A numerical investigation into key factors controlling hard rock excavation via electropulse stimulation

Abstract

Electropulse stimulation provides an energy-efficient means of excavating hard rocks through repeated application of high voltage pulses to the rock surface. As such, it has the potential to confer significant advantages to mining and drilling operations for mineral and energy resources. Nevertheless, before these benefits can be realized, a better understanding of these processes is required to improve their deployment in the field. In this paper, we employ a recently developed model of the grain-scale processes involved in electropulse stimulation to examine excavation of hard rock under realistic operating conditions. To that end, we investigate the maximum applied voltage within ranges of 120–600 kV, to observe the onset of rock fragmentation. We further study the effect of grain size on rock breakage, by comparing fine (granodiorite) and coarse grained (granite) rocks. Lastly, the pore fluid salinity is investigated, since the electric conductivity of the pore fluid is shown to be a governing factor for the electrical conductivity of the modeled system. This study demonstrates that all investigated factors are crucial to the efficiency of rock fragmentation by electropulsing.

Keywords

• Electropulse stimulation
• High voltage breakdown
• Numerical modeling
• Drilling
• Thermo-mechanics