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In order to optimize the capacity and separation performance of column flotation equipment, pressure difference method was used to monitor gas holdup in flotation column. By adjusting the feed rate and feed concentration, the variation of carrying capacity and gas holdup profile in the axial was analyzed, with their internal relations and effect on separation performance also investigated. It is shown that the axial gas holdup increases from the bottom to the top when the feed rate is less than critical velocity. But it is opposite when more than or equal to critical velocity, which decreases with the increase of feed concentration. Increasing feed rate, the carrying capacity fist increases and then decreases, whose inflection point just is the critical velocity. The feed concentration increase can help improve the carrying capacity and the combustible recovery within a certain range. The carrying capacity prediction model is proposed with the squared correlation coefficient R² = 0. 873, which achieves a relatively high fitting precision. [ABSTRACT FROM AUTHOR]

Processing objects is a kind of hard-to-float and high-ash fine coal which collected in Kailuan mining. Flotation rate experiment was designed for investigating the process characteristics of fine coal. Size analysis and density analysis of five cleans and fine-grained of the flotation rate experiment were studied. The mineral morphology of flotation rate experiment cleans was observed by scanning electron microscopy(SEM). The results show that fine mud contamination exists throughout the flotation process. The fine mud content in J1, J2, J3, J4 and J5 is similar, but gradually increases in its product. With the conduct of flotation, the flotation rate of high-ash fine mud (ash content> 50% ) reduces, and the operation recovery of fine mud per unit time also reduce. Flotation rate and cumulative yield of heterogeneity fine mud increase with its size and density reducing. The way of high-ash fine mud into clean coal products is mechanical entrainment and covering the surface of coarse-grained coal by SEM and Stokes number(St) analysis. [ABSTRACT FROM AUTHOR]

In order to study the selectivity of flocculant between coal and kaolinite in selective flocculation floatation, the adsorption isotherm and adsorbance difference of polyacrylamide onto kaolinite and coal was investigated. The laser particle size analyzer was used to measure the floes size distribution of coal and kaolinite in different polyacrylamide solution. Hydrodynamic radius and adsorption radius of polyacrylamide molecular were calculated to discuss its adsorption conformation. The adsorbance of anionic polyacrylamide onto coal is higher than that of kaolinite. The adsorbance difference between coal and kaolinite decreases with the increase of polyacrylamide molecular weight. The adsorbance of cationic polyacrylamide onto kaolinite is higher than that of coal, and the adsorbance difference is lower. Selectivity of anionic polyacrylamide with molecular weight 3x106 is the best. Adsorption process of coal and kaolinite is more accord with Langmuir adsorption model. The coal adsorbance of this polyacrylamide is 2.15 times larger than that of kaolinite. The indicators of particle size distribution, d10, d50 and d90 of coal floes are 8.42, 2.60 and 2.75 times of kaolinite floes, respectively. The calculated adsorption radius of polyacrylamide molecular is lower than its hydrodynamic radius. When different polyacrylamide is absorbed onto different mineral surfaces, the effect of compression or penetration with different intensity of polyacrylamide occurres. [ABSTRACT FROM AUTHOR]