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In gear generation, the tooth flanks are obtained as an outline of the subsequent positions of the cutter, which resembles in shape the mating gear in the gear pair. There are two machining processes employed shaping and milling. There are several modifications of these processes for different cutting tool used. [4]
A drum hoist (steel wire rope visible) and motor. In underground mining a hoist or winder [1] is used to raise and lower conveyances within the mine shaft.Modern hoists are normally powered using electric motors, historically with direct current drives utilizing Ward Leonard control machines and later solid-state converters (), although modern large hoists use alternating current drives that ...
Soapstone undergoes transformations when heated to temperatures of 1,000–1,200 °C (1,830–2,190 °F) into enstatite and cristobalite; on the Mohs scale, this corresponds to an increase in hardness to 5.5–6.5. [5] The resulting material, harder than glass, is sometimes called "lava". [6]
Shaft mining or shaft sinking is the action of excavating a mine shaft from the top down, where there is initially no access to the bottom. [1] Shallow shafts , typically sunk for civil engineering projects, differ greatly in execution method from deep shafts, typically sunk for mining projects.
In Yellowknife, Canada, the demolition of the Con Mine headframe has met significant public opposition. [5] The headframe was the tallest structure in the Northwest Territories [ 6 ] and is regarded by many in the town to be an important symbol of the region's mining heritage.
Room and pillar mining was one of the earliest methods used, [3] although with significantly more manpower. The room and pillar system is used in mining coal , gypsum , [ 4 ] iron , [ 5 ] limestone , [ 6 ] and uranium [ 7 ] ores, particularly when found as manto or blanket deposits, stone and aggregates , talc , soda ash , and potash . [ 8 ]
19th-century miner pouring water into a rocker box which, when rocked back and forth, will help separate gold dust from the alluvium. Placer mining (/ ˈ p l æ s ər /) [1] is the mining of stream bed deposits for minerals. [2] This may be done by open-pit mining or by various surface excavating equipment or tunneling equipment.
The Mountain Pass Rare Earth Mine and Processing Facility, owned by MP Materials, is an open-pit mine of rare-earth elements on the south flank of the Clark Mountain Range in California, 53 miles (85 km) southwest of Las Vegas, Nevada. In 2020 the mine supplied 15.8% of the world's rare-earth production.