Method and system for preparing high-whiteness and high-purity aluminum hydroxide from solid waste

Abstract

The invention relates to a method and a system for preparing high-whiteness and high-purity aluminum hydroxide from solid waste. The preparation method comprises the following steps: firstly, crushing raw materials to form pre-powder, preparing raw materials from the pre-powder, molding the pre-powder to obtain a blank, sintering the blank to obtain clinker, dissolving out the clinker to obtain slurry, and carrying out slurry desilication, carbon component reaction, hydrogen-aluminum separation and drying on the slurry to prepare the high-whiteness and high-purity aluminum hydroxide. The raw materials comprise aluminum-containing solid waste, calcium-containing solid waste, pulverized coal and sodium carbonate; the raw material crushing comprises the step of crushing the raw materials to process control fineness; and blank sintering refers to temperature programming roasting of the blank, and the roasting temperature ranges from 800 DEG C to 1100 DEG C. According to the invention, solid wastes such as fly ash, coal gangue, carbide slag and the like, pulverized coal and sodium carbonate are crushed into materials with the same fineness, high-whiteness and high-purity aluminum hydroxide can be obtained through alkali-process blank sintering, the recovery rate of aluminum in the solid wastes is 90% or above, and harmless, resource and synergistic utilization of the solid wastes such as fly ash and the like is realized.

Description

technical field [0001] The invention belongs to the technical field of resource development and utilization, and in particular relates to a method and system for preparing high-white and high-purity aluminum hydroxide by using solid waste such as fly ash and coal gangue. Background technique [0002] The coal combustion process of power plants produces a large amount of fly ash. Except for a small part that is partially utilized as raw materials for cement and building materials, most of the fly ash is stored, which not only occupies a large amount of land resources, but also seriously pollutes the environment. The alumina content in fly ash is generally 17-35%, and the aluminum content in fly ash can be as high as 40-60% in some areas. It is a very important non-traditional alumina resource and has a high value for extracting aluminum. Coal gangue is solid waste formed during the coal mining process and coal washing process, and its main component is Al 2 o 3 , SiO 2 , C...

AI Technical Summary

Problems solved by technology

[0003] In order to utilize solid waste materials such as fly ash and coal gangue at home and abroad, many processes for extracting alumina from fly ash have been developed, mainly including pre-desilication method and hybrid method, but the existing alumina extraction technologies have certain defects. It is characterized by high investment, high energy consumption, and high pollution. In addition, the use of solid waste materials such as fly ash and coal gangue also faces the problem that the content of each component in solid waste varies with the origin of the coal.

For example, the hybrid method requires high investment and needs to add a large amount of lime or limestone powder. The sintering temperature is generally 1200-1400°C, the sintering amount is large, and the energy consumption is high. 4-10 tons of silicon-calcium slag is produced, and the amount of slag is 1.5-3 times that of fly ash. This silicon-calcium slag is similar to the red mud of the sintering process in the alumina industry. How to consume and dispose of these new slags is facing greater difficulties

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