LETTER TO THE EDITOR — RTF method unique to Geco

I read, with special interest, the Odds ‘n’ Sods article by Mr. S.J. Hunter referring to the Geco mining system (T.N.M., May 15/95). Mr. Hunter’s frequent contributions and references to unique individuals and events in mining’s history continue to draw attention to the many significant accomplishments in our industry. Many of these accomplishments continue to serve as well today.

One of these is the “Geco Method,” otherwise known as “Running Tight Fill (RTF),” which was referred to by Mr. Hunter. This innovative practice was conceived, out of necessity, at the underground Geco division mine in northwestern Ontario, which is owned and operated by Noranda Minerals. RTF was first introduced in our B zone in the 10-22 block in 1959, almost five years after mining began at Geco. The original mine plan had incorporated 50-ft. open stopes and 50-ft. pillars. But a variety of factors — poor rock competency in some areas, jointing, faulting and weak contacts along diabase dykes — caused the stope wall and pillars to fail quickly. Results were generally poor, with dilution often exceeding 30%.

Experiments between 1959 and 1961 involved introducing coarse quarry material through fill raises from surface. Combinations of hydraulic fill and cemented fill were used. A backfill plant was started up in 1965, subsequent to which dilution has averaged 10%.

Geco was established in 1955, when reserves totalled less than 15 million tonnes. But when it closes at the end of 1995, it will have processed 54 million tonnes grading 1.85% copper and 3.76% zinc, as well as 1.63 oz. silver per ton.

I believe Geco’s minable reserves would have been substantially lower, and the mine’s potential not fully realized, had it not been for an innovative method developed in response to our ground conditions. Those directly involved in this achievement were Lorne Brooks, Peter McLeod and Art Schwartz. Guiding this important effort was Geco’s first mine manager, Jack Graham.

Maurice Ethier, Mine Manager

Geco Divison, Manitouwadge, Ont.