In this study, a new jet-stirring coupling flotation device that incorporates the advantages of three conventional flotation machines (specifically, Jameson cell, mechanical flotation cell, flotation column) was designed based on jet suction. The suction capacity of a double cosine self-aspirated nozzle utilized by the device was analyzed under different feeding pressures, and the effects of frother concentration, feeding pressure, suction capacity, and height of sampling location on the bubble size distribution (BSD) were investigated using a high-speed video system. It was found that a large amount of air was sucked into the flotation cell by the self-aspirated nozzle arranged in a non-submerged manner, which met the requirements of flotation in terms of the suction amount of air. The suction capacity showed a positive linear correlation with negative pressure inside the nozzle. When the Methyl isobutyl carbinol (MIBC) concentration reached the critical coalescence concentration (CCC), the bubble size stabilized at approximately 0.31 mm, which was smaller than the bubble size produced by the conventional flotation machine. This indicated that bubbles suitable for flotation were generated. D₃₂ linearly decreased with increasing of feeding pressures and conversely increased with increasing suction capacities and sampling location heights, independent of the frother concentration.

Low-rank coal is difficult to upgrade using conventional flotation methods due to its high hydrophilic properties. Thus, it is necessary to explore new methods for upgrading and utilizing low-rank coal. In this investigation, a gaseous dodecane pretreatment method was used to enhance the flotation performance of low-rank coal. Pore distribution analysis, FTIR (Fourier Transform Infrared Spectroscopy), and contact angle measurements were used to study the surface properties of the coal sample. Size distribution and float-sink test results indicated that the coal sample contained a lot of clean coal with low ash content, which could be used as a high quality raw material for making coal water slurry. FTIR, pore distribution analysis, and contact angle results showed that the coal was very hydrophilic due to the high concentration of -OH group and the large number of pores and cracks on the coal surface. The hydrophobicity of the coal sample was significantly improved by the gaseous dodecane pretreatment method. Clean coal with 67.2% combustible matter recovery and 10.5% ash content was obtained by gaseous dodecane pretreatment flotation method. Coal water slurry with 60% concentration was prepared using the flotation clean coal.

The distortion process of kaolinite annealed from 25 °C to 550 °C for different holding times can be characterized using a thermogravimetric/differential scanning calorimeter (TG/DSC) for thermal analysis, X-ray diffraction (XRD) for establishing the crystal structure, the Fourier transform infrared spectrum (FTIR) for identifying the functional groups, and a scanning electron microscope (SEM) for establishing the microstructure. Dehydroxylation is the main reaction during annealing from 25 °C to 550 °C and leads to kaolinite crystal distortion. A stable crystal structure during distortion was obtained by optimizing the bulk phase with quantum chemistry. Then, the crystal structure was studied by using ab initio multiple scattering calculations for X-ray absorption of the fine structure (XAFS). The results of X-ray absorption near the edge structures (XANES) determined that peak shifts and intensity phases slightly increased. The crystal structure distortion of kaolinite during annealing can be explained by the experimental and simulation results. This work provides theoretical support for identifying kaolinite with different degrees of distortion and has the potential for further developments in coal gangue separation.