Hydraulic mining
Hydraulic mining is a form of
Hydraulic mining developed from ancient Roman techniques that used water to excavate soft underground deposits. Its modern form, using pressurized water
blocking waterways and covering farm fields. These problems led to its legal regulation. Hydraulic mining has been used in various forms around the world.History
Ground Slucing
Hydraulic mining had its precursor in the practice of ground sluicing, a development of which is also known as "
Water was used on a large scale by Roman engineers in the first centuries BC and AD when the
Las Médulas is now a
]California Gold Rush
The modern form of hydraulic mining, using jets of water directed under very high pressure through hoses and nozzles at gold-bearing upland paleogravels, was first used by Edward Matteson near
Early placer miners in California discovered that the more gravel they could process, the more gold they were likely to find. Instead of working with pans, sluice boxes, long toms, and rockers, miners collaborated to find ways to process larger quantities of gravel more rapidly. Hydraulic mining became the largest-scale, and most devastating, form of placer mining. Water was redirected into an ever-narrowing channel, through a large canvas hose, and out through a giant iron nozzle, called a "monitor". The extremely high pressure stream was used to wash entire hillsides through enormous sluices.
By the early 1860s, while hydraulic mining was at its height, small-scale placer mining had largely exhausted the rich surface placers, and the mining industry turned to hard rock (called quartz mining in California) or hydraulic mining, which required larger organizations and much more capital. By the mid-1880s, it is estimated that 11 million ounces of gold (worth approximately US$7.5 billion at mid-2006 prices) had been recovered by hydraulic mining .
Environmental impacts
While generating millions of dollars in tax revenues for the state and supporting a large population of miners in the mountains, hydraulic mining had a devastating effect on
Cities and towns in the
Marysville eventually constructed a complex levee system to protect the city from floods and sediment. Hydraulic mining greatly exacerbated the problem of flooding in Marysville and shoaled the waters of the Feather River so severely that few steamboats could navigate from Sacramento to the Marysville docks. The sediment left by such efforts were reprocessed by mining dredges at the Yuba Goldfields, located near Marysville.
The spectacular eroded landscape left at the site of hydraulic mining can be viewed at Malakoff Diggins State Historic Park in Nevada County, California.[5]
The San Francisco Bay became an outlet for polluting byproducts during the Gold Rush. Hydraulic mining left a trail of toxic waste, called "slickens," that flowed from mine sites in the Sierras through the Sacramento River and into the San Francisco Bay.[6] The slickens would contain harmful metals such as mercury. During this period, the industrial mining industry released 1.5 billion yards of toxic slickens into the Sacramento River. As the slickens traveled through California's water arteries, it deposited its toxins into local ecosystems and waterways.[7]
Nearby farmland became contaminated, which led to political pushback against the use of hydraulic mining. The slickens flowed through the Sacramento River before depositing itself into the San Francisco Bay. Currently, the San Francisco Bay remains dangerously contaminated with mercury. Estimates suggest that it will be another century before the Bay naturally removes the mercury from its system.[8]
Legal action landmark case
Vast areas of farmland in the Sacramento Valley were deeply buried by the mining sediment. Frequently devastated by flood waters, farmers demanded an end to hydraulic mining. In the most renowned legal fight of farmers against miners, the farmers sued the hydraulic mining operations and the landmark case of
Hydraulic mining on a much smaller scale was recommenced after 1893 when the United States Congress passed the Camminetti Act which allowed such mining if sediment retention structures were constructed. This led to a number of operations above sediment catching brush dams and log crib dams. Most of the water-delivery hydraulic mining infrastructure had been destroyed by an 1891 flood, so this later stage of mining was carried on at a much smaller scale in California.
Beyond California
Although often associated with California due to its adoption and widespread use there, the technology was exported widely, to
Hydraulic mining was used during the
Hydraulic mining was used extensively in the Central Otago Gold Rush that took place in the 1860s in the South Island of New Zealand, where it was also known as sluicing.
Starting in the 1870s, hydraulic mining became a mainstay of alluvial tin mining on the Malay Peninsula.[11] Hydraulicking was formerly used in
Contemporary usage
In addition to its use in true mining, hydraulic mining can be used as an
Hydraulic mining is the principal way that kaolinite clay is mined in Cornwall and Devon, in South-West England.
