Applying tracer gas techniques to evaluate the air distribution in flood leaching stopes

CIM Bulletin, Vol. 81, No. 913, 1988

S. HARDCASTLE, CAN MET-EM R Elliot Lake, Ontario and A. SHEIKH Denison Mines Ltd. Elliot Lake, Ontario

Various methods of leaching are being used by Denison Mines Ltd. Uranium Operations. This study was designed to investigate the flood leaching operation of two parallel inter-connected stopes contained by pressure bulkheads. The leaching muck piles, created from large scale uppers production blasts, are aerated by compressed air lines laid beneath the pile prior to blasting. A SF6 tracer gas, injection technique has been employed to determine the post-blast integrity of the single-ended air distribution system. SF6 was injected into the compressed air line feed to the stopes and collected at borehole exhausts from the stopes in grab-sampling bags. Analyses of the air samples were performed with a gas chromatograph. The system was designed to give a sufficiency of oxygen to sustain bacterial activities used to enhance the leaching recovery in the muck piles. The results obtained indicated that there is a minor anomaly in the distribution system that may not be critical to the operation. Compared to an idealized case, the over-all efficiency of aeration throughout the muck is estimated at over 85%.
Keywords: Ventilation, Tracer gas, Leaching, Mining technology, Underground mining.