Note: Descriptions are shown in the official language in which they were submitted.
WO 94/03648 PCT/US92/06551
BINDER COMPOSITION AND PROCESS FOR AGGLOMERATING
PARTICULATE MATERIAL
BACKGROUND OF THE INVENTION
",
The present invention relates to a novel binder
composition for agglomerating particulate materials, a novel
process for agglomerating particulate materials u,'sing said
binder composition, and to the agglomerated products produced
from said process. The process is particularly useful for
agglomerating metallic ores such as iron ore.
Agglomeration i commercially used in industries where
materials are encountered in-a form which is too finely
.15 divided for convenient processing or handling. Thus, there is
a need to upgrade the size, density and/:or uiniformity of
finely d~.vided particles for more efficient handling,
processing or recovery. Agglomeration is particularly useful
in the metal refining industry, where the concentrate ore
.~ZO' encountered is typically finely divided:
Many processes for the agglomeration of particles,
especially metallic particles, are known in the art. In the
mining industry it is common practice to'agglomexate or
25~= pelletize ffinely ground mineral ore concentrate to facilitate
shipping of the ore. After the mineral ore has been mined, it
'is frequently wet ground, though not always the case, and
screened to remove large particles which can be recycled for
further grinding: The screened mineral'ore is known in the
30 art 'as ~~concentrate~~
After screening:, a binding agent is added to the wetted
mineral ore concentrate and the binder/mineral ore composite
K is conveyed to a balling: drum or other means for',pelletizing
~,~5 the ore: The binding agent serves to hold or bind the mineral
ore together until after firing. After he balling drum
operation, the pellets are formed, but they are still wet.
1
WO 94/03648 PGT/US92/06551
2 ~. ~ 1'~ 8'~
These wet pellets are commonly referred to as "green pellets"
or "green balls". These green pellets are thereafter
transported to a kiln and heated in stages to a end
temperature of about 2400°F.
.'
For many years, bentonite clay was the binding agent of
choice in the pelletizing operations for mineral ore
concentrates. Use of bentonite as a binding agent produces
balls or pellets having a very good wet and dry strengths and
also provides a desired degree of moisture control. Use of
bentonite does,~however, have several disadvantages.
Initially,, bentonite adds to the silica content of the pellets
when the ore pellets are fired at, a temperature of 2400°F or
higher. Higher amounts of silica are not desirable because
silica decreases the efficiency of blast furnace operations
used in smelting the ore.
The use of bentonite to form pellets of mineral ore
concentrates can also add alkalis which are oxides of, for
example, sodium and potassium. The presence of arkalis in the
blast furnace causes both the pellets and coke to deteriorate
and to form scabs on the furnace wall, which increases fuel
consumption and decreases the productivity of the smelting
operation.
Organic binders have proven to be an attractive
alternative to bentonite because organic binders do not
increase the silica content of the ore and they impart
physical and mechanical properties to the pellets comparable
with those of bentonite. Organic binders also burn out during
ball firing operations thus causing an increase in the
microporosity of the pellets. Accordingly, the: pore volume
and surface/mass ratio of the formed pellets produced using
organic binders is larger than that of pellets produced using
bentonite. Due to the larger surface area and increased
permeability of the pellets produced using organic binders,
2
WO 94/03fs48 ~ ~ ~ PGT/US92/06551
the reduction of metallic oxides such as iron oxide is more
efficient than with pellets prepared with bentonite.
Examples of some commonly mentioned organic binders
include polyacrylate, polyacrylamide and copolymers thereof,
methacrylamide, polymethacrylamide, cellulose derivatives such
as alkali metal salts of carboxymethyl cellulose and
carboxymethylhydroxyethyl cellulose, poly (ethylene oxide),
guar gum, dairy wastes, starches, dextrins, wood related
products, alginates, pectins, and the like.
U. S. Patent No. 4,751,259 discloses compositions for
iron ore agglomeration which comprise 10-45% by weight of a
water-in-oil emulsion of a water soluble vinyl addition
polymer, 55-90% by weight of a polysaccharide, .001 - 10% by
weight of a water soluble surfactant and 0-15 weight % of
Borax.
U. S. Patent No. 4,948,430 discloses a binder for the
agglomeration of ore in the presence of water, which comprises
10% - 90% of a water soluble sodium carboxymethylhydroxyethyl
cellulose and 10% to 90% of sodium carbonate.
U. S. Patent No. 4,288,245 discloses pelletization of
metallic ores, especially iron ore, with carboxymethyl
cellulose and the salt of a weak acid.
