Introduction of main production process and raw materials of powdered activated carbon
Generally, coal-based powdered activated carbon is produced in the form of other types of activated carbon by-products. In the case of separate production, the bulk raw coal is first crushed and sieved into raw coal powder of acceptable size according to the production process requirements, and then carbonized and activated. The finished powdered activated carbon is obtained.
Coal-based powdered activated carbon is mainly used for upper and lower water treatment, waste incineration flue gas purification treatment and soil improvement. Because of the low market price, it is often not economically feasible to produce coal-based powdered activated carbon separately. There is no manufacturer of coal-based powdered activated carbon. At present, coal-based powdered activated carbon products are basically derived from the undersize produced by coal-based granular activated carbon producers at the same time as the production of granular activated carbon, and these undersize materials are ground into powdered powdered activated carbon for sale as a by-product. At present, the foreign coal-based powdered activated carbon production company only Norit let the company, the company uses peat to produce coal-based powdered activated carbon for the purification of waste incineration flue gas.
Gas activation method for preparing activated carbon
The gas activation method is also called physical activation method. It uses water vapor, flue gas (main component is co2), air or other oxygen-containing gas or mixed gas as activator, and is activated by contact with carbonized material at high temperature or alternating between two activators. It is activated to produce activated carbon products with large specific surface area and developed pores.
The activation reaction belongs to the heterogeneous reaction of the gas-solid phase system. The activation process includes physical and chemical processes. The whole process includes the diffusion of the activator into the outer surface of the carbonized material and the diffusion of the activator to the inner surface of the carbonized material. The activator is adsorbed by the inner and outer surfaces of the carbonized material, the gasification reaction occurs on the surface of the carbonized material to form an intermediate product (surface complex), the intermediate product is decomposed into a reaction product, the reaction product is desorbed, and the reaction product is desorbed from the activated carbon carbonized material. The process of diffusing the inner surface to the outer surface.
The material has formed a basic microcrystalline structure similar to graphite during the carbonization process, forming a primary pore structure between the crystallites, but some of the disordered amorphous carbon or tar is produced due to the carbonation of these primary pore structures. The material is clogged or closed, so the specific surface area of ​​the carbonized material is small. The process of gas activation is a process in which an activated gas undergoes a redox reaction with C to erode the surface of the carbide, and at the same time removes the tar-like substance and the carbonized material to develop a fine pore structure of the carbonized material. Through the gasification reaction, the original occluded pores of the carbonized material are opened, the original pores are enlarged, the pore walls are burned out, and some structures are selectively activated to produce new pores. The formation of pores is closely related to the degree of oxidation of C. The deeper the degree of gasification reaction between activated gas and carbonized material in a certain range of activation loss rate, the larger the specific surface area of ​​activated carbon, the more developed the pores, and the activated carbon. The better the adsorption performance. According to Dubinn's theory, when the loss rate is less than 50%, microporous activated carbon is obtained; when the loss rate is greater than 75%, macroporous activated carbon is obtained; when the loss rate is 50% to 75%, What is obtained is an activated carbon having a mixed structure.
Raw coal crushed activated carbon production process:
The raw coal crushing activated carbon production process is a relatively simple production process in coal-based activated carbon production, with low production cost and low equipment investment. The process uses the qualified particle size raw coal as raw material, and directly produces the crushed amorphous carbon waste by carbonization and activation. The production process is that the bulk raw coal is crushed and sieved into the qualified granular materials according to the production requirements, first enters the human body. The carbonization furnace is carbonized, and then the powder is removed by sieving to form a qualified carbonized material; the qualified carbonized material is activated into activating material by activating the furnace, and the activated material is crushed and sieved into finished granular activated carbon of different particle size grades, and the powder is sieved. Powdered activated carbon can be made into a by-product by milling. According to the market demand, the granular activated carbon products of different particle size grades can be made into low-ash granular activated carbon products by pickling or high temperature and high pressure alkali.
The raw coal crushing activated carbon process is more suitable for raw coal with higher physical strength and reactivity directly through carbonization and activation to produce crushed amorphous granular activated carbon. The obtained granular activated carbon has higher strength, but for anthracite and other coal with relatively low chemical activity. The particle activated carbon obtained by this process has a poor adsorption index, so it is not suitable for the production of granular activated carbon from anthracite and other coal types.
The granular activated carbon produced by the process is mainly used for industrial wastewater treatment, and some large granular products can be used for caramel decolorization and monosodium glutamate treatment; its by-product powdered activated carbon can be used for water treatment, and can also be used for waste incineration purification treatment.
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