Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Including recovery of organic by-product
Patent
1992-05-04
1993-08-10
Chin, Peter
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Including recovery of organic by-product
162 15, 162 29, 162 3011, 481981, 423DIG3, D21C 1100
Patent
active
052345467
ABSTRACT:
Off gases from black liquor heat treatment, evaporators, wood pulp digesters, etc. are treated to produce primarily hydrogen sulfide and sulfur free fuel gases such as methane, carbon monoxide, hydrogen, and ethylene. Then the hydrogen sulfide is used to produce sodium polysulfide in white liquor for cooking wood chips to produce pulp by the kraft process. Polysulfide may be formed in three different ways: by supplying air to a fuel cell into which white liquor and the hydrogen sulfide containing gas have been introduced; by bringing clarified white liquor and hydrogen sulfide containing gas into contact with a wet-proofed activated carbon catalyst and oxygen containing gas; or by bringing unclarified white liquor into contact with the gas and oxygen containing gas, with lime mud acting as a catalyst, and then clarifying the polysulfide-rich white liquor produced to remove the lime mud. The white liquor produced contains about 0.5-8% on wood sodium polysulfide.
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"All It Takes is MOXY: Mead Oxidation System Generates Polysulifide Liquor," Smith et al., Paper Trade Journal, May 1, 1975, four pages.
"The Lummus Pollution-Controlled Polysulfide Recovery Process", Fogman, The 1972 Alkaline Pulping Conference of Tappi, Sep. 1972, pp. 1-11.
"Polysulphide pulping of two Canadian softwood blends", Green et al., Pulp & Paper Canada, 76, No. 9, T272-T275, Sep. 1975.
Chin Peter
Kamyr Inc.
Nguyan Dean Tan
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