The effects of ultrasonic wave on heterogeneous coagulation and flotation separation of pentlandite-serpentine

Abstract

It is well known that in the flotation of copper-nickel sulfide ore, pentlandite and serpentine are easy to form hetero-aggregation, which makes it difficult to separate them. Therefore, dispersion operation is indispensable, including chemical and physical dispersion. Chemical dispersion is usually achieved by adding dispersing reagents, which is widely used in mineral flotation, while the study of ultrasonic dispersion in copper-nickel sulfide ores in physical dispersion is less reported. Thus ultrasonic dispersion technology was introduced to weaken the hetero-aggregation and to improve the floatability of pentlandite. Through the implementation of a series of conditional tests of influence factors including ultrasonic site, ultrasonic probe type, ultrasonic time, and ultrasonic power, the optimum ultrasonic dispersion system was demined, and the results showed that the ultrasonic power was the key factor affecting the dispersion of pentlandite-serpentine. Then the dispersion mechanism of ultrasonic was revealed by means of supernatant turbidity measurements, particle-size distribution (PSD) analyses, scanning electron microscopy (SEM), and atomic force microscope (AFM) in succession. Coupled with supernatant turbidity measurements, PSD analyses and SEM images of flotation concentrates all confirmed that the ultra-fine serpentine particles coating on the coarse pentlandite particles were effectively dispersed. AFM analyses depicted the morphological changes of surface roughness treated by different ultrasonic power, and confirmed that the ultrasonic power of 200 W could increase the surface roughness and floatability of pentlandite but decrease that of serpentine. Thus, the difference in floatability between the two minerals were enlarged so as to achieve efficient separation of the two minerals. The results of this research are helpful to understand clearly the mechanism of ultrasonic dispersion of pentlandite-serpentine, which provides an alternative dispersion technology and exhibits great potential for further study and application.