EA040350B1 - COPOLYMER APPLICATION AND COMPOSITION INCLUDING THIS COPOLYMER FOR PELLETIZING METAL-CONTAINING ORE - Google Patents

Description

This invention relates to the use of a copolymer in combination with at least one pelletizing aid and an additional binder for pelletizing a metal-containing ore, as well as to a composition for pelletizing a metal-containing ore, comprising said copolymer and a pelletizing aid.

Background of the invention

The pelletizing process is an agglomeration without compression of the material in the form of pellets. A variety of materials can be subjected to such a process, including chemicals, metal-bearing ores such as iron ores, animal feed, and the like.

For example, iron ore pellets are spheres typically 8 to 18 mm in size, which are used as feedstock for blast furnaces. They typically contain at least 60 to 70% iron and various additional materials to control the chemical composition and metallurgical properties of the pellets.

In the direct reduction process, pellets having high uniform mechanical strength and high abrasion strength increase the production of sponge iron using the same amount of fuel. Iron ore pellets may also be less vulnerable to breakage during transport due to higher abrasion resistance. In addition, pellets facilitate processing.

The pelletizing process combines mixing of raw materials, pelletizing and heat treatment in which a soft raw ball is baked into a hard sphere. The raw material is rolled into a ball and then fired in a particle sintering furnace into a hard sphere. The packed sphere configuration of the metal-containing ore pellets allows air to flow between the pellets while reducing the resistance to air that flows through the layers of material during smelting. In contrast, the configuration of the metal-containing ore powder (instead of the metal-containing ore pellets) in the blast furnace is more densely packed and obstructs airflow, plugging the furnace.

Additional materials that may be added to pelletize a metal-bearing ore, such as an Fe-bearing ore, may include basicity control additives. Examples of additional materials include limestone and/or dolomite and solid fuel additives such as coal/coke breeze. In addition, a binder may be added. In many cases, bentonite, an absorbent aluminum phyllosilicate, is used as the binder because its use typically provides pellets with desirable mechanical properties, such as wet strength, dry strength, and falls. Bentonite swells on contact with water and forms a viscous, sticky mass that is used as an active binder. However, bentonite does not burn out during the firing process, and thus bentonite or other silicon-based derivatives thereof formed during sintering remain, which is undesirable.

Other binders, such as Alcotac® FE13 organic binder (BASF SE) containing acrylamide-acrylic acid copolymer or cellulose-based binders, are also known to be suitable for pelletizing metal-bearing ore. The advantage of organic binders is that they are combusted during sintering and thus the remaining metal pellets do not contain residual organic binder. However, known organic binders by themselves generally do not provide the same desirable mechanical properties for metal-containing pellets as compared to bentonite. Thus, compositions containing bentonite along with other binders are often used as a binder.

Patent application WO 2013/010629 (A1) describes binder compositions for pelletizing fine mineral particles, including:

a) at least one colloidal agent that exerts a cohesive force on the mineral particles forming pellets, and

b) at least one synthetic polymer which uniformly disperses the mineral particles in the pellets.

US 4,684,549 discloses a process in which iron ore pellets are produced by adding a binder containing an organic polymer or a copolymer of sodium acrylate and acrylamide.

US Pat. No. 4,728,537 describes organic polymeric binders such as cationic polymers of diallyldimethylammonium chloride and quaternized dialkylaminoalkyl(methyl)acrylates and quaternized dialkylaminoalkyl(methyl)acrylamides.

US 4,767,449 relates to an agglomeration process comprising a two-component binder system, the first component of which is a binder polymer and the second component is a clay. The polymer or copolymers are derived from monomer units of acrylamide, sodium acrylate, vinyl acetate and poly(ethylene oxide). The polymer may also be a polysaccharide, such as carboxymethyl cellulose, guar gum and hydroxyethyl cellulose.

US 5,294,250 discloses a clay-free self-fluxing binder composition containing as an additive a carrier selected from the group of synthetic or natural magnesium and/or calcium minerals such as calcite, olivine, magnesite and dolomite, and one organic enhancer consisting of a high viscosity natural polysaccharide such as guar gum.

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In general, there is still a need to reduce the amount of bentonite in metal-containing ore pellets while maintaining at least the required mechanical properties of the metal-containing pellets.

There is also still a need to develop alternative organic binders for pelletizing metal-containing ores in order to obtain metal-containing ore pellets with desired mechanical properties.

Thus, it is an object of the present invention to provide metal-containing ore pellets that provide the desired mechanical properties using organic binders.

Brief summary of the invention

This object has been achieved by using the copolymer in combination with at least one pelletizing aid and an additional metal ore pelletizing binder as defined below in the detailed description section.

In addition, the problem was solved by using the composition according to the invention for pelletizing a metal-containing ore, comprising the above copolymer and a pelletizing aid, as defined below in the detailed description section.

Detailed description

This invention relates to the use of a copolymer in combination with at least one pelletizing aid and an additional binder for pelletizing a metal-containing ore, wherein the copolymer contains monomeric units derived from

i) at least one anionic, monoethylenically unsaturated hydrophilic monomer A;

ii) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer B and iii) at least one monomer C of formula (I)

H ₂ C=C (R ¹ ) -R ² -0 (-CH2-CH2-O-) _k -CH ₂ -CH ₂ -R ³ (I) where R ¹ means hydrogen or methyl;

R ² means -OR ⁴ where R ⁴ means -(CH ₂ ) _p - where n means an integer from 1 to 6;

R ³ means hydrogen or OH and k means a number from 0 to 300, and where the additional binder is an absorbent aluminum phyllosilicate, and where the pelletizing aid is a water-soluble material selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium silicate , sodium phosphate, sodium stearate, sodium benzoate, sodium tartrate, sodium oxalate, sodium citrate, sodium acetate, the corresponding ammonium, potassium, calcium and magnesium salts of the above sodium, urea and calcium oxide salts.

