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Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating
cellulose fiber Cellulose fibers () are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants, or from other plant-based material. In addition to cellulose, the fibers may also contain hemicellulose and l ...
s from
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
,
fiber crop Fiber crops are field crops grown for their fibers, which are traditionally used to make paper, cloth, or rope. Fiber crops are characterized by having a large concentration of cellulose, which is what gives them their strength. The fibers may b ...
s,
waste paper The recycling of paper is the process by which waste paper is turned into new paper products. It has a number of important benefits: It saves waste paper from occupying homes of people and producing methane as it breaks down. Because paper fib ...
, or
rag Rag, rags, RAG or The Rag may refer to: Common uses * Rag, a piece of old cloth * Rags, tattered clothes * Rag (newspaper), a publication engaging in tabloid journalism * Rag paper, or cotton paper Arts and entertainment Film * ''Rags'' (1915 ...
s. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
and the industrial production of other
paper products Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
.


History

Before the widely acknowledged invention of
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
by
Cai Lun Cai Lun (; courtesy name: Jingzhong (); – 121 CE), formerly romanized as Ts'ai Lun, was a Chinese eunuch court official of the Eastern Han dynasty. He is traditionally regarded as the inventor of paper and the modern papermaking process ...
in China around 105 AD, paper-like writing materials such as
papyrus Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, '' Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'') can also refer to a ...
and
amate Amate ( es, amate from nah, āmatl ) is a type of bark paper that has been manufactured in Mexico since the precontact times. It was used primarily to create codices. Amate paper was extensively produced and used for both communication, record ...
were produced by ancient civilizations using plant materials which were largely unprocessed. Strips of bark or bast material were woven together, beaten into rough sheets, dried, and polished by hand. Pulp used in modern and traditional
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
is distinguished by the process which produces a finer, more regular slurry of cellulose fibers which are pulled out of solution by a screen and dried to form sheets or rolls. The earliest paper produced in China consisted of bast fibers from the paper mulberry (kozo) plant along with
hemp Hemp, or industrial hemp, is a botanical class of ''Cannabis sativa'' cultivars grown specifically for industrial or medicinal use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants o ...
rag and net scraps. By the 6th century, the mulberry tree was domesticated by farmers in China specifically for the purpose of producing pulp to be used in the papermaking process. In addition to mulberry, pulp was also made from
bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...
,
hibiscus ''Hibiscus'' is a genus of flowering plants in the mallow family, Malvaceae. The genus is quite large, comprising several hundred species that are native to warm temperate, subtropical and tropical regions throughout the world. Member species ...
bark, blue sandalwood,
straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
, and
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor perce ...
. Papermaking using pulp made from hemp and
linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong, absorbent, and dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. It also ...
fibers from tattered clothing, fishing nets and fabric bags spread to Europe in the 13th century, with an ever-increasing use of rags being central to the manufacture and affordability of
rag paper Rag, rags, RAG or The Rag may refer to: Common uses * Rag, a piece of old cloth * Rags, tattered clothes * Rag (newspaper), a publication engaging in tabloid journalism * Rag paper, or cotton paper Arts and entertainment Film * ''Rags'' (1915 ...
, a factor in the development of
printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ea ...
. By the 1800s, production demands on the newly industrialized papermaking and printing industries led to a shift in raw materials, most notably the use of
pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gener ...
and other tree products which today make up more than 95% of global pulp production. The use of wood pulp and the invention of automatic
paper machine A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machin ...
s in the late 18th- and early 19th-century contributed to paper's status as an inexpensive commodity in modern times. While some of the earliest examples of paper made from wood pulp include works published by
Jacob Christian Schäffer Jacob Christian Schäffer, alternatively Jakob, (31 May 1718 – 5 January 1790) was a German dean, professor, botanist, mycologist, entomologist, ornithologist and inventor. Biography From 1736 to 1738 he studied Theology at the University of ...
