Conference Proceedings
Iron Ore and Open Pit Operators Conference Proceeding 2026
Conference Proceedings
Iron Ore and Open Pit Operators Conference Proceeding 2026
Effect of roasting a South African low-grade iron ore on flotation performance
The future resilience of the iron ore industry is strongly dependent on developing efficient beneficiation circuits as iron ore is continuously in demand being primarily used within steelmaking industries worldwide, accounting for 98 per cent of iron ore consumption. Historically, high-grade iron ore was preferably mined as minimal beneficiation was required, however, due to depletion of high-grade Mineral Resources, iron ores with lower grade and complex mineralogy are being explored. A significant portion (~60 per cent) of remaining reserves are banded iron formations (BIF), which consist of iron-rich and silica-rich layers. Majority of BIF deposits are found in Australia, Brazill, Canada, India, Russia and South Africa. South Africa is the largest iron ore producer in Africa and is projected to have about 1.6 Bt (billion tons) of BIF material. Thus, to maintain profitability and sustainability, research into beneficiation of BIF material is needed to smoothly transition to low grade materials. High-grade ores only require crushing, blending and screening prior to any steelmaking processes. Whereas, low-grade materials require more beneficiation steps, such as gravity separation, magnetic separation, and flotation, to maximise recovery while achieving a suitable grade. However, even when the above techniques are used, recoveries may still be compromised due to various physical properties, complex mineralogy and chemical composition. Thus, the objective was to perform reverse cationic flotation, using an ether amine, on physically separated pre-concentrates to generate a premium product suitable for industry (>63 per cent) at the maximum possible recovery. The head grade of the ore was 32.9 per cent Fe, which increased to 39.3 per cent after roasting. Pre-concentrates were produced and comparatively assessed via shaking table, and roasting followed by low intensity magnetic separation (LIMS). The shaking table concentrate was graded at 55.1 per cent, with a 49.9 per cent recovery. Whereas the LIMS concentrate achieved a lower grade of 53.4 per cent, but at a significantly higher recovery of 85.9 per cent. Due to complex mineralogy, flotation has become the industry standard to effectively remove impurities from BIF material, however, it is an expensive process necessitating pre-concentration prior to flotation. The South African BIF used for the research is laminated and intergrown in nature, and contains hematite, hematite intergrown illite, illite, kaolinite and quartz. Unfortunately, the presence of certain impurities, such as illite and kaolinite, is detrimental to the flotation process and may result in poor recoveries. However, to ensure effective separation during flotation, in addition to pre-concentration, desliming was done before flotation. Reverse cationic flotation of pre-concentrates was performed using an ether alkyl amine, and a comparative analysis of the results was conducted to determine the feasibility of the processes and recommendations for further optimisation. The final flotation concentrates for natural and roasted hematite were graded at 63.2 per cent and 57.5 per cent, respectively. However, the Fe recovery of roasted hematite was 77.0 per cent, which is significantly higher in comparison to natural hematite, which achieved 32.0 per cent, justifying further optimisation of roasted hematite.
Contributor(s):
N Maistry and A Singh
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- Published: 2026
- Pages: 10
- PDF Size: 1.091 Mb.
- Unique ID: P-05394-G3T8B9