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.
Ash Fraction Loss
Material Reduction
Mineral components within a pulp or paper sample decrease during processing or testing due to thermal decomposition or mechanical washing. Monitoring ash fraction loss allows mill technicians to determine the retention efficiency of fillers like calcium carbonate or clay. This value defines the difference between the initial mineral loading and the amount remaining after a specific production stage.
Process Impact
Chemical reactions at high temperatures during incinerating test samples cause some carbonates to release carbon dioxide. If the furnace temperature exceeds certain limits, the resulting ash fraction loss skew results by suggesting a lower filler content than actually exists. Such deviations require the use of correction factors to account for the volatile portion of the minerals.
To avoid these errors, laboratories maintain strict control over the ramp rates of their ovens.
Economic Consequence
High rates of mineral drift during the drainage stage on a paper machine wire lead to increased costs and potential wastewater treatment issues. When ash fraction loss occurs in a recycling circuit, it represents a loss of usable material that must be replaced by expensive virgin fillers. Maintaining stable retention levels ensures that the final opacity and brightness of the sheet remain within the specified range for the order.
Without this stability, the mill faces higher chemical costs and more frequent adjustments to the headbox flow. High mineral loss also increases the abrasive nature of the white water system which shortens the life of the forming fabrics.