Recognition and Prevention of Scale Trouble in Papermaking Operation Focus on Barium Scale as Well as Calcium, Silicon and Aluminium Scale

The key aspect of minimizing the descent of quality and productivity in papermaking is to identify the origins of scale and to realize the appropriate treatment. Scale derived from calcium, silicon and aluminium is most commonly reckoned and easily collected. In the present study, we focus our attention on another serious situation of such adherent scale as barium sulfate, of which boil-out treatment by chemicals, either alkalization or acidification, has been found unavailing so far. A promising clue to inhibit the increase of barium scale would be the avoidance of derivation out of aluminium sulfate and sul furic acid. Since SO42exists in these two sources, an investigation on variation between the two different induction lines was performed. Here we found that these two induction lines were similar in the developing amount of barium sulfate scale, while the mechanism of each scale film might be different. The induction of barium sulfate on the surface of the walls and the pipes of wet end processes was more in the line of sulfuric acid than of aluminium sulfate. The present results indicate that the restriction of the use of sulfuric acid is one of the relevant approaches to solve the barium scale problems.