Study on lignite dewatering by vibration mechanical thermal expression process

• A new lignite dewatering process — vibration mechanical thermal expression (VMTE) process was studied.
• The dewatering efficiency could be enhanced by 10% by VMTE process compared to mechanical thermal expression (MTE) process.
• The vibration enhanced the volume reduction of lignite samples which is closely related to the residual moisture content of lignite by accelerating particles compaction and changing coal structure.

A new dewatering process — vibration mechanical thermal expression (VMTE) process developed from mechanical thermal expression (MTE) process was studied in this paper. The enhancement of moisture content reduction of Zhaotong lignite by vibration in VMTE process under different temperatures and pressure was determined. Compared to MTE process, the dewatering efficiency was enhanced by 10% by VMTE process with a vibration force of 5 kN in tested range. The moisture content decreased from 1 to 0.19 (g/g) (db) under the most severe processing conditions. The investigation was carried out to identify how variations in vibration force affect the dewatering during the VMTE process. The vibration was proved to enhance the volume reduction of lignite samples which is closely related to the decrease of moisture content by accelerating particle compaction and the change of coal structure. The increase of vibration force in a special range resulted in more severe reduction of moisture content than that out of the range. The reduction of moisture content caused by the vibration force increase in the range from 1 kN to 4 kN was 3.6 times that in the range from 0 to 1 kN. A limitation of dewatering caused by the increase of vibration force was expected to exist.