Note: Descriptions are shown in the official language in which they were submitted.
l~ki~
-- 2 --
It is described (see, for example, B.Bach and
G.Fiehn, Zellstoff und Papier 21, 3 (1972); H.H. Holton,
Pulp and Paper Canada 78, 19 (1977); u.s. Patent Specifica-
tion 4, 012,280; U.S. Patent Specification 4, 036, 680; U.S.
Patent Specification 4,036,681, Canadian Patent Specifica-
tion 986,662, Japanese Laid-Open Specification 112,903/75,
Japanese Laid-Open Specification 43,403/?6, Japanese Laid-
Open Specification 109,303/76 and German Democratic Republic
Patent Specification 98,549) tha~ anthraquinone, certain
anthraquinone derivatives and certain diketohydroanthracenes
exert a favourable effect in certain processes for the
production and bleaching of pulp from lignocellulose
materials, such as wood, straw and bagasse, when from 0.001
to lQ% by weight of them, relative to the lignocellulose
material, is employed. In addition to anthraquinone,
anthrahydroquinone and Diels-Alder adducts of butadiene and
its derivatives with p-benzoquinone or 1,4-naphthoquinone, the
mono- and poly-alkyl, -alkoxy, -amino, -hydroxyl and/or
-sulpho derivatives of these compounds are recommended for
this. In the following text, these substances are
collectively designated additives.
In general, the additives are accessible in the form
of powders. However, the incorporation of pulverulent
additives of this type into processes for the production of
pulps from lignocellulose materials and for the bleaching
thereof presents problems. If the pulverulent additives
are added to the lignocellulose material to be employed, it
must be expecteds in this case, that the finer constituents
of the additives pass into the environment in the form of a
dust and are thus partly withdrawn from the intended use,
are troublesome to people working near the place of addition
and can give rise to the danger of dust explosions. In
addition, uniform distribution is difficult with the rela-
tively small amount of additives required. However,
uniform distribution of the additives is desirable in order
to achieve uniform quality of the pulp.
Uniform distribution of the additives is also made
difficult by the fact that the additives are generally only
Le A 18 801
' ~
113~
very slightly soluble in water and in the aqueous elec-trolyte
solutions used in pulp production Ifor example, only 6.10 4 g
of 9,10-anthraquinone dissolves in 1 litre of water at 50C).
Furthermore, the additives are so poorly wetted by
water and aqueous electrolyte solutions, such as are used in pulp
production, that the finer constituents of the pulverulent
additives cannot be stirred in, or can only be stirred in to a
poor extent, but float non-wetted on the surface, air sometimes
being included. Moreover, the additives have a relatively high
specific density (for example anthraquinone has a specific density
of 1.438 g/cm at 20C), so that the coarser constituents of the
pulverulent additives, which can be stirred into water or an
electrolyte solution, rapidly settle again and, after standing for
a short time, form on the floor of the vessel a compact layer
which can be stirred up again only with difficulty. The addition
of the additives directly to the cooking liquor, to the mixture
of lignocellulose material and cooking liquor or in the form of a
slurry in water or dilute electrolyte solutions is thus also no
way of achieving with certainty a uniform distribution of the
additives.
A dispersion has now been found for use in pulp pro-
duction, which is characterised in that it contains an art recog-
nized pulp additive selected from organic, cyclic compounds con-
taining keto and/or hydroxyl groups, and a liquid dispersing
agent having a specific density which is the same as or similar
to said organic, cyclic compound.
3 --
1~3~
Elere and in the fol]owing text, the expression pulp
production is understood as all processes and process staqes in
which the lignin in lignin-containing and cellulose-containing
materials is acted upon in a chemical manner. Examples of these
processes are alkaline, neutral and acid pulping processes with
lignocellulose materials, such as wood, straw, bagasse and
grasses, and bleaching processes with partially or sub-
stantially pulped
- 3a -
i
-- 4 --
li~nocellulose materials.
