Method for producing aluminum oxide by high sulfur bauxite

Abstract

The invention discloses a method for producing aluminum oxide by high sulfur bauxite, which comprises the processes of raw material preparation, high-pressure digestion, settling separation and washing, aluminum hydroxide seed decomposition, aluminum hydroxide washing and calcination, and mother liquor evaporation. The high-pressure digestion process comprises a low-temperature section, a medium-temperature section and a high-temperature section; compressed air is fed into a high-temperature section reaction kettle in the high-pressure digestion process, so as to finally oxidize S2- in pulp into SO42-; and SO42- is combined in sodium-silicon slag in red mud and discharged with the red mud. By adopting the technical scheme, the concentration of negative bivalent sulfur in dissolution pulp liquid phase is obviously reduced, the concentration of thiosulfate in the dissolution pulp liquid phase is not increased obviously, the concentrations of negative bivalent sulfur and ferric oxide in circulating mother liquor are obviously reduced, the concentration of negative bivalent sulfur in fine liquor is obviously reduced, the concentration of thiosulfate is not increased obviously, the content of ferric oxide in the fine liquor is reduced, the contents of ferric oxide in aluminum hydroxide and aluminum oxide meet the primary standard of the national standard, and all production links return to normal.

Description

technical field [0001] The invention relates to a method for producing alumina from Bayer process high-sulfur bauxite. Background technique [0002] The reserves of diaspore-type high-sulfur bauxite in my country are at least 150 million tons, and the sulfur in the ore exists in the form of pyrite (FeSz), usually when the sulfur content in the ore is greater than 0.7% Known as high-sulfur aluminum ore. The process of producing alumina from high-sulfur bauxite is very difficult, and the sulfur in the ore enters the sodium aluminate solution in the form of negative divalent sulfur during the dissolution process. This leads to an increase in the iron content in the sodium aluminate solution and the product alumina. [0003] At present, the desulfurization technologies for producing alumina from high-sulfur bauxite at home and abroad mainly include: adding coal to raw materials for desulfurization, adding zinc oxide for desulfurization, flotation desulfurization, etc. But abov...

AI Technical Summary

Problems solved by technology

If the production technical conditions and operation are improper or the sulfur content of coal used for sintering fuel increases, the desulfurization effect will be poor; the cost of adding zinc oxide to desulfurization is high, and it is difficult to realize industrial production; the investment in flotation desulfurization equipment Large, high cost, need to be carried out simultaneously with flotation desiliconization

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