The bulk of the nickel mined comes from two types of ore deposits. The first are laterites where the principal ore minerals are nickeliferous limonite: (Fe, Ni)O(OH) and garnierite (a hydrous nickel silicate):
(Ni, Mg)3Si2O5(OH). The second are magmatic sulfide deposits where the principal ore mineral is pentlandite: (Ni, Fe)9S8.
|NICKEL IN INDIA|
Main nickel occurrence in India is found in the Sukinda Valley in Orissa in the overburden of chromite. The total resources of nickel in India are estimated at 189 million tonnes of which 42.1 million tonnes contains +0.9% Ni. Orissa hosts about 92% of the total resources.
All India total resources as on 1-4-2005 (provisional) are of the order of 188.71 million tonnes, all under Remaining Resources category. Out of the total resources 90.66 million tonnes are under freehold sector and 98.05 million tonnes under leasehold sector. Under leasehold 39.97 million tonnes are under public and 58.08 million tonnes under private sector. Out of the total resources 42.13 million tonnes are of 0.9% Ni; 93.53% are of 0.5 to 0.9% Ni and remaining of unclassified grade. Out of total resources 17,4.85 million tonnes are in Orissa, and the balance in Jharkhand, Nagaland and Karnataka.
In India, so far, no substantial magmatic Ni-Cu sulphide resource has been identified despite local abundance of potential host rocks. Nickeliferous laterites with low nickel 0.5 to 1.0% over the ultramafic complex of Sukinda has been estimated but appropriate mining and extraction technology is yet to be developed to use the ore. The situation calls for improvement in extraction technology and search for nickel in the layered complexes and komatiites of Southern and Eastern India.