Determining the flotation upgrading effect of shale oil on lignite via molecular dynamics simulation and experiment comparisons

Abstract

ABSTRACT In this study, we combined experiments with molecular dynamics simulation to investigate the improvement of lignite flotation performance by shale oil and microscopic promotion mechanism. Through FTIR and GC/MS tests, our preliminary findings showed that shale oil contains polar groups and long-chain alkanes. Moreover, XPS tests confirmed that shale oil could render the C–C/C–H and cover the C–O, C=O and O=C–O functional groups. The induction time between lignite particles and shale oil bubbles was 15ms lower than that between kerosene bubbles. Besides, the flotation results indicated that shale oil could improve the yield and reduce the ash content of clean coal significantly. The molecular dynamics simulation results showed that shale oil molecules could preferentially adsorb on lignite pore surface and weak the direct adsorption and seepage of water molecules on lignite surface. This was consistent with the results of an analysis of the whole system’s relative concentration distribution and mean square displacement of water molecules. These data provide further evidence that shale oil can clearly improve the flotation recovery of low-rank coal, which is of great importance for the clean utilisation of low-rank coal.