Note: Descriptions are shown in the official language in which they were submitted.
- P 001 00177-Foreign Countries WA/AB/XP
Ion exchanller for winning metals of value
The present invention relates to the use of monodisperse, macroporous anion
exchangers of type I
or type II in hydrometallurgical processes for winning metals of value. Type I
denotes resins
whose adsorbing sites are quaternary ammonium groups which are substituted by
alkyl groups.
Type II denotes resins in which the quatemary ammonium groups have not only
alkyl group(s) but
at least one hydroxyalkyl group.
Due to increasing industrialization in many parts of the world and
globalization, the demand for
numerous metals of value such as cobalt, nickel, zinc, manganese, copper,
gold, silver and also
uranium has increased considerably in recent years. Mining companies and
producers of industrial
metals are attempting to satisfy this increasing demand by means of various
measures. These
include improving the production processes themselves.
The metals of value relevant for industrial use are present in ore-bearing
rocks which are mined.
The ore which is then present in relatively large lumps is milled to give
small particles. The
materials of value can be leached from these rock particles by a number of
methods. The
customary technique is hydrometallurgy, also referred to as the wet method. If
appropriate, the ore
is subjected to a pretreatment to produce soluble compounds (roasting,
pyrogenic treatment) and
these are converted by means of acids or alkalis into aqueous metal salt
solutions. The choice of
solvent is determined by the type of metal, the form in which it is present in
the ore, the type of
accompanying rock in the ore (gangue) and the price. The most widely employed
solvent is
sulphuric acid, and hydrochloric acid, nitric acid and hot concentrated sodium
chloride solutions
are also possible. In the case of ores having acid-soluble accompanying
materials, for example,
copper ammoniacal solutions can also be used, sometimes also under high
pressure and elevated
temperature (pressure leaching). Sodium hydroxide is used for the winning of
aluminium oxide; in
the case of noble metals, alkali metal cyanide solutions are used. As an
alternative, the winning of
the metals in hydrometallurgy can also be carried out by precipitation or
displacement by means of
a less noble metal (cementation), by means of reduction by hydrogen or carbon
monoxide under
high pressure (pressure precipitation) or by electrolysis using insoluble
electrodes or by
crystallization (sulphates of copper, of zinc, of nickel or of thallium), by
conversion (precipitation)
into sparingly soluble compounds such as hydroxides, carbonates or basic salts
by means of chalk,
milk of lime or sodium carbonate solution.
US 6,350,420 describes, for example, the treatment of the ore particles with
mineral acids such as
sulphuric acid at high temperatures (e.g. 250-270 C) under superatmospheric
pressure (high
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pressure leaching). This gives a suspension (slurry) of the fine ore particles
in sulphuric acid, in
which the leached metals are present in the form of their salts in more or
less concentrated form.
As an alternative, the leaching of the metals from the rock can also be
effected by other methods.
The type of process used depends on a number of factors, for example on the
metal content of the
ore, on the particle size to which the crushed ore has been milled or on
apparatus conditions, to
name only a few.
In the heap leaching process, relatively coarse ore particles having a low
metal content are used.
In the agitation leaching process, finer ore particles (about 200 m) having
high metal contents are
used in the leaching process.
However, the atmospheric leaching process or the biooxidation process is also
used for dissolving
the metals from the ore. These processes are cited, for example, in US
6,350,420.
The size of the milled ore particles to be used in these processes is in the
range from about 30 to
about 250 m. Because of the small size of the particles and the large amount
of rock, a classic
filtration of the particles from the aqueous phase on filters is very costly.
Separation by the
gravitation principle in decanters by settling of the solid phase in very
large stirred vessels is
usually employed industrially. To obtain good separation and a solution of
materials of value
which is largely free of particles, stirred vessels having a diameter of 50
metres and more are used
and a plurality of these are employed in series. Large amounts of water are
required and these are
very expensive since many mines are located in regions in which water is
scarce (deserts). In
addition, it is often necessary to use filtration media which are expensive
and pollute the
environment to achieve better removal of the particles.
In hydrometallurgical plants and mines which are operated in large numbers
worldwide for the
winning of materials of value such as gold, silver, nickel, cobalt, zinc and
other metals of value,
the process steps of filtration and clarification account for a large
proportion of the capital cost of
the plant and the ongoing operating expenses.
Great efforts are therefore made to replace the abovementioned expensive
process steps by other
less capital-intensive processes. New processes of this type are carbon in
pulp processes for silver
and gold and the resin in pulp (R.I.P.) process for gold, cobalt, nickel,
manganese.
For example, US 6,350,420 describes an R.I.P. process for the winning of
nickel and cobalt. A
nickel-containing ore is treated with mineral acids in order to leach out the
materials of value. The
suspension obtained by means of the acid treatment is admixed with ion
exchangers which
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selectively adsorb nickel and cobalt. The laden ion exchangers are separated
from the suspension
by means of screens.
