Method for producing aluminum oxide and co-producing active calcium silicate through high-alumina fly ash

Abstract

The invention provides a method for producing aluminum oxide and co-producing active calcium silicate through high-alumina fly ash. The method comprises the following steps that: the high-alumina fly ash firstly reacts with a sodium hydroxide solution to carry out pre-desilication to obtain a liquid-phase desiliconized solution and a solid-phase desiliconized fly ash; lime cream is added to the liquid-phase desiliconized solution to carry out a causticization reaction, the resulting solid phase is active calcium silicate which is prepared through carrying out filter pressing, flash evaporation and drying to obtain the finished product; limestone and a sodium carbonate solution are added to the desiliconized fly ash to blend qualified raw slurry, then the blend qualified raw slurry is subjected to baking into the clinker, the liquid phase generated from dissolution of the clinker is a crude solution of sodium aluminate; the crude solution of the sodium aluminate is subjected to processes of first-stage deep desilication, second-stage deep desilication, carbonation, seed precipitation, baking and the like to obtain the metallurgical grade aluminum oxide meeting requirements. According to the present invention, the defects in the prior art are overcome; purposes of less material flow and small amount of slaggling are achieved; energy consumption, material consumption and production cost are relative low; extraction rate of the aluminum oxide is high; the calcium silicate with high added value is co-produced; the method provided by the present invention can be widely applicable for the field of chemical engineering.

Description

technical field [0001] The invention relates to high-tech resource utilization of fly ash, in particular to a method for producing alumina and co-producing active calcium silicate from high-alumina fly ash. Background technique [0002] With the increasing shortage of bauxite resources, the use of fly ash, coal gangue and other industrial solid wastes to extract alumina has attracted more and more attention. The extraction of alumina from high-alumina fly ash and other aluminum-containing resources has attracted more and more attention. For example, the Late Paleozoic coal seams and gangue in the Ordos Basin are rich in boehmite and kaolinite and other minerals, and the alumina content in the fly ash produced after combustion is as high as 50%, which is the same as that in medium-grade bauxite. Rather, it is a very valuable raw material for alumina production. According to statistics, the potential reserves of high-aluminum fly ash in the central and western regions of Inn...

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Problems solved by technology

Although these patents have considered the phase characteristics of fly ash and adopted the idea of ​​extracting silicon first and then aluminum to reduce energy consumption and improve element utilization, the white carbon black produced after silicon extraction currently has a small market share in China. , the disadvantage of limited dosage, and the production of white carbon black by the carbon separation method is difficult to control compared with the traditional acid method to produce white carbon black, the equipment is more complicated, and the cost is higher

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