Gold from base metals

Flotation of Gold From Base Metal Sulphide Ores... 

FLOTATION OF GOLD FROM BASE METAL SULPHIDE ORES... 

Arsenic in the elemental form is a brittle, grayish crystal that becomes darker when exposed to air. It is seldom found in the pure elemental form but rather in minerals (compounds). It has a long history of use as a poison, and many alchemists were poisoned when using it in their attempts to produce gold from base metals. 

The alchemists never succeeded in making gold from base metals, yet their experiments, recorded under a mystical and intentionally obscure terminology, gradually revealed metallic arsenic and antimony. Bismuth was discovered by practical miners. Finally, in the latter part of the seventeenth century, the pale light of phosphorus began to illumine the dark secrets of alchemy and to disclose the steady advance of scientific chemistry. 

The teachings of Aristotle and events in Egypt, India, China, and Mesopotamia stimulated the practice of alchemy. The early roots of alchemy, which was practiced for nearly two thousand years, are difficult to trace because much of the practice was shrouded in mystery and transmitted by oral tradition. The two main goals of the alchemists were to produce gold from base metals and to develop potions that would confer health and even immortality. The alchemists were crafts people who combined serious experimentation with astrology, incantations, and magic in hopes of finding the philosopher s stone. 

Alchemy The study and manipulation of matter based on a belief that matter can be transformed from one form to another by physical, spiritual or magical processes, or a combination of such processes. Although alchemical ideas extend back to at least 5000 b.c.e and existed in all civilizations, there was a great expansion of alchemical activities between 800 and 1600 c.E. after which time alchemical ideas were gradual replaced with empirical concepts of matter. Alchemy was often directed toward the making of gold from base metals or the creation of an elixir of life that gave immortality. 

Above the obvious goal of alchemy and the best-remembered one was the production of gold from base metal. Here in a 19th-century engraving, executed long after alchemy had lost its preeminent position as a respectable science, an alchemist displays a small nugget of gold to his patron. 

Sheet nd Sha.pe Waxes. Sheet and shape waxes are used to produce patterns from which complete or partial dentures are cast of gold or base metal alloys. They are used to fabricate the restoration prototype directly upon a refractory investment cast. 

In the case of a copper-zinc and copper-lead-zinc ore, gold collects in the copper concentrate. During the treatment of lead-zinc ores, the gold tends to report to the lead concentrate. Information regarding gold recovery from base metal ores is sparse. 

The flotation of elemental gold, electrum and tellurides is usually very efficient, except when these minerals are floated from base metal, massive sulphides. 

Bulatovic, S.M., An Investigation of Gold Flotation from Base Metal Lead-Zinc and Copper-Zinc Ores, Interim Report LR049, 1996. 

Ambivalence, as we use this term in everyday speech, has no place in modern science. Even premodern science seems troubled by ambivalence. For if gold can be transmuted from base metals, this must mean that it can be transmuted back into base metals. The Renaissance philosopher-critic Benedetto Varchi cites Aristotle on the generation of species as an argument against the truth of alchemy " ... 

Silver is widely distributed throughout the world. It rarely occurs in native form, but is found in ore bodies as silver chloride, or more frequently, as simple and complex sulfides. In former years, simple silver and gold-silver ores were processed by amalgamation or cyanidation processes, The availability of ores amenable to treatment by these means has declined. Most silver is now obtained as a byproduct or coproduct from base metal ores, particularly those of copper, lead, and zinc. Although these ores are different in mineral complexity and grade, processing is similar. 

Anon., Gold from Russia s Muruntau Deposit , Comolidated Gold Fields Report Coal, Gold and Base Metals, 1978,... 

In the tenth chapter of this work, he explained how precious metals were separated from base metals and from one another. The techniques that he discussed often involved the use of acids, as in the separation of silver from gold. They also involved furnaces. 

Sonawane, J.V., Pabby, A.K., and Sastre, A.M., Pseudo-emulsion based hollow fiber strip dispersion (PEHFSD) technique A novel methodology for gold recovery from base metals in cyanide media, AIChE J., 54, 453, 2008. 

Fig. 6.5. Temperature dependence of the catalytic activity of supported gold and base metal oxide catalysts in the WGS. Starting reaction gas mixture was 4.88 vol% carbon monoxide in argon water vapour partial pressure 223 Torr SV 4,000 h 1 atm. Au/a-Fe203 (Q) CuO/ZnO/AhOa ( ) a-Fe203 ( ) AU/AI2O3 ( ). Rates are expressed in mol m h x 10 (adapted from [219])...

Zhukhhstov AP, Dragrrlescu EM, Rtrsinov VL, Kovalenker VA, Zvyagin BB, Kirz mina OV (1996) Sericite with a non-cerrtrosynunetric stractiue from the gold-silver base metal deposit BanskaStiavrrika (Slovakia). Zap Vseross Min Obshch (Proc Russian Mineral Soc) 125 47-54 (in Russian)... 

Alchemists thought that heating base metals with sulfur caused the freeing of gold from a metal. They thought that when they got the golden color, they... 

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