The ion exchangers used in US 6,350,420 are resins which are described in US
4,098,867 and
US 5,141,965. Suitable resins are accordingly Rohm & Haas IR 904, a strong
base macroporous
anion exchanger, Amberlite XE 318, Dow XFS-43084, Dow XFS-4195 and Dow XFS-
4196.
The ion exchangers described in US 4,098,867 and US 5,141,965 contain
variously substituted
aniinopyridine, in particular 2-picolylamine, groups. All ion exchangers
described there display a
heterodisperse bead diameter distribution. In US 5,141,965, the ion exchangers
display bead
diameters in the range 0.1-1.5 mm, preferably 0.15-0.7 mm, most preferably 0.2-
0.6 mm. The ion
exchangers described in US 4,098,867 display bead diameters in the range 20-50
mesh
(0.3 mm-0.850 mm) or larger diameters.
Rohm & Haas IR 904, a strong base macroporous anion exchanger, and Amberlite
XE 318 are
likewise heterodisperse ion exchangers having bead diameters in the range 0.3-
1.2 nun. In the
examples, screens having mesh openings of 30 or 50 mesh (= 300 to 600 mesh
opening) are used
to separate the laden ion exchangers from the rock particles and the leached
solution.
In the case of uranium as material of value, it is mined either by open cast
methods or
underground. In the case of underground mining, mechanical cutting and, in the
case of ores
having a low uranium content, in-situ leaching are used. The uranium present
in the ore is
separated by physical and chemical processes from the remaining rock
(liberated). For this
purpose, the ore is comminuted (crushed, fmely milled) and the uranium is
leached out. This is
achieved by means of acid or alkali with addition of an oxidant in order to
convert the uranium
from the very sparingly soluble chemical 4-valent state into the readily
soluble 6-valent form. In
this way, up to 90 percent of the urnanium present in the ore can be recovered
(see
www.nic.com.an/nip.htm).
Undesirable accompanying materials are removed from the slurry/solution
obtained in a plurality
of purification steps by means of decantation, filtering, extraction, etc.
The uranyl ions are removed from the purified solution using anion exchangers.
The first publication DE 26 27 540 (= US 4 233 272) discloses a process for
the selective
separation of uranium by means of an ion exchanger from acidic solutions which
additionally
contain nickel, iron, arsenic, aluminium and magnesium. A chelating cation
exchanger is used
here, with both uranyl UOZZ+ and U4+ ions being separated off using 8-12%
strength sulphuric acid.
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US-A 4,430,308 describes a process for the winning of uranium by means of a
heated ion
exchanger, with type II resins, for example Duolite 102 D , Ionac A-550 ,
lonac A-651 ,
IRA 410 , IlZA 910 and Dowex 2 , being able to be used for this purpose. All
of these are
heterodisperse, gel-like or macroporous ion exchangers based on styrene and
divinylbenzene as
crosslinker.
DD 245 592 Al describes a process for removing uranium by means of anion
exchangers,
characterized in that heterodisperse anion exchangers which are prepared by
reaction of
crosslinked alkyl acrylate copolymers with polyamines are used.
DD 245 368 Al relates to a process for separating off and recovering uranium,
in particular in the
form of its uranium sulphato complexes by means of heterodisperse ion
exchangers which are
prepared from (methyl)acrylic ester copolymers and polyamines from the series
of hydroxyethyl-
polyethylenepolyamines. Furthermore, DD 261 962 Al discloses a process for
preparing
heterodisperse ion exchangers having amino groups and ortho-hydroxyoxime
groups. In
Example lc of this document, uranium is present in the form of anionic uranyl
sulphato complexes
and is bound on a heterodisperse anion exchanger which has been prepared by
the process
mentioned.
DE 101 21 163 Al describes a process for preparing heterodisperse chelating
exchangers which
contain chelating groups of the formula -(CH)nNR,R2 and are used for removing
the heavy metals
or noble metals, for instance uranium. The patent DE 34 28 878 C2 discloses a
process for
recovering uranium in an extractive reprocessing procedure for irradiated
nuclear fuels. In this
process, use is made of base heterodisperse anion exchangers based on
polyalkyleneepoxypolyamine having tertiary and quaternary amino groups of the
chemical
structure R-NH+(CH3)2Cl- and R-NH+(CH3)2(C2H4OH)Cl-.
A disadvantage of the ion exchanger used in the prior art for the winning of
uranium and also those
for the winning of cobalt or nickel is the nonuniform loading of the ion
exchanger with uranyl
ions, which leads to considerable losses. Due to the ion exchangers used, the
separation of the
laden ion exchanger beads from the slurry via a screen results in further
product losses because
part of the beads is lost through the sieve because of their small diameter.
