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48-512: The most prominent sight when arriving Lielahti is maybe the M-real pulp mill , which can sometimes also be sensed nasally. There is also a railway station in Lielahti, but its use in passenger traffic was discontinued in 1984 due to its lack of passengers. It remains though as a freight station used to transport pulp even today, and its most important function is as a railway junction, since

96-403: A mechanical mill. The conditions of the chemical treatment are much less vigorous (lower temperature, shorter time, less extreme pH) than in a chemical pulping process, since the goal is to make the fibers easier to refine, not to remove lignin as in a fully chemical process. Pulps made using these hybrid processes are known as Chemi-thermomechanical pulps (CTMP). Sometimes a CTMP mill is located on

144-479: A mechanical treatment to separate the fibers. These hybrid methods include thermomechanical pulping (TMP) and Chemi-thermomechanical pulping (CTMP). The chemical and thermal treatments reduce the amount of energy subsequently required by the mechanical treatment, and also reduce the amount of strength loss suffered by the fibers. The earliest known methods for preparing pulp for paper making were water-powered, in 8th-century Samarkand , Abbasid Caliphate . Much of

192-428: A staple food resource. The inner bark is eaten fresh, dried or roasted. Bark can be used as a construction material, and was used widely in pre-industrial societies. Some barks, particularly Birch bark, can be removed in long sheets and other mechanically cohesive structures, allowing the bark to be used in the construction of canoes, as the drainage layer in roofs, for shoes, backpacks, and other useful items. Bark

240-434: A surface for paintings and map making. A number of plants are also grown for their attractive or interesting bark colorations and surface textures or their bark is used as landscape mulch . The process of removing bark is decortication and a log or trunk from which bark has been removed is said to be decorticated . Bark is present only on woody plants - herbaceous plants and stems of young plants lack bark. From

288-512: A thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods ( kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements. Wood and other plant materials used to make pulp contain three main components (apart from water): cellulose fibres (desired for papermaking ), lignin (a three-dimensional polymer that binds

336-470: A thick porridge-like consistency and is "blown" or squeezed from the outlet of the digester through an airlock. The sudden change in pressure results in a rapid expansion of the fibers, separating the fibers even more. The resulting fiber suspension in water solution is called "brown stock". Brown stock washers, using countercurrent flow, remove the spent cooking chemicals and degraded lignin and hemicellulose. The extracted liquid, known as black liquor in

384-441: Is a long tradition in northern Europe of using bark from coppiced young branches of the small-leaved lime ( Tilia cordata ) to produce cordage and rope , used for example in the rigging of Viking Age longships . Among the commercial products made from bark are cork , cinnamon , quinine (from the bark of Cinchona ) and aspirin (from the bark of willow trees). The bark of some trees, notably oak ( Quercus robur )

432-447: Is a source of tannic acid , which is used in tanning . Bark chips generated as a by-product of lumber production are often used in bark mulch . Bark is important to the horticultural industry since in shredded form it is used for plants that do not thrive in ordinary soil, such as epiphytes . Wood bark contains lignin which when pyrolyzed yields a liquid bio-oil product rich in natural phenol derivatives. These are used as

480-399: Is edible. In hunter-gatherer societies and in times of famine, it is harvested and used as a food source. In Scandinavia, bark bread is made from rye to which the toasted and ground innermost layer of bark of scots pine or birch is added. The Sami people of far northern Europe use large sheets of Pinus sylvestris bark that are removed in the spring, prepared and stored for use as

528-416: Is even more difficult to remove. In chemical pulp mills, the bark introduces unwanted contaminants such as calcium , silica , and aluminum that cause scaling and give an extra loading for the chemical recovery system. Birchbark contains betulin , a terpenoid that easily creates deposits in a pulp mill. The earliest mills used sandstone grinding rollers to break up small wood logs called "bolts", but

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576-529: Is generally thickest and most distinctive at the trunk or bole (the area from the ground to where the main branching starts) of the tree. Bark tissues make up by weight between 10 and 20% of woody vascular plants and consists of various biopolymers , tannins , lignin , suberin and polysaccharides . Up to 40% of the bark tissue is made of lignin, which forms an important part of a plant, providing structural support by crosslinking between different polysaccharides, such as cellulose. Condensed tannin , which

