goldsilverpro said:The easiest and, probably, most accurate way on identical parts (at least, in appearance), such as these, is to fire assay the whole parts separately. To sample them, since they all appear to be identical, I would probably just grab a part here and a part there - I can't see how splitting down the lot by coning and quartering or using a sample splitter would give much improvement. In this case, you can probably run 2 parts per fire assay but, if the total copper and nickel is more than about 2 grams, you may only be able to run 1 part per assay. Since organics are involved, the parts must be incinerated before fluxing. This is easily done by weighing the 2 parts and placing them in an empty assay crucible. Then put them in a hot (say, 1850F) assay furnace, with the door opened just a crack to let in a little oxygen, and burn them until they fall apart into white ash. This might take 45-60 minutes. or more. Occasionally, you might have to pull the crucible out and give it a stir with a small diameter steel rod. If they aren't burned completely and any carbon remains, you'll probably end up with a too large lead button. After incineration, pre-mix the flux in a separate crucible, pour it onto the ash, stir it all up, and run a normal fire assay.
samuel-a said:Chris.
It amaze me time and again, how you (and the other "veterans") seems to have the bigger picture in mind and are willing to share your point of view with such detail. For that i pesonally would like to thank you.
goldsilverpro said:The easiest and, probably, most accurate way on identical parts (at least, in appearance), such as these, is to fire assay the whole parts separately. To sample them, since they all appear to be identical, I would probably just grab a part here and a part there - I can't see how splitting down the lot by coning and quartering or using a sample splitter would give much improvement. In this case, you can probably run 2 parts per fire assay but, if the total copper and nickel is more than about 2 grams, you may only be able to run 1 part per assay. Since organics are involved, the parts must be incinerated before fluxing. This is easily done by weighing the 2 parts and placing them in an empty assay crucible. Then put them in a hot (say, 1850F) assay furnace, with the door opened just a crack to let in a little oxygen, and burn them until they fall apart into white ash. This might take 45-60 minutes. or more. Occasionally, you might have to pull the crucible out and give it a stir with a small diameter steel rod. If they aren't burned completely and any carbon remains, you'll probably end up with a too large lead button. After incineration, pre-mix the flux in a separate crucible, pour it onto the ash, stir it all up, and run a normal fire assay.
What flux composition will be needed for such material?
According to spec sheets, about 60-70% of package matrix is composed of fused silica with the rest being mostly epoxy of some sort (which wouldn't matter since incinerated)
Harold_V said:Keeping in mind I have never assayed, my experience in processing waste materials taught me that silica is not melted (about 3,300° F required to melt silica), but dissolved by soda ash. If there's an excessive amount of silica present, more soda ash should handle it in stride. I can't address the issue of the epoxy, but I certainly would recommend full incineration before any attempt at melting. A slag cover may preclude full incineration, otherwise.
I certainly agree with the comments about fluorspar. It does an amazing job of thinning slag--and is, indeed, very aggressive in dissolving things, including furnace lining.
Harold
Harold_V said:silica is not melted (about 3,300° F required to melt silica), but dissolved by soda ash.
You did pay attention to my mention that soda ash dissolves silica, yes?mic said:Silicon Carbide would work well.
mic said:Silicon Carbide would work well.
Actually I did pay close attention....I just didn't make the connection between silica and silicon carbide.I'm not sure why it didn't register in my head,I should have known that.Harold_V said:You did pay attention to my mention that soda ash dissolves silica, yes?
Frankly, the only thing that provides longevity is not using flux. High alumina, and similar products offer decent resistance to dissolution, but even they have a finite life. Remember, the purpose of using flux is to do exactly what it does---liquefy solids, at which time it also absorbs oxides and other contaminants. Samual will have to balance his needs and decide if using his alumna vessel is a wise decision. It will hold up better than silicon carbide or graphite, but it will slowly dissolve.mic said:Please advise,because this is something I will be starting as soon as next week(weather permitting).
Since I am using litharge(lead oxide) ,couldn't I use glass as my gathering medium?I am not sure what to call it other than that,since I technically cannot call it flux.Harold_V said:Frankly, the only thing that provides longevity is not using flux.
qst42know said:What is it you are working on mic?
Sorry guys,I have been hurt(yet again),and I've had to coordinate the rest of that big shipment from that company last week.And on top of all of that I have a very large shipment coming in tomorrow.samuel-a said:mic,
what are planing to smelt?
No. Glass will absorb prills and may keep them in suspension. When you gather, a metal is desirable, so it will alloy with the prills, making them larger, encouraging them to combine instead of remaining in suspension in the flux (glass). By the way, common glass is nothing more than silica dissolved in soda ash.mic said:Since I am using litharge(lead oxide) ,couldn't I use glass as my gathering medium?
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