The consequences are
losses both of metal of value, for example uranium, but also of ion exchanger
beads. Furthermore,
the washing out of fine ore particles remaining from the digestion process
from the fine beads is
very time consuming and requires large amounts of water. Finally, the ion
exchangers to be used
according to the prior art cause high pressure drops and the nonuniform
loading of the ion
exchanger beads result in broad mixing zones in the eluates in the elution of
the metal of value
from the beads, which are disadvantageous for further uranium winning.
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The solution to the problem and thus subject matter of the present invention
is the use of
monodisperse, macroporous, intermediate base or strong base anion exchangers
of type I or type II
in the winning of metals of value.
The monodisperse anion exchangers to be used according to the invention are
preferably used in
hydrometallurgical processes, particularly preferably in resin in pulp
processes (R.I.P. processes)
or in in-situ leaching processes or in the work-up of water containing metals
of value.
The invention therefore also relates to a process for winning metals of value
from
hydrometallurgical processes, preferably in R.I.P. processes or in in-situ
leaching processes or for
the work-up of water containing metals of value, characterized in that
monodisperse, macroporous
intermediate base or strong base anion exchangers of type I or type II,
preferably of type II, are
used.
Compared to the ion exchangers used in the prior art, the monodisperse,
macroporous,
intermediate base or strong base anion exchangers of type I or type II to be
used according to the
invention surprisingly display significantly higher adsorption rates for the
metals of value, in
particular for uranium, low pressure drops, have small mixing zones and
require significantly
smaller amounts of water.
In a particularly preferred embodiment, the monodisperse, macroporous
intermediate base or
strong base anion exchangers of type I or type II to be used according to the
invention serve to
adsorb uranium from aqueous solutions into which it has been leached by means
of strong acids.
When leached by means of strong acids or by means of concentrated sodium
carbonate solutions,
the uranium is preferably present as the uranyl ion (UOz'), particularly
preferably as uranyl
chloride, uranyl phosphate, uranyl acetate, uranyl carbonate, uranyl sulphate
or uranyl nitrate,
among which uranyl sulphate obtainable by leaching of the uranium-containing
rock by means of
sulphuric acid is particularly preferred.
The invention therefore particularly preferably provides for the use of
monodisperse, macroporous
intermediate base or strong base anion exchangers of type I or type II, in
particular of type H, for
the adsorption of uranyl ions from the salts of uranium with strong acids or
with sodium carbonate,
particularly preferably from uranyl sulphate or uranyl carbonate.
The preparation of monodisperse ion exchangers is known to those skilled in
the art. A distinction
is made between, apart from the fractionation of heterodisperse ion exchangers
by sieving,
essentially two direct preparation methods, namely injection or jetting and
the seed feed process in
the preparation of the precursors, the monodisperse bead polymers. In the case
of the seed feed
process, a monodisperse feed which can be produced, for example, by sieving or
by jetting is used.
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For the purposes of the present patent application, the term monodisperse
refers to substances in
which the uniformity coefficient of the distribution curve is less than or
equal to 1.2. The
uniformity coefficient is the ratio of the parameters d 60 and d 10. D 60
describes the diameter at
which 60% by mass of the particles in the distribution curve are smaller and
40% by mass are
larger or equal. D 10 refers to the diameter at which 10% by mass of the
particles in the
distribution curve are smaller and 90% by mass are larger or equal.
The monodisperse bead polymer, viz. the precursor of the ion exchanger, can be
prepared, for
example, by reacting monodisperse, optionally encapsulated monomer droplets
comprising a
monovinylaromatic compound, a polyvinylaromatic compound and also an initiator
or initiator
mixture and in the case of the present invention a porogen in aqueous
suspension. To obtain
macroporous bead polymers for preparing macroporous ion exchangers, the
presence of a porogen
is absolutely necessary. Prior to the polymerization, the optionally
encapsulated monomer droplet
is doped with a (meth)acrylic compound and subsequently polymerized. In a
preferred embodiment
of the present invention, microencapsulated monomer droplets are therefore
used for the synthesis
of the monodisperse bead polymer. The various methods of preparing
monodisperse bead polymers
both by the jetting principle and by the seed feed principle are known to
those skilled in the art
from the prior art. Reference may at this point be made to US-A 4,444 961, EP-
A 0 046 535,
US-A 4,419,245 and WO 93/12167.
The functionalization of the monodisperse bead polymers obtainable according
to the prior art to
give monodisperse, macroporous anion exchangers of type I or type II is
likewise known to those
skilled in the art from the prior art.