U. S. Patent No. 4,863,512 relates to a binder for
metallic containing ores which comprises an alkali metal salt
.of carboxymethyl cellulose and sodium tripolyphosphate.
European Patent Application Publication No. 0 376 713
discloses a process for making pellets o~f particulate metal
ore, particularly iron ore. The process comprises mixing a
water-soluble polymer with the particular metal ore and water
and pelletizing the mixture. The water-soluble polymer may be
of any typical type, e.g., natural, modified natural or
3
CA 02141787 2004-07-08
synthetic . The mixture may optionally comprise a palletizing
a id which may be sodium citrate.
Organic binder compositions, such as those mentioned
above, are not, however, without their own disadvantages.
While they are effective binders, they generally do not impart
adequate dry strength to the pellets at economical use levels.
Thus, there is an ongoing need for economical binders with
improved properties.
l0
SUMMARY OF THE INVENTION
The present invention generally relates to a process for
agglomerating particulate material in the presence of water
which comprises mixing said particulate materia 1 with a
binding a ffective amount of at least one water soluble
polymer, and a binder enhancing effective amount of caustic to
produce a mixture, and forming said mixture int o agglomerates.
In another embodiment, the present inventi on contemplates
a binder composition useful for the agglomeration of
particulate material in the presence of water which comprises
a binding effective amount of at least one water soluble
polymer and a binder enhancing effective amount of caustic.
In another embodiment, the present invention contemplates
a process for agglomerating material comprising:
a) pretreating said particulate material with a binder
enhancing effective amount of a liquid spray of a
source of hydroxide ions;
b) mixing said pretreated particulate material with a
binding effective amount of a water-soluble polymer and
water; and
c) forming said mixture into agglomerates.
4
CA 02141787 2004-07-08
DETAILED DESCRIPTION OF THE INVENTION
The present invention generally relates to a process of
agglomerating particulate materials, especially metal
containing ores, in the presence of water. The process
comprises mixing said particulate material with a binding
effective amount of at least one polymer and a binder
enhancing effective amount of caustic to produce a mixture,
and thereafter or contemporaneously forming said mixture into
agglomerates.
In the context of the present invention, the present
inventors have found that the addition of caustic, in either
liquid Or powdered form, to the mineral ore, as an integral
4a
WO 94/03648 ~ ~ ~ R ~ PCT/US92/06551
part of the organic binder or as a separate entity,
unexpectedly provides a synergistic effect in the
pelletization process, giving the resultant pellets superior
wet drop numbers and dry crush strength compared to pellets
formed without the use of caustic. This increase in
performance obtained by the addition of caustic allows the
user to effectively reduce the amount of organic:binder
required thus significantly reducing total binder cost.
The terra "agglomerated" or "agglomeration" as used in the
contextof he present invention shall mean the'processing of
finely divided materials, whether in powder, dus'~, chip, or
other particulate form, to for:a pellets, granules, briquettes,
and the like:
The particulate material which may be agglomerated in
accordance with this present invention may be almost any
finely divided material including metallic minerals or ore.
The predominant metal component in said ore may-, be iron,
2r0 chrome, copper, nickel, zinc, lead, uranium, borium and he
dike. kiixtures of the above materials or any other metal
occurring in the free or molecularly combined material state
asa mineral, or any combination of the above, or other
metals, or metal containing ores capable of pelletization, may
2'5- be agglomerated in accordance with the present invention. The
present invention is particularly well adapted for the
agglomeration of materials containing iron, including iron ore
deposits, ore tailings,'cold and hot fines from a sinter
process or aqueous iron'ore concentrates from natural sources
30 or recovered from various processes: Iron ore,or any of a
wide variety of the'following minerals may for:a a part of the
material to be agglomerated: taconite, magnetite, hematite,
limonite, goethite, siderite, franklinite,, pyrite,
chalcopyrite, chromite, ilmenite and the like.
Minerals other than-metallic minerals which may be
agglomerated in accordance with the invention include
r'
WO 94/03648 ~ ~ ~ ~ ~ t PCTlUS92l06551
phosphate rock, talc, dolomite, limestone and the like. Still
other materials which may be agglomerated in accordance with
the present invention include fertilizer materials such as
.potassium sulfate, potassium chloride, double sulfate of
potassium and magnesium; magnesium-oxides animals feeds such
..
as calcium phosphates: carbon black: coal fines; catalyst
mixtures; glass batch mixtures; borates, tungsten carbide;
refractory gunning mixes; antimony, flue dust from, for
example, power generating plants, solid fuels such as coal,
coke or charcoal, blast furnace fines and the like.
