Dewatering of Ultra-fine Coal

Compares labour intensive mechanised drill and blast underground mining with capital intensive bord and pillar using continuous miners, and adds the option of substituting locally made goods for imported supplies. Input data came from two mines running both types of section under comparable geological conditions, covering worker numbers, skill profiles, cost structures and import dependence, then calibrated to industry totals to drive a socio-economic model.

Fine coal was screened at small apertures while surface moisture stayed below about 5 per cent. Above that, fines adhered to the coarser particles and screening became very difficult. The dual vibrating polyurethane mats stopped blinding and clogging, so screening area stayed available, but the screen action still could not dislodge fines from very damp coal.

Dolerite intrusion mechanisms and their metamorphic effect on coal were examined across four collieries in the south eastern Witbank Coalfield. In decreasing order of importance, intrusions cut safety by raising the risk of roof, pillar and floor failure, raise mining costs, reduce saleable tonnage, and increase waste generation and environmental risk.