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Gold/Mining/Energy : Gold Price Monitor -- Ignore unavailable to you. Want to Upgrade?

To: long-gone who wrote (81028)	1/23/2002 5:56:02 PM
From: E. Charters	Respond to of 116763

Copper is common in some mines, and zinc. These both may be controlled for in slagging gold in refinery, sometimes by attacking the cyanide precipitate-concentrate by acid before hand. Gold is soluble in copper oxide, so to form a copper oxide slag is verboten for good recovery in the furnace room. It is tough, though, to make copper oxide slag. You can prevent that, though with care as Noranda did in recovery its gold from flotation concentrate by cyanide. Usually copper is passed through into the bullion. Some bullion may go to 60% copper. Copper and zinc were removed from two Timmins mines' gold precipitate from the cyanide solution by either sulphuric or sulphuric and hydrochloric. Nickel-copper is rare. It does occur and the precipitate may be pretreated by nitric acid so that the slag does not form speiss. Speiss a smelter or furnace product that dissolves gold into it and reduces recovery. ---> The reason this treatment is done is that the cyanide process picks up other metals in the leaching in plant on the ore. The gold itself of the vein may not contain that much of the other metals controlled for by these processes, which in the concentrate may include alumina, iron, lead, arsenic, copper, selenium, tellurium, and zinc. Zinc, iron, alumina and lead are usually slagged off into oxides in the furnace. If the Croesus mine nugget contains crystals of gold it is exceedingly rare as gold does not easily form a crystal. (cubic if it does) This may mean that its gold is in fact fairly pure. It is significant that in the assaying of gold the control of the metals such as copper are all done by oxidization and copper does not enter into the equation as a deleterious metal in making a slag, even in copper ores. EC<:-}