St. Petersburg Mining University (St. Petersburg, Russia):

Dubovikov O. A., Professor, Doctor of Engineering Sciences, dubovikov_OA@pers.spmi.ru
Sundurov A. V., Postgraduate Student, s185092@stud.spmi.ru

Increased aluminum and, consequently, alumina outputs deplete the high-grade aluminum-containing bauxite resources. The silicon module is the main quality characteristic of bauxite, defining the recovery of aluminum oxide from the rock. The use of thermochemical conditioning of low-grade mineral raw materials is proposed in order to obtain bauxite concentrates with high silicon modules by reducing the amount of silicon dioxide in the concentrate. This will reduce the load on the energy-intensive sintering line and expand the applications of the less expensive Bayer hydrochemical method for processing bauxite raw materials. Roasting of raw materials, one of the stages for the technology proposed, is cheaper than sintering. Its purpose is to improve the liberation of silicon-containing bauxite minerals and ensure the subsequent transfer of the maximum amount of silicon dioxide into the solution at the desiliconization stage. For this purpose, the recovery of aluminum and silicon oxides into an alkaline solution was studied for the desiliconization stage at varying roasting temperatures. In order to minimize the sodium  hydroaluminosilicate generating reaction in the desiliconization process, a high liquid/solid ratio of over 100 : 1 was selected. This is an inadequate ratio for process operations, which may, however, be used to confirm the decomposition mechanism for silicon-containing minerals during thermal activation of bauxite from the Northern Onega deposits.

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