Flotation of a South African low-grade banded iron formation (BIF)

Due to declining iron ore grades, low-grade ores with complex mineralogy — namely, banded iron formation (BIF) — are being explored to maximize iron ore resources and increase the life of mine. Flotation is the standard global process used for the beneficiation of BIF ores, as it is a complex ore reserve, and liberation is typically achieved below 1 mm. This study focuses on the flotation of a South African BIF, evaluating its response to different collectors, as well as effect of grind. As flotation is an expensive process and South Africa ranks high on the production cost curve, preconcentration by gravity or magnetic separation is performed prior to flotation. Thus, flotation was also performed on a gravity concentrate to determine if a grade suitable for steelmaking (approximately 63 percent) is achievable. The results indicate that the use of an alkyl ether amine-based collector partially neutralized with acetic acid is suitable for separation of hematite from illite and quartz at high pH values. Further optimization tests are being pursued to improve overall recovery and grade.