Benchmarking Laboratory Fiber Yield Assessment Methods for EcoModulation Fee Calculation
Laboratory fiber yield metrics depend on screen slot geometry and ash corrections, directly determining EPR eco-modulation fee surcharges on packaging.
Slot Width 0.15 Mm
Screening Aperture
Precise mechanical openings in pressure screens are used to filter out contaminants and oversized particles from a liquid pulp suspension. Engineers specify a slot width 0.15 mm as a fine-scale filtration standard used in the final stages of stock preparation. It is specifically designed to trap shives, stickies, scale, and plastic fragments that are too small for coarser screens but large enough to cause defects.
This dimension is a mandatory specification for mills producing coated fine paper or high-end packaging board.
Separation Efficiency
Separation efficiency depends on the ratio between the size of the slot and the diameter of the flexible fibres. When using a slot width 0.15 mm, the screen allows individual fibres to pass through by aligning them with the flow while blocking flatter or more rigid contaminants. The narrowness of the opening requires high-frequency rotors to prevent the screen from plugging or blinding.
This fine aperture is highly effective at removing micro-stickies that would otherwise cause web breaks on the paper machine or picking on a printing press. Operating at this level of precision increases the cleanliness of the pulp but may reduce the overall throughput of the system.
Visual Purity
Visual purity is the primary benefit of using such small screen openings. By maintaining a slot width 0.15 mm, the mill ensures that the surface of the finished sheet is free from the dark specks or lumps that interfere with high-resolution printing. This technical choice protects the downstream converting equipment from damage caused by hard debris.