Application of thermal conditioning in foam separation of diamond-containing kimberlites

Abstract

The mechanism of the heat treatment effect on the surface condition and floatability of diamonds with a high concentration of hydrophilizing surface mineral formations is studied. By the method of X-ray photoelectron spectroscopy (XPS), it is found that when heated to a temperature above 65°C, the processes of thermomechanical destruction of diamond crystal concretions with rock minerals occur, ensuring cleaning of the diamond surface by 20–50 %. It is shown that when the medium is heated to 80–85°C, due to the removal of molecular and ionic forms of carbonic acid from the aqueous phase, the thermochemical dissolution of hydrophilizing films on the surface of diamond crystals is intensified. Heat treatment at a temperature higher than 80°C for 60–120 s allows achieving diamond purification to a degree of 67–90 %. The developed technology of thermal conditioning of the pulp in the cycle of foam separation of diamond-containing material includes its treatment with superheated steam at a temperature of 105–110°C, which allows achieving the required heating intensity (80–85°C), ensuring effective cleaning of the surface of diamond crystals from hydrophilizing mineral formations and, accordingly, increasing their flotation activity. At the same time, the consumption of flotation reagents is decreased by 10–12 % and the circulation of industrial products in the foam separation cycle is reduced. The technology of thermal conditioning in combination with electrochemical conditioning of recycled water of the foam separation cycle provides the increased recovery of diamonds in the final concentrate by 3.9–5.1 %. The developed technological mode of the diamond-containing material preparation for the foam separation process has passed pilot testing and is recommended for industrial application at processing plant No. 3 of Mirny GOK, ALROSA.