Mass Evaluation
Gravimetric reject determination evaluates the dry mass of rejected material fractions relative to total input during sheet formation and finishing operations. Laboratory scales measure conditioned samples drawn from sorting stations or web trim recovery lines to establish accurate mass balances across the pulp preparation circuit. Moisture content variations distort wet weight readings, so drying ovens must reduce samples to absolute bone dry status before final balance logging.
Paper mills enforce this protocol on heavy linerboard grades where excessive moisture retention masks true fibre loss and inflates apparent yield calculations. Process engineers use the resulting data to calibrate consistency regulators and optimize refining intensity before pulp reaches the wire section.
Batch Accounting
Sorting efficiency metrics track how much usable stock escapes into recycling streams during broke pulper processing. Technicians collect discrete samples from reject augers over fixed operational intervals to capture variability across different shift rotations. Calculating exact fibre recovery requires subtracting inorganic filler mass from total dry reject weight following high temperature ash testing.
Converter plants apply this method to specialty packaging substrates where expensive barrier coatings alter the standard ash profile of the base sheet. Tolerances on coated board production demand precise tracking of lost coating weight to maintain chemical usage limits and prevent excessive effluent loading.
Yield Verification
Financial reconciliation relies on dry mass accountability to settle disputes over raw material consumption between paper mills and converting plants. Commercial supply agreements specify exact allowable reject percentages for each board grade before purchasing penalties apply to the delivered tonnage. Laboratory technicians dry and weigh composite samples gathered from slitter winders to verify compliance with contractual yield limits established during initial trial runs.
Production managers review these cumulative mass logs to detect gradual mechanical wear in refiner tackle and screening equipment before product quality drifts outside acceptable customer limits.