Examples of possible organic, cyclic compounds con~
taining keto groups and/or hydroxyl groups are preferably
carbocyclic aromatic compounds which are monocyclic,
dicyclic and/or polycyclic, in particular monocyclic, di-
cyclic and/or tricyclic, and particularly preferably tri-
cyclic, especially condensed ring tricyclic compounds which
contain two keto groups and/or two hydroxyl groups and are
preferably hydrocarbons except for the keto or hydroxy groups
but can be further substituted. Compounds which can be used
here are, preferably, ?-benzoquinone, l,4-naphthoquinone, 9,lO-
anthraquinone and/or Diels-Alder adducts of l,3-dienes, for
example of unsubstituted or substituted butadiene, with p-
benzoquinone and/or l,4-naphthoquinone, and/cr mono- and poly-
alkyl, -hydrcxyl, -amino, -alkoxy, -alkylamino and/or sulpho
derivatives thereof. The alkyl, alkoxy and alkylamino moieties
can each contain, for example~1 to 12 carbon atoms, preferably
l to 4 carbon atoms. For example, the dispersions according
to the invention can contain 9,lO-anthraquinone, 2-methyl-
anthraquinone, 2-ethylanthraquinone, 2,3-dimethyl-
9,lO-anthraquinone, 2,6-dimethylanthraquinone, 2,7-
dimethylanthraquinone, 2-aminoanthraquinone, l-methoxy-
anthraquinone, l,4 9 4a,9a-tetrahydro-9,lO-diketoanthracene,
2-ethyl-1,4,4a~9a-Tetrahydro-9,lO-diketoanthracene, 2,3-
dimethyl-l,4,4a,9a-tetrahydro-9,lO-diketoanthracene,
l,4,4a,5,8,8a,9a 9 lOa-octahydro-9,lO-diketoanthracene, l,3-
dimethyl-l,4,4a,9a-tetrahydro-9,lO-diketoanthracene and
2,3,6,7-tetramethyl-1,4,4a,5,8,8a,9a,10a-octahydro-9,lO-di-
ketoanthracene. Specifically included as compounds which can
be used are the above named compounds in reduced form containing
hydroxy instead of keto groups. Such as for example hy~roquinone
and anthrahydroquinone. The dispersions according to the inven-
tion can contain two or more of these substances, in par-
ticular two or more of these substances which have
specific densities which are close to one another. It
is also possible to employ compounds which carry two or
more of the substituents ~entioned, for example hydroxyl
groups and amino groups. However, the dispersion accord-
Le A 18 801
~ ~ 3
-- 5 --
ing to the invention preferably contains only one of thesesubstances~ very particularly preferably 9,10-anthraquin-
one. In the following text, the organic, cyclic com-
pounds containing keto groups and/or hydroxyl groups are
designated as "dispersed substances".
The dispersed substances, in particular 9,10-
anthraquinone, can be present in the most diverse particle
sizes. For example, the dispersed substances, in
particular monocyclic, dicyclic and/or polycyclic com-
pounds containlng keto groups and/or Hydroxyl groups,especially 9,lO~anthraquinone, can consist to the extent o~
at least 80% by weight of particles with particle sizes in
the range from 1 ~m to 5 mm. The dispersed substances,
in particular anthraquinone, can also have particle sizes
in the range from about 50 to 500 ~m, with the highest fre
quency of particles in the range from about 200 to 300 ~m.
The particle size distribution has no particular influence.
me particle size distribution can lie relatively closely
around a mean value, but it can also extend over the entire
aboYementioned ranges and beyond. With regard to the
use of 9,10-anthraquinone, this has the advantage that
anthraquinone can be introduced into the dispersion accord-
ing to the invention in the form in which it is generally
obtained in the industrial preparation.
Liquids which have a specific density which is the
same as or similar to the dispersed substance or the dis-
persed substances are suitable dispersing agents for the
dispersion according to the invention. Liquids are
understood here as pure liquid substances, solutions and
dispersions. m e dispersing agent can be, for example,
an aqueous solution of electrolytes which has a specific
density in the range from 1.2 to 1.6 g/cm3. In the case
where 9,10-anthraquinone is the dispersed substance, the
specific density of the dispersing agent is preferably 1.35
to 1.5 g/cm3, particularly preferably 1.4 to 1.45 g/cm~.
Le A 18 8cl
113~i~0
-- 6 --
The aqueous solution of electrolytes can be, for
example, a solution of oxides, hydroxides and/or salts of
the metals of the first and/or second main group of the
periodic system, andlor a solution of nitrogen bases and/or
of salts of nitrogen bases or a solution of acids. The
first and second main groups of the periodic table are those
given as group Ia and group IIa in, for example, the end
sheets of Cotton & Wil~inson "Advanced Inorganic Chemistry",
second edition. Which of these electrolytes dissolve
in water in amounts such that solutions of the desired
specific density are formed can be easily determined
by simple preliminary e.Yperiments or by reference to corres-
ponding tables.
m e aqueous solution is preferably a solution of
oxides, hydroxides, sulphides, sulphites, bisulphites,
sulphates, thiosulphates and/or carbonates of sodium,
potassium, calcium and/or magnesium. Examples of nitrogen
bases are alkylamines, hydroxy-alkylamines or alkylene dia-
mines having preferably up to 12 carbon atoms such as ethylene
diamine 9 propylamine and/or ethanolamine, examples of salts
of nitrogen bases are ammonium salts such as acid-addition
salts or quaternary salts and examples for acids are sulfuric
acid, phosphoric acid and nitric acid. The aqueous
solution is particularly preferably a solution of sodium
hydroxide, sodi~ sulphide, sodium sulphite, sodium bisul-
phite, sodium sulphate, sodium thiosulphate~ sodium car-
bonate, potassium sulphide9 magnesium bisulphite, calcium
bisulphite and/or ammonium sulphite or sulphonic acid~ A
solution of sodium hydroxide, sodium bisulphite and/or sodium
thiosulphate is especially preferred as the aqueous solution.
