Online analysis of macrostickies in a sorted office waste recycling plant making tissue

An online macrocontaminant analyzer, the FPAutoSpeck, was used for 8000 measurements of deinked pulp to determine the number and area of heavy stickies, light macrocontaminants, and dirt. The analyzer detected a wide range of macrocontaminant levels, during which the three types of macrocontaminants varied independently of each other. “Stickies storm” levels were detected and visualized by the analyzer, with heavy stickies levels exceeding 17000/kg in the final pulp. Different particle size distribution patterns were noted for the light macrocontaminants when compared to those obtained for heavy stickies and dirt. Mill surveys of the fine screens and flotation cell showed different removal efficiencies for heavy stickies and light macrocontaminants. Fine screening was slightly more efficient in the removal of heavy stickies than of light macrocontaminants. Fine screens were more efficient at removing heavy stickies with particle sizes larger than 400 μm in diameter. On the other hand, flotation could remove heavy stickies with particle sizes of 200-300 μm. Furthermore, flotation was able to remove most of the light macrocontaminants independent of their particle size.