Experimental investigation of the oxidation and consolidation of sulphide aggregates and the application to underground muck-piles—Lockerby Mine, Sudbury, Ontario
A bulk mining method is employed at the Lockerby mine resulting in the formation of large muck-piles. If these muck-piles remain in the slopes for some time they may agglomerate to the extent that the muck cannot be removed by a scoop-tram. A laboratory investigation was undertaken with sulphide material from the mine in order to detemine the time that oxidation begins and the flowability of the material as a function of several factors. The laboratory results are applied to the conditions in the muck-piles.
The time of the beginning of oxidation of the material decreases as the sulphide composition, water content and availability of air increases. Oxidation is retarded by the addition of a copper sulphate solution instead of water. The un-confined yield force (strength) of the material increases with an increase in the sulphide composition, water content and time. The material ceases to be free-flowing before there is visible evidence of oxidation and this suggests that oxidation actually begins earlier and that agglomeration is also due to the capillary action of water.
Broken ore should be removed from the slope prior to the time a muck-pile ceases to be free-flowing—perhaps as early as two days for high-grade ore and 5 days for low-grade ore. In order to control dust, 1.4 weight per cent of a 5 per cent solution of copper sulphate should be added to the muck-pile rather than water. This inhibits oxidation and increases the time that a muck-pile remains free-flowing.
Underground mining, Lockerby Mine, Blasthole slopes, Muck-piles, Sulphide ore, Oxidation, Agglomeration, Copper sulphate, Shear tests, Flow functions, Scooptrams, Breakout force