Abstract: The raw coal treated by Hualong Coal Preparation Plant is found to contain a great amount of coarse intergrown coal particles, and after treatment with H.M. vessel, the rejected material is considerably low in ash,entailing consequently a big loss of coal in reject. Through analysis of the variation of ash contents of the rejects (> 1.8 g/cm³) after the raw coal is crushed to different sizes.The method of crushing liberation of the coarse-grained intergrown coal is adopted, and the SSC80200 double toothed-roll crusher is used to crush the raw coal to reduce the feed coal to H.M. vessel from a top size of 200 mm to 80 mm or 50 mm (adjustable). It is noted that the smaller the size, the higher the ash of the > 1.8 g/cm³ reject and the lower the loss of coal in reject, which indicates that by liberation of the intergrown dirts through further crushing of raw coal, it is possible to realize effective separation of high-ash minerals and low-ash coal components.Practice shows that an average ash content of the reject product can go up to 82% and the loss of coal in reject is reduced to 0.16%, which are up 8 percentage points and down 2.84 percentage points, respectively, from the previous figures. The method adopted provides a better technical solution to the separation of intergrown coal.