Removal of Wax and Stickies from OCC by Froth Flotation, 2000 Recycling Symposium Proceedings

Mahendra R. Doshi, Jeffrey M. Dyer, Oliver U. Heise, Bangji Cao--The presence of wax and stickies in OCC used in recycling can compromise product strength, appearance, and cause operational problems during papermaking. Although recovered OCC is sorted to remove wax-coated corrugated (WCC) prior to delivery to the mill, a sufficient quantity to be of concern enters with the recycled furnish. This research examined the application of froth flotation for removal of wax and stickies from repulped OCC. Pilot plant trials were conducted in which a conventional OCC stock preparation process with and without flotation was simulated. Additional aggressive washing and water clarification were also provided. Three OCC furnishes, one from a paper stock dealer, and two from recycle board mills, were evaluated. The inclusion of flotation in the OCC stock preparation system significantly improved the removal of wax spots and extractable material from the furnish. The data indicate that flotation was more effective in removing wax and stickies than through-flow cleaners. A compact flotation system with 0.93 kg/Mg (2 lb/ton) surfactant addition improved the OCC pulp quality with regard to wax spots by 60% and did not negatively affect strength properties. Total flotation losses were 2-5%. Studies indicated that wax and stickies are effectively removed from OCC in a flotation stage provided they are detached from fiber. The use of flotation can be favorable due to the lower fiber loss, lower energy requirement and less water consumption compared to other contaminant removal processes such as washing and through-flow cleaning.