Bulk and surface characterization of laterite by various physico-chemical methods

Abstract

The laterite ore is of a mixed type with a predominant iron and silica content, and its surface is coated with oxides and silicon. The mineral contains goethite and chromite as major in metallic minerals, and quartz, serpentine, and chlorite as major in non-metallic minerals. Geothite containing Ni and Co, is highly composite with Ni, Co, Cr, Mn, and Al in its lattice. Differential thermal analysis with gravimetric change for the laterite shows the endothermic peak due to the loss of adsorbed water and dehydroxylation of the lattice with the OH vibration spectra of water by infrared spectroscopy, which furthermore identifies SiOSi and FeO. The Mössbauer effect of laterite indicates that the spectral parameters are presented for Al-substituted goethite and magnetite. The initial settling rate and final settling heights of laterite particles are almost the same in the range of pH values between 2 and 8, but the dispersion state occurs above pH 8. This dispersion takes place in less than — 12 mV in agreement with the coagulation-dispersion domain digram. The ζ potential of laterite particles gives the point of zero charge of pH 5. Atomic absorption analysis of the dispersion portion shows the increase of Ni content, while it indicates the decrease of Co, Cr, and Fe. Magnetic separation of laterite particles occurs at sizes coarser than 74 μm. In flotation for fine particles of both the dispersion and settling portions, α-nitroso-β-naphthol has an effect on the up-grading of Ni and Co.