Metal Extraction & Forming Division National Metallurgical Laboratory, Jamshedpur 831 007, India Email: sushanta_sk@yahoo.com S K Sahu*, Vijay K Verma, D Bagchi, Vinay Kumar & B D Pandey Indian Journal of Chemical Technology Vol. 15, July 2008, pp. 397-402 Received 18 July 2007; revised 26 May 2008