A porous material based on tin sludge and a method for its production

Abstract

The application discloses a kind of porous material based on tin mud and preparation method thereof, its preparation method includes: after tin mud pickling, washing, drying, roasting ball milling, obtain the tin mud after processing;The tin mud after processing, carbon thermal reduction agent, template and deionized water are mixed, to obtain suspension;Suspension is steamed dry in stirring, after drying, heat treatment is carried out, to obtain crude porous material;Crude porous material is purified, to obtain the porous material based on tin mud of the present application.A series of pretreatment is carried out to the tin mud of electroplating tin waste, and a material with high purity containing SnO2 is obtained, and the material is made into a material with a porous structure as a base material, realizing the secondary use of tin resources, and the porous material has stable charge and discharge performance and rate performance, and can be applied to the field of lithium / sodium ion battery negative materials.The application has short production cycle, high added value, and wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of porous material preparation, specifically to a porous material based on tin slurry and its preparation method. Background Technology

[0002] Tin mud, an important secondary tin resource, is mainly composed of metallic Sn and Sn oxides. The discharge of tin mud signifies a significant waste of tin resources and increases production costs for enterprises. In recent years, with the continuous rise in metallic tin prices, the development of the recycled metallic tin industry has received increasing attention. The recycling of tin resources from tin mud can effectively supplement the world's insufficient primary tin ore resources. However, existing research on the secondary recycling of tin mud is limited to metallic tin, with few reports on the recycling of tin oxides. Chinese patent document CN109181641A prepared a tin-based sulfur dioxide sensitive material using tin mud material, modifying it through atomic doping to improve the material's response speed to sulfur dioxide gas. Chinese patent document CN111017988A prepared a tin-based formaldehyde sensitive material using tin mud material, modifying the material through atomic doping to improve the material's response speed to formaldehyde gas. However, both of these inventions utilize tin oxides from tin mud to prepare gas-sensitive materials, limiting their application scope, requiring high-quality target materials, and involving complex preparation processes. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is that the tin oxide in the existing tin sludge is not well utilized, thereby providing a porous material based on tin sludge and its preparation method.

[0004] Therefore, the present invention adopts the following technical solution:

[0005] This invention provides a method for preparing a porous material based on tin slurry, comprising the following steps:

[0006] S1: After acid washing, washing and drying, the tin mud is calcined and ball-milled to obtain the treated tin mud;

[0007] S2: Mix the treated tin sludge, carbothermic reducing agent, template and deionized water to obtain a suspension;

[0008] S3: Evaporate the suspension to dryness, and then perform heat treatment after drying to obtain a coarse porous material;

[0009] S4: Purify the crude porous material to obtain the porous material based on tin sludge.

[0010] Further, in step S1, the pickling solution is an HCl solution with a molar concentration of 1-2 mol / L, the pickling temperature is 80-85℃, the pickling time is 2-4 h, and the stirring method is magnetic stirring;

[0011] The washing process involves alternating between anhydrous ethanol and deionized water 2-4 times.

[0012] The drying process involves drying at 50-60°C in air for 16-24 hours.

[0013] The roasting is carried out at 600-700℃ in an air atmosphere for 3-4 hours.

[0014] In step S1, the treated tin sludge still needs to undergo a grinding process to ensure that the particle size of the treated tin sludge is no greater than 10 μm.

[0015] The treated tin sludge contains 95-97% SnO2 by mass percentage, with the remainder being unavoidable impurities.

[0016] The tin slurry, by mass percentage, comprises: C: 0%-4.2%, S: 0%-3.9%, SiO2: 0%-1.2%, SnO2: 82.2%-86.4%, Fe2O3: 0%-4.3%, and P2O5: 0%-1.3%.

[0017] In step S2, the template is sodium chloride, and the carbothermic reducing agent is citric acid;

[0018] The mass ratio of tin mud, citric acid, sodium chloride, and deionized water is 1:2.5:10:400.

[0019] In step S3, the evaporation is carried out simultaneously with stirring at a speed of 100-400 r / min and a temperature of 80-90℃.

[0020] The drying process involves drying at 50-60°C in air for 16-24 hours.

[0021] The heat treatment is carried out in an argon atmosphere at 500-700℃ for 3-4 hours.

[0022] In step S4, the purification process involves first soaking the crude porous material in deionized water for 12-24 hours, then washing it three times alternately with anhydrous ethanol and deionized water, and finally drying it in air at 50-60°C for 16-24 hours.

