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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“Most events recorded in history are more remarkable than important, like eclipses of the sun and moon, by which all are attracted, but whose effects no one takes the trouble to calculate.”
—Henry David Thoreau (1817–1862)
“There has never been in history another such culture as the Western civilization M a culture which has practiced the belief that the physical and social environment of man is subject to rational manipulation and that history is subject to the will and action of man; whereas central to the traditional cultures of the rivals of Western civilization, those of Africa and Asia, is a belief that it is environment that dominates man.”
—Ishmael Reed (b. 1938)
“I believe that history might be, and ought to be, taught in a new fashion so as to make the meaning of it as a process of evolution intelligible to the young.”
—Thomas Henry Huxley (1825–95)