Phoenix City Yalu River Boiler Manufacturing

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engineered floating floor

cork floor tile

   Phoenix City Yalu River is the provincial certification atmospheric pressure boiler plant boiler manufacturing enterprises, Liaoning Fengcheng a professional production of new environmentally friendly boiler manufacturers, phoenix city of high-tech enterprise. Enterprise was founded in 1982, is located in the beautiful state-level scenic spot - at the foot of Phoenix Mountain, away from the Sino-Korean border city of Dandong, 50 km. Company covers an area of 5,000 square meters, construction area of 1,200 square meters. The main products is the production of legislation, Horizontal with different specifications, models and has a new high-tech environmentally friendly boilers. carbonized bamboo flooring

Domestic power station equipment

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    In 2008 the building of the country's electricity market capacity, how much? Relevant survey shows that the scale of the National Power Construction Investment about 3,000 billion yuan, added installed capacity of 90 million kilowatts. Grid scale of construction is also about 300 billion yuan. Both the sum of 6,000 billion big market. This electrical equipment manufacturers will undoubtedly be good news.

However, there are indications that the construction market in the power, under an optimistic situation, there are still worries. wrist rest pad

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    Power building has been installed down gel wrist pad

Statistics show that in 2007 the country put into operation new installed capacity of 100.09 million kilowatts of electricity, of which hydropower installed capacity reached 13.065 million kilowatts of thermal power installed capacity reached 81.5835 million kilowatts of wind power installed capacity reached 2.9617 million kilowatts. Installed capacity of 90 million kilowatts this year is expected, slightly lower than the previous two years.

Looking power this year, building markets, the main power station auxiliary equipment manufacturing enterprises are still optimistic about a year.



Power station equipment manufacturing industry a high degree of concentration, whether it is the host device, or auxiliary equipment alike. Along with the rapid development of electric power construction, power plant equipment manufacturing business R & D capabilities and a substantial increase in the scale of production, coupled with the high threshold, high-tech, high-input industry characteristics, in the already relatively concentrated state more concentrated way.



    At present, the power installed capacity growing more and more large-capacity building. Host-plant basic control unit capacity of 60 million KW, over control of cogeneration unit of 30 million KW. Compared with the low capacity of the units available to share the "cake" relatively reduced. In other words, the power-building market, power plant equipment manufacturing orders for the host basically Shanghai Electric, Harbin Power Group, Dongfang Electric Power Plant of the three, as well as Beijing Babcock & Wilcox, North weight and Wuhan Boiler, South steamship and other second-tier business.



It is worth mentioning that the power plant equipment manufacturing cycle is relatively long, the crew put into operation in 2008 that about 50% above 2007 or an earlier period of order, some of the equipment is now in production manufacturing. Power Station Auxiliary Equipment products relative to the host plant production cycle should be shorter, but there are a considerable part of the 2007 orders. Thus, 3000 billion construction market power does not truly reflect the current market resources, capacity, power supply construction market as a whole tends to decline.



    Desulfurization equipment, a significant market capacity

In recent years, environmental protection equipment market space station continued to grow. Along with the increased intensity of energy-saving emission reduction, in addition to manufacturing the conventional power station dust removal, desulfurization equipment, the electrical denitration device into a new economic growth point. According to statistics, in 2004 the domestic desulfurization equipment manufacturing enterprises is only seventy to eighty home has more than 100 by 2007. At present, more than a dozen companies to enter the engineering field denitrification.



According to the U.S. Electric Power Research departments of 121 coal-fired power plant FGD project, the U.S. power plant desulfurization equipment accounted for about 15% of the total investment. It is learned that the domestic cost of desulfurization equipment, relatively low, accounting for about 10% of investment than out, as technology continues to mature, to participate in the increase, there will be room for downward adjustment.

