OCC plants convert recycled old corrugated containers into pulp that can be used on paper and board machines to make valuable pulp and paper products. After repulping, the OCC pulp contains some contaminants, such as staples, glass debris, and sand, as well as fiber flakes and bundles that were not separated into individual fibers during repulping. To remove these undesirable materials, the pulp slurry goes through one or more screening processes to remove the contaminants that are larger than fibers, followed by one or more cleaning processes to remove smaller contaminants that have lower or higher densities than pulp fibers. This course describes this cleaning process, the principles involved, as well as the safety hazards and guidelines associated with the OCC cleaning process.
Learning Objectives
At the end of this module, you will be able to:
- Describe the purpose of centrifugal cleaners at OCC plants
- Explain why low consistency cleaner efficiencies tend to be higher than medium and high consistency cleaner efficiencies
- Explain the principles involved in forward and reverse cleaning
- Describe process flows in forward and reverse cleaners
- Explain why multiple stage cleaning systems are used
- List safety hazards and guidelines associated with centrifugal cleaner systems