Abstract: The serious fouling and slagging derived from direct combustion or gasification of high-alkali-coal limit the large-scale utilization of high-alkali-coal in Xinjiang area.The technology of coal grading pyrolysis does not have the conditions of high temperature and oxidizing atmosphere to trigger fouling and slagging problems,so it has broad application prospects.How to improve the yield and quality of oil and gas during coal pyrolysis is an important direction of research on the utilization of high alkali coal.With coal separation,the components of high oil yield can be concentrated and the adverse effects of alkali and alkaline earth metals( such as sodium and calcium) can also be reduced.In the paper,the vitrinite-rich coal in Baishihu with different density grades was separated by flotation and centrifugation with heavy organic liquid.Fourier infrared spectrum was used to characterize the surface functional groups of different density-level components.In addition,the thermogravimetric analyzer and Gray assay were used to study the change rule of pyrolysis characteristic parameters and dynamics parameters,and the distribution of pyrolysis products.The results show that for the components of Baishihu coal with different density grades,the hydrogen content and the H/C atomic ratio decrease first and then increase,while the oxygen content and O/C atomic ratio increase gradually.The functional groups of —OH are mainly carboxylic acid functional groups and phenolic hydroxyl groups,which are relatively enriched at the medium density fractions.With the increase of density level,the maximum pyrolysis rate and the rate of weight loss decrease gradually,and the activation energy and pre-exponential factors decrease first and then increase.The tar yield first decreases and then increases: the tar yield of BS_(<1. 3) is as high as 25.25% and BS_(>1. 6) is equivalent to that of BS_(1. 3-1. 4),about 15%.The vaporization of crystal water in clay minerals results in the highest moisture yield for BS_(>1. 6).