ustification on safe parameters of drilling and blasting mining of sylvinite formations of unconventional thickness together with continuous mining of conventional formations in the mines of Verkhnek

In the conditions of the Verkhnekamskoe field of potassium and magnesium salts unconventional in terms of thickness sylvinite seams are involved in the mining. That requires methodological support and new technological solutions. One of the possible directions in the excavation of sylvinite seams of unconventional thickness is the use of drilling and blasting. A method for calculating the safe geomechanical parameters of the chamber development pattern was developed in order to justify the possibility of drilling and blasting excavation of sylvinite seams of unconventional thickness. The paper presents theoretical calculations for determination of the parameters of a chamber development pattern taking into account the requirements of current regulatory documents. That ensures geomechanical safety during drilling and blasting mining of sylvinite seams of unconventional thickness as well as during mining of sylvinite seams of unconventional thickness in combination with mashinery mining of seams with conventional thickness. Two options of drilling and blasting mining of sylvinite layers depending on the mining and geological conditions of development, are considered in the paper. The first option considers drilling and blasting excavation by the chamber pattern of one sylvinite seam of unconventional thickness. The second option considers drilling and blasting mining of an unconventional sylvinite reservoir together with a machinery mining of adjacent sylvinite layers that have conventional thickness. Minimum allowable size of the production chamber in the drilling and blasting mining of sylvinite seams of unconventional thickness, design and actual parameters of chambers and inter-chamber blocks are justified according to the requirements of regulatory documents. The procedure for calculation of sizes of the cleaning chambers in drilling and blasting mining and inter-chamber blocks in the joint excavation of sylvinite layers of conventional and unconventional thickness. The method for determination of safe parameters of blasting operations providing the permissible value of the fracturing zone in the soil and roof of the cleaning chambers mined by the drilling and blasting method is presented. Calculations have been performed to determine the fracture radius based on the calculation of explosion pulse and dynamic strength of the salt rocks. Determination of the allowable weight of explosion is done using the value of the displacement speed of the particles in the array. As a result of the studies performed, the safe parameters of drilling and blasting mining of one sylvinite layer with unconventional thickness by the chamber pattern and the sylvinite formation of unconventional thickness together with longwall machinery mining of conventional formation at the mines of Verkhnekamskoe field of potassium and magnesium salts