Yield Determination
Recycling operations measure the mass of dry material recovered from a given batch of incoming secondary fibre. The resulting dry fiber recovery yield represents the percentage of usable material obtained after removing moisture and fillers. This percentage defines the productivity of the recycling line and helps determine the raw material costs.
Processing Loss
Reject streams from cleaning and screening stages carry away some usable material along with the debris. When screens are clogged, dry fiber recovery yield decreases as longer fibres are diverted to the reject chute instead of proceeding to the paper machine. Improving the separation process allows the system to retain more fibre and reduces the volume of solid waste.
Quality Correlation
Incoming baled paper contains variable amounts of ash and moisture that do not contribute to the final product. A lower dry fiber recovery yield is common when processing heavily coated papers, which contain large quantities of inorganic fillers like clay or calcium carbonate. This relationship forces mills to adjust their procurement specifications depending on the target grade of paperboard.
Adjusting the stock preparation parameters can mitigate some of these losses, but the chemical nature of the coating layer remains a limiting factor.
