Novel Application of Tappi T 277 to Determine Macro Stickies Disintegration and Agglomeration in the Recycle Process, 2000 Recycling Symposium Proceedings

Oliver Heise, Bangj Cao, Ph.D., Dr. Samuel Schabel --The TAPPI T 277 test method describes a procedure for determining heat-set area and number of macro stickies in a specified amount of pulp screened. The recycle process is a separation process which removes macro stickies with a high degree of efficiency. Traditionally fine slotted pressure screening and most recently evidence that in some cases flotation has been the key process modules in separating macro stickies from the recycled fiber. Often Stickies balance around these particular process modules do not add up, which leads to the hypothesis that disintegration or agglomeration of macro stickies is taking place in various types of process equipment. The TAPPI T 277 test method divides the macro stickies in ten classes according to size and the application of statistical mathematical tools yields the ability to calculate the disintegration or agglomeration probability of macro stickies thereby explaining unsatisfactory stickies balances. These calculated findings are of significance, for example, screening equipment could be designed to minimize shear forces on the viscoelastic stickies to remove them more efficiently. Analyzing flotation stickies balances utilizing the hypothesis test (t-test) will lead to a better understanding why in some cases flotation removes and in other cases it does not remove macro stickies.