DOCSLIB.ORG

Fibre to Board

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Fibre to Board Fibre to board Fibre to board Today’s processes of separating fibre and making paper- compost and road-building material. Using the entire tree board take place in facilities characterised by capital is an important part of our ambition to carry out sustain- intensity, high production volumes and the application of able production. the latest techniques of materials handling, continuous production and process control. From timber to fibre – the pulping process In many cases, including the mills of Iggesund Paper- The timber logs which are delivered to the pulp mill are first board, the production of pulp and the manufacture of debarked, since bark does not contain fibre suitable for paperboard are carried out on the same site in a continu- pulp manufacture. Bark is removed by friction, as logs are ous integrated process, giving benefits in quality, efficiency tumbled together in a rotating drum. The bark is then used and economy. as a fuel within the mill or composted to create garden soil. Managed forests provide the primary source of cellulose The next process depends on the type of separation or fibre from wood varieties such as spruce, pine and birch. defibration process used. The fibre is separated by mechanical or chemical pulp- ing and the whiteness and purity may subsequently be Pulp manufacture improved by bleaching. Basically the choice is between long fibres (spruce and Processing on the paperboard machine starts with the pine) and short fibres (birch). The boardmaker optimises formation of a layer of entangled fibres on a moving wire sheet forming, appearance and performance properties or plastic mesh from which water is removed by drainage. with an appropriate choice and blend of fibres to meet the Further layers of pulp are usually combined in the wet state. needs of particular products. More water is subsequently removed by pressing and dry - ing. Paperboard is coated on-line or off the machine to improve the printing surface. Large diameter, full machine- width reels are produced by the machine. These reels are subsequently cut into smaller reels or sheeted, labelled, and wrapped prior to dispatch to the customer. The forestry cycle The virgin fibre for paperboard is derived from naturally occurring species such as spruce, pine and birch, which provide fibres with suitable characteristics. These species are supplied by managed forestry operations in Sweden and other parts of Europe. To maintain sustainable development, including the re- quirements for biological diversity, modern forest manage- ment makes use of several combined methods. Detailed planning is done at both a county and local level. Natural regeneration, planting and sowing are used. Biologically sensitive areas and old growth forests are protected ac- cording to the local conditions. Another important characteristic is that managed for- PLANTING 0-3 years estry is an integrated operation whereby wood for pulping HARVESTING CLEANING 30-50 years UK 3-15 years UK is harvested with wood for the timber industry. Thinnings, 80-120 years 3-30 years Sweden the smaller diameter trees taken from the forest at vari- Sweden ous stages to allow other trees room to mature, are used sawn timber to produce pulp. When mature trees are harvested, the thicker part of the trunk is used as sawn timber, and the pulpwood tapered top goes to the pulp mill. This ensures maximum use of the harvested timber. Making the best use of raw materials is a key principle THINNING pulpwood within Iggesund Paperboard. The trees supplied to the 15-30 years UK mills are transformed into paperboard – but also into the 30-80 years Sweden energy that drives the production process, heats nearby homes and dries sawn timber. Other end products are soil 26 Reference Manual | IGGESUND PAPERBOARD Fibre to board IGGESUND PAPERBOARD | Reference Manual 27 Fibre to board Mechanical pulp characteristics which the debarked logs are first converted into small flat This process gives a very high yield from the timber. The chips. These chips, with a moisture content of 25–30 %, presence of lignin has a number of implications – the fibre are forced between the rotating metal discs of a refining is hard and rigid and this gives the sheet a limited degree machine. The heat and water vapour generated soften the of consolidation, high bulk (low density), resilience, dimen- lignin so the fibres can be separated. The pulp is screened sional stability, and stiffness. and cleaned and fibre clumps are reprocessed. The presence of lignin and the limited degree of consoli- Mechanical pulping results in a very high yield. About dation would make a sheet made solely from mechanical 95 % of the wood is converted to fibre. Mechanical fibre pulp relatively weak. The pulp retains the colour of the separation requires high levels of electric power, and some wood used and is of known natural composition and purity. of the energy is usually recovered and used as heat in the Refiner mechanical pulp (RMP) is