Assessing The Performance Of A Floatex Density Separator For The Recovery Of Iron From Low-Grade Australian Iron Ore Fines ? A Case Study

The quality of iron ore fines in terms of high iron content and low levels of deleterious impurities such as Silica, Alumina, Sulphur and Phosphorous is a critical parameter, in sintering and subsequent iron and steel making processes. As the higher-grade ores become depleted, there will be a stronger focus on treating lower-grade haematite/goethite ores and developing suitable beneficiation techniques to reduce the levels of impurities. Innovative flow sheets, based on new and commercially available technologies, is required. These will be needed to include gravity concentration devices, which can handle coarse and fine feed sizes. In this paper, efforts made to reduce the silica and alumina content of a low grade iron ore fines (<1.0 mm size) sample from the Pilbara region in Western Australia are described. The feed sample, a goethite abundant lower grade iron ore fines, which was a plant reject assaying 48.66% Fe with 13.61% SiO2and 5.09% Al2O3 was investigated. To this end, an experimental campaign was undertaken, and beneficiation studies were conducted on the sample using a Floatex Density Separator (FDS), a gravity device which can be operated for size classification and/or relative density separation. The objective was to produce high-quality iron ore material suitable as sinter feed. An iron concentrate with a grade around 57.0% Fe (Calcined Fe of about 63.0%) was achieved while recovering around 67.0% of the feed weight. In addition, a rejection of substantial content of Silica (>75%) and Alumina (>66%) was achieved while securing >77% iron recovery. On the other hand, sharp classification efficiency with low values of imperfection around 0.20 was obtained. Consequently, the response of the lower grade iron ore sample to FDS application, has vast potential to reject deleterious impurities as a single stage separating beneficiation equipment. Remarkably, it was demonstrated, that a great amount of goethite, abundant in lower grade iron ore fines/plant rejects, which are currently being either stockpiled and/or dumped as waste, can be treated using FDS application and potentially can add a significant value to the iron ore mining industry by recovering additional iron ore fines. Keywords: deleterious impurities, beneficiation techniques, classification, relative density separation