outline the principle of the method used for refining of

A) nickel

B) zirconium

C) tin

1. Nickel Refining is done by Mond Carbonyl Process

This process is done by converting nickel oxides into pure nickel. This process uses monoxide property of forming complexes with nickel readily and reversibly to give carbonyl groups.

Following are the reaction steps

NiO  (s)  + H2 (g)   Ni (s) + H2O (g)


Then impure Ni reacts with CO at 60C and form Nickel Carbonyl


Ni (s) + 4 CO (g)  Ni(CO)4 (g)


When product heated to 250C, it decomposes to give pure Ni (s)


Ni(CO)4 (g) Ni (s) + 4 CO (g) 


2. Tin refining using various process

Electrolytic refining – Impure tin is put into an acidic electrolyte. Along with this thin sheets of pure tin is submerged in the acid. Once we apply electric current to both pure and impure tin. Tin dissolves from impure end and attaches itself to pure tin. It is a slow process can take upto 1 week.

Vacuum distillation – Impure tin is heated in closed vessel which is made up of graphite. When tin is hot, the air in the vessel is pumped out to produce vacuum. The impurities have different boiling points. Vacuum is adjusted to remove impurities and boil them away.

3. Zirconium is purified by Kroll process

Zirconium is first converted into Zirconium tetrachloride (ZrCl4) gas. Any leftover minerals or compounds are removed. Then zirconium tetrachloride vapour is then reacted with magnesium metal, forming magnesium chloride (MgCl2) and zirconium metal.

The magnesium chloride and any leftover magnesium are then removed.

This process produces granules of zirconium.

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