Backfill practice and technology at Kidd Creek Mines
Kidd Creek Mines primarily employs sublevel blasthole sloping for underground mining operations. During pillar recovery in No. 1 Mine and panel mining in No. 2 Mine, the free standing fill exposures may reach a height of 100 m or more. Consequently, a competent consolidated rockfill has been required to fill the mined openings.
Since 1976, a total of more than fifty slopes and pillars have been filled with over four million tonnes of backfill. Fill exposures, up to heights of 100 m, have stood up well after blasting adjacent to the backfill.
The fill material consists of a graded aggregate, Portland cement and ground slag. Sand has been occasionally mixed in the fill material to serve as a void filler. The aggregate is prepared in a fill crushing plant, transported underground through raises, and hauled to the filling slopes by conveyors in No. 1 Mine and by trucks in No. 2 Mine.
Two mixing methods are currently in use. No. 1 Mine utilizes the free fall of gravity; the fill materials are sprayed with cement slurry as the aggregate departs from the conveyor into a mixing culvert. The other is the use of a rotary mixer on a batch basis in No. 2 Mine.
This paper describes the fill systems, filling operations, and the backfill quality control practice, together with various testing results related to improving fill quality as well as reducing fill costs.
Rock mechanics, Backfill practice, Kidd Creek Mines Ltd., Blasting, Blasthole sloping, Underground mining, Aggregates, Portland cement, Ground slag.