| 摘要 |
1,249,569. Treating pitch. MIDLAND YORKSHIRE TAR DISTILLERS Ltd. 18 Feb., 1970 [18 Feb., 1969], No. 8736/69. Heading C5E. Coal tar pitch is upgraded by co-distilling the pitch with an oil derived from coal tar distillation and having 95% boiling in the range 210‹ to 320‹ C., and simultaneously or subsequently heating the distillation residue at 350‹ to 450‹ C. Thus a mixture of the pitch and oil may be heated up to 350‹ to 450‹ C., or the pitch may be preheated to 350‹ to 450‹ C. and the oil gradually added to the hot pitch. Oils mentioned include wash oil (B.R. 230‹ to 290‹ C.), naphthalene oil (B.R. 210‹ to 230‹ C.), and mixtures thereof. Co-distillation removes heavy oils that were in the pitch initially and makes the pitch more responsive to thermal treatment.
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