Abstract:

The lignite is low metamorphic grade coal, but hard to use effectively, Drying is the key process to the effective utilization of lignite , It is necessary to study the influence factors of lignite drying performance. Effects of particle size, temperature, ash content and dense medium on drying efficiency of fine lignite in an infrared moisture meter are investigated by drying experiment, This was followed by the analysis of the drying results by utilizing effective moisture diffusivity. The results show that particle size and temperature have important influence on drying efficiency, with the decrease of particle size, the drying rate increases and the effective moisture diffusivity drops.The drying rate and the effective moisture diffusivity exhibit an increasing trend with increasing temperature. Both the lignite drying rate and the effective moisture diffusivity decrease with the decrease in ash content. Interfusing dense medium (magnetite powder and magnetic pearls) has significant influence on drying efficiency, the drying performance gets stronger on adding dense medium. Amongst all, the magnetic pearls work best during the process of drying, and it can achieve the best drying performance when the content of magnetic pearls reaches 50%.

Key words: fine lignite, drying performance, dense medium, effective moisture diffusivity