One of the main purpose of accurate blasting in open pit mining is to achieve optimum rock fragmentation. The degree of rock fragmentation plays a significant role in order to control and minimise the overall production cost including loading, hauling and crushing. In the present paper, the application of a Number-Size (N-S) fractal model is intended to classify the blast fragmentation size in the Jalal-Abad iron mine, SW Iran, using GoldSize image analysis software for four blasting with the obtained result being compared with Kuz-Ram curves. To do this, the fractal dimensions via N-S log-log plots were generated based on the output of the GoldSize software. The results indicated that the fragmented rocks have a multifractal nature with four/five different fragmented populations in terms of size namely; the fine rocks with the size of less than 16 cm, Mean-fragment values between 16 and 45 cm, In-range between 45 and 70 cm and finally, oversize larger than 70 cm.