Sirgala karjäärist veavad 200 tonnised karjäärikallurid tuhandeid tonne raumaaki Kukruse teele, mööda üldkasuatatavaid teid. Sellega seoses on pealelaadimiseks hangitud Eesti suurim 20m3 pöördkoppekskavaator, ning rajatud 100 m sügavune karjäär. Kõike need rekordid on püstitatud vaid selleks, et tasuta liiva müüa. Seda jutustab artiklile lisatud pilt.

Abiks:

http://belaz.minsk.by/production/
http://www.hitachi-c-m.com/global/products/excavator/large/ex3600-6/index.html

 Viidatud lugu:

Kadri Bank, aripaev.ee 20. juuli 2009 05:31

ITAR-TASS     Seaduseaugu tõttu annab riik Eesti Energia käe läbi võileivahinnaga ära ehitusmaterjali Kukruse-Jõhvi teelõigule, jättes aga ennast ilma paarikümnest miljonist kroonist. Juba enam kui kuu sõidavad Ida-Virumaal asuva Sirgala karjääri ja tänavuse kalleima teedeehituse vahet kallurid, kastis tuhanded tonnid liiva. Eesti Energia Kaevandustele kuuluvast karjäärist ostab teedeehituskonsortsium seda materjali hinnaga, mis ei küüni väidetavalt üle paarikümne sendi tonni kohta, kirjutab Äripäev.     Tehingu osapooled — Eesti Energia Kaevandused ja ehitajad eesotsas Talteriga — hinda avalikustama ei soostu, öeldes, et lepingus fikseeritud hinnad sisaldavad konfidentsiaalset infot. Eesti Energia Kaevanduste arendusdirektor Kalmer Sokman lisab, et ehitajale müüakse ühe lepingu raames nii killustikku, aherainet kui ka liiva ja eraldi iga materjali hinna väljatoomine jätaks eksitava mulje.

Vaata lisaks:

aripaev.ee: Kingitud miljonid

New lab designed to study dark matter is now under construction

Construction crews have now started building the deepest underground science laboratory in the world, which scientists will use to study dark matter.

“The fact that we’re going to be in the Davis Cavern just tickles us pink,” Case Western Reserve University researcher Tom Shutt told the Associated Press. The cavern used to be a gold mine that has been abandoned for some time now. The part of the mine called Davis Cavern is named after Ray Davis Jr., a scientists who used the mine to study solar neutrinos in the 1960s.

The research lab, located at a depth equivalent to six Empire State buildings, will be used to help scientists study dark matter. Being almost 5,000 feet under the Earth’s surface is an ideal location as cosmic rays likely won’t interfere with research, but it will be some time before researchers are able to begin working there.

Engineers and construction crews must now stabilize and repair some of the tunnels, and add new safety infrastructure to prevent tunnel collapse. Research already is being conducted at 4,850 feet, with Congress mulling two labs that would go even deeper than the one now being built.

Case Western Reserve University, Brown University, and a couple of other universities and research groups are helping develop the new underground science laboratory. Around a dozen total collaborators plan to research dark matter at the facility.

The Large Underground Xenon (LUX) detector equipment — a project aimed at studying the Big Bang explosion — is expected to be the first dark matter experiment.

Dark matter is a popular topic of research because many astronomers believe galaxies may have never formed without dark matter. Furthermore, the theory behind dark matter and what it is remains a mystery — learning more about dark matter may help physicists finally figure out if the universe is expanding or contracting.

The lab should be fully operational by 2016. http://www.dailytech.com/article.aspx?newsid=15510

Were is the deepest mine in the world?

In: Geology, Engineering [Edit categories]

South Africa is where it’s at for deep mines. And what are they digging for? Gold! AngloGold Ashanti’s Savuka mine near Carletonville is currently the world’s deepest mine at just less than 3.8km below the surface.

Gold Fields mines Driefontein will be the world’s deepest mine at 4.1km below the surface and Kloof will be the second deepest mine at 4km underground when their extensions are complete. They’re digging them now.

At this stage AngloGold Mponeng mine is official the deepest mine in the world and the current project will take it another 300 meters deeper.

3.8Km underground – My experience in the deepest mine in the world

POSTED ON 05 DECEMBER 2008

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The world’s deepest pub

Lucille Davie

26 August 2002

Take your next tipple almost a quarter of a kilometre underground in what used to be a donkey stable in one of the world’s richest and deepest gold mines. That is, of course, if you don’t mind damp, dark places and don’t suffer from claustrophobia.

You can book this pub any day of the week from 5pm to 9pm, and get there by taking a large, clangy lift down 226 metres to spend a few hours where, back in the 1920s, some 300 donkeys stayed for three months while pulling cocopans filled with gold-laden rocks for removal above ground.

The pub is on level 5 of the mine known as Shaft 14 on what used to be Langlaagte, the farm on which the main reef was first discovered in Johannesburg in 1886, some six kilometres south of the city centre. The mine goes down 57 levels or 3 500 metres, and over its 90-year lifespan produced some 1.4 million kilograms of gold, blasted out of the ground by 30 000 miners.

The mine is part of the 100-kilometre reef stretching from Boksburg in the east to Randfontein in the west, and visible from a distance with its impressive head gear protruding above the surrounding mine dumps.

The pub – or the wooden doors of the old stable – is visible in the underground mine tour of Shaft 14 at Gold Reef City, the historical village, casino and pleasureland. The tour takes 35 minutes and will give you a glimpse of what it must have been like to work 12-hour shifts down the mine.