Monomer C is a hydrophilic monomer that can interact with other hydrophilic interaction partners. Surprisingly, it has been found that when a copolymer of the invention containing monomer units derived from at least one monomer C is used as a binder in the pelletization of a metal-containing ore, the pellets are superior, for example, more stable, as shown, for example, by an increase in the number of drops, compared to using other modern binder polymers for pelletizing metal-containing ore.

Preferably R ¹ is hydrogen.

In another preferred embodiment, R ³ means -OH.

In another preferred embodiment, n is a number from 2 to 5.

In a particularly preferred embodiment, n is 4.

Preferably, the additional binder is bentonite.

In a preferred embodiment, the invention relates to the above application, where the copolymer is water-soluble.

In one embodiment, k is a number between 1 and 300.

In another preferred embodiment, k is a number from 5 to 150. In a more preferred embodiment, k is a number from 5 to 50. Even more preferably, when k is a number from 11 to 50.

In a particularly preferred embodiment of the invention, k is a number from 5 to 75.

In another preferred embodiment, monomer C has a weight average molecular weight (MW) of about 500 to about 12,000 g/mol. It is preferred that the MW of monomer C is from about 500 to about 6000 g/mol, more preferably from about 500 to about 4000 g/mol, and even more preferably from about 500 to about 3000 g/mol. The MW of monomer C can be determined using gel permeation chromatography (GPC). Those skilled in the art will know how to determine the molecular weight of a copolymer using GPC.

In yet another preferred embodiment, monomer C is vinyloxybutyl polyethylene glycol. The preparation of vinyloxybutyl polyethylene glycol is described, for example, in WO 2014/095608 A2, page 32, example M1. Thus, vinyloxybutyl polyethylene glycol can be obtained by reacting hydroxybutyl vinyl ether with ethylene oxide.

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In a preferred embodiment, vinyloxybutyl polyethylene glycol is prepared using a molar ratio of ethylene oxide to hydroxybutyl vinyl ether from 10:1 to

70:1.

In another preferred embodiment, vinyloxybutyl polyethylene glycol is prepared using a molar ratio of ethylene oxide to hydroxybutyl vinyl ether from 10:1 to 50:1 for the reaction.

In another preferred embodiment, vinyloxybutyl polyethylene glycol is prepared using a molar ratio of ethylene oxide to hydroxybutyl vinyl ether from 15:1 to 35:1 for the reaction.

In yet another preferred embodiment, vinyloxybutyl polyethylene glycol is prepared using a molar ratio of ethylene oxide to hydroxybutyl vinyl ether from 22:1 to 23:1 for the reaction. This preferred monomer C is hereinafter referred to as VOBPEG 1100.

For VOBPEG 500, the molar ratio of ethylene oxide to hydroxybutyl vinyl ether is about 11:1 in the reaction. For VOBPEG 3000, the molar ratio of ethylene oxide to hydroxybutyl vinyl ether is about 68:1 in the reaction. For VOBPEG 5800, the molar ratio of ethylene oxide to hydroxybutyl vinyl ether is from about 130:1 to about 134:1 in the reaction.

In one embodiment, monomer C is selected from VOBPEG 500, VOBPEG 1100 and VOBPEG 3000.

In a preferred embodiment, monomer C is VOBPEG 500 or VOBPEG 3000.

In a preferred embodiment, monomer C is a vinyloxybutyl polyethylene glycol with a molecular weight, preferably average molecular weight (MW), of about 100 to 10000 g/mol, preferably about 250 to about 4000 g/mol, more preferably about 500 to 2000 g /mol. An MW of 1100 g/mol or less is particularly preferred. In a preferred embodiment, at least one monomer C is vinyloxybutyl polyethylene glycol, where k is preferably a number from 5 to 75.

In a preferred embodiment, the copolymer contains from 0.1 to 15 wt.% and preferably from 0.5 to 4 wt.%, at least one monomer C of formula (I). It is particularly preferred that the copolymer contains from about 0.5 to about 3 wt. % of monomer C, and more preferably from about 2 to about 3 wt.

Ideally, the copolymers used in accordance with the invention should be miscible with water in any ratio. However, according to the invention, it is sufficient that the copolymers are dissolved in water at least at the concentration desired for use and at the desired pH. Typically, the solubility of the copolymer in water at room temperature under conditions of use should be at least about 10 g/L, or at least about 25 g/L. In a preferred embodiment, the molecular weight of the copolymer is at least 300,000 Da, preferably at least 500,000 Da, and even more preferably at least 1,000,000 Da. Those skilled in the art know how to determine the molecular weight of a copolymer, which is usually defined as an average, preferably as a weight average molecular weight (MW) or as a number average molecular weight (M _n ). The molecular weight of the copolymer can be determined, for example, using permeation chromatography, which is particularly suitable for determining the molecular weight for copolymers having a molecular weight of up to about 1 MDa.

In a preferred embodiment of the invention, the amount of copolymer used in the homogeneous metal-containing ore pelletizing mixture is typically from about 0.005 to about 0.1% by weight, and preferably from about 0.01 to about 0.1% by weight, based on the weight of the homogeneous mixture containing ore, copolymer and moisture. The amount of moisture will vary depending on the ore and the process, but is typically in the range of about 7 to about 15% by weight, or about 8 to about 12% by weight, based on the weight of the homogeneous mixture. Some or all of this moisture may be introduced along with the binder copolymer and/or optional processing polymer or by deliberate addition of water, but often all moisture is already present in the ore and all additives such as copolymer are added dry.

In yet another preferred embodiment, the metal ore pelletizing copolymer is used in combination with an additional binder, which is bentonite. Without being limited by theory, it is believed that the use of the copolymer of the present invention in combination with an aluminum phyllosilicate absorbent, preferably bentonite, can be particularly advantageous because the polyethylene glycol (PEG) chains can be modified or reacted with the aluminum phyllosilicate absorbent, preferably bentonite, and thereby its ability to function as a binder for pelletizing metal-containing ore is improved. PEG chains can also directly interact with iron ore and act as a binder.

