Non-Chemical melting dishes with 24kt gold in them

[Anonymous]

hey im new here and was woundering if anyone has an easy way to recover the gold from the melting dishes?

 

[Harold_V]

If you've used a decent amount of flux when melting, you shouldn't have much gold in the dish. I recall a purple haze around the tops of such dishes, along with some fine beads that failed to agglomerate with the general mass. To recover those, simply melt a button of gold, then roll it around the dish, touching the tiny droplets. They'll gladly join the mother load, assuming you have the dish fluxed properly. Too much is not good, nor is too little. For the record, the flux in your melting dish should be water clear, with no other color than purple. If it is anything more than that, the gold you're melting is not pure and should be refined.

If your flux is dirty, what works quite well is to heat the dish to redness, then sprinkle soda ash on the surface. Repeat, keeping a close watch on the dish. Soda ash will slowly liquify and thin the old flux, and will also dissolve the dish. It reduces the oxides of other metals, forming beads of metal that you swore were not there originally. Once you have the flux quite fluid, it doesn't hurt to introduce more borax. You'll know when you've taken the operation far enough, for the dish will have been returned to an almost new like condition, although it will now be thinner than it once was. When you have the dish cleaned to your satisfaction, pour the flux and metal into a cone mold to recover the button of metal without a struggle. Be careful when doing this operation------it's easy to actually dissolve a hole in the dish.

I had an asbestos pan that I used for all melting purposes. Anything that may have escaped from a melting dish was caught in the pan. I recommend one, but you are unlikely to find the asbestos today-----considering it is no longer considered wise to machine, and has been removed from the market.

Here's a picture of the pan I used to use, along with various ingot molds.

Harold

 

[skyline27]

What does flux do anyway? I recently melted gold for the first time. I used borax according to my instructions but I really don't understand it's purpose.

 

[macfixer01]

If you've used a decent amount of flux when melting, you shouldn't have much gold in the dish. I recall a purple haze around the tops of such dishes, along with some fine beads that failed to agglomerate with the general mass. To recover those, simply melt a button of gold, then roll it around the dish, touching the tiny droplets. They'll gladly join the mother load, assuming you have the dish fluxed properly. Too much is not good, nor is too little. For the record, the flux in your melting dish should be water clear, with no other color than purple. If it is anything more than that, the gold you're melting is not pure and should be refined.

If your flux is dirty, what works quite well is to heat the dish to redness, then sprinkle soda ash on the surface. Repeat, keeping a close watch on the dish. Soda ash will slowly liquify and thin the old flux, and will also dissolve the dish. It reduces the oxides of other metals, forming beads of metal that you swore were not there originally. Once you have the flux quite fluid, it doesn't hurt to introduce more borax. You'll know when you've taken the operation far enough, for the dish will have been returned to an almost new like condition, although it will now be thinner than it once was. When you have the dish cleaned to your satisfaction, pour the flux and metal into a cone mold to recover the button of metal without a struggle. Be careful when doing this operation------it's easy to actually dissolve a hole in the dish.

I had an asbestos pan that I used for all melting purposes. Anything that may have escaped from a melting dish was caught in the pan. I recommend one, but you are unlikely to find the asbestos today-----considering it is no longer considered wise to machine, and has been removed from the market.

Here's a picture of the pan I used to use, along with various ingot molds.

Harold

Hi Harold,
Thanks for your very informative post. I can recall as a teenager my father putting a Franklin Stove in our family room. He put this cement-like thin asbestos board over the drywall behind the stove, then covered that with a decorative face brick material that came in sheets. I was thinking some of that asbestos board might make a great working surface for melting and casting operations? If it's still made and available that is. It wouldn't have raised edges to stop spills running away, but it's very heat resistant.

macfixer01

 

[Harold_V]

Thanks, macfixer01 :wink:

The material in question was marketed under the name Transite. It is cement bonded asbestos, and totally heat resistant in that it won't burn---but it, too, is subject to thermal shock to some degree. If you were to concentrate a torch on a sheet, it likely would split from the point of the torch outward to an edge.

My pan was made from material that was 3/8" thick, drilled and tapped deep, to accommodate the longest SHCS's (socket head cap screws) that I could obtain. That way the thread was strong enough to hold the box together. I had to use care, because it was relatively fragile, but I used it for years, and let it go with the business when it was sold.

I didn't apply a torch to the box, ever. I had a 1-1/8" thick round piece of asbestos that was bonded by other means, a plastic of sorts, which would break down slowly when heated, but wouldn't ignite. I used this block to support my melting dish, and was still using it when I sold the business. I used that routine to avoid breaking the box from direct heat.

Notice the color on the box-----a general purple cast. I melted, literally, thousands of ounces of gold in that pan, so it gradually got coated with colloidal gold, thus the color.

You are highly unlikely to find such material today, but keep your eyes open if you see any old structures being dismantled. Asbestos was commonly used for siding and in some cases shingles, so the chance of finding some isn't beyond hope, but EPA takes one hell of a dim view of anyone handling the stuff without safety gear. Due to that, I'm of the opinion that if a structure is being demolished, those involved are mandated to handle the asbestos properly, including disposal at proper facilities. If that be the case, you'd be hard pressed to recover any for your personal use.

While everything that has changed is in the best interest of society, it sure is a lot harder to do these things today than when I got started.

Harold

 

[Harold_V]

What does flux do anyway? I recently melted gold for the first time. I used borax according to my instructions but I really don't understand it's purpose.

You can almost look at flux as a lubricant for molten metals. It serves various purposes, the most important being to absorb oxides, so you don't have a film of contaminants on the surface of metals. When you do have, it's difficult to get melted bits to agglomerate. If you've tried melting gold powder, especially dirty gold powder, without flux, you know that it resists forming a common mass. A pinch of flux and it quickly flows together.

If your flux was any color but purple, or dead clear after you melted your first lot, the color you see is the oxides that were absorbed by the flux. Purple is a sign of colloidal gold.

You can get a real good look at how flux works by soldering some copper pipe. Without flux, you have almost no chance of success, yet when the proper flux is applied, the solder will follow the heat of a torch and flow where you want it to go, firmly forming a tight bond with the copper.

In refining, you have to be a little bit selective in what you use for a flux. If you're working with pure gold, you don't want to reduce oxides, but you do want them dissolved and carried away. Borax does just that. However, even though some say that soda ash doesn't reduce oxides, the evidence at hand says that's simply not true. The method I described for cleaning melting dishes appear to create metal when there is none present. In the process, very dark and sticky flux is converted to a much lighter color and becomes more fluid. Tiny beads of metal magically appear, and are in keeping with the metals that had been previously melted in the dish.

One of the services I offered my clients was cleaning their melting dishes. It's best done in a fume hood, because a lot of fumes are generated. I charged nothing for the cleaning, and returned good and useful dishes to the owner----but I kept the metal that came from the cleaning process. I got paid for my trouble and expense, and the owner of the dish got back a useful melting dish. I'd do that for them until they were discarded.

Harold