Method for producing aluminium oxide and by-product silicon by low-temperature alkali digestion of low-grade bauxite

Abstract

The invention relates to a method for producing aluminium oxide and a by-product silicon by low-temperature alkali digestion of low-grade bauxite, and belongs to the technical field of aluminium oxide production. The method comprises the following steps: firstly, smashed low-grade diasporic bauxite and a circulating mother liquid are grinded to form a mineral slurry; secondly, a digestion reaction is performed enable kaolinite in the mineral to be dissolved, react and enter a solution, filtration residues are high-grade bauxite concentrate, and the high-grade bauxite concentrate is processed for produce aluminium oxide and low-alkali red mud by adopting a Bayer process; sodium aluminosilicate in a filtrate is subjected to desilication reaction, so that sodium-silicon residues, and a filtrate containing aluminium oxide, silicon oxide and sodium oxide are obtained; and finally, the filtrate is supplemented by sodium hydroxide, and the supplemented filtrate is used as the circulating mother liquid to return for preparation of the mineral slurry through grinding, and part of the sodium-silicon residues are used as a seed crystal to return to a desilication process, and the other part of the sodium-silicon residues are used to prepare silicon products such as molecular sieves. The method is a whole-procedure wet treatment process, aluminium and silicone are fully extracted from the bauxite for preparing the corresponding products, also alkali consumption in the red mud during the Bayer process is substantially reduced, the alkali content in the red mud is reduced, and recycle value of the red mud is improved.

Description

technical field [0001] The invention relates to a method for producing alumina by-product silicon products by low-grade bauxite alkali dissolution at low temperature, and belongs to the technical field of alumina production. Background technique [0002] my country's bauxite resources are relatively rich, but most of them are medium and low-grade bauxite, which has the characteristics of high aluminum, high silicon, and low aluminum-silicon ratio (A / S). For low-grade bauxite, in recent years, the alumina industry has proposed several desiliconization methods. [0003] One is the beneficiation Bayer method, which has the advantage of lower cost, but for some bauxite, due to the complex mineral composition and fine crystallization of minerals, it is difficult to dissociate monomers, plus some aluminosilicates (such as Kaolinite, oolitic chlorite, etc.), the physical beneficiation of bauxite is more difficult, and there are also disadvantages such as relatively low alumina rec...

Images