The inhibitory effects of coal direct liquefaction residue (CDLR) on lignite pulverization were studied in a kilo rotary kiln during co-pyrolysis. Different CDLR to lignite quantity and particle size ratios were investigated in the study. The results showed that

with CDLR quantity ratio increased from 10% to 40% at 550℃

the co-pyrolysis char pulverization rate β was decreased from 7.55% to 1.98%

and the granulation rate λ was increased from 2.73% to 4.90%. Increasing CDLR quantity ratio effectively inhibited lignite pulverization and mixing granulation. Mixing 3-1 mm CDLR with 3-1 mm lignite reached the pulverization rate β of 2.82%

which is lower than the pulverization rate when mixing 6-3/13-6/25-13 mm CDLR with the same size lignite. Mixing 3-1 mm CDLR with 3-1 mm lignite reached the granulation rate λ of 24.99%

which was much higher than λ of mixing larger CDLR. Gray relational analysis indicated that the influence of CDLR size ratio on β and λ was greater than quantity ratio. A model of CDLR to lignite size and quantity ratio inhibiting lignite pulverization in rotary kiln during pyrolysis was constructed. The ratio factors affected pyrolysis along with other internal factors including strength of particle capturing

pore structure reinforcing and particle layer crossing behavior.