THE CONSTRUCTION OF TWO SMALL-SCALE CAVING MINES AT LA ENCANTADA MINE, MEXICO

摘要

First Majestic Silver Corp.'s La Encantada Silver Mine is a producing mine with a capacity of 3,000 tonnes per day (tpd). The mine has been in production since the 1950's. The previous owners of the mine have employed post pillar cut-and-fill, with rock backfill material containing higher grades than the current mining cut-off grade. The La Encantada Silver Mine team is currently constructing two small-scale caving mines, San Javier breccia and La Prieta, to exploit both the high-grade material that is left as pillar and the economical backfill material. Sublevel and incline caving methods are currently being investigated for the two potential mining zones above, respectively. In order to meet the above objective, the mining levels of the new caving mines have to be developed in the rock pillar between the old mining levels. The poor rock quality of the development area, combined with a lack of geological and geotechnical information and the fact that different survey systems have been used throughout the mine's life, has made the construction process quite challenging. This paper discusses the studies and steps carried out to ensure the safe construction of these mines and to bring them into production within the approved budget and schedule.