Copperas or SMB

[yellowfoil]

Hello everybody. I am basically new to refining and my experience is very limited, so I would like to
hear more about how to chose precipitant in given situation. Why is SMB used so extensively and
copperas is not. I watched so many You Tube videos and people never mention why they use SMB
or copperas in given situation, or why they don't like this or that. Thanks in advance for bringing more
light into this questions. I think that it will be of interest to many beginners.

 

[Shark]

SMB is often easier to get and works very well. Copperas is easy for some to get but others have a harder time finding it. Sodium Nitrite works well but can be hard to find and expensive as well. Ascorbic acid can be found and often at a fair price and works really well without a prohibitive cost.

The more common used precipitants are often chosen based on the convenience for the user in one form or another. I keep SMB and copperas because I can get them locally and they compliment each other fairly well. From a dirty solution they tend to drag down contaminants differently so use one for the first refine and the other for the second refine. This leaves some contaminants behind in each drop helping to achieve better purity.

Many report having problems with iron contamination using copperas. While I haven’t noticed it myself, I tend to use copperas for the first drop from dirty solutions where iron is least likely to be problematic. Then for a second refine I use the SMB, which tends leave iron out of the drop.

On fairly clean solutions I use SMB on both drops and still get a very nice piece of gold with minimal issues.

Once you get to commercial levels then things go different ways. But for very many of us SMB is really all we need. But I lean towards using a variety for the small advantages it may provide. I also lean toward quality of the metals more than volumes. I want to produce the best I can, even if it costs me a little more.

 

[Lino1406]

Copperas is more selective for gold, SMB can also precipitate CuCl if in excess and has smell. On the other hand amount vs. gold is 1:1 while copperas 4.5:1

 

[yellowfoil]

Hello friends. Thanks for bringing some light into my question. I Didn't know that sodium nitrite can be used to precipitate gold as well.

I accidently came across copperas by trying to corrode magnetic pins in old battery acid and found crystals of copperas there instead. After recrystallization, I got pretty clean crystal of copperas and found that for each gram of gold, I had to use much higher ratio than 4.5 to 1. Is it because this form of copperas is in some hydrate form and weights more than copperas from the store?

 

[4metals]

Copperas also can go bad. Most of what you can by from an agricultural supply is not the desirable green crystals you want. So
If you got some that had started to oxidize you will not experience the same ratios.

Butcher had posted his method to make it on the forum but I cannot find it.

Big plus, especially for a hobbyist with minimal exhaust, is no stink.

Another benefit to copperas is it will not effect any Platinum or Palladium in solution. So if you are dissolving dental for example drop the gold with copperas and the Palladium and any Platinum will come down easier.