Environmental problems at the underground limestone Baltar mine, Sao Paulo, Brazil

Baltar mine is the largest Brazilian underground limestone producer. The mining method is sublevel longhole stopping, with empty stopes averaging 110 x 40 x 200 meters. The first production panel has main haulage levels up to 150 meters of depth and ventilation problems are minor and easily solved. Development of ramps and access drifts for the second panel, at depth of 300 meters or more, has generated environmental problems related to fresh air quantity, dust and thermal comfort conditions. An environmental data survey was carried out and results indicated that the old ventilation system could not support further deepening of the mine, and thus new fans, main and auxiliary, are be required.