Lime desulfurization method used in aluminium oxide production

Abstract

A lime desulfurization method used in aluminium oxide production follows the principle that lime or lime milk is added into a sulfur-containing sodium aluminate solution to generate two calcium hydroaluminosulfate sediments, and sulfur impurities in the sodium aluminate solution are removed together with the sediments. The lime desulfurization method particularly comprises the following steps: diluting the sulfur-containing sodium aluminate solution with the molar ratio of 3:1 for 3-4 times with water, slowly adding lime milk of 15-20 g / L CaO into the sodium aluminate solution containing 20-30 g / L SO4<2-> ions under a stirring condition, performing purification to realize desulfurization, filtering the purified sodium aluminate solution, and recovering Al2O3 and NaOH. The lime desulfurization method has the following advantages: (1) the desulfurization efficiency is high, and loss of aluminium oxide is reduced; (2) the sulfur dissolution rate and the dissolution speed are high, and the alkali consumption is low; and (3) Al2O3 and NaOH are recycled, and the production cost is lowered. The lime desulfurization method is suitable for aluminium oxide manufacturers.

Description

Technical field: [0001] The present invention relates to alumina, in particular to a method for desulfurization in the alumina production process. Background technique: [0002] In the alumina production process, when the sulfur content of bauxite is too high, sulfur will accumulate in the sodium aluminate solution and adversely affect most of the production processes, such as dissolution, sedimentation, and evaporation, and even make the entire production process impossible. The harm of sulfur to Bayer process production is mainly manifested in the increase of alkali consumption, the deterioration of product quality and the increase of equipment corrosion. Therefore, high-sulfur bauxite has not yet been used economically and effectively. Solving the technical problems in the process of producing alumina from high-sulfur bauxite and expanding the available bauxite resources will greatly alleviate the trend of the utilization of bauxite resources and the rapid dilution of ore, wh...

AI Technical Summary

Problems solved by technology

By adding zinc oxide or blast furnace ash to the Bayer circulating lye to precipitate sulfur into ZnS, the sulfur can be completely removed, and the iron in the solution can also be removed, but the disadvantage is that the zinc-containing material is more expensive

[0003] In short, for high-sulfur bauxite, the above-mentioned desulfurization methods have made some progress in recent years, but they all have some shortcomings and limitations, and have not been widely used in production practice.