Neutral Deinking of Mixed Office Waste in a Closed-Loop Process

Rhône-Poulenc has developed chemistry for deinking mixed office waste under neutral pH conditions in a closed-loop process. A successful pilot-scale evaluation was conducted at Voith Sulzer Papertechnology to test new surfactant formulations under these conditions. Comparisons were made with an alkaline control. Testing was completed on an affordable MOW pack comprising 65% white laser ledger and 35% colored mixed office waste. The colored component included ONP, OMG and unbleached brown bags. The total groundwood content was evaluated at 10%. The surfactant formulations tested produced high dirt removal efficiencies under neutral conditions using a single flotation stage system with P-Y bleaching and without dispersion or kneading. A final pulp having 30 ppm TAPPI Dirt and 83 GE Brightness was achieved. Significant ash reduction to less than 2% was achieved without sacrificing yield. In addition, physical properties of tear and burst were improved by using an enhanced surfactant formulation. Excellent deinking was achieved on a realistic mill furnish using a single flotation/single wash process. This trial clearly showed the performance and chemical cost reduction potential of neutral processing conditions.