Evaluation of the Crago flotation process to recover the iron contained in the fine tailings of Mont-Wright mine

Overview & Synopsis

Mont-Wright mine is an important asset of ArcelorMittal located in the province of Quebec, Canada. This asset annually produces 25 million tons of iron ore concentrate with an assay of 66% Fe, achieved through a beneficiation circuit comprised entirely of spiral concentrators. Nevertheless, 45 million tons of tailings are discarded to the tailings dam and, due to the intrinsic inefficiency of the spiral concentrators used there, the iron content increases in the size fraction below 106 µm, which presents a good potential to be recovered. Thus, the Crago flotation process was evaluated to recover the iron contained in the finest fraction of the Mont-Wright tailings. Since it was patented in 1942, the Crago process with fatty-acid rougher flotation followed by deoiling and amine cleaner flotation has become the standard for phosphate flotation in USA operations. When applied to Mont-Wright tailings, the Crago process was able to produce a concentrate assaying 65.63% Fe and 2.14% SiO2, from a sample with 20.96% Fe. When compared to a usual reverse flotation circuit, Crago based flowsheet was more selective and presented better results.