Studies on the extraction of nickel from a low-grade nickel-ferrous ore from Rajasthan

A low grade nickeliferous serpentine ore from Rajasthan analysing 0.33% NiO, 37.18% MgO, 38.45%%, SiO2 , 5.75% total Fe, 1.83% Al2O3 and with 16.19% L.O.I. was used for extraction of nickel by roast reduction and ammoniacal leaching. A maximum of 44% nickel recovery was obtained by reducing the ore at 700°C with hydrogen flowing at the rate of 30 litres/hour for two hours and subsequent ammoniacal leaching under atmospheric conditions for 16 hours. The nickel recovery could be raised to 54.5% by pressure leaching of the reduced ore for 5 to 6 hours at 70°C under a pressure of 5kg/cm2. (Mr. M.S. Mahanty, Junior Scientific Assistant, Mr. R.N. Misra, Scientist and Mr. P.P. Bhatnagar, Scientist, National Metallurgical Laboratory, Jamshedpur)