The new approach to creating progressive and low-waste mining technology for thin coal seams

Abstract

The problem of mining low-thickness coal seams in the Western Donbas is described in the article. Technological, economic and environmental reasons reducing the effectiveness of traditional technologies for their development are analyzed in detail and the new progressive approach is proposed to solve it. Attention is paid to the importance of hard coal for Ukraine energy independence and thin coal seams, which is the lowest indicator among coal deposits exploited in the developed countries worldwide. The key role of the Western Donbas mines in the Ukraine coal mining industry development is shown, where coal seams with a geological thickness in a range of 0.55 – 0.80 m take more than 50% of coal reserves. It leads to coal clogging and rising of the further enrichment costs. The interrelation of mining, geological seam thickness, and wall rock undercut is established, as well as decade-long tendency out of seam size increase is evaluated. It appropriately correlates with the general tendency of a geological thickness decrease and it leads to an increase of total ash content. The sources are defined and the volumes of waste rock run from coal mine to the surface are quantified, where 80 – 90% are underground mine working development and wall rock undercut while longwall mining operations. The negative influence of the applied mining technologies for low-thickness seams is shown. Whereby existing waste rock dumps are additionally replenished annually by 3.0 – 3.5 million of large-sized coal enrichment wastes and transported back onto waste rock dumps for very high expenses. It is determined that three waste dumps are located near urban settlements, which increases the environmental fee for their placement in three times. The new approach for selective mining of low-thickness seams with rock undercut placement in the gob area is proposed and it is characterized by the addition to the mechanized support of horizontally-closed scraper backfilling conveyor with a tamping device for rock compaction, which reduces the mine rock output by 25 – 30%. The preliminary calculations of parameters and prospective economic efficiency of the proposed mining technology for low-thickness coal seams are carried out in case of one typical longwall face taking into account the mined rock transportation cost to coal-preparation plant and its enrichment, reducing the cost of mine working supports. Its technology is by 17% more cost effective, than traditional mining technology while rough coal ash content does not exceed 21%.