A Hybrid Approach to Rock Pre-conditioning Using Non-explosive Demolition Agents and Hydraulic Stimulation.

This study presents a novel approach to rock pre-conditioning to promote the sustainability of low-grade ore mining applications such as in-situ recovery and cave mining. The proposed method involves a two-stage hybrid approach, utilizing soundless cracking demolition agents (SCDAs) to initiate radial fractures in a predrilled host rock, followed by hydraulic stimulation to extend the fractures. SCDA injection in the first stage creates multiple radial fractures around the injection well. However, the extent of fractures is limited to the near vicinity of the injection well. To overcome this limitation, the second stage involves the application of hydraulic stimulation to extend the initiated fractures, which produces a greater fracture density compared to pure hydraulic stimulation. The concept was assessed using a fully coupled hydro-mechanical discrete element model that simulated the hybrid fracturing method on crystalline rock at the grain scale. The results indicate that the proposed method can create a high density of fractures around the injection well. Additionally, we identify and evaluate the key factors affecting the performance of the proposed method, including rock mass heterogeneity, stress anisotropy, and pre-existing defects, providing valuable insights for further experimental design and execution. Overall, the study offers promising results for a potential solution to enhance the efficiency of low-grade ore mining through the hybrid rock pre-conditioning method. Highlights: A novel hybrid two-stage pre-conditioning technique for low-grade ore recovery using soundless cracking demolition agents and hydraulic stimulation. A fully coupled hydro-mechanical model in the grain scale using the discrete element method to simulate the hybrid pre-conditioning technique. The hybrid method produces multiple radial fractures around an injection well, regardless of in-situ stress anisotropy. The hybrid method reduces the risk of uncontrolled fracture propagation by lowering the breakdown pressure of hydraulic stimulation. [ABSTRACT FROM AUTHOR]