Hydrothermal-mechanical Upgrading of Brown Coal

Abstract

In an effort to upgrade brown coal and produce a transportable fuel, a new upgrading process of brown coal, hydrothermal-mechanical dewatering (HMD), has been developed. The fundamentals of hydrothermal-mechanical dewatering of raw brown coal slurry have been studied over a wide range of process-related parameters. The results from batch tests have shown that the hydrothermal-mechanical dewatering process combines the advantages of hydrothermal dewatering and mechanical dewatering and consequently, with low input of energy, produces dry, dense and hydrophobic coal. The slurrification of upgraded coal can lead to a coal-water slurry (CWS) with a solids concentration as high as 60wt%, which is much higher than that from raw brown coal (below 30wt%). The reconstituted slurries show a strongly thixotropic behaviour and display good storage properties. Therefore, the CWS prepared from treated brown coal by HMD process could potentially be an export fuel.