Study On The Chemical Neutral Deinking Technology Of Office Wastepaper

In the past 20 years, The technologies of deinking and recycling wastepaper have been improved quickly, more and more second fiber is being used year after year. It is well-known that the quality of office wastepaper is better than that of the others, and it's difficult to deink this kind of ink using conventional alkalinemethods. So a new deinking method-neutral deinking method is being usedto remove office waste paper ink in this thesis.The first part of this paper: a new kind of deinking agent-GW01 neutral deinking agent was used to deink electrostatic-printed paper by changing deinking technological conditions (deinking agent dosage, pulping time, pulping consistency, pulping time, heat-preserved time, floating time, etc), and the best technological conditions were found, as follows:Pulping time:30min;pulping consistency: 10%~ 12%; pulping temperature:60癈; heat-preserved time: 20min; floating time: 10min; floating consistency: 0.8%; floating temperature: 50℃. Electrostatic-printed paper was deinked by using neutral deinking agent and two kinds of alkaline deinking agents under each given conditions. The results showed that brightness and ink-removed percentage of the neutral deinking method was as much as that of alkaline deinking method, but waste water's COD of neutral deinking is lower than that of alkaline.The second part of this paper: the best deinking technological conditions of laser-printed paper were found by changing deinking conditions under neutral conditions, as follows:Pulping time: 25min; pulping consistency:10%~12%;pulping temperature:60℃; heat-preserved time: 20min; floating time: lOmin; floating consistency: 0.8%; floating temperature: 50℃. Under these conditions, the neutral deinking agent was used to deink laser-printed waste paper, and two kinds of alkaline deinking agents were used to deink laser-printed paper under given conditions. The results showed that neutral deinking has more advantages in waste water's COD and deinking costs than alkaline deinking.Under neutral conditions, the chemical deinking of electrostatic-printed paper and laser-printed paper can be done by using proper deinking agent and deinking conditions.