Tall oil, a by-product of kraft pulping of pine wood, is formed by acidifying black liquor soap skimmings. It consists of resin acids or rosin, fatty acids, and neutrals. Crude tall oil is an excellent source of rosin and tall oil fatty acid, an industrial-grade oleic and linoleic acid blend. The bulk of the neutrals, largely esters of fatty acids, sterols, resin and wax alcohols, and hydrocarbons, boil at either lower or higher temperatures than the boiling range of the fatty and resin acids.
Tall oil itself has a variety of uses in industry. It is used as a frothing agent in the flotation process for reclaiming low grade copper- lead- and zinc-bearing ores, and as a solvent or wetting agent in a variety of textile and synthetic fibre manufacturing processes. The distilled fatty acids are used in soaps, detergents and disinfectants and as a base for lubricating greases, textile oils, cutting oils and metal polishes. They are also used as drying agents in paint, although synthetic substances are widely used. The fatty acids are unsaturated and on exposure to air undergo autoxidation and polymerization to form resin-like materials which form a tough protective coating. Resin acids are used in rubber polymerization and compounding, as size to impart water resistance to paper, and in adhesives and printing inks. Resin acids are the major component of a substance known as rosin, which is used by musicians to improve the grip of bows used for string instruments.
The book contains production details of different products like recovery of crude tall oil, Composition and properties of crude tall oil, Lab. Scale fractional vacuum distillation, tall oil soap acidulation, purification of sulphate soap, hydrodynamic separation of CTO, dimerization of tall oil fatty acid, black liquor soap recovery methods, tall oil in asphalt products and petroleum uses, tall oil in liquid soaps, tall oil in rubber, paper and printing inks etc. This book is very useful for scientists, scholars, consultants and technical institutions.
1. INTRODUCTION
Introduction to Tall Oil
History of Tall Oil
Production Process for Tall Oil
Recovery of Tall Oil
Composition and Properties of Tall Oil
Crude Tall Oil
Analysis and Testing of Tall Oil Products
Applications of Tall Oil
2. RECOVERY OF TALL OIL
The Chemistry of Tall Oil Fatty and Rosin Acids
Chemical Composition of Tall Oil Fatty Acids
General Reactions of Tall Oil Fatty Acids
Reactions Involving the Carboxyl Group
Chemical Composition of Tall Oil Rosin
Dimer Acids Manufacture and Feedstock
3. COMPOSITION AND PROPERTIES OF CRUDE
TALL OIL
Tall Oil Production and Laboratory Analyses at the Factories
Studies on the Precursors of Indian Tall Oil
Analytical Studies on the Composition of Crude Tall Oil
Experimental
Testing of Tall Oil with Standard Methods
Fractionation of Samples
Crude Tall Oil Recovery from Sulfate Soap
Separation of Free Acids and Neutrals
Preferential Esterification
Saponification
Methylation and Silylation
Thin-Layer Chromatography (TLC)
Preparative Argentation TLC
Gas Chromatography (GC)
Gas Chromatography—Mass Spectrometry (GC-MS)
Results and Discussion
Testing of Tall Oil with Standard Methods
Group Fractionations
Studies on the Composition and Component Distribution
Fatty Acids
Saturated Fatty Acids
Monoenoic Fatty Acids
Dienoic Fatty Acids
Trienoic Fatty Acids
Tetraenoic Fatty Acids
Conjugated Fatty Acids
Esterified Acids
Resin Acids
Neutral Components
Gr. 1 Phytosterols
Gr. 2 Monoterpene alcohols
Diterpene Abietic and Pimaric Type Alcohols
Fatty Alcohols
Triterpene Alcohols
Gr. 3
Gr. 4
Gr. 5
Gr. 6 Oxosteroids
Gr. 7 Dimethoxy Stilbenes
Gr. 8 Resin Acid Methyl Esters
Gr 9 Diterpene Aldehydes
Gr. 10 Esters of Fatty Acids with Diterpene Alcohols
Gr. 11 Esters of Fatty Acids with Fatty Alcohols
Gr. 12 Esters of Fatty Acids with Sterols and Triterpene Alcohols
Gr. 13 Hydrocarbons
Sesquiterpene Hydrocarbons
Diterpene Hydrocarbons
Typical Features of Indian Tall OIl
General Properties
Component Distribution
Factors Influencing the Properties ond Composition of Crude Tall Oil
Wood Species
Geographical Location (Climate)
Roundwood and Chip Storage
Other Factors
4. CHEMICAL CHANGES DURING STORAGE OF
CRUDE TALL OIL
Experimental
Results and Discussion
Drop in Acid Number
Esterification
Thermal and Acid Isomerization of Resin Acids
General
Results from Laboratory Storage
Crystallization
Changes in the Composition of Conjugated Fatty Acids
