Use of Colloidal Gas Aphrons for Separation of Water Based Printing Inks and Impurities from Paper Stock Suspensions, 2010 TAPPI PEERS Conference

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Recovered paper is the most important fiber resource in the German paper industry. The utilization rate adds up to 71 % in 2009[1]. An important component of the impurities in recovered paper is printing ink. The removal of water based printing inks, which today are often used in the flexographic or inkjet printing, turns out to be a big problem. The problematic removal by flotation is not only based on their dimension but also on their hydrophilic behavior. Unlike this, the usage of water based printing inks in printing processes increases due to economical and ecological advantages caused by the simple application and cost savings.

The aim is the development of a new flotation technique which could remove these particles. It is analyzed if foam generated by an invention of Sebba during the 1970s, named colloidal gas aphrons (CGA), could be used in such a way.

The CGA are created by a rotating disk in a container with special baffles included. The disk rotates with high revolutions and the air in the boundary layer above the liquid is sucked in. By discovering suitable parameters for a new continuously running flotation apparatus, generating CGA and flotation are performed in separate processes.