Effective Flotation Deinking of ONP with Increasing Levels of Flexographic Print, 1996 Pulping Conference Proceedings

Irenee J. Philippe

Allied Colloids Incorporated

The deinking of old news papers (ONP) has been practiced for several decades and conventional methods for deinking ONP are well established. Within the past decade a printing technology known as flexography has become popular and is presenting new challenges to the deinking of ONP. Flexographic printing inks are not effectively removed by traditional flotation deinking technology. Wash deinking processes can effectively remove flexographic inks. However, the resulting wash effluent, laden with flexo ink, is resistant to conventional clarification technology. Regardless the deinking method, increasing flexographic print content results in loss of deinking efficiency and lower deinked pulp brightness. A novel flotation deinking technology has been developed for the deinking of ONP with flexographic content. The details of this new technology, the results of flotation deinking with increasing flexographic content and the impact on deink clarification are discussed.