Method for preparing activated carbon from ultralow ash anthracite

Abstract

The invention belongs to the technical field of coal processing, and particularly discloses a method for preparing activated carbon from ultralow-ash anthracite, ultrapure coal with ash content lower than 1.5% is prepared from anthracite by a physical-chemical method, and the ultrapure coal is used as a raw material to prepare the activated carbon. The ultra-pure coal subjected to ash removal treatment has the characteristics of low ash content, high carbon content and the like; the ash content is low, so that the interference of impurities on the activation process can be reduced, the activator can act on the coal more effectively, and formation of a pore structure is promoted; the high carbon content provides a sufficient carbon source for preparation of the activated carbon, formation of a developed carbon skeleton structure is facilitated, and more pores can be generated in the activation process, so that the specific surface area and the adsorption capacity of the activated carbon are increased, and the efficiency of the activated carbon is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal processing, in particular to a method for preparing activated carbon by utilizing ultra-low ash anthracite. Background Art

[0002] The mined coal needs to be processed before it can be used in the future. When used as fuel, the presence of nitrogen and sulfur compounds, aluminosilicates and other inorganic compounds in coal leads to incomplete combustion of coal and the emission of large amounts of polluting gases such as carbon dioxide and sulfur dioxide, which greatly pollutes the environment.

[0003] With the improvement of environmental protection requirements and the transformation of energy structure, the use of traditional coal is restricted. Ultra-pure coal, as a high-value-added coal product with an ash content of less than 2%, has the advantages of low ash, low sulfur, and high calorific value. Its application in the preparation of carbon materials such as oil-water coal slurry, high-grade activated carbon, and carbon fiber composite materials is increasingly valued. Anthracite is the most coalified type of coal, with a carbon content of up to 90% to 98%. This allows it to provide a higher carbon content in the process of preparing ultra-pure coal, reduce the interference of minerals, and thus improve the quality of ultra-pure coal.

[0004] Activated carbon plays an important role in environmental governance, water purification, air purification and other fields due to its strong adsorption capacity. Using ultra-pure coal prepared from anthracite to prepare activated carbon is an important manifestation of the high added value of coal, and it also plays an important role in the environment. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing activated carbon using anthracite.

[0006] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0007] A method for preparing activated carbon using ultra-low ash anthracite comprises the following steps:

[0008] S1. Grinding anthracite raw material with an ash content of 10 wt% into anthracite particles with a particle size of less than 0.074 mm;

[0009] S2, flotation pretreatment of anthracite particles;

[0010] S3, mixing the anthracite particles pre-treated by flotation with 0.7 mol / L citric acid, placing them in a water bath at 80°C and stirring for 120 minutes; the treated reactants are also cooled, centrifuged, washed and dried;

[0011] S4, subjecting the anthracite particles treated with citric acid to ultrasonic flotation to prepare ultrapure coal;

[0012] S5. In an air-tight condition, the ultrapure coal is placed in a carbonization furnace; in the drying stage, the furnace temperature is raised to 150°C and maintained for 2 hours; then, the furnace temperature is gradually raised to between 150 and 270°C to enter the initial carbonization stage and maintained for 3 hours; the furnace temperature is further raised to 360 to 600°C for high-temperature carbonization and maintained for 6 hours to obtain a carbonized material;

[0013] S6, after cooling the carbonized material, put it into an activation furnace and rapidly heat it to 800°C, so that the remaining volatile matter leaves the solid phase material in the form of gas; gradually heat it up to control the entire activation temperature at 860-960°C, and activate the carbonized material under high temperature environment by injecting water vapor, carbon dioxide and air as activation media under high pressure to obtain crude activated carbon;

[0014] S7. Cooling the crude activated carbon to room temperature, washing it to remove residual activating agent and impurities, and drying it to obtain the final activated carbon product.

[0015] Furthermore, in step S2, the flotation pretreatment includes a roughing selection and a fine selection in a flotation machine; the flotation pretreatment is carried out in the flotation machine, and the collector used is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25 kg / t; the bubbling agent used is 2-octanol, and the dosage is 1.80 kg / t; the pulping intensity is 1800 r / min.

[0016] Furthermore, in step S4, the process of ultrasonic flotation treatment is as follows: during the flotation process, ultrasonic treatment at 20 Hz is performed synchronously until the formation of the foam layer stops; then flotation is performed, and the flotation conditions are as follows: the collector is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25 kg / t; the bubbling agent is octanol, and the dosage is 1.80 kg / t; the pulping intensity is increased to 2200 r / min; and the flotation includes a roughing selection and a fine selection.

