Sulphite lignin production process

Essentially all of the lignin commercially available is isolated as byproducts from either the sulphite or the kraft process. Table II gives a very conservative idea of annual lignin production in the United States (2) and worldwide 36). 

Many softwood and hardwood species, together with certain types of annual plants, have commercial interest as a source of cellulose fibres for the production of paper and board products. Thus, in technical fibre liberation processes, such as alkaline or sulphite pulping, huge quantities of lignin are dissolved as alkali lignin and lignosul-phonates, respectively. With few exceptions (see Chapter 10), these lignins are, however, never isolated, but burnt... 

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