Alkaline pulping of lignocellulosic material with amine and nitrate pretreatment
AssigneeMacMillan Bloedel Limited
InventorDavid M. Mackie
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Abstract
A method is described for increasing the yield of pulp obtained from an alkaline pulping process. A lignocellulosic material, such as wood chips, is first pretreated with an aqueous solution containing from 0.1 to 10% by weight of monoethanolamine, methylamine or dimethylamine and from 0.01 to 1% by weight of copper nitrate or nickel nitrate at elevated temperature and pressure in a closed vessel. This pretreated material is then subjected to conventional alkaline pulping, preferably soda or two-stage soda-oxygen pulping.
Claims10
In a process for pulping raw lignocellulosic material, the steps which comprise first pretreating the lignocellulosic material with an aqueous solution containing from about 0.1 to 10% by weight of a water soluble, low molecular weight aliphatic amine selected from the group consisting of monoethanolamine and methylamine and from about 0.01 to 1% by weight of a water soluble transition metal salt selected from the group consisting of copper nitrate and nickel nitrate at elevated pressure in a closed vessel and thereafter subjecting the pretreated lignocellulosic material to an alkaline pulping process in the absence of oxygen.
Dependencies are inferred from the claim text.