Efficiency of Auxiliary Washing in Coal Enrichment Using Single-phase Heavy Media

The article considers the possibility of improving the quality (reducing ash content and increasing the calorific value) of coal used as fuel for energy facilities operating on the territory of the Russian Federation. It is proposed to improve the quality of solid fuel through the use of gravitational enrichment processes based on heavy-medium separation with subsequent auxiliary washing. Natural underground sodium chloride brines, bischofite, and wastewater from Na-cation exchange filters are used as heavy media in the processes considered. The possibility of using water of various mineralization levels as washing water during the auxiliary washing process is assessed. The use of demineralized water after reverse osmosis plants, water from the water supply system of the National Research University Moscow Power Engineering Institute (NRU MPEI), water from surface sources (water of the Yauza River), wastewater from Na-cation exchange filters, and waste heavy medium from the working area of a trough-type gravity separator (spent natural underground sodium chloride brines, spent bischofite, and highly mineralized wastewater from Na-cation exchange filters) is considered. In the course of evaluating the effectiveness, experimental work was carried out with enriched coal based on modeling the auxiliary washing process. The ash content was determined in accordance with the relevant regulatory documents before and after auxiliary washing with the test medium. The possibility of using demineralized water from reverse osmosis plants, water from the water supply system of the NRU MPEI, water from surface sources (water of the Yauza River), and wastewater from Na-cation exchange filters as a washing medium in auxiliary washing processes has been confirmed. The results obtained can be applied both in the development of energy facilities and in the operation of enrichment plants and energy technology complexes.