Recycling Old Telephone Directories - Deinking with A New Generation Laboratory Flotation Cell, 2000 Recycling Symposium Proceedings

Bangji Cao, Ph.D., Oliver Heise, Ulrike Tschirner, Ph.D., Shri Ramaswamy, Ph.D.--There are about 750,000 tons of old telephone directories (OTD) available each year for collection and recycling. Processing OTD requires knowledge of their recyclability. This investigation intends to provide basic information to recycle OTD and to gain operational experience on a new generation of laboratory flotation cell-Delta25 TM . It was found that OTD contains excellent fibers that are equal to or better than ONP (old newsprint). Deinking of OTD is similar to ONP, but requires higher water hardness due to higher ink concentration. The newly designed laboratory flotation cell shows excellent runnability and efficiency with the addition of an automatic foam skimmer. A brightness gain of 9.5 points was achieved with OTD. However, because of the yellow ink in OTD the maximum brightness achievable is only 46%. When incorporated in ONP/OMG (old magazines) furnish, brightness drops 1.4 points for each 10% increase of OTD. OTD does not respond to reductive bleaching, i.e., hydrosulfite and FAS bleaching. This is a result of the publisher’s switch from dyed yellow pages to printed yellow pages.