Domestic 2 30-million KW, for example, desulfurization equipment needs invested about 2 billion yuan; 2 60 MW units, need to invest money is up from 400 million to 500 million yuan. Only the power plant desulfurization equipment market resources are considerable. Combined with power plant denitration equipment market, is a not a small market capacity.

Coffee roasting

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Process

The coffee roasting process consists essentially of sorting, roasting, cooling, and packaging operations but can also include grinding in larger scale roasting houses. In larger operations, bags of green coffee beans are hand or machine-opened, dumped into a hopper, and screened to remove debris. The green beans are then weighed and transferred by belt or pneumatic conveyor to storage hoppers. From the storage hoppers, the green beans are conveyed to the roaster. Roasters typically operate at temperatures between 370 and 540 F (188 and 282 C), and the beans are roasted for a period of time ranging from 3 to 30 minutes. Roasters are typically horizontal rotating drums that are heated from below and tumble the green coffee beans in a current of hot gases. The heat source can be supplied by natural gas, liquefied petroleum gas (LPG), electricity or even wood. These roasters can operate in either batch or continuous modes and can be indirect- or direct-fired.

Those who roast coffee often prefer to follow a "recipe" or "roast profile" to highlight certain flavor characteristics. Any number of factors may help a person determine the best profile to use, such as the coffee's origin, varietal, processing method or desired flavor characteristics. A roast profile can be presented as a graph showing time on one axis and temperature on the other, which can be recorded manually or using computer software and data loggers linked to temperature probes inside various parts of the roaster. abrasive blasting equipment

Indirect-fired roasters are roasters in which the burner flame does not contact the coffee beans, although the combustion gases from the burner do contact the beans. Direct-fired roasters contact the beans with the burner flame and the combustion gases. At the end of the roasting cycle, the roasted beans are cooled using a vacuum system. Roasted coffee beans are also cooled using fine water mist, which is known as "quenching" and is considered inferior to air cooling as the water soaks the fresh beans with moisture and oxygen particles making it stale almost instantly. Following roasting, the beans are cooled and stabilized. This stabilization process is called degassing. Following degassing, the roasted beans are packaged, usually in light-resistant foil bags fitted with small one-way valves to allow gasses to escape while protecting the beans from moisture and oxygen. Roasted whole beans can be considered fresh for up to one month. Once coffee is ground it is best used immediately. crankshaft grinding

Packaging cnc water jet

Extending the useful life of roasted coffee relies on maintaining an optimum environment for the beans. The first large scale preservation technique was vacuum packing. However, because coffee emits CO2 after roasting, coffee to be vacuum packed must be allowed to degas for several days before it is sealed. To allow more immediate packaging, pressurized canisters or foil-lined bags with pressure-relief valves can be used.

Darkness

As the bean absorbs heat, the color shifts to yellow and then to varying shades of brown. During the later stages of roasting, oils appear on the surface of the bean, making it shiny. The roast will continue to darken until it is removed from the heat source. At lighter roasts, the bean will exhibit more of its "origin flavor" - the flavors created in the bean by the soil and weather conditions in the location where it was grown.

Coffee beans from famous regions like Java, Kenya, Hawaiian Kona, and Jamaican Blue Mountain are usually roasted lightly so their signature characteristics dominate the flavor. As the beans darken to a deep brown, the origin flavors of the bean are eclipsed by the flavors created by the roasting process itself. At darker roasts, the "roast flavor" is so dominant that it can be difficult to distinguish the origin of the beans used in the roast.

Below, roast levels and their respective flavors are described. These are qualitative descriptions, and thus subjective. As a rule of thumb, the "shinier" the bean is, the more dominant the roasting flavors are.

Roast level

Notes

Surface

Flavor

Light

Cinnamon roast, half city, New England

After several minutes the beans op or "crack" and visibly expand in size. This stage is called first crack. American mass-market roasters typically stop here.

Dry

Lighter-bodied, higher acidity, no obvious roast flavor

Medium

Full city, American, regular, breakfast, brown

After a few short minutes the beans reach this roast, which U.S. specialty sellers tend to prefer.