a two-stage process in process. Washing Logs Chipping + of raw De- and Refiner barking defibration Bleaching Pulp to material washing board mill Bark for fuel or compost CONVEYORS Metering EXCESS CHIPS Screw RECIRCULATE WOOD Conveyors CHIP Preheater Preheater Preheater SILO REFINER CHIP WASHER AND DEWATERER BLEACHING REFINED FIBRE To screens and cleaners 28 Reference Manual | IGGESUND PAPERBOARD Fibre to board Chemical pulp characteristics solve 80–90 % of the lignin, allowing the fibres to separate This process preserves fibre length and the pure cellulose easily. develops a high degree of consolidation, both features that The sulphate process, which is used within Iggesund, give a very strong sheet. also permits efficient chemical recovery and energy utilisa- The fibre is flexible and soft, giving good creasing, emboss- tion. The fibre yield of unbleached chemical pulp relative to ing, and cutting properties and with low dust generation. wood is in the range of 50–65 %. The dissolved lignin and Bleached cellulose pulp has high whiteness, brightness, resins from the wood are used in internal energy generation. and light stability. This material has the highest purity and provides products with the best odour and taint neutrality. In the chemical process timber is first converted into wood chips. These are then cooked in chemical solutions to dis- Washing Logs Chipping Washing Oxygen De- Impreg- Continuous Diffusion + of raw and and delignifi- barking nation cooking bleaching Pulp to material washing straining cation board mill Chemical Bark recovery for energy fuel generation DEFIBRATION CHIPS O2 NaOH Modified continuous Pressure Double Oxygen delignification Final wash cooking diffuser wash straining PULP CIO2 CIO2 O2 NaOHH2O2 CIO2 CIO2 DIFFUSER BLEACHING IGGESUND PAPERBOARD | Reference Manual 29 Fibre to board Caustic soda/ High pressure steam sodium sulphide solution (white liquor) Chips + liquor IMPREGNATOR DIGESTER Chips Forward flow cooking Caustic Reverse soda/ flow sodium cooking sulphide solution (white liquor) Black liquor in recycle loop Wash liquor Impregnated chips Pulp (incl. liquor) 30 Reference Manual | IGGESUND PAPERBOARD Fibre to board Bleaching All these factors have technical and economic implications, All the varieties of pulp used in the manufacture of paper- not least of which is their environmental significance. board can be bleached to influence colour and purity. Whitening methods fall into three categories: Chemical pulp is brown in colour, the colour density • Bleaching by delignification using chlorine gas. This depending on the cooking process and degree of lignin approach has largely been replaced by processes with removal. While unbleached pulp may be used for some better environmental safeguards. The use of oxygen is purposes, such as corrugated board boxes, it is neces- being progressively introduced instead. sary to whiten the pulp for many graphical and packaging • Bleaching by oxidation using materials such as chlorine applications. dioxide, hydrogen peroxide or sodium hypochlorite. The whitening of pulp is called bleaching, though the • Bleaching by reduction using materials such as sodium process can take many forms depending on a number bisulphite. of factors. These include the degree of colour change If the pulp mill is integrated with paperboard manufac- required, choice of chemicals, method of treatment and ture, the pulp is pumped to intermediate storage facilities. whether coloured compounds are removed (delignifica- If the pulp is sold to the open market it is dried in sheets tion) or merely changed in colour. or by fluffing and drying in hot air. Market pulp is baled for shipment. IGGESUND PAPERBOARD | Reference Manual 31 Fibre to board Pulp (stock) preparation steel surface. A wet paperboard web will adhere to the cyl- If the pulp is bought in bales it is first mixed by agitation in inder surface and be progressively dried while at the same water in a large vessel known as a hydrapulper. All pulp, time achieving a very smooth board surface. This cylinder including the pulp which comes straight from the pulp mill is known as an MG (machine glazing) or Yankee cylinder. without drying, is then treated in various ways to prepare it for use on the paperboard machine. The processed pulp Surface sizing is referred to as “stock”. The consolidation properties of A starch solution can be applied to the paperboard surface fibre can be improved by mechanical processing – refining to improve strength and anchor surface fibres firmly in the – which modifies the surface structure of the fibre. Swelling sheet. Within Iggesund Paperboard the baseboard is sur- in water expands the fibres’ surface area, thereby increas- face sized prior to being coated. When board is surface ing their strength and ability to consolidate. sized a starch-based solution is applied to both sides of Additives such as internal sizing can be used to increase the product: this improves surface strength and anchors the water repellency of fibres, and retention aids to increase the fibres to the sheet.
