An Investigation of Approaches for Enhanced Reverse Flotation of Refractory Hematite Ore

As hematite ores become lower in grade, finer in grain size, and more complex in compositions, their beneficiation by froth flotation to produce the high Fe grade concentrate has become increasingly more difficult. A systematic and in-depth process mineralogy study based on the multi-element chemical and MLA analysis combined with other characterization techniques was conducted to explore the fundamental reasons for difficulties in refractory hematite flotation separation. The results show that the valuable mineral in the sample was mainly hematite and gangue mineral was primarily quartz. Hematite had a fine particle size distributed over a range of 0~45 μm with a degree of mineral liberation of 90.19%. The particle size of quartz was relatively coarse and was mainly distributed in the range of 20~150 μm with a liberation degree of only 67.72%. Unliberated quartz was mainly associated with hematite and the composite particle content was 36.44%. The rougher flotation tests produced a flotation concentrate of 66.71% TFe grade at a recovery of 65.47%. The screening analysis results with rougher flotation products indicated that the main reasons for the poor performance of rougher flotation were the serious entrainment of fine hematite particles and the difficulty in effective collection of coarse low-grade composite particles. Possible approaches for improving hematite flotation performance have been proposed based on the results from this study.