Recycled Fibre and Deinking

Transcription

1 Papermaking Science and Technology a book series covering the latest technology and future trends Book 7 Recycled Fibre and Deinking Second Edition Totally updated version Book editors Höke, Ulrich, Dr.-Ing., Chairman of INGEDE (International Association of Deinking Industry) and Managing Director of Stora Enso Sachsen Mill and Schabel, Samuel, Prof. Dr.-Ing., TU Darmstadt, Head of the Department Paper Technology and Mechanical Process Engineering (PMV) Publisher Paper Engineers Association/Paperi ja Puu Oy Paperi ja Puu Oy

2 Table of Contents 1 Recovered paper statistics and definitions Legislation Collection systems, sources, sorting, quality and storage of recovered paper Recyclability of paper and board products Unit operations and equipment in recycled fibre processing Design of recycled fibre processes for different paper and board grades Additives Papermaking potential of recycled fibre Measuring and test methods Final disposal of waste from recycled fibre-based papermaking and of non-recycled paper products Annex Glossary Index

3 CHAPTER 1 Recovered paper statistics and definitions 1 General Grade classification and definitions Recovered paper classification in Europe Recovered paper classification in the United States Recovered paper classification in other regions Recovered paper terminology and definitions in Europe Paper and board recycling chain Statistics General Recovered paper collection Recovered paper utilisation Europe recovered paper and other fibres Use of recovered paper in different paper grades in Europe Global recovered paper trade flows...22 References

4 CHAPTER 2 Legislation 1 New EU Waste Directive a valuable tool for paper recycling Tasks for EU member states Key points for the paper industry Complementary actions and voluntary commitments by the industry European Declaration on Paper Recycling Guidelines on responsible sourcing and quality control REACH and paper recycling REACH Regulation Recovered substances and REACH Information: requirements and possibilities under REACH Residues from paper recycling, Landfill Directive and prevention Packaging and packaging waste directive Waste Shipment Regulation Recycling and food contact legislation...37 References

5 CHAPTER 3 Collection systems, sources, sorting, quality and storage of recovered paper 1 Introduction Collection systems and equipment Pre-consumer recovered paper Post-consumer recovered paper Pick-up systems Drop-off systems Efficiency of different collection systems Sources of recovered paper Fibre flow in Western Europe Recovered paper potential Sorting of recovered paper Manual sorting Automatic sorting Preliminary coarse separation Further automation by fine separation Handling of recovered paper Loose recovered paper Baled recovered paper Shredding of filed paper Guidelines for responsible sourcing Quality characteristics of recovered paper Prerequisites for quality control Moisture content Ash content and Schopper-Riegler value Composition and other characteristics Brown grades White grades Storage of recovered paper...82 References

6 CHAPTER 4 Recyclability of paper and board products 1 General aspects of recyclability Technical aspects of recyclability Non-paper components in recovered paper Repulpability Removability of unwanted material Inks and toners Adhesive applications Suitability for contact with foodstuffs Deinkability Deinkability of different printed products Deinkability by printing technology Offset prints Rotogravure prints Waterbased flexographic newspapers Toner prints Inkjet prints Solid ink prints Removability of adhesive applications References

7 CHAPTER 5 Unit operations and equipment in recycled fibre processing 1 General overview Fluid mechanics of pulp suspensions Introduction to the rheological effects and handling of fibre suspensions Evaluation and modelling of separation processes General overview of unit operations Slushing and repulping Basics Machinery HC and MC pulpers LC pulpers Drum pulpers Deflaking Objectives and system integration Physical principles Machinery Screening Objectives and system integration Physical principles Barrier and probability screening Basic screening machine designs Basic physical mechanisms in pressure screens Passage of fibres through apertures Cleaning of screen baskets by flushing back or shear forces Rejecting contaminants Modelling pressure screens and screening systems Modelling of single pressure screens Modelling of screening systems

8 Unit operations and equipment in recycled fibre processing 7.6 Machinery and design variations Coarse screening Fine Screening Screening results Individual machines Screening systems Screening deficiency Thickening Deflaking Separation in centrifugal field Objectives and system integration Basic physical principles Effects of design parameters Operation modes Machinery and operation HC cleaners MC cleaners LC Cleaners Cleaner systems Final-stage cleaners Centrifugal cleaners with rotating housing (centrifuges) Abrasion Fibre fractionation Reasons and objectives for fibre fractionation Equipment and processes for fibre fractionation Fractionation equipment available at industrial scale Fractionation equipment available at pilot scale Flotation Objectives and system integration Selective flotation Principles Prerequisites for good deinking results Flotation process Probability mechanism Quantity and size of bubbles

