Studies of halopelite content in the B-V rock salt layer of the Verkhnekamsk potassium-magnesium salt deposit

The paper presents the results of studying halopelite content in the B–V rock salt layer in conditions of the Verkhnekamsk potassium-magnesium salt deposit in terms of gas-dynamic hazard during mining of the AB potassium layer. Presence of halopelite bands in the interformational B-V rock salt layer is considered as the factor which causes reduction of both rock tensile strength and cohesion between individual rock layers in the roof of the mine workings that leads to its intensive exfoliation. In case of free gas accumulation or its infiltration from the enclosing rocks into the formed voids this can cause gas-dynamic phenomena, i.e. the roof rocks collapse accompanied by gas emission. Forecasting of the gas-dynamic hazards is extremely important both in mining of potash beds and in the development of oil and potash deposits that coincide laterally. In the course of the research, the content of halopelite within the B-V rock salt formation was taken into account using such a quantitative indicator as the content of water insoluble residue (IR). Analysis of statistical dependence of insoluble residue content as a quantitative characteristic of halopelite content in the B–V formation with the other formation characteristics such as calcium sulphate content, formation thickness and absolute roof elevation was performed. The regression equations were obtained that characterize the correlation relations between the IR and CaSO4, IR and Hcr with regard to the three studied options. Analysis of correlation coefficient values was executed between the IR by CaSO4, as well as the type of the regression equations for free and angular members.