Opportunities for FAS in Secondary Fiber Processing, 1994 Recycling Symposium Proceedings

John D. Kronis, Norbert Nimmerfroh

The versatility of formamidine sulfinic acid (FAS) for brightening and color stripping is demonstrated through examples of its application in a variety of manners and on a variety of furnish types. In FAS pulper applications on magazines and labels, or on business forms, brightness gains of 3% or 8% ISO, respectively, were observed following subsequent deinking. In another instance, results are presented showing that a chemical treatment alone in the pulper is not as effective for brightening as having the capability of ink removal. In a disperser application of FAS, an average brightness gain of 5.2% IS0 was observed providing an average 84.1% IS0 brightness compared to 1.7% IS0 brightness gain in the absence of FAS.

Two-stage bleaching P-FAS is briefly discussed in relation to the trend towards improved bleaching results from P-FAS over FAS-P as the wood-containing content of the furnish increases. Also, in a case of processing office paper, results indicate that using hydrogen peroxide as in a pulper application and FAS in post-bleaching is favored over both chemicals used sequentially in post-bleaching Examination of the color of filtrates from bleaching trials on colored paper comparing FAS, peroxide and hydrosulfite reveals a significant advantage of using FAS. Lastly, in a series of bleaching experiments with increasing amounts of colored paper content, brightnesses of 80% IS0 or more are achieved tith up to 30% colored paper content using FAS, or with up to 60-65% colored paper content using two-stage P-FAS.