It is not necessary to restrict the electrolyte to a single
one of the electrolytes indicated. Rather, solutions or
suspensions o~ mixtures of the electrolytes listed can also
be used. It is advantageous to use those aqueous solu-
tions of electrolytes such as can be removed at variouspoints in the installations for pulp production. Elec-
r ~--
Le A 18 801
. .
-- 7 --
trolyte solutions which are removed from various points inthe installation for pulp production can appropriately be
used as dispersing agents, after concentration, for
example by evaporating off water, or after adding further
amounts of electrolytes. For example, the so-Galled
white liquors, cooking liquors, black liquors, thick
liquors and/or green liquors can be used as dispersing
agents, if appropriate after accordingly adjusting the den-
sity by evaporating off water or adding further amounts of
electrolyte.
Here and in the following text, by these terms
there are understood the following solutions:
"Cooking liquor"is defined as solutions which are
combined with the lignocellulose material before the pulp-
ing. meir composition, with respect to the natureand concentration of the constituents, can vary within wide
limits, depending on the nature of the lignocellulose
material to be pulped and on the pulping process applied.
For example, the cooking liquor can contain 8 to 20~ by
weight of alkali metal base, expressed as per cent of
effective alkali, relative to the weight of the lignoc~llu-
lose material, and in addition can usually also contain
alkali metal carbonate. However, cooking liquor can
also contain, for example, 8 to 15% by weight of alkali
metal base, expressed as per cent of effective alkali
(TAPPI T-120 S 61) and 5 to 40% by weight of alkali metal
sulphide, expressed as per cent sulphidity (TAPPI T-1203
OS-61), relative to lignocellulose material. mis cook-
ing liquor usually also containsalkali metal sulphate and
alkali metal carbonate, and optionally also sulphur in an
amount of l to 5% by weight.
"Black liquors" are defined as the spent cooking
liquors separated off from the pulp after the pulping of
the lignocellulose material has been carried out. m ese
contain, as organic constituents, the concomitant substances
of cellulose, which have been rendered soluble, for example
Le A 18 ~01
__
-- 8 --
lignin-sulphonates and/or alkali-lignins, and appropriately
also hemicelluloses and low-molecular conversion products
of the constituents of the lignocellulose material, and as
inorganic constituents, for example, mainly alkali metal
sulphate and alkali metal carbonate, as well as alkali metal
base bonded to acid organic constituents, and in addition
usually also free alkali metal base, alkali metal sulphide,
alkali metal sulphite and alkali metal thiosulphate.
m e specific densities of the black liquors can be, for
example, 1.05 to 1.40 g/cm3, depending on the concentration
of the dissolved substances. The solids content can vary,
for example, within the limits of lO to 70% by weight.
"Thick liquor" is defined as those black liquors
which, because of a high solids content of, for example,
more than 50% by weight. are highly viscous at room tem-
perature. Depending on the pulping process, thick
liquors can be obtained immediately by separating off from
pulps, or by evaporating black liquors with a low solids
content.
"Green liquors" are defined as solutions which con-
tain, for example, 5 to 20% by weight of alkali metal car-
bonate and, for example, l to 5% by weight of alkali metal
sulphide and which are prepared from water and that salt
melt which is obtained during combustion of the organic
constituents of the thick liquors. Green liquors
usually also contain sodium sulphate, sodium sulphite,
sodium thiosulphate and sulphur. Green liquor has a
specific density, for example, in the range from l.l to
l.30 g/cm3.
"White liquors"are defined as the liquors obtained
from green liquors by treatment with quicklime. White
liquors contain, for example9 80 to 200 g of alkali metal
base, lO to 80 g of ~lkali metal sulphide and 20 to 50 g of
alkali metal carbonate per litre of solution. They
Le A 18 801
~3~0~
g ~
usually al50 contain alkali metal sulphite, alkali metal
sulphate and alkali metal thiosulphate, and optionally also
sulphur. Their solids content is, for example, about 10
to 35% by weight. The specific density of the white
liquors is, for example, between l.l and l.3 g/cm3.
The concentration of dispersed substances in the
dispersion according to the invention can be adjusted as
desired within wide limits. Practical limits are given
by the need to be able to pump the material in the case of
a high content of dispersed substances, and, in the case of
a low content of dispersed substances, by the high amount
of electrolyte employed in relation to the dispersed sub-
stance. me dispersion according to the invention can
have, for example, a content of dispersed substances of 5
to 70% by weight, preferably of 30 to 60% by weight.