When Shaft 14 was opened in 1897, just 11 years after Johannesburg was established, there was no electricity at the mine. Lighting underground was by means of candles, which posed a risk for explosions caused by methane gas. Combined with the darkness, the wetness, the heat, the closeness and the ear-shattering noise of the drills, it was a tough way to earn a living.

Get ready to block your ears! (Picture: Lucille Davie)

The underground temperatures range from 30 degrees to 50 degrees, but with cooling systems temperatures can be maintained at around 28 degrees. With each drop of 100 metres underground, the temperature increases by one degree.

If you were wondering why the donkeys only stayed below ground for three months, it was because after that time they had invariably gone blind.

As you step out the lift underground, you look ahead to a whitewashed tunnel – to help returning miners adjust from the darkness to the brightness outside – and spend the tour walking down two-metre high tunnels, with the cocopan track down the middle of the tunnel.

Source: City of Johannesburg web site

From Wikipedia, the free encyclopedia

Coordinates: 69°23′46.39″N 30°36′31.20″E

Kola Superdeep Borehole, 2007

The Kola Superdeep Borehole (Russian: Кольская сверхглубокая скважина) is the result of a scientific drilling project of the formerUSSR. The project attempted to drill as deep as possible into the Earth’s crust. Drilling began on 24 May 1970 on the Kola Peninsula, using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A number of boreholes were drilled by branching from a central hole. The deepest, SG-3, reached 12,261 metres (40,230 ft) in 1989, and remains the deepest hole ever drilled.^[1] The longest hole ever drilled is the 12,290 m (40,300 ft) Maersk Oil BD-04A well at Al-Shaheen field in Qatar.^[2]

Contents [hide] 1 Digging 2 Research 3 Current Status 4 Other projects 5 See also 6 References 6.1 Bibliography 6.2 Notes 7 External links

[edit]Digging

The initial target depth was set at 15,000 m (49,000 ft). On 6 June 1979, the world depth record held by the Bertha Rogers hole in Washita County, Oklahoma at 9,583 m (31,440 ft)^[3] was broken. In 1983, the drill passed 12,000 m (39,000 ft), and drilling was stopped for about a year to celebrate the event.^[4] This idle period may have contributed to a break-down on 27 September 1984: after drilling to 12,066 m (39,590 ft), a 5,000 m (16,000 ft) section of drillpipe twisted off and was left in the hole. Drilling was later restarted from 7,000 m (23,000 ft).^[4] The hole reached 12,262 m (40,230 ft) in 1989. In that year the hole depth was expected to reach 13,500 m (44,000 ft) by the end of 1990 and 15,000 m (49,000 ft) by 1993.^[5] However, due to higher than expected temperatures at this depth and location, 180 °C (356 °F) instead of expected 100 °C (212 °F), drilling deeper was deemed unfeasible and the drilling was stopped in 1992.^[4] With the expected further increase in temperature with increasing depth, drilling to 15,000 m (49,000 ft) would have meant working at a projected 300 °C (570 °F), at which the drill bit would no longer work.

[edit]Research

The Kola borehole penetrated about a third through the Baltic continental crust, presumed to be around 35 kilometres (22 mi), exposing rocks 2.7 billion years old at the bottom.^{[citation needed]} The project has been a site of extensive geophysical studies. The stated areas of study were the deep structure of the Baltic Shield; seismic discontinuities and the thermal regime in the Earth’s crust; the physical and chemical composition of the deep crust and the transition from upper to lower crust; lithospheric geophysics; and to create and develop technologies for deep geophysical study.

To scientists, one of the more fascinating findings to emerge from this well is that the change in seismic velocities was not found at a boundary marking Jeffreys’ hypothetical transition fromgranite to basalt; it was at the bottom of a layer of metamorphic rock that extended from about 5 to 10 kilometers beneath the surface. The rock there had been thoroughly fractured and was saturated with water, which was surprising. This water, unlike surface water, must have come from deep-crust minerals and had been unable to reach the surface because of a layer ofimpermeable rock.^[6]

Another unexpected discovery was the large quantity of hydrogen gas, with the mud flowing out of the hole described as “boiling” with hydrogen.^[7]

[edit]Current Status

Kola Superdeep Borehole, commemorated on the 1987 USSRstamp

The site is currently controlled by the State Scientific Enterprise on Superdeep Drilling and Complex Investigations in the Earth’s Interior (GNPP Nedra) as the Deep Geolaboratory. As of 2003, the deepest active bore, SG-5, is 8,578 m (28,140 ft) and with a 214 mm (8.4 in) diameter.^{[citation needed]}

[edit]Other projects

The United States embarked on a similar project in 1957, dubbed Project Mohole, which was intended to penetrate the shallow crust under the Pacific Ocean off Mexico. However, after some initial drilling, the project was abandoned in 1966 due to lack of funding. This “failure” inspired great successes of the Deep Sea Drilling Project, Ocean Drilling Program, and the present Integrated Ocean Drilling Program.

[edit]See also

• Mohorovičić discontinuity
• Project Mohole
• Chikyu Hakken, deep oceanic drilling program
• Integrated Ocean Drilling Program
• San Andreas Fault Observatory at Depth
• Earthscope
• USARRAY
• Well to Hell hoax

[edit]References

[edit]Bibliography

• Fuchs, K., Kozlovsky, E.A., Krivtsov, A.I., and Zoback, M.D. (Eds.) (1990) Super-Deep Continental Drilling and Deep Geophysical Sounding. Springer Verlag, Berlin, 436 pp.
• Kozlovsky, Ye.A. (Ed.) (1987) The Superdeep Well of the Kola Peninsula. Springer Verlag, Berlin, 558 pp.

