Trends in Sweden for closed cycle recovery of TCF bleach filtrates in integrated kraft paper production

Current recycling processes typically incorporate aggressive washing stages to successfully remove flexographic, or flexo, inks. The yield losses associated with such washing stages are often economically uncacceptable. A goal for many old newsprint (ONP) deinking mills is to be able to efficiently deink ONP containing varying, moderate levels of flexo inks in the flotation deinking stage. Deinking systems utilizing only flotation cannot handle more than 3-5% flexo ONP content. This paper discusses two flexo flotation deinking trials utilizing a novel organoclay chemistry in a 30 tons/day continuous-process pilot plant. Flexo ONP content was 25% and 30% in each of the two trial runs. The trials were performed with closed thickener filtrate loops without process water clarification. Brightness exceeded 60 points at the end of the process that involved predispersion flotation, conventional dispersion peroxide bleaching postflotation, and thickening. Application : the organoclay chemistry is a viable technology for flexographic ink and ash removal in flotation-only deinking systems.