Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1981-01-26
1982-03-30
Kratz, Peter F.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
423207, 423561A, 423DIG3, D21C 1104, D21C 1112
Patent
active
043222668
ABSTRACT:
A Kraft pulping process by which spent pulping liquor is burned in a recovery furnace 12 to reduce inactive alkali sulfates therein to active alkali sulfides while producing molten smelt that when added to water forms green liquor and residual dregs bearing catalytic iron. The dregs are separated from the green liquor and divided into first and second portions. The first portion of the dregs is discarded while the second portion of dregs required to maintain a concentration of iron in the smelt at from 0.05% to 5% is recirculated back to the furnace to provide optimum catalytic reduction of alkali sulfates to alkali sulfides. A quantity of alkali metal compounds is added at 24 to the pulping liquor in line 10 to serve as a temperature depressor that, together with the co-addition of said dregs, lowers the temperature of the molten smelt in furnace 12 from approximately 800.degree. C. to a more favorable temperature of about 650.degree. C. where maximum reduction of alkali sulfates to alkali sulfides will occur.
REFERENCES:
Whitney (Editor), Chemical Recovery in Alkaline Pulping Processes, Tappi Monograph #32, 1968, pp. 59, 60, 115-117.
Birk et al. "Hydrogen Reduction of Alkali Sulfate", Ind. Eng. Chem. vol. 10, No. 1, 1971, pp. 7-13.
Combustion Engineering Inc.
Habelt William W.
Kratz Peter F.
Lang Wayne H.
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