The water-soluble polymers) useful in the present
invention include but are not limited to:
(1) Water-soluble natural polymers such as guar gum,
starch, alginates, pectins, xanthan gum, dairy wastes, wood
related products, lignin and the like;
(2), Modified natural polymers such as guar derivatives
(e. g. hydroxypropyl guar, carboxymethyl guar,
carboxymethylhydroxypropyl guar), modified starch (e. g.
anionic starch, cationic starch), starch derivatives (e. g.
dextrin) and cellulose derivatives such as alkali metal salts
of carboxymethyl cellulose, hydroxyethyl cellulose,
hydroxypropyl cellulose, carboxymethylhydroxyethyl cellulose,
methyl cellulose, lignin derivatives (e. g. carboxymethyl
lignin) and the like; and/or
(3) Synthetic polymers (e.g. polyacrylamides such as
partially hydrated polyacrylamides; polyacrylates and
copolymers thereof; polyethylene oxides, and the like).
The foregoing polymers may be used alone or in various
combinations of two or more polymers. Water-soluble anionic
polymers are a preferred class of polymers to be employed in
the present invention.
Preferred polymers for use in the present invention are
alkali metal salts of carboxymethyl cellulose. Any
substantially water-soluble alkali metal salt of carboxymethyl
cellulose may be used in this invention. The sodium salt is,
6
PCT/US92/06551
WO 94/03648
however, preferred. Alkali metal salts of carboxymethyl
cellulose, more particularly sodium carboxymethyl cellulose,
are generally prepared from alkali cellulose and the
respective alkali metal salt of monochloroacetic acid.
Cellulose which is used in the manufacture of sodium
,.
carboxymethyl cellulose is generally derived from wood pulp or
cotton linters, but may be derived from other sources such as
sugar beet pulp, bagasse, rice hulls, bran, microbially-
derived cellulose, and waste.cellulose e.g. shredded paper).
The sodium carboxymethyl cellulose used in the present
:invention generally has a degree of substitution ',(the average
number of carboxymethyl ether groups per repeating
anhydroglucose chain unit of the cellulose molecule) of from
about 0.4 to about 1.5, more preferably about 0.6, to about
0.9, and most preferably about 0.7: Generally the average
degree of polymerization of,the cellulose furnish is from
about 50 to about 4000: Polymers having a degree of
polymerization on the higher end of the, range are preferred.
It is more preferred to use sodium carboxymethyl'cellulose
having a Brookfield.viscosity in a 1% aqueous solution of more
than'2000 cps at:30 rpm, spindle #4. Still more preferred is
sodium carboxy~nethyl cellulose having a 8rookfield viscosity
in a i% aqueous solution of more than about 4,004 cps at 30
rpm spindle #4.
A series of commercially available binders containing
sodium carboxymethyl cellulose especially useful in the
present nvention is marketed by the Dreeland, Inc. of
Virginia, lit, Denver;, CO, and Akzo Chemicals ofnAmersfoort,
the Netherlands,; under the trademark Peridu~.
The "binding effective amount of polymer" will vary
depending upon numerous factors known to 'the skilled artisan.
Such factors include, but are not limited to, the type of
~5 particulate material to be agglomerated or pelletized, the
moisture'content of the particulate material, particle size,
the agglomeration equipment utilized, and the desired
WO 94/03648 ~ ~ ~ ~~ PCT/US92/06551
properties of the final product, e.g. dry strength (crush ,
drop number, pellet size and smoothness. Though not limiting,
a binding effective amount of polymer will typically be in the
range of between about 0.01% to 1% by weight based on the dry
weight of the mixture of particulate material, polymer and '
caustic. Preferably, the polymer is present in a range of
between about 0.01 to 0.4% by weight, and most preferred,
about 0.04%.
As used herein, the term "caustic" shall mean any source
of hydroxide ions (OH-) including, but not limited to sodium
hydroxide, potassium hydroxide, ammonium hydroxide, calcium
hydroxide, barium hydroxide, magnesium hydroxide, mixtures
thereof and the like. Sodium hydroxide, commonly known as
caustic soda, is the most preferred caustic.
