Historically, the majority of gold was mined from placer deposits, where gold has settled out of an existing or ancient waterway downstream of where nuggets had eroded out of rock outcrops. nbspSome early miners also used an early form of hardrock mining, digging solid veins of gold out of rock, where mineralized water had deposited it over thousands of years. nbsp
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Today, gold is extracted in hardrock mines that directly mine the source rock, or lode of gold, where it was originally deposited by geochemical processes. nbspMost ore accessed this way today contains only microscopic grains of gold, and it takes tons of rock to produce ounces of gold. nbspHardrock mines can be either underground mines or strip mines, and are usually more environmentally destructive than placer mining.
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The stereotypical grizzled gold-rush prospector panning for gold was searching for placer gold, or gold deposited in a waterway.nbsp Placer mining takes a variety of forms, including panning, sluice-boxing, hydraulic mining, and dredging.nbsp All of these techniques use gravity and water to separate the dense gold from the lighter sand and gravel.nbsp Some modern commercial placer operations are quite large and utilize heavy equipment and river diversions.
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Placer mining targets native gold that isnt chemically bound up within the rock itself.nbsp The sources of all placer gold are lodes, or veins of gold naturally formed within the rock. Ongoing weathering and erosion of rock outcrops continuously exposes new fragments of gold that wash downstream. Because gold is far denser than most rock 19.3 gcc as opposed to about 2.7 gcc it settles into little pockets between large rocks or into bedrock fissures.nbsp Gold accumulates in such places while othe
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Mine pit at Fort Knox hardrock gold mine GET PHOTO Fort Knox hardrock gold mine pit sourcenbspCopyright held by photographer
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The vast majority of current gold production comes from commercial hardrock mining operations.nbsp In these mines, the gold is extracted from the rock where it was originally deposited.nbsp
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Some hardrock mines are underground mines. A tunnel is drilled or blasted to the source of the ore, which is transported out for processing often by truck or rail.nbsp A variety of specific techniques can be used for mining the ore, depending on the geology of the area - such as block caving, which allows massive strip-mine scale underground excavation, or the more steretypical cut-and-fill and drift-and-fill techniques, where miners dig our out in long horizontal tunnels.
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Other hardrock mines are large strip mines that remove the surface dirt and rock and then extract the ore from the resulting open pit.nbsp Removal of ore is often accomplished explosives, enormous power shovels, and massive trucks, some capable of carrying 500 tons of rock in one load.
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In both kinds of hardrock mining, the ore is then processed in some manner to remove the gold.nbsp Usually this entails crushing the rock into powder and using some combination of gravity, centrifugation, and froth flotation to perform an initial separation of gold from rock.nbspnbsp In many cases this is followed by some form of cyanide treatment to precipitate out the remaining gold.nbsp The remaining ore mud waste is known as tailings, the disposal of which is one of the largest challenges fa
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The cradle, long-tom and puddling-tub are now little used in districts where work has been carried on for a long time except by the Chinese, who gain a precarious livelihood with their help by washing over the heaps of tailings accumulated from sluicing or hydraulic mining operations in Australia and California.
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In new districts, however, for a short time after shallow deposits have been discovered, they are still extensively used. On the Klondike and at Cape Home, for example, thousands of diggers used them, latter day improvements on the old cradle being especially numerous.
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In Siberia, in the Urals and in the valleys of the Obi, the Yenisei and the Lena, individual workers still exclusively use a trough, which differs from the long-tom mainly in requiring more constant attention on the part of the operator, and which resembles the old German buddle. The trough consists of a rectangular box open above and at one end.
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Gold CIP Production Line. Process Introduction. CIP Carbon in pulp process is a high efficient method to leaching and recovering gold from gold ore, The most different from CIL process is in CIP process, gold leaching and adsorption are separated, first leaching, and then adsorption. Now it is being replacing by CIL process progressively.
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Dec 18, 2016nbsp018332Silver Mining Process . Silver is mined using a number of processes. One of the most common processes of extracting silver metal for the ore is the heap leach or cyanide process. The process is most popular with many miners because it is low
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Jul 13, 2016nbsp018332Actual mining could conceivably be conducted in this way, trip by trip, but the process would be slow, and ROVs can bring up only so much weight. A faster way would be to bring in a
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Dec 29, 2014nbsp018332Top 36 mining interview questions with answers pdf 1. Free ebook Top 36 mining interview questions with answers 1 2. 2 Updated Top 10 mining interview questions with answers To Top 36 mining interview questions with answers On Mar 2017
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