1. Sintering method for processing of high silicon bauxite

As it is known, the Bayer's method - the processing of bauxite into alumina - was discovered in Russia at the end of the 19 century. The method was developed in the works of many Soviet and foreign scientists. The Bayer's method is designed exclusively for processing high quality bauxite into alumina. At leaching bauxite, aluminum passes into the solution in the form of complex hydrated ions, silicon in the form of aluminum-silicon complexes. When the pulp is diluted, sodium hydro aluminosilicate precipitates, and alumina is isolated from the resulting solution. Bayer's method allows to extract only alumina from bauxite, while the technological scheme is quite simple, therefore, the improvement of this method did not introduce any significant changes in its technology. For the processing of low-quality bauxite for alumina, the method of sintering a wet batch consisting of bauxite, limestone and soda is used. To reduce the cost of the process of obtaining alumina from low-quality bauxite, a number of authors suggested using sodium sulfate instead of soda and limestone. A continuous process of sintering a mixture of bauxite, coal and Na₂SO₄ in a rotary tube furnace, followed by the decomposition of the sinter and obtaining alumina, is proposed.