Process for agglomerating particulate material

The present invention generally relates to a process of agglomerating particulate material in the presence of water which comprises mixing said particulate matreial with a binding effective amount of at least one water soluble polymer, and a binder enhancing effective amount of caustic, to produce a mixture, and forming said mixture into agglomerates.

BACKGROUND OF THE INVENTION 
The present invention relates to a novel binder composition for 
agglomerating particulate materials, a novel process for agglomerating 
particulate materials using 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 is commercially used in industries where materials are 
encountered in a form which is too finely divided for convenient 
processing or handling. Thus, there is a need to upgrade the size, density 
and/or uniformity of finely divided particles for more efficient handling, 
processing or recovery. Agglomeration is particularly useful in the metal 
refining industry, where the concentrate ore 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 agglomerate or pelletize finely 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 art as "concentrate". 
After screening, a binding agent is added to the wetted mineral ore 
concentrate and the binder/mineral ore composite is conveyed to a balling 
drum or other means for pelletizing the ore. The binding agent serves to 
hold or bind the mineral ore together until after firing. After the 
balling drum operation, the pellets are formed, but they are still wet. 
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.degree. 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.degree. 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 alkalis 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, 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. Pat. 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, 
0.001-10% by weight of a water soluble surfactant and 0-15 weight % of 
Borax. 
U.S. Pat. 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. Pat. No. 4,288,245 discloses pelletization of metallic ores, 
especially iron ore, with carboxymethyl cellulose and the salt of a weak 
acid. 
U.S. Pat. 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 of 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 synthetic. The 
mixture may optionally comprise a pelletizing aid 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. 
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 material with a binding effective amount of at least one water 
soluble polymer, and a binder enhancing effective amount of caustic to 
produce a mixture, and forming said mixture into agglomerates. 
In another embodiment, the present invention 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.

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 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 term "agglomerated" or "agglomeration" as used in the context of the 
present invention shall mean the processing of finely divided materials, 
whether in powder, dust, chip, or other particulate form, to form 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, chrome, copper, nickel, zinc, lead, uranium, borium and the like. 
Mixtures of the above materials or any other metal occurring in the free 
or molecularly combined material state as a mineral, or any combination of 
the above, or other metals, or metal containing ores capable of 
pelletization, may 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 or recovered from various processes. 
Iron ore or any of a wide variety of the following minerals may form 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 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 oxide; 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 polymer(s) 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, 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 carboxymethyl cellulose having a Brookfield viscosity 
in a 1% aqueous solution of more than about 4,000 cps at 30 rpm, spindle 
#4. 
A series of commercially available binders containing sodium carboxymethyl 
cellulose especially useful in the present invention is marketed by the 
Dreeland, Inc. of Virginia, Minn., Denver, Colo., and Akzo Chemicals of 
Amersfoort, the Netherlands, under the trademark Peridur.RTM.. 
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 particulate material to be agglomerated or 
pelletized, the moisture content of the particulate material, particle 
size, the agglomeration equipment utilized, and the desired 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.sup.-) 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 limitation, a binding effective amount of 
caustic will typically be in the range of between about 0.004% to 0.15% by 
weight based on the dry mixture of particulate material, polymer and 
caustic. Preferably, caustic is present in the range of between about 
0.01% to 0.04% by weight, and most preferred at about 0.03% 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 0.004% 
to 0.15% by weight of sodium hydroxide to produce a mixture, and forming 
said mixture into agglomerates. 
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 0.04% 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 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 10% to 40% 
by weight of sodium hydroxide. 
In yet another embodiment, the present invention contemplates a binder 
composition which comprises 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% by weight of a salt of a 
weak acid, such as sodium citrate and or soda ash. 
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. Pat. Nos. 4,288,245 and 4,597,797 such 
as sodium citrate, soda ash, and the like. 
The ratios of 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 the desired properties of the agglomerates 
to be prepared. A person of ordinary skill in the art can readily 
determine the specific amounts that will be most suitable for individual 
circumstances. Pelletization is generally carried out using the binder 
composition 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. 
