On-Line Focused Beam Reflectance Measurements of Peo/Cofactor Induced Fines Flocculation and Fines Deposition on Fibres on a Pilot Paper Machine

The focused beam reflectance measurement (FBRM) technique was used to monitor fines flocculation and fines deposition on fibres in pilot paper-making trials for producing newsprint from thernioniechanical pull) (TMP), using poly(ethylene oxide)/cofactor (PEO/CF) as a retention aid system. The FBRM measures the real dimensions (expressed as chord length) and the numbers of pulp particles during machine operation. The data demonstrate that changes in the flocculation behaviour due to the changes in retention programs can be monitored by the FBRM probe installed in the pulp line after the polymer addition point and before the headbox. For instance, the addition of PEO/CF stopped instantly the increase in fines counts (1-10 mu m), observed without PEO. Increases in PEO dosage resulted in a further decrease in fines counts. As a result, the fines retention increased. FBRM measurements also provide information about the retention mechanism. From the changes in the counts in various chord length ranges one call conclude that adding PEO in creases the fines retention by a combination of fines deposition oil fibres and fines aggregation.