A "binder enhancing effective amount of caustic" depends
on.the same factors as does the binding effective amount of
polymer. Without wishing to be bound to any particular
ZO limitation, a binding effective amount of caustic will
typically be in the range of between about .004% to .15% by
weight based on the dry mixture of particulate material,
polymer and caustic. Preferably, caustic ~is present in the
range of between about .O1% to .04% by weight, and most
preferred at about .03% by weight.
In another embodiment, the present invention contemplates
a process of agglomerating particulate material in the
presence of water which comprises mixing said particulate
material with between about 0.01% to 1% by weight of at least
one water soluble polymer selected from hydroxyethyl
cellulose, alkali metal salts of carboxymethyl cellulose,
methyl cellulose, methylhydroxyethyl cellulose and mixtures
thereof, and .004% to .15% by weight of sodium hydroxide to
produce a mixture, and forming said mixture into agglomerates.
8
WO 94/03648 2 ~ ~ ~ R ~ PGTlUS9Z/06551
In still another embodiment, the present invention
contemplates a process of agglomerating iron ore wherein said
ore is mixed with between about 0.01 to 0.4% by weight of an
alkali metal salt of carboxymethyl cellulose, from about 0.01
to .04% by weight sodium hydroxide, and from about 0.02-0.5
wt% (based on dry ore) of soda ash, to produce a mixture, and
forming said mixture into agglomerates.
Agglomerated particulate materials formed from any of the
l0 foregoing processes is also deemed to be within the scope of
the present invention.
The present invention also contemplates a binder
composition useful for the agglomeration of particulate
materials. The binder composition comprises a binding
effective amount of at least one water soluble polymer, and a
binder enhancing effective amount of caustic.
In a preferred embodiment, the present invention
contemplates a binder composition which comprises between
about 10% to 95% by weight of a water soluble polymer and
between about 2% to 50% by weight of caustic (wt% binder
composition).
In another preferred embodiment, the present invention
contemplates a binder composition useful for the agglomeration
of iron ore in the presence of water which comprises between
about 45% to 95% by weight of a water-soluble alkali metal
salt of carboxymethyl cellulose and l0% to 40% by weight of
sodium hydroxide.
In yet another embodiment, the present invention
contemplates a binder composition whichcomprises between
about 50% to 80% by weight of an alkali metal salt of
carboxymethyl cellulose, between about 10% to 35% by weight of
caustic, and between about 2% to 20% bx weight of a salt of a
weak acid, such as sodium citrate and or soda ash.
9
WO 94/03648 ~~ ' PCT/US92/06551
The binder composition of the present invention may also
contain other substances, for instance, those that are formed
as by-products in the preparation of the alkali metal salt of
carboxymethyl cellulose, such as sodium chloride and sodium
glycolate, as well as other polysaccharides or synthetic
",
water-soluble polymers and other "inorganic salts" (for want
of a better term sodium carbonate, sodium citrate, and the
Like are referred to as "inorganic salts" herein). Exemplary
polysaccharides include,'e:g., hydroxyethyl cellulose,.
hydroxypropyl cellulose, carboxymethylhydroxyethyl cellulose ,
methyl'cellulose, hydroxypropyl methyl cellulose, guar,
hydroxpropyl guar and sugar. beet pulp, and the like.
Exemplary synthetic water-soluble polymers include partially
hydrated polyacrylamide, polyvinyl alcohol, styrene/maleic
anhydride copolymers, and polyacrylate and copolymers thereof,
etc. Exemplary inorganic salts include; e. g. the salts
described by Roorda in U. S. Patent Nos.4,288,245 and
4,597,797 such as sodium citrate, soda ash, and'the like.
The ratiosof polymer, e.g. alkali metal salt of
carboxymethyl cellulose, caustic and water to particulate
material, e.g.:concentrated ore are'dependent on various
factors including the agglomeration method used, the material
to be agglomerated.and th,e desired properties of the
agglomerates to be prepared: A,person of ordinary skill in
the art can readily detenaine the specific amounts that will
be most suitable for individual circumstances.: Pelletization
is generally carried out using;the binder comp4sition in an
amount of from about 0.0044% to about 0.44%, preferably from
about '0.022% to about 0.22% (by weight of the total dry
mixture), of the binder composition and about 2% to about 20%,
preferably about 5% to about 15%, water, by weight of the
total dry mixture. In addition to the binder composition,
clays'such as bentonite clay may be used in pelletization.