In another preferred embodiment, the copolymer according to the invention is mixed with aluminum phyllosilicate absorbent, preferably bentonite, in a weight ratio of 10 to 50 parts of aluminum phyllosilicate absorbent, preferably bentonite, to 1 part of copolymer.

In another preferred embodiment, the copolymer according to the invention is mixed with aluminum phyllosilicate absorbent, preferably bentonite, in a weight ratio of 10 to 30 parts of aluminum phyllosilicate absorbent, preferably bentonite, to 1 part of copolymer.

In a preferred embodiment, at least one monomer A contains at least one functional group selected from the group that includes -COOH, -SO3H, -PO3H2, their salts, and mixtures of any of the above.

Examples of monomer A containing -COOH groups include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, or fumaric acid. In one embodiment, monomer A containing -COOH groups includes crotonic acid, itaconic acid, maleic acid, or fumaric acid.

Examples of monomers A containing sulfonic acid groups include vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, or 2-acrylamido-2, 4,4-trimethylpentanesulfonic acid. Preference is given to vinylsulfonic acid, allylsulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid.

In a preferred embodiment of the invention, at least one monomer A is 2-acrylamido-2-methylpropanesulfonic acid (AMPS or ATBS).

In a preferred embodiment, the invention relates to the above use, where at least one monomer a contains at least one functional group selected from the group that includes -COOH, -SO3H, -PO ₃ H ₂ , their salts and mixtures of any of the above, where more preferably at least one monomer A is 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or a salt thereof.

Examples of A monomers containing phosphonic acid groups include vinylphosphonic acid, allylphosphonic acid, N-acrylamidoalkylphosphonic acids, N-methacrylamidoalkylphosphonic acids, acryloyloxyalkylphosphonic acids, methacryloyloxyalkylphosphonic acids, with vinylphosphonic acid being preferred.

In a preferred embodiment, the monoethylenically unsaturated, hydrophilic monomer B is selected from the group consisting of acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N,N'-dimethylacrylamide, N,N'-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, uncharged vinylamides such as vinylformamide or N-vinylpyrrolidone, or mixtures thereof. Preference is given to acrylamide or methacrylamide, especially acrylamide. Preferably, when a mixture of different monomers B is used, at least 50 mole % of monomer B should be acrylamide or methacrylamide, and acrylamide is more preferred.

In another preferred embodiment, the copolymer of the invention does not contain a COOH or COO- moiety as a side chain, and thus the copolymer of the invention does not originate from monomers such as acrylic acid and/or methacrylic acid.

In yet another preferred embodiment, the copolymer of this invention does not contain a hydrophobic radical as a side chain, such as a hydrocarbyl radical containing two or more carbon atoms, including cyclic and aromatic hydrocarbon groups. Acrylic acid alkyl esters are also included in the scope of the hydrophobic radical as a side chain.

In another preferred embodiment, the copolymer according to this invention does not contain an alkyl ester of acrylic acid.

In one embodiment, the copolymer of this invention does not contain at least one anionic, monoethylenically unsaturated, hydrophilic monomer A and/or at least one uncharged, monoethylenically unsaturated, hydrophilic monomer B. In this context, it should be understood that the presence of monomer C does not automatically mean that monomer A and/or monomer B must be present in the copolymer according to the invention.

Of course, the monomers can also be salts of anionic acidic monomers. Suitable counterions include, in particular, alkali metal ions such as Li ⁺ , Na ⁺ or K ⁺ and ammonium ions such as NH ₄ ⁺ or ammonium ions with organic radicals.

Preferably, in a copolymer containing monomer units derived from monomers A and B, monomer A and B are miscible with water in any ratio, but for the implementation of the invention it is sufficient that the copolymer according to the invention has the solubility in water mentioned at the beginning. Preferably, the solubility of monomers A and B in water at room temperature should be at least 50 g/l, preferably at least 150 g/l and more preferably

- 4 040350 at least 250 g/l.

In a preferred embodiment of the invention, monomer A is AMPS and/or monomer B is acrylamide.

In yet another preferred embodiment, the copolymer contains about 2% by weight of at least one monomer C, about 48% by weight of at least one monomer A, and about 50% by weight of at least one monomer B, where monomer A is preferably AMPS and/or monomer B is preferably acrylamide. The weight content in each case is given in terms of the total weight of the monomers in the copolymer.

In one embodiment, the copolymer used in accordance with this invention was obtained by polymerization of a mixture of monomers in the presence of at least one branching agent. The branching agent may cause covalent or ionic cross-linking through pendant groups (for example, by using a glycidyl ether or a polyvalent metal salt), but preferably the branching agent is a diethylenically unsaturated, monomeric branching agent. The amount of branching agent is preferably in the range of from about 2 to about 200 ppm, and more preferably from about 10 to about 100 ppm. The ppm values are based on the total weight of the copolymer.

In a preferred embodiment, at least one branching agent is selected from methylenebis-acrylamide (MBA) and tetraallylmonium chloride (TAAX) or a combination thereof.

In a preferred embodiment, the invention relates to the above application, where the metal-bearing ores are selected from the group of Fe-bearing ore, Cu-bearing ore, Mo-bearing ore, Ni-bearing ore, Cr-bearing ore or mixtures thereof, and Fe-bearing ore is preferred. In a particularly preferred embodiment, the Fe-containing ore contains magnetite, hematite or goethite, or combinations thereof.

