Survey of Deposits and Contaminants in Mills Using Recycled Fibre, 2003 Fall Technical Conference

Paprican, in collaboration with IPST, has conducted a survey on deposits and contaminants in mills using recycled fibre. The survey was sent out in October 2001 to 495 North American mills that use any type of recycled furnish, including old newsprint/magazine, mixed office waste, and old corrugated containers. Participants were asked to respond to questions concerning: mill processes and unit operations, type and impact of deposits, experience with control measures and their effectiveness, and mill tests to evaluate deposition propensity. Responses were received from 45 mills, including 9 newsprint; 10 fine paper, tissue and specialty grades; and 26 board mills. Analysis of responses revealed that the most common locations, physical appearance, and impact of deposits were similar for all types of mills. There was no evidence that seasonal effects played an important role in deposition. In all cases, one of the worst aggravating factors was a higher proportion of recycled fibre in the furnish. In newsprint mills, pH and temperature shock were also important contributing factors to increased deposition. Control measures were highly varied and, in many cases, mill specific. Relatively few mills conducted tests to measure stickies in pulp and, in general, there was no correlation between stickies count and deposition on the paper machine. Based on the results of the survey and on comments from respondents, several recommendations were made for future research.