| 摘要 |
A versatile process and apparatus is presented for producing, in high yields, many different grades of pulp from a single wood specie or for pulping any specie or type of woody material, and for storage and recycling of the by-product liquid and gaseous materials. The process of this invention is virtually pollution free, and the reactant chemicals are recoverable from the by-products. In the alternative, the by-products themselves have a commercial value which may forestall recovery of the reactants. The lignin constituent extracted from the pulp is usable as a resin binder, a wood rehardening agent, or a glue. Depolymerization or digestion of the wood chips is achieved by exposure initially to ammonia and sulfur dioxide for from 10 to 60 minutes or more depending on the parent wood and pulp grade desired under controlled pressure and temperature conditions, and subsequently to sulfur dioxide from 10 to about 60 minutes also under controlled conditions of temperature and pressure in a digester vapor dome adapted to suspend a chip mass in the reactant gases. The digested chips are then defibrated in a lignin dissolving solution of monoethanolamine to extract the lignin constituent.
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