Load more

Recommended publications
  • Print. Sublimate. Done. Complete Textile Print System
    GRAND BY DESIGN Print. Sublimate. Done. COMPLETE TEXTILE PRINT SYSTEM. The Neo Series A revolutionary water-based, dye-sub printer with an on-board calender for permanent sublimation. Get all the details at: printerevolution.com The Neo Series Tap into the digital textile market with a turn-key commercial fabric printing solution. Everything You Need To Succeed In keeping with our mission to drive innovation, PrinterEvolution introduced the Neo Series to be an all-in-one solution for textile printing. The result? A dye-sublimation printer with an on-board sublimation unit. Ink Media options • Achieve a brilliant color gamut with super rich blacks, a • The Neo Series printers can print on standard digital heavy pigment load and excellent grayscale. textile fabrics and specialty materials, such as open weave and stretch. • The vibrant, environmentally friendly, water-based inks pass all OEKO-TEX® Standard 100 certifications. They • Our system easily prints on mesh and other open are produced in an ISO 9001 facility with strict quality weave fabrics without marking the backside with control all at a very competitive cost per print. “blow-by” ink. A specially designed trough is fitted with a sponge and ink pad that absorb any ink that • The Neo Series printers use a 1.5 liter ink system. passes through the fabric. • For stretchable fabrics Superior quality and low cost of operation like Lycra, spandex and other sports textiles, the • The Neo Series utilizes Epson DX Variable Drop heads Neo uses a cork-covered that produce drops of varying sizes and colors within a cylinder to spread and single image file, marrying the best combination of the hold the fabric in place, image quality that comes with small drop sizes and the maintaining perfect, productivity associated with large drop printing.
    [Show full text]
  • Future Directions in Calendering Research
    Preferred citation: T.C. Browne and R. H. Crotogino. Future Directions in Calendering Research. In The science of papermaking, Trans. of the XIIth Fund. Res. Symp. Oxford, 2001, (C.F. Baker, ed.), pp 1001–1036, FRC, Manchester, 2018. DOI: 10.15376/frc.2001.2.1001. FUTURE DIRECTIONS IN CALENDERING RESEARCH T.C. Browne and R.H. Crotogino Paprican Pointe-Claire, QC, Canada ABSTRACT Calendering is the papermaker’s last chance to reduce thickness variations along the length and width of the finished sheet, and to improve the sheet smoothness. A smoother sheet results in improved print quality, while more uniform thickness profiles improve the winding process. The calendering operation thus improves the quality of the finished product. In recent years there has been an increase in the loads, speeds and temperatures at which soft-nip calenders, whether on or off line, can be operated without mechanical failure of the cover; the result has been an improvement in the surface and printing properties achievable with mechanical printing grades of paper, and an increase in the production rates which can be sustained. As a result, these calen- ders have slowly replaced traditional machine calenders in new and retrofit installations. The best available design and trouble-shooting tools for modern machine calenders are based on empirical models, whose coefficients have not been related to fundamental paper or fibre properties. New furnishes therefore require experimental deter- mination of these coefficients, and extrapolation to new calender- ing conditions involves some risk. As well, there are no published models, empirical or otherwise, for the design and trouble- shooting of soft-nip calenders, an unfortunate state of affairs given the increased number of installations of these machines.
