Method for preparing aluminum hydroxide based on coal-based solid waste

Abstract

The invention belongs to the technical field of aluminum hydroxide preparation, and particularly relates to a method for preparing aluminum hydroxide based on coal-based solid waste. The silicon dioxide mesoporous material is prepared from tetraethyl silicate and ferroferric oxide and is used for impurity removal treatment, and the modified activated carbon is used for impurity removal treatment, so that the purity of the prepared aluminum hydroxide is improved, the impurity content is reduced, and meanwhile, the particle size is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum hydroxide preparation, and specifically relates to a method for preparing aluminum hydroxide based on coal-based solid waste. Background Art

[0002] Aluminum hydroxide is the main raw material for the preparation of metallurgical grade alumina, and can also be used as a flame retardant and toothpaste and agate filler. Bauxite is currently the most important resource in the production of aluminum hydroxide, but my country's bauxite resources are not abundant, which directly restricts the production of aluminum hydroxide. At the same time, due to the high coal consumption in my country, coal gangue as a solid waste generated during coal mining, washing and processing has also increased year by year. The use of coal gangue to prepare aluminum hydroxide not only alleviates the current shortage of bauxite in my country but also realizes the comprehensive utilization of industrial waste.

[0003] A Chinese patent (publication number CN202310010746.X) discloses a method for preparing aluminum hydroxide from coal gangue. The invention mixes coal gangue powder, sodium carbonate and slaked lime powder and then calcines to obtain clinker; the clinker is impregnated in an acidic solution, concentrated and then thermally decomposed to obtain a pyrolysis solid product, and then the pyrolysis solid product is impregnated in an alkaline solution and purified to obtain solid aluminum hydroxide; the invention uses slaked lime powder and sodium carbonate as calcination activation aids to improve the chemical activity of the calcined coal gangue, thereby increasing the aluminum leaching rate, while reducing the amount of sodium carbonate, effectively reducing the production cost; at the same time, the method has a low thermal decomposition temperature and a short time, thereby reducing energy consumption in the process and reducing carbon emissions. In addition, the aluminum element extraction rate is high, the production cost is low, and it is suitable for industrial scale-up production. However, the patent does not solve the problem that the aluminum hydroxide prepared based on coal-based solid waste in the prior art has a large impurity content and the aluminum hydroxide particle size is too large, which seriously affects its actual use.

[0004] Therefore, there is an urgent need for a method for preparing aluminum hydroxide based on coal-based solid waste, which can improve the purity of the prepared aluminum hydroxide, reduce the impurity content, and reduce the particle size by performing effective impurity removal and purification treatments. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing aluminum hydroxide based on coal-based solid waste, by using tetraethyl silicate and ferrosoferric oxide to prepare a silicon dioxide mesoporous material and use it for impurity removal treatment, using modified activated carbon for impurity removal treatment, thereby improving the purity of the prepared aluminum hydroxide, reducing the impurity content, and reducing the particle size.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: The present invention provides a method for preparing aluminum hydroxide based on coal-based solid waste, comprising the following steps: Step S1: crush the gangue with a crusher and grind it in a planetary rod mill for 60 to 90 minutes. After grinding, pass it through a sieve to obtain gangue powder; Step S2: transferring the coal gangue powder to a high temperature furnace and heating it to 900-1000° C., keeping the temperature for 3-5 hours, and then cooling it to room temperature with the furnace to obtain a calcined material; Step S3: adding 1000-1200 parts of the calcined material to 2000-2400 parts of acid solution by weight for dissolution reaction, filtering after the dissolution reaction is completed to obtain an acidic filtrate; Step S4: removing impurities from the acidic filtrate through a silica mesoporous material to obtain a filtrate after impurities removal; Step S5: purifying the impurity-removed filtrate through activated carbon to obtain a purified filtrate; Step S6: adding 200 to 300 parts of a precipitant to 1000 to 1200 parts of the purified filtrate by weight to carry out a precipitation reaction, filtering after the precipitation reaction is completed to obtain a precipitate, washing, drying, and roasting to obtain aluminum hydroxide.

[0007] As a preferred solution, the mesh size of the sieve is 100-120 meshes.

