Experience of Longwall Face Support Selection at RAG American Coal Company

摘要

At longwall faces, a hydraulic powered roof support with insufficient capacity often results in excessive roof convergence and thus roof failure or falls, or its structure damage under intensive roof activity; and an improperly designed support configuration may create roof control problems in the unsupported area between the canopy tip and the faceline due to a great tip-to-face distance or floor control problems due to the high toe pressure on the mine floor. However, a heavier-than-required roof support can dramatically increases its cost. Therefore, the selection of longwall face supports for a specific mining and roof condition is technically and economically critical for mine operations. The experience obtained from the RACC's (RAG American Coal Co.) longwall operations shows that a properly selected or designed roof support can not only provide a better roof control, but also has less maintenance work and a longer service life. The process of selecting longwall face supports for a specific mine site at RACC involves the following procedures: 1. Determination of the roof load demand on a face support, 2. Analysis of the resultant force on a face support, and 3. Selection of longwall face supports. At RAG American Coal Company, three methods have been used to determine the roof load demand on a face support. They are the Roof Shear Angle, Beam, and Neural Network methods. This paper tries to explain each method in detail and summarize our findings in the process of longwall face support selection.