No abstract

There is an increasing focus on the hydrometallurgical processing of nickel-rich laterite ore due to declining global reserves of nickel sulphides. The development of new technology called hybrid nickel leaching circuit that encompasses pressure acid leaching (PAL) and atmospheric leaching (AL) processes has made processing of low-grade ores (with nickel content as low as 0.5%) a possibility. However, significant challenges exist in lowering the operating costs for this new process including the reduction of sulphuric acid and the energy required to heat the pulp to the desired temperature (250oC). To address above challenges, a detailed understanding of the process chemistry together with interactions between unit operations feeding into and out of the system is required. To accomplish this, a software package with powerful convergence algorithms, control loops, background chemical equilibrium, aqueous thermodynamics and extensive databases containing information on the physical properties of desired components is needed. Using such a process simulator, it is possible to produce numerically rigorous mass/energy balances for as many variations of the model as desired. This allows enhanced analysis of the flowsheet, better process design, and ultimately, better business decisions. Although there have been several studies on hybrid circuit, most of these studies have only dealt with the effects of process variable such as temperature, acidity, pulp density. Thus far, no complete study has been published on the modelling of different proposed scenarios. The present work constitutes an effort towards bridging this gap. A number of possible flowsheeting combinations were simulated using a commercial software packages SysCAD, and some optimal configurations were identified.