Date of Award


Document Type


Degree Name

Master of Science (MS)


Chemical Engineering


An alternate method to the conventional filtration for separation of mineral matter from dissolved lignite was investigated. Separation was accomplished by the introduction of an organic diluent mixed with the solid-liquid product from hydrogenation-solubilization of lignite and decanted at elevated temperatures and pressures. This method gave separation as high as 88 percent recovery of solvent refined lignite (SRL). The SRL contained ash as low as 0.70 percent versus 0.1 to 0.6 percent ash obtained by filtration methods.

The technique investigated is analogous to methods used in the deasphalting of petroleum residuum employed in the petroleum industry. The introduction of the diluent creates two layers, with the upper layer rich in dissolved lignite and the lower layer rich mineral matter. The separation is carried out at elevated temperatures and pressures by decantation through dip tubes.

Analysis of the data indicated that separation was significantly dependent on temperature, settling time and benzene to coal slurry ratio. The highest degree of separation was attained at 500°F settling temperature, with a settling time of 2 hours and a benzene to slurry ratio of 2:1.