Patent ID: 6287417
Filing Date: 2001-09-11
Classification: C02F,D21F,D21H

Abstract:
A method of separating a stream of foamable aqueous admixture recovered from a fibrous web forming process into a surfactant-enriched stream and a surfactant depleted stream, comprising:forming a stable-free-draining foam from said foamable aqueous admixture by passing a plurality of air bubbles therethrough, wherein substantially all of said bubbles are between about 0.1 and about 10 mm in diameter and said free-draining foam is sufficiently stable to allow a foam residence time of several seconds;draining surfactant-depleted liquid which is substantially free of entrained bubbles from said stable foam in the substantial absence of coalescence in said foam, thereby forming a surfactant-enriched foam and a surfactant-depleted underflow;separating the surfactant-enriched foam from the surfactant-depleted liquid forming a surfactant-enriched stream and a surfactant-depleted stream; andreturning said surfactant-enriched stream to said fibrous web forming process in the form of a stream separate from said surfactant depleted stream and having a concentration of surfactant exceeding that of said foamable aqueous admixture.