Combined column and cell flotation process for improving clean coal quality: Laboratory-scale and industry-scale studies

Inherent limitation of the mechanical flotation cell is the entrainment of hydrophilic particles (gangue) in the water reporting to the froth. In this study, a combine column and cell flotation process was proposed to reduce the entrainment of gangue particles and, ultimately, ash content of coal flotation concentrate in Datun coal preparation plant, Peixian County, Jiangsu, China. The froth collected from the third and fourth cells of the 4-cell flotation machines in this plant was further re-cleaned to obtain qualified clean coal. Laboratory-scale results show that both the mechanical flotation machine and flotation column as re-cleaning flotation devices could produce the clean coal with qualified ash content. However, the yield obtained by the flotation column (84.49%) is significantly higher than that obtained by the mechanical flotation cell (68.21%). Industry-scale tests indicate the combined column and cell flotation process could produce qualified clean coal and run stably.