Ageo308 said:
Thanks Harold, although i must admit when my jeweller friend tried this process, he did burn in the kiln as stated then melted straight away and the piece actually turned into a real hard piece of glass.
Of course it did. For all practical purposes, he melted with the idea that the values would magically appear as a solid piece. It doesn't work like that. Melting that material without a collector, and a thinning agent for the silica, which should be left behind but dissolved with soda ash, is a mistake. Much of the material won't dissolve, so there must be a thin flux to absorb the non-metallics and allow the metallics to collect and settle. Your friend is now stuck with something that will require either processing by ball mill, or it must be broken very fine, properly fluxed, and run with a collector. Had he stayed away from the furnace, that would not be the case.
Mind you, I have no quarrel with anyone that chooses to process polishing wastes by furnace----I'm simply stating that the process presented isn't a good one. It works, but the losses are likely to exceed what should be considered acceptable. That, of course, depends on what was used as a flux, but the indication is this person didn't have a clue.
So he's trying this method today to actually see if any of this rings true.
This method? Not sure of your meaning, but if you're implying the one I recommended, it never failed me. I processed polishing wastes on an ongoing basis, for more than 20 years.
Im assuming the cheapest method is the chemical way yes?
I'd prefer to have you think of it as a functional way for those that don't have at their disposal a great reducing furnace to process such wastes, yet a need to achieve a decent recovery. The problem with melting, even after the removal of considerable sand, is that it's very hard to collect the miniscule bits of values. Unless the flux is very fluid, and a collector of sorts is used to agglomerate the often colloidal sized particles, much of it is lost in the slag, some identifiable as prills, with the rest so fine it isn't recognizable. Have your friend pay for a fire assay of his piece of glass so he'll understand how poor was the advice he followed.
I do not recommend the home refiner attempt to melt such material, and if the decision to do so is made, the last thing that should be done is to remove the silica as recommended. If you'll study a good fluxing recipe, you'll come to understand that silica is a very important component. The one I used included the
addition of silica, so I see no reason to eliminate what is a necessity.
By the way, my flux was assayed after the recovery of values and was so low in content that it was not acceptable at a refinery that specialized in recovering values from low grade wastes. The formula I developed worked very well, but it was very aggressive in that it would dissolve crucibles and furnace lining in short order. That was the chief reason I got such good extraction. In my case, the damage created was more than offset by a virtually complete recovery. I relied on silver chloride to act as my collector-----which turned out to work exceedingly well, at least from all indications.
Harold
