Getting started refining jeweler bench sweeps

[Stonecutter1]

It was mentioned earlier about inquarting the more course material. My question is dont you have to know approx what karat the material is to start with. Everything I have read says to alloy down to about 6KT. What do you do when you have a mix of various metals and karats to process?

 

[4metals]

One thing about inquarting that is nice is that it is quite forgiving if you add too much silver, trouble comes from too little silver. What inquarting does is space out the molecules of the metals that are insoluble in nitric so the nitric can penetrate and dissolve all of the nitric soluble metals. So too much is never an issue, you just space out those molecules a little more. Just make sure you melt everything together, mix it well and pour it into water so it makes smaller pieces with more surface area. This will make the reaction progress faster.

Assume all of the non magnetic metal in the oversized material is the highest karat you work with and add silver accordingly. Then you cannot miss.

 

[Stonecutter1]

Awesome, thank you. That helps alot. Next question, on the acid bath. I am to use diluted nitric, is this correct? Say 50- 50 nitric and distilled water? Is this the same ratio when processing my sweeps and the inquarted material which I will be doing separately of course.

 

[4metals]

If you are using nitric on your sweeps it is just to recover any silver. I would cut the nitric to water ratio to 1 part nitric 3 parts distilled water for leaching sweeps because there is a low percentage of silver to begin with and the silver present is finely divided so it will dissolve easily.

I have found that processing sweeps also benefits from an HCl treatment. In order to facilitate this, any sweeps first leached with nitric need to be roasted again after the nitric leach to assure all traces of nitric are gone before the HCl treatment or you will dissolve some gold.

 

[Stonecutter1]

When you say to roast the sweeps again do you mean just put them back in the pan and sort of re- incinerate for a short time? When leaching my sweeps in the nitric bath do I just wait for the reaction to die down and fumes to dissapate to know that the process is finished?

 

[4metals]

Yes, just re incinerate however you did it the first time. And when the reaction stops blowing red fumes the metals that will react, have reacted. In rare circumstances all of the nitric is consumed but with sweeps, it's rare.