Recovery Metric
The percentage of usable fibre extracted from a sample during a controlled disintegration test indicates the efficiency of the recycling process for a specific grade. Measuring the repulpability laboratory yield involves weighing the dry material before and after it is processed in a standard disintegrator. This figure accounts for the loss of fines, fillers and non fibre components that are washed away or screened out.
It provides a baseline for predicting how a material will behave in a full scale mill. Accurate data helps in the selection of chemical additives.
Extraction Method
A specific agitation time and water temperature are maintained to simulate the conditions of a pulping drum. During the calculation of the repulpability laboratory yield, the slurry is passed through a calibrated screen to separate the individual fibres from the unpulped flakes. This separation reveals if the coatings or adhesives are interfering with the breakdown of the board.
Grade Variance
Different substrates show wide ranges of results based on their chemical treatment. A high repulpability laboratory yield is typical for uncoated kraft, while heavily laminated boards show much lower values. This measurement allows converters to select barrier technologies that maximize the recovery of the original cellulose.
