The influence of ultrasonic pretreatment on the surface hydrophobicity of ultra-low ash coal prepared by anthracite flotation and bubble mineralization

Anthracite, due to its high fixed carbon content, is a vital stepping stone on the path to producing coal-based multifunctional carbon materials. However, excessive ash content in coal not only hinders its high-value-utilization, but also causes pollution to the environment after combustion. Reducing the ash content in coal and enhancing its utilization value have become an urgent matter. This paper studies anthracite and examines the ultra-low ash coal production process using ultrasonic pretreatment to improve the flotation process. Explore the most optimal flotation process and reagent regime. The results show that after ultrasonic enhancement flotation (one coarse and four fine stages), the ash content was reduced from 12.69% to 2.65%, and the yield was 16.01%. SEM analysis indicates that the ultrasonic treatment effectively cleans and disperses the mineral particles on the surface of the coal. The FT-IR and contact angle results indicate that the hydrophobicity of the coal surface has increased after treatment. The results of the optical microscope show that the ultrasonic treatment promotes the dispersion of the collector, the mineralization of the bubbles, and the agglomeration of the coal particles. This research provides effective approaches and references for enhancing the high-value-utilization and clean-utilization of coal resources.