Influence of monovalent and divalent cations on monazite flotation

Abstract

Understanding of flotation mechanism of monazite with oleate collector in saline water is essential for the rare earth mining industry. This work investigates the flotation performance of monazite in the presence of different ions such as Ca2+, Mg2+, Na+, and K+. The research integrates flotation experiments with colloid and surface characterizations using zeta potential, XPS and UV adsorption. The results showed that the presence of divalent metal ions (Mg2+, Ca2+) was highly detrimental to monazite flotation while the presence of monovalent metal ions (K+ and Na+) affected monazite flotation slightly only. The reason is that oleate formed insoluble products with divalent metal ions while the opposite is true in the case of monovalent metal ions. Therefore, the amount of soluble oleate ions in the presence of divalent ions was significantly reduced, resulting in less adsorption of oleate ions on monazite particles and thus reduced monazite recovery. The reduced adsorption of oleate on monazite was confirmed using XPS and UV adsorption experiments. This work explains the detrimental effect of various metal ions in saline water on monazite flotation.