Thus, EP-A 1 078 688 describes the preparation of monodisperse macroporous
anion exchangers
by the phthalimide process, in which
a) monomer droplets comprising at least one monovinylaromatic compound and at
least one
polyvinylaromatic compound and, in the case of the present patent application,
a porogen
and/or optionally an initiator or an initiator combination are reacted to give
a
monodisperse, crosslinked bead polymer,
b) this monodisperse, crosslinked bead polymer is amidomethylated by means of
phthalimide
derivatives,
c) the amidomethylated bead polymer is converted into an aminomethylated bead
polymer
and
d) the aminomethylated bead polymer is finally alkylated.
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In contrast to this ether/oleum variant, the preparation of monodisperse
macroporous anion
exchangers by the phthalimide process using the ester variant is known from EP-
A 0 046 535.
Here, the encapsulated bead polymer comprising macroporous, divinylbenzene-
crosslinked
polystyrene is converted without prior removal of the capsule wall into a
strongly basic anion
exchanger by the process described in US patent 3,989,650 by means of
amidomethylation using
phthalimidomethyl acetate, alkaline hydrolysis and quaternization using
chloromethane.
In an alternative embodiment, the monodisperse macroporous anion exchangers
used according to
the invention can also be prepared by the chloromethylation process described
in EP 0 051 210 B2,
in which the bead polymers are haloalkylated by means of chloromethyl methyl
ether and the
haloalkylated polymer is reacted with ammonia or primary amines such as
methylamine or
ethylamine or a secondary amine such as dimethylamine at temperatures of from
25 C to 150 C.
The monodisperse macroporous anion exchangers of type I or type II to be used
according to the
invention can be synthesized by means of these three variants.
The macroporosity required for the anion exchangers to be used according to
the invention is
obtained as indicated above by the use of porogen during the preparation of
the bead polymer
precursor. Suitable porogens are organic solvents which do not readily
dissolve or swell the
polymer obtained. Examples are hexane, octane, isooctane, isododecane, methyl
ethyl ketone,
butanol or octanol and their isomers. Porogens are in particular organic
substances which dissolve
in the monomer but do not readily dissolve or swell the polymer (precipitants
for polymers), for
example aliphatic hydrocarbons (Farbenfabriken Bayer DBP 1045102, 1957; DBP
1113570,
1957).
As an alternative to aliphatic hydrocarbons, it is also possible, according to
US-A 4 382 124, to use
alcohols having 4 to 10 carbon atoms as porogens for preparing monodisperse,
macroporous bead
polymers based on styrene-divinylbenzene. Furthermore, an overview of the
preparative methods
for macroporous bead polymers is given there.
The distinction between type I and type rI anion exchangers has been described
in
US-A 4,430,308. For the purposes of the invention, type I resins are resins
whose adsorbing sites
are quaternary ammonium groups which are substituted by alkyl groups,
preferably by CI-C4-alkyl
groups, particularly preferably by methyl groups.
In contrast thereto, type II resins are ones in which the quaternary ammonium
groups have not only
alkyl group(s) but also at least one hydroxyalkyl group, preferably a hydroxy-
Cl-C4-alkyl group.
The type II resins are preferably ones which have
methylenehydroxyalkyldimethylammonium
groups as functional groups, with the hydroxyalkyl group having one or two
carbon atoms. The
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type II anion exchangers which are preferably used according to the invention
can be prepared by
means of the three above-described variants using tertiary amines, preferably
dimethylethanol-
amine or dimethylmethanolamine, as amine.
Metals of value to be isolated according to the invention by means of the
monodisperse,
macroporous anion exchangers are preferably metals of main groups III to VI
and of transition
groups 5 to 12 of the Periodic Table of the Elements. Preference is given to
winning mercury, iron,
titanium, chromium, tin, lead, cobalt, nickel, copper, zinc, cadmium,
manganese, uranium,
bismuth, vanadium, the platinum group elements ruthenium, osmium, iridium,
rhodium, palladium,
platinum and also the noble metals gold and silver. According to the
invention, particular
preference is given to using the monodisperse, macroporous anion exchangers
for winning
uranium.
Preferred processes for the use of the monodisperse, macroporous anion
exchangers to be used
according to the invention are resin in pulp processes or in-situ leaching
processes, particularly
preferably in-situ leaching processes, or the work-up of any water containing
metals of value.
The monodisperse, macroporous anion exchangers to be used according to the
invention are used
in appropriate plants of exploration companies. In the case of the winning of
uranium which is
particularly preferred according to the invention, the pages
http://www.uraniumsa.org/processing/insitu.leaching.htm,
http://www.nrc.gov/materials/fuel-
cycle-fac/ur-milling.htm or IAEA-TECDOC-1239, "Manual of acid in situ leach
uranium mining
technology" of the IAEA (International Atomic Energy Agency) of August 2001
give examples of
possible configurations of apparatus of existing mines which employ the in-
situ leaching process.
