The black liquor chemical composition depends on the type of
the raw material processed, i.e. softwoods (such as pine), hardwoods (such as eucalyptus) or fibrous plants (such as bamboo),
as well as, on the operational conditions of the pulping stage. However, for all raw materials and pulping operational conditions used,
the black liquor can be considered as a complex aqueous solution,
comprising organic materials from wood or fibrous plants (lignin,
polysaccharides and resinous compounds of a low molar mass)
and inorganic compounds (mainly soluble salt ions). Hence, as
summarized in Fig. 1, the black liquor chemical composition affects
its properties, basically those that govern its behavior in the recovery unit