10.2.1.1 Paper Mill Rejects
The amount of rejects produced during recovered paper processing and their com¬position depends largely on the recovered paper grades. Figure 10.6 shows the composition of a reject sample as a mixture of rejects from six paper mills produc¬ing newsprint. Pulper and drum pulper are used for slushing of the recovered paper (old newspapers and old magazines). The proportion of the reject fractions as dry solids was 4 to 6 % related to air-dried recovered paper.
Due to the high proportion of plastic materials the heating value of rejects is more than 20 GJ t–1 of dry substance. The use of rejects as an energy source such as secondary fuels for cement production can be limited by a rather high chlorine content. It can amount to 3 % by weight of rejects on a dry basis. Polyvinylchloride (PVC)-containing materials such as self-adhesive tapes, foil laminates, carrier han¬dles and PVC products thrown in error into recovered paper containers are the main sources of this chlorine content.