[0008] As a preferred solution, the acid solution is sulfuric acid and hydrochloric acid; the mass ratio of the sulfuric acid to the hydrochloric acid is (1~2):1.

[0009] As a preferred solution, the dissolution reaction conditions include: stirring speed of 100-200 rpm, temperature of 140-150° C., and time of 4-6 h.

[0010] By controlling the appropriate amounts of sulfuric acid and hydrochloric acid in the acid solution, a good compounding effect can be achieved, the purity of the prepared aluminum hydroxide can be improved, the impurity content can be reduced, and the particle size can be reduced.

[0011] As a preferred scheme, the preparation method of the silica mesoporous material includes: mixing 100-120 parts of anhydrous ethanol and 30-40 parts of deionized water by weight, then adding 2-4 parts of ferrosoferric oxide and ultrasonically dispersing for 1-3 hours to obtain a suspension, adding 8-10 parts of tetraethyl silicate and 4-6 parts of ammonia water to the suspension, reacting for 12-16 hours under stirring at room temperature, filtering after the reaction is completed, washing the filter residue with anhydrous ethanol, and drying to obtain the silica mesoporous material.

[0012] Silica mesoporous materials can reduce the impurity content through multiple effects. First, the large specific surface area and multiple pores provided by the mesoporous structure allow impurities to be adsorbed into the material through physical effects such as van der Waals forces. Secondly, ferrosoferric oxide gives the material magnetism, which can effectively adsorb impurities such as iron.

[0013] As a preferred solution, the activated carbon is modified activated carbon; the preparation method of the modified activated carbon comprises: dispersing 6 to 10 parts of activated carbon in a mixed solution of 20 to 24 parts of sulfuric acid and 26 to 30 parts of nitric acid, ultrasonically dispersing for 60 to 90 minutes at a power of 800 to 1000 W, then heat treating for 60 to 90 minutes at 150 to 160° C., and filtering to obtain an acidified intermediate; adding 6 to 10 parts of the acidified intermediate to 80 to 100 parts of N,N-dimethylformamide and ultrasonically dispersing for 30 to 40 minutes, then adding 4 to 6 parts of dicyclohexylcarbodiimide, 1 to 3 parts of 4-dimethylaminopyridine and 6 to 8 parts of acrylic acid, placing under nitrogen atmosphere protection, reacting at 82 to 88° C. for 20 to 24 hours, filtering, washing with water, and drying to obtain the modified activated carbon.

[0014] As a preferred solution, the average particle size of the activated carbon is 80-120 mesh.

[0015] By modifying the surface of activated carbon, carboxyl groups are introduced. As a strong polar group, carboxyl groups can combine with impurities through hydrogen bonds, electrostatic interactions or chemical adsorption, thereby reducing the impurity content and facilitating the subsequent particle size refinement of aluminum hydroxide.

[0016] As a preferred solution, the mass ratio of sodium carbonate to ammonia water is (1-2):1.

[0017] As a preferred solution, the conditions of the precipitation reaction include: stirring speed of 200-400 rpm, temperature of 60-70° C., and time of 2-4 h.

[0018] As a preferred solution, the calcination conditions include: temperature of 120-140° C. and time of 2-4 hours.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention achieves a good compounding effect by controlling the appropriate amount of sulfuric acid and hydrochloric acid in the acid solution, and uses tetraethyl silicate and ferrosoferric oxide to prepare a mesoporous silicon dioxide material and use it for impurity removal treatment, and uses modified activated carbon for impurity removal treatment, thereby improving the purity of the prepared aluminum hydroxide, reducing the impurity content, and reducing the particle size.

[0020] 2. The silica mesoporous material of the present invention can reduce the impurity content through multiple effects. First, the large specific surface area and multiple pores provided by the mesoporous structure allow impurities to be adsorbed into the material through physical effects such as van der Waals forces. Secondly, ferrosoferric oxide gives the material magnetism, which can achieve effective adsorption of impurities such as iron.