A particular embodiment of the dispersion according
to the invention is characterised in that it additionally
contains wetting agents. Possible wetting agents are
cationic, anionic or non-ionic wetting agents, preferably
those which are obtained as by-products in the processes
for pulp production. Examples of these are black
liquor, thick liquor and/or the lignin-sulphonates or
alkali-lignins obtainable therefrom. Wetting agents can
be added in amounts of, for example, O.Ol to 20 per cent,
preferably of 0.05 to lO per cent, relative to the weight
of the dispersion. m e addition of wetting agents can
be ef~ected, for example, by adding the pulverulent wetting
agent to the pulve~ulent substance to be dispersed, before
the preparation of the dispersion. The wetting agent
can also be added in the liquid or solid form to the liquid
dispersing agent.
A further particular embodiment of the dispersions
according to the invention is characterised in that theyaddi-
tionally contain substances which increase the viscosity.
Examples of possible substances which increase the viscosity
Le A 18 801
3~
- 10 -
are water-soluble polymeric compounds, such as polyvinyl
alcohol and/or methylcellulose. Thick liquor can also be
used, that is to say black liquor concentrated, for example,
to a solids content of 50 to 70%. Pure thick liquor, for
example with a solids content of 64%, which is a highly vis-
cous mass at 20C, forms, for example at 80C, a stable dis-
persion with anthraquinone, in spite of a specific density
of only 1.25 g/cm3. The favourable viscosity-increasing
ef~ect of the thick liquor is also exerted in the case of
mixtures of 60 parts of thick liquor and 40 parts of water
or in the case of mixtures of 50 parts of thick liquor and
50 parts of white liquor. Inorganic substances, such as
polysilicates, for example pyrogenically obtained silicic
acid with a specific surface area of about 380 m2/g, can
also be employed as substances which increase the viscosity.
It is usually not particularly advantageous to use inorganic
substances which increase the viscosity, since these are not
removed by combustion and can become enriched in the pro-
cess for pulp production. Polyvinyl alcohol and methyl-
cellulose are therefore particularly preferably used assubstances which increase the viscosity. The use of
thick liquor or mixtures containing thick liquor with water
or electrolyte solutions is also favourable. The dis-
persing agent can contain polyvinyl alcohol and/or methyl-
cellulose, for example, in amounts of 5 to 20% by weight,and thick liquor in amounts of, for example, 50 to 100% by
weight.
The dispersion according to the invention which
contains substances which increase the viscosity has the
advantage that this dispersion is also stable if the speci-
fic density of the dispersing agent deviates markedly from
- the specific density of the dispersed substance. An
electrolyte solution with a relatively low concentration can
therefore be used as the dispersing agent if substances
which increase the viscosity are present. For example,
dispersions containing 9,10-anthraquinone (specific density
Le A 18 801
0~
- 11 -
of anthraquinone at 20C: 1.438 g/cm3) are obtained,
in the presence of substances which increase the viscosity,
if the dispersing agent has a specific density of about
1.25 g/cm3. Some of the electrolytes for the prepara-
tion of the dispersing agent can therefore be saved.
A similar effect to the addition of substances which
increase the viscosity is obtained in the dispersions
according to the invention if a carrier dispersion is used
as the dispersing agent. By the term carrier dispersion
there is understood here, and in the follo~ing text, a dis-
persing agent which is already present as a dispersion
before the addition of the organicy cyclic compounds con-
taining keto groups and/or hydro~yl groups. Carrier dis-
persions of this type can be obtained, for example, by
bringing together thick liquor or black liquor and concen-
trated aqueous electrolyte solutions of the type described
above or solid electrolytes of the type described above, in
particular sodium hydroxide solution or sodium hydroxide.
The use of carrier dispersions has the particular advantage
that using waste substances of the process itself and a
reduced amount of electrolytes, a dispersion is obtained
which can be handled at room temperature without problems.
m e temperature is not a decisive parameter in the
preparation, storage and application of the dispersion
according to the invention and can be chosen as desired
within wide limits. me ambient temperature is to be
regarded as a practical lower value and the temperature at
which substantial amounts of water evaporate offunder normal
pressure, the specific density of the dispersing agent being
shifted, is to be regarded as a practical upper value.
If thick liquor is employed as a wetting
agent, as a viscosity-increasing substance and/or as a com-
ponent for the formation of a carrier dispersion, a working
temperature in the ra~ge from 50 to 90C is advisable, since
thick liquor solidifies on contact with cold water or cold
electrolyte solution and is only gradually dissolved or dis-
persed.
- Le A 18 801
___
~3~Q~
- 12 -
The dispersion according to the invention can be
prepared in various manners. For example, the substance
to be dispersed can be stirred into -the prepared dispersing
agent. If the dispersing agent is composed of two or
more constituents, the sequence of the addition can be
chosen freely. me substance to be dispersed can be
stirred into the previously prepared dispersing agent,
which optionally contains a wetting agent and/or a substance
which lncreases the viscosity and/or a carrier suspension.
