Tall oil

Source: Wikipedia, the free encyclopedia.

Tall oil, also called liquid rosin or tallol, is a viscous yellow-black odorous liquid obtained as a

coniferous trees.[1][2] The name originated as an anglicization of the Swedish tallolja ('pine oil').[3] 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.[4]
It may contribute to 1.0–1.5% of the mill's revenue if not used internally.

Manufacturing

Forchem tall oil refinery in Rauma, Finland

In the kraft process, high

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 centrifuged 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).[citation needed
]

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.[citation needed
]

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.[2]

Composition

See also: Resin acid

The composition of crude tall oil varies a great deal, depending on the type of wood used. A common quality measure for tall oil is

acid number. With pure pines it is possible to have acid numbers in the range 160–165, while mills using a mix of softwoods and hardwoods might give acid numbers in the range of 125–135.[2]

Normally crude tall oil contains

alkyl hydrocarbon derivates.[3]

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.[citation needed]

Applications

The tall oil rosin finds use as a component of

emulsifier for asphalt.[citation needed][5]

TOFA is a low-cost and

epoxy resin curing agents.[6]

References

  1. ISBN 978-3527306732
    .
  2. ^
    ISBN 952-5216-06-3.{{cite book}}: CS1 maint: location missing publisher (link
    )
  3. ^
    ISBN 0-12-097360-X
    .
  4. ISBN 952-5216-03-9.{{cite book}}: CS1 maint: location missing publisher (link
    )
  5. ^ "TALL OIL PITCH AS BITUMEN EXTENDER" (PDF). {{cite journal}}: Cite journal requires |journal= (help)
  6. ^ "Hexion Amidoamine epoxy curing agents".
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