Abstract
Developing flexible and scalable beneficiation routes is crucial to enhancing the resilience of rare earth supply. This study evaluates processing options for a monazite-rich ore sample from the Alces Lake Project (Saskatchewan, Canada) with a head grade of approximately 2% total rare earth oxides (TREO). Multiple strategies were assessed to manage silicate-rich gangue, size-dependent liberation, and inherent grade–recovery trade-offs. The work also examined early gangue rejection via physical preconcentration to reduce flotation mass pull, and the use of magnetic response differences to split the feed into more selective flotation circuits. Three alternative process flowsheets were developed and compared. Flowsheet 1 applied direct flotation with one rougher stage followed by regrind and three cleaning stages to maximize concentrate grade, producing a final concentrate of 7.6 wt% grading 20.4% TREO at 72.2% TREO recovery (7.6% mass pull). Flowsheet 2 combined 850 µm screening and dense medium separation (DMS) to reject low-grade floats, followed by flotation of the DMS sinks and scavenger flotation of reground sinks tailings; this route achieved approximately 70–75% TREO recovery with rougher concentrate grades around 14% TREO, with additional TREO recovered in the scavenger at lower grade (mass pull increased as recovery was maximized). Flowsheet 3 combined two-stage wet high-intensity magnetic separation (WHIMS) at 5 kGauss with separate flotation of non-magnetic and magnetic fractions, delivering a combined concentrate grading 8.44% TREO at 84.9% TREO recovery (19.7% mass pull). These results demonstrate practical, selectable processing routes for Alces Lake material, enabling flowsheet selection based on priorities of maximum concentrate grade, maximum TREO recovery, or reduced downstream mass handling through preconcentration.