26 / 2020-03-01 11:14:12

The use of soundless chemical demolition agents as an alternative to rock breakage

Soundless Chemical Demolition Agent,Explosive-Free Method,Hard Rock,Underground Mines

The method of drilling and blasting with explosives is widely used in rock fragmentation applications in the mining industry for mine development and ore production. However, the use of explosives is associated with rigorous safety and environmental constraints as blasting creates toxic fumes, ground vibrations and dust. This study is conducted on Soundless Explosive-Free Chemical Demolition Agents (SCDA), a more environmentally friendly method for rock breakage and a potential replacement of explosives. SCDA are cementitious powdery substances with quicklime (CaO) as primary ingredient that expands during the moist curing process which results in high expansive pressure if this CaO hydration reaction occurs in a confined condition. More specifically, this method of rock fragmentation works by means of injecting the SCDA into a borehole of a rock mass; where the resulting crystallization pressure generated by the production of calcium hydroxide crystals creates an effective fracture network in the confined rock mass around the borehole. The use of SCDA as an explosive-free method is on the increase considering the need for non-violent and pollution-free methods for breaking rocks in populated areas. Presently, SCDA are used for rock fracturing in urban areas, rehabilitation projects, reinforced concrete cutting, granite and marble quarrying and excavating. Due to the negative impact of blasting in mining operations, it is crucial to develop a safe method to fracture rock in underground mines when blasting is not a desirable method for fracturing. However, the presence of high in-situ stress in underground mines could limit the initiation and propagation of rock fractures. While this is true, a few parameters can be varied and optimized and potentially overcome high in-situ stresses. The following paper will discuss work done by McGill University to optimize the performance of SCDA by modifying the borehole geometry, the use of additives and the development of innovative borehole pattern. The effective use of SCDA for further applications is discussed and extensive research on its performance in high confinement conditions is currently underway. This work is part of a multi-phase project that ultimately aims to develop a sound methodology for the rock fragmentation in underground mines with SCDA.