Dewatering of coal through solvent extraction

• Published in: Fuel (Guildford) Vol. 81; no. 11; pp. 1417 - 1422
• Main Authors: Miura, Kouichi, Mae, Kazuhiro, Ashida, Ryuichi, Tamura, Tomoichiro, Ihara, Takayuki
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2002; Elsevier
• Subjects: Applied sciences; Brown coal; Dewatering of coal; Energy; Exact sciences and technology; Fuels; Hydrogen bond; Low rank coal; Processing; Solvent extraction; Wood. Peat. Brown coal; Dewatering of coal; Solvent extraction; Low rank coal; Hydrogen bond; Lignite; Naphthalene(1,2,3,4-tetrahydro); Water content; Performance; Drying
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/S0016-2361(02)00059-5

A new non-evaporative coal dewatering method was presented, in which a bed of coal was contacted with a flowing non-polar solvent at less than 200 °C. Water in coal was released by thermal energy added and the released water was dissolved into solvent and was carried away from the coal bed. When the solvent was recovered at room temperature, most of water is separated from the solvent due to the decrease in the solubility of water in the solvent. Then the water is easily separated from the solvent by decantation. This method, therefore, removes water without causing phase change of water. When an Australian brown coal whose water content was 50% was treated by tetralin at 150 °C, the water content was reduced to less than 2%. This clarified that the presented method is more effective than the other methods from both the energy saving viewpoint and dewatering efficiency. The mechanism of dewatering was discussed based on the strength of hydrogen bonds formed between coal and water and the change in the solubility of water in the solvent with increasing temperature.