THIOUREA DIOXIDE BLEACHING OF RECYCLED OLD NEWSPAPERS

摘要

The effects of the three main process variables (time, temperature and thiourea dioxide charge) on thiourea dioxide (TD) bleaching of pulp from recycled old newspapers (ONP) were studied in this paper. The results showed that the optimum conditions for TD bleaching were: reaction time 20 -30minutes, temperature 70°C and TD charge 0.7% (based on the weight of o.d. pulp). Under these conditions, a brightness gain of about 5 ISO points was obtained. The basic cost of this technology was about 130 yuan per ton pulp.