Hpd, LLC

Veolia Water Solutions & Technologies North America, Inc.

Veolia Water Technologies, Inc.

Jean-Claude Gallot

Michael S Begley

In a digester, wood chips and white liquor are combined and cooked under pressure to pulp the wood. This produces black liquor which is concentrated and burned in a recovery boiler. The recovery boiler produces ash that contains sodium, sulphur, potassium and chloride. The ash is dissolved and subjected to a process that recovers sodium sulfate and burkeite. The concentration of potassium and chloride is reduced, in part at least, by subjecting the ash to adiabatic cooling in a crystallizer which produces glaserite and a purge stream rich in chloride. By leaching the glaserite, sodium sulfate is removed from the glaserite, leaving potassium sulfate. The recovered sodium sulfate and burkeite can be recycled and used as pulping chemicals. The removed potassium and chloride can be further treated or appropriately discarded.

Method for recovering pulping chemicals and reducing the concentration of potassium and chloride therein

A method for removing dissolved solids from a waste stream, such as that produced in flue gas scrubbing, through an evaporation-crystallization process operated at relatively low temperature. A waste stream is directed into an evaporator and heated at a temperature of less than 60&#xb0; C. at a pressure below atmospheric pressure. The waste stream is concentrated through the evaporation process and forms a slurry stream having crystallized solids. At the low temperature of evaporation, the solids crystallize at substantially lower temperature and the solution has a substantially lower boiling point elevation than at atmospheric pressure. The slurry stream is directed to a solid-liquid separator where the crystallized solids in the slurry stream are separated, producing a solid cake and mother liquor.

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Naperville, IL, United States of America

Jean-Claude Gallot