This invention also relates to a composition for pelletizing a metal-containing ore, comprising

i) a copolymer, where the copolymer contains monomer units derived from:

a) at least one anionic, monoethylenically unsaturated hydrophilic monomer A;

b) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer B and

c) at least one monomer C of formula (I)

H ₂ C=C (R ¹ ) -R ² -0 (-CH2-CH2-O-) _k -CH ₂ -CH ₂ -R ³ (I) where R ¹ means hydrogen or methyl;

R ² means -OR ⁴ where R ⁴ means -(CH ₂ ) _p - where n means an integer from 1 to 6;

R ³ is hydrogen or OH and k is a number from 0 to 300, and ii) a pelletizing aid wherein the pelletizing aid is a water soluble material selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium silicate, sodium phosphate , sodium stearate, sodium benzoate, sodium tartrate, sodium oxalate, sodium citrate, sodium acetate, the corresponding ammonium, potassium, calcium and magnesium salts of the above sodium, urea and calcium oxide salts.

Preferably, the pelletizing aid ii) is sodium carbonate.

In a preferred embodiment, the invention relates to the above composition, wherein the composition further comprises an aluminum phyllosilicate absorbent, where preferably the aluminum phyllosilicate absorbent is bentonite.

In a preferred embodiment, R ³ is OH and/or k is a number from 1 to 300.

In a preferred embodiment, k is a number from 5 to 150, preferably from 5 to 75, more preferably from 5 to 50, and most preferably from 11 to 50.

In a preferred embodiment, at least one monomer C is vinyloxybutyl polyethylene glycol, where k is preferably a number from 5 to 75.

In a preferred embodiment, the copolymer indicated as i) contains from 0.1 to 15 wt.% and preferably from 0.5 to 4 wt.% of at least one monomer C of formula (I).

In a preferred embodiment, the copolymer designated as i) is water soluble.

In another preferred embodiment, the weight ratio of copolymer to auxiliary pelletizing agent is typically in the range of about 5:1 to about 1:5, and more preferably about 2:1 to about 1:2, by weight.

The ratio of copolymer to treatment polymer is typically in the range of from about 10:1 to about 1:2, and preferably from about 5:1 to about 1:1, by weight.

In another preferred embodiment, the water-soluble treatment polymer has a molecular weight ( _Mw ) of from about 1,000 to about 20,000. It is further preferred that the treatment polymer is a synthetic polymer obtained by polymerizing a water-soluble, ethylenically unsaturated, anionic monomer, or a mixture of water-soluble, ethylenically unsaturated monomers, containing at least 50 wt.% anionic monomer.

The treatment polymer typically consists of about 50 to about 100 wt.%, preferably about 75 to about 100 wt.%, even more preferably about 80 to about 100 wt. will form a water-soluble mixture with the anionic monomer. The non-ionic monomer may be a water-soluble monomer such as acrylamide, or it may be a potentially water-insoluble monomer such as an alkyl acrylate or methacrylate, such as methyl or butyl acrylate, provided that the insoluble monomer can be dissolved in the aqueous solution of the anionic monomer during polymerization and that the mixture provides a water-soluble polymer. The anionic monomer is typically an ethylenically unsaturated carboxylic monomer, usually in the form of an alkali metal (especially sodium) salt or other water-soluble salt, but if desired, some or all of the anionic monomer may be an ethylenically unsaturated sulfonic monomer such as AMPS or allylsulfonate or vinylsulfonate . Preferred carboxylic monomers are acrylic or methacrylic acid and most preferably the anionic monomer is sodium acrylate. Preferred treatment polymers are acrylic acid homopolymers (usually in the form of sodium polyacrylate).

The molecular weight of the treating polymer is preferably at least 2000 or 3000. It is often less than 10000 and preferably less than 8000, with values from 3000 to 6000 being preferred, the molecular weight being preferably the weight average molecular weight (MW). Molecular weight can be measured by gel permeation chromatography, preferably measured by size exclusion chromatography using Toac Haes TSK PWXL columns (G6000+G3000+protection) or other suitable columns, for example using dipotassium hydrogen orthophosphate trihydrate as eluent and several sodium polyacrylate standards in range 782200-1250 g/mol and sodium acrylate monomers as an additional standard. Molecular weights can be measured as for the all sodium salt.

Preferred processing polymers also have narrow molecular weight distributions in addition to certain very low molecular weights.

Higher molecular weights in the range of 1,000 to 20,000 are sometimes more suitable for treatment polymers when, as is sometimes preferred, the treatment polymer should be administered in the form of granules. When the treatment polymer is to be supplied in liquid form, the treatment polymer is usually prepared by solution polymerization in the usual manner. When the polymer to be treated is supplied in the form of a powder, the polymer is usually produced by reverse phase bead polymerization or by spray drying of a polymer solution.

If the treatment polymer is in particulate form, it typically has a particle size of at least 90% by weight less than 300 microns and more preferably less than 200 microns and often less than 100 microns. Typically, the particle size is at least 90 wt.% greater than 10 μm. For example, the particle size can be determined by sieving or laser granulometry.

It is understood that the water-soluble polymers for processing used in the invention are materials that are known in the industry as dispersing agents. It is possible to obtain improved dry strength by including a treatment polymer in the composition according to the invention. Furthermore, this can advantageously be achieved when the total amount of binder system substances (copolymer, processing polymer and/or pelletizing aid) remains constant in the composition according to the invention.

The amount of treating polymer to be added to the composition according to the invention will vary depending on the nature of the ore and the remaining materials of the binder system, but is often at least 0.005% by weight and most preferably at least 0.008% by weight. It is often in the range of about 0.01 to about 0.05% by weight. Amounts above 0.1 wt.% are usually not needed, but can be used if desired. Wt.% are given in terms of the total weight of the specified mixture containing metal-containing ore, copolymer and moisture.

The treatment polymer may be incorporated into the homogeneous mixture of ore, binder polymer and moisture by addition at any suitable stage. It is often desirable to thoroughly mix the treatment polymer with the ore and some or all of the moisture prior to adding the binder polymer or other components of the binder system. For example, the treating polymer may be added as a liquid or powder before the filters, which typically precede the addition of the binder prior to drum or disk pelletization.

