Mill-scale optimisation of an oxygen stage for bleaching MOW, Part II

The de-inking plant at the Kilbagie Mill of Inveresk is producing pulp with a brightness of ISO 87-90 and a dirt count of 5ppm or less. It enables the mill to make P&W grades which are virtually indistinguishable from virgin paper, although made from a much cheaper, MOW furnish. This paper describes how Kilbagie Mill's oxygen-based bleaching system was optimised to control problem contaminants such as: dyes, brown unbleached fibre, wet strength resins, groundwood, stickles and speck dirt. The system is very cost effective in chemical usage, bringing savings of $200k to $300k a year compared with a peroxide system.