In this study, X-ray Photoelectron Spectroscopy (XPS) was used to analyze the elements on the surface of subbituminous coal , and reverse flotation was introduced to float subbituminous coal. The effect of ultra-fine coal on the flotation behavior of silica in coal reverse flotation was discussed by comparing the flotation performance with two different artificial mixed flotation feedings, with ultra-fine coal (UFC, −45 μm) or without ultra-fine coal. The comparison results showed that the existence of UFC reduced the flotation rate and the recovery of silica, as well as the separation efficiency of subbituminous coal reverse flotation. Compared to the flotation performance of feeding with UFC, the concentrate ash content of feeding without UFC was lower (9.18%), and the separation efficiency was higher (68.69%). Total Organic Carbon Analyzer was used to test the adsorption quantity of collector by coal and silica to explain the mechanism. Conclusions were obtained that ultra-fine coal particles could adsorb more collector due to their larger specific surface area, leading to less collector left in the pulp to float silica particles. Selective flocculation reverse flotation method could increase the separation efficiency of coal reverse flotation with appropriate dosage flocculant .
Particle aggregates induced by nanobubble (NB) bridging has been recognized as one of the main contributors to improve the flotation performance of minerals in NBs-associated flotation. Despite the numerous investigations in particle-NB interaction, scarce research on revealing the properties of aggregates induced by NBs has been conducted, severally limiting the further understanding of the NB-assisted mineral flotation. In this study, NBs were first produced based on the principle of hydrodynamic cavitation. The aggregates of ultra-fine coal particles with different hydrophobicity induced by these tiny bubbles was investigated, with the size distribution, structure, and strength features of the aggregates systematically explained accordingly. In this study, NBs remained stable in the aqueous solution for more than one hour, and the size of these bubbles expanded from 240 to 650 nm within this period. The aggregates of coal particles was significantly enhanced, especially for the more hydrophobic ones, which could be well reflected by the right-shifted particle-size distribution curve, the newly formed chain-structure aggregates, and larger apparent viscosity and shear yield stress of the coal pulp. Moreover, the flotation performance (both flotation recovery and flotation kinetics) of ultra-fine coal particles was remarkedly improved in the presence of NBs, confirming that NBs did benefit the ultra-fine coal aggregates.
危险品化学品经营许可证（带存储）