Pitch deposition in a fine paper mill

The development of process conditions that minimize the risk of pitch deposits is an ongoing concern in all paper mills. Domtar has used a team approach involving mill, research and suppliers to ensure efficient, deposit-free operation of the papermachines. Innovative deposit analyses, wet-end chemistry surveys, pitch particle counts and pulp quality testing were carried out in order to understand pitch deposition. The importance of the presence of polymerized pitch in deposits and throughout the papermaking system surfaced through these studies. Pitch deposition can usually be resolved by the following actions: changes in wood storage management, revision of the existing pitch-control programs and addition of extra screening to the thick stock.