The total amount of these clays will depend on the user's
objectives, but will generally be less than 0.22%, based on
the weight of the total dry mixture:
WO 94/03648 2 ~ ~ 1 ~ ~ ~'~ PGT/US92/06551
Any known method for forming dry pellets or particles can
be used to prepare the agglomerates of this invention. For
instance, the concentrated ore may be agglomerated into
particles or agglomerates by rotating the concentrated ore
powder in a drum or disc with a binder and water, followed by
drying and firing. Agglomerates can also be formed by '~
briquetting, nodulizing, or spray drying.
Addition of the binder composition constituents may be
carried out in any manner commonly applied in the art. For'
instance, the binder constituents may be mixed as solid matter
with the concentrated ore in a dry or liquid form or as an
emulsion or dispersion. Further, they may be simultaneously,
successively or alternatively added to the concentrated ore
before or during the pelletizing treatment. In a preferred
method, Ziquid caustic is sprayed on moist concentrated ore
resulting from the aforementioned separation process, which
has all but about 10 wt% of the water removed by, e.g.
rotating disc filter. At a sufficient,point upstream from the
agglomerating drum or disc, the polymeric binder composition
is applied so that the binder components and concentrated ore
are well mixed aad adequately hydrated prior to being formed w
into green pellets. As non-limiting ranges, the water content
should generally be in the range of about 4 to 30 wt% based on
the weight of dry particulate matter and most preferably
between about 7 and 12 wt%.
Other substances may also be optionally added to the
binder composition of the present invention. For example, in
iron ore pelletizing operations, small amounts of flux, e. g.,
limestone or dolomite may also be added to enhance mechanical
properties of the pellets. The flux also helps to reduce the
dust level in the indurating furnace when the pellets are
fired. Olivine, serpentine, magnesium and similar minerals
may be used to improve metallurgical properties of the
pellets.
11
WO 94/03648 2, ~. ~ ~~ ~ PCT/US92/06551
Drying the wet balls and. firing the resultant dry balls
may be carried out as one continuous or two separate steps.
The important factors are that the balls must be dry prior to
' firing as the balls will degrade or spall if fired without
first drying them. It is therefore preferred that the balls
."
be heated slowly to a temperature of. at least about 2200'F,
preferably to at least about 2400°F and then fired at that
temperature. In another embodiment, they are dried at low
temperatures, preferably by heating, or alternatively, under
ambient conditions, and then fired at a temperature of at
least about 2200'F, more preferably at about 2400'F. Firing
is carried out for a sufficient period of time to bond the
small particles-into-pellets with enough strength, to enable
transportation and/or further handling, generally'about 15
minutes to about 3 hours.'
The, process of the present invention; is preferably
employed with concentrated iron ore. This process' is also
suitablefor non-ferrous concentrated ores such a's ores of
zinc, lead, tin, nickel and chromium and oxidic materials such
as silicates and quartz, and sulphidicmaterials.' As a
practical matter, this .invention is intended foruse in
binding the concentrated ores which result-from separation of
the host rock from the ore removed from the ground. However,
it can also be used to bind natural ores.
The pellets resulting from this'process are dry, hard
agglomerates having sizes-that are suitable for,''e. g.
shipping, handling, sintering,-etc. Pellets generally have
30. an average diameter of about i/4 to about l inch, preferably
about 1/2 inch. Pellet size~is generally a function of the
user and operator's preference, more than of binding ability
of the compositions of this invention and~virtually any size
pellet desired by blast furnace operations and mine operations
:35: can be prepared:
WO 94/03648 PCT/US92/06551
The invention is further described by the following non-
limiting examples. For the purpose of characterizing the
agglomerates formed, use is made of the following procedure
and test protocol.
..
AGGLOMERATE FORMATION
The process was begun by placing 2500 grams (calculated
as dry weight) of iron ore concentrate (moisture content
approximately 9 to 10 wt. %) into a Mullen Mixer (Model No. 1
Cincinnati Muller, manufactured by National Engineering Co.).
Caustic was thereafter evenly sprayed on the iron ore in
liquid form, diluted from either a 10 Normal solution or
sodium hydroxide pellets (97~%), both purchased from Fisher
Scientific. The addition rate of the diluted caustic was
carefully monitored and represented in the examFles as pounds
dry caustic added per long ton dry concentrate (#/LTDC).
After caustic addition, polymer is then added to the
mixer and spread evenly over the iron ore concentrate. If a
mixture of polymers was used, the mixture was premixed by hand
prior to addition to the muller mixer. The loaded mixer was
run for three (3) minutes to evenly distribute the polymer.
The resulting concentrate mixture was screened to remove
particles smaller than those retained on an 8 mesh wire screen.