Aspects of the Storage of Turkish Crude Tall Oil
5. LABORATORY-SCALE FRACTIONAL VACUUM
DISTILLATION
Experimental
Still
Charges
Procedure
Analytical Procedures
Results and Discussion
Composition of the Distillates
Distribution of Tall Oil Constituents in the Distillates
Fatty Acids
Esterified Acids
Resin Acids
Neutrals
Sesquiterpene Hydrocarbons
Diterpene Hydrocarbons
Hydrocarbons from Decarboxylation of Resin Acids
Diterpene Aldehydes
Pinosylvin Dimethyl Ether
Diterpene Alcohols
Resin Acid Methyl Esters
Fatty Alcohols
Dehydrated Sterols
Sterols
Triterpene Alcohols
Esters
Unidentified Components
Composition of the Pitches
Components Not Eluted on GC
Volatilities of Tall Oil Constituents with Special Reference to Fatty and Resin Acids
General
Observations on the Laboratory Distillation
Brief Critique on the Laboratory Distillation
Conclusions
6. OZONOLYSIS AND EPOXIDATION OF METHYL
MALEOPIMARATE
Results and Discussion
Ozonolysis and Epoxidation of Methyl Maleopimarate (lb) and Other Related Compounds
Structural Assignment to 4a
Absolute Configuration of 4b
Structure of the Anhydride 6
Structure of the Epoxy Anhydride 5
Reaction of Peroxytrifluoroacetic with Bicyclo[2.2.2]oct-5-ene-endo-cis-2.3-dicarboxylic Anhydride (8)
Structural Assignment to 9
Structure of the Hydroxy Lactone 10
Experimental
Ozonolysis of Methyl Maleopinarate (lb). Isolation of 4b, 5, and 6
Preparation of the Tetramethyl Ester of 6
Preparation of 5 by Direct Epoxidation of lb
Preparation of 20
Reaction of 21 with Peroxytrifluoroacetic Acid. Preparation of 22
Reaction of Peroxvtrifluoroacetic Acid with Olefin 8. Preparation of 5,6-Endo-epoxy-bicyclo[2.2.2]octane-cis-2,3-dicarboxylie Anydride 9
Epoxidation of Olefin 8 with m-Chloroperbenzoic Acid. Preparation of Hydroxy Lactone 10
Preparation of 35 and 36 from 10
Preparation of 37 and 38
Preparation of Bromo Lactonic Acid 39 from the Olefinic Anhydride 8
Preparation of the Bromohydrin 41 of Dimethyl Ester 37
Preparation of 40, the C2 Epimer of 39
Discussion of Results
The Benzogulnone Adduct of Levopimaric Acid (XXVIII)
The Dimethyl Acetylenedlcarboxylate Adduct of Levopinaric Acid
Other Adducts of Levoplmarlc Acid
7. TALL OIL SOAP ACIDULATION
Batch Process
Semi-Batch Process
Continuous Decanting Process
Centrifuge Process
8. RETROFITTING A TALL OIL ACIDULATION
PLANT
9. PURIFICATION OF SULPHATE SOAP
10. HYDRODYNAMIC SEPARATION OF CTO
11. REFINING OF TALL OIL BY COLUMN LIQUID-
LIQUID EXTRACTION
Introduction
The Pilot Plant at the Technical Research Centre of Finland
Trials with Mixed Pine-Birch Soap
Trials with Other Tall Oil Products
Conclusions
12. DIMERIZATION OF TALL OIL FATTY ACID
13. TALL OIL SOAP ACIDULATION AND SULFUR
BALANCE PROBLEMS IN KRAFT MILLS
Soap Acidulation
Spent Acid Disposal
Sulfur Losses
Soda Losses
Sulfur Balance
Replace H2SO4 with DGE
Sewering DGE
Modified C102 Production Technology
Concluding Remarks
14. BLACK LIQUOR SOAP RECOVERY METHODS
Woodstorage
Digestion and Washing
Soap Recovery in the Weak Liquor System
Soak Skimmer Design and Operation
Air Injection to Improve Recovery
Influence of Hardwood Liquor on Soap Recovery
Heavy Liquor Soap Recovery
Soap Decanter Design and Operation
Monitoring Soap Recovery Efficiency
Summary
15. CONTROLLING POLLUTION IN A LUWA TALL
OIL DISTILLATION PLANT
Sources of Effluents from CTO Facilities
Processes for the Distillation of Crude Tall Oil
The Luwa CTO Distillation Process
Effluents from the Luwa CTO Distillation Process
Minimizing Effluents in CTO Distillation Plants
16. ADVANCED POLLUTION CONTROL TECHNOLOGY
IN THE STEAM DISTILLATION OF TALL OIL
Corrosion & Materials of Construction
Reboiler Design
Tower Internals
Stability
Conclusion
17. NEW SEPARATION TECHNOLOGY FOR
DISTILLED TALL OIL
Introduction
Sorbex Process Outline
Simulated Moving Bed
Experimental Results
Conclusions
18. CARBON DIOXIDE PROCESS
Introduction
Discussion
19. FINNISH EXPERIENCE IN TALL OIL PITCH AS
ASPHALT SUBSTITUTE
Background
Tall Oil Pitch - Renewable Natural Resource
Pitches in Asphalt and Pavement Characteristics
Mixing and Laying of the Pavements in Field Experiments
Wear Tests in Laboratory and On Field Show Improved Tendency
Asphalt Paving Contracts in 1988
Prejudices Disappear -The Future Is Open
20. USES OF TALL OIL
Tall Oil Products in Surface Coatings
Tall Oil in Alkyd Resins
Tall Oil Formulations in Alkyd Resins
Short Oil Baking Alkyd - Solvent Process
Properties
