Removing Diamonds from borax/flux/slag

[Fournines]

Sorry if I'm asking this question in the wrong section, but I wanted to know if anyone knows of a way to do this.

After karat scrap jewelry is melted, poured, the bar cools, and the slag solidifies, does anyone know of a way to reclaim diamonds and other stones that might be locked up inside the slag?

 

[Oz]

If your slag is just borax, a boil in 10% sulfuric acid will soften and remove it. By your description though it seems you may have a more complicated slag than just some flux from melting up a button of gold in a borax fluxed dish.

 

[Fournines]

A little more complicated. I have clients who melt 700 oz of scrap in a crucible and has a over half a pound of slag come off the bar.

It is usually only borax added to the melt. Maybe I'll test out boiling some in sulfuric and see what happens.

 

[Oz]

Why are they melting 700 ounces of gold scrap into one lump? That surely makes any further processing far more difficult.

 

[Fournines]

It's standard procedure for buying on a melt/assay basis.

Client's material is melted, liquid pin sample taken, molten material is poured into a mold. The bar is then put into holding until the assay is completed and the lot is settled with the customer.

When actual refining is to begin, many of those large bars are re-melted together to kick off the process.

 

[Oz]

In that instance it makes sense instead of the labor checking each piece of jewelry as long as they are sure stones stay in the flux. Since you have access to the flux you may wish to process it for values other than stones.

 

[Irons]

Diamond will graphitize at temperatures over 800 Deg. C in the presence of Oxygen.

I would hate to see a valuable stone damaged by such treatment.