CHARACTERIZING INK DISPERSION IN NEWSPRINT DEINKING OPERATIONS USING SPECIFIC EDGE LOAD

摘要

Disc dispersers are used in paper recycling operations to detach recalcitrant ink from fibre and comminute ink particles to below a visible detection limit of 50 microns. A laboratory 30 cm Sprout-Waldron refiner with pyramidal plates was used to study the dispersion of old newsprint (ONP) at suspension mass concentrations of 10, 20 and 30%, rotor speeds of 1750 and 2500 rpm and gap widths of 0.05, 1 and 2 mm. Dispersion efficiency was measured using the effective residual ink concentration (ERIC) of unwashed and hyper-washed pulp samples with the disperser characterized using the specific energy and specific edge load (SEL). At 2500 rpm, the ERIC of hyper-washed pulp decreased as energy consumption increased to 40 kWh/tonne. At 1750 rpm, ERIC decreased at a slower rate and did not reach the same level. This was attributed to a reduction in dispersion intensity, which dropped from 0.16 W·s/m at 2500 rpm to 0.08 W·s/m at 1750 rpm.