Mechanism of a new combined collector for efficient flotation separation of cassiterite and calcite

The challenging separation of cassiterite from calcite by flotation stems from their similar floatability, requiring innovative combined collectors to improve process efficiency and selectivity. Here, a novel PTPA/FeCl 3 collector was developed by synthesizing p- tert -butylphenylhydroxamic acid (PTPA) with FeCl 3 . Microflotation tests showed that using PTPA alone yielded 81.80% SnO 2 and 45.87% CaO recoveries, whereas PTPA/FeCl 3 increased SnO 2 recovery to 89.51% while reducing CaO to 27.02%, demonstrating superior separation efficiency. Contact angle measurements confirmed enhanced cassiterite hydrophobicity from the mixed collector. SEM-EDS and XPS analyses revealed effective chemisorption of PTPA/FeCl 3 on cassiterite, where PTPA and FeCl 3 formed a stably adsorbed chelate complex. In contrast, calcite exhibited weak and unstable adsorption. The mixed collector thus combines strong collecting capability with high selectivity for cassiterite over calcite.