# Blasting Fragmentation Study Using 3D Image Analysis of a Hard Rock Mine  
[PERSON]  
1 Vale S. A., Porto de Tubara, Vitoria 29090-900, ES, Brazil; [PERSON]@vale.com1 Instituto Tecnologico Vale, Ouro Preto 35400-000, MG, Brazil; [PERSON]@itv.org1 Vale S. A., Serra de Esmerli, Ithabir 35900-900, MG, Brazil; [PERSON]@vale. the possibility of using artificial neural networks, for example [4; 6]. Via the use of neural networks, it is possible to delimit and optimize the fragmentation induced by explosives, whereby, according to several bibliographies, studies about these analyses are difficult to find [6]. It is worth mentioning that blasting via explosives presents events of positive and negative impacts, and through the execution of planning, and when executing it, it tends to fragment the rock, through the development of cracks in the surrounding rock and the release of heat, energy, pressure, and stress waves [4]. The mishandling of these explosives can generate undesirable effects such as overpressure, ground vibration, flyrock, noise, heat, dust, and counter-resistance [4]. Through the development carried out by several researchers, mainly due to flyrock, the relationship between the maximum distance of this parameter as a function of the hole diameter, shape, and velocity coefficient of the rock to be dismantled was observed. Figure 1 presents a schematic summary of the drilling and blasting operations. Given the observations in Figure 1, the complexity of the analysis on the experimental procedures according to the blasting is verifiable, being the necessary techniques that help to gain a better perspective of the process, as is the case for the generated fragments. In this case, the fragmentation generated can be improved and optimized by observing the parameters used and via evaluation using the fragmentation model, generated by software, as in the case of PortaMetrics. During blasting via explosives, material fragmentation can occur due to the formation of new fractures, the presence of in situ blocks that must be released from the rock mass, or the fragments generated by the extension of the in situ fractures combined with the new fractures [4]. By considering the energy efficiency of the explosive, during the explosion, the rock mass is fractured by high-pressure gas, causing a tensile stress field and the formation of cracks that develop and expand, thus rupturing and breaking the rock [5]. The application of a suitable explosive should be considered according to the rock's tensile stress and uniaxial compressive strength to fracture and fragment the rock into blocks of suitable sizes. In addition, the fragmentation of the rock mass directly influences the operating costs, observing the calibration of transport, crushing, excavated materials, and other processes [6]. The programmed release and control of explosive energy during blasting is performed by adjusting the departure angle at the detonation of the explosive charge. This angle is determined by the relationship between the burden and spacing; consequently, the explosive energy and the level of fragmentation of the rocks are controlled by adjusting these parameters [7; 8]. Additionally, the hole diameter determines the mesh size (burden x spacing); therefore, for holes with smaller diameters, smaller spacings generate smaller fragment sizes than blasts with larger hole diameters and spacings. To contribute to fragmentation optimization, in blast planning, some parameters can be modified, such as the hole diameter, spacing, explosive amount, explosive type, stemming material size, and type [3; 9]. The quality or degree of fragmentation of blasting has been evaluated by indicators of blasting performance, such as the granulometric distribution of the blasting material [1; 10; 11; 12], the excavation time and productivity of shovels [13; 14; 15], and the loading time  
Figure 1: Schematic representation of operations during blasting.