In one embodiment, the treatment polymer and copolymer are typically added separately, ie from separate sources, either simultaneously or sequentially in any order. This facilitates the addition of treatment polymers and copolymers in various physical forms, such as solution treatment polymer and powder binder polymer. In particular, the treatment polymer can be added as a solution before the filters, and

- 6 040350 copolymer - in powder form after filters, but before pelletizing.

While it is often convenient to add the treating polymer as a solution, it is generally preferred to add it as a powder. The powder particles can be added separately from the copolymer (often at the same time as the binder polymer), but often the treatment polymer particles can be added as a mixture with the copolymer particles.

Instead of adding the treating polymer as a solution or mixture of particles with copolymer particles, some of the treating polymers can be added as a binder to binder polymer particle aggregates as in EP 376713. However, these aggregates need to be disintegrable as described in EP 376713, and it is generally impractical to obtain disintegrable aggregates containing both the copolymer and all of the desired polymer to be processed. Accordingly, if the copolymer is to be administered in the form of aggregates, it is generally preferred that they do not include the treatment polymer as a binder and it is generally preferred that they do not contain any treatment polymer or, if present, the amount of treatment polymer in the aggregates should be not more than 50 wt.% and, as a rule, not more than 10 wt.% of the total amount of processing polymer used in the invention.

If desired, the composition according to the invention may further comprise an absorbent aluminum phyllosilicate, preferably bentonite, as an additional binder.

In another preferred embodiment, the copolymer according to the invention is mixed with aluminum phyllosilicate absorbent, preferably bentonite, in a weight ratio of 10 to 50 parts of aluminum phyllosilicate absorbent, preferably bentonite, to 1 part of copolymer.

In another preferred embodiment, the copolymer according to the invention is mixed with aluminum phyllosilicate absorbent, preferably bentonite, in a weight ratio of 10 to 30 parts of aluminum phyllosilicate absorbent, preferably bentonite, to 1 part of copolymer.

In one embodiment, the composition according to the invention contains from about 0 to about 60 wt.% auxiliary pelletizing agent, from about 0 to about 50 wt.% polymer for processing and at least 30 wt.% copolymer, and the total number of wt.% of the composition is 100 wt%. In a preferred embodiment, the auxiliary pelletizing agent is sodium carbonate and/or the processing polymer is a polyacrylate.

Within the scope of this invention, hydrophilic means that the respective solid hydrophilic particle has a water-to-air contact angle of <90°.

Methods for determining the contact angle are well known to those skilled in the art. For example, to determine the angle of contact with water, an optical analysis of the drop shape can be performed, for example, using a DSA 100 contact angle measuring device from Kruss (Hamburg, Germany) with appropriate software. Typically 5 to 10 independent measurements are taken to determine a reliable average contact angle.

As used herein, the term ore or metal-bearing ore refers to a naturally occurring substance that is a solid inorganic and is represented by a chemical formula that is usually abiogenic and may have an ordered atomic structure. Examples of metal ores include, but are not limited to, sulfides, oxides, halides, carbonates, sulfates and phosphates of valuable metals such as Ag, Au, Pt, Pd, Rh, Ru, Ir, Os, Cu, Mo, Ni, Cr, Mn, Zn, Pb, Te, Sn, Hg, Re, V, Fe, or mixtures thereof. The preferred metal-containing ores are Fe-containing ores. Examples of Fe-containing ores include, but are not limited to, magnetite, hematite, and goethite. In a preferred embodiment, the invention relates to the above composition, wherein the metal-bearing ore is selected from the group consisting of Fe-bearing ore, Cu-bearing ore, Mo-bearing ore, Ni-bearing ore, Cr-bearing ore, or mixtures thereof, and Fe- containing ore.

As used herein, the term monoethylenically unsaturated, as in a monoethylenically unsaturated monomer, refers to an organic compound that contains a -C=C- bond. Preferably, the monoethylenically unsaturated compound contains exactly one -C=C bond. In the context of a monoethylenically unsaturated monomer, it is meant that the monomer preferably contains a C=C- functional group for polymerization.

As used herein, the term diethylenically unsaturated, as in a diethylenically unsaturated monomeric branching agent, means that the compound contains two -C=C- bonds, which are preferably functional groups for polymerization, respectively.

The term anionic as used herein, as in an anionic monomer, refers to a negatively charged compound such as an anionic monomer. However, the term anionic monomer as used herein also refers to the corresponding salt containing the negatively charged anionic monomer and the corresponding free acid of the anionic monomer, ie the negatively charged anionic monomer bonded to hydrogen. Examples of anionic monomers, that

- 7 040350 thus include monomers containing at least one functional group selected from -COOH, -SO ₃ H, -PO3H2 or -COO-, -SO ₃ -, -PO ₃ H- or their salts. Other examples of anionic monomers include, but are not limited to, vinylsulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidobutanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, or 2-acrylamido-2 ,4,4-trimethylpentanesulfonic acid and their salts.

In a preferred embodiment, the invention relates to the above composition, where at least one monomer A of the copolymer contains at least one functional group from the group that contains -COOH, -SO3H, -PO3H2, their salts and mixtures of any of the above, where preferably at least At least one monomer A is 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or a salt thereof.

As used herein, uncharged, as in an uncharged monomer, refers to a compound that does not normally dissociate into anions and cations in significant amounts under standard conditions such as water at room temperature. In the context of uncharged monomers, this means that the monomers may contain appropriate functional groups such as amide groups. Thus, examples of uncharged monomers include, but are not limited to, acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N,N'-dimethylαcrylαamide, N,N'-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, or mixtures thereof. It is emphasized that free acids, for example a compound containing a -COOH, -SO ₃ H or -PO ₃ H ₂ group, are not considered as uncharged in accordance with this invention, but are considered as anionic. In a preferred embodiment, the invention relates to the above composition, wherein at least one monomer B is selected from the group consisting of acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N,N'-dimethylacrylamide, N,N'-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide , uncharged vinylamides or mixtures thereof, and where preferably at least one monomer B is acrylamide.