Dry

Sweeter than light roast; more body exhibiting more balance in acid, aroma, and complexity.

Full Roast

High, Viennese, Italian Espresso, Continental

After a few more minutes the beans begin popping again, and oils rise to the surface. This is called second crack.

Slightly shiny

Somewhat spicy; complexity is traded for heavier body/mouth-feel. Aromas and flavors of roast become clearly evident.

Double Roast

French

After a few more minutes or so the beans begin to smoke. The bean sugars begin to carbonize.

Very oily

Smokey-sweet; light bodied, but quite intense. None of the inherent flavors of the bean are recognisable.

Grades of coffee roasting; from left: unroasted (or "green"), light, cinnamon, medium, high, city, full city, Italian, and French.

Home roasting

Main article: Home roasting coffee

Home roasting is the process of roasting small batches of green coffee beans for personal consumption. Roasting coffee in the home is something that has been practiced for centuries, and has included methods such as heating over fire coals, roasting in cast iron pans, and rotating iron drums over a fire or coal bed. Computerized drum roasters are available which simplify home roasting and some home roasters simply roast in an oven or in air popcorn poppers.

Up until the 20th century, it was more common for at-home coffee drinkers to roast their coffee in their residence than it was to buy roasted coffee. During the 20th century, home roasting faded in popularity with the rise of the commercial coffee roasting companies. In recent years home roasting of coffee has seen a revival. In some cases there is an economic advantage, but primarily it is a means to achieve finer control over the quality and characteristics of the finished product.

Emissions and control

Particulate matter (PM), volatile organic compounds (VOC), organic acids, and combustion products are the principal emissions from coffee processing. Several operations are sources of PM emissions, including the cleaning and destoning equipment, roaster, cooler, and instant coffee drying equipment. The roaster is the main source of gaseous pollutants, including alcohols, aldehydes, organic acids, and nitrogen and sulfur compounds. Because roasters are typically natural gas-fired, carbon monoxide (CO) and carbon dioxide (CO2) emissions result from fuel combustion. Decaffeination and instant coffee extraction and drying operations may also be sources of small amounts of VOC. Emissions from the grinding and packaging operations typically are not vented to the atmosphere.

Particulate matter emissions from the roasting and cooling operations are typically ducted to cyclones before being emitted to the atmosphere. Gaseous emissions from roasting operations are typically ducted to a thermal oxidiser or thermal catalytic oxidiser following PM removal by a cyclone. Some facilities use the burners that heat the roaster as thermal oxidisers. However, separate thermal oxidisers are more efficient because the desired operating temperature is typically between 650C and 816C (1200F and 1500F), which is 93C to 260C (200F to 500F) more than the maximum temperature of most roasters. Some facilities use thermal catalytic oxidizers, which require lower operating temperatures to achieve control efficiencies that are equivalent to standard thermal oxidisers. Catalysts are also used to improve the control efficiency of systems in which the roaster exhaust is ducted to the burners that heat the roaster. Emissions from spray dryers are typically controlled by a cyclone followed by a wet scrubber.

Gallery

Unroasted coffee beans at various stages L: one year after drying, after drying, fresh picked.

Unroasted coffee beans at later stages. The beans are 7 and 8 years old.

An old large-capacity coffee roaster made from cast iron.

An example of lighter roasted, versus darker roasted beans. The degree of roasting which is ideal for coffee in general, and a given varietal or blend is highly subjective.