The substance to be dispersed can also be stirred into the
aqueous electrolyte solution, having the same density or a
similar density, and a wetting agent and/or a viscosity-
increasing substance can be subsequently added. It is
also possible to follow a procedure in which the substance
to be dispersed is first mixed with a wetting agent in the
solid or liquid form, and this mixture is then introduced
into an electrolyte solution. Furthermore, the substance
to be dispersed can be mixed with the solid electrolyte,
for example with solid sodium hydroxide, optionally
together with a wetting agent, and water can be added to
this mixture, or this mixture can be added to water.
m e substance to be dispersed can also be dispersed in thick
liquor and an electrolyte solution canthenbe added, acarrier
dispersion being formed.
~ particularly preferred dispersion within the scope
of the dispersions according to the invention is charac-
terised in that it contains 30 to 60% by weight of 9,lO-
anthraquinone, which has, to the extent of at least 80%, a
particle size in the range from 50 to 500 ~m, and contains
40 to 70% by weight of an aqueous solution, which contains
sodium hydroxide, sodium sulphide, sodium sulphite, sodium
thiosulphateS sodium carbonate, magnesium bisulphite, calsium bi-
sulphite and/or ammonium ~ulphite or sulfuric acid and has a den-
sity in the range from 1.35 to 1.5 g/cm3, and contains 0.05 to
~13g-~0&~
- 13 _
10% by weight of a wetting agent, and the aqueous solution
in the dispersion is optionally replaced, to the extent of
50 to 100% by weight? by thick liquor or by a carrier dis-
persion. A very particularly preferred dispersion within
the scope of the dispersion according to the invention has
the above characteristics, the aqueous solution containing
sodium hydroxide, sodium bisulphite and/or sodium thio-
sulphate.
m e dispersion according to the invention, in par-
ticular the dispersion containing anthraquinone, is used inprocesses for pulp production. In pulp production, the
dispersion according to the invention can be fed in before
the cooking, but advantageously already before the impreg-
nation, in which the lignocellulose material is impregnated
withanaqueous solution ofthepulpingchemicals at a tempera-
ture of80to100C. m e aqueous solution of the pulping
chemicals also serves as a conveying medium for charging the
impregnator and/or cooker with lignscellulose material.
me dispersion according to the invention, in particular a
dispersion containing anthraquinone, can be metered, by
pumping, into the refluxing solution or into the solution
charged with chips, or optionally also directly into the
impregnator or cooker. The anthraquinone generally
thereby dissolves and can thus penetrate in molecular form
into the chips during the impregnating process. This has
the result that pulps of uniform quality are obtained.
The amount and composition of the dispersion accord-
ing to the invention used in pulp production can be chosen
so that, for example, 0.01 to 1.0% by weight of the amount
of chemicals required for the pulping is added, in the form
of the dispersion according to the invention, to the pulping
solution. In a process for pulp production with, for
example, 99% recycling of the pulping chemicals, this
corresponds to 0.01 to 1.0 times the amount of pulping
chemicals which must be freshly added to compensate losses.
me dispersion according to the invention, in par-
ticular a dispersion containing anthraquinone~ has a number
of advantages. Thus, the preparation of these disper-
Le A 18 801
3~
- 14 -
sions is simple and can be carried out without special
equipment. me dispersion according to the invention can
be pumped, that is to say it can be metered, and conveyed
through pipelines, with the aid of a pump suitable for pump-
ing dispersions, for example a peristaltic pump, an eccen-
tric screw pump or a piston pump~ The dispersion accord-
ing to the invention is stable for a relatively long time.
It can be stored for at least several days, in general for
one or more weeks, during which the dispersed substances do
not settle or float to the surface, or settle or float to
the surface only to such a slight extent that they can be
brought into the dispersed state again by a simple means,
for example a slow-speed stirrer. This has the advantage
that a relatively large amount of the dispersion can be pre-
pared all at once, the metering ofwhichcanthenbeeffected,for example, by a simple measurement of volume or amount.
The preparation of the dispersion according to the
invention can be carried out at a different place to the
pulp production, for example at the anthraquinone ~anu-
facturer's premises. In this case, the finished disper-
sion can be made available to the pulp producer. However,
the preparation of the dispersion according to theinvention
canalso takeplace atthepulpproducer's premisessince, for
example, with the exception of the substance to be dispersed,
it is possible to use only those substances which can any-
way be used in pulp production and/or are obtained thereby.
In this case, only the pure active compound, for example
anthraquinone, needs to be transported.