As used herein, the term synthetic polymer refers to a polymer that has been chemically synthesized, i.e., a man-made polymer. Typically, the term synthetic polymer includes thermoplastics, thermosets, elastomers, and synthetic fibers. The bases of common synthetic polymers such as polyethylene and polystyrene, polyacrylates are composed of carbon-carbon bonds, while heterochain polymers such as polyamides, polyesters, polyurethanes, polysulfides and polycarbonates contain other elements (for example, oxygen, sulfur, nitrogen) inserted along the main chain. Also, silicon forms similar materials without the need for carbon atoms, such as silicones bonded through siloxane bonds; these compounds are thus called inorganic polymers. Coordination polymers may contain a number of metals in the main chain with the presence of non-covalent bonds. The opposite of a synthetic polymer is a naturally occurring polymer such as cellulose.

As used herein, the term water-soluble polymer refers to polymers having polar or charged functional groups that render them soluble in water.

As used herein, the number of drops refers to the number of repeated drops of 9-16 mm wet pellets dropped onto a steel plate from a height of 45 cm without any cracking of the wet pellets. The number of drops measures the ability of wet pellets to maintain their shape during transfer operations.

The term wet strength as used herein is a measure of the load that a wet pellet can withstand, and this load is determined by applying pressure to the wet pellet until it collapses and the maximum load is fixed.

The term dry strength as used herein is a measure of how much stress a dry pellet can withstand. Typically wet pellets can be dried, for example for 3 hours at 110° C., and the dried pellet is broken and the maximum load recorded. Dry strength can be thought of as a measure of the ability of dried pellets to withstand processing during the roasting process.

Additional examples of aliphatic branched carbon radicals include cyclic hydrocarbons such as mono-, bi- or tricyclic saturated or unsaturated hydrocarbons containing from 6 to 30 carbon atoms. Examples include, but are not limited to, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclododecyl.

Examples of aromatic carbon radicals include, but are not limited to, aromatic carbocyclic rings with 6-30 ring members, including both mono-, bi-, and tricyclic ring systems. Non-limiting examples include -indenyl, -phenyl, -naphthyl, acenaphthyl-, anthranyl, phenanthryl, and the like.

As used herein, the term pelletizing aid refers to a compound that aids in pelletizing a metal-containing ore when used in conjunction with a copolymer in accordance with the present invention.

The auxiliary pelletizing agent is preferably a water soluble

- 8 040350 monomeric material. Examples of auxiliary pelletizers and suitable materials are described in EP 225171 and EP 288150, US 4767449 and US 4802914.

As used herein, the term hydrocarbon or carbon radical refers to an aliphatic and/or aromatic, linear or branched carbon radical. Thus, hydrocarbon radicals such as a hydrocarbon radical having 2 to 50 carbon atoms and the like refer to aliphatic and/or aromatic, linear or branched carbon radicals having 2 to 50 carbon atoms. For example, a hydrocarbon radical containing 2 carbon atoms is ethyl, a hydrocarbon radical containing 4 carbon atoms includes n-butyl, isobutyl and/or tert-butyl.

The term about in the context of this patent application, such as about 50% by weight, for example, means that the numerical value immediately after about may have slight deviations from the exact numerical value, for example, due to weighing errors, etc. In a preferred embodiment, the term about means a value within 15% (± 15%) of the value given immediately after the term about, including any numerical value in that range, up to a value equal to the upper limit (i.e. + 15%) and up to to a value equal to the lower limit (that is, -15%) of this range. For example, the phrase near 100 covers any number between 85 and 115, including 85 and 115 (except in the case near 100%, which always has an upper limit of 100%). In one aspect, about means ±10%, even more preferably ±5%, even more preferably ±1%, or less than ±1%. In another preferred embodiment, the term about, as in about 50% by weight, means 50% by weight ± 1% by weight or 50% by weight ± 0.5% by weight.

Example 1 Preparation of copolymers

100.0 g of distilled water is poured into a glass and then 149.56 g of sodium ATBS solution (50% solution in water), 140.82 g of acrylamide solution (50% in water) and 1.2 g of Trilon C solution (company BASF) (5% solution in water). Then 0.4 g of Xiameter AFE-0400 (antifoam) and 2.82 g of vinyloxybutyl polyethylene glycol (VOBPEG) 1100 were added and the pH was adjusted with sulfuric acid to pH 6.4. The rest of the water (without the water required for the initiators) was then added to give an active content of 37% and the solution was cooled to -3° C. and 2.4 g of V50 (Wako Chemicals) (10% solution in water) was added. The solution was then transferred to a thermos and degassed by purging with nitrogen for 30 min.

0.12 g of tert-butyl hydroperoxide (tBHP) (United Initiators) (1% solution in water) is added and after 1 min 0.24 g of sodium sulfite (1% solution in water) is added to initiate polymerization.

After reaching the maximum temperature (about 80°C), the thermos was placed in a heating cabinet at a temperature of 80°C for 2 hours. The gel was then granulated and dried for 2 hours at 55°C in a fluid bed dryer. Then the resulting polymer granules were crushed in a centrifuge mill.

Example 2 Pelletization of iron ore concentrate and analysis of pellets.

Magnetite ore having a moisture content of about 10% (9.3 to 9.7%) was mixed with the powdered binder premix using an Eirich model EL1 mixer for 3 minutes. The composition of the corresponding pellets is summarized in table. 1. The resulting homogeneous mixture was subjected to pelletizing using a 60 cm diameter inclined pelletizing disk rotating at 33 rpm. The resulting pellets had a size of 9.4 to 13.4 mm. Dry pellets were obtained after drying for 3 hours at 110°C. Wet and dry pellet strengths were measured using a Chatillon digital strength meter. A total of 25 pellets were compressed in the uniaxial direction, and the maximum compressive strength was recorded when the pellets were crushed. To determine the number of drops, wet pellets were repeatedly dropped onto a steel plate from a height of 45 cm and checked for visible cracks. The average number of falls until a crack was detected was counted as the number of falls.