As indicated above, the monodisperse, macroporous anion exchangers of type I
or type II, in
particular of type II, to be used according to the invention surprisingly
display a significantly
higher adsorption rate for the abovementioned metals of value, in particular
for the winning of
uranium from in-situ leaching processes, compared to the prior art.
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Examples
Example 1
a) Preparation of the monodisperse, macroporous bead polymer based on styrene,
divinylbenzene and ethylstyrene
3000 g of deionized water are placed in a 101 glass reactor and a solution of
10 g of gelatin, 16 g
of disodium hydrogenphosphate dodecahydrate and 0.73 g of resorcinol in 320 g
of deionized
water is added and mixed in. The temperature of the mixture is brought to 25
C. A mixture of
3200 g of microencapsulated monomer droplets having a narrow particle size
distribution and
comprising 3.6% by weight of divinylbenzene and 0.9% by weight of ethylstyrene
(used as
commercial isomer mixture of divinylbenzene and ethylstyrene containing 80% of
divinylbenzene), 0.5% by weight of dibenzoyl peroxide, 56.2% by weight of
styrene and 38.8% by
weight of isododecane (industrial isomer mixture having a high proportion of
pentamethylheptane)
is subsequently added while stirring, with the microcapsule comprising a
formaldehyde-cured
complex coacervate of gelatin and a copolymer of acrylamide and acrylic acid,
and 3200 g of an
aqueous phase having a pH of 12 are added. The mean particle size of the
monomer droplets is
460 Am.
The mixture is polymerized while stirring by increasing the temperature
according to a temperature
programme commencing at 25 C and finishing at 95 C. The mixture is cooled,
washed on a 32 ICm
sieve and subsequently dried at 80 C under reduced pressure. This gives 1893 g
of a spherical
polymer having a mean particle size of 440 m, a narrow particle size
distribution and a smooth
surface.
The polymer is chalky white in appearance and has a bulk density of about 370
g/l.
lb) Preparation of the amidomethylated bead polymer
2400 ml of dichloroethane, 595 g of phthalimide and 413 g of 30.0% strength by
weight formalin
are placed in a reaction vessel at room temperature. The pH of the suspension
is adjusted to 5.5-6
by means of sodium hydroxide. The water is subsequently removed by
distillation. 43.6 g of
sulphuric acid are then added. The water formed is removed by distillation.
The mixture is cooled.
At 30 C, 174.4 g of 65% strength oleum is added, followed by 300.0 g of
monodisperse bead
polymer prepared according to process step la). The suspension is heated to 70
C and stirred at
this temperature for a further 6 hours. The reaction liquor is taken off,
deionized water is added
and residual amounts of dichloroethane are removed by distillation.
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Yield of amidomethylated bead polymer: 1820 ml
Elemental composition determined by analysis: carbon: 75.3% by weight;
hydrogen: 4.6% by
weight; nitrogen: 5.75% by weight.
lc) Preparation of the aminomethylated bead polymer
851 g of 50% strength by weight sodium hydroxide solution and 1470 ml of
deionized water are
added to 1770 ml of amidomethylated bead polymer from Example lb) at room
temperature. The
suspension is heated to 180 C and stirred at this temperature for 8 hours.
The bead polymer obtained is washed with deionized water.
Yield of aminomethylated bead polymer: 1530 ml
The total yield, extrapolated, is 1573 ml
Elemental composition determined by analysis: carbon: 78.2% by weight;
nitrogen: 12.25% by
weight; hydrogen: 8.4% by weight.
Number of mol of aminomethyl groups per litre of aminomethylated bead polymer:
2.13
Number of mol of aminomethyl groups in the total yield of aminomethylated bead
polymer: 3.259
A statistical average of 1.3 hydrogen atoms per aromatic ring originating from
the styrene and
divinylbenzene units are replaced by aminomethyl groups.
1d) Preparation of a monodisperse, macroporous anion exchanger having
dimethylamino-
methyl groups = type I
1995 ml of deionized water and 627 g of 29.8% strength by weight formalin
solution are added to
1330 ml of aminomethylated bead polymer from Example l c) at room temperature.
The mixture is
heated to 40 C. It is subsequently heated to 97 C over a period of 2 hours. A
total of 337 g of 85%
strength by weight formic acid are added at this temperature. The pH is
subsequently set to 1 by
means of 50% strength by weight sulphuric acid over a period of 1 hour. At pH
1, the mixture is
stirred for another 10 hours. After cooling, the resin is washed with
deionized water and freed of
sulphate and converted into the OH form by means of sodium hydroxide solution.
Yield of resin having dimethylamino groups: 1440 ml
The total yield, extrapolated, is 1703 ml
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The product contains 2.00 mol of dimethylamino groups/litre of resin.