[0023] The present invention also provides a porous material based on tin slurry, which is prepared by the above-described preparation method.

[0024] Further, by mass percentage, the porous material comprises SnO2: 20%-35%, SnO: 5%-10%, and C: 50%-60%, with a particle size <10μm and a specific surface area of ​​65-105m². 2 / g.

[0025] The technical solution of this invention has the following advantages:

[0026] (1) This invention uses tin sludge, a waste product of tin plating, as a substrate to obtain a high-purity SnO2-containing material through a series of pretreatments. This material is then used as a matrix to create a porous material, thus realizing the secondary utilization of tin resources. The prepared porous material can be applied to the field of lithium / sodium-ion battery anode materials. The porous structure increases the specific surface area of ​​the material and is a bimetallic oxide material. During charging and discharging, the porous structure provides sufficient expansion space, which is beneficial to the stability of the battery anode material structure. The synergistic effect of the multiple materials makes the charge-discharge performance and rate performance of the material more stable.

[0027] (2) This invention uses tin sludge as raw material and combines the template method with the carbothermal reduction method. Compared with using pure SnO2 as raw material and using a single method, the resulting porous material has superior performance. In the process of preparing the porous material, a specific mass ratio of raw materials is used, and the final calcination time is controlled, resulting in a material with better cycle performance.

[0028] (3) The present invention has a short production cycle, high added value, and broad application prospects. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 Here are electron microscope images of the porous material obtained in Example 1 of this invention;

[0031] Figure 2 Here is an electron microscope image of the porous material obtained in Comparative Example 1 of this invention;

[0032] Figure 3 This is the N2 adsorption / desorption isotherm of Embodiment 1 of the present invention;

[0033] Figure 4 In Example 1 of the present invention, the current density was 50 mA·g -1 Charge-discharge curves;

[0034] Figure 5 Comparative Example 1 of the present invention was performed at a current density of 50 mA·g -1 Charge-discharge curves;

[0035] Figure 6 Comparative Example 2 of the present invention was performed at a current density of 50 mA·g-1 Charge-discharge curves;

[0036] Figure 7 This is the rate capability curve of Embodiment 1 of the present invention under different current density conditions;

[0037] Figure 8 This is the rate curve of Comparative Example 1 of the present invention under different current density conditions;

[0038] Figure 9 This is the rate curve of Comparative Example 2 of the present invention under different current density conditions. Detailed Implementation

[0039] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0040] The tin sludge used in this embodiment is tin sludge produced by the MSA tin plating production line of a steel plant. Its specific composition is: C: 4.2%, S: 3.7%, SiO2: 1.2%, SnO2: 85.3%, Fe2O3: 4.3%, P2O5: 1.3%. For any experimental steps or conditions not specified in this embodiment, the conventional experimental procedures or conditions described in the literature in this field can be followed. All reagents mentioned are commercially available standard reagents.

[0041] The following specific embodiments further illustrate the present invention. The examples given do not represent all embodiments of the present invention; only some embodiments are described as examples. Specific embodiments are as follows:

[0042] Example 1

[0043] This embodiment provides a porous material based on tin slurry, and the specific preparation method is as follows:

[0044] (1) Take the raw tin mud and place it in an HCl solution with a molar concentration of 2 mol / L. Stir continuously with magnetic force for 2 h at a water bath temperature of 85℃. Wash the tin mud after acid pickling by alternating washing with anhydrous ethanol and deionized water 3 times. Dry the washed tin mud in an oven at 60℃ for 24 h in an air atmosphere. Roast the dried sample in an air atmosphere at 600℃ for 2 h. Ball mill the dried tin mud for 2 h at a ball-to-material ratio of 10:1 and a rotation speed of 400 r / min. Sieve the ball-milled tin mud with a sieve mesh of 1600 mesh to make the tin mud particle size <10 μm. The processed tin mud has a SnO2 content of 97%.

[0045] (2) Mix the treated tin mud, citric acid, sodium chloride and deionized water in a mass ratio of 1:2.5:10:400 to obtain a suspension;

[0046] (3) The suspension was continuously magnetically stirred at a water bath temperature of 85°C and a stirring speed of 200 r / min until the solvent was evaporated. The dried sample was dried in an oven at 60°C for 24 h. The dried sample was then ground into a uniform powder in a mortar and placed in a tube furnace for calcination at 600°C for 4 h under argon protection to obtain a coarse porous material.

