Mineralogical properties and fundamental mineral processing behaviour of the chromite contained in laterite leach residue

Abstract

In order to utilize chromite in the laterite residue discharged from the large-scale Ni-leaching plant in the Philippines, its state of distribution, mineralogical properties, grindability, floatability, and magnetism were investigated. Chromite particles are concentrated over a 37μm size range, and poor in liberation. There are three different groups of chromite (A, B, and C), categorized according to their polished section, chemical composition, lattice constant, and specific gravity. Some of these differences affect the mineral processing behavior to a considerable degree. The grindability of chromite in leach residue is relatively high compared with that of chromites from other regions. Flotation is controlled by interfacial electrical attraction when ionic collectors are used, and the flotation peak appears in the vicinity of the PZC when NaOl is used. The order of floatability among the three groups of chromite particles is A>B>C, which indicates that a difference in surface structure by group affects floatability. Chromite from leach residue reveals paramagnetism at room temperature. The higher the solid solubility of magnetic ions (Fe 2+, Cr 3+, and Fe 3+), the greater the susceptibility is. In other words, the susceptibilities among the three groups are in the order of C>A>B.