APPLICATION OF STRENGTH TECHNOLOGIES IN A WORLD OF DECLINING FURNISH QUALITY, 'LIGHTWEIGHTING', AND AN INCREASINGLY CROWDED WET END

摘要

A variety of market forces have combined over the last decade or so that have resulted in declining "OCC" quality, increased ash levels, and a desire to maintain strength properties at lower and lower grammages. For those producers with integrated pulp mills the pressure to increase throughput with existing assets has resulted in increased carryover in many cases with complicating effects on wet end chemistry. To further complicate matters many mills have found it necessary to reduce overall fresh water usage, further "closing" the wet end with it's resulting cycle up in concentration of dissolved, and filterable materials. Use of dry strength additives has been increasing as has the number of options available and the complexity of the programs. The days of 4-6 kg/t of cationic starch in the wet end as the "strength" program are largely gone. Today's "strength" programs are often some combination of cationic starch, cationic resins, anionic resins, amphoteric resins, retention & drainage polymers, and enzymes. Combined dosages of some of these programs can top 30kg/t. Designing the right program for a given machine and grades, getting everything to "play nice" together and deliver the desired strength properties and overall total cost reduction can be a real challenge. In this presentation we'll explore what we feel are some of the more effective chemical technologies, application technologies, and program design methodology for delivering cost effective results.