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Abstract

A process is provided for purifying filter-clogging coal tar residue of the type obtained by low-temperature carbonization of coal. Such coal tar residues include viscous organic coal tar constituents, particulate solid impurities and liquid water. Applicants' process includes the step of heating coal at 450.degree.-700.degree. C. at least substantially in the absence of air to thereby decompose the coal to products including coal tar, the coal tar being of the type containing liquid water, particulate solid impurities, and viscous organic coal tar constituents including light oils, the light oils incidentally combining with the liquid water to produce a filter-clogging emulsion. The thus-formed coal tar is then heated to a temperature above the boiling point of water and sufficiently high to thereby distill off substantially all of the water and the light oils to thereby obtain an intermediate product which is substantially free from the presence of liquid water and light oil constituents which in combination form a filter-clogging emulsion. Finally, the intermediate product is subsequently filtered to thereby separate the particulate solid impurities from the undistilled viscous constituents of the coal tar.

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