[0021] 3. The modified activated carbon of the present invention introduces carboxyl groups by surface modification of activated carbon. As a strong polar group, carboxyl groups can combine with impurities through hydrogen bonds, electrostatic interactions or chemical adsorption, thereby reducing the impurity content in the product and facilitating the subsequent particle size refinement of aluminum hydroxide. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0023] The sources of some components in the embodiments and comparative examples are as follows: Coal gangue, model CG61, purchased from Shanxi Haohengyuan Mining Co., Ltd.; Sulfuric acid, CAS No. 7664-93-9, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Hydrochloric acid, CAS No. 7647-01-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Mesoporous silica, product number S433664, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Activated carbon I, product number C299105, average particle size 100 mesh, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Activated carbon II, product number A768977, average particle size 200 mesh, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Activated carbon III, product number A805342, average particle size 12 mesh, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Sodium carbonate, CAS No. 497-19-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Ammonia water, CAS No. 1336-21-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Ferroferric oxide, CAS No. 1317-61-9, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Tetraethyl silicate, CAS No. 78-10-4, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Nitric acid, CAS No. 7697-37-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.; N,N-dimethylformamide, CAS No. 68-12-2, purchased from Sinopharm Chemical Reagent Co., Ltd.; Dicyclohexylcarbodiimide, CAS No. 538-75-0, purchased from Zhongshan Dixin Chemical Co., Ltd.; 4-Dimethylaminopyridine, CAS No. 1122-58-3, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Acrylic acid, CAS No. 79-10-7, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0024] Example 1 This embodiment provides a method for preparing aluminum hydroxide based on coal-based solid waste, comprising the following steps: Preparation of mesoporous silica material: In parts by weight, mix 120 parts of anhydrous ethanol and 40 parts of deionized water, then add 4 parts of ferrosoferric oxide and ultrasonically disperse for 3 hours to obtain a suspension, add 10 parts of tetraethyl silicate and 6 parts of ammonia water to the suspension, react at room temperature with stirring for 16 hours, filter after the reaction is completed, wash the filter residue with anhydrous ethanol, and dry to obtain a mesoporous silica material.

[0025] Preparation of modified activated carbon: In parts by weight, 10 parts of activated carbon I (average particle size of 100 mesh) are dispersed in a mixture of 24 parts of sulfuric acid and 26 parts of nitric acid, ultrasonically dispersed for 60 minutes at a power of 1000 W, and then heat treated at 160°C for 60 minutes, and filtered to obtain an acidified intermediate; 10 parts of the acidified intermediate are added to 100 parts of N,N-dimethylformamide and ultrasonically dispersed for 40 minutes, and then 6 parts of dicyclohexylcarbodiimide, 3 parts of 4-dimethylaminopyridine and 8 parts of acrylic acid are added, placed in a nitrogen atmosphere for protection, reacted at 88°C for 20 hours, filtered, washed with water, and dried to obtain modified activated carbon.

[0026] Step S1: crush the gangue using a crusher and grind it in a planetary rod mill for 90 minutes. After grinding, pass it through a sieve (with a mesh size of 120) to obtain gangue powder; Step S2: transferring the coal gangue powder to a high temperature furnace and heating it to 1000° C., keeping the temperature for 3 hours, and then cooling it to room temperature with the furnace to obtain a calcined material; Step S3: adding 1200 parts of the calcined material to 2400 parts of acid solution (1600 parts of sulfuric acid and 800 parts of hydrochloric acid) by weight for dissolution reaction (stirring speed of 200 rpm, temperature of 150° C., time of 4 hours), filtering after the dissolution reaction is completed to obtain an acidic filtrate; Step S4: removing impurities from the acidic filtrate through a silica mesoporous material to obtain a filtrate after impurities removal; Step S5: purifying the impurity-removed filtrate through modified activated carbon to obtain a purified filtrate; Step S6: Add 300 parts of precipitant (200 parts of sodium carbonate and 100 parts of ammonia water) to 1000-1200 parts of the purified filtrate by weight to carry out precipitation reaction (stirring speed is 400 rpm, temperature is 70°C, time is 2h), filter after the precipitation reaction is completed to obtain a precipitate, wash with water, dry, and roast (temperature is 140°C, time is 2h) to obtain aluminum hydroxide.

