Phases transformation of nickel lateritic ore during dehydration

Abstract

The high magnesium nickel laterite ore need first be dehydrated if it is treated by the pirometallurgical means. The nickel laterite ore was dehydrated in a laboratory scale sintering pot in this study. The dehydration mechanism was studied by using the thermo-gravimetric (TG) tests, differential thermal analysis (DTA), and X-ray diffraction (XRD) experiments. The measurements indicated that chlorite (Fe,Mg,Al)6(Si,Al)4O10(OH)8 and serpentine Mg21Si12O28(OH)34H2O are the primary phases, while FeO(OH) and (Fe,Mg,)3Si4O10(OH)2 are the minor phases in the ore. The water in the ore can be divided as free water, crystal water, and hydroxyl group. During the heating process, the temperature range for the removal of the free water is 25~140˚C, for the crystal water it is 200~480 ˚C, and for the hydroxyl group it is 500~800˚C. The experiments with various coal dosages show that the temperatures of off-gas and burden increase with an increase in coal dosage. The sinter samples were analyzed using XRD. The results demonstrated that olivine (Mg,Fe)2SiO4 and spinel MgFe2O4 are the main bonding phases.

Keywords

• nickel laterite
• ferronickel making
• dehydrating
• sintering