A balling disc fabricated from an airplane tire (approx.
16" diameter) driven by a motor having a 60 RPM rotational
speed was employed to produce green balls of the concentrate
mixture. Pellet "seeds" were formed by placing a small
portion of the screened concentrate mixture in the rotating
balling tire and adding atomized water to initiate seed
growth. As the size of the seed pellets..approached 4 mesh,
they were removed from the balling disc and screened. The
seed pellets with a size between 4 and 6 mesh were retained.
This process was repeated if necessary until 34 grams of seed
pellets were collected.
13
WO 94/03648 2, ~~" ~ ~~ ~ ~ PCf/US92/06551
Finished green balls were;produced by placing the 34
grams of seed pellets of size between 4 and 6 mesh into the
rotating tire of the balling disc and adding portion of the
.remaining concentrate mixture from the muller mixer over a 4
minute growth period. Atomized water was added if necessary.
M
When the proper size was achieved (-0.530 inch, +0.500 inch)
concentrate mixture addition ceased and the pellets were
allowed a 30 second finishing roll. The agglomerated pellets
were removed from the disc, screened to -0.530, +0.500 inch
size and stored in an air-tight container until they were
tested.
Test Protocol
Wet DroQ Number was determined by repeatedly dropping two
groups of ten (l0) pellets each from an 18 inch height to a
steel plate until a crack appeared on the surface of each
pellet. The number of drops xequired to produce a crack on
the surface of each pellet was recorded. The average of all
pellets was taken to determine the drop number of each
20 agglomerated mixture.
Crush Strength was determined by drying twenty (20)
pellets of each agglomerated mixture to measure the moisture
content. The dry pellets were then individually subjected to
a Chatillon Spring Compression Tester, Model LTCM,(25 pound
range) at a loading rate of O.l inch/second. The dry strength
report for each agglomerate mixture is the average cracking
pressure of the twenty pellets.
The following samples demonstrate processes and the
binders of the present invention employing various polymers
with sodium hydroxide and other OH', as binding agents for
particulate material, which is iron ore unless otherwise
specified.
14
WO 94/03648 ~ "~ ~ ! ~'~ ~ *~ PCT/US92/06551
.
Example 1
In this example,a pure sodium
carboxymethyl
cellulose
(CMC) polyme r binderwas employed (Peridu~30oZ)with
and
without the additionof caustic. Table l, below
clearly shows
that the per formanceof the pure CMC binder tremendously
is
improved by the addition ic.
of caust
TABLE 1
PURE CMC NaOH Moisture Wet Drop Dry Crush
#/LTDC #/LTDC ( ~s )
1.0 ___ 9.9 8.2 5.3
1.0 .12 10.3 10.5 7.7
1.0 .24 10.1 11.1 10.6
1.0 1.2 10.0 9.5 '11.9
1.0 2.4 9.7 7.3 8.8
1.0 4.0 9.2 5.6 8.0
# = Pounds
LTDC = Long ton dry concentrate
The data of Table l clearly show that the perfonaance of pure
CMC is greatly enhanced by the addition of NaOH. Tn this
case, there is an optimum level of NaOH addition at between
about .24 to l.2 #/LTDC. When excessive amounts of caustic
are added, the wet drops start to decrease, probably from
binder deterioration at higher pH levels.
example 2
A technical grade up to out 25% salt
CMC containing ab
byproducts (Peridur 200~)was also tested and without the
with
addition of caustic. Table 2, below, contains the data.
TABLE 2
Technical
Grade CMC NaOH Moisture Wet Drops Dry Crush
#/LTDC #LTDC C ~s )
~
,g0 ___ 10.2 6.6 1.7
.90 .12 10:5 7.9 2.1
.90 .24 10.4 8.5 3.2
.90 1.2 10.1 8.9 7.5
.90 2.4 10.1 8.4 7.2
WO 94!03648 ~ ~ ~ ~ ~ ~ ~ PCT/US92/06551 '-
The data clearly shows that the addition of caustic greatly
improves the performance of the technical grade CMC. Like the
pure grade CMC of Example 1, there is an optimum level of
caustic addition wherein product performance peaks, and
thereafter slowly deteriorates beyond optimum addition levels.
Examt~le 3
A CMC/soda ash combination was employed with and without
the addition of NaOH. The CMC/soda ash combination consists
of about 70 to 85% technical grade CMC and 15-30% soda ash.
The data obtained is compiled in Table 3, below.