in 1765 and
Matthias Koops Matthias Koops (active 1789–1805) was a British paper-maker who invented the first practical processes for manufacturing paper from wood pulp, straw, or recycled waste paper, without the necessity of including expensive linen or cotton rags. K ...
in 1800, large-scale wood paper production began in the 1840s with unique, simultaneous developments in mechanical pulping made by
Friedrich Gottlob Keller Friedrich Gottlob Keller (born 27 June 1816 in Hainichen, Saxony; died 8 September 1895 in Krippen, Saxony) was a German machinist and invention, inventor, who (at the same time as Charles Fenerty) invented the pulp (paper), wood pulp process for u ...
in Germany and by
Charles Fenerty Charles Fenerty (January 1821 – 10 June 1892), was a Canadian inventor who invented the wood pulp process for papermaking, which was first adapted into the production of newsprint. Fenerty was also a poet (writing over 32 known poems). Early ...
in
Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...
.Burger, Peter
'Charles Fenerty and his Paper Invention''. Toronto: Peter Burger, 2007. pp.25–30
Chemical processes quickly followed, first with
J. Roth ''J. The Jewish News of Northern California'', formerly known as ''Jweekly'', is a weekly print newspaper in Northern California, with its online edition updated daily. It is owned and operated by San Francisco Jewish Community Publications In ...
's use of
sulfurous acid Sulfurous acid (also sulfuric(IV) acid, sulphurous acid (UK), sulphuric(IV) acid (UK)) is the chemical compound with the formula . There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase. ...
to treat wood, then by Benjamin Tilghman's
U.S. patent Under United States law, a patent is a right granted to the inventor of a (1) process, machine, article of manufacture, or composition of matter, (2) that is new, useful, and non-obvious. A patent is the right to exclude others, for a limited ...
on the use of
calcium bisulfite Calcium bisulfite (calcium bisulphite) is an inorganic compound which is the salt (chemistry), salt of a calcium cation and a bisulfite anion. It may be prepared by treating lime with an excess of sulfur dioxide and water. As a food additive it is ...
, Ca(HSO3)2, to pulp wood in 1867. Almost a decade later, the first commercial sulfite pulp mill was built, in Sweden. It used
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
as the
counter ion 160px, Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion.">cation-exchange_resin.html" ;"title="Polystyrene sulfonate, a cation-exchange resin">Polystyrene sulfonate, a cation-exchange resin, is typical ...
and was based on work by
Carl Daniel Ekman Carl Daniel Ekman (March 17, 1845 – November 3, 1904) was a Swedish chemical engineer who invented the form of the sulfite process of wood pulp manufacturing which was first established on a firm commercial basis, helping to replace rags as the ...
. By 1900, sulfite pulping had become the dominant means of producing wood pulp, surpassing mechanical pulping methods. The competing chemical pulping process, the sulfate, or kraft, process, was developed by
Carl F. Dahl Carl may refer to: *Carl, Georgia, city in USA *Carl, West Virginia, an unincorporated community *Carl (name), includes info about the name, variations of the name, and a list of people with the name *Carl², a TV series * "Carl", List of Aqua Teen ...
in 1879; the first kraft mill started, in Sweden, in 1890. The invention of the
recovery boiler Recovery boiler is the part of kraft process of pulping where chemicals for white liquor are recovered and reformed from black liquor, which contains lignin from previously processed wood. The black liquor is burned, generating heat, which is usual ...
, by
G.H. Tomlinson GH, Gh, gh, or .gh may refer to: * gh (digraph), a digraph found in many languages * Gästrike-Hälsinge nation, a student association at Uppsala University, Sweden * ''General Hospital'', an American daytime medical drama * Ghana (ISO 3166-1 alph ...
in the early 1930s, allowed kraft mills to recycle almost all of their pulping chemicals. This, along with the ability of the kraft process to accept a wider variety of types of wood and to produce stronger fibres, made the kraft process the dominant pulping process, starting in the 1940s. Global production of wood pulp in 2006 was 175 million tons (160 million tonnes). In the previous year, 63 million tons (57 million tonnes) of market pulp (not made into paper in the same facility) was sold, with Canada being the largest source at 21 percent of the total, followed by the United States at 16 percent. The
wood fiber Wood fibres (also spelled wood fibers, see spelling differences) are usually cellulosic elements that are extracted from trees and used to make materials including paper. The end paper product (paper, paperboard, tissue, cardboard, etc.) dictate ...
sources required for pulping are "45% sawmill residue, 21% logs and chips, and 34% recycled paper" (Canada, 2014). Chemical pulp made up 93% of market pulp.


