Flotation behavior and adsorption mechanism of (1-hydroxy-2-methyl-2-octenyl) phosphonic acid to cassiterite

The flotation behavior and adsorption mechanism of novel (1-hydroxy-2-methyl-2-octenyl) phosphonic acid (HEPA) to cassiterite were investigated by micro-flotation tests, zeta potential measurements, FTIR determination and density functional theory (DFT) calculation. The flotation results demonstrated that HEPA exhibited superior collecting performance compared with styrene phosphonic acid (SPA). The cassiterite recovery maintained above 90% over a wide pH range of 2-9 with 50 mg/L HEPA. The results of zeta potential measurement and FTIR detection indicated that the adsorption of HEPA onto cassiterite was mainly attributed to the chemisorption between HEPA monoanions and Sn species on mineral surfaces. The DFT calculation results demonstrated that HEPA monoanions owned higher HOMO energy and exhibited a better affinity to cassiterite than SPA, which provided very clear evidence for the stronger collecting power of HEPA presented in floatation test and zeta potential measurement.