Bleached Fiber from OCC by the NACO Process, 1994 Recycling Symposium Proceedings

Michael Jackson, Ingemar Croon, Franco Nardi

Current deinking processes have limited capabilities to produce high quality fiber from available recycle grades and require high cost upgraded raw material. Alternative routes to the production of recycle fiber that can be included in high quality papers are of high interest.

A process which converts old corrugated containers (OCC) to high quality bleached fiber suitable for use in printing and writing paper production has been in operation in Italy for several years.

The process, termed the NACO pulping process, has been described in European and North American patents (1, 2 and 3). Fiber raw material is treated in a preliminary repulping and cleaning stage, then subjected to an oxygen alkaline treatment in a unique medium low consistency reactor.

Repulped OCC typically has an 85-105 kappa level. The process delignifies the pulp to the 15-25 kappa range. Various bleach sequences have been applied to the pulp including P, ZP and HH. Brightness levels of 75-80 are reached. Alternative ECF sequences such as DED could be applied but have not been operated on a commercial basis.

The process has been in operation at the Foggia and Crotone mills of Istituto Poligratico e Zecca della Stato in Italy since the mid 1980s. The pulp produced is used in printing and writing and security papers and is sold as market pulp.

The process is also used in these mills to produce straw and high quality cotton linters pulp in non-sulfur, non-chlorine systems.