Could you please explain how it is possible to remove Cu and Ni from a mixture of Cu, Ni and Carbon ?

Answer 1

A pretty vague idea. Oxidize the carbon and turn it to CO2, let it go and since nickel is magnetic you just have to place a powerful magnet near it to extract the Ni leaving you Cu in the box. Place heated iron rods into the container in which there is CO2, that should antioxidize the CO2 turning it into C. Theoretical completely of course, not sure if it will work...

Answer 2

The way you’ve phrased the question “remove”, I think Neil’s answer is closest to the mark.

By remove you are asking just to get that Carbon out of your mixture, not to separate the components. So yeah, oxidizing would work nicely. Heat the mixture and introduce oxygen (AKA blast furnace). The carbon goes away as CO2. You are left with a carbon-less mixture.

Now how are you going to separate metal Copper from Nickel? Hint: one way makes a pretty blue solution, and leaves a grey-silver metal behind.

Answer 3

If you dissolve the mixture in acids (look up in which acid copper and nickel dissolve), they dissolve leaving carbon behind.