Influence of stope type and cablebolt reinforcement on unplanned ore dilution

摘要

Unplanned ore dilution has a direct and large influence on the cost of a stope, and ultimately on the profitability of a mining operation. An important, sometimes overlooked, parameter affecting unplanned dilution is the local stope setting within a tabular blasthole mining sequence. Depending on its placement within the planned mining sequence, a stope may be bound by rock on both side walls and above (a Primary stope), or it may have backfill on one or both side walls (a Secondary stope). Five stope-type categories were identified, based on their setting within the orezone mining sequence. Relationships between hanging-wall dilution and stope type were examined and compared, with parametric three-dimensional numerical modelling studies and case studies. For the case study, a comprehensive database was established from sequentially mined long hole stopes. The results demonstrate that the severity of unplanned hanging-wall dilution differed according to stope type and stope dimension. The case study also provides insight on the role that cablebolts installed in the stope hanging-wall play to control ore dilution by illustrating relationships between measured hanging-wall overbreak, cablebolt orientation and stope type.