Abstract
This study investigates the removal of silica and alumina as impurities from hematite based low-grade iron ore containing 34.18 mass% iron, 31.10 mass% of silica and 7.65 mass% alumina. Wet high-intensity magnetic separation (WHIMS) and reverse flotation (RF) were investigated. In WHIMS process, 93.08% of iron was recovered with a grade of 53.22 mass% at an optimum magnetic density of 10,000 mT, and pulp density of 2% used the L-4 machine. In RF experiments, optimal results showed 95.95% of iron recovered with 51.64 mass% grade using 1 kg/t of 1% alkaline starch as iron depressant and 1:1 mixture ratio of 0.75 kg/t DAA and NaOL as silica and alumina collectors. The designed multi-stage process involving feeding the concentrate from WHIMS into RF process reduced silica to 2.02 mass%, alumina to 1.04 mass% whilst recovering 81.94% of the iron with 67.27 mass% grade. As a result of this research, a process to produce high quality iron concentrate from hematite based low-grade iron ore with high iron recovery rate was constructed.
Highlights
This study investigates the removal of silica and alumina as impurities from hematite based low-grade iron ore containing 34.18 mass% iron, 31.10 mass% of silica and 7.65 mass% alumina
The designed multi-stage process involving feeding the concentrate from Wet high-intensity magnetic separation (WHIMS) into reverse flotation (RF) process reduced silica to 2.02 mass%, alumina to 1.04 mass% whilst recovering 81.94% of the iron with 67.27 mass% grade
The increase in demand for iron in the steelmaking industries and the depleting high-grade iron ores has led to the alternative extraction of iron from hematite based low-grade ores [1]
Summary
The increase in demand for iron in the steelmaking industries and the depleting high-grade iron ores has led to the alternative extraction of iron from hematite based low-grade ores [1]. Sanje ore of Nampundwe area of Zambia containing 31.10 mass% grade of iron and more than 38 mass% silica-alumina gangue minerals as impurities was used. The ore contains high alumina and silica and it is to be used as feed in steelmaking; these impurities adversely affect the production of pig iron and steel [3]. High silica and alumina form high viscous slag with greater volume in blast furnaces which requires more flux [4]. These impurities need to be removed before feed into the steel making process
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