The total number of mol of dimethylamino groups in the total yield of product
having
dimethylamino groups is 3.406.
Example 2
Preparation of a monodisperse intermediate base macroporous anion exchanger
having
dimethylaminomethyl groups and trimethylaminomethyl groups = type I
1220 ml of bead polymer bearing dimethylaminomethyl groups from Example ld),
1342 ml of
deionized water and 30.8 g of chloromethane are placed in a reaction vessel at
room temperature.
The mixture is heated to 40 C and stirred at this temperature for 6 hours.
Yield of resin bearing dimethylaminomethyl groups and trimethylaminomethyl
groups: 1670 ml
The extrapolated total yield is 2331 ml .
Of the nitrogen-containing groups of the product, 24.8% are present as
trimethylaminomethyl
groups and 75.2% are present as dimethylaminomethyl groups.
The utilizable capacity of the product is: 1.12 mol/litre of resin.
Stability of the resin in the original state: 98 perfect beads in 100
Stability of the resin after the rolling test: 96 perfect beads in 100
Stability of the resin after the swelling stability test: 98 perfect beads in
100
94 per cent by volume of the beads of the final product have a size in the
range from 0.52 to
0.65 mm.
Example 3
Preparation of a monodisperse strong base macroporous anion exchanger having
hydroxyethyldimethylaminomethyl groups = type II
1230 n-A of the resin having dimethylaminomethyl groups prepared as described
in Example ld)
and 660 ml of deionized water are placed in a reaction vessel. 230.5 g of 2-
chloroethanol are added
thereto over a period of 10 minutes. The mixture is heated to 55 C. A pH of 9
is set by pumping in
20% strength by weight sodium hydroxide solution. The mixture is stirred at pH
9 for 3 hours, the
pH is subsequently set to 10 by means of sodium hydroxide solution and the
mixture is stirred at
pH 10 for a further 4 hours. After cooling, the product is washed with
deionized water in a column
and 3 bed volumes of 3% strength by weight hydrochloric acid are then filtered
through.
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Yield: 1980 ml
The utilizable capacity of the product is: 0.70 mol/litre of resin.
Stability of the resin in the original state: 96 perfect beads in 100
Stability of the resin after the rolling test: 70 perfect beads in 100
Stability of the resin after the swelling stability test: 94 perfect beads in
100
94 per cent by volume of the beads of the end product have a size in the range
from 0.52 to
0.65 mm.
Example 4
Preparation of a heterodisperse, strong base macroporous anion exchanger
having
trimethylammonium groups based on styrene-divinylbenzene according to the
prior art
4a) Preparation of the bead polymer - use of the initiator dibenzoyl peroxide
1112 ml of deionized water, 150 ml of a 2% strength by weight aqueous solution
of
methylhydroxyethylcellulose and 7.5 gram of disodium hydrogenphosphate x 12
H20 are placed in
a polymerization reactor at room temperature. The total solution is stirred at
room temperature for
one hour. The monomer mixture comprising 59.61 g of 80.53% strength by weight
divinylbenzene,
900.39 g of styrene, 576 g of isododecane and 7.70 g of 75% strength by weight
dibenzoyl
peroxide is subsequently added. The mixture is firstly left to stand at room
temperature for
minutes and is then stirred at room temperature at a stirring speed of 2000
rpm for 30 minutes.
The mixture is heated to 70 C, stirred at 70 C for a further 7 hours, then
heated to 95 C and stirred
20 at 95 C for a further 2 hours. After cooling, the bead polymer obtained is
filtered off and washed
with water and dried at 80 C for 48 hours.
The diameter of the beads is in the range from 0.32 to 0.71 mm.
4b) Preparation of the amidomethylated bead polymer
1331 ml of 1,2-dichloroethane, 493.9 g of phthalimide and 347.4 g of 29.6%
strength by weight
formalin are placed in a reaction vessel at room temperature. The pH of the
suspension is adjusted
to 5.5-6 by means of sodium hydroxide. The water is subsequently removed by
distillation. 36.2 g
of sulphuric acid are then added. The water formed is removed by distillation.
The mixture is
cooled. At 30 C, 132.3 g of 65% strength oleum is added, followed by 317.1 g
of heterodisperse
bead polymer prepared according to process step 4a). The suspension is heated
to 70 C and stirred
at this temperature for a further 6.5 hours. The reaction liquor is taken off,
deionized water is
added and residual amounts of dichloroethane are removed by distillation.
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Yield of amidomethylated bead polymer: 1410 ml
Elemental composition determined by analysis: carbon: 76.8% by weight;
hydrogen: 5.0% by
weight; nitrogen: 5.4% by weight.
