INNOVATIONS IN ROCK FRAGMENTATION AND FRACTURING - CREATING ACCESS FOR LEACHING

摘要

The application of in situ leach technologies to metal recovery requires new access creation methods due to the low permeability and different geology of the target formations. New technologies for rock fracturing and fragmentation have been developed recently with increasing requirements to extract ore from underground in novel ways. The target of the new technologies is to improve productivity, protect the environment, health and safety as reduce the usage of energy and water. Many of these of these technologies could be applied in hard rock recovery processes. In hard rock, fracturing is necessary for the lixiviants to contact enough ore to create larger recoveries. The mechanisms of fracturing have been known since the stone age and include direct pressure, indirect pressure, splitting, heating and cooling, often applied in combinations. The potential to apply these mechanisms for creating flow paths in the rock mass are considered. Opportunities for applying these mechanisms using new technologies are provided by advances in materials and knowledge. New methods for fracture development include cryogenic fracturing, microwaves and pulsed detonations. Additional challenges in application of these techniques for in situ recovery include the geological setting of the ore the in- situ stress and the extent of initial fracturing. The paper discusses two options for providing access to leach recovery. The first involving in situ operations with drill holes from surface. The second method being In Mine Recovery for marginal ores in existing mines by creating leach silos. A review of potential fracture methods for each, including the recent literature and patents is presented to provide an overview of current technologies for rock breaking. Practical applications from other mining operations such as cave mine preconditioning are considered as options.