Process for removing pigments from waste paper

A process for removing pigment from waste paper pulp containing waste paper pulp fiber, which process comprises the steps of:

• detaching pigment particles from the fiber in the waste paper pulp;
• adding to the waste paper pulp a flotation composition comprising an ester of the formula
• R(OCOR.sup.1).sub.m or R.sup.4 OOC--R.sup.3 --COOR.sup.4
• wherein
• m is 1, 2 or 3,
• R in the case of m being 1 is C.sub.1 -C.sub.8 alkyl or a group of the formula --(CH.sub.2 CH.sub.2 O).sub.n --R.sup.2 with n being an integer of from 1 to 10 and R.sup.2 being C.sub.1 -C.sub.4 alkyl or hydrogen,
• R in the case of m being 2 is a group of the formulae ##STR3## P is an integer of from 0 to 10, R in the case of m being 3 is a group of the formula ##STR4## and R.sup.1 is C.sub.12 -C.sub.20 alkyl or C.sub.12 -C.sub.20 alkenyl, R.sup.3 is phenylene or C.sub.2 -C.sub.10 alkylene and
• R.sup.4 is C.sub.1 -C.sub.8 alkyl,
• and of from 0 to 10 weight %, referred to an ester of the above formulae, of a surfactant;
• collecting the pigment particles by froth flotation effected with the aid of the collecting and frothing and dispersing effects provided by said flotation composition, thereby separating the pigment particles from the waste paper pulp.