[edit]Notes

[edit]External links

• Official Kola Superdeep Borehole website (in Russian)
• The World’s Deepest Hole – Alaska Science Forum – July 1985
• Cassino, Adam (2003). “Depth of the Deepest Drilling“. The Physics Factbook.
• The Deepest Hole June 20, 2006

From Wikipedia, the free encyclopedia

Chuquicamata, Chile, site of the largest circumference and second deepest open pit copper mine in the world.

Break time underground,Colorado, ca. 1900

Mining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or (coal) seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash. Any material that cannot be grown through agricultural processes, or created artificially in a laboratory or factory, is usually mined. Mining in a wider sense comprises extraction of any non-renewable resource (e.g., petroleum, natural gas, or even water).

Mining of stone and metal has been done since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials and finally reclamation of the land to prepare it for other uses once the mine is closed. The nature of mining processes creates a potential negative impact on the environment both during the mining operations and for years after the mine is closed. This impact has led to most of the world’s nations adopting regulations to moderate the negative effects of mining operations. Safety has long been a concern as well, though modern practices have improved safety in mines significantly. Mining today is able to profitably and safely recover minerals with little negative impact to the environment.

[edit]History

[edit]Prehistoric mining

Chalcolithic copper mine in Timna Valley, Negev Desert, Israel.

Since the beginning of civilization people have used stone, ceramics and, later, metals found on or close to the Earth’s surface. These were used to manufacture early tools and weapons, for example, high quality flint found in northern France and southern England were used to create flint tools.^[1]Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Gravesare especially famous, and like most other flint mines, are Neolithic in origin (ca 4000 BC-ca 3000 BC). Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District.

The oldest known mine on archaeological record is the “Lion Cave” in Swaziland. At this site, which by radiocarbon dating proves the mine to be about 43,000 years old, paleolithic humans mined mineral hematite, which contained iron and was ground to produce the red pigment ochre.^[2][3] Mines of a similar age in Hungary and are believed to be sites where Neanderthals may have mined flint for weapons and tools.

[edit]Ancient Egypt

Ancient Egyptians mined malachite at Maadi.^[4] At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Later, between 2,613 and 2,494 BC, large building projects required expeditions abroad to the area of Wadi Maghara in order “to secure minerals and other resources not available in Egypt itself.”^[5] Quarries for turqoise and copperwere also found at “Wadi Hamamat, Tura, Aswan and various other Nubian sites”^[5] on the Sinai Peninsula and at Timna. Mining in Egypt occurred in the earliest dynasties, and the gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt, and are described by the Greek author Diodorus Siculus. He mentions that fire-setting was one method used to break down the hard rock holding the gold. One of the complexes is shown in one of earliest known maps. They crushed the ore and ground it to a fine powder before washing the powder for the gold dust.

[edit]Ancient Greece and Rome

Agricola, author of De Re Metallica

Drainage wheel from Rio Tinto mines

Mining in Europe has a very long pedigree, examples including the silver mines of Laurium, which helped support the Greek city state of Athens. However, it is the Romans who developed large scale mining methods, especially the use of large volumes of water brought to the minehead by numerous aqueducts. The water was used for a variety of purposes, including using it to remove overburden and rock debris, called hydraulic mining, as well as washingcomminuted or crushed ores, and driving simple machinery. They used hydraulic mining methods on a large scale to prospect for the veins of ore, especially a now obsolete form of mining known as hushing. It involved building numerous aqueducts to supply water to the minehead where it was stored in large reservoirs and tanks. When a full tank was opened, the wave of water sluiced away the overburden to expose the bedrock underneath and any gold veins. The rock was then attacked by fire-setting to heat the rock, which would be quenched with a stream of water. The thermal shock cracked the rock, enabling it to be removed, aided by further streams of water from the overhead tanks. They used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines. The methods had been developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being atLas Medulas, where seven long aqueducts were built to tap local rivers and to sluice the deposits. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited. They used reverse overshot water-wheels for dewatering their deep mines such as those at Rio Tinto. In Great Britain the natives had minedminerals for millennia ,^[6] but when the Romans came, the scale of the operations changed dramatically. The Romans needed what Britain possessed, especially gold, silver, tin and lead. Roman techniques were not limited to surface mining. They followed the ore veins underground once opencast mining was no longer feasible. At Dolaucothi they stoped out the veins, and drove adits through barren rock to drain the stopes. The same adits were also used to ventilate the workings, especially important when fire-setting was used. At other parts of the site, they penetrated the water table and dewatered the mines using several kinds of machine, especiallyreverse overshot water-wheels. These were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, and lifting water about 80 feet (24 m). They were worked as treadmills with miners standing on the top slats. Many examples of such devices have been found in old Roman mines and some examples are now preserved in the British Museum and the National Museum of Wales.^[7]

[edit]Medieval Europe

Mining in the Medieval period is best known through the work De Re Metallica (1556) of Georg Agricola, who described many different mining methods then used in German and Saxon mines. Use of water power in the form of water mills was extensive; they were employed in crushing ore, raising ore from shafts and ventilating galleries by powering giant bellows. Black powder was first used in mining in Selmecbánya, Kingdom of Hungary (present-day Banská Štiavnica,Slovakia) in 1627.^[8] This allowed blasting of rock and earth to loosen and reveal ore veins, which was much faster than fire setting. In 1762, the world’s first mining academy was established in the same town.

