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Chemical Refining of silver bars (5 replies)

Sachin Prakash
8 months ago
Sachin Prakash 8 months ago

What options are there for the chemical refining silver bars with 2-5 % gold?

Dizzy Flores
8 months ago
Dizzy Flores 8 months ago

Electrowinning (or electroplating) at the specific voltage for silver 0.80 volts. If you increase the voltage to 1.52 volts, the gold will plate out. The silver plates out and the gold will be left behind as a sludge in the bottom of the tank.

To minimize the gold loss and not have to clean the tank out to collect the gold, use a very fine mesh cloth bag around the silver bar to collect the gold sludge. Cloth bag and sludge goes into the melting crucible for gold final recovery.

8 months ago
OberstGruppen 8 months ago

I found this very interesting. Thank you for sharing.

Alan Carter
8 months ago
Alan Carter 8 months ago

Ship the Dore to a qualified refinery. The refinery has spent the capital and knows what is required to produce 99.99% Ag bullion. He has described the process used in the refineries.

Carmen Ibanz
8 months ago
Carmen Ibanz 8 months ago

I agree with both of you. However if it is a very small volume and you already possess a gold refining circuit, it may be worth reconsidering from the standpoint of recovering the gold.

Sachin Prakash
8 months ago
Sachin Prakash 8 months ago

Small volume for example:

The precipitated from Merrill Crowe has this values in 75 kg : 0.5% Au, 22% Ag, 20% Pb and 57% Zn after the first foundry the new values in 15 kg are 2% Au, 88% Ag, the rest Pb and Zn (the gold is minimum), so is difficult to recover this few amount, is still electrowinning the best choice or are there more.

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