9 CHAPTER Collision between bubbles and particles Attachment Stable transport Bubble formation and motion Bubble generation Relative velocity Typical operating conditions Flotation cells and their operating principles Characteristics of different deinking flotation cells Deinking flotation cells on the market Foam deaeration Main quality criteria for deinked pulp Laboratory cells Total flotation Prerequisites for good water purification Characteristics of different dissolved air flotation devices New developments in deinking technology Combination of flotation deinking with advanced washing technology Optimisation for flotation of water-based printing inks and water purification Dewatering Objectives and system integration Principles Machinery and effects Belt and drum filters Disc filters Screw press Other kinds of dewatering machinery Washing Objectives and system integration Principles Machinery Belt filter type machines Disc thickeners Spray filters Pressure screen type washers

10 Unit operations and equipment in recycled fibre processing 13 Dispersion and kneading Objectives and system integration Physical principles High-speed dispersing Low-speed kneading Machinery and operation Disc dispergers Conical dispergers Kneaders Performance of dispergers and kneaders Refining Objectives and system integration Physical principles LC refining HC refining Machinery and design versions LC refining HC refining Refiner performance Refining of recycled fibre pulp for packaging papers Refining of recycled-fibre pulp for printing and writing papers Change in values on refining Mixing and storing Objectives Principles Mixing Storing and prevention of demixing Machinery Mixing Storing and prevention of demixing Preventing entanglement of impurities Storing suspensions with high stock consistency Acknowledgements References

11 CHAPTER 6 Design of recycled fibre processes for different paper and board grades 1 Introduction Design principles Efficiency and costs Methodology of stock preparation process design Initial design concept development Design engineering Modelling and simulation Balances Software tools Optimisation Grade-specific process design Printing and writing grades Process for newsprint, SC and LWC grades Market deinked pulp Tissue Packaging paper grades Testliner Corrugating medium Board grades Water and reject management Reject and sludge treatment Water management Evaluating the cost-effectiveness of process layout options Technical aspects to be covered in the evaluation Evaluation of process layout options for packaging papers References

12 CHAPTER 7 Additives 1 Deinking Chemicals Objective of deinking chemistry Method of ink removal Requirements for successful ink removal Chemistry for ink detachment Function of caustic soda Function of silicate Function of hydrogen peroxide Chemistry for ink removal by flotation Collector function Fatty acids Oleic acids Soap pellets Fatty acid and calcium soap emulsions Carryover of fatty acids / soaps Silicone derivatives Synthetic collectors / surfactants Choice of a suitable collector Chemistry for ink removal by washing Synthetic surfactants Further aspects Foam control in flotation units Bleaching of deinked pulp Importance of bleaching Wood-containing DIP Wood-free DIP Special aspects of DIP bleaching

13 Additives 2.2 Lignin-preserving bleaching Peroxide bleaching (P) Dithionite bleaching (Y) FAS bleaching (FAS) Combined bleaching stages Lignin-degrading bleaching Bleaching with chlorine-containing chemicals Bleaching with oxygen chemicals Fibre fractionation in DIP bleaching Other effects of bleaching OBA destruction Colour stripping Process water treatment Dissolved air flotation (DAF) Microflotation mechanism Chemical concepts of microflotation Principal design parameters of industrial plants Achievable clear water quality DAF system design Saveall (Filtration or sedimentation) Defoamers Biocides Special additives Stickies control Detackification by minerals Detackification by polymers Fixation Other options Enzymatic treatment of recycled fibres Upgrading of recycled fibres Enzymatic deinking Recerences

14 CHAPTER 8 Papermaking potential of recycled fibre 1 Differences between virgin and recycled fibre Introduction Effects of recycling on chemistry and morphology of fibres Hornification of fibres during drying and recycling Changes in fibre morphology and flexibility Effects of chemical conditions on flexibility of fibres Changes in surface chemistry of fibres Effects of recycling on pulp sheet properties Effects on strength properties in recycling Effects on other properties Validity of experimental simulations of paper recycling Design of recycling experiments Chemical conditions in recycling experiments Results of multiple recycling experiments Recycled fibre quality related to remaining contaminants and inks Classification of contaminants Techniques for removing contaminants Effects on RCF quality Effects of residual ink particles Effects of coloured fibres Effects of stickies Effect of fillers Effects of other detrimental substances Modelling of age distribution of RCF One-parameter model Multi-parameter model

