Standard Accounting Mechanics for Recycled Polymer Traceability
Recycled polymer traceability relies on strict mass balance boundaries, physical yield reconciliations, and verified custody transfers across conversion steps.
Mechanical Recycling Losses
Meaning
Material inefficiency measures quantify the mass of polymer lost relative to raw input waste during sorting, washing, shredding and melt filtration. Across post-consumer plastic re-processing, mechanical recycling losses determine the net yield of re-usable resin pellets obtained from incoming bale feedstocks. Non-target polymers, organic contaminants, moisture and paper labels represent physical mass removed during initial processing steps.
Process scrap also accumulates at screen changers where continuous melt filters purge heavily contaminated polymer fractions. The metric applies to all physical re-processing steps and excludes chemical depolymerisation yields.
Scrap Generation
Automated optical sorters and sink-float tanks reject non-conforming plastic types alongside heavy dirt particles during initial size reduction. High contamination rates in incoming post-consumer bales increase mechanical recycling losses rapidly during wash plant operation. Process optimization relies on precise friction washing parameters to strip surface coatings without grinding usable polymer into unrecoverable fines.
Melt Filtration
Continuous screen changers discharge contaminated polymer melt to maintain constant barrel pressure during re-pelletisation. Fine mesh screens capture degraded polymer gels and microscopic aluminum fragments, resulting in continuous purge streams. High filter purge frequency increases mechanical recycling losses in proportion to the contamination level of the feed resin.
Yield Economics
Mass balance calculations compare raw bale weight against final packaged pellet weight to establish net operational efficiency. Unrecovered polymer fractions increase conversion costs per kilogram of saleable post-consumer resin. Process profitability drops sharply when scrap generation exceeds established tolerance thresholds.