[edit]North and South America

Miners at the Tamarack Mine in Copper Country, Michigan, U.S. in 1905.

In North America there are ancient, prehistoric copper mines along Lake Superior.^[9][10] “Indians availed themselves of this copper starting at least 5000 years ago,”^[9] and copper tools, arrowheads, and other artifacts that were part of an extensive native trade network have been discovered. In addition, obsidian, flint, and other minerals were mined, worked, and traded.^[10] While the early French explorers that encountered the sites made no use of the metals due to the difficulties in transporting it,^[10] the copper was eventually traded throughout the continent along major river routes. In Manitoba, Canada, there also are ancient quartz mines near Waddy Lake and surrounding regions.^[11]

In the early colonial history of the Americas, “native gold and silver was quickly expropriated and sent back to Spain in fleets of gold- and silver-laden galleons”^[12] mostly from mines in Central and South America. Turquoise dated at 700 A.D. was mined in pre-ColumbianAmerica; in the Cerillos Mining District in New Mexico, estimates are that “about 15,000 tons of rock had been removed from Mt Chalchihuitl using stone tools before 1700.”^[13][14]

Mining in the United States became prevalent in the 19th century. As with the California Gold Rush in the mid 1800s, mining for minerals and precious metals, along with ranching, was a driving factor in the Westward Expansion to the Pacific coast. With the exploration of the West, mining camps were established and “expressed a distinctive spirit, an enduring legacy to the new nation;” Gold Rushers would experience the same problems as the Land Rushers of the transient West that preceded them.^[15] Aided by railroads, many traveled West for work opportunities in mining. Western cities such as Denver and Sacramento originated as mining towns.

[edit]Mining methods and procedures

[edit]Steps of mine development

The process of mining from discovery of an ore body through extraction of minerals and finally to returning the land to its natural state consists of several distinct steps. The first is discovery of the ore body, which is carried out through prospecting or exploration to find and then define the extent, location and value of the ore body. This leads to a mathematical resource estimation to estimate the size and grade of the deposit. This estimation is used to conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. The next step is to conduct a feasibility study to evaluate the financial viability, technical and financial risks and robustness of the project. This is when the mining company makes the decision to develop the mine or to walk away from the project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of the ore concentrates, engineering concerns, milling and infrastructure costs, finance and equity requirements and an analysis of the proposed mine from the initial excavation all the way through to reclamation. Once the analysis determines a given ore body is worth recovering, development begins to create access to the ore body. The mine buildings and processing plants are built and any necessary equipment is obtained. The operation of the mine to recover the ore begins and continues as long as the company operating the mine finds it economical to do so. Once all the ore that the mine can produce profitably is recovered, reclamation begins to make the land used by the mine suitable for future use.

[edit]Mining techniques

A minecart toilet, used inBisbee, Arizona.

Mining techniques can be divided into two common excavation types: surface mining and sub-surface (underground) mining. Mining targets are divided into two general categories of materials: placer deposits, consisting of valuable minerals contained within river gravels, beach sands, and other unconsolidated materials; and lode deposits, where valuable minerals are found in veins, in layers, or in mineral grains generally distributed throughout a mass of actual rock. Both types of ore deposit, placer or lode, are mined by both surface and underground methods.

Processing of placer ore material consists of gravity-dependent methods of separation, such as sluice boxes. Only minor shaking or washing may be necessary to disaggregate (unclump) the sands or gravels before processing. Processing of ore from a lode mine, whether it is a surface or subsurface mine, requires that the rock ore be crushed and pulverized before extraction of the valuable minerals begins. After lode ore is crushed, recovery of the valuable minerals is done by one, or a combination of several, mechanical and chemical techniques.

Some mining, including much of the uranium mining being done today, is done by less-common methods, such as in-situ leaching: this technique involves digging neither at the surface nor underground. The extraction of target minerals by this teqhnique requires that they be soluble, e.g., potash, potassium chloride, sodium chloride, sodium sulfate and uranium oxide which dissolve in water.^[16][17]

Surface mining is done by removing (stripping) surface vegetation, dirt, and if necessary, layers of bedrock in order to reach buried ore deposits. Techniques of surface mining include; Open-pit mining which consists of recovery of materials from an open pit in the ground, quarrying or gathering building materials from an open pit mine, strip mining which consists of stripping surface layers off to reveal ore/seams underneath, and Mountaintop removal, commonly associated with coal mining, which involves taking the top of a mountain off to reach ore deposits at depth. Most (but not all) placer deposits, because of their shallowly-buried nature, are mined by surface methods. Landfill miningfinally are sites where landfills are excavated and processed.^[18]

Open-pit mine near Garzweiler, Germany

Sub-surface mining consists of digging tunnels or shafts into the earth to reach buried ore deposits. Ore, for processing, and waste rock, for disposal, are brought to the surface through the tunnels and shafts. Sub-surface mining can be classified by the type of access shafts used, the extraction method or the technique used to reach the mineral deposit. Drift mining utilizes horizontal access tunnels, slope mining uses diagonally sloping access shafts and shaft mining consists of vertical access shafts. Other methods include shrinkage stope mining which is mining upward creating a sloping underground room, long wall mining which is grinding a long ore surface underground and room and pillar which is removing ore from rooms while leaving pillars in place to support the roof of the room. Room and pillar mining often leads to retreat mining which is removing the pillars which support rooms, allowing the room to cave in, loosening more ore. Additional sub-surface mining methods include Hard rock mining which is mining of hard materials, bore hole mining, drift and fill mining, long hole slope mining, sub level caving and block caving

[edit]Machinery

Gold-bearing gravels are shoveled into a trommel at the Blue Ribbon placer mine, Alaska.

