Effect of grinding media on the surface property and flotation behavior of scheelite particles

Abstract

Grinding for mineral liberation is a prerequisite for a successful flotation separation. Different grinding media produce mineral particles with different surface properties and flotability. In this study, the surface properties and flotation behavior of scheelite particles having a size of −74+38μm produced by ball and rod mills were studied through single mineral flotation experiment, scanning electron microscopy (SEM) observation, wettability measurement, and X-ray diffraction (XRD) test. The wettability and flotation results showed that, compared to the ball mill particles, the rod mill ones have a lower critical surface tension and thus a greater hydrophobicity when treated with the collector solution, and accordingly perform a better flotation recovery using oleate as the collector. In addition, the rod mill particles have a smaller specific surface area, so the full monolayer adsorption of the collector on their surfaces is achieved at a lower oleate concentration. The SEM analysis further confirmed that mineral grains obtained from the rod mill possess larger elongation and flatness values, which are essentially required for their attachment with air bubbles. The XRD observations revealed that mineral particles from both mills (i.e. ball and rod) have similar exposure intensity of abundant {112} surface. However, the rod mill particles have more {101} surface exposed, while the ball mill particles have more {001} surface exposed, leading to a stronger interaction of the collector with the rod mill particles. Keeping in view the stronger interaction with the collector and the easier attachment to air bubbles, the rod mill scheelite particles are deemed to be more hydrophobic and have a higher flotation recovery. These details studied will help establish the relation between the particle surface properties and the grinding media, and provide guidance for optimizing flotation separation.