reducing of metal Oxides in Hydrogen atmosphere

[rcarbon]

I am trying to reduce various oxides of metals like Cu, Ni, Fe, etc in box furnace at 600 - 700 C with atmosphere of H2 + N2, but all the metal gets black in color, Ideally it should shine.
Whats wrong with my process ?

 

[Geo]

melting oxides directly is not a good idea if you want to recover elemental metal. theres a few different fluxes that will assist you in recovering the metals. the ideal method would be to reduce the oxides to elemental metal before melting.

 

[butcher]

The Metals you listed would not reduce to metals in a melt, melting even the elemental metal would oxidize a large portion of the metal, for copper you would need a reducing flux (carbon, flour, or some carbon base material to collect the oxide and burn it off as carbon dioxide gas) so the metal would reduce to elemtal metal, Iron is much harder to reduce to metal lime and coke from coal (carbon) are used in special furnaces, you may get some to reduce in a flux melt like the ancient people done to make iron tools using coal (as a carbon source to form coke), this usually produced a metal that was lumpy full of impuritys and oxides and was heated repeadedly and hammered into a tool, straw and borax was used in the process the hammering forced out the oxide impurity in the lump, and combined the metal (crystals) to look more what we think of as metal.

 

[samuel-a]

rcarbon

Share more info about your setup.
Do you evacuate the gas mixture from the chamber and pumping new gas mixture? What it the proportions of H2/N2 ?
do you expose it to air while the metal is still hot?

Have you considered doing this in quartz tube instead of a box chamber?
Take a look at this simple setup:


Source: http://www.rsc.org/images/reduction_tcm18-188855.pdf


What is the purpose of this?

 

[NoIdea]

Afternoon All - You do run the risk of producing metal nitrides and the hydrogen needs to be pure and dry, wet hydrogen can explode. Any gas impurities will or may react with your metals.

Copper should reduce, nickel maybe but temperatures need to be higher above say 1000 deg.C and as for iron well that’s even harder, temperatures need to be at least 1100 deg.C, with above 1200 deg.C for any real success.

I would suggest you try and reduce the metal sulphates with hydrogen, giving the metal and sulphuric acid, kinetic would suggest better results.

So to summarize, crank up the temperature, you are running your system way to low.

Hope this helps

Deano