Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1980-03-03
1981-09-08
Smith, William F.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 30K, 162DIG8, 423207, 423232, 423DIG3, D21C 1104
Patent
active
042882869
ABSTRACT:
A cellulosic pulp and bleaching process is described. The process integrates two cycles, one is a digestor liquor cycle and the other is a sulfur cycle.
The digestor liquor cycle comprises the steps of digesting a fibrous cellulosic feed to form a pulp, separating the pulp and bleaching it in at least one stage with chlorine dioxide, evaporating and burning the remaining waste liquor to form a smelt, dissolving the smelt to form a green liquor and utilizing the green liquor, after recausticizing, as at least a portion of the feed stock for the digestor step.
The sulfur cycle of the present invention utilizes a portion of the green liquor of the digestor liquor cycle. The green liquor is carbonated to form a bicarbonate which is then stripped of H.sub.2 S. The H.sub.2 S is converted into H.sub.2 SO.sub.4 and utilized as a feed stock to a chlorine dioxide generator. The chlorine dioxide generator utilizes H.sub.2 SO.sub.4 as feed stock and produces Na.sub.2 SO.sub.4 as a by-product. The Na.sub.2 SO.sub.4 by-product from the chlorine dioxide generator is furnaced in common with the evaporated waste pulping liquor from the digestor liquor cycle to form a common smelt, which is dissolved to form a green liquor, a portion of which is used in the sulfur cycle and a portion of which is used in the digestor cycle.
REFERENCES:
patent: 3210235 (1965-10-01), Ferrigan et al.
patent: 3366534 (1968-01-01), Rapson
patent: 3508863 (1970-04-01), Kiminki et al.
patent: 3542511 (1970-11-01), Shah
patent: 3841961 (1974-10-01), Saiha
patent: 3954552 (1976-05-01), Lukes et al.
Gosz William G.
Hooker Chemicals & Plastics Corp.
Smith William F.
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