The following binder compositions have been used to pelletize iron ore:

Alcotac® FE 14 (BASF SE) is a commercially available organic iron ore pelletizing binder containing a copolymer of acrylamide and acrylate monomers. In this example, Alcotac® FE14 was used as a preblend containing 65 wt% copolymer and 35 wt% sodium carbonate salt.

Composition 1 consisted of a copolymer based on the monomers of acrylamide (50 wt.%), Na-AMPS (48 wt.%) and vinyloxybutyl polyethylene glycol (VOBPEG) 1100 monomer (2 wt.%) and sodium carbonate. The composition contained 40 wt.% copolymer and 60 wt.% sodium carbonate salt. Composition 2 consisted of a copolymer based on monomers of acrylamide (48 wt.%, Na-AMPS (48 wt.%) and vinyloxybutyl polyethylene glycol (VOBPEG) 1100 monomer (4 wt.%) and sodium carbonate. The composition contained 40 wt.% copolymer and 60 wt.% sodium carbonate.

The composition of the binder and the average results are given in table. 1.

- 9 040350

Table 1. Composition and analysis results of iron ore pellets

Test Alcotac FE14 [wt. percent]* Composition 1 [wt. percent]* Composition 2 [wt. percent]* Humidity [percent] Dry strength [N] Number falls And for comparisons) 0.033 9.5 17 3.6 B (according to invented 0.033 9.4 19 4.0 shade) From (to invent- 0.033 9.6 20 4.7 niyu)

*weight. percent = weight percent based on the total weight of iron ore pellets.

Pellets containing compositions in accordance with this invention showed improved dry strength and a higher number of drops compared to pellets containing a commercially available polymer-based binder composition.

Example 3 Pelletization of an iron ore concentrate using bentonite in combination with an organic binder

In accordance with the same experimental pelletizing procedure as described in Example 2, binder compositions containing bentonite were tested together with the binder compositions of the present invention.

Binder compositions 3, 4 and 5 were used to pelletize iron ore in combination with bentonite and were compared with Alcotac® FE 14 (BASF SE) also used in combination with bentonite as a comparative example.

Alcotac® FE 14 (BASF SE) is a commercially available organic iron ore pelletizing binder containing a copolymer of acrylamide and acrylate monomers. In this example, Alcotac® FE14 was used as a preblend containing 65 wt% copolymer and 35 wt% sodium carbonate salt.

Composition 3 consisted of a copolymer based on monomers of acrylamide (68 wt.%), Na-acrylate (30 wt.%) and vinyloxybutyl polyethylene glycol (VOBPEG) 1100 monomer (2 wt.%) and sodium carbonate. The composition contained 40 wt.% copolymer and 60 wt.% sodium carbonate salt.

Composition 4 consisted of a copolymer based on monomers of acrylamide (67 wt.%), Na-acrylate (30 wt.%) and vinyloxybutyl polyethylene glycol monomer (VOBPEG) 1100 (3 wt.%) and sodium carbonate salt. The composition contained 40 wt.% copolymer and 60 wt.% sodium carbonate salt.

Composition 5 consisted of a copolymer based on monomers of acrylamide (66 wt.%), Na-acrylate (30 wt.%) and vinyloxybutyl polyethylene glycol (VOBPEG) 1100 monomer (4 wt.%) and sodium carbonate. The composition contained 40 wt.% copolymer and 60 wt.% sodium carbonate salt.

The composition of the binder and the average results are given in table. 2.

- 10 040350

Table 2. Composition and analysis results of iron ore pellets using bentonite or

bentonite yielded higher dry strengths and similar drop counts and wet strengths compared to those obtained with pellets made using bentonite in combination with a comparative copolymer.

Example 4 Further Experiments with Pelletization of Iron Ore Concentrate Using Bentonite in Combination with an Organic Binder.

Iron ore pellets are prepared in batches of 3000 g, in open aircraft tires, and a standard procedure is used for all tests. The iron ore and binder composition are pre-mixed in a bowl prior to agglomeration. Binder additive is calculated in terms of dry concentrate. The agglomeration device used is a 15x30 cm airplane tire for the production of green pellets. The resulting pellets had a size of 12.7 to 11.2 mm. Dry pellets were obtained after drying for 3 hours at 110°C. Wet and dry pellet strengths were measured using a Chatillon digital strength meter. A total of 25 pellets were subjected to compression in the uniaxial direction, and the maximum compressive strength was recorded when the pellets broke. To determine the number of drops, wet balls were repeatedly dropped onto a steel plate from a height of 45 cm and checked for visible cracks. The average number of falls until cracks were detected was recorded as the number of falls.

The binder compositions used to pelletize iron ore, which result in the appropriate dry strength and number of falls, are summarized in Table 1. 3. The composition contained 40 wt.% percent of the copolymer obtained from monomers ATBS and NaAA, and monomer C, and 60 wt.% salt of sodium carbonate.

Due to the difference in the chain length of the macromonomer, the weight percentages given in Table. 3 for monomer correspond to an equimolar amount of monomer C (for compositions 7 to 9 and compositions 10 to 12, respectively).

