Tall oil
Encyclopedia
Tall oil, also called "liquid rosin
" or tallol, is a viscous yellow-black odorous liquid obtained as a by-product
of the Kraft process
of wood pulp
manufacture when pulping mainly coniferous trees. The name originated as an anglicization of the Swedish
"tallolja" ("pine oil"). Tall oil is the third largest chemical by-product in a Kraft mill after lignin
and hemicellulose
; the yield of crude tall oil from the process is in the range of 30 – 50 kg / ton pulp. It may contribute to 1.0 - 1.5 % of the mill's revenue if not used internally.
and temperature
converts the esters and carboxylic acids in rosin into soluble sodium soap
s of lignin
, rosin
, and fatty acid
s. The spent cooking liquor is called weak black liquor
and is about 15 % dry content. The black liquor is concentrated in a multiple effect evaporator and after the first stage the black liquor is about 20 - 30 %. At this stage it is called intermediate liquor. Normally the soaps start to flotate
in the storage tank for the weak or intermediate liquors and is skimmed
off and collected. A good soap skimming operation reduces the soap content of the black liquor down to 0.2 - 0.4 % w/w of the dry residue. The collected soap is called raw rosin soap or rosinate. The raw rosin soap is then allowed to settle
or is centrifuge
d to release as much as possible of the entrained black liquor. The soap goes then to the acidulator where it is heated and acidified with sulfuric acid
to produce crude tall oil (CTO).
The soap skimming and acidulator operation can be improved by addition of flocculants. A flocculant will shorten the separation time and give a cleaner soap with lower viscosity. This makes the acidulator run smoother as well.
Most pines give a soap yield of 5 – 25 kg/ton pulp, while scots pine
gives 20 – 50 kg/ton. Scots pine grown in northern Scandinavia give a yield of even more than 50 kg/ton. Globally about 2 mill ton/year of CTO are refined.
. With pure pines
it is possible to have acid numbers in the range 160 - 165, while mills using a mix of softwoods and hardwoods in the furnish might give acid numbers in the range of 125 - 135.
Normally crude tall oil contains rosin
s, unsaponifiable
sterol
s (5-10%), resin acid
s (mainly abietic acid
and its isomer
s), fatty acid
s (mainly palmitic acid
, oleic acid
and linoleic acid
), fatty alcohol
s, some sterol
s, and other alkyl hydrocarbon
derivates.
By fractional distillation
tall oil rosin is obtained, with rosin content reduced to 10-35%. By further reduction of the rosin content to 1-10%, tall oil fatty acid (TOFA) can be obtained, which is cheap, consists mostly of oleic acid
, and is a source of volatile fatty acids.
s, rubber
s, and ink
s, and as an emulsifier. The pitch
is used as a binder
in cement, an adhesive, and an emulsifier for asphalt
.
TOFA is a low-cost and vegetarian lifestyle-friendly alternative to tallow
fatty acids for production of soap
s and lubricant
s. When esterified with pentaerythritol
, it is used as a compound of adhesive
s and oil-based varnish
es.
Tall oil is also used in oil drills as a component of drilling fluid
s.
Rosin
.Rosin, also called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black...
" or tallol, is a viscous yellow-black odorous liquid obtained as a by-product
By-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....
of the Kraft process
Kraft process
The kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
of wood pulp
Wood pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
manufacture when pulping mainly coniferous trees. The name originated as an anglicization of the Swedish
Swedish language
Swedish is a North Germanic language, spoken by approximately 10 million people, predominantly in Sweden and parts of Finland, especially along its coast and on the Åland islands. It is largely mutually intelligible with Norwegian and Danish...
"tallolja" ("pine oil"). Tall oil is the third largest chemical by-product in a Kraft mill after lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
and hemicellulose
Hemicellulose
A hemicellulose is any of several heteropolymers , such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength...
; the yield of crude tall oil from the process is in the range of 30 – 50 kg / ton pulp. It may contribute to 1.0 - 1.5 % of the mill's revenue if not used internally.
Manufacturing
In the Kraft Process, high alkalinityAlkalinity
Alkalinity or AT measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. The alkalinity is equal to the stoichiometric sum of the bases in solution...
and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
converts the esters and carboxylic acids in rosin into soluble sodium soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
s of lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
, rosin
Rosin
.Rosin, also called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black...
, and fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s. The spent cooking liquor is called weak black liquor
Black liquor
Black liquor is the spent cooking liquor from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers....
and is about 15 % dry content. The black liquor is concentrated in a multiple effect evaporator and after the first stage the black liquor is about 20 - 30 %. At this stage it is called intermediate liquor. Normally the soaps start to flotate
Flotation process
Flotation process is a method of separation widely used in the wastewater treatment and mineral processing industries.Various flotation processes include the following:* Dissolved air flotation...
in the storage tank for the weak or intermediate liquors and is skimmed
Skimmer (machine)
An oil skimmer is a machine that separates a liquid from particles floating on it or from another liquid. A common application is removing oil floating on water. These technologies are commonly used for oil spill remediation but are also commonly found in industry...
off and collected. A good soap skimming operation reduces the soap content of the black liquor down to 0.2 - 0.4 % w/w of the dry residue. The collected soap is called raw rosin soap or rosinate. The raw rosin soap is then allowed to settle
Settling
Settling is the process by which particulates settle to the bottom of a liquid and form a sediment. Particles that experience a force, either due to gravity or due to centrifugal motion will tend to move in a uniform manner in the direction exerted by that force...
or is centrifuge
Centrifuge
A centrifuge is a piece of equipment, generally driven by an electric motor , that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis...
d to release as much as possible of the entrained black liquor. The soap goes then to the acidulator where it is heated and acidified with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
to produce crude tall oil (CTO).
