Underground or Sub-Surface gold mining with Marc Lubaszka.
Underground mining consists of digging tunnels or shafts into the earth to reach buried gold deposits. Ore, for processing, and waste rock, for disposal, are brought to the surface through the tunnels and shafts.
Underground mining is used in Venezuela and can be classified by the type of access shafts used, the extraction method or the technique used to reach the mineral deposit.
Drift mining utilizes horizontal access tunnels, slope mining uses diagonally sloping access shafts, and shaft mining utilizes vertical access shafts. Mining in hard and soft rock formations require different techniques.
Other methods include shrinkage stope mining, which is mining upward, creating a sloping underground room, long wall mining, which is grinding a long ore surface underground, and room and pillar mining, which is removing ore from rooms while leaving pillars in place to support the roof of the room.
Room and pillar mining often leads to retreat mining, in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore.
Additional sub-surface mining methods include hard rock mining, which is mining of hard rock (igneous, metamorphic or sedimentary) materials, bore hole mining, drift and fill mining, long hole slope mining, sub level caving, and block caving.