[0027] Example 2 This embodiment provides a method for preparing aluminum hydroxide based on coal-based solid waste, comprising the following steps: Preparation of mesoporous silica material: In parts by weight, mix 120 parts of anhydrous ethanol and 40 parts of deionized water, then add 4 parts of ferrosoferric oxide and ultrasonically disperse for 3 hours to obtain a suspension, add 10 parts of tetraethyl silicate and 6 parts of ammonia water to the suspension, react at room temperature with stirring for 16 hours, filter after the reaction is completed, wash the filter residue with anhydrous ethanol, and dry to obtain a mesoporous silica material.

[0028] Preparation of modified activated carbon: In parts by weight, 10 parts of activated carbon I (average particle size of 100 mesh) are dispersed in a mixture of 20 parts of sulfuric acid and 30 parts of nitric acid, ultrasonically dispersed at a power of 800 W for 90 minutes, then heat treated at 160°C for 60 minutes, and filtered to obtain an acidified intermediate; 6 parts of the acidified intermediate are added to 80 parts of N,N-dimethylformamide and ultrasonically dispersed for 30 minutes, then 4 parts of dicyclohexylcarbodiimide, 1 part of 4-dimethylaminopyridine and 6 parts of acrylic acid are added, placed in a nitrogen atmosphere for protection, reacted at 82°C for 24 hours, filtered, washed with water, and dried to obtain modified activated carbon.

[0029] Step S1: crushing the gangue with a crusher and grinding it in a planetary rod mill for 60 minutes, and then passing it through a sieve (mesh size of 100) to obtain gangue powder; Step S2: transferring the coal gangue powder to a high temperature furnace and heating it to 900° C., keeping the temperature for 5 hours, and then cooling it to room temperature with the furnace to obtain a calcined material; Step S3: adding 1000 parts of the calcined material to 2000 parts of acid solution (1000 parts of sulfuric acid and 1000 parts of hydrochloric acid) by weight for dissolution reaction (stirring speed of 100 rpm, temperature of 140° C., time of 6 hours), filtering after the dissolution reaction is completed to obtain an acidic filtrate; Step S4: removing impurities from the acidic filtrate through a silica mesoporous material to obtain a filtrate after impurities removal; Step S5: purifying the impurity-removed filtrate through modified activated carbon to obtain a purified filtrate; Step S6: Add 200 parts of precipitant (100 parts of sodium carbonate and 100 parts of ammonia water) to 1000 parts of the purified filtrate by weight to carry out precipitation reaction (stirring speed is 200 rpm, temperature is 60°C, time is 4 hours). After the precipitation reaction is completed, filter to obtain a precipitate, wash with water, dry, and roast (temperature is 120°C, time is 4 hours) to obtain aluminum hydroxide.

[0030] Example 3 This embodiment provides a method for preparing aluminum hydroxide based on coal-based solid waste, comprising the following steps: Preparation of mesoporous silica material: In parts by weight, mix 110 parts of anhydrous ethanol and 35 parts of deionized water, then add 3 parts of ferrosoferric oxide and ultrasonically disperse for 2 hours to obtain a suspension, add 9 parts of tetraethyl silicate and 5 parts of ammonia water to the suspension, react at room temperature with stirring for 14 hours, filter after the reaction is completed, wash the filter residue with anhydrous ethanol, and dry to obtain a mesoporous silica material.

[0031] Preparation of modified activated carbon: 8 parts of activated carbon I (average particle size of 100 mesh) are dispersed in a mixture of 22 parts of sulfuric acid and 28 parts of nitric acid, ultrasonically dispersed at a power of 900 W for 80 minutes, and then heat treated at 155°C for 80 minutes, and filtered to obtain an acidified intermediate; 8 parts of the acidified intermediate are added to 90 parts of N,N-dimethylformamide and ultrasonically dispersed for 35 minutes, and then 5 parts of dicyclohexylcarbodiimide, 2 parts of 4-dimethylaminopyridine and 7 parts of acrylic acid are added, placed in a nitrogen atmosphere for protection, reacted at 85°C for 22 hours, filtered, washed with water, and dried to obtain modified activated carbon.

