ABSTRACT
Refining by chemical transport involves the formation of a volatile compound of the metal to be refined by means of a reactive gas followed by its decomposition to yield the pure metal and to regenerate the reactive gas for recycle. The metal is thus transported from the impure solid form as a gas and then redeposited in another vessel as a pure metal leaving the impurities behind. The refining of metals by the thermal decomposition of their iodides is a process known as the Van Arkel and de Boer Process after its inventors. The carbonyl process is presently used exclusively as a refining process, recovery of nickel from laterite and removal and recovery of iron from ilmenite to get technical grade TiO2. Nickel carbonyl was the first metal carbonyl discovered; it was prepared by Ludwig Mond in England in 1890 and the refining process based on its utilization is sometimes known as the Mond Process.
