Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With agitation or forced circulation
Patent
1979-06-15
1981-10-20
Bashore, S. Leon
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With agitation or forced circulation
162 65, 162243, D21C 910, D21D 528
Patent
active
042959276
ABSTRACT:
A wood pump slurry is treated with oxygen in a mill with little change to the process or structure of the mill. No special pressure tanks are required. The consistency of the pulp need not be altered for the treatment step. It may be treated at the usual process consistency of the pulp; e.g., it may be treated at the usual consistency of the pulp leaving a washer or subsequent steam mixer without additional dewatering or additional dilution.
The oxygen is added into a closed section of the system so that it cannot immediately vent to the atmosphere. Alkali should also be present when the oxygen is mixed with the slurry. The mixing should occur near to the point of oxygen addition.
The oxygen is inserted into the pulp slurry and mixed with the pulp slurry between a washer and the subsequent storage tank.
The mixing occurs in a relatively small mixter that intensively mixes the slurry and gas. The mixer has a mixing zone with a swept area of 10,000 to 1,000,000 square meters per metric ton of oven-dry pulp. A preferred range is 25,000 to 150,000 square meters per metric ton of oven-dry pulp and an optimum range of around 65,400 square meters per metric ton of oven-dry pulp.
Other systems and specific mixer designs are also disclosed.
REFERENCES:
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patent: 3293117 (1966-12-01), Pennington et al.
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patent: 3832276 (1974-09-01), Roymoulik et al.
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patent: 4039154 (1977-08-01), Peterson
patent: 4082233 (1978-04-01), Reinhall
patent: 4093506 (1978-06-01), Richter
"The Asplund RL 50 S Raffinator" Defibrator Oct. 1971.
"Rauma-Repola Double Shaft Mixer" Bulletin.
Kleppe et al. "Oxygen/Alkali Delignification at Kamyr Digester Blowline Consistency-A Status Report" Nov. '76, TAPPI vol. 49, No. 11.
"A Continuous Process for Oxygen Bleaching of Pulps" 23rd Alkaline Bleaching Conf. 1969, Myburgh et al.
McDonald et al.; The Pulping of Wood, vol. I, p. 751, McGraw Hill Book Co.; New York 1969.
Rapson "The Bleaching of Pulp" TAPP(I) Monogragh No. 27, 1963, p. 332 FIG. 15.22.
Battan Howard R.
Bentvelzen Jozef M.
Bepple Henry
Justice Dennis H.
Meredith Michael D.
Alvo Steve
Bashore S. Leon
Weyerhaeuser Company
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