Method for extracting aluminum oxide from fly ash by one-step process

Abstract

The invention relates to a method for extracting aluminum oxide from fly ash by a one-step process. The technique for extracting aluminum oxide from fly ash by an acid-process / alkali-process has the defects of long technological procedure, complex equipment and poor economic performance, and restricts the large-scale application. The method comprises the following steps: mixing fly ash and potassium sulfate in concentrated sulfuric acid to carry out granulation; roasting for activation at certain temperature; dissolving out the solid in water or sulfuric acid to remove solid residues; removing the impurity iron from the solution by a jarosite process; crystallizing the solution to obtain solid potassium aluminum sulfate dodecahydrate; roasting the potassium aluminum sulfate dodecahydrate to obtain aluminum oxide, potassium sulfate solid and sulfur trioxide gas; and washing the solid phase, and filtering to obtain the aluminum oxide product. The potassium aluminum sulfate solid is obtained by cooling crystallization, thereby lowering the energy consumption; the impurities can be effectively removed in the crystallization process, thereby reducing the investment for the impurity removal system; and the potassium sulfate and sulfuric acid can be recycled, so the economic benefit of industrial production is high.

Description

technical field [0001] The invention belongs to the technical field of fly ash treatment, in particular to a method for extracting alumina from fly ash in one step. Background technique [0002] High-aluminum fly ash is a new type of fly ash that has appeared in the central and western regions of Inner Mongolia with the development of coal resources in western my country and the construction of large-scale thermal power plants in recent years, and its Al2O3 content can usually reach about 50% , which is equivalent to the content of Al2O3 in the middle and low grade bauxite in my country. [0003] In recent years, with the rapid development of my country's aluminum industry, the shortage of bauxite and alumina supply has become increasingly prominent. At present, my country's bauxite reserves are only about 2 billion tons, and high-quality bauxite resources are relatively scarce, and most bauxite and alumina need to be imported from abroad. In order to meet the development ...

AI Technical Summary

Problems solved by technology

The alkaline method mainly follows the method of extracting alumina from bauxite. This method has a long process flow, and the amount of residue produced after extracting alumina is several times that of fly ash, which does not meet the national environmental protection requirements; compared with the acid method The process flow is short, but the hydrochloric acid corrodes the material of the equipment seriously, and the corresponding equipment investment is relatively high; if the evaporation operation is used in the acid system, the energy consumption will be greatly increased, and the economy is not high