UK Paper Utilizes On-Line Ink Particle Analysis for Their New Deinking System, 1997 Pulping Conference Proceedings

UK Paper is a mill located in the south east of England. In January 1996 a new deinking system that was designed to deink mixed office wastepaper for the production of high quality deinked pulp was started up. This deinked pulp is used in the manufacture of high quality printing and writing grades. This is a 3-loop system which incorporates two stages of dispersion, two stages of bleaching and three stages of flotation. Each loop incorporates its own dissolved air clarifier unit to clarify the water streams before reuse. The net effect is a very complex plant with many chemical and mechanical interfaces that need close on-line controls in order to minimize interactions.

The mill installed an on-line monitoring system which can measure the ink particle size data almost instantaneously. The system enables the mill to monitor ink particle size in three locations throughout the deinking system. The data produced includes ink particle concentration based on number of particles, ink particle concentration based upon total area of ink, and ink particle size distribution. This on-line system allows the mill to monitor the constantly changing nature of incoming wastepaper and the reaction of the various equipment modules to those changing conditions. This was extremely useful in the start-up and process optimization phases of the project. The mill is now operating at full production, and the on-line ink particle monitoring system is used to monitor and optimize the performance of the individual units and overall system. This gives benefits both in the operation of the system and in the improved quality of the deinked pulp produced.

This paper will describe the technical features of the on-line image analysis equipment, the locations where the units were installed in the deinking system, and the results and benefits that were achieved.