Enrichment of a Nigerian chromite ore for metallurgical application by dense medium flotation and magnetic separation

Abstract

This study, focused on the beneficiation of a Nigerian complex chromite ore sourced from Tunga-Kaduka, Anka Local Government of Zamfara State, Nigeria, assaying 45.85% Cr2O4 and 54.15% mineral impurities, was enriched concurrently through sink floatation and magnetic separation techniques. The chromite ore initially analyzed to contain silicate impurities was found not suitable for metallurgical purposes. Thus, enrichment was examined through gravity separation studies using organic liquid with different specific gravities at 2.8, 3.3, and 4.0. The separation of chromite ore with lowest particle size fraction was done using Mozley mineral separator followed by the magnetic separation of the sink product by magnetic separator. The results obtained revealed about 77% of the total material containing 300 μm particle size, 52% ˂ 212 μm and 17% below 75 μm. Subsequent analysis of the beneficiated ore was carried out by wet chemical analysis and atomic absorption spectrophotometer. The results showed that Cr2O4 content increased to 78.34% from initial 45.83% with maximum Cr:Fe ratio of 3.2:1, representing 84.27% of chromium metal present in the ore. The enrichment of Cr2O4 obtained in this study could be found metallurgically applicable in the electro-deposition and ferro-chromium alloy production practices.

Improving the Quality of Ferruginous Chromite Concentrates Via Physical Separation Methods

“…In other words, a higher value of iron might have come from chromite particles as well as from the interlocking of iron-bearing minerals with chromite. This observation has been also reported earlier [9,28,41]. Therefore, the iron level in the concentrate can be lowered to only a certain extent, and beyond that, its separation is not feasible through the beneficiation.…”

“…It should be added that the higher centrifugal Falcon separator has not been studied for chromite ores although this device is widely used in the mineral industry [25,26]. There are published papers available on magnetic separation as well as roasting assisted magnetic separation to discard the iron-bearing gangue minerals [9,13,[27][28][29][30][31]. Flotation, selective flocculation, as well as magnetic carrier separation studies have also been carried out for different chromite ores to separate chromite from the gangue minerals [32][33][34][35][36][37][38][39].…”