That is the "HPAL" approach (high pressure acid leach) also used at ravensthorpe and goro (i think) but ravensthorpe doesn't have a refinery. Sensitive to Mg grade which consumes the acid - sulphur for acid being a major cost driver. Alternative approaches are smelting to produce ferro-nickel or heap leaching. I am not confident on this but I think that Mg grade (wether it is a dominantly saprolitic or limonitc ore) would be one of the main considerations on the processing approach.
