METHOD OF CELLULOSE PRODUCTION WITHOUT CHLORIDE CHEMICALS Russian patent published in 1999 - IPC

FIELD: production of cellulose without chloride chemicals, in particular, in ozone bleaching of cellulose. SUBSTANCE: method includes bleaching of cellulose to whiteness of at least 86 ISO without chlorine bleaching chemicals, with strength of produced cellulose remaining commercially acceptable. In treatment of cellulose containing heavy metals such as manganese, pulp is cooked and delignified to kapp number in the order of 14 or below. Pulp bleaching is carried out in process sequence beginning from one stage with regulation of pulp pH within 2-7 and continued with peroxide stage. One stage of process sequence includes: bleaching of pulp containing heavy metals, such as manganese with ozone; treatment of pulp for removal of metals without washing of pulp between process steps of ozone treatment and metal removal; and bleaching of pulp with ozone or oxygen including intercascade washing or thickening or both, between ozone and peroxide steps. EFFECT: bleaching of cellulose pulp without preliminary removal of heavy metals. 31 cl, 7 dwg, 1 tbl