Method for extracting aluminium oxide from coal ash

Abstract

The invention provides a method to extract aluminum oxide from a fly ash, and relates to a technological method which is to extract aluminum oxide from the fly ash and comprehensively utilize the residue after extracting aluminum oxide. The invention is characterized in the method which is as follows: ammonium sulfate is mixed into the fly ash to sintering, and the solid is dissolved to obtain the solution containing aluminum-ammonium sulfate; the solution is crystallized to form solid aluminium-ammonium sulfate; solid aluminium-ammonium sulfate reacts with ammonia gas to obtain aluminium hydroxide and ammonium sulfate, and aluminium hydroxide and ammonium sulfate are washed and filtrated to obtain solid aluminium hydroxide; solid aluminium hydroxide is calcined to obtain aluminum oxide; ammonium sulfate can be circularly used after being evaporated in the liquid phase. The ammonium sulfate which is used by the method of the invention is weak acidic, the corrosiveness on the equipment is small, and the ammonium sulfate can be used circularly. The whole process is easy to industrial application. The requirement of the corrosion resistance on the equipment is low. The amount of the residue is small which is beneficial to the comprehensive utilization of the residue after extracting the aluminum oxide.

Description

technical field [0001] A method for extracting alumina from fly ash relates to a process for extracting alumina from fly ash and comprehensively utilizing the residue after alumina extraction. Background technique [0002] At present, the production of alumina mainly uses bauxite as raw material, and the production methods of alumina are mainly alkaline method, including Bayer method, sintering method and combined method. In recent years, my country's alumina production has continued to grow rapidly and has become the world's second largest alumina producer. However, my country is a country with relatively poor bauxite resources. Currently, the nationally identified and inferred bauxite resource reserves have a significant impact on my country's alumina production. The degree of industrial guarantee is low, so the resource problem has become one of the main problems restricting the sustainable development of my country's aluminum industry. [0003] my country is a big coal c...

AI Technical Summary

Problems solved by technology

However, the main disadvantage of the acid method is that the reaction equipment used must be acid-resistant, and the recovery of waste acid is relatively difficult; secondly, when leaching alumina, many soluble impurities such as iron and magnesium in fly ash are also removed. Bringing into the solution, need to add post-processing process

These deficiencies will to a certain extent restrict the scale and social and economic benefits of acid extraction of alumina in fly ash

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