See also

Coffee

Dry roasting

French press

Torrefacto

v  d  e

Coffee

Production by country

Brazil  Colombia  Costa Rica  Ecuador  El Salvador  Ethiopia  Guatemala  Haiti  India  Indonesia  Jamaica  Kenya  Papua New Guinea  Philippines   USA  Vietnam

Coffee topics

History of coffee  Economics of coffee  Coffee and health  Coffee and the environment

Species and varieties

List of varieties  Coffea arabica: Kenya AA, Kona, Jamaican Blue Mountain  Coffea canephora (Coffea robusta): Kopi Luwak  Coffea liberica: Kape Barako  Single-origin

Major chemicals in coffee

Cafestol  Caffeic acid  Caffeine

Coffee processing

Coffee roasting  Decaffeination  Home roasting coffee

Coffee preparation

Coffeemaker  Coffee percolator  Espresso (lungo, ristretto)  Espresso machine  Drip brew  French press  Turkish coffee  Vacuum coffee maker  Instant coffee  Chemex  Moka pot  AeroPress  Presso  Knockbox

Popular coffee beverages

Affogato  Americano  Bicerin  C ph s   Caf au lait  Caf con leche  Caf Cubano  Cafe mocha  Caff corretto  Caff macchiato  Cappuccino  Carajillo  Coffee milk  Cortado  Espresso  Flat white  Frappuccino  Galo  Greek frapp coffee  Iced coffee  Indian filter coffee  Ipoh white coffee  Irish coffee  Latte  Latte macchiato  Liqueur coffee  Long black  Red eye  Ristretto

Coffee substitutes

Barley tea  Barleycup  Caro  Chicory  Dandelion coffee  Pero  Postum  Roasted grain beverage

Coffee and lifestyle

Barista  Caf  Caff  Caff sospeso  Coffee break  Coffee ceremony  Coffee culture  Coffee cupping  Coffee Palace  Coffeehouse  Fika  Kopi tiam  List of coffeehouse chains  Viennese caf

Notes and references

^ Spiller, Gene (9 October 1997). Caffeine. Los Altos, California, USA: SPHERA Foundation. pp. 85. doi:http://books.google.nl/books?hl=nl&lr=&id=Rgs_rVOceZwC&oi=fnd&pg=PA79&dq=darkness+coffee+roasting+full+city&ots=Ev9xikg8-G&sig=bsEFmf_McYD-vZllruUuMdsErFc#v=onepage&q=full%20city&f=false. ISBN 9780849326479. 

^ "Strong, or just burnt?", "Roast & Post". Accessed October 7, 2008.

^ Thompson, Tom (2009). "An Updated Pictorial Guide to the Roast Process". http://www.sweetmarias.com/roasting-VisualGuideV2.php. Retrieved 12 Januari 2010. 

^ http://www.epa.gov/ttn/chief/ap42/ch09/final/c9s13-2.pdf

Categories: Coffee preparation

Mining

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History

Prehistoric mining

Chalcolithic copper mine in Timna Valley, Negev Desert, Israel. portable power inverter

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. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves are 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. cobra power inverter

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. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. itx power supply

Ancient Egypt

Ancient Egyptians mined malachite at Maadi. 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." Quarries for turquoise and copper were also found at "Wadi Hamamat, Tura, Aswan and various other Nubian sites" 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.

Ancient Greece and Rome

Agricola, author of De Re Metallica

Drainage wheel from Rio Tinto mines

Mining in Europe has a very long history, 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 washing comminuted 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 at Las 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 mined minerals for millennia , 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, especially reverse 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.

Medieval Europe

Mining as an industry underwent dramatic changes in medieval Europe. The mining industry in the early Middle Ages was mainly focused on the extraction of copper, bronze and iron. Other precious metals were also used mainly for gilding or coinage. Initially, many metals were obtained through open-pit mining, and ore was primarily extracted from shallow depths, rather than though the digging of deep mine shafts. Around approximately the 14th century, the demand for weapons, armor, stirrups, and horseshoes greatly increased the demand for iron. Medieval knights for example were often laden with up to 100 pounds of plate or chain link armor in addition to swords, lances and other weapons. The overwhelming dependency on iron for military purposes helped to spur increased iron production and extraction processes.

