# Melting copper



## seawolf

An old friend of mine used to melt copper wire of smaller gauge and pour it into pans about the size of cookie sheets a quarter of an inch thick and the scrap yard paid him #1 copper price. Where he lived he had access to free natural gas. His kettle was an old stainless steel autoclave unit he had scrapped. 
After the insulation had burned off he added a flux to the copper as it melted then after the final skimming of the dross he added a second flux before the pour.
I can’t ask what fluxes he used as he has passed but I think they might have been the fluxes sold by ASi International. There web site can be found by googling copper fluxes.
I don’t know if this will help the backyard refiner or people who want to try a copper cell.
Mark


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## Harold_V

Not a lot of that makes sense. If you melt copper in the presence of stainless and flux, what prevented the copper from dissolving the stainless, or becoming firmly soldered to the stainless?
If you haven't poured molten copper, you'll come to understand that it's not as easy as you made it sound. It's a bitch to pour, due to its ready reaction with oxygen. It simply performs very poorly when melted. 

Harold


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## seawolf

I am not sure of the kettle it may not have been stainless. The second flux added just before the pour was to prevent oxidation and make it not require an inert atmosphere. I wish I had learned more and I also wish he were still here, I miss him greatly.
Mark


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## dtectr

Harold_V said:


> Not a lot of that makes sense. If you melt copper in the presence of stainless and flux, what prevented the copper from dissolving the stainless, or becoming firmly soldered to the stainless?
> If you haven't poured molten copper, you'll come to understand that it's not as easy as you made it sound. It's a bitch to pour, due to its ready reaction with oxygen. It simply performs very poorly when melted.
> 
> Harold


Plus the fumes can kill you ... or the neighbor's cat


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## Smack

I use borax. You don't put the borax in until the metal is molten. It will remove some impurities, just skim the slag off the top before you pour. I know there is something else you can flux copper with to remove impurities but not sure what it is. Think I read it once but I can't lie, I don't remember what it was. You can use stainless to melt copper, though it's not ideal for the task. You would want it thicker than say...sheet sst. I've used cast to melt copper in when I was first looking to melt copper. Was a dutch oven, and I still use it to melt aluminum, heck I've used that thing for sooo many different things, sure have gotten good use of it. Morgan Molten Metals http://www.morganmms.com/ has crucibles for every melting task. I use the A6 Salamander and have a A 10 Salamander on the way. Punch up A6 Salamander on ebay, Jets tools has them and a bunch of other stuff but no tongs yet. I made my own tongs for the A6. Aluminized Kevlar gloves are a must when working with molten metals, amongst other protective gear. Also, I pour into molds I made out of 4" channel with ends welded on.

As Harold said, you will have some stick to the cast as I did, but it just remelted on the next batch and when I knew I wasn't going to use the cast pot for copper any more I got as much out while it was still hot then after it cooled I sanded the inside smooth with a grinder and DA (dual action sander). And it's the same way with the aluminum, there's always some in the pot but that's fine as long as I stick to the same metal.


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## goldsilverpro

When refineries incinerate circuit boards and then melt the resulting metals into bars in a gas furnace, they are melting a multitude of metals together. The main metal is copper but, there are high melting point metals like iron, nickel, and cobalt. In order to reduce the melting point enough so the alloys formed will all melt within the temperature of the gas furnace, they often have to add additional copper. At any copper level, some of the Fe, Ni, and Co will alloy. To get all of the Fe, Ni, and Co melted, I'm thinking there must be at least 65%-70% copper. The melt then all becomes fluid and is cast into fairly homogeneous bars.

What I'm saying is that, if you melt copper in a cast iron, steel, or stainless crucible, you will definitely get some alloying. The copper will leach at least some of the iron (and maybe nickel, if stainless is used) into it. If the crucible is thin, holes in the crucible could result. In any case, the copper will be more or less contaminated. Bad idea to use any sort of crucible made of metal.


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## Geo

what about the sand molds the coppersmiths of old used?


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## Harold_V

goldsilverpro said:


> What I'm saying is that, if you melt copper in a cast iron, steel, or stainless crucible, you will definitely get some alloying. The copper will leach at least some of the iron (and maybe nickel, if stainless is used) into it. If the crucible is thin, holes in the crucible could result. In any case, the copper will be more or less contaminated. Bad idea to use any sort of crucible made of metal.


You know that, and I know that, but it borders on the impossible to have others come to the same understanding. Virtually no one seems to understand the solvent power of molten metals. Many deny it to be true. 

Harold


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