Process simulation and exergy analysis of two nickel laterite processing technologies

The results have been presented for the process simulation and exergy analysis on two different nickel laterite processing routes. These are Ferronickel production and high pressure acid leaching (HPAL). An exergy analysis undertaken using the simulation results. The process simulation was carried out by Aspen Plus with inputs from thermodynamic simulation of selective sub-processes using Factsage software. The exergy analysis includes the overall processing circuit as well as individual sub-processes. Furthermore, the exergy efficiency for the Ferronickel processing route was determined for the case of having a heat recovery steam generator (HRSG) and one without. The combination of performing overall process simulations, thermodynamic simulation of sub-processes and performing an exergy analysis is a new way to integrate these three approaches and knowledge that will benefit especially those working in mineral processing. It was found that the HPAL unit processes are relatively high in efficiency except for ammonium sulphate recovery (58.1% and 71.4%) due to heat required to concentrate and recrystallize the compound. The efficiencies of the Ferronickel unit processes are affected by the operating temperature. HRSGs are added to the downstream unit processes to recover waste heat generated from the flare and slag/matte cooling, giving a higher exergy efficiency of 91.2% and 94% respectively.