Wood pulp

The
timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...
resources used to make wood pulp are referred to as
pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gener ...
. While in theory any tree can be used for pulp-making,
coniferous trees Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extan ...
are preferred because the cellulose fibers in the pulp of these species are longer, and therefore make stronger paper. Some of the most commonly used
softwood file:Pinus sylvestris wood ray section 1 beentree.jpg, Scots Pine, a typical and well-known softwood Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees. The main diff ...
trees for paper making include
spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
,
pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
, fir,
larch Larches are deciduous conifers in the genus ''Larix'', of the family Pinaceae (subfamily Laricoideae). Growing from tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains furt ...
and hemlock, and
hardwood Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...
s such as
eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...
,
aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the ''Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (China ...
and
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...
. There is also increasing interest in genetically modified tree species (such as GM
eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...
and GM poplar) because of several major benefits these can provide, such as increased ease of breaking down lignin and increased growth rate. A
pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or ful ...
is a manufacturing facility that converts wood chips or other plant fibre source into a thick fiberboard which can be shipped to a
paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, ...
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 fibers (desired for papermaking),
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
(a three-dimensional polymer that binds the cellulose fibres together) and
hemicellulose A hemicellulose (also known as polyose) is one of a number of heteropolymer, heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all embryophyte, terrestrial plant cell walls.Scheller HV, Ulvskov H ...
s (shorter branched
carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s). The aim of pulping is to break down the bulk structure of the fibre source, be it chips, stems or other plant parts, into the constituent fibres. Chemical pulping achieves this by degrading the lignin and hemicellulose into small, water-soluble molecules which can be washed away from the cellulose fibres without depolymerizing the cellulose fibres (chemically depolymerizing the cellulose weakens the fibres). The various mechanical pulping methods, such as groundwood (GW) and refiner mechanical pulping (RMP), physically tear the cellulose fibres one from another. Much of the lignin remains adhering to the fibres. Strength is impaired because the fibres may be cut. There are a number of related hybrid pulping methods that use a combination of chemical and thermal treatment to begin an abbreviated chemical pulping process, followed immediately by a mechanical treatment to separate the fibres. These hybrid methods include thermomechanical pulping, also known as TMP, and chemithermomechanical pulping, also known as 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 fibres.


Harvesting trees

Most pulp mills use good
forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management for ...
practices in harvesting trees to ensure that they have a sustainable source of raw materials. One of the major complaints about harvesting wood for pulp mills is that it reduces the
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
of the harvested forest. Pulp tree plantations account for 16 percent of world pulp production,
old-growth forest An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...
s 9 percent, and second- and third- and more generation forests account for the rest.
Reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debate ...
is practiced in most areas, so trees are a
renewable resource A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion resource depletion, depleted by usage and consumption, either through natural reproduction or other recurring processes in a ...
. The FSC (
Forest Stewardship Council The Forest Stewardship Council A. C. (FSC) is an international non-profit, multistakeholder organization established in 1993 that promotes responsible management of the world's forests via timber certification. It is an example of a market-ba ...
), SFI (
Sustainable Forestry Initiative The Sustainable Forestry Initiative (SFI) is a sustainability organization operating in the U.S. and Canada that works across four pillars: standards, conservation, community, and education. SFI has two youth education initiatives: Project Learning ...
), PEFC (
Programme for the Endorsement of Forest Certification The Programme for the Endorsement of Forest Certification (PEFC) is an international, non-profit, non-governmental organization which promotes sustainable forest management through independent third party certification. It is considered the certi ...
), and other bodies certify paper made from trees harvested according to guidelines meant to ensure good forestry practices. The number of trees consumed depends on whether mechanical processes or chemical processes are used. It has been estimated that based on a mixture of
softwood file:Pinus sylvestris wood ray section 1 beentree.jpg, Scots Pine, a typical and well-known softwood Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees. The main diff ...
s and
hardwood Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...
s 12 metres (40 ft) tall and 15–20 centimetres (6–8 in) in diameter, it would take an average of 24 trees to produce 0.9 tonne (1 ton) of printing and writing paper, using the
kraft process The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chip ...
(chemical pulping). Mechanical pulping is about twice as efficient in using trees, since almost all of the wood is used to make fibre, therefore it takes about 12 trees to make 0.9 tonne (1 ton) of mechanical pulp or
newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has an ...
. There are roughly two short tons in a
cord of wood Cord or CORD may refer to: People * Alex Cord (1933–2021), American actor and writer * Chris Cord (born 1940), American racing driver * Errett Lobban Cord (1894–1974) American industrialist * Ronnie Cord (1943–1986), Brazilian singer * Cor ...
.