15 Papermaking potential of recycled fibre 3 Recycled fibre in papermaking General aspects Downgrading and upgrading of recovered paper Downgrading Upgrading Effects of deinking process yield on pulp characteristics Losses of fines and mineral pigments in deinking process Fibre yield in deinking flotation Effect of flotation on strength properties Improving papermaking potential of RCF by mechanical treatment Effects of refining on mechanical fibres Effects of refining on deinked pulp Effect of refining on hornified chemical fibres Effect of chemical conditions on refining results Effect of elevated temperature on RCF during dispersing or refining Effect of high-consistency treatment on curl of RCF Effects of recycled pulp on paper machine wet-end chemistry Carryover of deinking chemicals Return of used wet-end chemicals back to papermaking Reduction of water consumption in RCF processes Characteristics of anionic trash derived from recycled pulps Chemical oxygen demand (COD) derived from recycled pulps Effects of dissolved inorganics in recycled pulps Removal of dissolved and colloidal material from recycled fibre circuits Runnability characteristics of deinked pulp Effect of DIP on dewatering in manufacture of printing grades Performance of recycled chemical pulp as reinforcement fibre Effects of growing use of RCF in high-quality of printing paper grades Effects of increasing recycling rate on quality of newsprint Deinked pulp in magazine paper grades Quality potential of RCF derived from office paper Challenges in manufacturing packaging grades from RCF furnishes Current and future trends Optimisation of refining for OCC pulps Challenges for strength properties of packaging grades References

16 CHAPTER 9 Measuring and test methods 1 Test methods and specifications Deinking test methods and deinkability assessment Optical parameters of deinked pulp Measurement of spectral reflectance and brightness Colour shade Effective residual ink concentration (ERIC) Particle measurement by image analysis Yield of deinking processes Assessment of print product recyclability Assessment of deinkability Early approaches The five parameter model Deinkability scores Stickies test methods and assessment of stickies removal ability Macrostickies INGEDE Method TAPPI pick-up method INGEDE Method INGEDE Method Micro- and other small stickies PMV method Deposition propensity of adhesives in paper machine dryer section Stickies deposition tendency tests in wet conditions Other sticky test methods FINAT test method FTM TLMI Method INGEDE Method Assessment scheme for removability of adhesive applications

17 Measuring and test methods 4 Other methods to test and assess recyclability Determination of non-paper components PTS Method PTS-RH 021/ Entry inspection of recovered paper Entry inspection of sorted graphic paper for deinking Equipment for sampling Sampling of baled recovered paper Sampling of loose recovered paper References

18 CHAPTER 10 Final disposal of waste from recycled fibre-based papermaking and of non-recycled paper products 1 Categories of paper mill and household waste Use and final disposal of solid waste from recycled fibre-based papermaking Solid waste composition and characteristics Rejects Deinking sludges In-plant pre-treatment Dewatering Drying Energy recovery in internal and external combustion plants Grate combustion Fluidised bed combustion Multiple-hearth combustion Available combustion technologies Emissions Composition and use of ash Co-firing of sludges and rejects Composting and agricultural use Composting conditions Composting processes Compost applications Composting of rejects and sludges Agricultural use Use in other industries Cement production Brick production

19 Final disposal of waste from recycled fibre-based papermaking and of non-recycled paper products 2.6 Landfilling Types of landfill Landfill gas generation Leakage from landfill Landfill sealing systems Landfilling of waste from recovered paper processing plants New developments Wet oxidation processes Filler recovery from combustion ash Fermentation processes Hydrolysis processes Pyrolysis processes Production of cat litter and absorbent materials Use and final disposal of non-recycled paper products Landfilling of non-recycled paper in the disposal of MSW Composting of non-recycled paper as a component of household biowaste Incineration of non-recovered paper as a component of MSW Incineration of non-recycled paper Non-recycled paper as a biofuel Pre-treatment of recovered paper as a biofuel Emissions Waste water from recycled fibre-based papermaking and waste water treatment Characterisation of untreated waste water Waste water treatment Suspended solids removal Biological treatment Characterisation of treated waste water Closed water circuits Removal of calcium from process water Use of scaling inhibitors Controlled precipitation of calcium carbonate Future development References