Non-Chemical melting or seperating gold from fused silica

[butcher]

soda ash hard on dishes, get a couple or several, steve's prices are extremely reasonable. 8)

 

[Chumbawamba]

NEVER use unprotected metallic vessels to melt other metals.

Hi Harold.

I've been using cast iron pans to melt lead and have had no problems. Neither have the guys who do bullet casting:

http://castboolits.gunloads.com/showthread.php?t=34175

But I suspect you were thinking of different metals in this instance...ones with a bit more value than lead

 

[Harold_V]

NEVER use unprotected metallic vessels to melt other metals.

Hi Harold.

I've been using cast iron pans to melt lead and have had no problems. Neither have the guys who do bullet casting:

http://castboolits.gunloads.com/showthread.php?t=34175

But I suspect you were thinking of different metals in this instance...ones with a bit more value than lead

Yep! I should have been more specific. I, too, use an iron vessel for melting lead, and that has been common practice for years. Plumbers that used to do leaded joints used them routinely. There are other metals melted in iron vessels as well. Zinc comes to mind.

Lets approach this from a different perspective. In refining precious metals, there are no metallic vessels that would be suited to melting. Even if you found that the vessel didn't dissolve, the values would readily solder to the vessel, especially when using flux.

Harold

 

[Chumbawamba]

I've successfully melted zinc in my little iron melting ladle as well. It's harder to work with than lead and doesn't cast as well.

I've bought a few iron skillets from thrift stores for pretty cheap ($5-7 each) that I plan to use for melting. However, after reading the bullet casting thread that I posted above in my previous message, I'm going to be more discerning in my iron skillet purchasing. The vintage American made ones are supposedly the best, but then this is a bunch of rednecks talking over there so who knows

Sorry for the topic drift.

 

[Harold_V]

I feel the subject is within the scope of refining, considering anyone that intends to melt gold should have a basic understanding of acceptable melting vessels. I dare say several people will benefit, assuming anyone besides you and I are reading the posts.

The other consideration when using iron is that it is not fond of temperature change, unlike steel. When you heat a cast object unevenly, it is subject to cracking. If one deals with extreme temperatures, the odds of cracking are increased.

Harold

 

[Chumbawamba]

The general consensus of the bullet casting thread above was that you don't want to go banging your lead melting vessel. One of the posters recounted an incident where he banged his ladle against his melting pot to clear off some slag and cracked his vessel open. And it goes without saying that the thicker the walls of your pot the better it will hold up.

I recently learned the qualitative difference between iron and steel, something that I had not considered before I started getting into metallurgy. I am in the process of constructing a big mortar and pestle for crushing CPUs. I used some iron disks that I got out of a couple old brass lamps that I scrapped as the base plate for the steel tube I found for my mortar. I banged on them good beforehand and determined they were probably sound enough for the base plate, which will take a literal beating over and over again. My friend helped me weld up the parts I assembled. After everything was put together and after a brief moment of admiration, I was banging the larger steel disk we used for the platform with a hammer to even it out and the iron disk that we'd welded to the steel tube broke off at the welds. The weld was fine...it was the iron that fractured and broke off.

Iron is brittle. Steel is not. Steel good. Iron, not so much

Lesson learned.

 

[Harold_V]

After everything was put together and after a brief moment of admiration, I was banging the larger steel disk we used for the platform with a hammer to even it out and the iron disk that we'd welded to the steel tube broke off at the welds. The weld was fine...it was the iron that fractured and broke off.

Iron is brittle. Steel is not. Steel good. Iron, not so much

Lesson learned.

Iron can be strong, too, but it isn't common to find gray iron with strength. Ductile or nodular iron often rivals mild steel in strength, as can malleable iron. Unlike common gray cast iron, they can be successfully welded by conventional methods, too. It's the free graphite flakes in cast iron that raise hell with fracturing. Welding requires proper preheat and cooling to avoid problems, as you discovered.

All in all, a good learning experience, however!

Harold