00000nam 2200000za 4500 9.841727 CaOODSP 20221107152146 cr ||||||||||| 170816s1974 oncd os f000 0 eng d CaOODSP eng eng fre n-cn--- M34-20/188E-PDF M34-20/188 Dubnie, Amil. Mining technology - statistics 1972 and 1973 developments [electronic resource] / Amil Dubnie, Mining Research Centre. Ottawa : Information Canada, 1974. iv, 29, [2] p. : chart Technical bulletin ; TB 188 Cover title. "May, 1974." Digitized edition from print [produced by Natural Resources Canada]. “The tonnage of metallic ore mined underground in Canada decreased in 1972 while a corresponding increase took place in the tonnage mined from surface bringing the latter to 72% of the total. In the non-metallic less coal mine category, tonnages showed only a minor increase. In coal mines, the tonnage derived from surface increased, reaching 79% of the total for the group. During 1972, about 37% of underground metallic ore was mined by the cut-and-fill method or variations, followed by open stoping at 31%. The general trend of underground mining costs is up, while productivity has not shown a comparable rise. Costs and productivity in surface mines are holding approximately at previous levels. Promising advances in underground mining during 1973 were the use of a "roadheader" for mining without drilling and blasting under certain conditions, and the application of large-diameter holes to open stoping"--Summary, p. i. Includes summary in French. gccst Mining industry gccst Statistics Canada. Natural Resources Canada. Canada. Mines Branch. Technical bulletin (Canada. Dept. of Energy, Mines and Resources. Mines Branch) TB 188 (CaOODSP)9.834857 PDF 1.52 MB https://publications.gc.ca/collections/collection_2017/rncan-nrcan/M34-20/M34-20-188-eng.pdf 300067