Recovery of Phenolics From Tar
Distillation Waste Liquors
Via Solvent Extraction
W. M. Reiter, Engineer
A. N. Heller, Supervisor Industrial Waste Division
The Barrett Division, Allied Chemical and Dye Corp.
New York, N. Y.
In a paper presented at the 12th Purdue Industrial Waste Conference the authors reviewed some of the major factors to be considered
in the selection of either solvent extraction or steam stripping, as the
process of choice in the dephenolization of phenolic waste liquors. This
presentation will deal principally with the development aspects, and
some of the operating experiences incident to the Barrett phenol recovery
process located in Detroit, Michigan.
The Detroit Plant of the Barrett Division, Allied Chemical Corporation, is essentially a tar distillation plant. Coke oven tars, a primary
raw material, are distilled to produce such intermediate fractions as
carbolic oil, high flash solvent, creosote oil, and various types of pitches.
The carbolic oil is scrubbed with caustic soda for removal of tar acids
and fractionated for recovery of crude naphthalene.
Coke oven tars may vary in water content from 2 to 10 per cent by
volume. Modern practice usually requires the dehydration of tar prior
to distillation. This procedure usually obviates the need for the separation of water from the distillates, and results in a reduction of both the
volume and phenolics to be processed. At Detroit tar dehydration is
accomplished by feeding the heated crude tar into the lower section of a
stainless steel fractionating tower operating at atmospheric pressure. The
tower bottoms flow to a reboiler and then to a vapor or flash box for
final removal of water. The dehydrated or "DH" tar is then transferred to a tar still for separation into creosote oils, naphthalene oil and
pitch. The water vapor combined with some organics exits the vapor
box and is returned to the dehydration or "DH" tower. The overhead
vapor from the "DH" tower is a mixture of light solvent and water.
This stream is condensed and the phases separated. A portion of the
light solvent is returned as reflux to the tower; the water containing
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