Sylar said:
Success !!!
I have before me now a bead of shiny silvery silverish silver!
Weight: 9 grams.
Congratulations! I knew you could do it! :wink:
What is the black smoke coming from the hot crucible? Silver vapor?
I don't have a clue. Unless you are overheating the silver, there shouldn't be any vapor coming from it, but you may be seeing other contaminants burning off. If you failed to wash the cemented silver well, you may be seeing some of the aluminum that was included. GSP or Lou may have an idea what you're seeing.
AgCl + borax = bubbling/foaming + Cl + Ag seems to happen at about 800°C, crystalising out metallic silver until temperature rises enough to melt the produced silver.
I'm short on the chemistry end of things, so I'm at the mercy of what I read, and don't often understand everything even then. In that regard, one of the things I have been lead to believe is that if you heat silver chloride without a reducer, it doesn't convert to elemental silver well, and much of it is lost as vapor, although I have no clue what form it might be.
Regards the above statement, I stand to be corrected, and the subject has come up before, but the evidence at hand, the result of using soda ash in that capacity, is hard to disprove.
I gathered from my research, long ago, that soda ash acts as a reducer. I've been told I'm wrong, but something has to explain the fact that you can heat an old contaminated dish that is heavily coated with borax, then add some soda ash to the mix and end up with metal that wasn't there prior to the addition of the soda ash.
As it mixes with the dirty borax, you start seeing bits of metal appear. Eventually the color of the dirty borax is much lighter, and a nice sized button of metal has appeared. That, to me, indicates that the soda ash is reducing the oxides that were absorbed by the borax. If I'm wrong, I stand to be corrected, but it will take a serious amount of lecturing to make me see it differently, considering I recovered well over 200 ounces of gold from waste materials, along with a like amount of silver, using that process.
What's so special about the borax that it helps consolidate the silver into a metallic state? Can anyone explain the physics of that to me?
Technically? No, I can't. But it does absorb impurities that might otherwise prevent the silver from fusing. It also "lubricates" the silver, allowing it to flow freely. You'll have to trust the input from others that understand chemistry far better than I do if that isn't correct, or isn't enough information. I gave it my best shot.
By the way, all my AgCl was dry.
The lump I have sound like a brick if tapped and I scrape off the amounts I test with (pretty easy) why does everyone insist to keep it wet?
To prevent you having to scrape off what you need! My normal process was to allow it to accumulate in a jar, even if it got well darkened by exposure to light. No big deal, all I was going to do eventually was recover the silver. By keeping it wet you can readily handle the material. I see no advantage to storing it dry----and scraping it to get it in condition to be reduced seems like a lot of wasted effort to me. I say keep it wet, if for no other reason, convenience. Others may have a different viewpoint. Maybe they'll chime in.
Other crucibles I found in my stock: Stainless steel.
What are the up and downsides of these?
For melting?
BIG MISTAKE!
Molten metals are strong solvents of other metals. That means that what you melt in a stainless vessel is likely to dissolve a portion, or all of the vessel used for melting. If you were to flux, you'd also solder the lot to the vessel. Assuming it was heated long enough, you'd dissolve the wall to the point where you'd spring a leak, losing your values. You'd also contaminate the values because of the dissolution of the vessel. Makes no sense to purify a metal, only to contaminate it with something different when melting.
You can dissolve gold in molten lead and never get near gold's melting point. Same applies to other elements. Do all your melting in non-metallic vessels. Even if they don't dissolve, they tend to solder to the vessel.
Harold