Processing waste paper

摘要

In the processing of waste paper containing a high proportion of dyed and/or wood-containing papers, the usual steps of disintegration, dye particle separation and flotation are followed by a multi-stage bleaching process. The first stage uses a hypochlorite bleach, whilst the second employs sodium hyposulphite or hydrogen peroxide. Preferably, the second stage employs sodium hyposulphite and a third stage hydrogen peroxide.