Egypt used hydraulic mining methods to breach the Bar Lev Line sand wall at the Suez Canal, in Operation Badr (1973) which opened the Yom Kippur War.
Rand gold fields
On the South African Rand gold fields, a gold surface tailings re-treatment facility called East Rand Gold and Uranium Company (ERGO) has been in operation since 1977.[14] The facility uses hydraulic monitors to create slurry from older (and consequently richer) tailings sites and pumps it long distances to a concentration plant.
The facility processes nearly two million tons of tailings each month at a processing cost of below US$3.00/t (2013). Gold is recovered at a rate of only 0.20 g/t, but the low yield is compensated for by the extremely low cost of processing, with no risky or expensive mining or milling required for recovery.[15]
The resulting slimes are pumped further away from the built-up areas permitting the economic development of land close to commercially valuable areas and previously covered by the tailings. The historic yellow-coloured mine dumps around Johannesburg are now almost a rarity, seen only in older photographs.
Uranium and pyrite (for sulfuric acid production) are also available for recovery from the process stream as co-products under suitable economic conditions.
Underground hydraulic mining
High-pressure water jets have also been used in the underground mining of coal, to break up the coal seam and wash the resulting coal slurry toward a collection point.[1] The high-pressure water nozzle is referred to as the 'hydro monitor'.[16]
See also
- Hydrology
- Hydropower
- Hydraulic fracturing, use of high-pressure water in oil and gas drilling
- Pressure washer, similar use of high-pressure jets of water
- Water jet cutter, similar use of high-pressure jets of water
- Cigar Lake Mine, uses similar method of high pressure water to mine uranium
- Borehole mining, remote operated similar use of high-pressure jets of water.
References
- ^ a b Paul W. Thrush, A Dictionary of Mining, Mineral, and Related Terms, US Bureau of Mines, 1968, p.560.
- ^ Paul W. Thrush, A Dictionary of Mining, Mineral, and Related Terms, US Bureau of Mines, 1968, p.515.
- ^ Randall Rohe (1985) Hydraulic mining in the American West, Montana: The Magazine of Western History, v.35, n.2, p.18-29.
- ISBN 978-0-8090-9535-3.
- ^ "Malakoff Diggins SHP". State of California.
- ISBN 9780520933484.
- ^ "Mercury in San Francisco Bay". KQED. 5 November 2015. Retrieved 19 October 2022.
- ^ "Mercury in San Francisco Bay". KQED. 5 November 2015. Retrieved 19 October 2022.
- ^ Hydraulic mining outlawed [1] accessed 19 Jan 2014
- ^ "Oriental Claims Historic Area - Park Notes" (PDF). Parks Victoria Official Site. Parks Victoria. Archived from the original (PDF) on 3 March 2011. Retrieved 16 October 2010.
- ^ Mark Cleary and Kim Chuan Goh, Environment and Development in the Straits of Malacca, London: Routledge, 2000, p.47.accessed 5 November 2009.
- ^ George J. Young, Elements of Mining, 4th ed., New York: McGraw-Hill, 1946, p.436-438.
- ^ Anchor, Eric Johnson, KOMO News (17 May 2023). "Eric's Heroes: The work behind the 'Denny Hill Regrade' and how it changed Seattle". KOMO. Retrieved 27 June 2023.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "DRDGold Ergo fact sheet October 2012" (PDF). Retrieved 19 January 2013.
- ^ "Ergo: Mining South Africa's wealth again" (PDF). Retrieved 19 January 2013.
- ^ "Borehole Mining". Great Mining. Retrieved 23 November 2011.
- Hydraulic Mining in California: A Tarnished Legacy, by Powell Greenland, 2001
- Battling the Inland Sea: American Political Culture, Public Policy, and the Sacramento Valley: 1850-1986., U.Calif Press; 395pp.
- Gold vs. Grain: The Hydraulic Mining Controversy in California's Sacramento Valley, by Robert L. Kelley, 1959
- Lewis, P. R. and G. D. B. Jones, Roman gold-mining in north-west Spain, Journal of Roman Studies 60 (1970): 169-85