Study on Failure Characteristics of Stemming Structure on Iron Ore Under Blasting Load

Blasting tests on iron ore specimens with different stemming structures were carried out to quantify the internal fracture and damage characteristics of the specimens by means of computed tomography (CT) scanning, digital image processing and three-dimensional (3D) model reconstruction techniques. The results showed that the blasting load produced radial and circumferential cracks in the iron ore, mainly along the blast hole. Using the fractal theory to analyze the damage characteristics of the samples, the stemmed structure under blasting load produced more fractures than the unstemmed structure, with a maximum increase of 33.6% in internal damage. As the stemming material changed from weak (yellow clay) to strong (fine sand), the fractal dimension of the specimen spatial tended to increase after blasting, and the degree of damage increased, with the stemming of fine sand increasing the maximum damage to the three-dimensional spatial by 12.1% compared to yellow clay stemming. This further suggested that the strength of the stemming material was positively correlated with the size of the damage to the specimen. The damage characteristics of the different layers of iron ore specimens (surface, stemmed section, charged section) were consistent with those of the 3D spatial as a whole, with the smallest difference in damage to the charged section and the larger difference in damage to the stemmed section. In practical blasting projects, the findings of this paper are used to make full use of the explosive energy using a reasonable stemming structure to achieve better breakage results for iron ore. The research result is of great significance to engineering practice.