The fragment size of blasted rocks considerably affects the mining costs and production efficiency. The larger amount of blasthole diameter (ϕh) indicates the larger in blasting pattern parameters, such as spacing (S), burden (B), stemming (St), charge length (Le), bench height (K) and the larger the fragment size. In this study, influence of blasthole diameter, blastability index (BI) and powder factor (q) on the fragment size were investigated. First, the image analysis was perfomed and then the relation between each of X20, X50 and X80 with BI, ϕh and q as the main critical parameters were analyzed by multivariable linear regression (MLR) procedure using SPSS v.25 software. Relation between each of X20, X50 and X80 with the combination of adjusted BI, ϕh and q were obtained by MLR procedure with good correlations of determination (R2) and less root mean square error (RMSE) values. The developed models can be used as new relations to estimate the fragment sizes of blasted rocks.
