The process of refining Nickel is called the Mond Process. It is also called the Carbonyl process and is one of the Nickel refining processes. Nickel usually comes in the form of Nickel oxide along with other impurities. A mixture of Hydrogen gas and Carbon monoxide gas is added to the nickel and this process is called syngas. Now the Carbonmonoxide reacts with the impure nickel. Only nickel reacts readily with CO unlike other metals. While the impurities remain solids, Nickel and carbonmonoxide together form Nickel Carbonyl gas. When this Nickel Carbonyl gas is heated, it decomposes to form pure nickel and carbon monoxide.