    [Show full text]
  • Basics of Kraft Pulping
    Lignin Wood is composed of many chemical components, primarily extractives, carbohydrates, and lignin, which are distributed nonuniformly as the result of anatomical structure. Lignin is derived from the Latin term lignum, which means wood.1 Anselme Payen (1838) was the first to recognize the composite nature of wood and referred to a carbon- rich substance as the “encrusting material” which embedded cellulose in the wood. Schulze (1865) later defined this encrusting material as lignin. Lignin has been described as a random, three-dimensional network polymer comprised of variously linked phenylpropane units.2 Lignin is the second most abundant biological material on the planet, exceeded only by cellulose and hemicellulose, and comprises 15-25% of the dry weight of woody plants. This macromolecule plays a vital role in providing mechanical support to bind plant fibers together. Lignin also decreases the permeation of water through the cell walls of the xylem, thereby playing an intricate role in the transport of water and nutrients. Finally, lignin plays an important function in a plant’s natural defense against degradation by impeding penetration of destructive enzymes through the cell wall. Although lignin is necessary to trees, it is undesirable in most chemical papermaking fibers and is removed by pulping and bleaching processes. 1.1.1 Biosynthesis Plant lignins can be broadly divided into three classes: softwood (gymnosperm), hardwood (angiosperm) and grass or annual plant (graminaceous) lignin.3 Three different phenylpropane units, or monolignols, are responsible for lignin biosynthesis.4 Guaiacyl lignin is composed principally of coniferyl alcohol units, while guaiacyl-syringyl lignin contains monomeric units from coniferyl and sinapyl alcohol.
    [Show full text]
  • Paper Technology Journal
    Paper Technology Journal World paper market: Quo vadis newsprint? News from the Divisions: Stock Preparation, Paper Machinery, Finishing and Service. A Scandinavian Success Story. Notable Startups. Orderbook Highlights. China, changing times in 3 the cradle of papermaking. Contents Foreword 1 Corporate News Highlights USA/Germany: Voith Appleton machine clothing. 55 Startups, orders on hand 2 Austria: World paper market The Andritz Group – partnering the Quo vadis newsprint? 5 pulp and paper industry 58 News from the Divisions Germany: Stock preparation: B+G Fördertechnik thirty years on 64 Membrane technology for the further close-up of paper mill water loops 14 Germany: Board and packaging Paper Machinery: pilot paper machine upgrade – Ortviken PM 4 – facing the future with tomorrow’s technology today 22 versatility 69 Paper Machinery: Latest generation of cylinder mould New names, new addresses formers – FloatLip former N, NO, S 28 Hunt & Moscrop: now Voith Sulzer Paper Machinery: Finishing Ltd., Manchester 72 Serang BM3/BM4 – the exemplary commissioning 30 Voith Sulzer Paper Technology: regional representation in Jakarta 72 Gap Former Technology: No. 26 DuoFormer CFD installation a success 37 Special awards for innovation and design Paper Machinery: New applications in multilayer Neusiedler Paper wins innovation technology 38 award with a revolutionary 3-layer headbox and NipcoFlex press 73 Paper Machinery: Brilliant Coating with JetFlow F – SPCI ’96 – impressive presence 73 data, facts, experience 44 Finishing: Advertisement of the year in Brazil 73 Econip – a new generation of deflection compensating rolls 48 China: Service: The changing origins of GR2 cover – next-generation paper – from hand-made performance leader 51 to machine-made 75 Cover picture: Ortviken – successfull start-up (see article on page 22).
    [Show full text]
  • White Paper on Sublimation Technologies Rel
    ATPCOLOR White paper on sublimation technologies Rel. 1.7 Different technologies for thesame purpose, whichis the best? 1) So called “traditional procedure” 2) Direct printing on fabric and sublimation subsequent on separate calender 3) Direct printing on fabric and sublimation subsequent in integrated system using hot air 4) Direct printing on fabric and sublimation subsequent in integrated system with contact calender Index Sublimation 3 Inks, Need to know 1 Washing 3 Inks, Need to know 2 Sublimation/Disperse 4 Inks, Need to know 2 temperature and humidity 5 Traditional Procedure 5 Advantages 5 Disadvantages 6 Risks during the printing phase/fixation 6 Direct printing on fabric, sublimation in separate calender 7 Advantages 7 Disadvantages 7 Risks during the printing phase/fixation 8 Direct printing on fabric and sublimation with hot air 8 Advantages 8 Disadvantages 9 Risks during the printing phase/fixation 9 Direct printing on fabric and sublimation, with contact calender 10 Advantages 10 Disadvantages 10 Risks during the printing phase/fixation 11 R.1.7 S E I ECHNOLOG T ON TI MA Sublimation I UBL Phase Transition S wikipedia.org/wiki/Sublimation ER ON P A P Using so-called “sublimatic inks”, inks that once The process requires a high chemical affinity E deposited on media (in most o cases paper), if between dye and polyester fiber and vice versa IT taken at high temperatures (200° C) because otherwise there would be a lack of pe- WH “sublimate” pass from solid to gaseous state netration, this explains why you can’t use without passing through the intermediate li- sublimatic inks for printing on other textile fi- quid state.
