In Situ Precipitated Calcium Carbonate in the Presence of Pulp Fibers – A Beating Study

Abstract

The paper industry around the world is in search for new ways to decrease production costs. New approached with additives such as new developed In Situ precipitated paper fillers materials have the potential to reduce production cost and increase profit margins. In Situ precipitated calcium carbonate filler with 20.9% and 41.7% filler material was produced in a large-scale laboratory unit using a eucalyptus pulp fiber suspension with a 1.7% fiber solids content. Laboratory beating tests were performed with a Valley Beater and APFI Mill using pure eucalyptus pulp with no filler content as the based trial and the two-laboratory manufactured In Situ precipitated filler pulps. Valley Beater and PFI Mill laboratory beating machines show similar differences/trends for the breaking length, tear and burst index. EC-pulp with no filler has the highest strength for breaking length, tear and burst index. With increasing filler level breaking length, tear and burst index decrease. Filler containing pulp shows a decrease in beating time for the same beating level.  20 minutes for the Valley Beater and 15000 revolutions for the PFI mill show highest change in pulp fiber beating level sufficient for paper making operation. Valley Beater and PFI Mill laboratory equipment operate different and an exact comparison of the beating curves is not possible. Based on the amount of pulp fiber needed for experiments the Valley Beater for large amounts and the PFI mill for smaller amounts should be selected. The SEM pictographs of the Valley Beater and PFI Mill beating trials from 0 stage to the high beating stage at 80 minutes for the Valley beater and 60000 revolutions for the PFI Mill show similar results. No damage to the fibers is noticeable at the unbeaten level. With increasing beating level. At a magnification of 430 times the fiber structure shows an increasing dense fiber structure with less visible pores. Magnification of 2500 times reveals increasing damage to the fiber wall and fiber surface.