These new military applications coincided with a population explosion throughout Europe in the 11th-14th centuries which enriched the demand for precious metals in order to fill a currency shortage. The silver crisis of 1465 occurred when the mines had all reached depths at which the shafts could no longer be pumped dry with the available technology. Although the increased use of bank notes and the use of credit during this period did decrease the dependence and value of precious metals, these forms of currency still remained vital to the story of medieval mining. 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 Selmecbnya, Kingdom of Hungary (present-day Bansk tiavnica,Slovakia) in 1627. Black powder allowed blasting of rock and earth to loosen and reveal ore veins, which was much faster than fire-setting, in which rock was exposed to heat and then doused with cold water. Black powder allowed the mining of previously impenetrable metals and ores. In 1762, the world's first mining academy was established in the same town. Prior to this invention much mining was accomplished through firesetting. This method began by exposing the vein to prolonged heat from a fire.

The widespread adoption of agricultural innovations such as the iron plowshare, in addition to the growing usage of metal in architecture and building structure were also driving forces in the tremendous growth of the iron industry during this period. Inventions like the arrastra were often used by the Spanish to pulverize ore after being mined. This device employed animal power and utilized mechanical principles similar to that of the ancient Middle Eastern technology of grain threshing.

Much of our knowledge of Medieval mining techniques comes from books such as Biringuccio Pirotechnia and probably most importantly from Georg Agricola De Re Metallica (1556). These books detail many different mining methods used in German and Saxon mines. One of the prime issues dealt with by medieval miners (and one which Agricola explains in detail) was the removal of water from mining shafts. As miners dug deeper to access new veins, flooding became a very real obstacle. As a result the mining industry became dramatically more efficient and prosperous as the use of various mechanical and animal driven pump systems were implemented.

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. "Indians availed themselves of this copper starting at least 5000 years ago," 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. While the early French explorers that encountered the sites made no use of the metals due to the difficulties in transporting it, 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.

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" mostly from mines in Central and South America. Turquoise dated at 700 A.D. was mined in pre-Columbian America; 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."

Mining in the United States became prevalent in the 19th century, and the General Mining Act of 1872 was passed to encourage mining of federal lands. 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. Aided by railroads, many traveled West for work opportunities in mining. Western cities such as Denver and Sacramento originated as mining towns.

Mining methods and procedures

Steps of mine development

Simplified world mining map (click to enlarge)

Another simplified world mining map (click to enlarge)

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.

Mining techniques

A minecart toilet, used in Bisbee, Arizona.

Mining techniques can be divided into two common excavation types: surface mining and sub-surface (underground) mining. Surface mining is much more common, and produces, for example, 85% of minerals (excluding petroleum and natural gas) in the United States, including 98% of metallic ores. 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 and mining for rare earth elements 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.

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 mining finally are sites where landfills are excavated and processed.

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

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 drills are 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.

Extractive metallurgy

Main article: 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. Geometallurgy combines the geologic sciences with extractive metallurgy and mining.

Environmental effects

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

Main article: Environmental issues with 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. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. Mining companies in many countries may be required to follow environmental and rehabilitation codes; however, in many areas regulation is not enforced, and mining companies have encouraged self-policing. In 1992 a Draft Code of Conduct for Transnational Corporations was proposed at the Rio Earth Summit by the UN Centre for Transnational Corporations (UNCTC), but the Business Council for Sustainable Development (BCSD) together with the International Chamber of Commerce (ICC) argued successfully for self-regulation instead. This was followed up by the Global Mining Initiative which created of the International Council on Mining and Metals, an industry organization which works to self-regulate the mining industry internationally. The mining industry has provided funding to various nonprofit groups, which have been subsequently less inclined to fight for the rights of indigenous people.

