Practical evaluation of some coal-cutting theories using a continuous miner : Roxborough, F F; Pedroncelli, E J Min Engr, V142, N252, Sept 1982, P145–156

Abstract

As part of a major research programme in coalface mechanization, the South African Chamber of Mines has undertaken a comprehensive series of experiments in coal cutting using a Lee-Norse machine equipped with a special drum allowing four different levels of pick spacing, 50, 100, 150, and 200 mm to be investigated. Other modifications were made to the machine so that it could cut at drum speeds of 42, 35, 15 and 7 rpm and generate a much higher than normal sumping and shearing force capability at the cutting drum. The results of these experiments have shown that cutting efficiency improves markedly when operating at a large depth of cut, and that the optimum spacing for picks is between one and two times the depth of cut. This conforms well with laboratory and theoretical findings. However, the point-attack pick, which previously has been critized as an inefficient tool, was found in practice to be somewhat more efficient than the chisel-shaped pick at larger depths of cut, although its performance was generally inferior at shallow depths. (12 refs.)