shaft sinking

shaft sinking,

excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnelstunnel,
underground passage usually made without removing the overlying rock or soil. Although tunnels are approximately horizontal, they must be built with sufficient gradient for proper drainage.
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, which are horizontal. Little difficulty is experienced in shaft sinking through solid rock, which contains little water. When loose, water-bearing strata have to be contended with, careful shoring and sealing of the shaft lining become necessary, and pumping facilities are needed. Shafts are usually circular or rectangular and are generally lined with wood, masonry, concrete, steel, or cast iron. Shafts sunk in loose water-bearing soils, where there is great external pressure on the shaft sides, are nearly always circular; rectangular shafts with wood lining are often used in mining work, as the shafts are frequently of a temporary nature. Shaft sinking through rock is generally accomplished by blasting. When the loose surface material has been removed, holes are drilled, and the charges are placed and are fired by electricity. The broken rock is removed and the process is repeated. In an ordinary rectangular shaft the lining consists of timbers 8 or 12 in. (20 or 30 cm) square placed horizontally around the shaft. Shafts of a more permanent nature are generally circular in form and lined with cast iron or with concrete masonry 1 to 2 ft (30–61 cm) thick, built in sections as the work advances. When excessive quantities of water are met with, cast-iron tubbing is sometimes used. This consists of heavy cast-iron rings made in segments, with flanges for connecting, and bolted together in place. Cement grout is forced into the space between the outside of the tubbing and the surrounding earth to form a seal. Shaft sinking by the freezing process in very watery soil is accomplished by sinking pipes in the area to be excavated and circulating brine at low temperature in them until the earth is frozen and hard so that it can be excavated in the same manner as rock. In the grouting method, liquid cement is forced into the water-bearing earth under very high pressure. On mixing with the water, the cement solidifies the adjacent area, and it is removed by drilling and blasting as with rock.

shaft sinking

[′shaft ‚siŋk·iŋ]
(mining engineering)
Excavating a shaft downward, usually from the surface, to the workable coal or ore.
References in periodicals archive ?
3bn Whitby mine and Teesside processing plant has signed a shaft sinking contract with a new company - DMC Mining Services.
The Central Shaft project continues to progress well with pleasing progress in shaft sinking during the Quarter.
The C20 Rock Splitter quickly breaks large boulders and solid rock in mining and shaft sinking applications as well as cross passage work in tunneling.
Having reverted back to deputy in 1977, Tony then worked on the shaft sinking at Wistow Mine in the Selby Complex where he became Colliery overman in 1983 - a position he held until illhealth retirement in 1995.
These include road construction, demolition works, secondary breaking, foundation drilling, trenching, shaft sinking as well as dimensional stone quarrying.
Shaft sinking will get underway in June 2016 if KGHM opts for two shafts, or in September 2016 if it decides on the single shaft option.
At the Hira- Buddini and Uti gold mine,the second phase of mining by shaft sinking and mine development is in process.
Deilmann-Haniel multipurpose excavators are being used for shaft sinking and mine infrastructure operations.
The transaction includes the company's hard rock drilling, loaders, dump trucks, shaft sinking and raise bore product lines, which generated 2013 sales of some USD90m (EUR65m), according to a statement by the buyer.
The industry is growing at an annual 20 percent and has a global competitive advantage in four areas aACAo mine safety, ventilation, shaft sinking, and tracked mining,aACA[yen] said the report.
Shaft sinking operation may consume up to 60% of time of the underground mine development stage (Unrug 1992).