Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1977-01-27
1978-09-12
Corbin, Arthur L.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 35, 162 38, 162 82, 162 90, 423573R, 423DIG3, D21C 302, D21C 1112
Patent
active
041135539
ABSTRACT:
A process for pulping hardwood to produce cellulose pulp in good yield and of high quality, with a low requirement for causticized pulping liquor, which comprises in a first pulping stage pulping the hardwood in an alkaline pulping liquor containing sodium sulfide at a pH of about 10.5 to about 13 and at a temperature within the range from about 110.degree. to about 170.degree. C while generating hydrogen sulfide in situ by reaction of sodium sulfide with organic acids liberated in the pulping; and then in a second pulping stage, following directly after the first pulping stage, continuing the pulping at a pH higher than said first stage pH, within the range of about 12.5 to about 14 and at a temperature higher than said first stage temperature within the range from about 145.degree. to about 190.degree. C, in the presence of added alkaline pulping liquor comprising sodium hydroxide and sodium sulfide until cellulose pulp is produced.
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patent: 3874991 (1975-04-01), Kleppe
Corbin Arthur L.
Mo och Domsjo Aktiebolag
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