Influence of Additives upon the Viscosity of Concentrated Deinking Waste

The literature survey reveals little information relating directly to deinking waste. This waste is composed mostly of coating and filling pigments such as clays and calcium carbonate therefore a study was made along these lines. Hauser (8), and other colloidal chemist, generally agree that clay and other pigment suspensions can be dispersed with certain chemical additives. This is said to be attributed to the active forces of repulsion between the particles which in turn produce a marked effect upon the flow properties. Further studies reveal that the Hercules Hi-Shear viscometer has been useful in analyzing high solids pigment suspensions which display non-Newtonian properties and during application are subjected to high rates of shear. An example of this is high solids coating colors as applied to a webb of paper at high machine speeds. A study of concentrated deinking waste from paper mills was made to find if solids content could be raised without increasing the viscosity. Many chemical additives were tried without marked effect. The high viscosity of deinking waste is due primarily to the small amount of fibers present. Removal of some of these fibers through wet screening, keeping the solids content constant, showed a marked drop in viscosity. Repeated washings of deinking waste indicated that it is already in a dispersed phase as received from the deinking mills. Analysis indicated that this is due to presence of sodium resinate