Consolidation of mine fill by freezing

CIM Bulletin, Vol. 78, No. 877, 1985

MICHAEL L JEREMIC Professor of Rock Mechanics and Mining Engineering, Laurentian University, RACHELS. PRUDHOMME, Mining Engineer, M.Sc. Student, Laurentian University

The consolidation of mine backfill by freezing is a concept which has been under study in the mining engineering laboratories at Laurentian University during the past three years. The proposed underground application of freezing involves the artificial freezing of in-situ backfill by means of a refrigerated brine solution which would be circulated through a circuit of freeze pipes. The most interesting findings to date are: (1) The uniaxial compressive strength of frozen fill is considerably higher than that of cemented fill in a ratio of 20:1 (aggregate to cement), and (2) load deformation characteristics of the frozen fill suggest that a higher ice content results in more brittle failure and that samples which have initially failed can still support up to one-half the ultimate load without additional failure. Although at this early stage a detailed economic analysis of the procedure has not been possible, a general evaluation of the costs involved suggests that the method could be competitive with the hydraulic placement of cemented backfill. Results obtained from laboratory investigations indicate that the freezing of backfill is a structurally feasible option.
Keywords: Mining methods, Backfill, Freezing, Mill tailings, Slopes, Shaft sinking, Compressive strength, Brine.