TABLE 3
Technical Grade
CMC/Soda Ash Add'n NaOH Moisture Drop # Dry
Crush
#/LTDC #/LTDC
(lbs)
Peridu~ 2.15 1.06 --- 10.0 7.1 3.7
2.15 ~ 1.06 .12 10.0 7.5 5.0
2.15 1.06 .24 10.2 9.0 5.8
2.15 1.06. 1.2 10.0 8.2 7.8
2.15 1.06 2.4 9.9 7.0 7.4
Peridu~3.15 1.0 --- 9.5 4.6 2.2
3.15 1.0 .24 9.7 5.4 5.2
3.15 1.2 --- 9.5 5.0 3.0
3.15 1.2 .24 9.? 6.4 7.2
Periduz~3.30 1.0 --- 9.4 4.3 2.7
3.30 1.0 .24 9.6 4.7 5.2
3.30 1.2 -- 9.2 4.5 4.2
3.30 1.2 .24 9.6 6.1 6.7
*Periduz~ 2.15, Peridu~3.15 and Peridu~3.30 are binder
40. compositions commercially available from Dreeland, Inc.,
Virginia, MN, Denver CO, and Akzo Chemicals, Amersfoort, the
Netherlands.
The data clearly show that in every instance of caustic
addition, there was an improvement in the pellet quality as
compared to the pellets formed with no caustic addition.
16
WO 94/03548 ~ ~ ~ ~ ~ ~ PCT/US92/06551
Example 4
In this trial, applicants tested a series of anionic
polymers, including polymers of polyacrylamide (PL1400~).
POLYACRYLATE (FP 1000 , CM GUAR carboxymethyldihydroxypropyl
cellulose (CMDHPC), carboxymethylhydroxyethyl cellulose
M
(CMHEC); and, Stabilos~ LV, a carboxymethyl starch (CM
Starch) with and without caustic addition. The data is
tabulated in Table 4 below.
TABLE 4
Product Add'n NaOH Moisture Drop # Dry
Crush
#/LTDC #/LTDC
(lbs)
PAM (PL 1.1 --- 14.8 5.5 1.6
1400)~
PAM (PL 1.1 .24 11.3 6.9 1.9
1400)
PAM (PL 1.1 1.2 11.0 7.2 3.4
1400)
PAA (FP 1.0 ._- 9.1 2.9 2.5
10f~)
PAA (FP 1:0 1.2 9.3 2.9 5.3
100)
CM-GUAR 1.0 --- 20.0 7.0 1.7
CM-GUAR 1.0 .12 10.2 8.8 2.3
CM-GUAR 1.0 .24 10:1 6.9 2.?
CM=GUAR 1.0 .43 9.9 7.7 3.1
CM-GUAR 1.0 .72 9.9 3.2 2.3
CM-GUAR 1.0 1.2 9.4 2.3 2.0
CMDHPC 1.0 --- 8.9 2.7 1.3
CMDHPC 1.0 .24 9.1 2.6 1.7
,
CMHEC 1.0 --_ 9.2 3.6 1.4
CMHEC 1.0 .24 9.6 4.2 2.4
SEC 1.0 1.2 9:5 3.5 3.6
CM-Starch 2.0 --- 9.7 3.3 3.3
CM-Starch 2.0 .48 9.8 4.3 7.1
* PL1400'~ polyacrylamide commercially available from
is a
Stockhaus en, Inc.
* FP100~ polyacrylate
is a commercially
available
from
Polyacryl Inc.
* HP-8 s produced sold Hi-Tek Polymers.
i and by
* Guar available
5200 is through
Economy
Mud Products.
The polyacrylamide the polyacrylate
(PL1400s), (FP100e),
5p CMDHPC, and CM- Starch showed benefits
CNgiPC, throughout
the
17
WO 94/03648 ~ ~~~ ~'~ PCT/US92/06551,
addition of caustic. This was not the case with the CM-Guar.
Small additions of caustic significantly improved performance,
however when the dosage of caustic increased
was beyond
optimum levels, both the wet and dry trengths weredestroyed.
s
w
Example 5
Non-ionic polymers have also beenconsidered
for use a
binders: These pollrmers incl ude, but are not limited
to
hydroxyethyl cellulose (HEC), methyl
hydroxyethyl
cellulose
(Meth. HEC), hydroxypropyl ce llulose HPC), starch,dextrin,
(
guar (guar 5200), and hydroxypropyl' stic
guar (HPG). Cau
addition to these binders was also investigated, the data
and
is tabulated in Table 5, below.
