Chemical and physical modification of low rank coal floatability by a compound collector

Effective collectors are essential for improving coal floatability. In this investigation, contact angle, X-ray photoelectron spectroscopy (XPS), optical micrograph, field emission scanning electron microscope (FE-SEM), and flotation tests were used to characterize chemical and physical modification of low rank coal floatability by a compound collector consisting of coal tar and diesel. XPS showed that the C-C/C-H content on coal surface after compound collector adsorption was higher than that on coal surface after diesel adsorption. Optical microscope image results showed that compound collector produced more flocs than diesel, which increased flotation efficiency. Contact angle results showed compound collector enhanced coal surface hydrophobicity more significantly than diesel. FE-SEM images illustrated that coal surface after compound collector adsorption was rougher than that after diesel adsorption, which accelerated the rupture of liquid film between coal particle and bubble. Therefore, coal floatability after compound collector adsorption was much better than that after diesel adsorption.

Automated summary

The study demonstrated that a compound collector consisting of coal tar and diesel can effectively enhance the floatability of low rank coal by modifying the chemical and physical properties of coal surface. The compound collector increased the hydrophobicity of the coal surface, generated more flocs, and accelerated the rupture of liquid film between coal particle and bubble, resulting in improved coal floatability compared to diesel alone.