Greece is the only EU country with extensive nickel laterite deposits. Since the 1960s, the Greek laterites are treated for ferronickel production via a pyrometallurgical route. Currently, due to the rising cost of energy and the decreasing grade of mined laterites the pyrometallurgical treatment became economically marginal and for this reason alternative treatment processes are under investigation.
Potential applicability of hydrometallurgical treatment, using either H2SO4 or HCl, under atmospheric pressure conditions, was investigated in the present work. The laterite used contained 22.4% iron, 13.2% magnesium, 0.88% nickel and 0.06% cobalt. The investigated parameters were temperature (65-90oC), acid concentration (1-4 N) and solid to liquid ratio (10-30% w/v). High Ni extractions, almost 100%, were achieved with both acids. As far as Co extraction is concerned, HCl was found to be more efficient compared to H2SO4. The maximum achieved Co extraction was about 37% with H2SO4 and 96% with HCl.