Technology for producing aluminium oxide

Abstract

A process for preparing aluminium oxide features that the kaolinite and powdered coal ash are predesiliconized to make the Al-Si ratio is greater than 4, the self-breaking sinter method is used, the diluted solution of sodium carbonate is used for extracting, and the complex reaction is used for purifying. The pure CO2 gas generated by sintering and NaAl2O3 solution take part in carbonizing reaction to generate aluminium hydroxide. Changing the crystalline structure of aluminium hydroxide can obtain aluminium oxide.

Description

Technical field: [0001] The invention belongs to an alumina production process. Background technique: [0002] The traditional method of producing alumina is to use low-silicon and high-alumina bauxite (aluminum-silicon ratio ≥ 4) as raw material to produce it by Bayer method or traditional sintering process. Domestic bauxite reserves are decreasing year by year, the grade is declining, and the production cost is getting higher and higher. The traditional sintering method is to mix and calcine bauxite, limestone, coal and caustic soda together in proportion. The clinker is in the form of a hard block. When leaching, it must be broken first and then leached with water. The disadvantages are that caustic soda is corrosive to equipment, the firing temperature is high, the purity of the leachate is low, the process is complicated, the cost is high, and industrial waste residues pile up like mountains, polluting the environment. [0003] In recent years, there is a new calcinat...

AI Technical Summary

Problems solved by technology

Its technical core is "five-stage preheating and decomposition outside the furnace, coal powder calcination, special cooling equipment for rapid cooling, integrated with power plants and boilers, waste heat utilization, and silica slag production of cement". Its disadvantages are large investment and long process. There are too many process links and high cost. When the aluminum-silicon ratio is ≤1, the output of alumina is less, the output of cement is more, and the positions of main and by-products are reversed.

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