Non-Chemical can a person use too much sulphur dioxide gas

[golddie]

sulphur dioxide gas on page 57 of Hokes book
to throw down the gold can a person use too much sulphur dioxide gas

 

[lazersteve]

Too much SO2 (or solid SMB) can convert dissolved copper II chloride to insoluble copper I chloride in non-acidic dilute solutions.

Steve

 

[Noxx]

Well, you would have to use very large amounts of it. Simple answer is no.

 

[4metals]

I hate to disagree but it is easy to over gas with SO2, I've seen it many times when a job is close to the end point and the operator goes for coffee and comes back to an overgassed solution. The copper chloride crystals appear as white crystals in the yellow gold. Theoretically the copper can be leached in concentrated HCl but in practice its best to re-digest in Aqua regia and gas it again. Without a coffee break.

 

[Harold_V]

I hate to disagree but it is easy to over gas with SO2, I've seen it many times when a job is close to the end point and the operator goes for coffee and comes back to an overgassed solution. The copper chloride crystals appear as white crystals in the yellow gold. Theoretically the copper can be leached in concentrated HCl but in practice its best to re-digest in Aqua regia and gas it again. Without a coffee break.

That's one hell of an argument for not processing values with base metals.

Harold

 

[Oz]

However Harold’s recommended HCl washes of gold precipitates until clear of color will fix the mistake.

 

[4metals]

As Harold has stated the HCl wash will clean things up if copper drops out. However if you are dropping any quantity of gold, the HCl wash cannot be done in the filter as the acid tends to channel through the gold leaving some areas untouched. I've seen this tried by refiners who discover the white crystals in their sponge sitting in the filter funnel and just add HCl to dissolve it, never removing it from the funnel. To be effective it has to be either tumbled or well mixed in the acid to assure complete dissolution.

I've also seen guys over gas, melt and pour into shot and treat the pinkish colored shot with HCl to clean it up. That is only a cosmetic fix and the gold still has copper in it.

I think everyone looking to produce fine gold should print Harold's fine shot picture and have it hanging by the scale for a reference.