Methods for recovering white liquor and white liquor separation promoters

Abstract

This invention provides a method for recovering white liquor and a white liquor separation promoter, which can reduce the amount of white liquor contained in the lime sludge after recovering white liquor from the emulsion, thereby enabling more white liquor to be separated from and recovered from the lime sludge. The white liquor recovery method includes a white liquor treatment step, in which lime sludge is separated from and recovered from the emulsion, which is a mixture of white liquor and lime sludge produced during the manufacture of kraft pulp, by filtration. The method further includes a separation promotion step, in which a white liquor separation promoter containing at least a nonionic surfactant and promoting the separation of lime sludge and white liquor in the emulsion is added to the emulsion before or during the white liquor treatment step.

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