4c) Preparation of the aminomethylated bead polymer
1515.75 g of 24.32% strength by weight sodium hydroxide solution are added to
1385 ml of
amidomethylated bead polymer from Example 4b) at room temperature. The
suspension is heated
to 180 C over a period of 2 hours and stirred at this temperature for a
further 8 hours.
The bead polymer obtained is washed with deionized water.
Yield of aminomethylated bead polymer: 1200 ml
Elemental composition determined by analysis: carbon: 79.3% by weight;
nitrogen: 11.2% by
weight; hydrogen: 8.4% by weight; balance oxygen.
Aminomethyl group content of the resin: 2.34 mol/l
A statistical average of 1.17 hydrogen atoms per aromatic ring originating
from the styrene and
divinylbenzene units are replaced by aminomethyl groups.
4d) Preparation of the heterodisperse, strong base, macroporous anion
exchanger having
trimethylammonium groups
1160 ml of aminomethylated bead polymer from Example 4c) are introduced into
1950 ml of
deionized water in an autoclave at room temperature. 501.6 g of chloromethane
are added and the
suspension is heated to 40 C. At 40 C, the suspension is stirred at a stirring
speed of 200 rpm for a
further 16 hours. The autoclave is cooled and vented. The resin is filtered
off on a sieve, washed
with water and transferred to a column. 200 ml of 5% strength by weight
aqueous sodium chloride
solution are added while swirling. The resin is subsequently classified to
remove soluble and solid
constituents.
Volume yield: 1620 ml
Stability of the resin in the original state: 99% of whole beads
Stability of the resin after the rolling test: 96% of whole beads
Stability of the resin after the swelling stability test: 98% of whole beads
The diameter of the beads is in the range from 0.35 to 0.85 mm.
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Example 5
Preparation of a monodisperse, strong base macroporous anion exchanger having
trimethylammonium groups based on styrene-divinylbenzene
1513 ml of deionized water are placed in a reactor. 900 ml of aminomethylated
bead polymer from
Example lc) and 263 ml of 50% strength by weight sodium hydroxide solution are
added thereto at
room temperature. 357 g of chloromethane are subsequently added and the
suspension is heated to
40 C. The suspension is stirred at 40 C for 16 hours and subsequently cooled
to room temperature.
The suspension is poured onto a sieve and subsequently washed with deionized
water. The anion
exchanger is then introduced into a column provided with a glass frit. 1500 ml
of 3% strength by
weight aqueous HCl are filtered through. The anion exchanger is then
classified by means of water
to remove solid and dissolved particles.
Volume yield: 1560 ml
Stability of the resin in the original state: 99% of whole beads
Stability of the resin after the rolling test: 97% of whole beads
The diameter of the beads is in the range from 0.57 to 0.67 mm.
Example 6
Determination of the uptake capacity of a heterodisperse, strong base
macroporous anion
exchanger having trimethylammonium groups based on styrene-divinylbenzene
500 g of a zinc(lI) chloride solution which has been adjusted to pH 1 by means
of hydrochloric
acid are placed in a polyethylene bottle. The solution contains 4.2 g of zinc
per litre of solution.
10 ml of a heterodisperse, strong base macroporous anion exchanger having
trimethylammonium
groups based on styrene-divinylbenzene are added to the solution. The mixture
is stirred at room
temperature for 24 hours.
Samples are taken after 5 hours and 24 hours and analysed to determine their
zinc content.
Sample taken after 5 hours: zinc content = 4.2 g of zinc per litre of solution
- based on the initial
concentration, 0% of zinc was taken up.
Sample taken after 24 hours: zinc content = 4.1 g of zinc per litre of
solution - based on the initial
concentration, 2.5% of zinc was taken up.
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Example 7
Determination of the uptake capacity of a monodisperse, strong base
macroporous anion
exchanger having trimethylammonium groups based on styrene-divinylbenzene
500 g of a zinc(II) chloride solution which has been adjusted to pH 1 by means
of hydrochloric
acid are placed in a polyethylene bottle. The solution contains 4.2 g of zinc
per litre of solution.
ml of a monodisperse, strong base macroporous anion exchanger having
trimethylammonium
groups based on styrene-divinylbenzene are added to the solution. The mixture
is stirred at room
temperature for 24 hours.
Samples are taken after 5 hours and 24 hours and analysed to determine their
zinc content.
10 Sample taken after 5 hours: zinc content = 3.5 g of zinc per litre of
solution - based on the initial
concentration, 16.7% of zinc was taken up.
Sample taken after 24 hours: zinc content = 3.3 g of zinc per litre of
solution - based on the initial
concentration, 26.7% of zinc was taken up.
Methods of examination:
Number of perfect beads after preparation
100 beads are viewed under the microscope. The number of beads which have
cracks or display
spalling is determined. The number of perfect beads is the difference between
the number of
damaged beads and 100.
