Investigation of the flotation behavior and interaction characteristics of micro-fine quartz and magnesite in a dodecylamine system under ultrasonic treatment

Ultrasonic treatment, as an important surface modification method, profoundly affects the flotation behavior of minerals. This study examined the impact of ultrasonic treatment on the surface properties and flotation performance of magnesite and quartz in a dodecylamine (DDA) flotation system. Atomic force microscope detection results revealed that the surface roughness and roughness size of both magnesite and quartz increased after ultrasonic treatment. Flotation tests indicated that the recovery rates of magnesite and quartz were lower after ultrasonic treatment. At pH of 10 and DDA of 75 mg/L, ultrasonic treatment led to a 0.66%, 3.46%, and 0.33% decrease in the flotation recovery rates for three different magnesite particle sizes. Following ultrasonic processing, the flotation recovery rates for three different quartz particle sizes decreased by 8.48%, 30.76%, and 43.69%, in that order. X-ray photoelectron spectroscopy detection results showed an increased presence of characteristic Mg and Si sites on the surfaces of magnesite and quartz following ultrasonic treatment. DDA acted on the surfaces of the two minerals through electrostatic adsorption and hydrogen bonding adsorption and repelled the flotation of minerals owing to the same charge as characteristic sites, thereby reducing flotation recovery. Adsorption capacity tests and contact angle measurements demonstrated a decrease in DDA adsorption and contact angle on the surfaces of magnesite and quartz after ultrasonic treatment, explaining the reduced floatability. Extended Derjaguin–Landau–Verwey–Overbeek theoretical calculations indicated that before ultrasonic treatment, there was a repulsive energy between magnesite and fine-grained quartz particles. After ultrasonic treatment, the interaction energy between magnesite and fine quartz particles is mutual attraction.