Process for producing sand alumina by Bayer precipitation process

Abstract

The invention discloses a pocess for producing sand alumina by Bayer precipitation process which consists of, charging seed crystal into refined aluminum oxide solution in one or two times for decomposition, separating the obtained decomposition product by grades, returning the seed crystal back to decomposition process, subjecting the aluminum hydroxide product to filtering, scouring, drying, and sintering to obtain the sand form aluminum oxide product.

Description

technical field [0001] The invention discloses a method for producing sandy alumina by seed separation by the Bayer method, which involves using diaspore-type bauxite as a raw material, and performing Bayer method seed decomposition to produce sandy alumina by using a hybrid process or a pure Bayer process method. Background technique [0002] The production of alumina in my country mainly uses insoluble diaspore bauxite as raw material. Compared with the easy-to-handle gibbsite bauxite widely used abroad, the process conditions and technologies There are large differences in indicators and so on. When dealing with diaspore type bauxite, higher alkali concentration and dissolution temperature are required. At the same time, in order to reduce energy consumption and improve decomposition rate, it is also required to have a higher concentration of alumina in the decomposed raw solution and a larger caustic ratio of the mother liquor; in order to To achieve the required decomp...

AI Technical Summary

Problems solved by technology

When dealing with diaspore type bauxite, higher alkali concentration and dissolution temperature are required. At the same time, in order to reduce energy consumption and improve decomposition rate, it is also required to have a higher concentration of alumina in the decomposed raw solution and a larger caustic ratio of the mother liquor; in order to To achieve the required decomposition rate, the required decomposition time is prolonged, so that the particle size and strength of the product are difficult to guarantee

Using diaspore as raw material to produce alumina, the existing production process adopts the Bayer method semen to add aluminum hydroxide as a seed crystal, maintain a relatively low initial decomposition temperature for natural decomposition, and the final decomposition temperature is low, and the produced Alumina has poor strength and fine particle size. After roasting, most of its products are powdery and intermediate alumina.

Compared with sandy alumina, powdery or intermediate alumina has a small specific surface area, poor dissolution rate in electrolytes and poor ability to absorb hydrogen fluoride, high fine particle content, low product strength, and particle breakage during transportation Seriously, a large amount of fine particles are produced, resulting in large flying losses