Method for recovering solvents through the use of an extender

Abstract

Method for the recovery of solvent from a solvent-based wash liquid containing non-hazardous waste resulting from an equipment cleaning operation. The wash solution typically averaging approximately 90 percent solvent and 10 percent resin, pigments and other dissolved or suspended solids is continuously tumbled in a tumbler/evaporator vessel together with a highly porous, adsorbent extender in granulated form, while maintaining temperatures sufficient to evaporate the solvent and prevent the solid matter from sticking together after processing. The extender is a substantially inert, material and may be selected from diatomaceous earth, powdered calcium silicate, powdered glass (100 mesh), oak sawdust (100 mesh), cedar sawdust (100 mesh), bentonite, charcoal (100 mesh) and ground corn cobs. The amount of extender introduced into the vessel is of the order of 5 to 20 percent by weight of the wash solution. The system may employ jacketed ribbon, double cone or rotating helix blenders. A blender of the type which tumbles and moves the extender and wash solution from an input end toward the output end thereof at a sufficiently low and steady feed rate may be utilized to provide a continuous process as opposed to a batch process, the residence time being sufficient to dry the solid residue.

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