Preparation for pulping

Wood chipping is the act and industry of chipping wood for pulp, but also for other processed wood products and
mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area. A m ...
. Only the
heartwood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin tha ...
and sapwood are useful for making pulp. Bark contains relatively few useful fibers and is removed and used as fuel to provide steam for use in the pulp mill. Most pulping processes require that the wood be chipped and screened to provide uniform sized chips.


Pulping

There are a number of different processes which can be used to separate the wood fiber:


Mechanical pulp

Manufactured
grindstone A grindstone, also known as grinding stone, is a sharpening stone used for grinding or sharpening ferrous tools, used since ancient times. Tools are sharpened by the stone's abrasive qualities that remove material from the tool through friction ...
s with embedded
silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal sin ...
or aluminum oxide can be used to grind small wood logs called "bolts" to make stone pulp (SGW). If the wood is steamed prior to grinding it is known as pressure ground wood pulp (PGW). Most modern mills use chips rather than logs and ridged metal discs called refiner plates instead of grindstones. If the chips are just ground up with the plates, the pulp is called refiner mechanical pulp (RMP) and 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 fibres. Mechanical pulps are used for products that require less strength, such as
newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has an ...
and
paperboard Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 Inch#equivalences, points) than paper and has certain ...
s.


Thermomechanical pulp

Thermomechanical pulp is pulp produced by processing
wood chips Woodchips are small- to medium-sized pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. Woodchips may be used as a biomass solid fuel and are raw materia ...
using heat (thus " thermo-") and a mechanical refining movement (thus "-mechanical"). It is a two-stage process where the logs are first stripped of their bark and converted into small chips. These chips have a moisture content of around 25–30 percent. A mechanical force is applied to the wood chips in a crushing or grinding action which generates heat and water vapour and softens the
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
thus separating the individual fibres. The pulp is then screened and cleaned, any clumps of fibre are reprocessed. This process gives a high yield of fibre from the
timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, wi ...
(around 95 percent) and as the lignin has not been removed, the fibres are hard and rigid.


Chemi-thermomechanical pulp

Wood chips can be pre-treated with
sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
,
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...
,
sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 milli ...
and other chemicals prior to refining with equipment similar to 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).


Chemical pulp

Chemical pulp is produced by combining wood chips and chemicals in large vessels called digesters. There, heat and chemicals break down lignin, which binds
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
fibres together, without seriously degrading the
cellulose fibre Cellulose fibers () are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants, or from other plant-based material. In addition to cellulose, the fibers may also contain hemicellulose and li ...
s. Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product different characteristics. The
kraft process The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chip ...
is the dominant chemical pulping method, with the
sulfite process The sulfite process produces wood pulp that is almost pure cellulose fibers by treating wood chips with solutions of sulfite and bisulfite ions. These chemicals cleave the bonds between the cellulose and lignin components of the lignocellulose. A ...
second. Historically
soda pulping Soda pulping is a chemical process for making wood pulp with sodium hydroxide as the cooking chemical. In the ''Soda-AQ'' process, anthraquinone (AQ) may be used as a pulping additive to decrease the carbohydrate degradation. The soda process give ...
was the first successful chemical pulping method.


Recycled pulp

Recycled pulp is also called deinked pulp (DIP). DIP is
recycled paper The recycling of paper is the process by which waste paper is turned into new paper products. It has a number of important benefits: It saves waste paper from occupying homes of people and producing methane as it breaks down. Because paper fi ...
which has been processed by chemicals, thus removing
printing ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicke ...
s and other unwanted elements and freed the paper fibres. The process is called
deinking Deinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp. The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical ac ...
. DIP is used as raw material in
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
. Many
newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has an ...
,
toilet paper Toilet paper (sometimes called toilet tissue or bathroom tissue) is a tissue paper product primarily used to clean the anus and surrounding anal region of feces after defecation, and to clean the perineal area and external genitalia of u ...
and
facial tissue Facial tissue and paper handkerchief refers to a class of soft, absorbent, disposable papers that are suitable for use on the face. They are disposable alternatives for cloth handkerchiefs. The terms are commonly used to refer to the type of pap ...
grades commonly contain 100 percent deinked pulp and in many other grades, such as lightweight coated for offset and printing and writing papers for office and home use, DIP makes up a substantial proportion of the furnish.