The soap skimming and acidulator operation can be improved by addition of flocculants. A flocculant will shorten the separation time and give a cleaner soap with lower viscosity. This makes the acidulator run smoother as well.
Most pines give a soap yield of 5 – 25 kg/ton pulp, while scots pine
Scots Pine
Pinus sylvestris, commonly known as the Scots Pine, is a species of pine native to Europe and Asia, ranging from Scotland, Ireland and Portugal in the west, east to eastern Siberia, south to the Caucasus Mountains, and as far north as well inside the Arctic Circle in Scandinavia...
gives 20 – 50 kg/ton. Scots pine grown in northern Scandinavia give a yield of even more than 50 kg/ton. Globally about 2 mill ton/year of CTO are refined.
Composition
The composition of crude tall oil varies a lot, depending on the wood furnish used. A common quality measure for tall oil is acid numberAcid number
In chemistry, acid value is the mass of potassium hydroxide in milligrams that is required to neutralize one gram of chemical substance. The acid number is a measure of the amount of carboxylic acid groups in a chemical compound, such as a fatty acid, or in a mixture of compounds...
. With pure pines
Pines
Pines may refer to:*Pine, coniferous trees of the genus Pinus, in the family Pinaceae*PINES or Public Information Network for Electronic Services- People with the surname :...
it is possible to have acid numbers in the range 160 - 165, while mills using a mix of softwoods and hardwoods in the furnish might give acid numbers in the range of 125 - 135.
Normally crude tall oil contains rosin
Rosin
.Rosin, also called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black...
s, unsaponifiable
Unsaponifiable
Unsaponifiables are components of an oily mixture that fail to form soaps when blended with lye. Since saponifiable components of the original oil mixture do form soaps, the result of a soap making procedure is a mixture of soaps and other, frequently oily, materials.Unsaponifiable constituents...
sterol
Sterol
Sterols, also known as steroid alcohols, are a subgroup of the steroids and an important class of organic molecules. They occur naturally in plants, animals, and fungi, with the most familiar type of animal sterol being cholesterol...
s (5-10%), resin acid
Resin acid
Resin acids usually refers to mixtures primarily. Abietic acid is the main component but several related carboxylic acids. Nearly all resin acids have the same basic skeleton: three fused ring fused with the empirical formula C19H29COOH. These materials occur in rosin but also occur in fossil...
s (mainly abietic acid
Abietic acid
Abietic acid , an organic compound that occurs widely in trees. It is the primary component of resin acid, is the primary irritant in pine wood and resin, isolated from rosin and is the most abundant of several closely related organic acids that constitute most of rosin, the solid portion of the...
and its isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
s), fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s (mainly palmitic acid
Palmitic acid
Palmitic acid, or hexadecanoic acid in IUPAC nomenclature, is one of the most common saturated fatty acids found in animals and plants. Its molecular formula is CH314CO2H. As its name indicates, it is a major component of the oil from palm trees . Palmitate is a term for the salts and esters of...
, oleic acid
Oleic acid
Oleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable fats. It has the formula CH37CH=CH7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid...
and linoleic acid
Linoleic acid
Linoleic acid is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2...
), fatty alcohol
Fatty alcohol
Fatty alcohols are aliphatic alcohols consisting of a chain of 8 to 22 carbon atoms. Fatty alcohols usually have even number of carbon atoms and a single alcohol group attached to the terminal carbon. Some are unsaturated and some are branched...
s, some sterol
Sterol
Sterols, also known as steroid alcohols, are a subgroup of the steroids and an important class of organic molecules. They occur naturally in plants, animals, and fungi, with the most familiar type of animal sterol being cholesterol...
s, and other alkyl hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
derivates.
By fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...
tall oil rosin is obtained, with rosin content reduced to 10-35%. By further reduction of the rosin content to 1-10%, tall oil fatty acid (TOFA) can be obtained, which is cheap, consists mostly of oleic acid
Oleic acid
Oleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable fats. It has the formula CH37CH=CH7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid...
, and is a source of volatile fatty acids.
Applications
The tall oil rosin finds use as a component of adhesiveAdhesive
An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
s, rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
s, and ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
s, and as an emulsifier. The pitch
Pitch (resin)
Pitch is the name for any of a number of viscoelastic, solid polymers. Pitch can be made from petroleum products or plants. Petroleum-derived pitch is also called bitumen. Pitch produced from plants is also known as resin. Products made from plant resin are also known as rosin.Pitch was...
is used as a binder
Binder (material)
-See also:*Adhesive or Glue*Cement*Paint...
in cement, an adhesive, and an emulsifier for asphalt
Asphalt
Asphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...
.
TOFA is a low-cost and vegetarian lifestyle-friendly alternative to tallow
Tallow
Tallow is a rendered form of beef or mutton fat, processed from suet. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.In industry,...
fatty acids for production of soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
s and lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
s. When esterified with pentaerythritol
Pentaerythritol
Pentaerythritol is the organic compound with the formula C5H12O4. This white, crystalline polyol with the neopentane backbone is a versatile building block for the preparation of many polyfunctionalized compounds such as the explosive PETN and pentaerythritol tetraacrylate...
, it is used as a compound of adhesive
Adhesive
An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
s and oil-based varnish
Varnish
Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss...
es.
Tall oil is also used in oil drills as a component of drilling fluid
Drilling fluid
In geotechnical engineering, drilling fluid is a fluid used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid...
s.