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Although both have industrial uses, they are better known for their uses in art, jewelry, and coinage. Other precious metals include the platinum group metals: ruthenium , rhodium , palladium , osmium , iridium , and platinum , of which platinum is the most widely traded. [ 1 ]
The expansion of gold mining in the Rand of South Africa began to slow down in the 1880s, as the new deposits being found tended to be pyritic ore. The gold was difficult to extract from such ores. A process known as chlorination was once used to treat pyritic gold ore. Typically, the ore was roasted and then treated with chlorine gas. The ...
The Wohlwill process is an industrial-scale chemical procedure used to refine gold to the highest degree of purity (99.999%). [1] The process was invented in 1874 by Emil Wohlwill. This electrochemical process involves using a cast gold ingot, often called a doré bar, of 95%+ gold to serve as an anode.
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 ...
Gold, a chemical element; Genomes OnLine Database; Global-scale Observations of the Limb and Disk, a NASA Explorer Mission of Opportunity; GOLD (parser), an open-source parser-generator of BNF-based grammars; Graduates of the Last Decade, an Institute of Electrical and Electronics Engineers program to garner more university level student members
Silver was removed by filtering and gold was then recovered by evaporating the liquid and heating the residue. Nitric acid was suitable for separating small quantities of gold from silver and aqua regia used to separate small quantities of silver from gold. Aqua regia acid process is used by refiners of scrap gold used in jewelry manufacturing.
In the past, heterogeneous gold catalysts have found preliminary commercial applications for the industrial production of vinyl chloride (precursor to polyvinyl chloride or PVC) and methyl methacrylate. [4] Traditionally, PVC production uses mercury catalysts and leads to serious environmental concerns.
Cyanide can be safely used in the gold mining industry. [3] A key feature for safe use of cyanide is to ensure adequate pH control at an alkaline pH level above 10.5. At industrial scale, pH control is mainly achieved using lime, as an important enabling reagent in gold processing. [4]