Ore mills generate large amounts of waste, called tailings, which are perhaps their largest environmental burden. For example, 99 tonnes of waste are generated per tonne of copper, with even higher ratios in gold mining. These tailings can be toxic. Tailings, which are usually produced as a slurry, are most commonly dumped into ponds made from naturally-existing valleys. These ponds are secured by impoundments (dams or embankment dams). In 2000 it was estimated that 3,500 tailings impoundments existed, and that every year, 2 to 5 major failures and 35 minor failures occurred; for example, in the Marcopper mining disaster at least 2 million tons of tailings were released into a local river. Subaqueous tailings disposal is another option. The mining industry has argued that submarine tailings disposal (STD), which disposes of tailings in the sea, is ideal because it avoids the risks of tailings ponds; although the practice is illegal in the United States and Canada, it is used in the developing world.

Certification of mines with good practices occurs through the International Organization for Standardization (ISO) such as ISO 9000 and ISO 14001, which certifies an 'auditable environmental management system'; this certification involves short inspections, although it has been accused of lacking rigor.:183-4 Certification is also available through Ceres' Global Reporting Initiative, but these reports are voluntary and unverified. Miscellaneous other certification programs exist for various projects, typically through nonprofit groups.:185-6

Regulations and World Bank relationship

The World Bank has been involved in mining since 1955, mainly through grants from its International Bank for Reconstruction and Development, with the Bank's Multilateral Investment Guarantee Agency offering political risk insurance. Between 1955 and 1990 it provided about $2 billion to fifty mining projects, broadly categorized as reform and rehabilitation, greenfield mine construction, mineral processing, technical assistance, and engineering. These projects have been criticized, particularly the Ferro Carajas project of Brazil, began in 1981. The bank established mining codes intended to increase foreign investment, in 1988 solicited feedback from 45 mining companies on how to increase their involvement.:20

In 1992 the bank began to push for privatization of government-owned mining companies with a new set of codes, beginning with its report The Strategy for African Mining. In 1997, Latin America's largest miner Companhia Vale do Rio Doce (CVRD) was privatized. These and other movements such as the Philippines 1995 Mining Act led the World Bank to publish a third report (Assistance for Minerals Sector Development and Reform in Member Countries) which endorsed mandatory environment impact assessments and attention to the locals. The codes based on this report are influential in the legislation of developing nations. The new codes are intended to encourage development through tax holidays, zero custom duties, reduced income taxes, and related measures.:22 The results of these codes were analyzed by a group from the University of Quebec, which concluded that the codes promote foreign investment but "fall very short of permitting sustainable development". The observed negative effect of natural resources on economic development is known as the resource curse.

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.

Mining operations can be grouped into five major categories in terms of their respective resources. These are, oil and gas extraction, coal mining, metal ore mining, nonmetallic mineral mining and quarrying, and support activities for mining. Out of all these categories oil and gas extraction remains one of the largest in terms of its global economic importance. Prospecting potential mining sites, a vital area of concern for the mining industry is now done using sophisticated new technologies such as seismic prospecting and remote-sensing satellites.

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.

Safety

Danger sign at an old Arizona mine.

Abandoned mine entrance in Yorkshire, England

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). 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. 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, including silicosis, 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 despite modern improvements to safety practices, mining remains dangerous throughout the world.

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. 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. Standing water in mines from seepage or infiltration poses a significant hazard as the water can hide deep pits and trap gases below the water. Additionally, 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.

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. For example, a roof bolter (commonly used by mine roof bolter operators) can reach sound power levels of up to 115 dB. Combined with the reverberant effects of underground mines, a miner without proper hearing protection is not only at a high risk for hearing loss, but is also going against OSHA standards.

Records

As of 2008, the deepest mine in the world is TauTona in Carletonville, South Africa at 3.9 kilometers, replacing Savuka Mine in the North West Province of South Africa at 3,774 meters. 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 Pyhsalmi Mine in Pyhjrvi, 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 deepest open pit mine with respect to sea level is Tagebau Hambach in Germany, the ground of the pit is 293 meters below sea level.

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.

