AN APPROACH TO DETERMINE AND PREDICT THE MEAN PARTICLE SIZE OF A MUCK PILE AFTER BLASTING ACCORDING TO SWEBREC PARTICLE SIZE DISTRIBUTION LAW BASED ON THE FORM OF SINGLE SPHERICAL CHARGE IN LABORATORY SCALE

In the manufacturing procedure at open-pit mines, tunnel construction or channel excavation activities, crushing rocks to a suitable grain size is one of the first technological steps, directly affecting the efficiency of the following steps in the overall process of drilling - blasting - loading - transporting. Currently, drilling-blasting is still an effective method in this field. However, controlling the blasting parameters to obtain a suitable mean particle size is still difficult for mining engineers and scientists. Hence, on a laboratory scale, this research carries out 6 blasting experiments based on the form of single spherical charge with a variety of powder factors but the same specimen condition, equations determining directly the Swebrec particle size distributions (PSDs) law are then established with the input data taken from sieve analysis, as a basis for establishing relationships among each pair of parameters such as the exponential coefficient of Swebrec PSD function b, the mean particle size Dtb, and the powder factor q. The results show that the obtained PSDs almost completely fit experiment data, coefficients of determination R2 for the entire data set are greater than 0.99. Each pair of relationships among b, Dtb, and q have R2 values greater than 0.98 with the addition of predictive significance. The calculations are modularized in Python programming language for use as a package. Compared to other existing methods, the final results can help quickly evaluate the quality of an explosion, appropriately calibrating explosion parameters to obtain the desired rock fragmentation without requiring knowledge of machine learning and statistics.