Impact of the drilling and blasting parameters on the ore drawing losses: a physical modeling study

This study investigates the impact of the drilling and blasting parameters on the operational losses when using the mining methods of ore and host rock caving. The relevance of the study is associated with the need to justify the blasting parameters that would ensure a reduction in operational losses during ore drawing from below the caved rocks with account of the vertical variations of the ore grade within the ore body. The research was carried out based on physical modeling using a test-bench at a scale of 1:50 with copper-nickel ores and host rocks. The particle size distribution of the simulated rock mass was determined using the Kuznetsov–Rammler method. A series of six laboratory experiments was conducted for different particle size distributions. The results show that an increase in the mean particle size in the range of 193–433 mm leads to an increase in operational losses during ore drawing from 54% to 65%. It is shown that coarser fragmentation negatively affects extraction of the upper part of the ore body, which is characterized with a higher metal content. The obtained results confirm that the drilling and blasting parameters determine not only the rock fragmentation process, but also have a significant effect on the operational losses and the grade of the mined rock mass.