Heavy machinery is needed in mining for exploration and development, to remove and stockpile overburden, to break and remove rocks of various hardness and toughness, to process the ore and for reclamation efforts after the mine is closed. Bulldozers, drills, explosives and trucks are all necessary for excavating the land. In the case of placer mining, unconsolidated gravel, or alluvium, is fed into machinery consisting of a hopper and a shaking screen or trommel which frees the desired minerals from the waste gravel. The minerals are then concentrated using sluices or jigs. Large drillsare used to sink shafts, excavate stopes and obtain samples for analysis. Trams are used to transport miners, minerals and waste. Lifts carry miners into and out of mines, as well as moving rock and ore out, and machinery in and out of underground mines. Huge trucks, shovels and cranes are employed in surface mining to move large quantities of overburden and ore. Processing plants can utilize large crushers, mills, reactors, roasters and other equipment to consolidate the mineral-rich material and extract the desired compounds and metals from the ore.

[edit]Extractive metallurgy

The science of extractive metallurgy is a specialized area in the science of metallurgy that studies the extraction of valuable metals from their ores, especially through chemical or mechanical means. Mineral processing (or mineral dressing) is a specialized area in the science of metallurgy that studies the mechanical means of crushing, grinding, and washing that enable the separation (extractive metallurgy) of valuable metals or minerals from their gangue (waste material). Since most metals are present in ores as oxides or sulfides, the metal needs to be reduced to its metallic form. This can be accomplished through chemical means such as smelting or through electrolytic reduction, as in the case of aluminum. Geometallurgycombines the geologic sciences with extractive metallurgy and mining.

[edit]Environmental effects

This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (November 2008)

House in Gladbeck, Germany, with fissures caused by gravity erosion due to mining

Environmental issues can include erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to increase the available room for the storage of the created debris and soil. ^[19] Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. ^[20] Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned to close to its original state. Some mining methods may have significant environmental and public health effects.

Iron hydroxide precipitate stains a stream receiving acid drainage from surface coal mining.

Mining can have adverse effects on surrounding surface and ground water if protective measures are not taken. The result can be unnaturally high concentrations of some chemicals, such as arsenic, sulfuric acid, and mercury over a significant area of surface or subsurface. ^[21] Runoff of mere soil or rock debris -although non-toxic- also devastates the surrounding vegetation. The dumping of the runoff in surface waters or in forests is the worst otion here.Submarine tailings disposal is regarded as a better option (if the soil is pumped to a great depth.^[22] Mere land storage and refilling of the mine after it has been depleted is, of course, even better; if no forests need to be cleared for the storage of the debris. There is potential for massive contamination of the area surrounding mines due to the various chemicals used in the mining process as well as the potentially damaging compounds and metals removed from the ground with the ore. Large amounts of water produced from mine drainage, mine cooling, aqueous extraction and other mining processes increases the potential for these chemicals to contaminate ground and surface water. In well-regulated mines, hydrologists and geologists take careful measurements of water and soil to exclude any type of water contamination that could be caused by the mine’s operations. The reducing or eliminating of environmental degradation is enforced in modern American mining by federal and state law, by restricting operators to meet standards for protecting surface and ground water from contamination. This is best done trough the use of non-toxic extraction processes as Bioleaching. If the project site besomes nonetheless polluted, mitigation techniques such as acid mine drainage (AMD) need to be performed.

The five principal technologies used to monitor and control water flow at mine sites are diversion systems, containment ponds, groundwater pumping systems, subsurface drainage systems, and subsurface barriers. In the case of AMD, contaminated water is generally pumped to a treatment facility that neutralizes the contaminants.^[23] Some examples of areas affected by acid mine drainage are the Berkeley Pit, and the Wheal Jane Mines.

Dissolution and transport of metals and heavy metals by run-off and ground water is another example of environmental problems with mining, such as the Britannia Mine, a former copper mine near Vancouver, British Columbia. Tar Creek, an abandoned mining area in Picher, Oklahoma that is now an Environmental Protection Agencysuperfund site, also suffers from heavy metal contamination. Water in the mine containing dissolved heavy metals such as lead and cadmium leaked into local groundwater, contaminating it.^[24] Long-term storage of tailings and dust can lead to additional problems, as they can be easily blown off site by wind, as occurred at Scouriotissa, an abandoned copper mine inCyprus. Erosion of exposed hillsides, mine dumps, tailings dams and resultant siltation of drainages, creeks and rivers can significantly impact the surrounding areas, a prime example being the giant Ok Tedi Mine in Papua New Guinea. In areas of wilderness mining may cause destruction and disturbance of ecosystems and habitats, and in areas of farming it may disturb or destroy productive grazing and croplands. In urbanised environments mining may produce noise pollution, dust pollution and visual pollution.

To ensure completion of reclamation, or restoring mine land for future use, many governments and regulatory authorities around the world require that mining companies post a bond to be held in escrow until productivity of reclaimed land has been convincingly demonstrated, although if cleanup procedures are more expensive than the size of the bond, the bond may simply be abandoned. Since 1978 the mining industry has reclaimed more than 2 million acres (8,000 km²) of land in the United States alone. This reclaimed land has renewed vegetation and wildlife in previous mining lands and can even be used for farming and ranching. For further reading on reclamation of former mining sites, please see Restoration ecology.

[edit]Mining industry

This section requires expansion.