Organosolv pulping

Organosolv pulping uses organic solvents at temperatures above 140 °C to break down lignin and hemicellulose into soluble fragments. The pulping liquor is easily recovered by distillation. The reason for using a solvent is to make the
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
more soluble in the cooking liquor. Most common used solvents are
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
,
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
,
formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...
and
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...
often in combination with
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
.


Alternative pulping methods

Research is under way to develop biopulping (biological pulping), similar to chemical pulping but using certain species of
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
that are able to break down the unwanted lignin, but not the cellulose fibres. In the biopulping process, the fungal enzyme
lignin peroxidase In enzymology, a lignin peroxidase () is an enzyme that catalyzes the chemical reaction :1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol + H2O2 \rightleftharpoons 3,4-dimethoxybenzaldehyde + 1-(3,4-dimethoxyphenyl)ethane-1,2-diol + H2O Thus, the ...
selectively digests lignin to leave remaining cellulose fibres. This could have major environmental benefits in reducing the pollution associated with chemical pulping. The pulp is bleached using
chlorine dioxide Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually ...
stage followed by neutralization and
calcium hypochlorite Calcium hypochlorite is an inorganic compound with formula Ca(OCl)2. It is the main active ingredient of commercial products called bleaching powder, chlorine powder, or chlorinated lime, used for water treatment and as a bleaching agent. Thi ...
. The
oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or "Electron acceptor, accepts"/"receives" an electron from a (called the , , or ). In ot ...
in either case oxidizes and destroys the dyes formed from the
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', ...
s of the wood and accentuated (reinforced) by
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
s present in it. Steam exploded fibre is a pulping and extraction technique that has been applied to wood and other fibrous organic material.


Bleaching

The pulp produced up to this point in the process can be bleached to produce a
white paper A white paper is a report or guide that informs readers concisely about a complex issue and presents the issuing body's philosophy on the matter. It is meant to help readers understand an issue, solve a problem, or make a decision. A white paper ...
product. The chemicals used to bleach pulp have been a source of environmental concern, and recently the pulp industry has been using alternatives to
chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
, such as
chlorine dioxide Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually ...
,
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
,
ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
and
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
.


Alternatives to wood pulp

Pulp made from non-wood plant sources or recycled textiles is manufactured today largely as a speciality product for fine-printing and art purposes. Modern machine- and hand-made art papers made with cotton, linen, hemp, abaca, kozo, and other fibers are often valued for their longer, stronger fibers and their lower
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
content.
Lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
, present in virtually all plant materials, contributes to the acidification and eventual breakdown of paper products, often characterized by the browning and embrittling of paper with a high lignin content such as
newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has an ...
. 100% cotton or a combination of cotton and linen pulp is widely used to produce documents intended for long-term use, such as certificates, currency, and passports. Today, some groups advocate using field crop fibre or agricultural residues instead of wood fibre as a more
sustainable Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livin ...
means of production. There is enough
straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
to meet much of North America's book, magazine, catalogue and copy paper needs. Agricultural-based paper does not come from
tree farm In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are u ...
s. Some agricultural residue pulps take less time to cook than wood pulps. That means agricultural-based paper uses less energy, less water and fewer chemicals. Pulp made from wheat and flax straw has half the ecological footprint of pulp made from forests.
Hemp paper Hemp paper is paper varieties consisting exclusively or to a large extent from pulp obtained from fibers of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood ...
is a possible replacement, but processing infrastructure, storage costs and the low usability percentage of the plant means it is not a ready substitute. However, wood is also a renewable resource, with about 90 percent of pulp coming from
plantation A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. The ...
s or reforested areas. Non-wood fibre sources account for about 5–10 percent of global pulp production, for a variety of reasons, including seasonal availability, problems with chemical recovery, brightness of the pulp etc. In China, as of 2009, a higher proportion of non-wood pulp processing increased use of water and energy.
Nonwovens Nonwoven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabri ...
are in some applications alternatives to paper made from wood pulp, like
filter paper Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases. The raw materials are different paper pulps. The pulp may be made from softwood, hardwo ...
or
tea bag A tea bag, or the compound teabag, is a small, porous, sealed bag or packet, typically containing tea leaves or the leaves of other herbs, which is immersed in water to steep and make an infusion. Originally used only for tea (''Camellia ...
s.