    [Show full text]
  • American Ft Forest & Paper 2QE5
    A 1 , i American Ft Forest & Paper 2QE5; Association , - May 6, 2015 Via Hand Delivery and by Email to iones.iim(a^epa.gov Administrator Gina McCarthy (1101A) Office of the Administrator Environmental Protection Agency 1200 Pennsylvania Avenue, N.W. Washington, DC 20460 Re: Reguest for Full Exemption of Four Pulping Chemicals from the TSCA Chemical Data Reporting Rule Reguirements Dear Administrator McCarthy: The American Forest & Paper Association (AF&PA) hereby petitions EPA to amend the Chemical Data Reporting rule (CDR), 40 C.F.R. Part 711, to exempt from all CDR requirements four pulping chemicals involved in the manufacture of paper and other pulp-based products. The four pulping chemicals are complex mixtures used in the kraft pulping process: • Sulfite Liquors and Cooking Liquors, white (CAS No. 68131-33-9) (white liquor) • Sulfite Liquors and Cooking Liquors, spent (CAS No. 66071-92-9) (black liquor) • Sulfite Liquors and Cooking Liquors, spent, oxidized (CAS No. 68514-09-0) (black liquor, oxidized) • Sulfite Liquors and Cooking Liquors, green (CAS No. 68131-30-6) (green liquor) Each of these substances is manufactured and recycled onsite in a continuous closed loop. EPA has an enormous amount of information about these pulping chemicals and little current interest in them, as their potential risks are well understood and adequately managed. 1101 K Street, N.W., Suite 700 • Was hington, D.C.20005 • (202) 463•2700 •afandpa.org May 6, 2015 Page 2 This petition first identifies the four pulping chemicals in greater detail and explains why the kraft chemical regeneration process has led to inflated production volumes for these pulping chemicals in CDR data.
    [Show full text]
  • A Dynamic Na/S Balance of a Kraft Pulp Mill
    A dynamic Na/S balance of a kraft pulp mill Modeling and simulation of a kraft pulp mill using WinGEMS En dynamisk Na/S balans av ett sulfatbruk Modellering och simulering av ett sulfatbruk i WinGEMS Per Andersson Faculty of Health, Science and Technology Department of Engineering and Chemical Science, Chemical Engineering, Karlstad University Master theisis, 30 credits Supervisors: Niklas Kvarnström (KAU), Maria Björk (Stora Enso), Rickard Wadsborn (Stora Enso) Examinat or: Lars Järnström (KAU) 2014 -01-08 Version : 2.0 Abstract The main scope of this thesis was to create a simulation model of a kraft pulp mill and produce a dynamic Na/S balance. The model was made in WinGEMS 5.3 and the method consisted of implementing a static Na/S balance from the mill and created a model that described this chemical balance. Input data from the mill was collected and implemented in the model. A number of different cases were simulated to predict the effects of different process changes over time, dynamic balances. The result from the static balance showed that the model can describes the mill case. The result from the dynamic simulation showed that the model can be used to predict the effect of process changes over shorter periods of time. Executive Summary In the kraft mill the chemical balance is of interest to minimize the production cost. Normally there is an excess of sulfur and low levels of sodium, compared to what the process requires. In the future, the pulp mill will most likely produce other products than just pulp. These new production processes will also most likely affect the sodium and sulfur balance and there is a need to be able to predict this change.