[0032] Step S1: crushing the gangue with a crusher and grinding it in a planetary rod mill for 80 minutes, and then passing it through a sieve (mesh size of 100) to obtain gangue powder; Step S2: transferring the coal gangue powder to a high temperature furnace and heating it to 950° C., keeping the temperature for 4 hours, and then cooling it to room temperature with the furnace to obtain a calcined material; Step S3: adding 1100 parts of the calcined material to 2200 parts of acid solution (1400 parts of sulfuric acid and 800 parts of hydrochloric acid) by weight for dissolution reaction (stirring speed of 150 rpm, temperature of 145° C., time of 5 h), filtering after the dissolution reaction is completed to obtain an acidic filtrate; Step S4: removing impurities from the acidic filtrate through a silica mesoporous material to obtain a filtrate after impurities removal; Step S5: purifying the impurity-removed filtrate through modified activated carbon to obtain a purified filtrate; Step S6: Add 250 parts of precipitant (150 parts of sodium carbonate and 100 parts of ammonia water) to 1100 parts of the purified filtrate by weight to carry out precipitation reaction (stirring speed is 300 rpm, temperature is 65°C, time is 3 hours). After the precipitation reaction is completed, filter to obtain a precipitate, wash with water, dry, and roast (temperature is 130°C, time is 3 hours) to obtain aluminum hydroxide.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is that the amount of sulfuric acid in the acid solution is changed to 2000 parts, and the amount of hydrochloric acid is changed to 400 parts.

[0034] Comparative Example 2 The difference between this comparative example and Example 1 is that the amount of sulfuric acid in the acid solution is changed to 800 parts, and the amount of hydrochloric acid is changed to 1600 parts.

[0035] Comparative Example 3 The difference between this comparative example and Example 1 is that the impurity removal treatment uses commercially available mesoporous silica to replace the silica mesoporous material.

[0036] Comparative Example 4 The difference between this comparative example and Example 1 is that activated carbon I is used in the purification process instead of modified activated carbon.

[0037] Comparative Example 5 The difference between this comparative example and Example 1 is that activated carbon II is used instead of activated carbon I to prepare the modified activated carbon.

[0038] Comparative Example 6 The difference between this comparative example and Example 1 is that activated carbon III is used instead of activated carbon I to prepare the modified activated carbon.

[0039] The aluminum hydroxide of the above examples and comparative examples was subjected to the following tests: (1) the impurity content was tested with reference to the requirements of GB / T 4294-2010 Aluminum Hydroxide; (2) the particle size was tested with reference to the requirements of YS / T 738.5-2020 Analysis Method of Aluminum Hydroxide for Fillers Part 5: Determination of Particle Size.

[0040] Table 1 Performance test results

[0041] It can be seen from the above performance test results that Examples 1-3 have good effects, with impurity contents of 0.31-0.39% and particle sizes of 3.2-3.8 μm; this is because the appropriate amounts of sulfuric acid and hydrochloric acid are controlled in the acid solution to achieve a good compounding effect, while tetraethyl silicate and ferrosoferric oxide are used to prepare mesoporous silica materials and used for impurity removal treatment, and modified activated carbon is used for impurity removal treatment, thereby improving the purity of the prepared aluminum hydroxide, reducing the impurity content, and reducing the particle size.

[0042] The comparative example did not adopt the necessary technical solution, resulting in its performance being significantly worse than that of the embodiment; compared with Example 1, the amount of sulfuric acid in the acid solution of Comparative Example 1 was changed to 2000 parts, and the amount of hydrochloric acid was changed to 400 parts. Due to the excessive amount of sulfuric acid, the compounding effect was not good, the impurity content increased, and the particle size increased; compared with Example 1, the amount of sulfuric acid in the acid solution of Comparative Example 2 was changed to 800 parts, and the amount of hydrochloric acid was changed to 1600 parts. Due to the insufficient amount of sulfuric acid, the compounding effect was not good, the impurity content increased, and the particle size increased; compared with Example 1, the impurity removal treatment of Comparative Example 3 used commercially available mesoporous silica instead of silica mesoporous material, so the impurity The content is increased and the particle size is increased; compared with Example 1, in the purification treatment of Comparative Example 4, activated carbon I is used instead of modified activated carbon, and the impurity content is increased and the particle size is increased; compared with Example 1, activated carbon II is used instead of activated carbon I to prepare modified activated carbon in Comparative Example 5. Since the particle size of activated carbon II is too large and the modification effect is not good, the impurity content is increased and the particle size is increased; compared with Example 1, activated carbon III is used instead of activated carbon I to prepare modified activated carbon in Comparative Example 6. Since the particle size of activated carbon III is too small and the modification effect is not good, the impurity content is increased and the particle size is increased; the above experimental results further prove the importance of the technical scheme defined in the present invention for its technical effect.

