DEINKING IN TISSUE DEINKING LINES, 2010 TAPPI PEERS Conference

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The share of recycled fibres in the fibre supply for tissue papers is increasing. A decrease in deinking cost while maintaining present final pulp quality parameters and decrease in generated losses are required if its use is to be continued in tissue papermaking. A considerable variety of recovered paper grades are encountered in the production of deinked pulp for tissue, from mixture of newspapers and magazines to wood free grades of diverse qualities. From these heterogeneous raw materials, the deinking process needs to remove the various contaminants that are encountered including ink particles, mineral fillers and adhesives. Even if most of the deinking processes include screening, flotation and washing stages for the production of deinked pulp for tissue production, the order or the combination of the various steps can vary from mill to mill. Due to this heterogeneity in raw material quality and process implemented, a systematic study has been conducted in order to help deinkers in their choice of process configuration, raw material supply and running parameters to be implemented. A part of this work will be presented in the present paper and will include: (i) the potential of recovered paper grades according to pulping parameters, (ii) the influence of 1st deinking loop configuration on the overall process, i.e. the incidence of various 1st deinking loop options on the dispersing stage and also the incidence of these two steps on the efficiency of a 2nd loop and finally (iii) the development of a simulation platform. Some practical examples such as raw material composition in the mixture or the choice of implementing flotation stage in a first or a second loop are presented. This platform validated at pilot scale, is a very powerful tool to determine both the final ink content, the final speck contamination but also the process yield thanks to the knowledge of fragmentation and removal coefficients of each particles types including mineral filler and fines elements for the various recovered paper grades. Even if this simulation platform was defined from experiments performed with pilot devices, the methodology used is directly applicable to paper mills