| 摘要 |
1452615 Pulping wood with oxygen MO OCH DOMSJO AB 26 Oct 1973 [27 Oct 1972] 50025/73 Heading D2W In a method of pulping wood with a digestion liquid of pH 7-9 in the presence of oxygen, at least some of the digestion liquid is removed from the digester during and/or after digestion, treated so as to deactivate materials present in the liquid which tends to degrade carbohydrates during digestion and the deactivated liquid is returned for use in the same or another oxygen digestion method. The digestion liquid may comprise an alkali e.g. sodium hydroxide, carbonate, and/or bicarbonate. The deactivation treatment may comprise treatment with an oxidising agent e.g. air and/or oxygen and/or a peroxide and/ or heating to a temperature above that at which the liquid was withdrawn from the digester. Catalysts may be used to speed up the rate of deactivation. Deactivation may also be effected more quickly by irradiating the withdrawn liquid whilst deactivating the latter by treatment with an oxidising agent and/or heating at an elevated temperature. An alkali metal or alkaline earth metal hydroxide or carbonate may be added to the withdrawn liquid before and/or during deactivation. The wood may be pretreated with an alkali prior to oxygen pulping. |
