The invention relates to a method for separating hemicelluloses from a
biomass containing hemicelluloses. The method includes the steps of: a)
extracting the hemicelluloses from the biomass containing hemicelluloses
by treating them with a complex compound in an aqueous solution, and
forming a soluble hemicellulose complex, and b) separating the complexed
hemicelluloses from the biomass. The method is especially suitable for
producing high-quality chemical conversion pulp from raw cellulose. The
products produced with the method of the invention have a high degree of
purity, and the method is extremely economical and causes few emissions.
Hemicelluloses in a pure form can be obtained as by-products of the
method.