Short Oil Baking Alkyd - Fusion Process
Medium Oil Alkyd-Fusion Process
Long Oil Alkyd - Fusion Process
Rosin Modified Allkyd-Fusion Process
Glycerine Ester
Maleic Modified Ester
Distilled Tall Oil Epoxy Ester
Other Uses for Tall Oil Products
Tall Oil in the Plasticizer Field
Tall Oil Plasticizers
Esterification of Tall Oil for Plasticizers
Tall Oil in Adhesives and Linoleum Cement
Tall Oil in Rubber Based Adhesives
Tall Oil in Hot-Melt Adhesives
Tall Oil Products in Linoleum Cements
21. TALL OIL IN ASPHALT PRODUCTS AND
PETROLEUM USES
Tall Oil in Asphalt
Roads
Soil Treatments
Roofing
Adhesives
Antistripping Agents
Plasticizers
Miscellaneous
Tall Oil in Petroleum Applications
Oil and Gas Well Fracturing
Drilling Muds
Demulsification Agents
Corrosion Inhibitors
Catalyst
Lubricating Oil Additives
22. TALL OIL IN LIQUID SOAPS
Tall Oil in Disinfectants
Tall Oil in Synthetic Detergents and Wetting Agents
Syndet Types
Syndet Products
Tall Oil in Biodegradable Detergents
23. TALL OIL IN FLOTATION COLLECTORS AND
CORE OILS
Tall Oil in Flotation Collectors
Flotation Collectors
Flotation Applications
Tall Oil in Core Oils
24. TALL OIL IN RUBBER
Styrene-Butadiene Rubber
Cold SBR Formulation (SBR 1500 Series)
Hot SBR Formulation (SBR 1000 Series)
Cold High Solids SBR 2105 Latex Formulation (SBR 2100 Series)
Hot SBR Latex Formulation (SBR 2000 Series Type II)
Foam Rubber
25. TALL OIL IN PAPER SIZE
Papermaking Process
Rosin Sizing Materials
Forms of Size Available
Paste Size
Dry Size
Methods of Preparing Liquid Size
Cooking Process
Emulsion Process
Bewoid Process
Delthirna Process
Internal and External Sizing
Effect of Wet Strength Resins and Paper Coating Resins on Sizing
Sizing of Nonconventional Paper
Testing of Sizing
Water Resistance of Paper and Paperboard—T433 M-44 (Dry Indicator Method)
Water Immersion Test of Paperboard—T491 SU-63
Water Absorption of Paperboard—T492 SM-60
Water Absorptiveness of Nonbibulous Paper and Paperboard— T441M-60 (Cobb Test)
Degree of Curl and Sizing of Paper—T466 M-52
Ink Penetration Test
Fotosize Penetration Test—Lactic Acid Test
26. TALL OIL IN PRINTING INK
Typographic Printing and Typographic Inks
Heat-Set Inks
Steam-Set Inks
Newsprint Inks
Lithographic Printing and Lithographic Inks
Intaglio or Gravure Printing and Gravure Inks
Silk-Screen Printing Inks
Overprint Varnishes
Bag Inks
27. MISCELLANEOUS APPLICATIONS OF TALL OIL
Tall Oil Fatty Acids for Chemical Intermediates
Polymerized Fatty Acids
Azelaic and Pelargonic Acids
Tall Oil in Coprecipitated Barium Salts
Tall Oil in Defoamers
TALL OIL IN PIGMENT DISPERSANTS
^ Top
Recovery of Tall Oil
The
Chemistry of Tall Oil Fatty
and Rosin Acids
Fatty acids
and rosin acids are large and important groups of organic acids
occuring in
nature-the fatty acids usually in combination with glycerol or sterols
in the
form of esters. During the kraft process of making pulp, most of the
esters
present in the wood are saponified with the formation of soaps of
sodium salts
of the fatty and rosin acids. Acidulation of these soaps yields crude
tall oil,
from which fatty acids and rosins are obtained by fractional
distillation.
Chemical
Composition of Tall Oil
Fatty Acids
Tall oil
fatty acids are compound of carbon, hydrogen, and oxygen. The carbon
atoms are
linked together in the fatty acid molecule in the form of a long chain.
At one
end of the chain is an acidic or carboxyl group (—COOH) which
characterizes all
carboxylic acids, both aliphatic and aromatic. Practically of the fatty
acids
present in crude tall oil have a straight chain and contain an even
number of
carbon atoms. However, small amounts of branched-chain and odd-numbered
acids
have recently been reported. The tall oil fatty acids consist chiefly
of oleic
and linoleic acids. Palmitic acid, which is the main componenty of the
saturated fatty acids in tall oil, is almost completely removed as a
heads products
in the fractionation process. Rosin acids present in crude tall oil are
almost
completely absent in high grade tall oil fatty acids. Higher molecular
weight
fatty acids also present in crude tall oil are removed in the pitch
fraction.
The typical composition of tall oil fatty acids is given in Table 1.
The
physical properties of the major tall oil fatty acids are given in
Table 2. The
neutral material in tall oil fatty acids consists mainly of
dimethoxystilbene
and abietene type hydrocarbons, which are essentially free of
functional
groups.
