Mining technology in 1974 / R. J. R. Welwood. : M38-13/76-29E-PDF

"The tonnage of metallic ore mined underground in Canada decreased slightly to 64.4 million tons in 1974 from 65.5 million tons in 1973, a decrease of 1.7%. An increase of less than 1% in surface-mined ore brought the total from surface operations to 239.7 million tons, i.e. approximately 79% of the total metallic ore mined in Canada. In the non-metallic mines, there was a 10.6% increase from underground, largely owing to increased production of potash. A minor increase occurred in surface-mined non-metallic ores. During 1974, approximately 40% of the metallic underground ore was mined by cut and fill methods or variations, followed by open stoping with about 36%. The tons mined by other underground methods were slightly reduced. Sharp rises in underground mining costs are noted for 1974. This trend is expected to continue at a high rate in 1975. Surface mining costs in general showed only slight increases"--Summary, p. i.

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