Mineral separation by flotation is a water-intensive process; thus, recycling and reusing the process-water have essential environmental and financial impacts for ore beneficiation plants. The recycled water contains different ions, which affect flotation responses. Several investigations focused on the effects of monovalent and divalent ion contents of the recycled water and seawaters on the flotation recovery. However, there is a gap in exploring the influence of trivalent ions on the metallurgical responses of sulfide flotation. This work is going to fill this gap by exploring and comparing the effect of Na⁺, Mg²⁺, and Al³⁺ on the chalcopyrite and pyrite's flotation responses. Different flotation experiments and surface analyses were considered to assess and compare these multivalent cations' impacts on the flotation responses. Outcomes indicated that compared to Na⁺ and Mg²⁺, Al³⁺ could significantly change both minerals' surface properties, relatively improved pyrite's floatability, and decreased the chalcopyrite recovery. Adsorption of Al(OH)_3(s) on the minerals surface and the collector - Al(OH)_3(s) aggregate could explain these variations.