Ask A Scientist General Science Archive

name         Meka
status       other
age          30s

Question -   How is gold purified?  What happens when it is in the fire?  So the impurities 
go the top to be skimmed off?  Pleases explain the process.
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Mika,

To extract gold from pyrite compounds, they are sometimes treated in a proprietary chlorine 
process.  The roasted pyrites are moistened with water and impregnated with chlorine gas.  
Gold chloride is then leached out with water, and the gold is precipitated by reduction with 
ferrous sulfate or solid charcoal.  Bromine water is sometimes used instead of chlorine.

The gold obtained is then processed into bullion.  The gold bullion is then refined.  If the 
gold contains copper, it is removed by oxidizing it with borax and nitric acid.  I hope this 
gives you an acceptable answer to your question.

Sincerely,

Bob Trach
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