The metering of the dispersion according to the
invention is particularly simple. At a given feed
capacity of a metering pump, the metering of the dispersed
substance into the installation for pulp production can be
changed by establishing higher contents of dispersed sub-
stance by adding pulverulent substance to be dispersed and
establishing lower contents of dispersed substance by
adding dispersing agent. Thus, the dispersion according
to the invention can be adapted to the operating conditions
for pulp production and can be changed, without altering
- Le A 18 801
1~L3t~;~0E~
-- 15
the capacity of the metering pump.
By employing the dispersion according to the inven-
tion in processes for pulp production, including the
bleaching of pulp, the favourable effects of the presence of
organic, cyclic substances containing keto groups and/or
hydroxyl groups can be utilised in an optimum manner, with-
out disadvantages thereby arising. The organic constitu-
ents of the dispersion according to the invention are also
burned during the combustion of the effluents from the pro-
cess. The inorganic constituents of the dispersionaccording to the invention, in particular the aqueous
electrolyte solutions, can be chosen so that no substances
which are foreign to the process enter into the particular
process for pulp production. Furthermore, the inorganic
constituents can be adapted to the various processes for
pulp production. No concentration of substances which
are foreign to the process can then occur, which is par-
ticularly important in the case of modern processes for
pulp production, in which the pulping chemicals are re-
cycled.
It is to be described as distinctly surprising thatthe dispersion according to the invention completely fulfils
the requirements for use in pulp production, including the
bleaching of pulp. Stable dispersions are, in fact,
usually only obtained if the dispersed particles have a
particle size in the order of magnitude of colloid par-
ticles. In coarser dispersions, the dispersed particles
usually settle sooner or later (see R8mpp, Chemielexikon
(R8mpp's Chemical Dictionary), 6th edition, page 6,286
(1966)). Colloid particles can only be obtained in
expensive grinding processes. Such grinding processes
are not required for the preparation of the dispersion
according to the invention.
Furthermore, it was surprising that the dispersion
according to the invention can be prepared with dispersing
agents which enable the dispersion to be adapted to the
particular process for pulp production, since the dispersing
agents can be chosen from a wide range. A dispersion
Le A 18 801
1~3~ 0
16
according to the invention can thus be made available for
virtually any customary process for pulp production in which
no substances which are foreign to the process may be
introduced.
Moreover, a process has been found for pulp produc-
tion from lignocellulose materials in the presence of
organic, cyclic compounds containing keto groups and/or
hydroxyl groups, which is characterised in that the organic,
cyclic compounds containing keto groups and/or hydroxyl
groups are employed in the form of one of the dispersions
described above. With the exception of the use of the
dispersion according to the invention, this process can be
carried out in a manner which is in itself known. For
example, this process can be carried out by digesting ligno-
cellulose materials in a sulphite solution, which can beacid, neutral or alkaline, and adding the dispersion
according to the invention to the digestion solution9 before
or after adding the lignocellulose material It is also
possible to employ the dispersion according to the inven-
tion in the known processes for pulp production, which arecalled the Kraft process, soda process and polysulphide pro-
cess. Furthermore, the dispersion according to the
invention can be employed in the known oxygen/alkali pro-
cess for pulp production and/or in the bleaching processes
known for pulp production.
The dispersion according to the invention can be
employed in the process according to the invention for pulp
production and the bleaching of pulp in an amountl for
example, such that 0.01 to 1.0~ by weight of the amount of
chemicals required in the particular process are added in
the form of a dispersion according to the invention.
Preferably, 9,10-anthraquinone is employed in the
process according to the invention in the form of one of the
dispersions according to the invention. In this case~ it
is particularly preferable to use the dispersion designated
as particularly preferred within the scope o~ the dis-
persions according to the invention.
- The process according to the invention has a number
Le A 18 801
1~3~0
17 -
of advantages. Thus, for example, it is possible to
meter and uni~ormly distribute the organic, cyclic com-
pounds containing keto groups and/or hydroxyl groups without
difficulties, and as a result thereof, pulps of uniform
quality are obtained. Furthermore, it is possible to
realise the advantageous effects, determined on a laboratory
scale under ideal conditions, of the addition of organic,
cyclic compounds, containing keto groups and/or hydroxyl
groups, in industrial installations for pulp production.
In the laboratory experiments, for exampl~, the
lignocellulose material was agitated in the pulping liquid
or bleaching liquid, which facilitated distribution of the
additives. In industrial installations for pulp produc-
tion, this is the case only to a minor extent, and the dis-
tribution of the additives is thus made moredifficultifthey
are not employed in the form of the dispersion according to
the invention.
Examples
Unless otherwise indicated, an anthraquinone such as
is obtained in an industrial manufacturing process was
e~ployed in the Examples. 80% by weight of this anthra-
quinone has a particle size in the range from 100 to 500 ~m.
