Wider longwall faces may not be better

Synopsis Newstan colliery, New South Wales, was confronted by two problems that had a significant effect on both the immediate and the long-term viability of the business. The first was periodic weighting and the second was windblast. For the operation to remain as a longwall mine 'management plans' had to be written and applied to protect the safety of employees and ensure its commercial success. Strata control problems on the longwall face, manifested as periodic weighting, forced a reduction in face length. The results of this were a great improvement in face conditions and productivity but also the onset of windblasts. Methods were developed to predict the windblast events, monitor their intensity and protect the workforce from their effects. Subsequent face lengths were marginally increased in an attempt to minimize the windblast problem without a return to the destructive conditions associated with excessive periodic weighting. The experiences and methodologies adopted to deal with these conditions are described.