The advantage to mechanical pulping is that it produces much higher. Mechanical pulps can be produced by grinding logs or refining chips. Overview over the mains steps in mechanical pulping. Mechanical pulping processes use water for screening, cleaning, and showers on thickeners and grinding stones. The chemical process is energy selfsufficient as nearly all byproducts can be used to fire the pulp mill power plant. Pulping is done mechanically, thermomechanically, chemically, or with combinations of these treatments. Mechanical pulping at a crossroads it seems we are at a crossroads a turning point in the development of mechanical pulping. Much effort has been spent over the years to reduce this. Mechanical pulp ing processes include thermomechanical pulping tmp, chemimechanical cmp, chemithermome chancial pulping ctmp, and groundwood pulping. Thermomechanical pulping rapidly displaced traditional mechanical pulping, grinding, because similar paper properties could be achieved using fewer amounts of expensive reinforced kraft pulp. While high in energy consumption, tmp produces strong fibers, and clean steam can be recovered.
Low consistency refining combined with screen fractionation. Asplunds contribution to the pulp and paper industry worldwide. Process intensification is a term used in the chemical process industry for major improvements in the process design leading to radical changes in process complexity, equipment size and efficiency. The paper making process, the fifth technical brochure from sappi idea exchange idea exchange sappi is committed to helping printers and graphic designers use paper in the best possible way. Pulp is made by heating the chips with steam and mechanically separating the fibers in a pressurized refiner. In the mechanical pulping processes, fibers are separated from one another by mechanical energy applied to the wood matrix causing the bonds between fibers to break gradually and fiber bundles, single fibers and fiber fragments to be released. Mechanical pulps are ideally suited to lightweight printing grades because of their potential to make opaque, lowweight grades at low cost. The kraft process alone accounts for over 80 percent of the chemical pulp produced in the united states. Thermomechanical pulping tmp, chemithermomechanical pulping. Detailed knowledge of process mechanisms is crucial in. Olson pulp and paper centre, department of mechanical engineering, university of british columbia mechanical pulping comparison of mechanical and chemical pulps debarking stone groundwood refiner mechanical pulp thermo mechanical pulping tmp chemi thermo mechanical pulping ctmp. The pulping process is an important link in the papermaking industry. Pulp can be classified mainly into two types by the pulping methods. This site is like a library, use search box in the widget to get ebook that you want.
Today, thermomechanical pulping process is the most dominate mechanical pulping process. The following figure is the process flow chart of apmp. Mechanical pulping is one of the most electricityintensive processes in the pulp and paper industry, consuming 23. Me chanical pulping accounts for about 25% of the wood pulp production in the world today.
Commercial processes are generally classified as mechanical, chemical, or semi. Contrast of mechanical pulping and chemimechanical pulping. There are two main processes used for the manufacturing of mechanical pulping. Mechanical pulping processes handbook of pulp wiley online. Thermo mechanical pulping as a pretreatment for agricultural biomass for biochemical conversion ronalds gonzalez, hasan jameel, houmin chang, trevor treasure, adrian pirraglia, and daniel saloni the use of thermo mechanical pulping tmp, an existing and well known technology in the pulp and paper industry, is proposed as a. Mechanical pulp ing, with its high yield, is viewed as a way to extend these resources. Fibres mechanically removed from wood matrix chemical pulping. Pulp and paper pulp is the fibrous mass that results when a pulping process ruptures the bonds in the wood structure that hold the woody cells together. Pdf the nature of the mechanical pulping process researchgate. The chemical pulping process produces lower fibre yield than mechanical pulping. Hardwoods are normally used as raw material and the produced pulp is mainly used for production of corrugating medium fluting. Mechanical pulping consumes a great deal of electrical energy. Mechanical pulping is the process in which wood is separated or defibrated mechanically into pulp for the paper industry. A secondary objective was to determine the suitability of bugweed solanum mauritianum as a short fibre pulp using the above mentioned mechanical pulping.
To learn why it is important, we have to start from the pulp. Swelling of the wood is increased and the response to the mechanical pulping process is altered dramatically. It is the mixture of fibers and fiber fragments that gives mechanical pulp its favorable printing. First commercially viable kraft mill, sweden, 1885. This substantially reduces the electrical energy needed for mechanical pulping and leads to improvements in the paper strength properties. Mechanical pulping, 2nd edition mechanical pulping second. It is the paper pulp made from the fiber raw materials by mechanical grinding method, occupying an important position in the papermaking industry.
About 23% of the pulp used in the world is mechanical pulp. Excellent mechanical pulping solutions superior pulp quality at reduced energy consumption andritz knows how to meet the challenge of enhancing fiber quality with economical use of resources and offers complete mechanical pulping systems comprising highly efficient equipment in every process step. To be able to list several major pulping variables. The primary goals of pulping are to free fibers in wood from the lignin that binds these fibers together, and then to suspend the fibers in water into a slurry suitable for paper making. This occurs in rmp by the steam generation in the process.
