Sciencemadness Discussion Board

How to separate copper and carbon powder?

Rattata2 - 4-1-2011 at 15:58

I have a mixture of copper and carbon powder, the copper being made by reducing copper (II) oxide by reducing under heat with the carbon. I would like to separate the copper from the carbon powder (and perhaps any oxide left over, but that's later.) Is there any feasible way to do this?

inspector5 - 4-1-2011 at 20:56

I may be wrong and if I am someone smarter will surely correct me but the first thing I would try would be to suspend the mixture in water and wait a little and decant off what will hopefully be the carbon suspended then repeat until you remove most (or enough) of the carbon. How long to wait will have to be determined by observation. I believe that should work fairly well at separating the carbon out given a roughly 4:1 ratio of densities between copper:carbon but you will probably have any remaining copper(II) oxide spread between the 2 though I would predict predominately in with the metallic copper.

peach - 5-1-2011 at 04:37

It's not magnetic, they're both solids, they're finely mixed... that makes it tricky to physically separate them.

I was going to suggest you salt the copper into solution and filter it away, but that's going to give you salt back which will need reducing again.

If you can handle gases, you may be able to reduce the copper with monoxide, by heating the carbon, blowing air gently through it and out into a tube with the warmed copper in it.

Haven't checked.

Be VERY careful with monoxide.

It is odourless, metabolically and neurologically toxic.

There are numerous gases that will function as a reducing atmosphere.

Hydrogen can be used for this. You could generate a decent amount by reacting tin foil (what is backward brits call kitchen foil, and which is actually aluminium) with sodium or potassium hydroxide.

[Edited on 5-1-2011 by peach]

Saerynide - 5-1-2011 at 09:54

Like Inspector said, perhaps putting the powder into a long glass cylinder like 1 L graduated cylinder with water and shaking the whole thing. When it setttles, the copper should be on the bottom with the carbon on the top layer. CuO will be somewhere in between, but should be less dense than copper metal. Then you can syphon off the carbon layer like how you clean a fish tank. Maybe change the density of the medium if water isnt providing such a good separation.

The WiZard is In - 5-1-2011 at 13:34

Quote: Originally posted by Saerynide  
Like Inspector said, perhaps putting the powder into a long glass cylinder like 1 L graduated cylinder with water and shaking the whole thing. When it setttles, the copper should be on the bottom with the carbon on the top layer. CuO will be somewhere in between, but should be less dense than copper metal. Then you can syphon off the carbon layer like how you clean a fish tank. Maybe change the density of the medium if water isnt providing such a good separation.



Put in a long cylinder put a piece of pipe/tubing down to the bottom
and run air/or water through it. Adjust the speed so that the
lightest/least dense solid floats up/out. This process can - has been
nuanced for hundreds of years, principle to separate metallic ores.

cyanureeves - 5-1-2011 at 20:49

that chemistry fellow with the white beard on youtube told a viewer that copper salts can be smelted with addition of carbon.mine just go up in smoke.unless he only meant the carbonate.

Jor - 6-1-2011 at 02:57

Burn it and reduce the copper oxides.

hissingnoise - 6-1-2011 at 05:24

Quote: Originally posted by Jor  
Burn it and reduce the copper oxides.

Whoops! Ever decreasing circles . . .?

unionised - 6-1-2011 at 06:01

You could heat it and oxidise the carbon with CO2 or water but that would give you CO which isn't nice stuff to work with. If you burned the mixture to CuO and CO2 then reduced the CuO with alcohol vapour you would get nice clean copper.
Jor's suggestion isn't as silly as it might have sounded