[0047] (4) Grind the coarse porous material into a uniform powder in a mortar and soak it in deionized water for 12 hours. After soaking, wash the sample by alternating washing with anhydrous ethanol and deionized water three times. After washing, dry the sample at 60°C for 24 hours to obtain the porous material based on tin mud.

[0048] Comparative Example 1

[0049] This comparative example provides a porous material, and the specific preparation method is as follows:

[0050] (1) Mix commercially available chemically pure tin dioxide, citric acid, sodium chloride and deionized water in a mass ratio of 1:2.5:10:400 to obtain a suspension;

[0051] (2) The suspension was continuously magnetically stirred at a water bath temperature of 85°C and a stirring speed of 200 r / min until the solvent was evaporated. The dried sample was dried in an oven at 60°C for 24 h. The dried sample was ground into a uniform powder in a mortar and placed in a tube furnace for calcination at 600°C for 4 h under argon protection to obtain a coarse porous material.

[0052] (3) Grind the coarse porous material into a uniform powder in a mortar and soak it in deionized water for 12 hours. After soaking, wash the sample by alternating washing with anhydrous ethanol and deionized water three times. After washing, dry the sample at 60°C for 24 hours to obtain the porous material.

[0053] Comparative Example 2

[0054] This comparative example provides a porous material based on tin sludge, the only difference from Example 1 being that sodium chloride is not added during the preparation of the suspension.

[0055] The treated tin sludge, citric acid, and deionized water were mixed in a mass ratio of 1:2.5:400 to obtain a suspension. The suspension was continuously magnetically stirred at 200 r / min in a water bath at 85°C until the solvent evaporated. The dried sample was then dried in an oven at 60°C for 24 h. The dried sample was then ground into a uniform powder in a mortar and calcined in a tube furnace at 600°C for 4 h under argon protection. The calcined sample was then ground into a uniform powder in a mortar and soaked in deionized water for 12 h. The soaked sample was then washed three times alternately with anhydrous ethanol and deionized water. The washed sample was then dried at 60°C for 24 h.

[0056] Experimental Example 1

[0057] Comparative electron micrographs of the materials obtained in Example 1 and Comparative Example 1, such as Figure 1 and Figure 2 As can be seen, the material in Comparative Example 1 has an irregular structure with a rough and porous surface; the structure in Example 1 is a spherical structure with a smooth and porous surface. The smooth and porous surface has a positive promoting effect on the material's cycle stability and specific capacity recovery performance.

[0058] Experimental Example 2

[0059] The porous material obtained in Example 1 was subjected to BET specific surface area testing, and its isotherm results are as follows: Figure 3 As shown, it exhibits type IV isotherm characteristics. The specific surface area of ​​the porous material prepared from it is 75.6 m². 2 / g, a relatively large specific surface area and suitable pore volume can improve the capacity of the material and alleviate the volume expansion of the material during charging and discharging.

[0060] Experimental Example 3

[0061] The porous materials obtained in Example 1 and Comparative Examples 1-2 were applied to button batteries for performance testing. The specific preparation method of the button batteries was as follows: the porous materials obtained in this example, acetylene black, and PVDF / NMP binder were mixed in a mass ratio of 6:2:2 to form a slurry, which was then coated onto copper foil to form a film. After drying under vacuum at 80°C for 12 hours, the film was cut and pressed into sheets. The active material content in the electrode sheets was approximately 2 mg. Pure lithium sheets were used as the counter electrode, 1.0 mol / L LiPF6 (EC:EDC = 1:1 Vol%) was used as the electrolyte, and a Celgard 2500 polypropylene separator was used. The cells were assembled into CR2025 type button half-cells in an argon-filled glove box, and electrochemical performance was tested after standing for 48 hours. The performance was tested at a current density of 50 mA·g. -1 Charge-discharge curves as follows Figure 4-6 As shown, the rate capability curves under different current density conditions are as follows: Figure 7-9 As shown, in Example 1, the initial charge / discharge specific capacity was 1004.3 mAh·g. -1 / 721.1mAh·g -1 After 50 cycles, the charge / discharge specific capacity is 433.9 mAh·g. -1 / 422.5mAh·g -1 The initial charge / discharge specific capacity in Comparative Example 1 was 925.6 mAh·g. -1 / 426.7mAh·g -1 After 50 cycles, the charge / discharge specific capacity is 127.2 mAh·g⁻¹ / 123.8 mAh·g⁻¹. -1 The initial charge / discharge specific capacity in Comparative Example 2 was 1309.8 mAh·g. -1 / 659.3mAh·g -1 After 50 cycles, the charge / discharge specific capacity is 96.1 mAh·g. -1 / 96mAh·g -1 As can be seen, the porous material obtained in Example 1 of this application has significantly improved cycle performance and high cycle stability. Under different current densities, the charge-discharge specific capacity of Example 1 is higher than that of the comparative example. Through comparison, it can be seen that the example has better reversibility and capacity recovery.