624-406: Is in fairly high concentration in bark tissue, is thought to inhibit decomposition . It could be due to this factor that the degradation of lignin is far less pronounced in bark tissue than it is in wood. It has been proposed that, in the cork layer (the phellogen), suberin acts as a barrier to microbial degradation and so protects the internal structure of the plant. Analysis of the lignin in

672-445: Is mixed with an aqueous solution of the pulping chemicals, then heated with steam. In the kraft process the pulping chemicals are sodium hydroxide and sodium sulfide and the solution is known as white liquor. In the sulfite process the pulping chemical is a mixture of metal (sodium, magnesium, potassium, or calcium) and ammonium sulfite or sulfite. After several hours in the digester, the chips or cut plant material breaks down into

720-593: Is quite variable across species and type of damage. Some are able to produce a callus growth which heals over the wound rapidly, but leaves a clear scar, whilst others such as oaks do not produce an extensive callus repair. Sap is sometimes produced to seal the damaged area against disease and insect intrusion. A number of living organisms live in or on bark, including insects, fungi and other plants like mosses, algae and other vascular plants. Many of these organisms are pathogens or parasites but some also have symbiotic relationships. The inner bark ( phloem ) of some trees

768-402: Is removed by pressing the sheet of fibers, and the sheet is then dried. At this point the sheets of pulp are several millimeters thick and have a coarse surface: it is not yet paper. The dried pulp is cut, stacked, bailed and shipped to another facility for whatever further process is needed. Bleached kraft pulp and bleached sulfite pulp are used to make high quality, white printing paper. One of

816-414: The bleach plant . Bark (botany) Bark is the outermost layer of stems and roots of woody plants . Plants with bark include trees , woody vines , and shrubs . Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes

864-429: The cellulose fibres together) and hemicelluloses , (shorter branched carbohydrate polymers). The aim of pulping is to break down the bulk structure of the fiber source, be it chips, stems or other plant parts, into the constituent fibers. Chemical pulping achieves this by degrading the lignin and hemicellulose into small, water-soluble molecules that can be washed away from the cellulose fibers without depolymerizing

912-433: The cork cambium . It serves as protection against damage from parasites , herbivorous animals and diseases, as well as dehydration and fire. Often a secondary covering called the periderm forms on small woody stems and many non-woody plants, which is composed of cork (phellem), the cork cambium (phellogen), and the phelloderm. The periderm forms from the phellogen which serves as a lateral meristem. The periderm replaces

960-428: The pulp and paper industry for two primary reasons, to avoid iron contamination of the product and their corrosion resistance to the various chemicals used in the papermaking process. A wide range of stainless steels are used throughout the pulp making process. For example, duplex stainless steels are being used in digesters to convert wood chips into wood pulp and 6% Mo super austenitic stainless steels are used in

1008-446: The bark wall during decay by the white-rot fungi Lentinula edodes ( Shiitake mushroom ) using C NMR revealed that the lignin polymers contained more Guaiacyl lignin units than Syringyl units compared to the interior of the plant. Guaiacyl units are less susceptible to degradation as, compared to syringyl, they contain fewer aryl-aryl bonds, can form a condensed lignin structure, and have a lower redox potential . This could mean that

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1056-501: The cellulose fibers (chemically depolymerizing the cellulose weakens the fibers). The various mechanical pulping methods, such as groundwood (GW) and refiner mechanical (RMP) pulping, physically tear the cellulose fibers one from another. Much of the lignin remains adhering to the fibers. Strength is impaired because the fibers may be cut. Related hybrid pulping methods use a combination of chemical and thermal treatment to begin an abbreviated chemical pulping process, followed immediately by

1104-414: The chips are just ground up with the plates, the pulp is called "refiner mechanical" pulp (RMP), if the chips are steamed while being refined the pulp is called "thermomechanical" pulp (TMP). Steam treatment significantly reduces the total energy needed to make the pulp and decreases the damage (cutting) to fibers. Mechanical pulp mills use large amounts of energy, mostly electricity to power motors which turn

1152-460: The concentration and type of lignin units could provide additional resistance to fungal decay for plants protected by bark. Bark can sustain damage from environmental factors, such as frost crack and sun scald , as well as biological factors, such as woodpecker and boring beetle attacks. Male deer and other male members of the Cervidae (deer family) can cause extensive bark damage during

