Fibre Separation Efficiency
Chemical residue and adhesive loads define the mass fraction of non-dispersible debris collected during the laboratory disintegration of paper substrates. This repulpability reject percentage determines the throughput capacity of screening equipment in a secondary fibre recovery facility. Measurements reflect the weight of screen rejects relative to the initial dry mass of the processed sample under controlled aqueous conditions.
Contaminant Assessment Metrics
High levels of moisture-set inks or heavy coatings force substantial increases in the volume of material captured on coarse screens. Mills set threshold limits for this value to prevent the saturation of deinking systems and to maintain the purity of the final pulp slurry. Laboratory testing uses a standardized disintegrator to mimic pulping action before the contents pass through a slotted screen plate.
Operators weigh the resulting dry reject fraction to calculate the ratio against the starting input. Variability in this result signals shifts in the quality of the incoming feedstock or the efficacy of chemical additives designed to break down sizing agents. Consistent monitoring prevents the accumulation of sticky contaminants that otherwise foul fine screen apertures and paper machine wires.
Process Operational Constraints
Production targets rely upon low reject fractions to minimize the loss of viable cellulose fibres during the clarification stage. Secondary pulp mills require this ratio to remain below specific thresholds to ensure the economic feasibility of the recycling cycle. Low repulpability reject percentage values directly correlate with higher yield rates and reduced waste disposal volumes for paper converting facilities.
