Methods for froth flotation testing of hard coal

Abstract Coal sludges are the smallest fraction of post-mining waste. Their grain size is less than 1 mm, and most grains have size below 60 μm. These wastes are mainly separated from the water-sludge circulations of the mines. Coal sludges are generally characterized by worse quality parameters in relation to the coal grades produced by mines. The fight against smog and the more stringent provisions in this area make it possible to monitor and control the quality of solid fuels, with particular emphasis on fuels directed for use in households and combustion plants with a rated thermal output of less than 1 MW which eliminated from the municipal and living market the coal sludges and post-flotation wastes containing less than 85% of hard coal, which are nuisance materials in the development process and their separation from the water-sludge circulation and dewatering requires many technological operations. The publication presents results of laboratory tests on the determination of conditions and possibilities of coal recovery from thermal coal sludges with an ash content of about 64%, using the froth flotation method. The experiments were conducted using a single operation method (fractional flotation) and a multiple operation method (main flotation, cleaning flotation). The tests were carried out using three types of the flotation reagents: standard (reference): ON MBIC (mixture consisting of diesel oil ON and 2-ethylhexanol OKT), specialized: Centroflot and proprietary: Klim III (non-ionic surfactants, auxiliary agents in a form of block copolymer of propylene and ethylene oxide and wetting additives, 2-ethylhexanol and a mixture of dioxane alcohols) to obtain the optimal concentrate.

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