While exploration and mining can sometimes be conducted by individual entrepreneurs or small business, most modern-day mines are large enterprises requiring large amounts of capital to establish. Consequently, the mining sector of the industry is dominated by large, often multinational, mostly publicly-listed companies. See Mining Companies for a list. However, what is referred to as the ‘mining industry’ is actually two sectors, one specializing in exploration for new resources, the other specializing in mining those resources. The exploration sector is typically made up of individuals and small mineral resource companies dependent on public investment. The mining sector is typically large and multi-national companies sustained by mineral production from their mining operations. In addition to these two sectors, various other industries such as equipment manufacture, environmental testing and metallurgy analysis also rely on and support the mining industry throughout the world.

[edit]Corporate classifications

Mining companies can be classified based on their size and financial capabilities:

• Major companies are considered to have an adjusted annual mining-related revenue of more than US$500 million, with the financial capability to develop a major mine on its own.

• Intermediate companies have at least $50 million in annual revenue but less than $500 million.

• Junior companies rely on equity financing as their principal means of funding exploration. Juniors are mainly pure exploration companies, but may also produce minimally, and do not have a revenue of US$50 million.^[25]

[edit]Safety

Danger sign at an old Arizona mine.

Safety has long been a controversial issue in the mining business especially with sub-surface mining. While mining today is substantially safer than it was in the previous decades, mining accidents are often very high profile, such as the Quecreek Mine Rescue saving 9 trapped Pennsylvania coal miners in 2002. Mining ventilation is a significant safety concern for many miners. Poor ventilation of the mines causes exposure to harmful gases, heat and dust inside sub-surface mines. These can cause harmful physiological effects, including death. The concentration of methane and other airborne contaminants underground can generally be controlled by dilution (ventilation), capture before entering the host air stream (methane drainage), or isolation (seals and stoppings).^[26] Ignited methane gas is a common source of explosions in coal mines, or, the more violent coal dust explosions. Gases in mines can also poison the workers or displace the oxygen in the mine, causing asphixiation.^[26] For this reason, the MHSA requires that workers have gas detection equipment in groups of miners. It must be able to detect common gases, such as CO, O2, H2S, and % Lower Explosive Limit. Additionally, further regulation is being requested for more gas detection as newer technology such as nanotechnology is introduced. High temperatures and humidity may result in heat-related illnesses, including heat stroke which can be fatal. Dusts can cause lung problems, includingsilicosis, asbestosis and pneumoconiosis (also known as miners lung or black lung disease). A ventilation system is set up to force a stream of air through the working areas of the mine. The air circulation necessary for the effective ventilation of a mine is generated by one or more large mine fans, usually located above ground. Air flows in one direction only, making circuits through the mine such that each main work area constantly receives a supply of fresh air.

Since mining entails removing dirt and rock from its natural location creating large empty pits, rooms and tunnels, cave-ins are a major concern within mines. Modern techniques for timbering and bracing walls and ceilings within sub-surface mines have reduced the number of fatalities due to cave-ins, but accidents still occur.^{[citation needed]} The presence of heavy equipment in confined spaces also poses a risk to miners, and in spite of modern improvements to safety practices, mining remains dangerous throughout the world.

[edit]Abandoned mines

Abandoned mine in Nevada.

There are upwards of 560,000 abandoned mines on public and privately owned lands in the United States alone.^[27][28] Abandoned mines pose a threat to anyone who may attempt to explore them without proper knowledge and safety training. Old mines are often dangerous and can contain deadly gases. Since weather may have eroded the earth and rock surrounding it, the entrance to an old mine in particular can be very dangerous. Old mine workings, caves, etc. are commonly hazardous simply due to the lack of oxygen in the air, a condition in mines known as blackdamp.

[edit]Hearing loss

Miners utilize equipment strong enough to break through extremely hard layers of the earth’s crust. This equipment, combined with the closed workspace that underground miners work in, can cause hearing loss.^[29] For example, a roof bolter (commonly used by mine roof bolter operators) can reach sound power levels of up to 115 dB.^[29] Combined with the reverberant effects of underground mines, a miner without proper hearing protection is not only at a high risk for hearing loss,^[29] but is also going against OSHA standards^[30].

[edit]Records

As of 2008, the deepest mine in the world is TauTona in Carletonville, South Africa at 3.9 kilometers^[31], replacing Savuka Mine in the North West Province of South Africa at 3,774 meters^[32]. East Rand Mine in Boksburg, South Africa briefly held the record at 3,585 meters, and the first mine declared the deepest in the world was also TauTona when it was at 3,581 meters. The deepest mine in Europe is Pyhäsalmi Mine in Pyhäjärvi, Finland at 1,444 meters. The second deepest mine in Europe is Boulby Mine England at 1,400 meters (shaft depth 1,100 meters)

The deepest open pit mine in the world is Bingham Canyon Mine in Bingham Canyon, Utah, United States at over 1,200 meters. The largest and second deepest open pit copper mine in the world is Chuquicamata in Chuquicamata, Chile at 900 meters, 940,600 tons of copper and 17,700 tons of molybdenum produced annually.^{[citation needed]}

The largest underground mine: El Teniente, in Rancagua, Chile, 2,400 kilometers of underground drifts, 418,000 tons of copper yearly. The deepest borehole in the world is Kola Superdeep Borehole at 12,262 meters. This, however, is not a matter of mining but rather related to scientific drilling.

[edit]See also

• Outline of mining
• Landfill mining
• List of uranium mines
• Canadian Mining Hall of Fame
• Exposure action value

[edit]References

[edit]External links

Look up mining in Wiktionary, the free dictionary.

