Yahoo奇摩 網頁搜尋

  1. 約 116,000,000 項搜尋結果

  1. A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold.The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from the late 1920s to 1932 as well as from 1944 until 1971 when the United States unilaterally terminated convertibility of the US dollar to gold, effectively ending ...

  2. en.wikipedia.org › wiki › GoldGold - Wikipedia

    Gold is the most malleable of all metals. It can be drawn into a wire of single-atom width, and then stretched considerably before it breaks. [11] Such nanowires distort via formation, reorientation and migration of dislocations and crystal twins without noticeable hardening. [12] ...

    • metallic yellow
    • group 11
    • 79
  3. en.wikipedia.org › wiki › Gold_miningGold mining - Wikipedia

    • History
    • Statistics
    • Methods
    • Gold Ore Processing
    • Business
    • Adverse Effects and Responses
    • Safety
    • Further Reading

    The exact date that humans first began to mine gold is unknown, but some of the oldest known gold artifacts were found in the Varna Necropolis in Bulgaria. The graves of the necropolis were built between 4700 and 4200 BC, indicating that gold mining could be at least 7000 years old. A group of German and Georgian archaeologists claims the Sakdrisi ...

    Despite its decreasing content in ores, gold production is increasing. This increase can be achieved through ever larger-scale industrial installations as well as innovations, especially in hydrometallurgy.

    Hard rock mining

    Hard rock gold mining extracts gold encased in rock, rather than fragments in loose sediment, and produces most of the world's gold. Sometimes open-pit mining is used, such as at the Fort Knox Mine in central Alaska. Barrick Gold Corporation has one of the largest open-pit gold mines in North America located on its Goldstrike mine property in north eastern Nevada. Other gold mines use underground mining, where the ore is extracted through tunnels or shafts. South Africa has the world's deepes...

    By-product gold mining

    Gold is also produced by mining in which it is not the principal product. Large copper mines, such as the Bingham Canyon mine in Utah, often recover considerable amounts of gold and other metals along with copper. Some sand and gravel pits, such as those around Denver, Colorado, may recover small amounts of gold in their wash operations. The largest producing gold mine in the world, the Grasberg minein Papua, Indonesia, is primarily a copper mine. A modest amount of precious metal is a by-pro...

    Cyanide process

    Cyanide extraction of gold is the dominant method for obtaining gold. Finely ground rock is treated with a solution of sodium cyanide. The extract is absorbed onto carbon. The gold can be removed from the carbon by using a strong solution of caustic soda and cyanide. Gold cyanide is then converted to relatively pure gold by a variety of methods. The technique using dissolution with alkaline cyanide has been highly developed over recent years. It is particularly appropriate for low grade gold...

    Mercury process

    Historically, mercury was used extensively in placer gold mining in order to form mercury-gold amalgamwith smaller gold particles, and thereby increase the gold recovery rates. Large-scale use of mercury stopped in the 1960s. However, mercury is still used in artisanal and small-scale gold mining (ASGM), often clandestine, gold prospecting.

    Small operations

    While most of the gold is produced by major corporations, millions of people work independently in smaller, artisan operations, in some cases illegally. Artisanal mining refers to workers who use rudimentary methods to extract and process minerals and metals. Socially and economically marginalized communities mine to escape extreme poverty, unemployment and landlessness. In Ghana, the galamseys are estimated to number 20,000 to 50,000. In neighboring francophone countries, such workers are ca...

    Gold mining can significantly alter the natural environment. For example, gold mining activities in tropical forests are increasingly causing deforestation along rivers and in remote areas rich in biodiversity.Other gold mining impacts, particularly in aquatic systems with residual cyanide or mercury (used in the recovery of gold from ore), can be ...

    Noise

    Within the United States, the Mine Safety and Health Administration (MSHA) has set noise exposure limits for those within the mining industry. These noise exposure guidelines state that the "Permissible Exposure Level" (PEL) of noise is 90 dBA as an 8-hour time-weighted-average. Mine workers exposed to a time-weighted average of at least 85 dBA fall into the "Action Level" in which workers with exposures exceeding that level are placed into a hearing conservation program. The National Institu...

