Moderate blasting technologies: Experience and prospects for introduction in Polyus mines

It is commonly known that rock fragmentation by blasting is the most economically efficient method to prepare large volumes of rock mass to excavation and handling. The drilling and blasting technology accepted by a mine governs both rock fragmentation quality and mining safety connected with slope stability. Therefore, optimization of drilling and blasting is an objective calling for the effective blast design and control. This article presents the main principles and methods of moderate blasting implemented at Polyus company towards minimization of impact on pit walls and benches. The main point is stagewise reduction of the dynamic effect exerted by blasting on rock mass when approaching the ultimate pit limits. Polyus company initiated the far and wide review and introduction of the best international practices for improvement of blasting operations near the ultimate pit limits. The article describes the activities undertaken within implementation of projects on drilling and blasting technology justification and improvement to enhance stability of pit walls and, as a consequence, to reduce geotechnical hazards. As a complimentary measure to abate seismic effect of explosions on adjacent rock mass, the nonelectric blasting is replaced by electronic blast initiation systems with more accurate delay intervals, which almost nullifies probability of simultaneous ignition of two or more charges and ensures, thereby, the acceptable and seismically safe modes of blasting of large rock blocks. Furthermore, the introduction of the electronic blasting cardinally changes the approach to blasting order and sequence per intervals in blast holes depending on the current task within a block to be blasted.