See also

Outline of mining

Mining and metallurgy in medieval Europe

Mining in Cornwall and Devon

Landfill mining

List of uranium mines

Canadian Mining Hall of Fame

National Mining Hall of Fame (USA)

Mineral industry

Spoil tip

References

^ Hartman, Howard L. SME Mining Engineering Handbook, Society for Mining, Metallurgy, and Exploration Inc, 1992, p3.

^ Swaziland Natural Trust Commission, "Cultural Resources - Malolotja Archaeology, Lion Cavern," Retrieved August 27, 2007, .

^ Peace Parks Foundation, "Major Features: Cultural Importance." Republic of South Africa: Author. Retrieved August 27, 2007, .

^ Shaw, I. (2000). The Oxford History of Ancient Egypt. New York: Oxford University Press, pp. 57-59.

^ a b Shaw, I. (2000). The Oxford History of Ancient Egypt. New York: Oxford University Press, p. 108.

^ The Independent, 20 Jan. 2007: The end of a Celtic tradition: the last gold miner in Wales

^ The Romans in Britain: mining

^ A culture of Improvement. Robert Friedel. MIT Press. 2007. Pg.81

^ Medieval Science and Technology: Original Essays.Medieval Iron and Steel Simplified Hall, Bert http://www.the-orb.net/encyclop/culture/scitech/iron_steel.html

^ http://mygeologypage.ucdavis.edu/cowen/~GEL115/115CH7.html

^ Heiss, A.G. & Oeggl, K. (2008). Analysis of the fuel wood used in Late Bronze Age and Early Iron Age copper mining sites of the Schwaz and Brixlegg area (Tyrol, Austria). Vegetation History and Archaeobotany 17(2):211-221, Springer Berlin / Heidelberg, .

^ The use of Firesetting in the Granite Quarries of South India Paul T. Craddock The Bulletin of the Peak District Mines Historical Society, Vol. 13 Number 1. 1996

^ The Spanish Tradition in Gold and Silver Mining. Otis E. Young Arizona and the West, Vol. 7, No. 4 (Winter, 1965), pp. 299-314 Journal of the Southwest Stable URL: http://www.jstor.org/stable/40167137.

^ a b Lankton, L. (1991). Cradle to Grave: Life, Work, and Death at the Lake Superior Copper Mines. New York: Oxford University Press, p. 5-6.

^ a b c West, G.A. (1970). Copper: its mining and use by the aborigines of the Lake Superior Region. Westport, Conn: Greenwood Press.

^ Bruno, L. & Heaman, L.M. (2004). Structural controls on hypozonal oroganic gold mineralization in the La Rouge Domain, Trans-Hudson Orogen, Saskatchewan. The Canadian Journal of Earth Sciences, Vol. 41, Issue 12, pp. 1453-1471.

^ Vaden, H.E. & Prevost. G. (2002). Politics of Latin America: The Power Game. New York: Oxford University Press, p. 34.

^ Maynard, S.R., Lisenbee, A.L. & Rogers, J. (2002). Preliminary Geologic Map of the Picture Rock 7.5 - Minute Quadrangle Sante Fe County, Central New Mexico. New Mexico Bureau of Geology and Mineral Resources, Open-File Report DM-49.

^ The Cerrillos Hills Park Coalition, (2000). Cerrillos Hills Historic Park Vision Statement. Public documents: Author. Retrieved August 27, 2007, .

^ McClure R, Schneider A. The General Mining Act of 1872 has left a legacy of riches and ruin. Seattle PI.

^ Boorstin, D.J. (1965). The Americans: The National Experience. New York: Vintage Books, pp. 78-81.

^ Hartmann HL. Introductory Mining Engineering, p. 11. First chapter.

^ http://world-nuclear.org/info/inf27.html

^ http://www.kazatomprom.kz/cgi-bin/index.cgi?p27&version=en

^ Landfill Mining Landfill Mining, Preserving Resources through Integrated Sustainable Management of Waste, Technical Brief from the World Resource Foundation

^ Logging of forests and debris dumping

^ Larmer, Brook (2009-01). "The Real Price of Gold". National Geographic. http://ngm.nationalgeographic.com/2009/01/gold/larmer-text/12. 