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, liquid 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 and 
adequately hydrated prior to being formed 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. 
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.degree. F., 
preferably to at least about 2400.degree. 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.degree. F., more 
preferably at about 2400.degree. 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 suitable for non-ferrous 
concentrated ores such as ores of zinc, lead, tin, nickel and chromium and 
oxidic materials such as silicates and quartz, and sulphidic materials. As 
a practical matter, this invention is intended for use 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 an average diameter of about 1/4 to about 1 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 can be prepared. 
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 examples 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. 
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. 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 Drop Number was determined by repeatedly dropping two groups of ten 
(10) 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 required to 
produce a crack on the surface of each pellet was recorded. The average of 
all 20 pellets was taken to determine the drop number of each agglomerated 
mixture. 
Dry 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 Chatilion Spring Compression Tester, 
Model LTCM (25 pound range) at a loading rate of 0.1 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.sup.-, as binding agents for particulate material, which is iron ore 
unless otherwise specified. 
EXAMPLE 1 
In this example, a pure sodium carboxymethyl cellulose (CMC) polymer binder 
was employed (Peridur.RTM.300Z)with and without the addition of caustic. 
Table 1, below clearly shows that the performance of the pure CMC binder 
is tremendously improved by the addition of caustic. 
TABLE 1 
______________________________________ 
PURE CMC NaOH Dry Crush 
#/LTDC #/LTDC Moisture Wet Drop 
(Lbs) 
______________________________________ 
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 1 clearly show that the performance of pure CMC is 
greatly enhanced by the addition of NaOH. In this case, there is an 
optimum level of NaOH addition at between about 0.24 to 1.2 #/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 CMC containing up to about 25% salt byproducts (Peridur 
200.RTM.)was also tested with and without the addition of caustic. Table 
2, below, contains the data. 
TABLE 2 
______________________________________ 
Technical 
Grade CMC 
NaOH Dry Crush 
#/LTDC #/LTDC Moisture Wet Drop 
(Lbs) 
______________________________________ 
.90 -- 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 
______________________________________ 
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. 
EXAMPLE 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 
Crush Add'n NaOH 
(lbs) #/LTDC #/LTDC Moisture 
Drop # Dry 
______________________________________ 
Peridur .RTM. 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 
Peridur .RTM. 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 9.7 6.4 7.2 
Peridur .RTM. 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 
______________________________________ 
*Peridur .RTM. 2.15, Peridur .RTM. 3.15 and Peridur .RTM. 3.30 are binder 
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. 
EXAMPLE 4 
In this trial, applicants tested a series of anionic polymers, including 
polymers of polyacrylamide (PL1400.RTM.); POLYACRYLATE (FP 100.RTM.), CM 
GUAR carboxymethyldihydroxypropyl cellulose (CMDHPC), 
carboxymethylhydroxyethyl cellulose (CMHEC), and, Stabilose.RTM. LV, a 
carboxymethyl starch (CM Starch) with and without caustic addition. The 
data is tabulated in Table 4 below. 
TABLE 3 
______________________________________ 
Product 
Crush Add'n NaOH 
(lbs) #/LTDC #/LTDC Moisture 
Drop # Dry 
______________________________________ 
PAM (PL 1400) .RTM. 
1.1 -- 10.8 5.5 1.6 
PAM (PL 1400) 
1.1 .24 11.3 6.9 1.9 
PAM (PL 1400) 
1.1 1.2 11.0 7.2 3.4 
PAA (FP 100 .RTM. ) 
1.0 -- 9.1 2.9 2.5 
PAA (FP 100) 
1.0 1.2 9.3 2.9 5.3 
CM-GUAR 1.0 -- 10.0 7.0 1.7 
CM-GUAR 1.0 .12 10.2 8.8 2.3 
CM-GUAR 1.0 .24 10.1 6.9 2.7 
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 
CMHEC 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 .RTM. is a polyacrylamide commercially available from Stockhausen 
Inc. 
