Haponenko I. Improving of efficiency of rock breaking by air void charges at the bottom of blast-holes at the iron ore pits.

The thesis is devoted to efficiency improving of bench rock blasting by blast-hole charges using a new, worked out by the author design with air void and reflector at the bottom part of a blast-hole at the open pit mining. The thesis presents the results of a detailed analysis of existing blast-hole design charges of explosives. It is established that existing design of blast-hole charges do not allow in full use the energy of strain wave to generate maximum zone of rock breaking especially at the bench floor. In this regard the thesis deals with the peculiarities of the process of rock breaking by blast-hole charges of various designs, the dependences of their dynamics from physical and mechanical properties of rocks are given, interconnection of crushing energy in the environment and the value of specific impulse of the blast is made. Based on the obtained theoretical results a new design of blast-hole air void charge of explosives at the bottom of the blast-hole is worked out. A distinctive feature of the worked out blast-hole design is blast energy concentration towards the bottom of the blast hole which in reducing a specific consumption of explosives providing high-quality bench floor optimum line and opens the possibility to eliminate over drilling. Its optimal parameters in blasting technological chain are defined. Conducted production research of the given blast-hole charge design in the conditions of Gleevatka open pit of PJSC "CGOK" demonstrated its high efficiency that became the basis for subsequent implementation. Industry - Mining (technical sciences).