Fine ash contamination of froth in coal gasification fine slag flotation: Influence mechanisms of frother

In the coal gasification fine slag (CGFS) flotation process, there are issues relating to high reagent consumption and excessively high ash content of froth concentrates, to investigate the reason for high ash content of froth concentrates and the underlying mechanisms, this study examined the effect of methyl isobutyl carbinol (MIBC) on the particle size distribution of flotation products, as well as the distribution of residual carbon and ash in different particle size fractions. The results showed that the amount of fine-grained ash entrainment was over twice that of residual carbon, resulting the fine fraction of the froth as high as 75%. Analysis of bubble size and two-/three-phase froth characteristics revealed that MIBC dosage increasing reduced the bubble size while enhanced froth stability, thereby increasing the entrainment of fine particles by the water flow. FT-IR analysis and warp angle tests demonstrated that MIBC was adsorbed on both residual carbon and ash surfaces, with adsorption increasing as particle size decreases. Fine particles interact more readily with bubbles, thereby impaired the efficiency of fine particle separation. The findings of the above study provide a theoretical foundation and guidance for improving the separation efficiency of CGFS.