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 ?
Its projects of shaft sinking at Ukwa and Munsar mines and high-speed shafts at Balaghat and Gumgaon mines are progressing as per schedule.
Shaft sinking and construction at Turquoise Ridge is also on track, and along with a focus on improved efficiencies and cost discipline, it too has the potential for Tier One status.
In accordance with this, the Airth project has been re-phased and shaft sinking deferred for 12 months.' Scottish Miners' leaders planned to protest about the decision which they claimed had been made without consultation.
Nevada Copper has awarded the contract for shaft sinking and underground mine development work to Cementation USA Inc.
A SHAFT sinking machine has been officially unveiled as Sirius Minerals marks a major milestone in the construction of a PS3.5bn mine, set to create thousands of jobs.
The first 700 metres of the winze will be raisebored down to the 1,900-metre level and then slashed and extended beyond that to the 2,650-metre level using conventional shaft sinking technology.
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.
At the Hira- Buddini and Uti gold mine,the second phase of mining by shaft sinking and mine development is in process.
Shaft sinking crews can also expect shaft-floor cleaning to be carried out at a much faster rate, a development that has already been apparent in the pre-sink zone.
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.