[0017] Furthermore, the volume ratio of the water vapor, carbon dioxide and air is 1:1:1, the flow rate is 400-500 ml / min, and the activation time is 1-2 hours.

[0018] Compared with the prior art, the present invention uses anthracite to prepare ultra-pure coal with an ash content of less than 1.5% by a physical-chemical method, and uses the ultra-pure coal as a raw material to prepare activated carbon; considering the porous surface environment of the activated carbon, a weak acid, namely citric acid, is used to pickle the coal sample after flotation, and the metal oxides or inorganic minerals in the coal will be deashed to a certain extent during the treatment process, and then ultrasonic synchronous flotation is further used to clean the surface of the coal sample after the pickling treatment, and the number of tiny bubbles in the slurry will be increased, thereby increasing the collision probability between mineral particles and bubbles. At the same time, the stirring speed was adjusted from 1800 to 2200, which to a certain extent enhanced the turbulent environment in the flotation process, further promoted the adhesion of coal particles and tiny bubbles in the slurry, enhanced the mineralization process, and at the same time, reduced the ash entrainment caused by the strong turbulent environment and the contamination of the clean coal; the ultra-pure coal after deashing has the characteristics of low ash content and high carbon content; low ash content can reduce the interference of impurities on the activation process, so that the activator can act on the coal more effectively and promote the formation of pore structure; high carbon content provides sufficient carbon source for the preparation of activated carbon, which is conducive to the formation of a developed carbon skeleton structure, and can generate more pores during the activation process, thereby increasing the specific surface area and adsorption capacity of activated carbon, greatly improving the efficiency of activated carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the activated carbon product. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0021] This embodiment exemplarily shows a method for preparing activated carbon using anthracite, and the specific steps are as follows:

[0022] S1. Grinding anthracite raw material with an ash content of 10 wt% into anthracite particles with a particle size of less than 0.074 mm;

[0023] S2. The anthracite particles are subjected to a roughing and a cleaning in the XFD1 flotation machine. The flotation pretreatment is carried out in the XFD1 flotation machine. The collector used is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25 kg / t; the bubbling agent used is octanol, and the dosage is 1.80 kg / t; the slurry intensity is 1800 r / min;

[0024] S3. Mix the anthracite particles pretreated by flotation with 0.7 mol / L citric acid and place them in a water bath at 80° C. and stir for 120 min. The treated reactants are also cooled, centrifuged, washed and dried.

[0025] S4, the anthracite particles treated with citric acid are subjected to ultrasonic flotation again to prepare ultra-pure coal: during the flotation process, 20HZ ultrasonic treatment is performed synchronously until the formation of the foam layer stops; then flotation is performed, and the flotation conditions are: the collector is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25kg / t; the bubbling agent used is octanol, and the dosage is 1.80kg / t; the slurry adjustment intensity is increased to 2200r / min; and the flotation includes one roughing and one fine selection. It has been measured that the ash content of the ultra-pure coal sample prepared in this embodiment is less than 1.5%; low ash content can reduce the interference of impurities on the activation process, so that the activator can act more effectively on the coal and promote the formation of pore structure; high carbon content provides sufficient carbon source for the preparation of activated carbon, which is conducive to the formation of a developed carbon skeleton structure, and can generate more pores during the activation process, thereby increasing the specific surface area and adsorption capacity of activated carbon, and greatly improving the efficiency of activated carbon.

[0026] S5. In an air-tight condition, the pretreated ultrapure coal sample is placed in a carbonization furnace; during the drying stage, the furnace temperature is raised to 150°C and maintained for 2 hours; then, the furnace temperature is gradually raised to between 150 and 270°C to enter the initial carbonization stage and maintained for 3 hours; the furnace temperature is further raised to 360 to 600°C for high-temperature carbonization and maintained for 6 hours to obtain a carbonized material;

[0027] S6, after cooling the carbonized material, put it into an activation furnace and rapidly heat it to 800°C, so that the residual volatile matter leaves the solid phase material in the form of gas; gradually heat it up to control the entire activation temperature at 860-960°C, and activate the carbonized material under high temperature environment by injecting water vapor, carbon dioxide, and air as activation media under high pressure, the volume ratio of water vapor, carbon dioxide, and air is 1:1:1, the flow rate is 400-500ml / min, and the activation time is 1-2 hours; obtain crude activated carbon; in this embodiment, the carbonized material is reacted with oxidizing gases such as water vapor, carbon dioxide or air at high temperature with the carbon material, so that the disordered carbon in the carbon material is partially oxidized and etched into pores, and a developed microporous structure is formed inside the material. Its main chemical reaction formula is as follows:

[0028] C + 2H2O → 2H2 + CO2;

[0029] C+H2O→H2+CO;

[0030] C+CO2→2CO;

[0031] The formation of microporous structure increases the specific surface area and adsorption capacity of activated carbon, greatly improving the efficiency of activated carbon. The charging ratio of activation gas is 1:1:1, and each part of the gas injected plays a different role in the activation process. Steam activation: Water vapor reacts with carbon at high temperature, such as: C+H2O→CO+H2.

