The real-time ash content measurement is the fundamental condition for the timely adjustment and intelligent control of operation parameters in coal production and utilization industry. In the present work, a real-time ash content analyzer based on the pseudo-dual energy X-ray transmission was developed. The feasibility of this X-ray ash content analyzer was validated by the linear relationship between ash content and five characteristic parameters of X-ray. The conditions of wave filter, tube voltage, and tube current were optimized. The comparison between the ash contents measured by muffle furnace and the X-ray ash content analyzer was conducted in laboratory and industry. It was found that the absolute error was smaller than 1% for clean coal with ash content of approximately 10%, and the possibility of the absolute error smaller than 0.5% was higher than 85%.

Preconditioning of coal tailings with flocculants is a useful technology to improve filtration performance. In this study, anionic and cationic polyacrylamides were used for the pretreatment coal tailings before filtration. Nondestructive and rapid measurement of the filter cakes of coal tailings...

In coal flotation, clean coal ash content is controlled by adjusting different operating parameters to meet the requirements for products. However, real-time control is strictly restricted by the traditional ash detection method, which is very time-consuming. Froth phase plays an important role in both transporting and upgrading flotation concentrate. The correlation between clean coal ash content and froth property is of great importance to monitor, predict, and control the flotation process. In this review, 14 important froth features related to the concentrate grade are summarized to comprehensively understand the complicated three-phase froth. Foam structure and foam destabilization mechanisms including foam drainage, bubble coalescence, bubble coarsening, and liquid film rupture are introduced, which help us better understand why the froth properties are related to concentrate grade. However, very coarse or highly hydrophobic coal particles could cause inconsistencies in the correlation between concentrate grade and froth properties compared with that in metal ore flotation. The challenges and suggestions in predicting clean coal ash content based on froth characteristics are finally discussed.