Modelos matemáticos utilizados na fragmentação de rochas com uso de explosivos: uma revisão

Abstract

Drilling and rock blasting operations add up to about a third of the average production costs in open pit mines. The main factors that corroborate these costs are related to the bad projection of the fire plane, involving the inappropriate sizing of the geometric parameters, the choice of explosives and, mainly, to studies related to the fragmentation of the rock mass, which can provide a prediction of the granulometric distribution of the pile formed from the dismantled material. The adequacy of fire plane parameters to obtain a pile with desirable granulometry can be performed using rock fragmentation models. In view of this, the present work aims to present a complementary review to the current literature on the mathematical models used to estimate the granulometric proportion of rock fragmentation with the use of explosives. For that, the following models were selected: Kuz-Ram, JKMRC (Julius Kruttschnitt Mineral Research Centre), KCO (Kuznetsov Cunningham Ouchterlony) and TCM (Two Component Model). The Cunningham model, Kuz-Ram, was the first set of equations used to estimate the granulometric distribution of the rock pile dismantled using explosives. However, this model is more efficiently applied to rock masses with good mechanical strength and does not accurately predict the amount of fines in the pile of fragments. The JKMR model emerged from the KuzRam and adapted the equations to accurately estimate the percentage of fine particles in the dismantled material. The KCO model adapted the Kuz-Ram to insert the fragmentation zones and a new uniformity equation to estimate the granulometric distribution. The TCM model made an adaptation of the KCO and inserted the presence of discontinuities in the rock mass as a parameter, which allowed a reclassification of the granulometric distribution to accurately predict the percentage of fine particles. In addition, the present work has a comparative analysism of three case studies that applied fragmentation methods in practical situations, in order to de- termine their efficiency. After the analysis, it was possible to conclude that the mathematical models used to predict rock fragmentation are of fundamental importance to increase the effi- ciency of the blasting stage, as it is reliable and presents relevant results, reducing the opera- tional and additional costs of this phase, such as dismantle secondaries.