Mining Institute of the Ural Branch of the Russian Academy of Sciences, Perm, Russia

S. S. Andreyko, Head of laboratory, Professor, Doctor of Engineering Sciences
O. V. Ivanov, Senior Researcher, Candidate of Engineering Sciences
N. A. Litvinovskaya, Researcher, Candidate of Engineering Sciences, nlitvinovskaya@mail.ru
E. V. Lukyanets, Engineer

At the present time in mines of the Upper Kama potassium–magnesium salt deposit, the research is carried out toward improvement of process flow charts of the adopted roomand-pillar mining system. One of the trends in this regard is the use of the sequential approach to mining sylvinite seams AB and Krasny (KrII), with mining of seam KrII with backfill at first and then mining of seam AB. This article presents the results of the analysis into geotechnical conditions of gas-dynamic phenomena in the form of roof rock falls accompanied with gas emission, and the hybridtype events during the first-step mining of seam KrII at the Upper Kama potassium–magnesium salt deposit. The implemented analysis reveals the main causes of gas-dynamic phenomena in the first-step mining of seam KrII, including: the use of block of rooms with inter-room pillars and with wide pillars between the blocks of rooms; the undercutting and through-cutting of inter-room pillars; the absence of short-hole and long-hole preventive degassing drilling; the disagreement of the preventive degassing drilling parameters with the geotechnical mining conditions of seam KrII. For preventing gas-dynamic phenomena in sequential mining of seams KrII and AB, it is recommended to avoid wide rooms (blocks of rooms) and wide pillars; to avoid inter-room pillars wider than 1.5–2 m; to perform shot-hole and long-hole preventive degassing drilling at the parameters capable to ensure drainage of free gases in roof rocks at interfaces with clayey interbeds.

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