Effect of charge load proportion and blast controllable factor design on blast fragment size distribution

Abstract

Blasting operation involves the use of a specific explosive quantity, detonated to fragment insitu and oversize rock block for particle reduction. Rock fragmentation size distribution has a direct influence on the proposed costs of mining one ton of the ore and the cost of run-off-mine processing. The focus of this study is on investigating the effect of charge load ratio and blast design parameters such as stiffness ratio, maximum instantaneous charge, and specific charge on rock fragmentation particle size distribution in dolomite quarry located at Akoko Edo state, South-west Nigeria. The 50% passing sizes (X50, m), 80% passing size (X80, m), and characteristic size (Xc, m) of blast results were determined using Wipware software. It was observed that the optimum mean size (X50, m), 80% passing fragment size (X80, m), and characteristic size (Xc, m) of rock depends strongly on the explosive bottom and column loading ratio, stiffness ratio, and specific charge. The regression analysis result reveals that the explosive specific charge and stiffness ratio influence the fragment size distribution with a negative correlation relationship, and the explosive bottom and column loading ratio has a positive correlation relationship with the blast fragmentation. Multivariate Regression (MVR) models were developed for the prediction of blast fragmentation sizes (X80, X50, and Xc) with R2 values of 0.76, 0.52, and 0.63 respectively. Based on the low correlation value obtained from the developed models, the proposed multivariate Regression (MVR) models are less suitable for the prediction of blast fragmentation particle size distribution.