I been trying g to learn more about refining with borax. Haven't been able to find a good video on it.
If you have refined with it. Looks like you sprinkle a bit on top of the slag layer. But shouldn't use to much. Is there like a weight ratio. Any info about borax would help.
Borax can be used in a couple of ways;
1. Sprinkle some in with placer Au, which usually has some minor black sand and/or silica, or other heavy minerals. Quantity will vary depending on the amount of impurities. More is added with higher quantities of impurities. Borax will act as a common collector for the non alloyable components ( minerals other then Gold/Silver ) of the melt. There is no ratio that can be given, as placer cons will vary from clean up to clean up. Trying to smelt a lot of black sand, with very little Au ( Gold ), generally results in a glassy mess, with poor or no recovery. I would say a 25% Au to 75% black sand ratio would be the very bottom of the scale I would use Anhydrous Borax only, as the flux/mineral collector.
2. Borax, in combination with other chemistry, such as Sodium Hydroxide/carbonate, Litharge ( Lead Oxide ), Silica, Carbon compounds, Fluorspar, and a host of other combinations, to balance the acidic or basic components in whatever you are trying to smelt. To understand more of what I am talking about, read up on assaying or smelting in the library section of this forum.
If you want some quick, but relatively inaccurate videos on smelting ores, watch some videos put out by Mount Baker Mining and Metals on Youtube. He explains the process accurately, with the exception of the do's, dont's, and why's, of accurate chemistry.
Sreetips, on Youtube, frequently melts some dirty Gold ( jewelers sweeps ), which he occasionally adds some Anhydrous Borax to, for collecting the crud.
To answer your other question about sprinkling it on the slag, no- it is the slag. You might add it to the other chemicals in the slag, if you used other components, to again adjust the PH of your melt, for better viscosity ( ability to pour out of the crucible ).
The term refining, as referred to in refiners language, is to improve the metal content towards its ultimate elemental purity.
Using fluxes only separates the precious metals from the other less worthy mineral components. It really doesn't "refine" PMs to increase the purity of the metal. Certain flux mixtures will, but for now, I am trying to give the basics on how and when to use Borax only.
