The goal of this paper was to study the possibility of concentrating iron ore by direct flotation with sodium oleate as a collector of iron minerals and a water glass as a depressant of the siliceous gangue. Following characterization studies of minerals and iron ore samples, fundamental studies with mineral samples of hematite and quartz were performed: zeta potential determinations and microflotation tests in a modified Hallimond tube. The isoelectric points of hematite and quartz were determined at pH = 7.5 and 1.8, respectively. The highest hematite floatability was achieved at 50 mg/L sodium oleate dosage, at pH = 7, and of quartz at 70 mg/L sodium oleate dosage, at pH = 9. It was observed from microflotation tests that the water glass was more effective in depressing hematite than quartz. The batch flotation tests confirmed the results of the microflotation tests. It means that the water glass is not conducive to selective flotation separation between hematite and quartz. The best results obtained with the iron ore sample (33.34% Fe and 48.02% SiO2 contents) were: an Fe metallurgical recovery of 88%, and Fe and SiO2 concentrate grades of 58.08% and 14.4%, respectively, achieved with 600 g/t water glass and 1200 g/t sodium oleate.
Direct flotation; iron ore; sodium oleate; water glass