^ a b c d e f Moody R. (2007). Rocks and Hard Places. Zed Books.

^ Abrahams D. (2005). Regulations for Corporations: A historical account of TNC regulation, p. 6. UNRISD.

^ Chapin, Mac (2004-10-15). "A Challenge to Conservationists: Can we protect natural habitats without abusing the people who live in them?". World Watch Magazine. 6. http://www.worldwatch.org/node/565. Retrieved 2010-02-18. 

^ a b c US EPA. (1994). Technical Report: Design and Evaluation of Tailings Dams.

^ TE Martin, MP Davies. (2000). Trends in the stewardship of tailings dams.

^ Coumans C. (2002). Mining Problem with Waste. MiningWatch Canada.

^ For an overview of the Bank and mining, see Mining, Sustainability and Risk:World Bank Group Experiences.

^ See the 1995 World Development 23(3) pp. 385-400.

^ GRAMA. (2003). The Challenges of Development, Mining Codes in Africa And Corporate Responsibility. In: International and Comparative Mineral Law and Policy: Trends and Prospects. Summarized in the African Mining Codes Questioned.

^ United States Bureau of Labor http://www.bls.gov/oco/cg/cgs004.htm#nature

^ "Metals Economics Group World Exploration Trends Report". Metals Economics Group Inc.. http://www.metalseconomics.com/pdf/PDAC%202009%20World%20Exploration%20Trends.pdf. Retrieved 2009-05-05. 

^ a b "NIOSH Mining Safety and Health Ventilation". United States National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/mining/topics/topicpage30.htm. Retrieved 2007-10-29. 

^ Kertes, N., (March, 1996). US abandoned mine count still a mystery - General Accounting Office report. American Metal Market, Retrieved August 27, 2007,

^ People, Land, and Water (March, 2007). KEEP OUT! Old Mines Are Dangerous. Office of Surface Mining: U.S. Department of the Interior. Retrieved Aug, 27, 2007,

^ a b c Peterson, J.S.; P.G. Kovalchik, R.J. Matetic (2006). "Sound power level study of a roof bolter" (PDF). Trans Soc Min Metal Explor (320): 1717. http://www.cdc.gov/niosh/mining/pubs/pdfs/splso.pdf. Retrieved 2009-06-16. 

^ Franks, John R., ed. (1996), "Appendix A: OSHA Noise Standard Compliance Checklist", Preventing Occupational Hearing Loss: A Practical Guide, U.S. Department of Health and Human Services, pp. 60, http://origin.cdc.gov/niosh/docs/96-110/pdfs/96-110.pdf 

^ "TauTona, Anglo Gold - Mining Technology". SPG Media Group PLC. 2009-01-01. http://www.mining-technology.com/projects/tautona_goldmine/. Retrieved 2009-03-02. 

^ Naidoo, Brindaveni (2006-12-15). "TauTona to take eepest mine accolade". Creamer Media's Mining Weekly Online. http://www.miningweekly.co.za/article.php?a_id=98516. Retrieved 2007-07-19. 

Further reading

Ali, Saleem H. (2003) Mining, the Environment and Indigenous Development Conflicts. Tucson AZ: University of Arizona Press.

Ali, Saleem H. (2009) Treasures of the Earth: need, greed and a sustainable future. New Haven and London: Yale University Press

Even-Zohar, Chaim (2007) From Mine to Mistress: Corporate Strategies and Government Policies in the International Diamond Industry (ISBN 0953733610)

Geobacter Project: Gold mines may owe their origins to bacteria (in PDF format)

Garrett, Dennis Alaska Placer Mining

Jayanta, Bhattacharya (2003) Principles of Mine Planning. New Delhi: Allied Publishers. 454 pages

Morrison, Tom (1992) Hardrock Gold: a miner's tale. ISBN 0-8061-2442-3

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