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Abstract

A newspaper de-inking system and process require much less water than conventional de-inking systems and which require much lower capital expenditure. The system removes ink from newspaper pulp in a continuous process using one or more extractors each of which performs a de-inking operation equivalent to 6 or more stages of a conventional de-inking process using reactor tanks. Water and heat are conserved still further by employing an evaporator to separate pure water from the extractor effluent and by recycling the purified water to the extractor and to other components of the system. A particularly preferred extractor employs a counterflow single-screw conveyor the flights of which have slots formed therethrough which extend counter to the direction of screw rotation. The slots permit efficient extraction using relatively little de-inking solution and at the same time obviate the need to periodically reverse the direction of screw rotation to unclog the slots. The flow of de-inking solution through the pulp and flights is determined by the dimension, number, and orientation of the slots, and by the pitch of the screw conveyor.

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First Claim