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Claims (22)

Table 3. Dry strength and number of drops of iron-containing pellets using binders according to the invention with different chain lengths Composition ATBS (weight. percent) NaAA (weight. percent) Monomer C Dry strength (N) Number pade- ny (wt. percent) Monomer C 7 47.8 49.8 2.4 VOBPEG 3000 16.0 4.1 8 48.6 50.5 0.9 VOBPEG 1100 15.1 3.2 9 48.8 50.8 0.4 VOBPEG 500 16.9 3.6 10 46.2 48.0 5.8 VOBPEG 3000 15.1 3.4 eleven 48.0 49.8 2.2 VOBPEG 1100 14.2 3.9 12 48.6 50.4 1.0 VOBPEG 500 15.6 3.9 13 46.4 48.24 5.39 VOBPEG 5800 14.2 2.9 CLAIM 1. The use of a copolymer in combination with at least one auxiliary pelletizing agent and an additional binder for pelletizing a metal-containing ore, where the copolymer contains monomeric units derived from: i) at least one anionic, monoethylenically unsaturated hydrophilic monomer A; ii) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer B and iii) at least one monomer C of formula (I) H ₂ C=C(R ¹ )-R ² -O(-CH ₂ -CH ₂ -O-)k-CH ₂ -CH ₂ -R ³ (I), where R ¹ means hydrogen or methyl; R ² means -OR ⁴ where R ⁴ means -(CH ₂ )n-, where n means an integer from 1 to 6; R ³ is hydrogen or -OH and k is a number from 0 to 300, and where the additional binder is an absorbent aluminum phyllosilicate, and where the pelletizing aid is a water-soluble material selected from the group consisting of sodium carbonate, sodium bicarbonate, silicate sodium, sodium phosphate, sodium stearate, sodium benzoate, sodium tartrate, sodium oxalate, sodium citrate, sodium acetate, the corresponding ammonium, potassium, calcium and magnesium salts of the above sodium, urea and calcium oxide salts. 2. The use according to claim 1, where R ³ means -OH. 3. Use according to any one of claims 1, 2, where k is a number from 1 to 300. 4. Use according to claim 3, wherein the additional binder is bentonite. 5. The use according to any one of claims 1 to 4, where k is a number from 5 to 150, preferably from 5 to 75, more preferably from 5 to 50 and even more preferably from 11 to 50. 6. Use according to any one of claims 1 to 5, wherein at least one monomer C is vinyloxybutyl polyethylene glycol, where k is preferably a number from 5 to 75. 7. Use according to any one of claims 1 to 6, wherein at least one monomer A contains at least one functional group selected from the group consisting of -COOH, -SO ₃ H, -PO ₃ H ₂ , their salts and mixtures of any of the above, wherein the more preferred at least one monomer A is 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or a salt thereof. 8. Use according to any one of claims 1 to 7, wherein at least one monomer B is selected from the group consisting of acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N,N'dimethylacrylamide, N,N'-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, uncharged vinylamides or mixtures thereof, and where preferably at least one monomer B is acrylamide. 9. Use according to any one of claims 1 to 8, wherein the copolymer contains from 0.1 to 15 wt.% and preferably from 0.5 to 4 wt.% of at least one monomer C of formula (I). 10. Use according to any one of claims 1 to 9, wherein the copolymer is water soluble. 11. Use according to any one of claims 1 to 10, wherein the metal-containing ore is selected from the group of Fe-containing ore, Cu-containing ore, Mo-containing ore, Ni-containing ore, Cr-containing ore or mixtures thereof, and Fe-containing ore is preferred. . 12. Composition for pelletizing metal-containing ore, including: i) a copolymer, where the copolymer contains monomer units derived from - 12 040350 a) at least one anionic, monoethylenically unsaturated hydrophilic monomer A; b) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer B and c) at least one monomer C of formula (I) H ₂ C=C(R ¹ )-R ² -O(-CH2-CH2-O-) _k -CH2-CH ₂ -R ³ (I), where R ¹ means hydrogen or methyl; R ² means -OR ⁴ where R ⁴ means -(CH ₂ ) _P -, where η means an integer from 1 to 6; R ³ is hydrogen or —OH, and k is a number from 0 to 300; and ii) a pelletizing aid, wherein the pelletizing aid is a water soluble material selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium silicate, sodium phosphate, sodium stearate, sodium benzoate, sodium tartrate, sodium oxalate, sodium citrate , sodium acetate, the corresponding ammonium, potassium, calcium and magnesium salts of the above salts of sodium, urea and calcium oxide. 13. A composition according to claim 12 wherein the pelletizing aid ii) is sodium carbonate. 14. A composition according to any one of claims 12 or 13, wherein the composition further comprises an aluminum phyllosilicate absorbent, wherein preferably the aluminum phyllosilicate absorbent is bentonite. 15. The composition according to any one of paragraphs. 12-14, where R ³ means -OH and/or k means a number from 1 to 300. 16. Composition according to any one of claims 12-15, where k is a number from 5 to 150, preferably from 5 to 75, more preferably from 5 to 50 and most preferably from 11 to 50. 17. Composition according to any one of claims 12 to 16, wherein at least one monomer C is vinyloxybutyl polyethylene glycol, where k is preferably a number from 5 to 75. 18. The composition according to any one of claims 12-17, where at least one monomer A of the copolymer i) contains at least one functional group from the group that contains -COOH, -SO ₃ H, PO ₃ H ₂ , their salts and mixtures of any of the above, wherein preferably at least one monomer A is 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or a salt thereof. 19. Composition according to any one of claims 12-18, wherein at least one monomer B is selected from the group consisting of acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N,N'dimethylacrylamide, N,N'-dimethylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, uncharged vinylamides or mixtures thereof, and where preferably at least one monomer B is acrylamide. 20. The composition according to any one of claims 12 to 19, wherein the copolymer designated as i) contains from 0.1 to 15 wt.% and preferably from 0.5 to 4 wt.% of at least one monomer C of formula (I ). 21. The composition according to any one of paragraphs. 12-20, where the copolymer designated as i) is water soluble. 22. The composition according to any one of paragraphs. 12-21, wherein the metal-bearing ore is selected from the group consisting of Fe-bearing ore, Cu-bearing ore, Mo-bearing ore, Ni-bearing ore, Cr-bearing ore, or mixtures thereof, and Fe-bearing ore is preferred. Eurasian Patent Organization, EAPO Russia, 109012, Moscow, Maly Cherkassky per., 2