Method for treating medium- and low-grade bauxite to produce metallurgical-level aluminum oxide by one-step andradite alkali heat method

Abstract

The invention relates to a method for treating medium- and low-grade bauxite to produce metallurgical-level aluminum oxide by a one-step andradite alkali heat method. The method comprises the following steps of S1, crushing and finely grinding the medium- and low-grade bauxite into mineral powder; S2, mixing and preparing the mineral powder, sodium ferrite or calcium ferrite, activated lime and circulating mother liquor into raw-material mineral pulp; S3, subjecting the raw-material mineral pulp to an alkali heat dissolving-out reaction; S4, diluting dissolved-out mineral pulp, and subjecting diluted liquor to liquid-solid separation; S5, introducing a carbon dioxide gas into a low-molecular-ratio sodium aluminate solution to carry out carbonation decomposition, so as to obtain crude aluminum hydroxide and carbonation-decomposed mother liquor; S6, subjecting the crude aluminum hydroxide to bayer-process treatment, so as to obtain the metallurgical-level aluminum oxide. According to the method provided by the invention, through adding the lime and the sodium ferrite or the calcium ferrite in a dissolving-out procedure, andradite-type slag instead of conventional dissolved-out slag is generated in the dissolving-out procedure; the dissolving-out rate of the aluminum oxide can be improved greatly; meanwhile, the metallurgical-level aluminum oxide is prepared; the method has the characteristics of being short in flow path and high in efficiency; the zero release of a material is realized.

Description

technical field [0001] The invention belongs to the technical field of alumina production, and in particular relates to a method for producing metallurgical-grade alumina by treating medium and low-grade bauxite with one-step alkali-thermal treatment of andandrite. 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). In addition, there are some aluminum-containing resources in my country, such as fly ash etc. With the decrease of ore grade, the cost of each alumina production process is gradually increasing, among which the Bayer process has the largest increase. According to the basic process and principle of the Bayer process, when the A / S of bauxite drops below 5, it will be difficult to process it with the Bayer process. For low-grade bauxite, the alumina industry has mainly adopted the follow...

AI Technical Summary

Problems solved by technology

However, after recent years of industrial practice, the increasingly exposed problems of the Bayer process have seriously hindered the normal operation of the production process and become a bottleneck for its continued promotion and development.

Images