Effect of Power Ultrasound on Wettability and Collector-Less Floatability of Chalcopyrite, Pyrite and Quartz

Abstract

Numerous studies have addressed the role of ultrasonication on floatability of minerals macroscopically. However, the impact of acoustic waves on the mineral hydrophobicity and its physicochemical aspects were entirely overlooked in the literature. This paper mainly investigates the impact of ultrasonic power and its time on the wettability and floatability of chalcopyrite, pyrite and quartz. For this purpose, contact angle and collectorless microflotation tests were implemented on the ultrasonic-pretreated and non-treated chalcopyrite, pyrite and quartz minerals. The ultrasonic process was carried out by a probe-type ultrasound (Sonopuls, 20 kHz and 60 W) at various ultrasonication time (0.5–30 min) and power (0–180 W) while the dissolved oxygen (DO), liquid temperature, conductivity (CD) and pH were continuously monitored. Comparative assessment of wettabilities in the presence of a constant low-powered (60 W) acoustic pre-treatment uncovered that surface of all three minerals became relatively hydrophilic. Meanwhile, increasing sonication intensity enhanced their hydrophilicities to some extent except for quartz at the highest power-level. This was mainly related to generation of hydroxyl radicals, iron-deficient chalcopyrite and elemental sulfur (for chalcopyrite), formation of OH and H radicals together with H2O2 (for pyrite) and creation of SiOH (silanol) groups and hydrogen bond with water dipoles (for quartz). Finally, it was also found that increasing sonication time led to enhancement of liquid temperature and conductivity but diminished pH and degree of dissolved oxygen, which indirectly influenced the mineral wettabilities and floatabilities. Although quartz and pyrite ultrasound-treated micro-flotation recoveries were lower than that of conventional ones, an optimum power-level of 60–90 W was identified for maximizing chalcopyrite recovery.

The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation

“…Fig. 2 a illustrates the change in the DO content of the aqueous solutions under five different aeration rates (0, 10, 20, 40, and 80 mL/min) when the preparation time varies between 0 and 600 s. As can be seen, the DO level of freshwater without operating the device is around 8.5 mg/L, which is in line with the previous reports [56] . In overall, the DO content increases rapidly as the fine-bubbles generator runs, reaches a peak of 11.3–11.8 mg/L around 100 s, and then decreases gradually.…”

Ultrasonic treatment and its applicability for the selective treatment of borax clayey waste sludge

“…Both generation of free radicals and later also ability of the production of hydrogen peroxide, has been found that an effective tool for many surface cleaning and flotation applications of particles in literature (Farmer et al, 2000). This topic is well explored in a recent study performed by Hassanzadeh et al, 2021. As a result of the comparative evaluation of wettability measurements, in the presence of constant low-power (60 W) acoustic pretreatment conditions, the authors reported that all three minerals became relatively hydrophilic. In addition, except for quartz, the increase in sonication intensity increases the hydrophilicity.…”

A Review of Ultrasonic Treatment in Mineral Flotation: Mechanism and Recent Development

“…The reason for this was that ultrasonic cavitation destroys the hydrogen bond break in R-CO-NHOH, promotes its dissociation, increases the number of free ions in the solution, and increases the conductivity of the solution. Hassanzadeh et al [136] found that liquid conductivity slightly changed at a short ultrasonication time (t < 1.5 min), and then it dramatically increased from 2.2 µs/m (1.5 min) to 4.9 µs/m (30 min). The conductivity of the electrolyte increased with an increase in ion concentration in connection with a change in pH and the creation of highly reactive radicals (•OH and •H).…”

“…In addition, the introduction of ultrasonic cavitation leads the pH value of the pulp to decrease. Hassanzadeh et al studied the effect of ultrasonication on the floatability of minerals [136]. The results indicated that the average pH value was down from 7.8 to 6.4 after ultrasonic treatment for 30 min.…”