The purpose of a mechanical pulping process is to separate the fibres from the wood matrix, hopefully in a form suitable for a specific papermaking process. Flowsheets for various mechanical pulping and screening processes. The first 3 display the greatest potential for causing air pollution. Evaluating chemical, mechanical, and biopulping processes. Reduction of mechanical pulping process complexity. Mechanical pulp, and especially thermomechanical pulp tmp is a major component of such paper. Inspired by process intensification methodology, we suggest five principles for development of the mechanical pulping process. A major early approach was the use of higher temperatures to soften the lignin. However, mechanical pulping is energyintensive and with rising energy costs, the challenge is to be able to apply the minimum energy to produce long, welldeveloped fibres from a variety of wood species. The concept ofusing fungal treatments in pulping processes, including refmer mechanical pulping. Mechanical pulping manual download ebook pdf, epub, tuebl, mobi. Wood structure parameters affecting the breakdown process. As the oldest form of pulping, mechanical pulping uses mechanical energy to weaken and separate fibers from wood via a grinding action.
The above method of producing groundwood pulp is the oldest pulping process. Process intensification is a process development methodology aimed at a considerable reduction in the energy consumption and process complexity. Steps in the pulp and papermaking process raw material preparation wood received at a pulp mill may be in several different forms, depending on the pulping process. Mechanical, semichemical, and sulfite pulp mills differ in detail, particularly in wood preparation, fiber separation, and bleaching, but many of the downstream refining, bleaching, and papermaking processes are similar. The nature of the mechanical pulping process semantic scholar. Chemi mechanical pulp aka cmp, including apmp, prc apmp. Historically, industrial pulp and paper production was a semiautomatic process which required a great deal of manual. In this process, pulp is produced by digesting wood chips at high temperature and pressure in a sodium hydroxide solution called white liquor to dissolve the wood lignin and other organic wood substances and to liberate the wood fibers that form the pulp and finally paper. The pulp and paper making processes princeton university. The competing chemical pulping process, the sulfate, or kraft, process, was developed by carl f. The kraft process is the dominating pulping process, which accounts for almost 60% of all mechanical and chemical pulp produced worldwide. Only a portion of the electricity used in grinders or refiners is converted into the mechanical work to liberate the fibers.
Nssc neutral sulfite semi chemical pulping is a type of semichemical pulping process to produce unbleached pulp at yields of around 80%. Mechanical pulp yields over 90% of the wood as fiber is produced by forcing debarked logs, about two meters long, and hot water between enormous rotating steel discs with teeth that literally tear the wood apart. The choice of pulping process is determined by the desired product, by the wood species available, and by economic considerations. By 1900, sulfite pulping had become the dominant means of producing wood pulp, surpassing mechanical pulping methods. To gain an overview picture of the primary operations and reactions occuring in the digesters between wood and the pulping chemicals. In addition to the primary steps in pulp and paper. In the second stage after refining, the pulp is screened, cleaned, and most of the process water is removed in preparation for paper making. The choice of pulping process is determined by the. Mechanical wood pulp is also known as ground wood pulp. The white water systems of the paper machine can be coupled countercurrently to the white water system of the mechanical pulping process. The category and application of paper pulping process mechanical wood pulp. In this process, pulp is produced by digesting wood chips at high temperature and pressure in a sodium hydroxide solution called white liquor to dissolve the wood lignin and other organic wood substances and. Thermomechanical pulping overview of the process thermomechanical pulping, tmp, is precisely named.
Exposure to the potential hazards listed in table 72. In the stone ground wood process sgw or in the pressurised ground wood process pgw logs are pressed against a rotating grinder stone with simultaneous addition of water. Click download or read online button to get mechanical pulping manual book now. Mechanical pulping volume 2 of the pulp and paper manufacture series page 4 of 5 raw material testing raw materials reboiler red maple red pine refined rejects, quality refiner mechanical pulping flowsheet operating conditions, survey refiner mechanical pulps comparison with gw effect of pressing sawdust softwoods refiner operation start up. In most usages, however, groundwood pulp is combined with pulps produced chemically, to counteract the disadvantages of paper made with mechanical pulps. However, mechanical pulping is energyintensive and with rising energy costs, the challenge is to be able to apply the minimum energy to produce long, welldeveloped fibres from a variety of wood. Mechanical pulping an overview sciencedirect topics. Christer sandberg, a,b, janerik berg, b and per engstrand b.
Pulp and paper manufacturing process in the paper industry. This report presents results from cruw mechanical pulping subproject 1. Pdf mechanical pulps are ideally suited to lightweight printing grades because of their potential to make opaque, lowweight grades at low. To gain an overview of some major kraft pulping trends. Paper pulp can be classified according to the type of raw material, paper pulping process and pulp yield. Regarded as the nobel prize in the field of mechanical pulping, the arne asplund mechanical pulping award was established in 1985 to commemorate dr. Mechanical pulping is the process in which wood is separated or defibrated mechanically into pulp for the paper industry the mechanical pulping processes use wood in the form of logs or chips that are mechanically processes, by grinding stones from logs or in refiners from chips, to separate the fibers.
In addition to fibre removal, fibres are broken and fines fibres pulp mass is in form of fines. The 4 processes principally used in chemical pulping are kraft, sulfite, neutral sulfite semichemical nssc, and soda. So we share our knowledge with customers, providing them with samples, specifications, ideas, technical information and a complete range of brochures. These chips are ground by passing them through rapidly rotating in both processes. Refiner pulp and thermo mechanical pulp are produced by chips. This is of course a demanding task, and for an outsider it might sound like magic that solid wood at all can be converted into useful fibres just by treating it mechanically. This understanding could unlock the potential value of each wood species, reduce process variability, and show how to make a mechanical pulp.