• Glossary of terms
• Introduction to Mining
• What is mining?
• Mining

From Wikipedia, the free encyclopedia

A three dimensional model of an underground mine with shaft access

Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, mainly those minerals containing metals^[1] such as ore containing gold, copper, zinc, nickel and lead, but also involves using the same techniques for excavating ores of gems such as diamonds. In contrast soft rock mining refers to excavation of softer minerals such as salt, coal, or oil sands.

[edit]Mine access

[edit]Underground access

Accessing underground ore can be achieved via a decline (ramp), inclined vertical shaft or adit.

• Declines can be a spiral tunnel which circles either the flank of the deposit or circles around the deposit. The decline begins with a box cut, which is the portal to the surface. Depending on the amount of overburden and quality of bedrock, a galvanized steel culvert may be required for safety purposes. They may also be started into the wall of an open cutmine.

• Shafts are vertical excavations sunk adjacent to an ore body. Shafts are sunk for ore bodies where haulage to surface via truck is not economical. Shaft haulage is more economical than truck haulage at depth, and a mine may have both a decline and a ramp.

• Adits are horizontal excavations into the side of a hill or mountain. They are used for horizontal or near-horizontal ore bodies where there is no need for a ramp or shaft.

Declines are often started from the side of the high wall of an open cut mine when the ore body is of a payable grade sufficient to support an underground mining operation but the strip ratio has become too great to support open cast extraction methods.

[edit]Ore access

Levels are excavated horizontally off the decline or shaft to access the ore body. Stopes are then excavated perpendicular (or near perpendicular) to the level into the ore.

[edit]Development mining vs. production mining

There are two principal phases of underground mining: development mining and production mining.

Development mining is composed of excavation almost entirely in (non-valuable) waste rock in order to gain access to the orebody. There are five steps in development mining: remove previously blasted material (muck out round), drill rock face, load explosives, blast explosives, and support excavation.

Production mining is further broken down into two methods, long hole and short hole. Short hole mining is similar to development mining, except that it occurs in ore. There are several different methods of long hole mining. Typically long hole mining requires two excavations within the ore at different elevations below surface, (15 m – 30 m apart). Holes are drilled between the two excavations and loaded with explosives. The holes are blasted and the ore is removed from the bottom excavation.

[edit]Ventilation

Door for directing ventilation in an old lead mine. The ore hopper at the front is not part of the ventilation.

One of the most important aspects of underground hard rock mining is ventilation. Ventilation is required to clear toxic fumes from blasting and removing exhaust fumes from diesel equipment. In deep hot mines ventilation is also required for cooling the workplace for miners. Ventilation raises are excavated to provide ventilation for the workplaces, and can be modified for use as emergency escape routes. The primary sources of heat in underground hard rock mines are virgin rock temperature, machinery, auto compression, and fissure water. Other small contributing factors are human body heat and blasting.

[edit]Ground support

Some means of support is required in order to maintain the stability of the openings that are excavated. This support comes in two forms, local support and area support.

[edit]Area ground support

Area ground support is used to prevent major ground failure. Holes are drilled into the back (ceiling) and walls and a long metal bar (or rock bolt) is installed to hold the ground together. There are three categories of rock bolt, determined on the way the behave in the rock.^[2] They are:

[edit]Mechanical bolts

• Point anchor bolts (or expansion shell bolts) are a common style of area ground support. A point anchor bolt is a metal bar between 20 mm – 25 mm in diameter, and between 1 m – 4 m in length (the size is determined by the mine’s engineering department). There is an expansion shell at the end of the bolt which is inserted into the hole. As the bolt is tightened by the installation drill the expansion shell expands and the bolt tightens holding the rock together. Mechanical bolts are considered temporary support as their lifespan is reduced by corrosion as they are not grouted.^[2]

[edit]Grouted bolts

• Resin grouted rebar is used in areas which require more support than a point anchor bolt can give. The rebar used is of similar size as a point anchor bolt but does not have an expansion shell. Once the hole for the rebar is drilled, cartridges of epoxy resin are installed in the hole. The rebar bolt is installed after the resin and spun by the installation drill. This opens the resin cartridge and mixes it. Once the resin hardens the drill spinning tightens the rebar bolt holding the rock together. Resin grouted rebar is considered a permanent ground support with a lifespan of 20–30 years.^[2]
• Cable bolts are used to bind large masses of rock in the hanging wall and around large excavations. Cable bolts are much larger than standard rock bolts and rebar, usually between 10–25 metres long. Cable bolts are grouted with a cement grout.^[2]

[edit]Friction bolts

• Split-sets are much easier to install than mechanical bolts or grouted bolts. The bolt is hammered into the drill hole, which has a smaller diameter than the bolt. Pressure from the bolt on the wall holds the rock together. Split-set bolts are particularly susceptible to corrosion and rust from water unless they are grouted. Once grouted the friction increases by a factor of 3-4.^[2]
• Swellex is similar to a split-set, except the bolt diameter is smaller than the hole diameter. High pressure water is injected into the bolt to expand the bolt diameter to hold the rock together. Like the split-set, swellex is poorly protected from corrosion and rust.^[2]

[edit]Local ground support

Local ground support is used to prevent smaller rocks from falling from the backs and walls. Not all excavations require local ground support.

