroxide to be converted into sodium stannate, and after the reaction is completed, the mixture is cooled to obtain a smelting product.

[0050] S6, second water immersion: immerse the smelting product in water, control the solid-liquid ratio to 90-150g / l, and the leaching time to 2-4 hours; put the smelting product into the first filter box 2 in the water immersion device 1, and leach the smelting product in the first filter box for 2-4 hours. After the leaching is completed and the second water immersion is completed, open the gate valve 4, and the smelting product after water immersion flows from the first filter box 2 through the filter plate 22 into the second filter box 3; the filtrate passes through the second filter bucket 33 from the second filter box 3, and is discharged from the bottom surface of the second filter box 3 by the discharge valve 34. The filtrate that has been filtered twice is collected, and the two filtrations can effectively remove more impurities and improve the filtration efficiency. The first filtration can remove larger particles, and the second filtration can further remove smaller particles, thereby obtaining a purer filtrate; ensuring the purity of the final filtrate; improving the filtration efficiency and tin recovery rate, and reducing resource waste;

[0051] S7. Concentration and crystallization: Concentration and crystallization are carried out by heating evaporation. The evaporation temperature is controlled at 85°C-90°C. The evaporation and crystallization temperature of sodium stannate under normal pressure is 85°C. The evaporation temperature is set to 85°C-90°C to ensure that the sodium stannate is fully evaporated, concentrated and crystallized. When the sodium hydroxide concentration in the leachate reaches 300-400g / l, the heating and evaporation are stopped. After cooling and crystallization, the sodium stannate product is obtained by filtration.

[0052] During the entire process, the tin recovery rate can reach more than 90%. Through this process, tin can be efficiently recovered from tin-lead slag. The recovered sodium stannate products are widely used in electroplating, textile, printing and dyeing, ceramics, electronics and other industries, reducing the emission of heavy metal tin in lead-acid batteries and the serious pollution of heavy metal tin to soil and water sources. The heavy metal tin in lead-acid batteries can be recycled, reducing the waste of resources and improving economic benefits.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering tin from lead slag, characterized in that: The steps include: S1. Crushing and sorting: waste lead-acid batteries are crushed and sorted to separate tin-lead slag; S2, mixing and pressing: tin-lead slag and ammonium chloride are mixed evenly in a mass ratio of 6:1 to 25:1 and pressed into a block; S3, chlorination reaction: the pressed block mixture is placed in a crucible, and placed in a quartz tube heating zone, the heating temperature is: 625-700 ° C, the heating time is 30-60 minutes, the air pressure in the system is adjusted to 5pa-100kpa by a vacuum gauge, and the chlorination condensation product is condensed and collected; the obtained chlorination condensation product is remixed with the tin-lead slag, and the chlorination reaction is carried out again, and the operation is cyclically operated until the tin content in the chlorination condensation product reaches 0.5-5wt%; S4, first water immersion: the chlorinated condensate product is subjected to water immersion, the solid-liquid ratio is controlled to be 90-150 g / l, and the leaching time is 1-6 hours; after the leaching is completed, the filtrate and the tin-rich material are separated by using a water immersion device (1) through a first filter box (2) and a second filter box (3); S5, alkali fusion reaction: mixing the tin-rich material with sodium hydroxide in a certain proportion, and carrying out alkali fusion reaction; controlling the alkali fusion temperature to be 400-600°C, and the smelting time to be 3-6 hours; cooling after the reaction to obtain a smelting product; S6, second water leaching: the smelting product is water-leached, the solid-liquid ratio is controlled to be 90-150 g / l, and the leaching time is 2-4 hours; after the leaching is completed, the filtrate and the leaching residue are obtained by filtering through the first filter box (2) and the second filter box (3) using the water leaching device (1); the filtrate is concentrated and crystallized to prepare the sodium stannate product; S7, Concentration and crystallization: Concentration and crystallization are carried out by heating evaporation, and the evaporation temperature is controlled at 85°C-90°C. When the sodium hydroxide concentration in the leaching solution reaches 300-400g / l, the heating and evaporation are stopped, and the solution is cooled and crystallized and filtered to obtain the sodium stannate product.

2. A method for recovering tin from lead slag according to claim 1, characterized in that: In step S2, the tin-lead slag and ammonium chloride are mixed uniformly in a mass ratio of 6:1 to 20:1 and pressed into a block to facilitate the subsequent heating reaction.

3. A method for recovering tin from lead slag according to claim 1, characterized in that: The solid-liquid separator (1) comprises a first filter box (2) and a second filter box (3), and a gate valve (4) is arranged between the first filter box (2) and the second filter box (3).

4. A method for recovering tin from lead slag according to claim 2, characterized in that: A first filter hopper (21) is adapted to be mounted in the first filter box (2). The first filter hopper (21) is provided with a filter plate (22) abutting against one side of the plug valve (4). An upper filter screen (221) is provided on the upper half of the filter plate (22). The upper filter screen (221) is in the shape of a mesh with a flat surface. A lower filter screen (222) is provided on the lower part of the filter plate (22). The lower filter screen (222) is in the shape of a mesh with a wavy surface.

5. According to the method for recovering tin from lead slag as described in claim 2, the bottom surface of the first filter bucket (21) is tilted downward toward the gate valve (4) at an angle of 30 to 60 degrees.

6. A method for recovering tin from lead slag according to claim 2, characterized in that: The second filter box (3) comprises an upper box body (31) connected to the gate valve (4); the lower part of the upper box body (31) is connected to the lower box body (32); a second filter bucket (33) is adapted to be mounted in the lower box body (32); the upper part of the second filter bucket (33) is a square frame, and the lower part is a bucket-shaped structure that shrinks toward the center.

7. A method for recovering tin from lead slag according to claim 2, characterized in that: The mesh number of the filter plate (22) is 100-200 meshes, and the mesh number of the second filter bucket (33) is 200-400 meshes.

8. A method for recovering tin from lead slag according to claim 2, characterized in that: A discharge valve (34) is provided on the bottom surface of the second filter box (3) for discharging the filtrate in the second filter box (3).

9. A method for recovering tin from lead slag according to claim 2, characterized in that: A handle (5) is provided on the upper end surface of the first filter bucket (21), and a handle (5) is provided on the upper end surface of the second filter bucket (33).

10. A method for recovering tin from lead slag according to claim 1, characterized in that: The first filter box (2) and the second filter box (3) are both made of polytetrafluoroethylene; support columns (6) are respectively arranged at the four corners of the bottom of the first filter box (2) and the second filter box (3).

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