The fiber obtained by cooking has a certain color, that is, the color pulp, and then with bleaching agent in the pulp lignin and pigment action, refers to become soluble or colorless substances retained in the pulp, so as to achieve the purpose of bleaching. In the inner layer of lignin, it is impossible to remove the cellulose completely by cooking without seriously destroying the cellulose, and bleaching is to remove the lignin purified pulp further under mild conditions. It can also be said that bleaching is the continuation of cooking.
Bleaching is achieved by using the lignin in the chemical pulp or by changing the structure of the lignin chromophore. The bleaching method can be divided into two categories: one is dissolved lignin bleaching, and the other is oxidized bleach. Such as chlorine, hypochlorite, chlorine dioxide, peroxide, oxygen, ozone, this method is often used in chemical pulp bleaching. The other is lignin-retained bleaching, which is usually bleached with oxidizing bleach, hydrogen peroxide and reductive bleach, disulfite, sulfite and borohydride, which are commonly used in mechanical and chemical pulp bleaching.
Main products of washing and bleaching:
Spray pot, medium consistency pump, vacuum drum washer, twin roll press, sand remover, screw pulping machine, pulp storage tower, bleaching tower, black and white tank, matching pump valves, mixers, knots, etc.
Any washing equipment is mainly used in diffusion, filtration and extrusion, the rest of which is secondary, not just one function.