• Welded Wire Mesh is a metal screen with 10 cm x 10 cm (4 inch) openings. It is held to the backs using point anchor bolts or resin grouted rebar.
• Shotcrete is a spray on concrete which coats the backs and walls preventing smaller rocks from falling. Shotcrete thickness can be between 50 mm – 100 mm.
• Latex Membranes can be sprayed on the backs and walls similar to shotcrete, but in smaller amounts.

[edit]Stope and retreat vs. stope and fill

[edit]Stope and retreat

Sub-Level Caving Subsidencereaches surface at the Ridgeway underground mine.

Using this method, mining is planned to extract rock from the stopes without filling the voids; this allows the wall rocks to cave in to the extracted stope after all the ore has been removed. The stope is then sealed to prevent access.

[edit]Stope and fill

Where large bulk ore bodies are to be mined at great depth, or where leaving pillars of ore is uneconomical, the open stope is filled with backfill, which can be a cement and rock mixture, a cement and sand mixture or a cement and tailings mixture. This method is popular as the refilled stopes provide support for the adjacent stopes, allowing total extraction of economic resources.

[edit]Mining methods

Schematic diagram of Cut and Fill mining

[edit]Selective mining methods

• Cut and Fill mining is a method of short hole mining used steeply dipping or irregular ore zones, in particular where the hanging wall limits the use of long hole methods. The ore is mined in horizontal or slightly inclined slices, and filled with waste rock, sand or tailings. Either fill option may be consolidated with concrete, or left unconsolidated. Cut and fill mining is an expensive but selective method, with low ore loss and dilution.^[3]

• Drift and Fill is similar to cut and fill, except it is used in ore zones which are wider than the method of drifting will allow to be mined. In this case the first drift is developed in the ore, and is backfilled using consolidated fill. The second drift is driven adjacent to the first drift. This carries on until the ore zone is mined out to its full width, at which time the second cut is started atop of the first cut.

• Shrinkage Stoping is a short hole mining method which is suitable for steeply dipping orebodies. The method is similar to cut and fill mining with the exception that after being blasted, broken ore is left in the stope where it is used to support the surrounding rock and as a platform to work off of. Only enough ore is removed from the stope to allow for drilling and blasting the next slice. The stope is emptied when all of the ore has been blasted. Although it is very selective and allows for low dilution, since the most of the ore stays in the stope until mining is completed there is a delayed return on capital investments.^[3]

• Room and Pillar mining : Room and pillar mining is commonly done in flat or gently dipping bedded ore bodies. Pillars are left in place in a regular pattern while the rooms are mined out. In many room and pillar mines, the pillars are taken out starting at the farthest point from the stope access, allowing the roof to collapse and fill in the stope. This allows a greater recovery as less ore is left behind in pillars.

[edit]Bulk mining methods

• Block Caving is used to mine massive steeply dipping orebodies (typically low grade) with high friability. An undercut with haulage access is driven under the orebody, with “drawbells” excavated over the undercut. The drawbells serve as a place for caving rock to fall into. The orebody is drilled and blasted above the undercut, and the ore is removed via the haulage access. Due to the friability of the orebody the ore above the first blast caves and falls into the drawbells. As ore is removed from the drawbells the orebody caves in providing a steady stream of ore.^[3] If caving stops and removal of ore from the drawbells continues, a large void may form, resulting in the potential for a sudden and massive collapse and potentially catastrophic windblast throughout the mine.^[4]

[edit]Ore removal

In mines which use rubber tired equipment for coarse ore removal, the ore is removed from the stope (referred to as “mucked out” or “bogged”) using center articulated vehicles (referred to as boggers or LHD [short for Load, Haul, Dump]). These pieces of equipment may operate using diesel or electric engines and resemble a low-profile front end loader.

The ore is then dumped into a truck to be hauled to the surface (in shallower mines). In deeper mines the ore is dumped down an ore pass (a vertical or near vertical excavation) where it falls to a collection level. On the collection level, it may receive primary crushing via jaw or cone crusher. The ore is then moved by conveyor belts, trucks or occasionally trains to the shaftto be hoisted to the surface in buckets or skips and emptied into bins beneath the surface headframe for transport to the mill.

In some cases the underground primary crusher feeds an inclined conveyor belt which delivers ore via an incline shaft direct to the surface. The ore is fed down ore passes, with mining equipment accessing the ore body via a decline from surface.

[edit]Deepest mines

• The deepest mines in the world are the TauTona (Western Deep Levels) and Savuka gold mines in the Witwatersrand region of South Africa, which are currently working at depths exceeding 3,900 meters (about 12,800 feet ). ^[5] There are plans to extend Mponeng ming, a sister mine to TauTona, down to 4,500 meters in the coming years.^{[citation needed]}
• The deepest hard rock mine in North America is Xstrata’s Kidd Mine, which mines copper and zinc ore in Timmins, Ontario. Mining is actively occurring 2,682 m (8,800 feet) below surface. The shaft bottoms out at over 2,926m (9,600 feet) down.
• The deepest hard rock mines in Australia are the copper and zinc lead mines in Mount Isa, Queensland at 1,800 m (5,906 feet).
• The deepest platinum-palladium mines in the world are on the Merensky Reef, in South Africa, with a resource of 203 million Troy ounces, currently worked to approximately 2,200 m (7,218 feet) depth.
• The harshest conditions for hard rock mining are in the Witwatersrand area of South Africa, where workers toil in temperatures of up to 45 °C (113 °F). However, massive refrigeration plants are used to bring the air temperature down to around 28 °C.

[edit]Footnotes

[edit]See also

• Adit
• Gold mining
• Mining
• Shaft Mining
• Mining Act of 1872

Geotehnoloogia geotehnoloogia veebis