    [Show full text]
  • Paper Recycling Technology Detailed Part 1A
    Paper Recycling Technology and Science Dr. Richard A. Venditti Paper Science and Engineering Forest Biomaterials Department North Carolina State University Lecture: Paper recycling and technology course introduction and objectives Dr. Richard Venditti Faculty member in the Paper Science and Engineering Program in the Forest Biomaterials Department at North Carolina State University PhD in Chemical Engineering, BS in Pulp and Paper Science and Chemical Engineering Research areas: � Paper recycling � Utilization of forest/agricultural materials for new applications � Life cycle analysis Named a TAPPI Fellow in 2012 Relevant research projects: – The detection of adhesive contaminants – The changes in fibers upon recycling – Automatic sorting of recovered papers – Flotation deinking surfactants – Agglomeration deinking – Screening phenomena and pressure sensitive adhesives – Deposition of adhesive contaminants – Neural networks to control deinking operations – Sludge conversion to bio-ethanol and to bio- materials Course Outline The US Paper Recycling Industry Recovered Paper Grades and Contaminants Effect of Recycling on Fibers/Paper Unit Operations � Pulping, Cleaning, Screening, Washing, Flotation, Dispersion, Bleaching, ….. Image Analysis, Deinking Chemicals System Design Advanced/Additional Topics Course Activities Viewing of the Videos of Lectures � Base lectures by Venditti � Guest lectures from industry leaders Homework assignments Final Exam Critical Issues in Recycling: Going deeper into the recovered paper stream
    [Show full text]
  • Alkaline Pulping: Deadload Reduction Studies in Chemical Recovery System
    ALKALINE PULPING: DEADLOAD REDUCTION STUDIES IN CHEMICAL RECOVERY SYSTEM A Thesis Presented To The Academic Faculty By Yusup Chandra In Partial Fulfillments Of the Requirements for the Degree Master of Science in Paper Science Engineering School of Chemical & Biomolecular Engineering Georgia Institute of Technology November 8th, 2004 ALKALINE PULPING: DEADLOAD REDUCTION STUDIES IN CHEMICAL RECOVERY SYSTEM Approved by: Dr. Howard (Jeff) Empie, Advisor Dr. Yulin Deng Dr. Sujit Banerjee Date Approved: November 8th, 2004 ACKNOWLEDGMENT I would like to dedicate this thesis first and foremost to my parents, Azis and Rienni, who have given me all the love and support the years. I would like to thank IPST for this great opportunity to attend this Georgia Tech and to meet all of the wonderful people here. Dr. Empie thanks for introducing me to this new thesis topic and doing a great job. I know it has been difficult through this period of time, but we got through it. Dr. Banerjee and Dr. Deng thank you for taking the time out of your busy schedules. I appreciate all the assistance and advice I have received from everyone on the committee. Lastly, I would like to thank the people that made my stay here in Atlanta an exciting and memorable experience. Special thanks to Luis, Sheila, Daniel, Jacobo, Josh, and Trevor who made getting through the toughest times so much easier. iii TABLE OF CONTENTS Acknowledgment iii Table of Contents iv List of Tables vi List of Figures vii Summary viii Chapter 1 Introduction 1 1.1. Terms and Definitions 2 1.2.
    [Show full text]
  • Construction Health and Safety Manual: Pulp and Paper Mills
    PULP AND PAPER MILLS 33 PULP AND PAPER MILLS The two common forms of chemical pulping are 1) the dominant “alkaline” or “kraft” process, and Processes 2) the “acid pulping” or “sulphite” process. Acid pulping has generally declined but is still in use. The A number of processes, grouped by type as mechanical, digester liquor is a solution of sulphurous acid, H SO , chemical, and semi-chemical (or hybrid), are used in 2 3 mixed with lime (CaO) or other base (magnesium, the preparation of wood pulp. In 1990 (according to sodium, or ammonium) to form bisulphites. Lockwood’s Directory) the distribution of pulp mills in Ontario and Quebec was as follows: Mechanical processes produce the highest yield from the wood, but have high energy demands. Mechanical pulping Process Type generally incorporates thermal or chemical pre-softening Chemical Processes Semi-chemical Mechanical Total of the wood chips, resulting in lower energy requirements. Kraft Sulphite Some chemical processes include mechanical features. Ontario 94 2 15 30 The division is not distinct and is generally based on Quebec 10 8241 61 efficiency of production from dry wood. Figure 22.1: Number of pulp mills by type in Ontario and Quebec Figure 22.2 provides a flow diagram for a semi-chemical pulp mill. In chemical pulping, the wood chips are cooked, using heat and a chemical solution that depends on the type of Of the chemical processes , alkaline pulping – the kraft process being used. The lignin binder, a natural glue that or sulphite process – is the most common and is shown in holds the wood cells (fibres) together, is dissolved.
