Prediction of maximum safe charge per delay in surface mining

Abstract

Various predictor equations have been proposed to determine the peak particle velocity (PPV), a function of distance (R) and maximum safe charge per delay (Qmax). PPVs calculated by using these predictor equations give results close to observed values in the field. However maximum safe charge per delay calculated using these predictors does not give a satisfactory result, because Qmax is determined by back calculations. So comparisons of Qmax values by direct statistical calculation and back calculation do not tally. This paper advocates the evaluation of Qmax by direct calculation (rather than back calculation). Predictor equations for directly calculating Qmax are proposed based on statistical analysis. Results were well correlated with observed values. Qmax was calculated by all predictor equations and compared to the proposed equations. The coefficient of correlation (r) was high for the proposed equation. The proposed equation may give a better prediction of safe charge as compared to the use of back calculation from general predictor equations. © 2005 Institute of Materials, Minerals and Mining and Australasian Institute of Mining and Metallurgy.