Investigation of the removal of silica, alumina and phosphorus from Sanje iron ore using magnetic separation

This study investigates the removal of silica, alumina, and phosphorus as impurities from Sanje iron ore using wet high-intensity magnetic separation (WHIMS). Sanje iron ore, found in the Nampundwe area of Zambia, contains low-grade hematite ore with a chemical composition of 48.90 mass% hematite (Fe2O3) and 34.18 mass% iron grade. The analysis revealed significant levels of silica and alumina at 31.10 mass% and 7.65 mass%, respectively. The study employed mineralogical analysis using X-ray diffraction, alongside mineral particle distribution analysis through scanning electron microscopy. The magnetic separation experiments were conducted to identify optimal parameters such as magnetic flux density, particle size, and pulp density. The results indicated that a magnetic flux density of 10 T optimally enhanced iron recovery to 93.08% with a grade of 53.22 mass%. The gangue mineral particles remaining contained reduced amounts of silica and alumina. A second stage of WHIMS further treated the concentrate, resulting in an additional recovery of 83.41% of iron with improved grade, alongside reduced silica, alumina, and phosphorus levels. This research establishes a two-stage magnetic separation process for enhancing the recovery and quality of iron from low-grade ores.