Processing of Low-Quality Gibbsite-Kaolinite Bauxites

The results of studies on the processing of gibbsite-kaolinite bauxite are presented. The developed technology includes preliminary chemical activation and thermal transformation during enrichment to obtain a concentrate suitable for processing by the Bayer method. As a result of the chemical activation of gibbsite-kaolinite bauxite in a solution of sodium bicarbonate, a change in the phase composition occurs, which made it possible to improve the results of gravity enrichment with the production of a coarse-grained gibbsite fraction. The transformation of bauxite in the temperature range of 900-1000 degrees C is explained by the decomposition reactions of siderite, gibbsite, kaolinite, calcite, dolomite and sodium ferro-sulfide oxide, as well as the formation of sodium aluminosilicate, hematite, quartz and the chemically stable phase of corundum. The optimum firing temperature of bauxite is 950 degrees C, after which, as a result of alkaline treatment during chemical enrichment, the extraction of SiO2 into solution was 74.9%. A silicon modulus of enriched bauxite 10.9 units was obtained. As a result of the autoclave leaching of gibbsite-kaolinite bauxite after a two-stage enrichment, the maximum extraction of alumina into solution was 87.4%. The yield of red mud during the processing of bauxite enriched and calcined at 950 degrees C was 37.62%. During the autoclave leaching of bauxite without enrichment, the yield of red mud was 71%.

Automated summary

The results of studies on gibbsite-kaolinite bauxite processing are presented, including the use of preliminary chemical activation and thermal transformation to obtain a concentrate suitable for further processing. Chemical activation and temperature changes during enrichment improve the extraction of valuable components and lead to the formation of chemically stable phases. The optimized firing temperature and alkaline treatment result in high extraction rates and yield of red mud during processing.