Preliminary Chemical Activation of Ash Waste with Release of Carbon Concentrate

Abstract

Research has been carried out to obtain carbonaceous concentrate from ash from the combustion of Ekibastuz coals by the flotation method. To increase the efficiency of flotation, a preliminary chemical activation of ash in a sodium bicarbonate solution was used, which made it possible to change the phase composition and mineral structure. Upon activation, the phases of aluminum silicate-silymanite and hedenbergite disappeared, changes occurred in mullite towards a decrease in the content of silica in it, the content of free silica increased from 8.7 to 36.1 %, and the calcite phase appeared. As a result of studies, it was determined that the optimal temperature of chemical activation is 150 °C, a further increase in temperature leads to insignificant changes in the phase composition. At a temperature of 150 °C, phase transformations in ash are completed with a duration of 60 - 90 min. After chemical activation of the ash, the carbon content in the carbonaceous concentrate obtained during flotation doubled. The richest carbonaceous concentrate with a carbon content of 52.9 % was obtained using kerosene and MIBC (Methylisobutylcarbinol).