Example 1
50 g of 9,lO~anthraquinone are introduced into 50 g of a
41% strength aqueous sodium hydroxide solution (specific den-
sity 1.44 g/cm3), whilst stirring. The anthraquinone is
wetted well, ancl a thickish, pumpable dispersion is
obtained, the solids constituent of which floats to the sur-
face in the course of a few days as the result of included
air bubbles. Homogeneous distribution is achieved by
slowly stirring the dispersion.
Example 2
20 g of 9,10-anthraquinone are introduced, whilst
stirring, into a mixture of 75 g of 41% strength aqueous sodium
hydroxide solution and 5 g of black liquor with a specific
density of 1.1 g/cm~ and a solids content of 16.4% by
weight. A uniform mobile dispersion results. If,
after the dispersion has stood without being agitated for
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about 24 hours, included air is allowed to escape by careful
stirring, the dispersion is stable over a period of weeks.
E~ample ~
5,500 g of 9,10-anthraquinone are stirred into a mixture
of 4,000 g of 41% strength aqueous sodium hydroxide solution
and 500 g of black liquor corresponding to the black liquor
used in Example 2.
The thick, smooth, slightly thixotropic dispersion
can be pumped excellent]y and, even over a period of weeks,
shows no tendency towards separation.
Example 4
5 g of 9,10-anthraquinone are gradually stirred with a
mixture of 90 g of 41% strength aqueous sodium hydroxide solution
and 5 g of black liquor corresponding to the black liquor
used in Example 2. The solids constituent of the very
mobile dispersion obtained neither floats to the surface nor
settles.
Example 5 (Comparison Example)
40 g of 9,10-anthraquinone are stirred into a mix-
ture of 55 g of water and 5 g of black liquor correspondingto the black liquor used in Example 2. m e anthraquinone
is completely wetted and forms a relatively mobile disper-
sion, which, however, already begins to separate after a
short time. After a few days, the solid has consolidated
to form a hard sediment) which can virtually no longer be
stirred up.
Example 6
40 g of 9,10-anthraquinone are stirred into a mix-
ture of 55 g of 37% strength aqueous sodium hydroxide solution
(specific density 1.40 g/cm3) and 5 g of black liquor
corresponding to the black liquor used in Example 2. The
anthraquinone can be readily wetted to give a viscous dis-
persion w~ich can be easily metered by means of pumps.
After some days, the anthraquinone has settled loosely on
the floor of the vesselO
Example 7
The dispersion prepared from 40 g of 9,10-anthra-
quinone, 55 g of 50% strength aqueous odium hydroxide solution
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(specific density 1.53 g/cm3) and 5 g of black liquor
corresponding to the black liquor used in Example 2 allows
the solid to float to the surface. After 24 hours, the
dispersion can still be re-prepared in a simple manner.
After 14 days, however, the solids layer has consolidated to
form a thick viscous skin, so that re-preparation of the
dispersion is made more difficult. The separation can
already be avoided by stirring slowly.
Example 8
40 g of 9,10-anthraquinone are stirred into a mix-
ture of 55 g of 41% strength aquesus sodium hydroxide solution and
2 g of thick liquor with a specific density of 1.30 g/cm3
and a solids content of 64% by weight, which was diluted
with 3 g of water before combining with the sodium hydroxide
solution. m e dispersion, which is stable over a period
of several weeks, exhibits no difference to a dispersion of
the same concentration, in the preparation of which, how-
ever, 5 g of black liquor corresponding to the black ]iquor
used in Example 2 were employed as the wetting agent.
a~ 2
100 parts of 9,10-anthraquinone are mixed in a mill,
with grinding, with 1 part of isolated dry lignin-sulphonate.
The particle size of the anthraquinone was about 40 to
100 ~m. 50.5 g of this mixture are stirred into 49.5 g
of 41% strength aqueous sodium hydroxide solution. A thick dis-
persion is obtained which is stable over a period of weeks
and can be easily conveyed and metered by means of pumps.
Example 10
18.5 g of sodium hydroxide are added to 50 g of
9,10-anthraquinone and the components are mixed, with grind-
ing. Thereafter, the particle size of the anthraquinone
was about 40 to 100 ~m. After adding 5 g of black liquor
corresponding to the black liquor used in Example 2, and
26.5 g of water, a uniform dispersion, the stability of
whiGh is unchanged over a period of weeks, results.
Example 11
20.3 g of sodium hydroxide are added to 50.5 g of
the mixture, described in Example 9, of 9,10-anthraquinone
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and lignin-sulphonate in the ratio 100:1, and the components
are mixed, with grinding. The dry powder (anthraquinone
content: 70.6%) is stirred with 29.2 g of water to give a
50% strength anthraquinone dispersion. The dispersion is
stable over a period of at least 4 weeks.
ExamPle 12
30 g of 9,10-anthraquinone are dispersed in a mixture of
65 g of a 47.5% strength aqueous sodium thiosulphate solu-
tion (specific density at 50C: 1044 g/cm3) and 5 g of
black liquor corresponding to the black liquor used in
Example 2. The mobile dispersion shows no tendency at
all towards separation of the solid phase from the liquid
phase.