[0032] This reaction mainly forms a microporous structure inside the activated carbon.

[0033] S7. Cooling the crude activated carbon to room temperature, washing it to remove residual activating agent and impurities, and drying it to obtain the final activated carbon product.

[0034] The scanning electron microscope image of the activated carbon product is as follows Figure 1 As shown, from Figure 1 It can be seen that activated carbon has abundant micropores, which help to adsorb small molecules.

[0035] Carbon dioxide activation: The reaction of CO2 with carbon (C+CO2→2CO) also helps to form pores, but the pores formed are usually slightly larger than those formed by water vapor. Figure 1 Some medium-sized pores can be observed in the sample, which is largely the result of CO2 activation. Such medium-sized pores can adsorb relatively large molecules.

[0036] Air activation: Although oxygen is more intense during the activation process, an appropriate amount of oxygen (2C+O2→2CO) helps to form a certain amount of pores on the surface and inside of the activated carbon, and can modify and connect the pore structure. Figure 1 It can be seen that there is a certain connectivity between the pores, which is the contribution of air activation.

[0037] In summary, the activated carbon prepared by the present invention has the characteristics of high specific surface area, high porosity, uneven particle size and shape, and rough surface structure. At the same time, some pores are large and deep, while others are small and shallow. This structure has a wide range of application value in adsorption and filtration.

[0038] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing activated carbon using ultra-low ash anthracite, characterized in that: The following steps are involved: S1. Grinding anthracite raw material with an ash content of 10 wt% into anthracite particles with a particle size of less than 0.074 mm; S2, flotation pretreatment of anthracite particles; S3, mixing the anthracite particles pre-treated by flotation with 0.7 mol / L citric acid, placing them in a water bath at 80°C and stirring for 120 minutes; the treated reactants are also cooled, centrifuged, washed and dried; S4, subjecting the anthracite particles treated with citric acid to ultrasonic flotation to prepare ultrapure coal; S5. Put the ultrapure coal into the carbonization furnace under air-tight conditions; in the drying stage, raise the furnace temperature to 150°C and keep it for 2 hours; then gradually raise the furnace temperature to between 150 and 270°C to enter the initial carbonization stage and keep it for 3 hours; the furnace temperature continues to rise to 360 to 600°C for high-temperature carbonization and keep it for 6 hours to obtain the carbonized material; S6, after cooling the carbonized material, put it into an activation furnace and rapidly heat it to 800°C, so that the remaining volatile matter leaves the solid phase material in the form of gas; gradually heat it up to control the entire activation temperature at 860-960°C, and activate the carbonized material under high temperature environment by injecting water vapor, carbon dioxide and air as activation media under high pressure to obtain crude activated carbon; S7. Cooling the crude activated carbon to room temperature, washing it to remove residual activating agent and impurities, and drying it to obtain the final activated carbon product.

2. The method for preparing activated carbon using ultra-low ash anthracite according to claim 1, characterized in that: In the step S2, the flotation pretreatment includes a roughing and a cleaning in the flotation machine; the flotation pretreatment is carried out in the flotation machine, the collector used is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25 kg / t; the bubbling agent used is 2-octanol, and the dosage is 1.80 kg / t; the pulping intensity is 1800 r / min.

3. The method for preparing activated carbon using ultra-low ash anthracite according to claim 1, characterized in that: In step S4, the process of ultrasonic flotation treatment is: synchronously perform ultrasonic treatment at 20 Hz during the flotation process until the formation of the foam layer stops; then perform flotation, and the flotation conditions are: the collector is a composite agent composed of kerosene and methyl oleate in a volume ratio of 4:3, and the dosage is 3.25 kg / t; the bubbling agent is 2-octanol, and the dosage is 1.80 kg / t; the pulping intensity is increased to 2200 r / min; and the flotation includes a roughing selection and a fine selection.

4. The method for preparing activated carbon using ultra-low ash anthracite according to claim 1, characterized in that: The volume ratio of the water vapor, carbon dioxide and air is 1:1:1, the flow rate is 400-500 ml / min, and the activation time is 1-2 hours.

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