Reconciliation Methods for Yield Loss and Moisture Distortion in Reclaimed Paper Ledgers
Reconciling reclaimed paper ledgers requires converting scale intake weights to bone-dry fiber mass using core probe testing per ISO 287.
Fines Depletion
Fiber Composition
Small fiber fragments and mineral particles often pass through the forming fabric of a paper machine during the initial stages of drainage. This fines depletion occurs when the vacuum and gravity forces pull the smallest elements away from the mat of larger fibers. It results in a sheet with different properties on the top side compared to the wire side.
Machine Performance
Changes in the retention of these small particles affect the porosity and smoothness of the final paper. If the fines depletion is excessive, the sheet may lack the necessary internal bond strength for demanding printing processes. Excessive loss also increases the load on the water clarification system.
Drainage Management
Chemical additives are used to flocculate the small particles and attach them to the longer fibers to reduce the impact of this loss. Monitoring fines depletion allows the operator to adjust the dosage of retention aids in real time. This control is vital for maintaining a consistent ash content and ensuring the sheet meets the opacity specifications.
Consistent retention prevents the build-up of solids in the machine white water circuit which reduces the need for frequent cleaning. Proper management of these small particles also improves the efficiency of the press section by creating a more uniform sheet structure.