Study on carrier flotation of long flame coal

In order to improve the flotation effect of long flame coal and the utilization rate of low rank coal, the mechanism of long flame coal by carrier flotation was revealed. In this study, carrier flotation tests were conducted using long flame coal obtained from Shaanxi Yujialiang Coal Preparation Plant as flotation feed and −1.3 g/cm³ anthracite from Shanghai Miao Coal Preparation Plant in Inner Mongolia as the carrier. The XRD and particle size analysis of long-flame coal revealed high fine content and ash content, with gangue minerals mainly composed of quartz and kaolin. The existence of fine coal slime and clay minerals led to the production of fine slime cap and mechanical entraining, resulting in a poor flotation effect. The effect of carrier size and proportion on the flotation effect of long flame coal was investigated. The results indicated that the cleaned coal yield decreased with the decreasing carrier particle size, and that the cleaned coal yield increased by 3.89% while the cleaned coal ash content decreased by 0.17% when 0.5~0.25 mm anthracite was used as the carrier. Furthermore, the carrier recovery rate of flotation cleaned coal reached 98.48%, with the carrier effectively recovered when the carrier proportion was 10∶1. Additionally, the influence of long flame coal slime size on carrier flotation was explored. The results revealed that 0.5~0.25 mm carrier could effectively improve the flotation effect of −0.045 mm long flame coal, with the cleaned coal yield increasing by 9.31% compared to the single flotation of −0.045 mm slime. In conclusion, carrier flotation mainly improves the flotation effect of fine slime. SEM, floc image analysis, and EDLVO theoretical calculation demonstrated that the −0.045 mm long-flame coal adhered to the carrier surface through the hydrophobic force and formed a large number of flocs, thus improving the flotation effect of long-flame coal.