LAB SCALE FINE-FRACTIONATION OF DEINKED PULP AND PARTICLE MICROSCOPIC ANALYSIS

SUMMARY An attempt was made at lab-scale to further fractio nate the fines fraction into much smaller fractions and to the characterization of the different fines fractions using optical and infra-red microscopy. T he fines ‘sub-fractions’ were classified on 50 µm, 25 µm, and 11 µm wire openings using hand held sieves by following a ‘soft-hyperwashing’ procedure . This particular process involved spraying a fine jet of water on particles on a particular sieve. Th e particles were ‘soft-hyperwashed’ till the filtra te turbidity dropped to 15-18 FNU range. At this stage it was assumed that the filtrate is free from any suspended particles. Analysis of re-slushed pulp (5 0/50 ONP/OMG blend) revealed that 25-30 % of particles pass through 11 µm opening By using transmission and reflected optical microsc opy on well dispersed particles deposited on glass slides, it was found that ink remained on coating f lakes and such type of flakes were mostly not associated with cellulosic fines. IR microscopy (mi ddle range FTIR: 500 cm -1 ‐ 4000 cm -1 ) coupled with spectrum analysis confirmed the presence of in k resins on coloured particles.