*FP100 .RTM. is a polyacrylate commercially available from Polyacryl Inc. 
*HP8 is produced and sold by HiTek Polymers. 
*Guar 5200 is available through Economy Mud Products. 
The polyacrylamide (PL140.RTM.), the polyacrylate (FP100.RTM.), CMDHPC, 
CMHPC, and CM- Starch showed benefits throughout the 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 was 
increased beyond optimum levels, both the wet and dry strengths were 
destroyed. 
EXAMPLE 5 
Non-ionic polymers have also been considered for use a binders. These 
polymers include, but are not limited to hydroxyethyl cellulose (HEC), 
methyl hydroxyethyl cellulose (Meth. HEC), hydroxypropyl cellulose (HPC), 
starch, dextrin, guar (guar 5200), and hydroxypropyl guar (HPG). Caustic 
addition to these binders was also investigated and the data is tabulated 
in Table 5, below. 
TABLE 5 
______________________________________ 
Add'n NaOH Dry Crush 
Polymer #/LTDC #/LTDC Moisture 
Drop # 
(lbs) 
______________________________________ 
HEC 1.0 -- 9.6 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 -- 9.7 5.9 4.3 
Meth.HEC 
1.0 .24 9.9 7.0 4.6 
HPC 1.0 -- 9.9 6.1 2.6 
HPC 1.0 .24 10.9 6.7 3.0 
Starch 4.0 -- 9.8 4.1 5.8 
Starch 4.0 .24 10.1 4.7 5.7 
Dextrin 4.0 -- 8.5 2.5 4.9 
Dextrin 4.0 .24 9.2 2.8 4.8 
Guar 5200 
1.0 -- 10.7 4.6 1.8 
Guar 5200 
1.0 .24 9.7 3.8 1.4 
HPG (HP8) 
1.0 -- 11.3 7.7 2.0 
HPG (HP8) 
1.0 .24 9.5 2.7 1.5 
______________________________________ 
The data clearly demonstrate that the cellulosics all showed some 
improvement, albeit the improvements were not as great as those seen with 
anionic binders. 
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.sup.- ions. The 
present example investigates the use of other metal hydroxides for 
synergistic effect. The results are tabulated in Table 7. 
TABLE 7 
______________________________________ 
Peridur 300 .RTM. 
Crush 
#/LTDC Hydroxide Add'N 
(lbs) Source #/LTDC Moisture 
Drop # 
Dry 
______________________________________ 
1.0 KOH .45 10.0 5.4 2.8 
1.0 NH.sub.4 OH 
1.46 10.0 6.4 3.3 
1.0 Mg(OH).sub.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, (NH.sub.4 
OH) improvements, most noticeably in the dry crush, were seen. This was 
not the case with the magnesium hydroxide Mg(OH).sub.2, which appeared to 
deteriorate the surface conditions on the pellet, turning the green ball 
rough and wet. 
The results seen with the magnesium hydroxide were not unexpected. It is 
known that any divalent cation will react with the CMC and cause a 
decrease in viscosity and/or performance. The NH.sub.4 + and K+ ions 
resulting from the other two hydroxides are monovalent cations and cause 
no adverse effects. 
While NaOH appears to outperform the other metal hydroxides, both KOH and 
NH.sub.4 OH seem to exhibit some synergism to the binding mechanism. 
EXAMPLE 8 
All previous examples employed only iron ore 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 in 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 8 
______________________________________ 
Peridur 300 .RTM. 
NaOH 
ORE #/LTDC #/LTDC Moisture 
Drop # Dry Crush 
______________________________________ 
IOC 1.0 -- 8.8 8.1 2.7 
IOC 1.0 .24 9.0 9.4 4.0 
LKAB 1.2 -- 9.4 5.0 4.8 
LKAB 1.2 .24 9.5 7.2 7.1 
______________________________________ 
The data clearly show that other ore sources demonstrate the same type of 
synergism exhibited by the taconite ore source. 
The foregoing data clearly demonstrate the synergistic results of the 
present binder composition, which supports the patentability of the 
present invention. 
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.