A Thermodynamic Analysis of the Selective Sulphidation of Nickel from a Nickeliferous Lateritic Ore

The production of a nickel sulphide concentrate through selective sulphidation of a nickeliferous lateritic ore at temperatures lower than current smelting temperatures, is being studied as a potential production method for upgrading lateritic ores. The ability to produce such a nickel sulphide concentrate at economically attractive grades, while achieving reasonable nickel recoveries, relies on the conversion of the maximum amount of nickel oxide to sulphide, while minimizing the amount of iron sulphide. This paper examines the thermodynamic basis for this selective sulphidation. The analysis includes both pure component equilibrium as well as various solid and liquid solution phases, which are anticipated to set limits on the maximum achievable grade/recovery combinations. Thermodynamic calculations show that, for high iron limonitic ores, grades of up to 20 to 25 mass percent nickel should be possible, while maintaining recoveries of greater than 80 percent