Importance

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Abstract

An improved process is disclosed for removing nonimpact inks and stickies contaminants from waste paper containing same by repulping the waste paper to form a slurry, adding a densifying agent and an agglomeration agent to the slurry, and subjecting the slurry to treatment with a conical cleaner to remove the inks/stickies. The densifying agent and agglomeration agent addition may be simultaneous or the densifying agent addition may precede agglomeration agent addition and, preferably, is conducted at ambient or greater temperature, at neutral to alkaline pH, and at a pulp consistency (below 18%). Densifying agent addition and agglomeration, followed by passing the repulped waste paper through a conical cleaner, provides improved ink removal over passing the slurry through a conical cleaner without such pre-treatment or with treatment only with densifying agent or only with agglomeration agent. Also, the process may be employed as an additional step in a conventional process for removing inks from reprographic printed papers, such as ink removal by screening, flotation, centrifugal cleaning, washing, and sedimentation with or without decantation. When the densifying agent is magnetite, the process may be employed with magnetic removal as an additional step.

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First Claim