Extraction of Limonite Nickel Ore of Tanjung Buli, Halmahera by Coal Roasting and Acid Leaching

This research aims to increase limonite nickel ore concentration by coal roasting and acid leaching process. The extraction of nickel by the pyro-hydrometallurgy method with coal reduction roasting and acid leaching was performed after the washing and drying process. Reduction roasting used 20 wt.% of coal with a temperature 500–800 0C and roasting time 20-60 minutes. Leaching process used HCl 1 :1 solution. In the washing and drying processes, the nickel concentration was increased by 13.72%. The roasting process at 500 –600 0C required roasting time for 40-60 minutes while at roasting temperature 700 0C, the required time for 20 minutes, faster than the lower temperature. In the leaching process, samples were reduced at higher temperatures resulting in a higher nickel extraction. Roasting reduction at 800 0C for 20 minutes has increased the nickel concentration by 29.33%. Leaching samples roasted at 800 0C for 60 minutes provide the best nickel extraction result with percentage ratio of nickel and iron as 14.42.