    Ali, Saleem H. (2006), "Gold Mining and the Golden Rule: A Challenge for Developed and Developing Countries", Journal of Cleaner Production, 14 (3–4): 455–462, doi:10.1016/j.jclepro.2004.05.009
    Gudde, Erwin G. California Gold Camps: A Geographical and Historical Dictionary of Camps, Towns, and Localities Where Gold Was Found and Mined; Wayside Stations and Trading Centers(Univ of Californ...
    Hess, Frank L., C. W. Hayes, and W. Lindgren. "Gold mining in the Randsburg quadrangle, California." Contributions to Economic Geology: US Geological Survey Bulletin (1910): 23–47. Online
    Kelley, Robert L. "Forgotten Giant: The Hydraulic Gold Mining Industry In California." Pacific Historical Review 23.4 (1954): 343–356. Online
    • Venezuela
    • Netherlands
    • Germany
    • Belgium
    • Switzerland
    • Austria
    • India
    • Mexico
    • Bangladesh
    • See Also

    Before 2012, the Central Bank of Venezuela, Banco Central de Venezuela (BCV), held about 211 tons of its 365 tons of gold reserves in American, European, and Canadian banks. In January 2012, however, Venezuela completed the move of 160 tons of gold bars (valued at about $9 billion) back home. The operation was ordered by President Hugo Chávez in Au...

    In 2014, 122.5 tons of Dutch gold reserves were returned to Amsterdam from New York, where they had been stored in a vault of the Federal Reserve Bank of New York; the De Nederlandsche Bank, the Dutch central bank, said that it "felt that in times of financial crisis, it was better to have the gold near at hand." The Netherlands continues to store ...

    In January 2013, Deutsche Bundesbank, the German central bank, announced plans to repatriate 300 tons of its 1,500 tonne reserve from the U.S., and 374 tons from France by 2020, in order to store (1,695.3 tons) of its official gold reserves in Frankfurt. The gold stored in the U.S. was acquired by West Germany during a period of trade surpluses wit...

    In an interview with Belgium broadcaster VTM Nieuws, Luc Coene, governor of Belgium’s central bank, confirmed that the bank is looking at how they can bring their gold reserves back into the country.[citation needed] According to IMF data compiled by the World Gold Council, Belgium holds 227.4 metric tons of gold, representing 34.2% of its official...

    Save our Swiss Gold motion was a citizen movement that called for the central bank to hold at least 20 percent of its assets in gold, prohibit selling any gold in future and bring all its reserve of gold back in the country. This referendum was held on November 30, 2014, but was lost.[citation needed]

    Austria currently holds 80% of their 280 tons of gold in London, 17% in Austria, and 3% in Switzerland. Citing a need for risk diversification, Austria announced they will be repatriating gold from London during 2015. After the repatriation process has completed, 50% of Austria's gold will be held in Austria, 20% in Switzerland, and the remaining 3...

    India's central bank bought 200 metric tons of gold from the International Monetary Fundin 2009, in the first major move by a major central bank to diversify its foreign-exchange reserves.

    In 2011, Mexico quietly purchased nearly 100 tons of gold bullion, as central banks embarked on their biggest bullion buying spree in 40 years. China, Russia, and India had acquired large amounts of gold in recent years, while Thailand, Sri Lanka and Bolivia had made smaller purchases.

    On September 9, 2010, the International Monetary Fund (IMF) announced the sale of 10 metric tons of gold to the Bangladesh Bank, the central bank of Bangladesh.

  4. en.wikipedia.org › wiki › E-golde-gold - Wikipedia

    • Beginnings
    • Criminal Abuse
    • Prosecution and Closure
    • See Also

    e-gold was founded by oncologist Douglas Jackson and attorney Barry Downey in 1996. The pair originally backed the services accounts with gold coins stored in a bank safe deposit box in Melbourne, Florida. By 1998, G&SR (the system operator) was an Affiliate Member of NACHAand a Full Member of NACHA's The Internet Council. The company was launched ...

    e-gold was a target of financial malware and phishingscams by criminal syndicates and was used for illegal activities.

    In 2007, a U.S. federal grand jury indicted e-gold, accusing it of serving identity thieves and child pornographers. The company denied the charges. In July 2008, the company and its three directors entered into a plea agreement. Jackson pleaded guilty to operation of an unlicensed money transmitting business and conspiracy to engage in money laund...

  5. en.wikipedia.org › wiki › GoldcorpGoldcorp - Wikipedia

    goldcorp .com. Goldcorp Inc. was a gold production company headquartered in Vancouver, British Columbia, Canada. The company employed about 15,800 people worldwide, [4] engaged in gold mining and related activities including exploration, extraction, processing and reclamation. Goldcorp’s operating assets included four mines in Canada, two ...

  6. AngloGold Ashanti Limited is a global gold mining company. It was formed in 2004 by the merger of AngloGold and the Ashanti Goldfields Corporation.It is now a global gold producer with 21 operations on four continents. The company is listed on the New York, Johannesburg, Accra, London and Australian stock exchanges, as well as the Paris and Brussels bourses.

  1. 其他人也搜尋了