International Paper Company

James A McCann

Alexander K Bonsu

Robert L Graff

Raymond Liu

Thomas E Amidon

Richard B Phillips

Jean J Renard

Linda A Beltz

Craig Forehand

Roger H Purrington

Wayne Christopherson

The specification discloses an apparatus and method for treating a slurry containing sodium sesquisulfate to recover sulfate and acid constituents therefrom. The apparatus includes a treatment vessel having a separation wall delineating a clarifying zone and a mixing zone. Slurry containing sesquisulfate crystals is introduced into the mixing zone along with water and the material is mixed to promote dissolution of the crystals and formation of sodium sulfate solids. Sodium sulfate solids are collected in a lower portion of the treatment vessel and conveyed out of the vessel, and liquid from the clarifying zone is conducted from an upper end of the treatment vessel to a conventional liquid processing unit. Treatment of a sesquisulfate-containing slurry in accordance with the invention provides sodium sulfate containing little or no sesquisulfate crystals thereby reducing the need for vacuum filtration or other expensive separation techniques to recover sulfuric acid and sodium sulfate solids from the slurry.

Apparatus and method for treating sesquisulfate waste streams

A method wherein waste cellulosic material is used as an alternative fiber source during chemical pulping to replace a fraction of the wood chips. The waste cellulosic material is fed to the digester along with wood chips. The waste cellulosic material need not be repulped or slurried prior to digestion. The wood chips may be any species of hardwood or softwood. Normal chemical pulping charges, temperatures and cooking times applied in the case of 100% wood chip pulping may be used for the co-pulping of waste cellulosic material and wood chips. Thereafter, the pulp is processed as usual for chemical pulping, including the steps of blowing the digester, washing and thickening the brown stock, and bleaching the brown stock under the normal conditions used for the component co-pulped with the waste cellulosic material. Further screening or cleaning steps may be required to remove debris from waste cellulosic material.

Method for co-pulping waste cellulosic material and wood chips

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Walden, NY, United States of America

James A McCann