Dimer
Acids Manufacture and
Feedstock
In
present-day commercial
practice, dimer acids are prepared by the thermal condensation of
unsaturated
fatty acids, usually catalyzed by small amounts of montmorillonite
clay. These
manufacturing procedures are described in a number of patents, like
detail the
effect of reaction temperatures, pressures, clay content and type and
other
reaction variables. Another, and overwhelmingly important, variable is
the
unsaturated fatty acid used as feedstock for dimer production. The
published
literature describes the use of starting materials (both free fatty
acids and
alkyl esters) which are rich in polyunsaturates such as those derived
from
drying and semi-drying vegetable and marine oils linoleic and linolenic
acid
and their higher-molecular-weight homologues. The literature also
describes the
use of monounsaturated fatty acids such as oleic acid and its isomers,
erucic
acid, undecylenic acid, and other monounsaturated fatty acids. The
principal
feedstock for production of dimer acids, from the outset of commercial
production, has been tall oil fatty acids, the cheapest unsaturated
fatty acid
available. This raw material is produced by the high-vacuum
fractionation of
tall oil, which, is the generic name for the products derived from the
black
liquor residue of the kraft pulping process. A typical analysis of
commercial
grade tall oil shown in Table 3.
Carbon Dioxide Process
Introduction
A major
source of sulfur in kraft mills that have crude tall oil acidification
plants
is the sodium sulfate brine. As kraft mills reduce their emissions,
less sulfur
is lost, and the sulfur input to the kraft mill must be reduced to
maintain
targeted sulfidity levels. The carbon dioxide process was developed as
an
approach to reducing the sulfate brine generated by the crude tall oil
acidification plant. A pilot plant was constructed and run continuously
for two
weeks in 1975 to demonstrate the process. This initial work and
subsequent work
done in the laboratory and pilot plant at Westvaco form the basis of
this
paper.
Discussion
Chemistry.
In sulfuric acid
acidification, the tall oil soap is converted to crude tall oil (CTO)
via an
essentially irreversible and quantitative reaction:
2 RCOO–Na+
+ H2SO4
®
2 RCOOH
+ Na2SO4
(1)
CTO Soap Sulfuric
CTO
Sodium
Acid
Sulfate
In the carbon
dioxide process, the inorganic acid is carbonic acid formed by the
reversible
reaction of carbon dioxide and water:
CO2 + H2O H2CO3
(2)
Carbon Water
Carbonic
Dioxide
Acid
The process
flows for a plant which would produce 100 tons of CTO per day are shown
in
Table 1. These flows are based upon 40% replacement of the inorganic
acid in a
normal sulfuric acid process with carbon dioxide. The low-solids sodium
bicarbonate stream is significant and is discussed later.
The major
costs and savings of implementing the carbon dioxide process on an
existing
sulfuric acid process are listed in Table 2. The cost of purchased
carbon
dioxide could be reduced substantially by installing an absorption
process to
recover carbon dioxide from lime kiln stacks, but this would increase
capital
cost and increase the operating complexity. Carbon dioxide application
will
reduce the sulfuric acid consumption by at least 40% and also reduce
the sodium
hydroxide required to neutralize the sulfate brine by at least 40%
since the
sulfate brine stream is reduced proportionally. The extra dilution
water
contained in the bicarbonate brine must be evaporated if the sodium is
to be
retained in the kraft system; alternatively the bicarbonate brine may
replace
an existing water stream in the kraft system as discussed below and not
add
cost to the process. The capital required for a system shown in Figure
2
capable of producing 100 tons of CTO per day is estimated to be $1.5
million,
although this would vary significantly with the preparation, tankage
and piping
required at each individual site. The depreciation of this capital is a
significant fraction of the costs as shown in Table 2. The assumption
is made
that the operator running the crude plant could operate the carbon
dioxide
process and that no extra labor is required. Electricity and steam
costs of
running the plant are small and are not included in Table 2.
As shown in
Table 2, the incremental cost of a carbon dioxide process is relatively
low;
the process would not be implemented unless changes were mandated as a
result
of the sulfidity levels being too high in a kraft system. When compared
to
other alternatives such as dumping sulfate into the waste treatment
system and
not recovering the sodium, the incremental cost of the carbon dioxide
system is
favorable.
Bicarbonate Brine
Disposition.
A problem which must be
addressed before a carbon dioxide process can be implemented is finding
a
“home” for the dilute sodium bicarbonate brine stream. Two alternatives
that
have been considered are shown in figure 3. The bicarbonate brine could
displace wash water in the lime mud washing system. The sodium thus
would be
recovered in the white liquor. But washing efficiency and foaming
tendency from
dissolved organics are concerns which must be assessed. However, the
level of
these organics is very low, and no foaming tendency has been noticed in
laboratory and pilot work. A second alternative is to put the
bicarbonate brine
directly into the dissolving tank for the smelt where foam would not be
a
concern. Neither alternative is envisioned to benefit the operation to
which
the bicarbonate brine is added; the overall benefit would be keeping
sodium in
the kraft mill system.
Black Liquor Soap
Recovery Methods
The recovery
of black liquor, and the conversion and the sale of the tall oil
products make
a significant contribution to the profitability of mill sites for Union
Camp
Corporation. This discussion will concern itself with recovery methods
at
southern kraft pulp mills in Savannah, Georgia and Montgomery, Alabama.
Woodstorage
At both mills
a relatively small wood inventory is maintained. Roundwood is
inventoried in
the field, and tall oil losses during storage are limited to less than
about
10% as estimated by Cowart, Tate, and Churchill. The mills maintain
wood
inventories primarily in outside chip storage facilities. Additional
tall oil
losses resulting from outside chip storage are less than 1% as per
Thornburg.
Chips are removed from the pile on a last in, first out basis as per
Springer.
