Melting copper

[rontrusi]

What type of crucible can/should you use to melt copper.....steel, graphite...??

 

[peter i]

graphite/clay should be good (crucibles normally used for casting bronze)


Ferrous alloys should not be used for anything hotter than zinc (but can be used for aluminium)

Making good castings of pure copper is not the easiest thing to do.

 

[rontrusi]

I'm looking at just making a half way decent looking ingot.....nothing fancy, just a rectangular blob! lol

 

[butcher]

it will need a carbon source like charcoal to collect oxygen converting it to CO2 gas, or else you will just burn up the copper as Copper-Oxide.
copper is not as easy to melt as some of the other metals.

 

[rontrusi]

Ahhh crap! I was just hoping to melt some scrap wire into a few nice ingots. Sounds like it's going to be more trouble than it's worth.

 

[peter i]

and scrap wire will have a large surface area, making oxidation even worse before it melts.

You could build a small ytong furnace like this one
http://www.artmetal.com/files/imported/project/TOC/proces/cast/ag_cast.html
I have one that I use for melting silver, it works like a charm.


The author says that he has melted copper under a layer of powdered carbon, so cheer up, it's not impossible.

 

[madderoftime]

I've cast copper many times and had no issue with the oxidation. Once you get a melt going the Cu2O looses it's Oxygen to a lean flame in the furnace. I use a #10 crucible which holds about 31 lbs of copper and heat it with normal aspiration and propane. I leave the dampener wide open till around dull red then start backing it off and bringing the propane up in cfm.
If you are still interested I can help but please understand working with that much molten metal and also the fuel supply are dangerous if you don't take the proper precautions.
I use the wire and make bronze for investment castings of stamps
Pretty soon we will be casting a 30 lb. bronze nut for a huge book press I use.

 

[Lou]

Do you mean a rich flame? A lean flame would be more oxidizing...


I don't think it's that easy to melt copper, even in an electric furnace with graphite plates on top. The real deciding factor seems to be if you can get a hold of phoscopper or lithium.

Lou

 

[madderoftime]

You are right on the flame. What I ment was a burn that that is starved slightly for air.

 

[nivrnb]

I'm looking at just making a half way decent looking ingot.....nothing fancy, just a rectangular blob! lol

I know the feelings I wanted to make some copper spheres. I was taking copper wire to the scrap yard thinking I could make something out of this stuff to make a better profit.

The rectangular copper ingots came from an old heatsink.

nivrnb

 

[patnor1011]

They look cool.

 

[qst42know]

Is this what you had in mind Lou?

http://www.budgetcastingsupply.com/Phosphor-Copper.php

 

[goldsilverpro]

http://books.google.com/books?id=sxkPJzmkhnUC&pg=PA181&lpg=PA181&dq=oxygen+scavengers+added+copper+melt&source=bl&ots=AIqr0clxgU&sig=yNBnhnusVUiNfu2DbCjVplPoA5U&hl=en&ei=rdNjTqywDueAsgKT1qGXCg&sa=X&oi=book_result&ct=result&resnum=1&ved=0CC4Q6AEwAA#v=onepage&q=oxygen%20scavengers%20added%20copper%20melt&f=false

 

[qst42know]

Very potent stuff a teaspoon full in a hundred pounds. Or 57g per 100 pounds from the document GSP provided. That makes it a cheap addition as well.

 

[kadriver]

Get some refractory brick like this and carve a cavity from two of the bricks.

Then you can put a large melt dish in the cavity and melt all the copper wire you want.

I treated the melt dish with borax before I did the melt. Keep a mapp torch on the dish at all times and the copper will melt into a nice molten pool.

You can even pour them into nice ingots, like the ones pictured here.

kadriver