The Ontario Paper Company Limited

Canadian International Paper Company

Canadian Patents & Development Ltd.

Ernest Arthur Sexton

Ira E Puddington

Bryan D Sparks

Waste paper, particularly newsprint, is treated to release adhering ink particles (e.g. pigment carbon) from the paper fibers, and the ink solids (and organic contaminants) are then preferentially collected on the surface of inserted non-soap solids which have an affinity for, and are of larger size than, the ink solids. The ink-coated solids can be removed from the system by suitable physical means such as hydrocyclones, screens or decantation.

Ink removal from waste paper

A slurry of cellulosic material is diluted to a flowable consistency and subjected to a pressure differential on a permeable surface to increase the slurry consistency to a value between the consistency of the diluted slurry and the consistency of the slurry prior to dilution thereby forming a mat of cellulosic material on the permeable surface. The liquid and solids which pass through the permeable surface as a result of the pressure differential are recycled for use as slurry diluent, and to the mat of cellulosic material, while the mat remains on the permeable surface and subject to the pressure differential, is countercurrently applied, in a plurality of treatment stages, a treating liquid, such as a wash liquid, including application of a fresh treating liquid to said mat in the last stage of said treatment stages, whereby the treating liquid displaces at least a portion of liquid present in said mat from said mat and through the permeable surface in each treatment stage. The electrical conductivity of the liquid displaced from said mat in the last stage of said treatment stages is measured, and the amount of fresh treating liquid applied in the last stage of said treatment stages is adjusted in response to the deviation, from a predetermined norm, of the measured value of electrical conductivity of only the liquid displaced in the last stage of said treatment stages.

Process for treating a slurry of cellulosic material

A slurry of cellulosic material is diluted to a flowable consistency and subjected to a pressure differential on a permeable surface to increase the slurry consistency to a value between the consistency of the diluted slurry and the consistency of th slurry prior to dilution thereby forming a mat of cellulosic material on the permeable surface. The liquid and solids which pass through the permeable surface as a result of the pressure differential are recycled for use as slurry diluent, and to the mat of cellulosic material is applied a treating liquid, such as a washing liquid.

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St. Catharines, Canada

Ernest Arthur Sexton