Abstract: The present invention provides a process for deinking printed waste paper comprising the steps of: a) converting the printed waste paper to an aqueous pulp slurry in a pulper, where ink is detached from paper pulp; b) subjecting the pulp slurry to flotation in order to remove hydrophobic contaminants including ink from the pulp slurry, said flotation being carried out in the presence of a deinking chemical additive comprising modified silica obtained by treating hydrophilic silica particles with a hydrophobic organic liquid or modified metal silicate obtained by treating hydrophilic metal silicate particles with a hydrophobic organic liquid or a mixture of such modified silica and modified metal silicate. The present invention increases the yield of the flotation step without affecting the brightness of the flotation accept.

Abstract: A method and use therein for inactivating hydrogen peroxide decomposing enzymes in the production of recycled fiber pulp and/or mechanical pulp comprising providing solid peroxygen to an aqueous process for fiber production.

Abstract: The present invention provides a process for deinking printed waste paper comprising the steps of: a) converting the printed waste paper to an aqueous pulp slurry in a pulper, where ink is detached from paper pulp; b) subjecting the pulp slurry to flotation in order to remove hydrophobic contaminants including ink from the pulp slurry, said flotation being carried out in the presence of a deinking chemical additive comprising modified silica obtained by treating hydrophilic silica particles with a hydrophobic organic liquid or modified metal silicate obtained by treating hydrophilic metal silicate particles with a hydrophobic organic liquid or a mixture of such modified silica and modified metal silicate. The present invention increases the yield of the flotation step without affecting the brightness of the flotation accept.