A series of experiments about thin-layer drying of dyeing sludge were carried out to investigate the effects of temperature and thicknesses on drying characteristics of dyeing sludge.The results were compared with that of paper mill sludge.By adopting different thin-layer drying models

the Modified Page model was finally chosen as the drying model to simulate the sludge drying process.Moreover

the effective diffusion coefficient and activation energy of the dyeing sludge was calculated.The results show that

the higher the drying temperature and the thinner the drying layer

the higher drying rate the dyeing sludge.Obvious difference existed between drying performance of different sludges.The thickness of dyeing sludge had more dramatic influence on the drying rate than the paper mill sludge.When the drying temperature was between 140 ℃ and 200 ℃

the effective diffusion coefficient of moisture in the dyeing sludge ranged from 2.966 7×10-8 m2/s to 8.388 8×10-8 m2/s

and the activation energy was 3.88kJ/mol

which was lower than the paper mill sludge(5.555kJ/mol).