[0062] Test Example 4

[0063] The calcination time during heat treatment in step (3) of Example 1 was changed, and the initial specific capacity and the specific capacity after 50 cycles were measured. The results are shown in the table below:

[0064] Table 1. Performance comparison of different calcination times

[0065]

[0066] As can be seen from the table above, a long calcination time wastes energy and reduces too much tin dioxide, resulting in a lower carbon content in the material, which is detrimental to the material's structural stability. Although the initial specific capacity is high, the cycle stability is very poor, and the specific capacity decreases significantly after 50 cycles. If the calcination time is too short, too little tin monoxide is reduced, resulting in a low initial specific capacity of the material. After 50 cycles, the material's specific capacity also suffers a significant loss.

[0067] Experimental Example 5

[0068] By changing the proportions of the materials used in preparing the suspension in Example 1, the initial specific capacity and the specific capacity after 50 cycles were measured. The results are shown in the table below:

[0069] Table 2 Comparison of performance of different material ratios

[0070]

[0071] As can be seen from the table above, a low citric acid content results in a low carbon content in the prepared material, which is detrimental to the structural stability of the material during charge-discharge processes. Too high a citric acid content affects the initial specific capacity of the material. Too little sodium chloride results in a material with low pore content and small pore size, and the volume expansion problem during charge-discharge processes is not fully resolved. Too high a sodium chloride content results in large pore volumes during template preparation, but performance is not improved.

[0072] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a porous material based on tin slurry, characterized in that, Includes the following steps: S1: After acid washing, washing and drying, the tin mud is then roasted and ball-milled to obtain the treated tin mud; the acid washing solution is an HCl solution with a molar concentration of 1-2 mol / L and an acid washing temperature of 80-85℃; the washing is performed by alternating washing with anhydrous ethanol and deionized water 2-4 times. S2: Mix the treated tin sludge, carbothermic reducing agent, template and deionized water to obtain a suspension; the template is sodium chloride and the carbothermic reducing agent is citric acid; the mass ratio of tin sludge, citric acid, sodium chloride and deionized water is 1:2.5:10:400; S3: Evaporate the suspension to dryness, and then perform heat treatment after drying to obtain a coarse porous material; S4: Purify the crude porous material to obtain the porous material based on tin sludge; In step S3, the heat treatment is calcination at 500-700°C for 4 hours in an argon atmosphere; The tin slurry, by mass percentage, comprises: C: 4.2%, S: 3.7%, SiO2: 1.2%, SnO2: 85.3%, Fe2O3: 4.3%, and P2O5: 1.3%. The porous material comprises, by mass percentage, 30% SnO2, 10% SnO, and 60% C, with a particle size <10 μm and a specific surface area of ​​65-105 m². 2 / g.

2. The preparation method according to claim 1, characterized in that, In step S1, the pickling time is 3-4 hours, and stirring is carried out during pickling using magnetic stirring. The drying process involves drying at 50-60°C in air for 16-24 hours. The roasting is carried out at 600-700℃ in an air atmosphere for 2-4 hours.

3. The preparation method according to claim 1 or 2, characterized in that, In step S1, the treated tin sludge still needs to undergo a grinding process to ensure that the particle size of the treated tin sludge is no greater than 10 μm. The treated tin sludge contains 95-97% SnO2 by mass percentage, with the remainder being unavoidable impurities.

4. The preparation method according to claim 1, characterized in that, In step S3, the evaporation is carried out simultaneously with stirring at a speed of 100-400 r / min and a temperature of 80-90℃. The drying process involves drying at 50-60°C in air for 16-24 hours.

5. The preparation method according to claim 1, characterized in that, In step S4, the purification process involves first soaking the crude porous material in deionized water for 12-24 hours, then washing it three times alternately with anhydrous ethanol and deionized water, and finally drying it in air at 50-60°C for 16-24 hours.

6. A porous material based on tin slurry, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

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