Market pulp

Market pulp is any variety of pulp that is produced in one location, dried and shipped to another location for further processing. Important quality parameters for pulp not directly related to the fibres are
brightness Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ...
, dirt levels, viscosity and ash content. In 2004 it accounted for about 55 million
metric tons The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States ...
of market pulp. Air dry pulp is the most common form to sell pulp. This is pulp dried to about 10 percent moisture content. It is normally delivered as sheeted bales of 250 kg. The reason to leave 10 percent moisture in the pulp is that this minimizes the fibre to fibre bonding and makes it easier to disperse the pulp in water for further processing to
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
. Roll pulp or ''reel pulp'' is the most common delivery form of pulp to non traditional pulp markets.
Fluff pulp Fluff pulp (also called comminution pulp or fluffy pulp) is a type of chemical pulp made from long fibre softwoods. Important parameters for fluff pulp are bulk and water absorbency. History Fluff pulp was first developed for use in disposable sani ...
is normally shipped on rolls (reels). This pulp is dried to 5–6 percent moisture content. At the customer this is going to a comminution process to prepare for further processing. Some pulps are flash dried. This is done by pressing the pulp to about 50 percent moisture content and then let it fall through
silo A silo (from the Greek σιρός – ''siros'', "pit for holding grain") is a structure for storing bulk materials. Silos are used in agriculture to store fermented feed known as silage, not to be confused with a grain bin, which is used t ...
s that are 15–17 m high. Gas fired hot air is the normal heat source. The temperature is well above the char point of
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
, but large amount of moisture in the fibre wall and lumen prevents the fibres from being incinerated. It is often not dried down to 10 percent moisture (air dry). The bales are not as densely packed as air dry pulp.


Environmental concerns

The major environmental impacts of producing wood pulp come from its impact on forest sources and from its waste products.


Forest resources

The impact of logging to provide the raw material for wood pulp is an area of intense debate. Modern
logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply chain ...
practices, using
forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management for ...
seek to provide a reliable, renewable source of raw materials for
pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or ful ...
s. The practice of
clear cutting Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with shelterwood and seed tree harvests, it is used by foresters to create certain types of forest ...
is a particularly sensitive issue since it is a very visible effect of
logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. Logging is the beginning of a supply chain ...
.
Reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Management A debate ...
, the planting of tree seedlings on logged areas, has also been criticized for decreasing
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
because reforested areas are
monocultures In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale ar ...
. Logging of
old growth forest An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...
s accounts for less than 10 percent of wood pulp, but is one of the most controversial issues.


Effluents from pulp mills

The process effluents are treated in a biological
effluent treatment plant Industrial wastewater treatment describes the processes used for treating wastewater that is produced by industries as an undesirable by-product. After treatment, the treated industrial wastewater (or effluent) may be reused or released to a sa ...
, which guarantees that the effluents are not toxic in the recipient. Mechanical pulp is not a major cause for environmental concern since most of the organic material is retained in the pulp, and the chemicals used (
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
and
sodium dithionite Sodium dithionite (also known as sodium hydrosulfite) is a white crystalline powder with a sulfurous odor. Although it is stable in dry air, it decomposes in hot water and in acid solutions. Structure The structure has been examined by Raman s ...
) produce benign byproducts (water and
sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 milli ...
(finally), respectively). Chemical pulp mills, especially kraft mills, are energy self-sufficient and very nearly closed cycle with respect to inorganic chemicals.
Bleaching Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...
with chlorine produces large amounts of
organochlorine An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalent bond, covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens subst ...
compounds, including polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs). Many mills have adopted alternatives to chlorinated bleaching agents thereby reducing emissions of organochlorine pollution.


