Analysis of blasted rocks fragmentation using digital image processing (Case study: Limestone quarry of Obajana Cement Company)

Purpose. Blasting is an important aspect of mining activities in which fragmentation is the key component that determines its efficiency. Fragmentation is the first result of blasting, and is directly related to the costs of mining. Methods. There are two basic methods for determining the degree of rock fragmentation, the direct and indirect methods. The direct method includes sieve analysis while the indirect method involves observational, empirical and digital image processing methods. The digital image processing method with the aid of Split Desktop software was used in this study, to analyze the size of fragmentation in Obajana limestone quarry. Two pits of similar line of operation were considered. Findings. In each of the pits considered, five muckpiles of blasted rocks after blasting with different blasting patterns were analyzed to study the fragmentation phenomenon. The F80 and F90 values from the Split Desktop image analysis for the 5×3 m and 4×3 m in Pit 1 and Pit 2 were approximately 87.96 and 96.20 cm; and 91.34 and 98.66 cm respectively. Also, the F80 and F90 values obtained from the Kuz-Ram model for the 5×3 m and 4×3 m of Pit 1and Pit 2 were 99.9967 and 99.9994 cm; and 99.9957 and 99.9993 cm respectively. The results of the Split Desktop were compared to the results of the Kuz-Ram experiential model. The values of F80 and F90 of the blasted rocks are very close to the crusher gape value of 1 m, which reduces the production costs, and that is an outcome practically realized for the two pits of Obajana quarry. Originality. The findings showed that the output obtained from the Split Desktop software which is a digital image processing method were in conformity with the Kuz-Ram experiential model which is based on empirical relationship. Practical implications. In conclusion, the results of the investigation have significant implications for the practical application. It gives more options to explore for rock blast fragmentation efficiency of the desired area.