1200-435: The cork cambium and the vascular cambium , are the only parts of a woody stem where cell division occurs; undifferentiated cells in the vascular cambium divide rapidly to produce secondary xylem to the inside and secondary phloem to the outside. Phloem is a nutrient -conducting tissue composed of sieve tubes or sieve cells mixed with parenchyma and fibers. The cortex is the primary tissue of stems and roots. In stems

1248-400: The cortex is between the epidermis layer and the phloem, in roots the inner layer is not phloem but the pericycle . As the stem ages and grows, changes occur that transform the surface of the stem into the bark. The epidermis is a layer of cells that cover the plant body, including the stems, leaves, flowers and fruits, that protects the plant from the outside world. In old stems

1296-439: The cracks of the cork layers. The rhytidome is the most familiar part of bark, being the outer layer that covers the trunks of trees. It is composed mostly of dead cells and is produced by the formation of multiple layers of suberized periderm, cortical and phloem tissue. The rhytidome is especially well developed in older stems and roots of trees. In shrubs, older bark is quickly exfoliated and thick rhytidome accumulates. It

1344-419: The epidermal layer, cortex, and primary phloem become separated from the inner tissues by thicker formations of cork. Due to the thickening cork layer these cells die because they do not receive water and nutrients. This dead layer is the rough corky bark that forms around tree trunks and other stems. Cork, sometimes confused with bark in colloquial speech, is the outermost layer of a woody stem, derived from

1392-409: The epidermis, and acts as a protective covering like the epidermis. Mature phellem cells have suberin in their walls to protect the stem from desiccation and pathogen attack. Older phellem cells are dead, as is the case with woody stems. The skin on the potato tuber (which is an underground stem) constitutes the cork of the periderm. In woody plants, the epidermis of newly grown stems is replaced by

1440-430: The epidermis, cortex and older secondary phloem die. Within the periderm are lenticels , which form during the production of the first periderm layer. Since there are living cells within the cambium layers that need to exchange gases during metabolism, these lenticels, because they have numerous intercellular spaces, allow gaseous exchange with the outside atmosphere. As the bark develops, new lenticels are formed within

1488-411: The grinders. A rough estimate of the electrical energy needed is 10,000 mega joules (MJ) per tonne of pulp (2,750  kWh per tonne ) Chemical pulping processes such as the kraft (or sulfate) process and the sulfite process remove much of the hemicelluloses and lignin. The kraft process does less damage to the cellulose fibers than the sulfite process , thereby producing stronger fibers, but

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1536-495: The information about the technology in following subsections is from the book by C.J. Biermann. The chemistry of the various pulping processes can be found in Sjöström's book. The most common fiber source for pulp mills is pulpwood . Other common sources are bagasse and fibre crops. The first step in all mills using wood (trees) as the fiber source is to remove the bark . Bark contains relatively few usable fibers and darkens

1584-608: The innermost layer of the periderm. The outer bark on older stems includes the dead tissue on the surface of the stems, along with parts of the outermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the living periderm is also called the rhytidome . Products derived from bark include bark shingle siding and wall coverings, spices, and other flavorings, tanbark for tannin , resin , latex , medicines, poisons, various hallucinogenic chemicals, and cork . Bark has been used to make cloth, canoes, and ropes and used as

1632-445: The kraft process, and red or brown liquor in the sulfite processes, is concentrated, burned and the sodium and sulfur compounds recycled in the recovery process. Lignosulphonates is a useful byproduct recovered from the spent liquor in the sulfite process. The clean pulp (stock) can be bleached in the bleach plant or left unbleached, depending on the end-use. The stock is sprayed onto the pulp machine wire, water drains off, more water

1680-579: The most visible uses for unbleached kraft pulp is to make brown paper shopping bags and wrapping paper where strength is particularly important. A special grade of bleached sulfite pulp, known as dissolving pulp, is used to make cellulose derivatives such as methylcellulose which are used in a wide range of everyday products from laxatives to baked goods to wallpaper paste . Some mills pretreat wood chips or other plant material like straw with sodium carbonate , sodium hydroxide , sodium sulfite , and other chemical prior to refining with equipment similar to

1728-414: The outside to the inside of a mature woody stem, the layers include the following: In young stems, which lack what is commonly called bark, the tissues are, from the outside to the inside: Cork cell walls contain suberin , a waxy substance which protects the stem against water loss, the invasion of insects into the stem, and prevents infections by bacteria and fungal spores. The cambium tissues, i.e.,