Digestion
and Washing
In Savannah
the pulp is washed on drum washers. Soap losses on the washers vary
from eight
to twelve pounds per air dry ton of pulp produced. There is no attempt
made to
segregate the liquors of the different species of pulps prior to
evaporation to
improve soap recovery. No semi-chemical hardwood pulp is currently
produced in
Savannah.
In Montgomery
hardwood and pine liquors are evaporated separately so that in the
event that
semi-chemical pulp is produced in the hardwood digesters, soap losses
could be
minimized.
Soap
Recovery in the Weak Liquor
System
In Savannah,
the wash plant weak liquor is filtered and drops into the first of
several weak
liquor storage tanks placed in series. The foam produced is directed
through a
Lundberg Foam Concentrator and the concentrated (broken) foam is then
directed
to a tall foam tower in which the weight of the broken foam is used to
densify
it. This densified broken foam is then directed to the soap decanter
where the
broken foam and the liquor separate. The density of the broken foam
varies from
3 to 5.5 lbs./gallon. The other tanks in the series are soaped once to
twice
per week by filling the tanks and overflowing the soap through the
broken foam
system to the soap decanter. Approximately 25% of the total mill soap
recovery
is accomplished in this manner.
In the
Montgomery, Alabama mill the filtered weak liquor is directed to weak
liquor
tanks for each of the evaporator trains. These weak liquor tanks
operate in
parallel. The weak liquor tanks are soaped daily by overflowing the
soap and
foam into an inverted cone collector. This soap and foam is then sent
to the
soap decanter where the liquor is drained off. The solids content of
the liquor
being fed to weak liquor storage from the washers is 14 to 15%. Heavy
liquor
from the evaporator discharge is recirculated to increase the feed
solids to
the evaporator.
Soak
Skimmer Design and
Operation
Principle
of Operation — Stokes’ Law: For soap
recovery by gravity separation, as occurs in skim
tanks, the soap particles must agglomerate into particles considerably
larger
than micelles as reported by Pon’ Kina. However these particles
agglomerate
rapidly as was reported by Bolger and Hopfenberg and that on standing
for a
short while, the agglomerates normally have rise velocities of about 5
to 20
feet per hour. The agglomerated soap particles separate from the black
liquor
according to Stokes. Since Stokes’ Law only applies in the laminar flow
regime
at Reynold’s numbers less than 1 it is necessary that turbulence in a
skim tank
be avoided if at all possible. Downward flow conditions should also be
minimized.
Further
consideration of the Stokes’ Law equation indicates that by increasing
the
density of the black liquor through increased solids, the rise rate
should be
increased. By decreasing the density of the soap particles such as
through air
injection the rise rate may be increased. Increasing the particle
diameter size
could occur as a result of agglomeration resulting from increased
settling
time, and also air injection or perhaps by chemical additives to
agglomerate
the particles. Decreasing the viscosity of the liquor through
increasing the
liquor temperature should assist the particles to separate. However,
viscosity
is increased by increased solids at a given temperature and therefore a
minimum
solubility exists in the region of 22 to 28% solids.
As is
indicated in Table 1, all of Union Camp’s soap skimmers operate in this
region.
Studies have been carried out on our No. 7 Soap Skimmer in Savannah
where the
feed solids to the soap skimmer were changed from 22% to 27% in the
liquor
feed, however, no appreciable change in tall oil residual content of
the
skimmed liquor was observed. This is not surprising since the studies
performed
to determine the effect of liquor solids on soap solubility were
performed
under static conditions and the turbulence generated in an operating
soap
skimmer would be such that liquor density effects would be negated.
Furthermore, the difference between liquor density and soap density
increased
about 33% but this was largely offset by a 30% increase in liquor
viscosity.
Skim Tank
Design: As has been
pointed out by Dusenbury the design of a soap skimmer should be based
upon the
rise rate of the soap in that skimmer. In the Savannah Mill, the soap
rise
rates have been measured to be in excess of 80 feet per hour. Although
these
rise rates are much in excess of those normally reported, it would
appear that
they also vary widely in the absence of air injection and therefore may
explain
wide variations in soap skimmer performance. Despite these very high
soap rise
rates. No. 7 Skimmer has shown very poor soap recovery unless assisted
by air
flotation. The reason for this poor performance is skim tank design.
No. 7 Soak
Skimmer is very deep and tends to be rather turbulent. Much of this
turbulence
is related to its circular shape.
Of the eight
skim tanks operating in the Savannah and Montgomery mills, four of the
skimmers
are rectangular in shape and four of the skimmers are circular in
shape. The
rectangular skimmers as a whole have a much smaller residence time than
the
circular skimmers, however, their performance in the absence of air
injection
is as good as or better than the performance of two of the circular
skimmers.
The most efficient skimmer is No. 3 Skimmer in Montgomery which is a
circular
skimmer. It is effective in that it essentially models a rectangular
soap
skimmer by the use of a spiral baffling arrangement.
Skim Tank
Baffling: The
baffling arrangement has been found to be very important in skim tank
operation
because of its effect on turbulence and soap particle “short
circuiting.” This
is evidenced by the performance of No. 4 and No. 5 Skimmers in
Savannah. With
reference to Table 1, it is apparent that both skimmers although they
are
similar in size, shape, and liquor residence time, the increased
turbulence
caused by the baffling in No. 4 Skimmer results in a higher product
liquor tall
oil residual than No. 5 Skimmer. The baffling on No. 4 Soap Skimmer
creates an
over and under flow pattern and results in excessive turbulence which
reduces
the efficiency of the skimmer.
