Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Remove tin from gold (1 reply)

2 months ago
Markhb 2 months ago

Hello. I have approx 20oz of gold that I have inquarted with copper and digested with nitric acid, 2/3 water, 1/3 nitric. I have washed, dried and analyzed it using an Olympus XRF.My problem is the presence of tin which I have read cannot be removed by nitric. I have previously done the same inquartation procedure on a smaller amount of scrap jewellery gold, which worked well and gave me an xrf reading of 100% gold + or - .5%, it did not contain tin. I understand that I may be able to use hcl to remove the tin? Any advice or opinion on this would be most welcome and also tips for washing the gold after the acid digestion, i.e wash with hot or cold water, distilled or not, I understand chlorine can cause an issue. How long should I let the acid do its thing? etc. Please pardon my inexperience

4 weeks ago
Jorge 4 weeks ago

When a silver ore contents much tin, zinc, or lime is present in the ore, the borax should be increased in quantity, approximately 15 to 20% the weight of ore.

In the case of gold scrap, if lead or tin got into the gold, the gold bar would be unworkable and exceedingly brittle. To avoid the problem and separate the tin, the addition of bichloride of mercury is the best flux to use.

Sometime, beads are mixed with 15 to 25 cm3 of hydrochloric acid, and heat to boiling. After heating, allow to stand for fifteen minutes, dilute with cold distilled water, and filter.

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