Nickel Heap Leaching Study - International Nickel Study Group

The Report's ContentsEXECUTIVE SUMMARY ..........................................................................5NICKEL HEAP LEACHING STUDY........................................................6SCOPE OF REVIEW ................................................................................... 6INTRODUCTION ...................................................................................... 7IMPORTANCE OF NICKEL ........................................................................... 7ECONOMIC TRENDS .................................................................................. 7NICKEL MARKET ...................................................................................... 8TECHNOLOGY .......................................................................................... 8FUTURE TECHNOLOGY TRENDS ................................................................. 9GOVERNMENT POLICY ............................................................................ 10GEOLOGY AND RESOURCES ............................................................. 12BACKGROUND ON NICKEL LATERITES ...................................................... 12CONTROLS ON LATERITISATION ............................................................... 12FORMATION CHEMISTRY ......................................................................... 13LATERITE STRUCTURES .......................................................................... 14PYROMETALLURGICAL PROCESSES ............................................... 15FERRONICKEL SMELTING ........................................................................ 15NICKEL PIG IRON ................................................................................... 16HYDROMETALLURGICAL PROCESSES ............................................ 18CARON PROCESS ................................................................................... 18HIGH PRESSURE ACID LEACHING ............................................................ 19ATMOSPHERIC LEACHING (USING H 2 SO 4 ) ................................................ 21ATMOSPHERIC CHLORIDE LEACH PROCESS (USING HCL) ......................... 22ATMOSPHERIC LEACH PROCESS (DIRECT NICKEL) ................................... 24SULPHATION ATMOSPHERIC LEACHING .................................................... 25HEAP LEACHING (USING EITHER H 2 SO 4 , HCL OR HNO 3 ) .......................... 26Crushing, Agglomeration and Conveying .................................... 29Stacking and Heap Construction .................................................. 29Heap Leaching and Solution Management ................................... 29Metal Recovery ............................................................................... 30Solution Neutralisation................................................................... 30Mixed Hydroxide Precipitation ...................................................... 30Residue Storage and Evaporation ................................................ 30Reagents .......................................................................................... 31Utilities and Services ...................................................................... 31Sulphuric Acid Plant ....................................................................... 31TECHNOLOGY COMPARISON ................................................................... 32