Determination of the stability of the resin after the rolling test
The bead polymer to be tested is distributed in a layer of uniform thickness
between two plastic
cloths. The cloths are placed on a firm, horizontal substrate and subjected to
20 cycles in a rolling
apparatus. One cycle consists of one forward and back movement of the roller.
After rolling, the
number of unscathed beads in 100 beads is determined on representative samples
by counting
under the microscope..
Swelling stability test
25 ml of anion exchanger in the chloride form are introduced into a column. 4%
strength by weight
aqueous sodium hydroxide solution, deionized water, 6% strength by weight
hydrochloric acid and
once again deionized water are introduced in succession into the column, with
the sodium
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hydroxide solution and the hydrochloric acid flowing downwards through the
resin and the pure
water being pumped through the resin from below. The treatment is sequenced by
means of a
control apparatus. One cycle takes one hour. 20 cycles are carried out. After
the end of the cycles,
100 beads are counted out from the resin sample. The number of perfect beads
which are not
damaged by cracks or spalling is determined.
Utilizable capacity of strong base and intermediate base anion exchangers
1000 ml of anion exchanger in the chloride form, i.e. the nitrogen atom bears
chloride as
counterion, are introduced into a glass column. 2500 ml of 4% strength by
weight sodium
hydroxide solution are filtered through the resin over a period of 1 hour. The
resin is subsequently
washed with 2 litres debasified, i.e. decationized, water. Water having a
total anion hardness of
25 degrees of German hardness is then filtered through the resin at a rate of
10 litres per hour. The
eluate is analysed to determine the hardness and also the residual amount of
silicic acid. Loading is
complete at a residual silicic acid content of > 0.1 mg/l.
The number of gram of CaO taken up by one litre of resin is determined from
the amount of water
filtered through the resin, the total anion hardness of the water filtered
through and the amount of
resin installed. The number of gram of CaO represents the utilizable capacity
of the resin in the
unit gram of CaO per litre of anion exchanger.
Volume change chloride/OH form
100 ml of anion exchanger bearing basic groups are rinsed into a glass column
by means of
deionized water. 1000 ml of 3% strength by weight hydrochloric acid are
filtered through over a
period of 1 hour and 40 minutes. The resin is subsequently washed free of
chloride with deionized
water. The resin is rinsed under deionized water in a tamping volumeter and
jiggled in until the
volume was constant - volume V 1 of the resin in the chloride form.
The resin is again transferred into the column. 1000 ml of 2% strength by
weight sodium
hydroxide solution are filtered through. The resin is subsequently washed free
of alkali with
deionized water until the eluate has a pH of 8. The resin is rinsed under
deionized water in a
tamping volumeter and jiggled in until the volume is constant - volume V2 of
the resin in the free
base form (OH form).
Calculation: V 1- V2 = V3
V3:V 1/100 = swelling change chloride/OH form in %
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Determination of the amount of basic aminomethyl groups in the
aminomethylated,
crosslinked polystyrene bead polymer
100 ml of the aminomethylated bead polymer are jiggled in on a tamping
volumeter and
subsequently rinsed into a glass column by means of deionized water. 1000 ml
of 2% strength by
weight sodium hydroxide solution are filtered through over a period of 1 hour
and 40 minutes.
Deionized water is subsequently filtered through until 100 ml of eluate
admixed with
phenolphthalein have a consumption of not more than 0.05 ml of 0.1 N(0.1
normal) hydrochloric
acid.
50 ml of this resin are admixed with 50 ml of deionized water and 100 ml of 1
N hydrochloric acid
in a glass beaker. The suspension is stirred for 30 minutes and subsequently
introduced into a glass
column. The liquid is drained. A further 100 ml of 1 N hydrochloric acid are
filtered through the
resin over a period of 20 minutes. 200 ml of methanol are subsequently
filtered through. All
eluates are collected and combined and titrated with I N sodium hydroxide
against methyl orange.
The amount of aminomethyl groups in 1 litre of aminomethylated resin is
calculated according to
the following formula: (200 - V)=20 = mol of aminomethyl groups per litre of
resin.
Determination of the degree of substitution of the aromatic rings of the
crosslinked bead
polymer by aminomethyl groups
The amount of aminomethyl groups in the total amount of the aminomethylated
resin is determined
by the above method.
The number of mol of aromatics present in the amount of bead polymer used, A
in gram, is
calculated from this amount by division by the molecular weight.
For example, 950 ml of aminomethylated bead polymer containing 1.8 mol of
aminomethyl groups
per litre are prepared from 300 gram.
950 ml of aminomethylated bead polymer contain 2.82 mol of aromatics.
1.8/2.81 = 0.64 mol of aminomethyl groups are then present per aromatic.
The degree of substitution of the aromatic rings of the crosslinked bead
polymer by aminomethyl
groups is 0.64.
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