A method for producing wollastonite and alumina by hydrothermal method of fly ash alkali leaching and sintering

Abstract

The invention relates to a method for producing wollastonite and aluminum oxide through a fly ash alkali leaching and sintering hydrothermal method. The method comprises the following steps: (1) after fly ash is mixed with a chemical mineral separation solvent, performing chemical mineral separation treatment and washing to prepare a fly ash concentrate; (2) leaching the fly ash concentrate with a sodium aluminate solution; (3) preparing raw slurry; (4) sintering and preparing a clinker; (5) dissolving, separating and washing the clinker; (6) preparing xonotlite precursor raw slurry; (7) performing hydro-thermal synthesis to prepare a xonotlite precursor; (8) performing hydro-thermal synthesis to prepare xonotlite slurry; (9) preparing wollastonite. According to the method, the problems of high consumption of limestone, high energy consumption and large amount of slag in the prior art are effectively solved; by the comprehensive utilization of the fly ash, both the wollastonite and the aluminum oxide can be produced, the substitution of both silicon mineral resources and bauxite mineral resources is realized, soil and other resources are saved, and the large-scale economic production can also be realized.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of fly ash solid waste and mineral processing, and in particular relates to a method for producing wollastonite and alumina by a hydrothermal method of alkali leaching and sintering of fly ash. Background technique [0002] Some coal fields in central and western Inner Mongolia and northern Shanxi are rich in high-alumina coal resources, with prospective reserves of nearly 100 billion tons, equivalent to about 15 billion tons of high-alumina fly ash, which is equivalent to the current reserves of bauxite in my country More than 8 times of that, and the alumina content in some fly ash can reach 40~50%. This kind of fly ash is generally called high aluminum fly ash. Fly ash is the main solid waste from the perspective of power generation in power plants, but the alumina content in the high-alumina fly ash produced by the combustion of high-alumina coal can reach 35-45%, some even as...

AI Technical Summary

Problems solved by technology

However, my country's bauxite resources are quite scarce, and bauxite reserves only account for about 5% of the world's total reserves, and most of them are low-grade diaspore-type bauxite that is difficult to handle. Purchasing restriction policy, bauxite resource problem has become the biggest bottleneck for the sustainable development of my country's alumina and aluminum industry

[0005]Wollastonite produced by traditional technology is generally obtained by beneficiation of wollastonite raw ore, and it is also hydrothermally synthesized by firing limestone and silica powder from limestone. Resources and the environment are highly impacted

[0006] Existing various processes for producing aluminum hydroxide or aluminum oxide with high alumina fly ash all produce a large amount of silicon-calcium slag or silicon slag, and these silicon-calcium slag or silicon The large-scale and rational utilization of slag has become a huge bottleneck in the development of alumina production technology from various fly ash

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