Ozone micro/nanobubbles with catalytic processes are widely used in the treatment of refractory organic wastewater. Micro/nanobubble technology overcomes the limitations of ozone mass transfer and ozone utilization in the application of ozone oxidation, and effectively improves the oxidation efficiency of ozone. The presence of micro/nanobubbles keeps the catalyst particles in a dynamic discrete state, which effectively increases the contact frequency between the catalyst and refractory organic matter and greatly improves the mineralization efficiency of refractory organic matter. This paper expounds on the characteristics and advantages of micro/nanobubble technology and summarizes the synergistic mechanism of microbubble nanoparticles and the mechanism of catalyst ozone micro/nanobubble systems in the treatment of refractory organics. An interaction mechanism of nanoparticles and ozone microbubbles is suggested, and the proposed theories on ozone microbubble systems are discussed with suggestions for future studies on systems of nanoparticles and ozone microbubbles.

In this paper, the influence of Ca²⁺ on the flotation of a skarn type molybdenum ore and pure molybdenite mineral at pH 8 was studied using diesel as the collector. It was found that Ca²⁺ had little effect on molybdenum flotation at low concentrations. By further increasing Ca²⁺ concentration, the floatability of molybdenite—especially from the fine size fractions—was depressed even without the presence of fine gangue minerals. The mechanism responsible for the deleterious effect of Ca²⁺ on molybdenite flotation was studied by a range of techniques including zeta potential measurements, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectrometer (SEM-EDS) analyses and molybdenum phase analyses. It was found that Ca²⁺ interacted with molybdenite edges producing CaMoO₄ precipitates which were responsible for the depression of molybdenite flotation of Ca²⁺ by preventing the adsorption of diesel.

Nonpolar hydrocarbon oils are widely used as collectors for floating molybdenite. However, they can only adsorb on molybdenite faces and not on molybdenite edges, resulting in limited molybdenite recovery, especially in processed water containing a high amounts of Ca²⁺. In this study, the influence of Ca²⁺ and pH on the adsorption of polycyclic aromatic hydrocarbons (PAHs), as part of composite collection on molybdenite edges, was studied. It was found that PAHs could only adsorb on molybdenite edges in the presence of Ca²⁺. Ca²⁺ reacted with molybdenite edges to form CaMoO₄ precipitates. Then, CaMoO₄ precipitates interacted with PAHs to form a structure of π–cation–π by (1) the cation–π interaction, (2) the π–π interaction and (3) the electrostatic interaction. It was also found that CaMoO₄ precipitates on molybdenite edges promoted the adsorption of PAHs. The more the CaMoO₄ precipitates, the easier the PAHs adsorption occurred. As a result, the high amount of Ca²⁺and low pH enhanced the adsorption of PAHs on molybdenite edges. This study provides insights into reducing the deleterious effect of Ca²⁺ on fine molybdenite flotation.

Nonpolar hydrocarbon oil (NHO) is one of the most extensively used collectors in the flotation of molybdenite due to its excellent selectivity. However, NHO has low sensibility at pulp temperature. At low temperatures (<283 K), although more kerosene is used, the recovery of molybdenite flotation is still lower than at room temperature. In this study, magnetizing treatment, which is an efficient, low-cost, innovative, and environmentally friendly emulsification method, was used to improve the flotation performance of NHO in low-temperature molybdenite flotation. The test results showed that, compared with unmagnetized kerosene (UMK), the optimum dosage of magnetized kerosene (MK) could be reduced by 11% at 298 K. At the same dosage of kerosene, the flotation recovery of MK was 3% higher than UMK at 278 K. The surface tension measurement results showed that the surface tension of MK rose periodically as the magnetic field intensity increased, and there was a maximum surface tension within each period. Further, the magnetic field intensity had the maximum flotation recovery of molybdenite at the maximum surface tension of MK. Combined with the analysis based on the Girifalco–Good theory and the static drop volume method of interfacial tension, the interfacial tension of kerosene–water was shown to decrease with the increase of the surface tension of kerosene. This finding indicates that the dispersibility of kerosene in pulp could be improved by reducing the size of oil droplets, thereby improving the molybdenite flotation recovery of kerosene at low-temperature pulp. It is helpful to improve the flotation recovery of molybdenite using NHO as a collector for low-temperature pulp (<283 K).

With a telluride-type gold ore flotation concentrate as the research object, the Na₂S + NaOH collaborative leaching process was applied to selectively separate tellurium before the cyanide leaching of gold and silver. The effects of process parameters including the type of leaching agent, the amount of leaching agent, liquid-solid ratio, leaching temperature, and leaching time on the leaching rate of tellurium were investigated. The results showed that the tellurium leaching rate could reach 78.14% under the optimum conditions of −0.038 mm (95%) grinding fineness, 80 g/L Na₂S concentration, 30 g/L NaOH concentration, 4:1 liquid-solid ratio, 80°C leaching temperature and 3 h′s leaching time. The kinetic analysis showed that the leaching process of tellurium from telluride-type gold concentrate was a mixed type of chemical reaction control and diffusion control. The grain parameter in the leaching process was 0.26263 and the apparent activation energy E = 17.12 kJ/mol. Tellurium could be pre-leached from the telluride-type gold flotation concentrate through the Na₂S + NaOH alkaline leaching process to achieve the effective separation of tellurium from noble metals, which, when eliminating the adverse effects of telluride on the leaching of gold and silver, provides new ideas for the extraction of rare element tellurium.