ASAM PULPING OF EUCALYPTUS-CAMALDULENSIS AND TCF BLEACHING OF THE RESULTING PULPS

Wood chips of E. camaldulensis were delignified using both the ASAM (A lkaline Sulfite Pulping with Anthraquinone and Methanol) and the kraft process. In the case of ASAM pulping various modifications were teste d; ASAM I with NaOH, ASAM II with Na2CO3 addition and PH ASAM with a m ild prehydrolysis. The pulps obtained were subsequently TCF bleached ( OZP). Conventional bleaching (CED, CEDED) was performed as reference. The ASAM and kraft pulping yielded comparable delignification results. The strengths of unbleached and bleached ASAM pulps were approximatel y 20% higher than those of the kraft pulps. ASAM I pulping results in better delignification, selectivity and pulp strength than ASAM II pul ping. Compared with the standard process, prehydrolysis ASAM (PH ASAM) gives even better results in delignification and selectivity. In TCF and conventional bleaching 90-91 and 87-89% ISO were reached, respecti vely. The kraft pulps required more bleaching chemicals than the ASAM pulps to reach 88% ISO brightness. Although TCF pulps show much lower viscosity, no substantial tensile strength differences were found betw een the conventionally and TCF bleached pulps, but conventional bleach ing leads to somewhat higher tear strength.