    [Show full text]
  • Conservation of Coated and Specialty Papers
    RELACT HISTORY, TECHNOLOGY, AND TREATMENT OF SPECIALTY PAPERS FOUND IN ARCHIVES, LIBRARIES AND MUSEUMS: TRACING AND PIGMENT-COATED PAPERS By Dianne van der Reyden (Revised from the following publications: Pigment-coated papers I & II: history and technology / van der Reyden, Dianne; Mosier, Erika; Baker, Mary , In: Triennial meeting (10th), Washington, DC, 22-27 August 1993: preprints / Paris: ICOM , 1993, and Effects of aging and solvent treatments on some properties of contemporary tracing papers / van der Reyden, Dianne; Hofmann, Christa; Baker, Mary, In: Journal of the American Institute for Conservation, 1993) ABSTRACT Museums, libraries, and archives contain large collections of pigment-coated and tracing papers. These papers are produced by specially formulated compositions and manufacturing procedures that make them particularly vulnerable to damage as well as reactive to solvents used in conservation treatments. In order to evaluate the effects of solvents on such papers, several research projects were designed to consider the variables of paper composition, properties, and aging, as well as type of solvent and technique of solvent application. This paper summarizes findings for materials characterization, degradative effects of aging, and some effects of solvents used for stain reduction, and humidification and flattening, of pigment-coated and modern tracing papers. Pigment-coated papers have been used, virtually since the beginning of papermaking history, for their special properties of gloss and brightness. These properties, however, may render coated papers more susceptible to certain types of damage (surface marring, embedded grime, and stains) and more reactive to certain conservation treatments. Several research projects have been undertaken to characterize paper coating compositions (by SEM/EDS and FTIR) and appearance properties (by SEM imaging of surface structure and quantitative measurements of color and gloss) in order to evaluate changes that might occur following application of solvents used in conservation treatments.
    [Show full text]
  • Flow Sheet Pulp and Paper Green Liquor / White Liquor Circuit
    WesTech’s Continuous Rotary Drum Filters provide a wide range of liquid-solids separation for many types of industrial processing flow sheets. They offer the operating flexibility to handle dewatering, washing, and filtration applications. Working with the customer, WesTech provides laboratory test data to assess process optimization, design, and sizing of the equipment supplied. WesTech Drum Filters are available up to 13.5 feet in diameter and 36 feet in length and are built for ease of operation as well as to meet demanding customer specifications. Pulp and Paper Dregs The most common process for making paper is called The dregs from the green liquor clarifier are sent to the Kraft or Kraft Mill process. In this process, wood a rotary vacuum filter called the “dregs filter.” Here chips are “cooked” at 150 - 165o C, under pressure the dregs are washed to remove residual chemicals in a liquid solution containing caustic (NaOH) and and are dewatered prior to disposal. The liquids are sodium sulphide (Na2S) to pulp the wood. recycled to the green liquor stabilization tank. White Liquor Slaker The solution of caustic and sodium sulfide is The clarified green liquor is fed to a “slaker” where referred to as “white liquor”. These chemicals, along NaOH is formed. The grit and unreacted lime settle with heat and pressure, release the lignin from the to the bottom where they are removed by means of fibers in the wood. The resulting “pulp” is washed, a screw conveyor. screened, and sent on to bleaching and becomes the feed stock for the paper-making process.
    [Show full text]