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

Claims

1. A method for preparing aluminum hydroxide based on coal-based solid waste, characterized in that: The following steps are involved: Step S1: crush the gangue with a crusher and grind it in a planetary rod mill for 60 to 90 minutes. After grinding, pass it through a sieve to obtain gangue powder; Step S2: transferring the coal gangue powder to a high temperature furnace and heating it to 900-1000° C., keeping the temperature for 3-5 hours, and then cooling it to room temperature with the furnace to obtain a calcined material; Step S3: adding 1000-1200 parts of the calcined material to 2000-2400 parts of acid solution by weight for dissolution reaction, filtering after the dissolution reaction is completed to obtain an acidic filtrate; Step S4: removing impurities from the acidic filtrate through a silica mesoporous material to obtain a filtrate after impurities removal; Step S5: purifying the impurity-removed filtrate through activated carbon to obtain a purified filtrate; Step S6: adding 200 to 300 parts of a precipitant to 1000 to 1200 parts of the purified filtrate by weight to carry out a precipitation reaction, filtering after the precipitation reaction is completed to obtain a precipitate, washing, drying, and roasting to obtain aluminum hydroxide.

2. A method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The mesh number of the sieve is 100-120 meshes.

3. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The acid solution is sulfuric acid and hydrochloric acid; the mass ratio of the sulfuric acid to the hydrochloric acid is (1~2):

1.

4. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The dissolution reaction conditions include: stirring speed of 100-200 rpm, temperature of 140-150° C., and time of 4-6 h.

5. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The preparation method of the silica mesoporous material comprises: mixing 100-120 parts of anhydrous ethanol and 30-40 parts of deionized water by weight, then adding 2-4 parts of ferrosoferric oxide and ultrasonically dispersing for 1-3 hours to obtain a suspension, adding 8-10 parts of tetraethyl silicate and 4-6 parts of ammonia water to the suspension, reacting for 12-16 hours under stirring at room temperature, filtering after the reaction is completed, washing the filter residue with anhydrous ethanol, and drying to obtain the silica mesoporous material.

6. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The activated carbon is modified activated carbon; The preparation method of the modified activated carbon comprises: dispersing 6 to 10 parts of activated carbon in a mixed solution of 20 to 24 parts of sulfuric acid and 26 to 30 parts of nitric acid by weight, ultrasonically dispersing the mixture for 60 to 90 minutes at a power of 800 to 1000 W, then heat treating the mixture at 150 to 160° C. for 60 to 90 minutes, and filtering to obtain an acidified intermediate; adding 6 to 10 parts of the acidified intermediate to 80 to 100 parts of N,N-dimethylformamide and ultrasonically dispersing the mixture for 30 to 40 minutes, then adding 4 to 6 parts of dicyclohexylcarbodiimide, 1 to 3 parts of 4-dimethylaminopyridine and 6 to 8 parts of acrylic acid, placing the mixture under nitrogen atmosphere protection, reacting the mixture at 82 to 88° C. for 20 to 24 hours, filtering, washing with water, and drying to obtain the modified activated carbon.

7. A method for preparing aluminum hydroxide based on coal-based solid waste according to claim 6, characterized in that: The average particle size of the activated carbon is 80-120 meshes.

8. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The precipitating agents are sodium carbonate and ammonia water; the mass ratio of the sodium carbonate to ammonia water is (1-2):

1.

9. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The conditions of the precipitation reaction include: stirring speed of 200-400 rpm, temperature of 60-70° C., and time of 2-4 h.

10. The method for preparing aluminum hydroxide based on coal-based solid waste according to claim 1, characterized in that: The calcination conditions include: a temperature of 120-140° C. and a time of 2-4 hours.

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