Example 13
300 g f Na2S203 . 5 H20 are dissolved in 100 ml of
water at 50C to give a 47.5% strength aqueous sodium thiosulphate
solution, which has the same density at 50C as 9,10-
anthraquinone. 5 g of black liquor corresponding to the
black liquor used in Example 2, and then 50 g of 9,10-
anthraquinone are added to 45 g of this solution. The
dispersion, which is thickish and pumpable at room tempera-
ture, is mobile at 80C and remains stable as a dispersion
over a period of at least 3 weeks.
Example lL~
120 g of 9,10-anthraquinone are dispersed in a mix-
ture of 100.7 g of white liquor, 54.3 g of sodium hydroxide
and 15 g of black liquor. The white liquor contained
92.8 g of NaOH, 34.3 g of Na2S and 23.3 g of Na2C03 per
litre. This corresponds to an effective alkalinity of
113 g/l and a sulphidity of 27.5%. The white liquor had
a specific density of 1.14 g/cm3 at 20C. The black
liquor corresponded to the black liquor used in Example 2.
The specific density of the mixture of white liquor
and sodium hydroxide is 1.44 g/cm3 at 20C. Relatively
little sodium hydroxide is required for the stable mobile
dispersion, which becomes reddish-coloured in the course of
some hours. (25% more sodium hydroxide is required for
the dispersion described in Example 8).
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It is advisable to first add the black liquor and
only then the sodium hydroxide to the white liquor, since
white liquor and sodium hydroxide otherwise form, in the
ratio indicated, a coarsely crystalline precipitate.
Example 15 (Comparison Example)
40 g of 9,10-anthraquinone introduced into 48 g of
white liquor corresponding to the white liquor used in
Example 14, with the addition of 12 g of black liquor
corresponding to the black liquor used in Example 2, form a
dispersion in which the anthraquinone rapidly sinks to the
ground and forms a compact layer which can only be stirred
up with difficulty.
Example 16
40 g of 9,10-anthra~uinone form an almost black
dispersion in 54 g of thick liquor~ corresponding to the
thick liquor used in Example 8, which has been diluted with
6 g of water. This dispersion is very viscous at room
temperature, but can be pumped at 80C.
ExamPle 17
50 g of 9,10-anthraquinone are mixed with 50 g of
thick liquor, warmed to 80C, corresponding to the thick
liquor used in F~ample 8~ 5 g of water are added to this
mixture in order to improve the ease of pumping of the mix-
ture. At 80C, the dispersion is stable and can be
metered. It is highly viscous at room temperature.
Exam~le 18
40 g of 9,10-anthraquinone are mixed, at 80C, with
48 g of thick liquor with a specific density of 1.25 g/cm3
at 80C and a solids content o~ 64% by weight, and 12 g of
saturated sodium carbonate solution. m e specific den-
sity of the dispersing agent is 1.34 g/cm3 at 20C.
At 80C the dispersion has a slight tendency to
settle. This can be avoided by stirring the dispersion
slowly.
~3~oe~
40 g of 9,10-anthraquinone are stirred into a mix-
ture of 48 g of thick liquor corresponding to the thick
liquor used in Example 8 and 12 g of white liquor corres-
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ponding to the white liquor used in Example 14. At 80C,
the stable dispersion, which can be poorly stirred at room
temperature, tends to form a sediment in the course of two
weeks, which can be stirred up again. The settling can
be avoided by stirring slowly.
Example 20
A stable dispersion which can be easily handled is
obtained from 40 g of 9,10-anthraquinone and 60 g of a
carrier dispersion prepared from 12 g of black liquor
corresponding to the black liquor used in Example 2 and 48 g
of a 50% strength aqueous sodium hydroxide solution.
Example 21
50 g of 9,lO~anthraquinone are added to a carrier
dispersion which has been prepared from 32.5 g of black
liquor corresponding to the black liquor used in Example 2 and
17.5 g of the sodium hydroxide. The disper,sion has a specific
density of 1.39 g/cm3 at 20C. The resulting dispersion can be
pumped and does not settle.
ExamPle 22
40 g of 9,10-anthraqu~none are stirred into a mixture
of 55 g of 56 96 strength aqueous sulfuric acid (specific density
1.46 g/cm3) and 5 g of black liquor corresponding to the black
liquor used in Example 2. A~ter two months, from the remarcably
mobile dispersion the anthraquinone has settled loosely on the
ground of the ves~el.
Example 23
The mobile dispersion prepared from 40 g of 9,10-
anthraquinone and 60 g of 60 % strength aqueous phosphoric
acid (specific density 1.43 g/cm3) remains stable as a
dispersion over a period of at least two weeks.
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