Describe the principle involved in each of the following processes

Describe the principle involved in each of the following processes.
(i) Mond’s process for refining of Nickel.
(ii) Column chromatography for purification of rare elements.

i. Mond’s process for refining of nickel:
It is based on the principle of vapour phase refining:
This method is based on the fact that certain metals are converted to their volatile compounds while the impurities are unaffected during compound formation.
ii. Column chromatography for purification of rare elements:
This technique of chromatography is based on the principle that different components of a mixture are differently adsorbed on an adsorbent. The components of the mixture get adsorbed on the column at different places.