History
According to de Lecerda and Salomons (1997) mercury was first in use for extraction at about 1000 BC., according to Meech and others (1998), mercury was used in obtaining gold until the latter period of the first millennia. A technique known to Pliny the Elder was extraction by way of crushing, washing, and then applying heat, with the resultant material powdered.
The solubility of gold in a water and cyanide solution was known by 1783 (Scheele), by Bagration in 1843 and Elsner in 1846 who recognized the necessity of oxygen in the process, (a method of exctraction by chlorination (Plattner) considered during 1848 proved uneconomical) this prior to the discovery of an economical method of treatment with potassium cyanide by J.S. MacArthur (with R. and, or, W. Forrest). Development of understanding from 1887 led to the discovery dated to 1888 (and elsewhere 1890) that is known as the MacArthur-Forrest process.
The method heap leaching was first proposed during 1969 by the United States of Americas' Bureau of Mines, in use by the 1970s.
Read more about this topic: Gold Extraction
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