,15 TABLE 5
Polymer Add'n NaOH Moi ture Drop # Dry Crush
#/LTDC #/LTDC (lbs)
HEC / T.0 96 7.7 2.9
HEC 1.0' .24 9.9 11.1 3.4
HEC 1.0 1.2 10,1 10.7 3.6
Meth.HEC 1.0 g7 5:9 4:3
Meth.HEC 1.0 .24 9.9 7.0 4:6
25,
4 HPC 1.0 9:9 6.1 2E
HPC 1.0 .24 10:9 6.7 3.0
Starch 4:0 9.8 4.1 5.8
3 0 Starch 40 .24. 101 4.7 5.7
Dextrin 4.0 8.5 2.5 4:9
Dextrin 4.0 :24 g2 2.8 4.8
35 Guar 5200 1.0 10.7 4:6 1.8
Guar 5200 1.0 .24' 9:7 3.8 1.4
HPG (IiP8 ) 1. 0 --_- 113 7 . 7 2 , p
HPG (HP8) 1:0 .24 95 2:7 ' 1,5
The data clearly demonstrate that the cellulos3cs
all showed
some improvement, albeit the improvements as great as
were,not
.fir
~~ 4:5 those seen with anionic binders:
WO 94/03648 PCT/US92/06551
The starch and dextrin binders tested showed no
improvement in wet drop numbers and dry strengths.
Example 6
To determine whether or not caustic itself may be
contributing to the dry strength of pellets by forming its own
binder bridges, iron ore was pelletized using only caustic.
The data is compiled in Table 6 below.
TABLE 6
NaOH Add'n Moisture Drop # Dry Crush (lbs)
____ 8.9 2.3 '8
.4#/LTDC 9.2 2.6 1.6
The data show that NaOH provides some, but minimal binding
action when employed alone.
Example 7
All previous testing employed only NaOH as a source of
OH' ions. The present example investigates the use of other
metal hydroxides for synergistic effect. The results are
tabulated in Table 7.
TABLE 7
Peridur 30~ Hydroxide Add'N Moisture Drop # Dry'
Crush
#/LTDC Source #/LTDC
(lbs)
1.0 KOH .45 10.0 5.4 2.8
1.0 NH,OH 1.46 10.0 6.4 3.3
1.0 Mg(OH)2 :45 9.9 4.3 1.9
1.0 ___ ___ 10.0 5.0 1.8
With the potassium hydroxide (KOH) and the ammonium hydroxide,
(NHaOH) improvements, most noticeably in;the dry crush, were
seen. This was not the case with the magnesium hydroxide
Mg(OH)2, which appeared to deteriorate the surface~conditions
40 on the pellet, turning the green ball rough and wet.
19
WO 94/03648 ~ ~~ ~ ~ PCT/US92/06551
The results seen with the magnesium hydroxide'were not
unexpected. It is known that any divalent canon will react
with the CMC and cause a decrease in viscosity and/or
,performance. The NH4+ and K+ ions resulting from the other two
hydroxides are monovalent cations and cause no adverse '
.M
effects.
While NaOH appears to outperform the other metal
hydroxides, both KOH and NFi,OH seem to exhibit some synergism
to the binding mechanism.
EXAMPLE g
All previous examples employed only iron cre from a
taconite source from northern Minnesota: Several other types
of ore bodies'abound; most notably the specular.hematites in
eastern Canada and'the magnetite ores i:n Sweden. Tests were
run employing-a specular hematite ore from IOC and a magnetite
ore from LKAB~ The results are tabulated in Table',8, below.
TABLE g
ORE Peridur 300 NaOH Moisture Drop # ' Dry Crush
#/LTDC #/LTDC
25' IOC 1.0 ___ g,8 g., 2.7
IOC 1.0'' .24 9.0 9.4 ' 4.0
LKAB 1.2 9:4' 5.0 ~ 4.8
.30 I~CAB 1.2'.24 9.5 7:2 ', 7.1
The data clearly show that other ore sources demonstrate the
°3~5 same type'of synergism exhibited by the taconite are source.
The foregoing data clearly demonstrate the synergistic
results of the present binder composition, which supports the
patentability of the present invention.
Y~40'
WO 94/03648 PCT/US92/06551
. ~ ~ ~~
The foregoing examples have been presented to demonstrate
the surprising and unexpected superiority of the present
invention in view of known technology, and said examples are
.not intended to restrict the spirit and scope of the following
claims.
15
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