Change in the phase composition of low-quality bauxites as a result of chemical activation

Abstract

As a result of separation of a fine fraction of gibbsite-kaolinite low-quality bauxite from the Krasnogorsky deposit, it is possible to increase its silicon module. When bauxite is chemically activated in a solution of sodium bicarbonate, the fine fraction is effectively separated from the large one and the phase composition changes – the calcium silicate phase disappears and the calcite phase is formed. With an increase in the activation temperature, the content of kaolinite and siderite decreases, the content of quartz and hematite increases. Studies have shown that at chemical activation temperatures of 120 oC, lasting more than 120 minutes and 200 oC, lasting more than 40 minutes, a dawsonite phase is formed in bauxite, which compacts the mineral structure. When determining the mode of chemical activation, it is necessary to take into account the negative possibility of the formation of dawsonite.