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Gold extraction is the extraction of gold from dilute ores using a combination of chemical processes. Gold mining produces about 3600 tons annually, [1] and another 300 tons is produced from recycling. [2] Since the 20th century, gold has been principally extracted in a cyanide process by leaching the ore with cyanide solution.
The ocean reservoir contains an estimated 5.6x10 9 Mg of gold and oceanic gold concentration is about 4 ng Au/L with higher values in some coastal waters. [1] Au(I/III)-ions and Au(0)-colloids are unstable under surface conditions in aqueous solutions and commonly form ligand complexes with substances excreted by microorganisms. [3]
Gold was reported in Maryland as early as 1830, but no production resulted. Placer gold was discovered at Great Falls near Washington, DC in 1861 during the American Civil War by Union soldiers from California. After the war a number of mines were opened on gold-bearing quartz veins in Montgomery County. No gold production has been reported ...
Gold mining is the extraction of gold by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. The expansion of gold mining to ores that are not on the surface has led to more complex extraction processes such as pit mining and gold cyanidation. In the 20th and 21st centuries, most ...
Deep sea mining is the extraction of minerals from the seabed of the deep sea. The main ores of commercial interest are polymetallic nodules, which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain.
Intrusive related gold usually also contains copper, and is often associated with tin and tungsten, and rarely molybdenum, antimony, and uranium. Intrusive-related gold deposits rely on gold existing in the fluids associated with the magma (White, 2001), and the inevitable discharge of these hydrothermal fluids into the wall-rocks (Lowenstern ...
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The economic viability of a deposit will also depend on the grade and tonnage of the reserves of a deposit, along with the costs associated with extracting the ore. Methods of delineating reserves and of extracting gold ore are improving over time, increasing the possibility for production of more gold. [47]