ZERO DISCHARGE PULP MILL

摘要

Apparatus for a pulp and paper mill, and methods of acting on liquid effluents produced in the mill, which minimizes the discharge of polluting gaseous and liquid effluents to the environment. Liquid effluents from the bleach plant (12) are concentrated (e.g. evaporated in 29, 30), incinerated (e.g. gasified in 32), leached (33), crystallized (e.g. freeze crystallized in 34) then washed, and then fed to the plant chemical recovery loop (19, etc.). White liquor produced from the recovery boiler (19) melt is fully oxidized and used in place of caustic in the bleach plant. Essentially all sulfuric acid, sulfur dioxide, caustic, and chlorine dioxide necessary for the pulp mill is produced from mill liquid effluents and gas waste streams, on site at the pulp mill. Typical bleaching sequences that can be used are DEopDnD, or AZEoPZP.