The Mechanism of Liberation of Nickel Oxide from Garnierite Ore by means of the Adding Iron Steam Roasting

Abstract

In order to make clear the mechanism of liberation of NiO from garnierite are by means of the adding iron steam roasting, high temperature solid reactions have been investigated with the coupling of Mg-Ni olivine and FeO and the coupling of garnierite are and iron powder. Moreover, the reactions were examined by means of X-ray diffraction and chemical analysis, and the mechanism was discussed kinetically. The results obtained are as follows.
(1) A large quantity of NiO were detected at the contacting surface of Mg-Ni olivine and FeO and that of garnierite are and iron powder. Ni rich points were found everywhere in the reaction layer, and the concentration of Mg and Si decreased remarkably at these points.
(2). X-ray diffraction peak of (222) plane of olivine in the roasted ores shifted from Mg₂SiO₄side to Fe₂SiO₄side with increasing the roasting temperature. This phenomenon seems to be due to increase of mol fraction of Fe2SiO4 in olivine.
(3) The reaction of liberation of NiO from garnierite are by means of the adding iron steam roasting seems to be expressed as follows.
(Mg_1-xNi_x) ₂Siat+2x FeO→(Mg_1-xFex)₂SiO₄+2x NiO
The selective extraction of nickel seems to become possible, because Mg and Fe in olivine are insoluble and free NiO is soluble in the dilute sulfuric acid.