No. 7 Skimmer
in Savannah is a circular skimmer. It was originally baffled as shown
in Figure
1A. No. 7 Skimmer experienced very poor performance as evidenced by
high outlet
tall oil residuals in the product liquor and this was due to excessive
turbulence generated by the baffles. By replacing the baffles with a
single
mid-feather baffle, as in Figure 1B, the tall oil residuals in the
product
liquor were reduced.
The No. 1
Circular Skimmer in the Montgomery, Alabama Mill is inefficient for its
size.
This skimmer is concentrically baffled as in Figure 1A and this
baffling also
tends to produce excessive turbulence and therefore soap particle short
circuiting in the outlet liquor. However, it is a more efficient
skimmer than
No. 7 Soap Skimmer in Savannah was when it was baffled in the same way.
This is
because No. 1 Skimmer in Montgomery is more shallow and has a longer
residence
time. The most efficient baffling for a circular skimmer is that
observed on
No. 2 and No. 3 Soap Skimmers in Montgomery, Alabama.
Liquor
Entry Point: Short
circuiting of the soap particles to the outlet liquor from the skimmer
may also
be reduced by carefully positioning the inlet liquor level. A study was
performed on No. 7 Soap Skimmer in Savannah, in which liquor entry
points were
located at four foot intervals down the side of the skim tank.
Initially the
liquor was introduced at the top most entry point and the skimmer
outlet tall
oil residual was noted. When the liquor entry point was lowered four
feet, a
significant increase in the outlet tall oil residual was noted as in
Table 3.
This finding
is consistent with the skimmer design parameters as proposed by
Dusenbury in
that it minimizes the distance which a soap particle must travel to
reach the
surface of the skim tank. A similar effect may be created if the
existing
liquor entry point is near the bottom of the skimmer by providing the
liquor
entering the skimmer with an updraft.
Influence
of Soap-Liquor Interface Position: It has been
proposed that skimmers ought to operate with a
thick soap pad, to insulate the skimmer, minimize the liquor carryover
with
the soap, and to densify the soap collected. On rectangular skimmers,
this
practice has led to an increased tall oil residual in the skimmer
output
liquor. In the Savannah Mill, rectangular skimmers are operated so as
to
maintain a small liquor interface at the discharge end of the soap
skimmer.
This minimizes the losses of the soap particles from the bottom of the
soap bed
due to suction effects at the skimmer discharge pump. These results are
summarized
in Table 2. The thermal loss in the skimmer resulting from operating
with a
small liquor interface is very small and reduces the total evaporator
capacity
less than 1%.
A similar
dependence of the outlet liquor tall oil residual on the soap-liquor
interface
position has been noted on No. 7 Soap Skimmer as is illustrated in
Figure 4. It
is generally not necessary for an operator to adjust the skimmer level
to
control the soap liquor interface more often than oce/shift on any of
the
skimmers.
Miscellaneous
Applications of Tall Oil
Tall
Oil Fatty Acids for Chemical
Intermediates
The nature
and ratio of the fatty acids comprising tall oil fatty acids, as well
as the
non-fatty content, governs the behavior and properties of derived
products.
Commercial advantages other than low cost for tall oil fatty acids and
their
derivatives must arise from the properties due to the special nature
and
combinations of the constituents. The use of tall oil fatty acids,
containing
at least 90 percent fatty acids, is preferred for preparation of
intermediates.
( rude tall oil or tall oil products can be used if it is known that
the rosin
or other nonfatty acid components do not unfavorably affect the use of
the
intermediates. For example, crude tall oil (25 percent or more rosin
acid
content) has been satisfactorily used in the preparation of rigid
urethane foam
to effect lower costs.
Good quality
tall oil fatty acid is unique in containing a high content of oleic and
linoleic acids with little or no linolenic or other highly unsaturated
acids.
It also has a low content (about 3 percent) of
saturated acids, chiefly
palmitic acid. Oleic acid is present to the extent of about 48 to 52
percent
and linoleic acid to the extent of about 43 to 48 percent (37 to 42
percent
nonconjugated; 6 percent conjugated). Rosin acid content may be less
than 1
percent and neutrals content is usually less than 2 percent.
Tall oil fatty
acids, like other unsaturated fatty acids, can
be reacted at the carboxyl group and at the unsaturated linkages, or at
both
points. As noted earlier for tall oil fatty acids, the varieties and
uses of
intermediates obtainable from tall oil fatty acids are so numerous that
a
comprehensive coverage is impractical.
Reactions at the
carboxyl group to form soaps and esters have
been considered elsewhere, as have reactions at the unsaturated
linkages to
form sulfation or sulfonation compounds. Additional reactions that can
be
carried out at the carboxyl group include formation of amides,
nitrites,
amines, and-quaternary ammonium compounds. Alcohols are also
obtainable. All of
these products can be hydrogenated at the double bonds to obtain the
saturated
forms. A wide range of derivatives is thus available as with fatty
acids from
other sources.
Applications
include use of the cationic amine and quaternary
ammonium compounds in the flotation and textile fields. Condensates of
tall oil
fatty acids with alkylol amines find use in detergents and emulsifiers.
