US PATENT SUBCLASS 162 / 84
.~.~.~.~ Plural diverse stage treatment

Current as of: June, 1999
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162 /   HD   PAPER MAKING AND FIBER LIBERATION

1  DF  PROCESSES OF CHEMICAL LIBERATION, RECOVERY OR PURIFICATION OF NATURAL CELLULOSE OR FIBROUS MATERIAL {33}
70  DF  .~ Treatment with particular chemical {9}
82  DF  .~.~ Sulfur containing {1}
83  DF  .~.~.~ Sulfur dioxide or sulfite {1}
84.~.~.~.~ Plural diverse stage treatment {2}
85  DF  .~.~.~.~.~> Chlorine containing material in at least one stage
86  DF  .~.~.~.~.~> Alkali metal, ammonium, alkaline earth metal or magnesium hydroxide or carbonate in at least one stage

DEFINITION

Classification: 162/84

(under subclass 83) Processes in which the fibrous material is subjected to a plurality of separate dissimilar chemical treatments, at least one of which involves treatment with SO2 or a sulfite.

(1) Note. The separate treatments may differ in composition or concentration of the treating medium, temperature, or pressure, of treatment, etc.

SEE OR SEARCH THIS CLASS, SUBCLASS:

29+, especially subclass 36 for processes of sulfite digestion in which the waste liquor is regenerated, reclaimed, reused or recycled.