Abstract

Mining has been integral to human civilization, providing critical raw materials for technological, infrastructural, and industrial progress. Its importance has only grown, driven by both essential community needs and the demand for resources in emerging technologies, such as rare earth elements. Rock blasting is a primary technique in mining, valued for its cost-effectiveness and efficiency in breaking rock to access valuable minerals. Recently, the demand has intensified to optimize blasting to reduce downstream processing costs, conserve energy, and minimize emissions. Additionally, micro fractures would enhance the rock-fragments fluid permeability thereby enhancing desired chemical reactions during certain processing operations.

Efforts to evaluate blast-induced microfractures in rock fragments, aiming to enhance downstream mining efficiency, have been underway for a significant period. However, the lack of suitable tools to identify blast designs capable of generating favourable strains for microfracture formation in rock fragments during blasting has posed a challenge. The Field Trial and Error approach to identifying favourable blast designs is prohibitively costly and impractical for such a problem. An effective tool would be a blasting model that can simulate the full effects of all blast design parameters in a production blast, predicting strains and resulting microfractures in fragments. Conventional blast modelling that is based on first-principle of physics or empirical method in literature that focuses only on a few typical blastholes is inadequate, as the interaction among all blastholes, including delay timing and spatial explosive distribution, plays a crucial role in generating diverse strain distributions and fractures within the blasted overburden.

In recent years, a multiple blasthole fragmentation (MBF) model has been developed, based on easily measurable variables during blasting, which can effectively model the impact of all blast design parameters on rock fragmentation within the blasted volume. The MBF model has been applied to many mine sites for rock fragmentation improvement in Canada and the globe. Recently, the MBF model has been further developed to simulate the strains in the blasted overburden, in addition to modelling the fragmentation size distribution. The modelled strains are associated with fracture densities and intended to enhance downstream blast efficiency.

This paper presents the new capabilities of the model, including the underlying concepts and initial modelling examples. The MBF model allows estimating rock strains experienced during the blast, for various blast design parameters and geometries. The intent is to correlate these strains with created micro fractures in the blast rock fragments. Adjusting blast design parameters in the MBF model of explosive loading and delay timing allows blast optimization. Such optimizing would create desirable strains to enhance micro fractures within the rock fragments. This would improve mining operations by enhancing downstream operation efficiency, thus reducing costs.