How Is Gold Processed Into Rings?
Gold ore is just a rock. Before a goldsmith can turn the gold into a ring, someone has to extract the gold from the ore---or from scrap metal---with various chemical processes. Once the gold is purified, it will be mixed with other metals to create an alloy strong enough to wear on our fingers.
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Cyanidation Process
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Cyanide solution is one of the few liquids that will dissolve gold. When the cyanide solution washes over ore in the presence of oxygen, gold dissolves into the solution, according to Mining Basics, and can be separated from the cyanide later. Fortunately for the workers, weak cyanide solutions work better than stronger, more toxic ones.
Miller Process
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Molten gold doesn't react as strongly to chlorine gas as the impurities in the gold do, according to Gold and Silver Mines. The Miller process involves melting the gold, then blowing chlorine into the molten mix. The impurities combine with the chlorine and the resulting compounds separate into a layer on the surface, leaving the gold underneath 99.5 percent pure.
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Wohlwill Process
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In the Wohlwill process, metallurgists place impure gold in a solution of hydrochloric acid and gold chloride, which they then electrify. The current dissolves the gold mix, separating the impurities out and collecting the gold at a negative electrode in the vat. The result generates 99.99 percent purity.
Cupellation
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Treated lead can absorb metals out of impure scrap, Assaying.org says. In the cupelling process, an assayer pours slag containing gold into a lead cup, which then absorbs the metal. The assayer places lead into cupel---a container typically made of magnesium oxide---and heats it to around 1,700 degrees F. At that temperature, the cupel absorbs the lead, leaving a ball of gold behind.
Alloying
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Having purified the gold, the next process involves melting the gold and alloying it with other metals. Pure 24-karat gold is too soft to handle easily, but combining it with silver, copper or other metals gives it more hardness. According to Gold and Silver Mines, white gold is more than 70 percent silver. Metalsmiths can cut and shape the gold alloy into rings.
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References
Resources
- Photo Credit gold ring in hand image by Matt Self from Fotolia.com
