Prevent copper begin attack in cyanide solution
- Thread starter Franciz
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A great deal depends on what you are processing. In ores, copper is not dissolved simply by keeping the free cyanide levels very low---about .02%, if memory serves. Please correct me if I'm wrong.Franciz said:
Harold
You will attack the copper, somewhat, when using m-NBSS and cyanide and there's not much you can do about it. Just try to minimize it. For example, don't let the parts dwell in the solution after the stripping is finished. That solution will dissolve the nickel barrier plating and expose the copper, if given enough time. So, try to get the parts in and out quickly. Are you heating the solution?
Agitation of the parts will speed things up and it can reduce the copper attack. A common way is to put the parts in a plastic mesh basket and bob it up and down in the solution until stripping is complete. You can run a few batches of parts in the same solution before zincing.
In the patent literature, there are things you can add to this solution to prevent attack on the copper. However, these additions make recovery of the gold from the solution very difficult (zincing or electrolytic recovery will no longer work well) and somewhat dangerous.
Agitation of the parts will speed things up and it can reduce the copper attack. A common way is to put the parts in a plastic mesh basket and bob it up and down in the solution until stripping is complete. You can run a few batches of parts in the same solution before zincing.
In the patent literature, there are things you can add to this solution to prevent attack on the copper. However, these additions make recovery of the gold from the solution very difficult (zincing or electrolytic recovery will no longer work well) and somewhat dangerous.
