Froth moderating agent for controlling froth and reducing stickies in the flotation process for deinking waste paper

An aqueous pulp suspension consisting essentially of secondary fibers containing ink particles to be deinked in admixture with:

• (a) a chemical deinking agent in the form of displectors or a combination of frothers and collectors, and in an amount sufficient to deink the secondary fibers by flotation deinking in which the ink particles are separated from the secondary fibers and a froth is formed;
• and
• (b) a froth moderating agent, which is different from said chemical deinking agent, and which is present in a weight ratio of said chemical deinking agent to said froth moderating agent of between about 20:1 to about 2:1 effective to moderate froth in the flotation deinking of the secondary fiber, wherein said froth moderating agent is a combination of (i) and (ii)
• (i) a nonionic surfactant material represented by the formula:
• R--C.sub.6 H.sub.4 O--(C.sub.2 H.sub.4 O).sub.m --(C.sub.3 H.sub.6 O).sub.n --(C.sub.4 H.sub.8 O).sub.p --R.sup.1
• wherein R is an aliphatic hydrocarbon group containing from about 5 to 20 carbon atoms, R.sup.1 is selected from the group consisting of chloro, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.5 alkoxy and phenoxy, m, n, and p are each a number between 0 and about 30, and the sum of m, n and p is between 1 and 30;
• and
• (ii) fatty acid esters of sorbitan selected from the group consisting of sorbitan monooleates, sorbitan trioleates, sorbitan monostearates, sorbitan tristearates, and mixtures thereof;
• and further optionally
• (iii) alkoxylated fatty acid esters of sorbitan having a total of up to 50 alkoxy groups selected from the group consisting of ethylenoxy and propylenoxy groups, ethylenoxy and butylenoxy groups, ethylenoxy, propylenoxy, and butylenoxy groups, propylenoxy groups, butylenoxy groups, and propylenoxy and butylenoxy groups, provided that the numerical ratio of ethylenoxy groups, when present, to the total number of other alkylenoxy groups is less than 1;
• and/or
• (iv) a polypropylene glycol that is at least 50 weight percent soluble in water under secondary fiber deinking conditions.