Fuel Processing Technology, Vol.43, No.3, 191-212, 1995
BINDERLESS COMPACTION OF HOT-WATER FORMED COAL LOGS FOR PIPELINE TRANSPORT
Coal log pipelines will transport compacted coal through a water filled pipeline. To fully develop this technology and make it ready for commercial use it is necessary to make high strength, water resistant coal compacts. Means for making coal compacts without binders that are strong and water resistant enough for pipeline transport are not currently available. It is possible to make high strength coal compacts by several means. However, these compacts suffer from an excessive loss of strength when exposed to water. If logs are formed at a moisture content equal to the equilibrium moisture content for the coal, water absorption is minimal, and there is little loss of strength. However, for many coals, that equilibrium moisture content is high and logs formed at that moisture content have low mechanical strength. The moisture content of the coal compact can be lowered when the compact is formed under appropriate conditions. If the appropriate moisture, temperature and pressure conditions are created during the formation of a coal compact, the resultant coal compact＇s moisture content is also lowered. These compacts adsorb little water and retain their mechanical strength when exposed to high-pressure water. We refer to compacts formed in this manner as hot water formed coal compacts or HWF compacts. HWF compacts have performed very well in durability and strength tests and are believed to be suitable for coal log pipeline transport.