1776-411: The periderm later in the year. As the stems grow a layer of cells form under the epidermis, called the cork cambium, these cells produce cork cells that turn into cork. A limited number of cell layers may form interior to the cork cambium, called the phelloderm. As the stem grows, the cork cambium produces new layers of cork which are impermeable to gases and water and the cells outside the periderm, namely

1824-588: The plant. Bark serves as a physical barrier to disease pressure, especially from fungi, so its removal makes the plant more susceptible to disease. Damage or destruction of the phloem impedes the transport of photosynthetic products throughout the plant; in extreme cases, when a band of phloem all the way around the stem is removed, the plant will usually quickly die. Bark damage in horticultural applications, as in gardening and public landscaping, results in often unwanted aesthetic damage. The degree to which woody plants are able to repair gross physical damage to their bark

1872-407: The probability of a disturbance or breakdown. Each stage also may have different decision variables, such as steam / water / chemical input, etc. Finally, scheduling needs to consider fuel optimization and CO 2 emissions, because part of the energy requirements may be met from fossil-fuel boilers. The overall aim is to maximize production at minimum cost. Stainless steels is used extensively in

1920-422: The pulp. The removed bark is burned, along with other unusable plant material, to generate steam to run the mill. Almost all wood is then chipped before being processed further in order to free the fibers. Removal of the bark is done in a barker (or debarker ). The bark adhesion is about 3–5 kg/cm in the growing season (summer) and 2-3 times higher in the dormant season (winter). The bark of frozen logs

1968-405: The pulping liquor to penetrate the pieces completely. In the case of wood, the logs are chipped and the chips screened to ensure that the feed to the digester is of a uniform size. Oversized chips are either used as fuel or run through the chipper again, while sawdust may be burned or collected for sale. The screened chips or cut plant material ( bamboo , kenaf , etc.) goes to the digester where it

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2016-472: The railway tracks from Pori (Björneborg) and Seinäjoki merge there, continuing as a double-track railway to the main station of Tampere. The National Board of Antiquities has classified the Lielahti station area as a nationally significant protected site. In the future it is quite likely that local public transport in Tampere region will again be provided by commuter trains , in a way or another. Then

2064-479: The rutting season by rubbing their antlers against the tree to remove their velvet . The bark is often damaged by being bound to stakes or wrapped with wires. In the past, this damage was called bark-galling and was treated by applying clay laid on the galled place and binding it up with hay . In modern usage, "galling" most typically refers to a type of abnormal growth on a plant caused by insects or pathogens. Bark damage can have several detrimental effects on

2112-472: The same site as a kraft mill so that the effluent from the CTMP mill can be treated in the kraft recovery process to regenerate the inorganic pulping chemicals. The pulping process involves many production stages, usually coupled with intermediate storage tanks. As each stage has a different reliability and bottlenecks may vary from day to day, scheduling a pulp mill needs to take into account these bottlenecks and

2160-417: The sulfite process makes pulp that is easier to bleach. The chemical pulping processes use a combination of high temperature and alkaline (kraft) or acidic (sulfite) chemicals to break the chemical bonds of the lignin. However, atmospheric pollution and contaminants in wastewater effluent in the kraft pulping process has been widely documented The material fed into the digester must be small enough to allow

2208-434: The trains bound from and to Nokia , and perhaps from and to Ylöjärvi will stop at the Lielahti station. 61°31′N 23°40′E  /  61.517°N 23.667°E  / 61.517; 23.667 This Western Finland location article is a stub . You can help Misplaced Pages by expanding it . Pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into

2256-446: The use of natural stone ended in the 1940s with the introduction of manufactured stones with embedded silicon carbide or aluminum oxide . The pulp made by this process is known as "stone groundwood" pulp (SGW). If the wood is ground in a pressurized, sealed grinder the pulp is classified as "pressure groundwood" (PGW) pulp. Most modern mills use chips rather than logs and ridged metal discs called refiner plates instead of grindstones. If

2304-657: Was also used as a construction material in settler colonial societies, particularly Australia, both as exterior wall cladding and as a roofing material. In the cork oak ( Quercus suber ) the bark is thick enough to be harvested as a cork product without killing the tree; in this species the bark may get very thick (e.g. more than 20 cm has been reported ). Some stem bark s have significantly different phytochemical content from other parts. Some of these phytochemicals have pesticidal , culinary, or medicinally and culturally important ethnopharmacological properties. Bark contains strong fibres known as bast , and there

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