Non-Chemical Other neutralisation techniques

[Noxx]

Hello guys,
Just wondering:
We already know that we can neutralize the excess nitric in AR using Urea (for NOx) or evaporation. But could we use another base metal to use up the remaining nitric ? Not copper because it will make precipitate things, but maybe iron ? or nickel ? This could only be used for first precipitation because I suppose it adds some contaminants. Maybe it does not worth it at all... I was just questioning myself...

 

[Harold_V]

I fail to see any advantage in that you would include contamination that you're trying to eliminate. It would be much like dissolving everything in AR instead of attempting to eliminate base metals before dissolving values. The use of most metals would precipitate not only the values, but some of the base metals as well. Iron, for example, would do just that. It's counter productive and should be used only as a recovery technique when things have gone wrong with your processing.

As you may have already learned, I am not a fan of dissolving gold in AR for recovery purposes, aside from special occasions. That would include gold that is on substrates that are not metallic, and may be otherwise difficult or impossible to recover by other methods.

The only other time I suggest the use of AR for dissolving values from other metals would be when you take advantage of the base metal's ability to precipitate the values. By that process, you use less AR than would be required to dissolve everything, than allow the remaining base metal to precipitate the values, thus consuming more of the base metals. When all the values are down, the base metal solution is decanted, eliminating the vast majority of the unwanted metal that becomes the contaminant in pure gold. The final dissolution will contain a reduced amount of the base metals, improving the overall quality of the recovered gold.

As you alluded, it is best to NOT use any metal to precipitate your values. The closest you'd come to that would be in the use of ferrous sulfate, which is relatively easy to eliminate from the values via a careful washing regimen.

Harold

 

[Noxx]

Thanks Harold.

I'm currently buying some distillation apparatus to make my own nitric acid (salts free).

This way I'll be able to dissolve inquarted gold efficiently.

 

[Harold_V]

Thanks Harold.

I'm currently buying some distillation apparatus to make my own nitric acid (salts free).

Way cool! Be sure to tell us how it goes when you get set up!

It's a damned shame we have to resort to such tactics.

There are times when I wonder if your (and our) government is using good sense. We have given up so much in the name of national security.

Harold

 

[Lino1406]

With dilute HNO3 - does nothing.
With conc. HNO3 - forms an explosive