Operational Results of Neutral Deinking for Old Newsprint and Potential Application in Asia-Pacific Recycle Mills, 2005 Engineering, Pulping & Environmental Conference

Earlier work has shown the success of a 10 day sulphite based neutral deinking trial. The neutral deinking process has now been successfully introduced into several recycle mills. Evaluations of free ink content and lab scale studies show the potential of this technology for the Asia-Pacific Region. The objective of this paper is to document similarities and changes in plant operations by a survey of recycle plant processes and comparisons of mill data before and after conversion. The mill survey includes information on pH, brightness, ERIC (a measure of ink that impairs brightness), ink removal efficiency, water brightness of grey water, ash content, and solids loss at flotation. In addition, a review of approximately one year of ERIC and brightness values before and after conversion to neutral deinking is made for each mill. The results found all three mills were able to obtain similar ERIC values after flotation despite higher ink fragmentation going into flotation. Two of the three mills were able to reach or exceed their target brightness based on average mill data. The third mill averaged within one point of the target brightness and had a lower final ERIC value. Based on these three mills, it may be concluded that sulphite based neutral pulper chemistry is a potentially viable option for long-term operation under varied mill operating conditions.