Enhancing cassiterite flotation by 1-hydroxydodecylidene-1,1-diphos- phonic acid (HDDPA)

The effective beneficiation of cassiterite from gangue minerals through flotation has gained significant attention due to the strategic importance of cassiterite. In the present investigation, the floatability of cassiterite was explored using 1-hydroxydodecylidene-1,1-diphosphonic acid (HDDPA) as a collector. Micro-flotation experiments demonstrated that cassiterite exhibited remarkable floatability within the pH range of 5.5-8.0, and HDDPA realized an efficient separation of cassiterite from calcite at pH around 6.0. Analysis of the zeta potential revealed that the negatively charged HDDPA anion overcame the electrostatic repulsion between the collector and the cassiterite surface, leading to its adsorption on the cassiterite surface. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the surface Sn(IV) of cassiterite interacted with the O atoms of the O-P(=O)-O group in HDDPA, forming a four-membered ring configuration that rendered the cassiterite hydrophobic. This work offers valuable insights into the utilization of novel collectors for achieving efficient flotation of cassiterite, especially for the fine fraction, along with an understanding of the underlying mechanisms.