Mine gallery driving cutter - uses preliminary support above and in front of cutter formed of anhydrite material

摘要

The cutter drives galleries in underground mines the zone excavated by the machine being consolidated progressively by a support. The zone in front of and above the excavation machine is consolidated by a preliminary support which can be rapidly placed in position, and the final support is only installed behind the machine. For the preliminary support, material can be projected hydraulically onto the gallery roof and walls, comprising natural anhydrite of grain size less than 0.2mm and in a proportion of up to 30%, and half-fired plaster. The latter is gypsum, and from 20 to 60% by weight with grain size up to 1mm.