The estimation method for the extraction yield of phenol on methanol-mediated extraction was developed using the kerosene fraction of Wyoming coal liquid. The extraction yield was estimated by Eq. 12 from the amounts of charged methanol (M) and water (W), and a partition coefficient (K), which was newly introduced.
K depended on the percentage of water in the charged methanol and water (Xw), but independent of the amount of charged oil. A high extraction yield was expected at Xw≤45wt%, while it increased at Xw>45wt%, suggesting a decrease of the extraction yield. Similar results were obtained for the extraction of cresols and ethylphenols. The contamination of neutral oil was very low at Xw>60 wt%.
From these results, several preliminary experiments are enough to estimate the extraction ratio using K, and the range of Xw=45-60wt% was adequate for practical processing. This estimation method is very useful for planning an extraction process.

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To separate polycyclic aromatic hydrocarbons from coal tar, which have very high melting point and difficult to purify, the pressure induced crystallization method was modified to use solvent and it was applied to the separation of anthracene from model mixture and real anthracene cake. At the condition of 333K, 150MPa, high purity anthracene crystal with 99.1 wt% was recovered from the model mixture by this method. The purification of real anthracene cake was also achieved by this method, however, the purity of recovered anthracene crystal was slightly influenced by the minor compounds in real anthracene cake.

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The study of coal liquefaction has been conducted since 1988 using NEDOL 1 t/d Process Supporting Unit (PSU) and the coal slurry operation time has reached 20, 000 hours. In this period, five kinds of coals, Taiheiyo, Wandoan (Australia), Illinois No.6, Wyoming (U. S. A), Tanito Harum (Indonesia) were used and the reaction conditions for the high oil yield were investigated. Moreover, the character-istics of the coal liquefaction catalyst were also invesigated. And the new operational information obtained and the new operational technology were developed.
In high calcium content coal, the formation mechanism of the deposited solid was elucidated and the withdrawal method of the deposited solid was determined.
In high ferric and sulphur content coal, formation mechanism of the deposited solid to the slurry preheater was elucidated and the prevention countermeasure was studied. In high moisture content coal, the plugging at the slurry preparation line occured and the mechanism of the increasing of the slurry viscosity was elucidated and the prevention countermeasures were studied. These operational analyses and developement will be re-flected to the operation of the scale up coal liquefaction plants in future.

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