Nickel and cobalt are a pair of critical strategic materials with widespread utility. However, scarcity of their primary resources has led to an intense search for alternate resources. This paper discusses some of the flowsheets developed in our laboratory to recover these metals from by product resources like sulphide concentrate of uranium mining and nickeliferrous overburden from chromite mining, from industrial wastes like alnico scrap, spent catalyst and pickling sludge and also from ocean bed nodules. Salient findings on recovery of nickel values by electrolysis and cobalt powder by pyro-metallurgical operations have also been included.
Nickel and cobalt find widespread use both in the alloyed and unalloyed form, and as chemical compounds. Forming a triad with iron (they belong to the fourth period), the three metals are frequently present together in alloys. Both nickel and cobalt readily alloy with many other metallicelements to provide a wide range of versatile materials. While the major use of nickel is in stainless steels, the major use of cobalt is in cutting, wear resistant and hard facing alloys. Because the latter find application in defense related activities, nickel and cobalt are termed as critical strategic materials. In audition to tius, in the nuclear field, cobalt is employed as a sensor in self-powered neutron detector and also as neutron absorber in nuclear reactors. 60Co, produced by bombarding stable 59Co with slow neutrons, has application in radiation chemistry, radiography and food sterilization. Besides these, cobalt based alloys find application as body implants because of their excellent resistance to body fluids, good mechanical properties and their ability to be cast into intricate shapes. The chemical compounds of nickel and cobalt are used as colourants in glass and ceramics, as drying agents in paints and enamels, and in electroplating baths.
