Method for extracting aluminum oxide from coal gangue and co-producing active calcium silicate

Abstract

The invention provides a method for extracting aluminum oxide from coal gangue and co-producing active calcium silicate, and relates to the technical field of producing aluminum oxide and the active calcium silicate. The method comprises the following steps of: grinding coal gangue, and roasting and activating the ground coal gangue; performing alkali soluble desilication of coal gangue clinker to obtain desilication coal gangue and solution of sodium silicate; performing causticizing reaction of the solution of sodium silicate to obtain water-containing calcium silicate and solution of sodium hydroxide, and drying the water-containing calcium silicate to obtain micro powder of active calcium silicate; adding limestone and solution of sodium carbonate into the desilication coal gangue, and ball-grinding the mixed solution to obtain raw slurry; dissolving out the clinker which is obtained by roasting the raw slurry with water to obtain crude solution of sodium aluminate and silicon andcalcium residues, wherein the silicon and calcium residues can be used as cement raw materials after post-treatment; performing deep desilication of the crude solution of sodium aluminate to obtain the purified solution of sodium aluminate; feeding CO2 into the purified solution of sodium aluminate to obtain aluminum hydroxide and solution of sodium carbonate; and calcining the aluminum hydroxideto obtain the aluminum oxide products. The method has the advantages of simple process, low production cost, low energy consumption and little consumption of raw materials; in addition, by the method, two kinds of silicon-containing byproducts are simultaneously produced, and no waste is generated.

Description

technical field [0001] The invention relates to the technical field of alumina co-production active calcium silicate production, in particular to a method for extracting alumina co-production active calcium silicate from coal gangue. Background technique [0002] Coal gangue is the solid waste with the largest discharge and stacking volume in my country at present, causing great environmental pollution and waste of resources. The mineral composition of coal gangue is mainly kaolinite, in which alumina and silica are relatively high, and it is a potential mineral resource. With the country's increasing demand for metallurgical-grade alumina and the decreasing reserves of bauxite in my country, aluminum-containing mineral resources such as fly ash and coal gangue produced by industrial production are used to replace natural bauxite to produce alumina, etc. Industrial products, and the formation of a coal-electricity-metallurgy circular economy industrial chain, has increasingl...

AI Technical Summary

Problems solved by technology

The above three technical patents are all alkali methods. Due to the high silica content in coal gangue, the direct extraction of alumina requires a lot of alkali. Although the patent application number 200710133214.6 produces silicic acid as a by-product, the process is very cumbersome and economical.

The Chinese invention patent application number is 200410062965.X "a process for producing alumina", which discloses the activation and pre-desilication of kaolinite, fly ash and other raw materials in advance, and then uses limestone self-crushing and sintering method to mix and roast, carbonic acid Sodium dilute alkali solution leaching, leaching solution complexation reaction purification, carbonization to obtain aluminum hydroxide, and then high-temperature roasting into alumina, this invention firstly carried out pre-desilication, which reduced the consumption of alkali, but did not remove the The silicon dioxide is utilized, resulting in a waste of resources. In addition, the temperature of kaolinite roasting activation and limestone self-crushing and sintering in this invention is relatively high, and the energy consumption is relatively large.

Images