Normal pressure low temperature leaching production method for alumina

Abstract

The invention relates to a normal pressure low temperature leaching production method for alumina comprising the steps of, (1) subjecting the bauxite to extraction reaction in alkaline solution, filtering to obtain queous alkali and slags containing sodium aluminate, (2) subjecting the queous alkali to compression and cooling down for crystallization, filtering to obtain hydrated sodium aluminate coarse-grain and the filtrated stock solution, dissolving the hydrated sodium aluminate coarse-grain with water or diluted alkaline liquor, obtaining aluminum hydroxide through desiliconization operation, and calcining the obtained aluminum hydroxide.

Description

technical field

[0001] The invention relates to the field of production methods of alumina, in particular to a method for producing alumina at normal pressure and low temperature for processing insoluble diaspore bauxite. Background technique

[0002] Alkali process is used in the existing production of alumina, mainly including Bayer process, sintering process and its combined process. The sintering method is mainly used to process bauxite with a low aluminum-silicon ratio. When dealing with bauxite with a high aluminum-silicon ratio, its benefit is much lower than that of the Bayer process. The Bayer process mainly uses 200-300g / L NaOH aqueous solution to dissolve bauxite and then directly dilutes and desilicates the seeds to obtain aluminum hydroxide. However, when it is used to process the diaspore type bauxite that accounts for more than 98% of my country's bauxite resources, high temperature (235-280°C) and high pressure (3.5-6.0MP) operati...