Fatty
amines and their salts derived from tall oil have been proposed for
many uses
such as for flotation agents, corrosion inhibitors, antistatic agents,
wetting
and dispersing agents, and lubricants. Stabilized tall oil nitriles and
amines,
substantially free of rosin acids, are the subject of patents with
suggested
uses in disinfectants, detergents, etc.
Polyethoxylated
fatty acids have been proposed as dispersing
agents, pesticide wetting agents, etc. Polyethoxylated acids derived
from tall
oil fatty acids having 4 percent and 70 percent rosin acid contents are
included in commercial offerings.
In all cases,
practical use must be dependent on special properties offering
advantages over
corresponding derivatives of fatty acids from other sources.
Hydrogenation of
tall oil fatty acids supplies the C18 saturated,
stearic acid, with very little C16 palmitic
or other acids being present.
Polymerized
Fatty Acids
The unsaturated
nature of tall oil fatty acids permits their
use as a suitable source for the commercial polymerized fatty acids.
These are
obtained by polymerization of unsaturated fatty acids under conditions
minimizing degradation. The polymerized fatty acids consist of dimer (C36) and trimer
(C54) acids. They
are sometimes referred to as dilinoleic and
polymeric fatty acids. Such acids have found wide use in industry and a
large
number of patents for their use have been issued. In the polymerization
of the
unsaturated fatty acids, some monobasic acids are formed, which are
characterized by some double-bond shifting, skeletal rearrangement and
cis-trans isomerization. An excellent review article on dimerization is
available.
The polymeric
acids undergo most of the reactions of
polybasic acids in general. Among the more important commercial
derivatives are
the polyamide products obtained by reacting the polymeric acids with
polyamines. These polyamides are of solid and liquid types. Solid
polyamide
resins based on polymerized fatty acids have a variety of end uses
including
vehicles for printing inks, in formulation of hot-melt adhesives, as
organic
solders for side-seam sealants of cans, in preparation of thixotropic
paint
vehicles, as antisagging agents for paints, in resinous systems for
paper
coating, and as wax modifiers. Liquid polyamides are used primarily as
epoxy
resin curing agents and the epoxy resin-polyamide resin systems are
used in
surface coatings, structural adhesives and sealants, tough castings,
structural
laminates, and auto-body solders.
Azelaic
and Pelargonic Acids
The presence
of unsaturation in tall oil fatty acids permits application of the
oxidative
cleavage reaction to form shorter chain dibasic and monobasic acids.
Although
cleavage can be effected by chromic acid, nitric acid, etc., ozone is
now used
in commercial practice to obtain the dibasic azelaic acid and the
monobasic
pelargonic acid. Here again, industrial utility depends on the nature
of the
fatty acids being such as to confer useful properties on the products.
A
favorable factor for use of tall oil fatty acids for preparing dibasic
and
monobasic acids is the low content of saturated fatty acids compared to
the
relatively large amount of palmitic and stearic acids in most of the
commercially available grades of oleic acid. Relatively low cost is
another
advantage. The high linoleic acid content of tall oil fatty acids,
however,
results in high chemical cost and more fragmentation products than is
the case
when using oleic acid as the feedstock.
The resulting
odd carbon C9 dibasic
azelaic acid
and C9 monobasic
pelargonic
acid have many uses and numerous patents have been issued. Azelaic acid
is
especially valuable as a building block for polymers, plasticizers, and
lubricant compounds. Pelargonic acid finds most of its outlets in the
manufacture of lubricants, plasticizers, flotation agents, perfume
bases, fungistats,
and wetting compounds.
Tall
Oil in Coprecipitated
Barium Salts
Calcium or
barium tallates can be employed in the preparation of toluidine reds.
The
pigment is treated with a tall oil fatty acid having an acid number
196, 97.6
percent fatty acid, and 0.9 to 1.3 percent free rosin acids. The tall
oil fatty
acid is in the form of calcium or barium salts, up to 25 percent by
weight of
the pigment. A solution of the calcium or barium chloride is added to
the
sodium tallate, and a precipitate of the tallate is obtained. The
surface of
the pigment particles is then changed.
Lithol reds
and maroons constitute one of the most widely used groups of organic
colors.
This is due to their relatively low cost, wide range of color, and good
color
strength. Lithols are prepared by diazotizing Tobias acid and coupling
it with b-napthol in the
presence of sodium
hydroxide. This gives the relatively insoluble sodium lithol. The
barium,
calcium, or strontium lithols are obtained by reacting the sodium
lithol with
suitable salts of the other metals. The differences in color of the
lithols
depends chiefly on the metal used for precipitation. The sodium lithols
are
light yellow reds, barium lithols are medium reds, and the calcium
lithols are
deep reds to maroons. The strontium lithols range in color between the
barium
and calcium lithols.
Lithols are
available in both nonrosinated and rosinated forms. Rosination, a
special case
of surface treatment for the particles, is accomplished during
manufacture of
the pigment by insolubilizing alkali rosinate simultaneously with the
dyestuff.
The rosinated types may contain 15 to 30 percent of metallic rosinate.
Rosinated lithols are more brilliant in color, more transparent,
produce
greater gloss in printing inks, and are more readily dispersed in
vehicles than
are the nonrosinated types. Also, they have higher oil absorption and
tend to
produce a thixotropic consistency.
Tall
Oil in Defoamers
Foams, in one
form or another, are frequently encountered in chemical technology.
