Method for producing aluminum oxide by utilizing high-alumina fly ash

Abstract

The invention provides a method for producing aluminum oxide by utilizing high-alumina fly ash. The method comprises the following steps: 1) pre-desilicification treatment; 2) primary alkali dissolution reaction; 3) secondary alkali dissolution reaction; 4) crystallization of sodium metaaluminate; 5) seed precipitation decomposition of aluminum hydroxide; and 6) aluminum oxide product. After the pre-desilicification treatment is carried out on high-alumina fly ash, the dissolution processes of the aluminum oxide are conducted by two steps, twice alkali dissolution adopts different alkali concentrations, so that the problem that the prior art only adopts alkali dissolution once and has high requirements on the reaction conditions of temperature and alkali concentration and the like can be effectively solved, the aluminum oxide in the high-alumina fly ash can be fully dissolved, and the dissolution rate can achieve more than 92%.

Description

technical field [0001] The invention relates to a method for producing alumina by utilizing high-alumina fly ash, which belongs to the technical field of metallurgy. Background technique [0002] my country is the world's largest producer of alumina, and currently produces more than 40 million tons of alumina per year. But at the same time, my country's bauxite resources are relatively scarce, and bauxite reserves only account for about 7% of the world's total reserves, and most of them are difficult-to-handle diaspore mines. The problem has become the bottleneck of the sustainable development of my country's alumina industry. [0003] The reserves of high-aluminum fly ash produced by coal power generation in central and western Inner Mongolia and northern Shanxi in my country are abundant. The potential reserves of high-aluminum fly ash in the Zhungeer coalfield in Inner Mongolia alone reach 15 billion tons, which is equivalent to the current aluminum alloy in my country. T...

AI Technical Summary

Problems solved by technology

In recent years, various colleges and scientific research units in my country have actively carried out research on the new process of extracting alumina from high-alumina fly ash. The main processes can be divided into: pre-desilication-soda lime sintering method, acid method, ammonium sulfate sintering method Among them, the acid method has the disadvantages of serious corrosion of equipment and high impurity content in the product, making it difficult to produce metallurgical-grade alumina to achieve large-scale industrial production; the ammonium sulfate sintering method has a large slag phase flow rate and difficulty in recycling ammonia gas, etc. Disadvantages, there are no examples of industrial production; the limestone sintering method is similar to the soda limestone sintering method, and has the disadvantages of larger slag phase flow rate and higher energy consumption; the pre-desilication-soda lime sintering method is currently the only one that can realize industrial production However, this process has the problems of long process flow and high sintering energy consumption.

Images