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Aluminium chloride process for producing metallurgical-quality alumina from high-silica raw materials created by specialists of RUSAL's ETC and VAMI has a number of undeniable advantages over traditional methods of producing alumina from bauxite.
The raw materials in this case may be kaolin clays, deposits of which in the regions where RUSAL smelters are located are estimated at tens of billions of tonnes, and the proven reserves alone should be enough for more than 200 years of operation. In comparison with the production of alumina from nephelines, the acidic method, with the same electricity consumption, allows for an almost three-fold reduction in fuel consumption and total energy usage, as well as carbon dioxide emissions. The generation of mud, which is 2.5 tonnes per tonne of alumina (when producing alumina from nepheline – 6.7 tonnes), also significantly decreases, and the commercial yield of alumina increases to 92%.
These results, as well as the operating costs and capital expenditure, were confirmed during the production of alumina from kaolin clays at the RUSAL pilot mini-refinery in VAMI. When fine-tuning the hydrochloric acid technology, metallurgical alumina of the 'Sandy' quality was produced, as well as by-products with commercial prospects – caustic soda, pseudobemite, Si-shtof (amorphous silica). In the future, as global bauxite reserves become depleted, acid technology may become the main way to produce alumina on the planet.