Rock Fragmentation by High-Voltage Pulses
Résumé
Rock breaking is an essential operation in mining engineering as well as in the exploitation of natural resources such as geothermal, oil, and gas drilling. High Voltage Pulse Fragmentation (HVPF) has shown a possible lower specific energy, unlike the mechanical methods in hard rocks. An accurate understanding of the physical mechanism behind the HVPF process is required to optimize the competitiveness of this technique and encourage its deployment on the industrial scale. HVPF is realized by delivering a fast-rising voltage pulse of hundred kilovolts to a rod electrode in contact with a specimen, which rests on a grounded electrode plate. This paper presents the experimental results of two materials concrete and sandstone which is either dry or saturated. The specimens are loaded with 90 kV electrical discharge and single and multiple pulses. Small craters are formed on both sides of the dry and saturated sandstone specimens, while radial tensile cracks propagating from the channel along the boundaries of the aggregates are observed in concrete. A complete channel passing through the specimens and thus joining the two electrodes is observed. Likewise, the repetition of pulses exponentially increases the volume of the crater showing the cumulative effect of pulse repetition on the rock fragmentation process. These experimental
observations suggest that the discharge occurs most likely in a direct mode.
Domaines
Sciences de l'ingénieur [physics]
Origine : Fichiers produits par l'(les) auteur(s)