Sometimes
their presence heralds difficulties in process and equipment operation.
Reaction vessels, gas-liquid contactors, and stirred tanks in general
are
frequently troubled with foam buildup.
One of the
chemical processes most troubled with foaming is the fermentation
industry.
Here, large batches of liquid medium containing surface-active
substances, and
usually finely divided solids as well, are sparged with great volumes
of air.
Foaming is rapid and generally persistent, since conditions are very
favorable
for foam production.
A foam can be
destroyed if its films are subjected to sufficiently great stresses. If
the
foam’s “elasticity” is unable to counteract these stresses, the
resultant
strains cause rupture and breakdown of the foam structure. In essence,
methods
of foam destruction are based on the reversal of those factors that
contribute
to foam stability. By reversing or inhibiting the natural stabilizing
influences in the foam, it can be caused to collapse.
Antifoam
agents (defoamers) constitute one of the most effective and widely used
means
of foam control. They offer the advantage of rapid and reasonable
lasting
action with high specific activity requiring only small amounts of
antifoam
agents.
Antifoam
agents are themselves surface-active. Their specific feature is a very
rapid
decrease in surface tension with concentration. When dropped or sprayed
on to
an existing stable foam, they cause extreme and rapid local variations
in
surface tension. Since their surface activity is greater than that of
other
substances, they concentrate at bubble film interfaces and force the
liquid
away. The film, so thinned, is weakened and breaks.
Foam
formation is not just a matter of low surface tension alone. Antifoam
agents
produce low surface tensions but do not readily produce stable foams
themselves. Chemical foam control is an essentially competitive
process. The
defoamers monopolize the surface layer but do not support foam
formation. In
doing so they keep away other surface-active agents that can produce
persistent
foams.
Antifoaming
agents comprising a condensate of 6 moles of ethylene oxide and 1 mole
of tall
oil fatty acids can be employed in the aqueous nutrient fermentation
media used
in the manufacture of yeast. No toxic effects can be observed, either
microscopically or by filtration performance, and no off-odor can be
detected
after washing.
Condensates
of ethylene oxide with products containing abietic acid, e.g., rosin,
rosin
oil, or tall oil, have been cited in the patent literature as suitable
foam-inhibiting agents for nutrient media for yeast and molds,
penicillin, and
streptomycin. Ratios of 0.76 to 6.0 moles of ethylene oxide per mole of
abietic
acid give most satisfactory results.
In the
manufacture of phosphoric acid by the wet-process, foaming problems
invariably
occur, especially when the process is operated at high production rate.
In this
case, a 4 percent rosin tall oil acid can be used very effectively as a
defoamer.
To inhibit
the production of foam in the reaction between soda ash and mineral
acids,
especially in the preparation of NaH2PO4
from
Na2CO3 and
85 percent H3PO4, refined or
purified tall oil
(50-600 ppm by wt.) is added to the Na2CO3 (dry
or in a slurry). Tall oil is introduced
in a continuous process into the mixing vessel in an amount to provide
10-800
ppm of the soda ash. The tall oil reduces the foam by more than half.
The
papermaking industry is particularly concerned with combating foam
troubles.
Foams or bubbles of gas in paper stock cause many difficulties in the
papermaking system and in the final product. In addition to detrimental
effects
on stock pumping, drainage on the wire, sheet formation, and internal
sizing,
foam may collect resin particles occurring naturally in the pulp and
cause
pitch trouble. Foam troubles may also occur in pigment coating of
paper,
surface-sizing solutions, and black-liquor recovery.
Antifoams may
be added directly to the stock close to the point where foam is most
troublesome, or they may be sprayed in the form of a fine, dilute
emulsion onto
the stock on the paper-machine wire. Fatty acids and fatty acid esters,
amides
of fatty acids, and metallic soaps of fatty acids are some of the foam
inhibitors used by the paper industry. Usually between 0.01 and 1.0
percent
defoaming agent is required on the basis of the air-dry pulp.
Products
useful as defoamers for paper-mill Whitewater can be prepared as
follows: 5.1
parts acid refined tall oil, 11.9 parts polyethylene glycol (600)
monooleate,
and 63 parts paraffin oil are mixed at room temperature. To this are
added 20
parts diethylene glycol monooleate and the mixture is heated to 75°C
(177°F)
until clear.
Another
formulation can be made by mixing 10.2 parts acid refined tall oil, 6.8
parts
polyethylene glycol (400) monoester of coconut fatty acids, and 63
parts
paraffin oil. To this is added 20 parts of diethylene glycol monooleate
and the
mixture heated to 75°C (177°F) until clear.
Effective
foam-suppressing compositions, which are nontoxic and applicable in a
wide
range of foaming media, can be prepared from tall oil pitch. The
pitch
is subjected to countercurrent fractionation with propane at 54°-104°C
(130°-220°F) and 550 to 575 psi. The pitch is separated into a
sterol-rich
raffinate and a tarry residue. The raffinate phase is saponified with
alcoholic
alkali to liberate combined sterols, which are then crystallized and
filtered
from the mixture. The filtrate is acidified to release the acids
present, and
the alcohol is recovered by distillation. The alcohol-free filtrate is
washed
with water to removal residual acid. The resultant liquid product,
which is the
active defoamer, contains 20 to 45 percent fatty acids, 20 to 50
percent rosin
acids, and 15 to 30 percent neutral material.
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