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mining was completed to a depth of 3,378 feet in 1961. Subsequently, 11 more tubbed shafts were sunk in the Saskatchewan potash basin along with two shafts with welded steel linings in the water-bearing sections. The use of the rockbolt for temporary support was another major step forward in shaft sinking that was initiated during this period. A number of different types of mechanical anchorages were developed for rockbolts in the 1940s. However, the time and expense in drilling holes for rockbolts negated their advantages. Up until 1945 the drilling of rock was still time-consuming in spite of almost a century of development work. In that year, a historic conversion from alloy steel to tungsten carbide-tipped Patrick Harrison drill steel took place in Sweden. Originating in Germany in the 1920s, the development of tungsten carbide bits culminated in Sweden in the early 1940s. Secoroc started production on a small scale in 1940, and the first cemented carbide bit was produced in 1943. During the 1950s and 1960s development continued for extension drill rods. In the 1960s, drill steel manufacturing in Sweden was restructured, giving rise to two companies — Secoroc and Sandvik. 1961 In 1948, the Alimak raise climber was introduced to the mining industry and in 1962, the first commercial raisebore machine was introduced. Using either one of these machines, if shaft bottom access was available,Uit wasNnow possible to raise and slash a shaft handling the broken muck on the shaft bottom. Using this method of shaft sinking, advance rates 72 could be increased if bottom access to the shaft was available. During this entire period, shaft sinking in Canada was dominated by one mining contractor — Patrick Harrison & Co. Ltd. The company was actually first established in 1934 in Val-d’Or, Quebec, and sank a number of shafts in that area. It was, however, the work carried out in the unstable ground conditions of the Quebec asbestos mines that established the company as a major force in North American shaft sinking. The majority of the shafts sunk in the Elliot Lake uranium boom were sunk by PH & Co. Seven frozen shafts were sunk in the Saskatchewan potash basin in a joint venture with a German consortium, and a huge contract was carried out to develop the Thompson nickel properties for Inco. At the time of the Thompson contract it was the largest underground development project ever let to a mining contractor. A total of 1,500 persons were employed. These are but a few of a total of 600 shafts sunk by PH & Co. in its relatively brief history. It was during this period, as well, that the technology for the drilling of mine shafts using rotary drilling techniques took some giant leaps forward. Between 1961 and 1969, there was huge progress made in the drilling of shafts using modified oil field rotary drilling equipment. The biggest 66 | CIM Magazine | Vol. 3, No. 2
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effort during this period was at the U.S. Nevada test site of the Atomic Energy Commission. Holes with diameters of 72 inches were drilled to depths of 4,200 feet. Some of these holes were completed in as little as seven months. Besides the drilling at the Nevada test site, a number of other shafts were completed. In 1966, a 60-inch diameter shaft was completed for the Bunker Hill Company at their Higden mine in Missouri. In the same year, Kermac Potash Company completed an 8.5 foot diameter shaft to a depth of 1,650 feet. One of the deepest shafts drilled during this period was in 1969 when a 6,150 foot (1,875 metres) deep shaft 90 inches (2.28 metres) in diameter was drilled in the Aleutian Islands of Alaska. Perhaps more important to shaft sinking were two shafts drilled in Holland at the Beatrix mine between 1955 and 1959. These shafts were 7.65 metres in diameter and just over 500 metres deep, drilled using the pilot hole and ream method whereby an initial pilot hole 2 metres que B in diameter is initially drilled and then enlarged in stages to its final diameter. The shafts were kept completely full of drilling mud at all times during drilling and a combination wall of steel and concrete was installed after the shaft drilling had been completed. The drilling of Beatrix II was started in August 1955 and completed in January 1959 — a total of 1,130 days, for an advance rate of approximately 0.45 metres per day. The installation of the lining required an additional 44 days. During this period, shaft sinking rates again increased 4 threefold from 30 to 40 metres per month to 90 to 110 metres per month. CIM
Bibliography Brown, E.O.F. (1927). Vertical Shaft Sinking. London: Ernest Benn Ltd.
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Dellinger, T. B. (1966). Current status of big hole drilling. The Annual Meeting of the American Institute of Mining, Metallurgical and Petroleum Engineers. New York: American Institute of Mining, Metallurgical and Petroleum Engineers. Hynd, J.G.S. (1960). Shaft sinking through water bearing dolomite. Canadian Mining Journal, August, 74–76. Jamieson, D.M., Pearse, M.P., & Plumstead, E.R.A. (1961). The evolution of shaft design and sinking technique in South Africa. Transactions of the Seventh Commonwealth Mining and Metallurgical Congress (Vol. 2, pp. 589-625). Johannesburg: South African Institute of Mining and Metallurgy. Jansen, F., & Glebe, E. (1960). Shaft sinking in the West German coal mining industry. Proceedings of the I.M.E. Symposium on Shaft Sinking and Tunneling. London: The Institution of Mining Engineers. Jaros, A. (1967). Shaft sinking methods in Czechoslovakia. In G.L. Colborne ( Ed.), Index ’67 — Saskatchewan Industrial Exposition and Mineral Symposium 1967 (pp. 121-127). McIntyre, J.T. (1949). Shafts of the New Consolidated Gold Fields Group. Symposium on Shafts and Shaft Sinking. Johannesburg: The Chemical Metallurgical and Mining Society of South Africa. Smit, G.L. (1964). Sinking and commissioning of the Eastern Twin Shaft System at Buffelsfontein Gold Mining Company Limited. Presented at the Annual Meeting of the American Institute of Mining, Metallurgical and Petroleum Engineers. New York: Society of Mining Engineers of AIME.