Odor problems

The kraft pulping reaction in particular releases foul-smelling compounds. The hydrogen sulfide reagent that degrades lignin structure also causes some demethylation to produce
methanethiol Methanethiol (also known as methyl mercaptan) is an organosulfur compound with the chemical formula . It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood, brain and feces of animals (including hum ...
, dimethyl sulfide and
dimethyl disulfide Dimethyl disulfide (DMDS) is an organic chemical compound with the molecular formula which is the simplest disulfide. It is a flammable liquid with an unpleasant, garlic-like odor. Occurrence Dimethyl disulfide is a widespread natural odoriferou ...
. These same compounds are released during many forms of microbial decay, including the internal microbial action in Camembert cheese, although the kraft process is a chemical one and does not involve any microbial degradation. These compounds have extremely low odor thresholds and disagreeable smells.


Applications

The main applications for pulp are
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
and board production. The furnish of pulps used depends on the quality on the finished paper. Important quality parameters are wood furnish,
brightness Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ...
, viscosity, extractives, dirt count and strength. Chemical pulps are used for making
nanocellulose Nanocellulose is a term referring to nano-structured cellulose. This may be either cellulose nanocrystal (CNC or NCC), cellulose nanofibers (CNF) also called nanofibrillated cellulose (NFC), or bacterial nanocellulose, which refers to nano-struc ...
. Speciality pulp grades have many other applications.
Dissolving pulp Dissolving pulp, also called dissolving cellulose, is bleached wood pulp or cotton linters that has a high cellulose content (> 90%). It has special properties including a high level of brightness and uniform molecular-weight distribution. This pul ...
is used in making
regenerated cellulose Rayon is a semi-synthetic fiber, made from natural sources of regenerated cellulose, such as wood and related agricultural products. It has the same molecular structure as cellulose. It is also called viscose. Many types and grades of viscose ...
that is used
textile Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...
and
cellophane Cellophane is a thin, transparent sheet made of regenerated cellulose. Its low permeability to air, oils, greases, bacteria, and liquid water makes it useful for food packaging. Cellophane is highly permeable to water vapour, but may be coated w ...
production. It is also used to make
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
derivatives.
Fluff pulp Fluff pulp (also called comminution pulp or fluffy pulp) is a type of chemical pulp made from long fibre softwoods. Important parameters for fluff pulp are bulk and water absorbency. History Fluff pulp was first developed for use in disposable sani ...
is used in
diapers A diaper /ˈdaɪpə(r)/ (American and Canadian English) or a nappy (Australian English, British English, and Hiberno-English) is a type of underwear that allows the wearer to urinate or defecate without using a toilet, by absorbing or conta ...
,
feminine hygiene Feminine hygiene products are personal care products used during menstruation, vaginal discharge, and other bodily functions related to the vulva and vagina. Products that are used during menstruation may also be called menstrual hygiene produ ...
products and
nonwovens Nonwoven fabric is a fabric-like material made from staple fibre (short) and long fibres (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabri ...
.


Paper production

The Fourdrinier Machine is the basis for most modern
papermaking Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a speciali ...
, and it has been used in some variation since its conception. It accomplishes all the steps needed to transform pulp into a final
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
product.


Economics

In 2009,
NBSK Northern bleached softwood kraft (NBSK) is the paper industry's benchmark grade of pulp. Market NBSK is produced mainly in Canada and the Nordic countries. Some NBSK is also produced in north-western United States and in Russia. NBSK futures are ...
pulp sold for $650/ton in the United States. The price had dropped due to falling demand when newspapers reduced their size, in part, as a result of the recession.


See also

*
Nanocellulose Nanocellulose is a term referring to nano-structured cellulose. This may be either cellulose nanocrystal (CNC or NCC), cellulose nanofibers (CNF) also called nanofibrillated cellulose (NFC), or bacterial nanocellulose, which refers to nano-struc ...
*
Paper chemicals Paper chemicals designate a group of chemicals that are used for paper manufacturing, or modify the properties of paper. These chemicals can be used to alter the paper in many ways, including changing its color and brightness, or by increasing it ...
*
Pulp mill A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or ful ...
*
Pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gener ...
*
Versuche und Muster ohne alle Lumpen oder doch mit enem geringen Zusatze derselben Papier zu machen
' by Jacob Christian Schäffer on Google Books * Johan Richter, developer of the process for continuous cooking of pulp *
World Forestry Congress The World Forestry Congress (WFC) is the largest and most significant gathering of the world's forestry sector and it has been held every six years since 1926 under the auspices of the Food and Agriculture Organization (FAO) of the United Nations ...


References


Bibliography

* . {{DEFAULTSORT:Pulp (Paper) Wood products Papermaking Cellulose