Question

Name the method used for refining the nickel.

Answer 1

Hint: Refining is removing impurities or unwanted elements, typically as part of an industrial process. Just like refining sugar is done by using a boiling method.

Complete answer:
Sometimes this process is also known as the Carbonyl process, it is a technique used to extract and purify nickel. This process converts nickel oxides into nickel metal with very high purity being attainable in just a single process. This process has three steps:
Nickel oxide reacts with syngas to give nickel, together with impurities including iron and cobalt.
\[NiO(s) + {H_2}(g) \to Ni(s) + {H_2}O(g)\]
The impure nickel reacts with carbon monoxide to form the gas nickel carbonyl, leaving the impurities as solids.
\[Ni(s) + 4CO(g) \to NiC{O_4}(g)\]
The mixture of nickel carbonyl and syngas is heated to , resulting in decomposition back to nickel and carbon monoxide:
\[Ni(C{O_4})(g) \to Ni(s) + 4CO(g)\]
Mond process for refining the nickel is based on the principle that nickel is heated in the presence of carbon monoxide to form nickel tetracarbonyl, which is a volatile complex.
\[Ni + 4CO \to Ni{(CO)_4}\]

Then, the obtained nickel tetra carbonyl is decomposed by subjecting it to a higher temperature(450-470K) to obtain pure nickel metal.
\[Ni(C{O_4})(g) \to Ni(s) + 4CO(g)\]

The role of carbon monoxide is that the impure nickel is reacted with excess carbon monoxide at 5060C to form the gas nickel carbonyl, leaving the impurities as solids. In the Mond process for the purification of nickel, CO is passed over metallic nickel to given \[Ni{(CO)_4}\].

The Mond process is used to get pure nickel which is used in many applications.

Note: By using Mond process we obtained pure nickel by using the CO. Nickel reacts with the carbon monoxide, forming nickel carbonyl, a gas. The impurities remain in solid form. So they are easily removed by filtration.