Numerical modelling of ore dilution in blasthole stoping

The paper presents the results of a study of the factors causing stope wall overbreak or ore dilution in a blasthole stoping environment. A series of three-dimensional numerical models are developed and analyzed to examine the effect of mining depth, in situ stress as well as stope geometry and orientation on stope wall overbreak. A characteristic orebody and mine design configuration is adopted and used as a basis to carry out comprehensive model parametric study, from which a simple, graphical design tool is derived for the prediction of stope overbreak. It is shown that stope overbreak is significantly affected by the stope aspect ratio and the orientation of major principal in situ stresses with respect to the stope. The methodology presented in this paper can be adopted to develop mine-specific design tools for the estimation of ore dilution associated with a proposed mine design. This can be extremely helpful in the process of underground mine planning and optimization.