The invention discloses a method for preparing high-purity bleached
broad beans from
agriculture and
forestry'three residues'. The method comprises the following operation steps: S1,
raw material screening: selecting'three residues' meeting requirements; s2, chipping is conducted, specifically, after peeling, chipping and screening are conducted, sheets meeting the requirements are classified and piled up; s3, washing with water; s4, cooking: removing hemicelluloses and
lignin in the sheets by adopting a
vapor phase prehydrolysis
sulfate cooking method; s5, pulp screening; s6,
oxygen dealkalization: adding a certain amount of
oxygen dealkalization into the collected material to carry out
oxygen dealkalization reaction; s7, bleaching: bleaching the material obtained after the oxygen removal reaction; and S8, sheet making and whiteness and
alpha cellulose detection: the product with the whiteness stabilized at 90% ISO or above and the
alpha cellulose content controlled at 90% or above is the final product. According to the method disclosed by the invention, by carrying out
physical property analysis and chemical component optimization on the
cutting residues, the material-making residues and the
processing residues, an efficient pulp screening, oxygen removal and multi-section bleaching process is developed, and the whiteness and the purity of the pulp are remarkably improved.