Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Parting of precious metals - lead alloy instead of cupellation (2 replies and 1 comment)

A
Ahmed Zaky
7 years ago
Ahmed Zaky 7 years ago

I have ( gold - lead - silver)  and i ask if it is suitable to make parting for alloy to separate gold from lead and silver by nitric acid instead of cupellation by using bone ash

      Thank you

.999
7 years ago
.999 7 years ago
Like
1 like by David

Yes. After you dissolve the silver and lead away you can separate the silver from the lead while it's in nitrate form by adding a chloride ion. Common nacl salt will serve the purpose. The silver will then be dropped as a chloride which can be converted to elemental silver rather easy. The lead and other metals that is left over in solution can then be neutralized using magnesium hydroxide and disposed of properly.

A
Ahmed Zaky
7 years ago
Ahmed Zaky 7 years ago
Like

thanks for reply, but i just ask if it is correct that i can dissolve lead alloy after fire assay directly in nitric acid without cupellation

.999
7 years ago

Yes! Lead will dissolve fairly readily in hot weak nitric - 7 parts distilled water and 1 part concentrated nitric acid ( 67-69% ). You can't use strong nitric because lead nitrate crystals will form on the surface and block the dissolving action. Lead nitrate is not very soluble in strong nitric. The distilled water will prevent your having to screw around with any lead chloride that might otherwise be formed. For the same reason, I would also rinse the gold well with hot distilled water.

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