COAL BINDER COMPOSITION

Abstract

The presently claimed invention relates to a briquette comprising coal fines and a binder composition comprising at least one homo- or copolymer of (meth)acrylic acid (i) and at least one alkyl(meth)acrylate-styrene-copolymer (ii), a method for manufacturing said briquette and the use of a binder composition for the agglomeration of coal fines.

Description

The presently claimed invention relates to a briquette comprising coal fines and a binder composition comprising at least one homo- or copolymer of (meth)acrylic acid (i) and at least one alkyl(meth)acrylate-styrene-copolymer (ii), a method for manufacturing said briquette and the use of a binder composition for the agglomeration of coal fines.

During coal mining coal fines are obtained in addition to lumps of coal. Further processing of said coal fines is possible, e.g. by using floatation processes. The thus obtained coal fines concentrate is briquetted and the obtained tailings which still contain a considerable amount of coal fines are discarded onto a mining waste tip. However, in some regions, e.g. South Africa, usually the whole coal fines fraction is dumped onto a mining waste heap without any further processing. Such a coal fines may comprise more than 20 wt.-% of unburnable minerals rendering the coal fines as such inopportune to use as fuel.

Large amounts of coal fines on mining waste tips lead to significant amounts of escaping coal dust which is undesirable and maybe in the future or already is prohibited by law in some countries. In some countries even existing mining waste heap have to be closed and the coal fines removed. Although direct combustion of coal fines having high ash content is not possible, such coal fines can be combusted in a plant provided that the coal fines are present as briquettes. Moreover, briquettes of course are much easier to transport compared to coal fines. Thus by using briquettes the combustion can take place where needed. However, for this purpose the briquettes need to be stable during transport and in particular resistant to damage by dropping from a certain height as transport from one vessel to another frequently occurs, e.g. when the pellets are moved from a train to a ship or the like. In case the briquettes break during transport or the surface is abraded due to friction undesired small particles are formed and even coal fines may be formed causing environmental contamination and, in case the worst comes to the worst, even dust explosions.

For briquette formation of most coal fines usually a polyvinyl alcohol (PVA) binder is added as a diluted solution that requires heating the PVA to a temperature of >80° C. for solubilization, which is undesirable from an economic point of view. Moreover, the mechanical stability of such PVA-containing briquettes still needs improvement.

Thus, the object of the presently claimed invention is to provide briquettes comprising coal fines and a binder composition which show a good mechanical stability and strength, whereby the mechanical stability and strength is developed at relatively low temperatures without the need to heat the binder composition.

The object is achieved by providing briquettes that comprise coal fines and a binder composition comprising at least one homo- or copolymer of (meth)acrylic acid (i) and at least one alkyl(meth)acrylate-styrene-copolymer (ii).

Thus, in one embodiment, the presently claimed invention is directed to a briquette comprising

A) coal fines and

B) a binder composition comprising

• • (i) at least one homo- or copolymer of (meth)acrylic acid and
  • (ii) at least one alkyl(meth)acrylate-styrene-copolymer.

Preferably the presently claimed invention is directed to a briquette comprising

A) coal fines and

B) a binder composition comprising

• • (i) at least one homo- or copolymer of (meth)acrylic acid, which is not an alkyl(meth)acrylate-styrene-copolymer and
  • (ii) at least one alkyl(meth)acrylate-styrene-copolymer.

In the sense of the presently claimed invention the term “briquette” denotes a compressed block of any shape including spheres, rectangles, squares, rods, broken strips and broken sheets.

In the sense of the presently claimed invention the term “coal fines” denotes the entirety of solid inorganic components comprising coal particles and ash particles. In the sense of the presently claimed invention the term “coal particles” denotes particles consisting substantially, i.e. >85 wt.-%, of carbon. The term “ash particles” denotes particles of non-coal minerals including silica, clay and pyrite.

Usually the coal particles make up at least 50 wt.-%, more preferably at least 60 wt.-% and most preferably at least 70 wt.-%, based on the total weight of the coal fines.

The coal fines may further comprise ash particles. Although a low ash particle content, e.g. 10 wt.-% or less, preferably 5 wt.-% or less, based on the total weight of the coal fines is preferable, the coal fines may comprise up to 40 wt.-% of ash particles determined according to standard gravimetric methods. The inventive pellets can still be utilized in a power plant, a coal liquefaction (Fischer-Tropsch/Sasol process) plant at such a high ash particle content. Preferably, the ash particle content is up to 25 wt.-%, based on the total weight of the coal fines. Coal fines with high ash particle content include waste coal, run-of-mine coal and freshly mined coal.

Preferably, the coal fines comprise at least 50 wt.-% coal particles having a particle diameter of less than 1 mm determined according to DIN 66165, more preferably comprise at least 75 wt.-% coal particles having a particle diameter of less than 1 mm and most preferably consist of coal particles having a particle diameter of less than 1 mm.

In a preferred embodiment the coal fines comprise at least 50 wt.-% coal particles having a particle diameter of less than 500 μm determined according to DIN 66165, more preferably comprise at least 75 wt.-% coal particles having a particle diameter of less than 500 μm and most preferably consist of coal particles having a particle diameter of less than 500 μm. In an especially preferred embodiment the coal fines comprise at least 50 wt.-% coal particles having a particle diameter of less than 300 μm determined according to DIN 66165, more preferably comprise at least 75 wt.-% coal particles having a particle diameter of less than 300 μm and most preferably consist of coal particles having a particle diameter of less than 300 μm.

Preferably, the coal fines comprise at least 50 wt.-% particles passing Tyler Mesh 16 sieve (1 mm sieve opening), more preferably comprise at least 75 wt.-% particles passing Tyler Mesh 16 sieve (1 mm sieve opening) and most preferably consist of particles passing Tyler Mesh 16 sieve (1 mm sieve opening). Preferably, the coal fines comprise at least 50 wt.-% particles passing Tyler Mesh 32 sieve (500 μm sieve opening), more preferably comprise at least 75 wt.-% particles passing Tyler Mesh 32 sieve (500 μm sieve opening) and most preferably consist of particles passing Tyler Mesh 32 sieve (500 μm sieve opening). Preferably, the coal fines comprise at least 50 wt.-% particles passing Tyler Mesh 48 sieve (300 μm sieve opening), more preferably comprise at least 75 wt.-% particles passing Tyler Mesh 48 sieve (300 μm sieve opening) and most preferably consist of particles passing Tyler Mesh 48 sieve (300 μm sieve opening).

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer (ii).

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) is selected from the group consisting of homopolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and at least one nonionic monomer; and

copolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and at least one nonionic monomer.

In the sense of the presently claimed invention the at least one “nonionic monomer” is a monomer which is electrically neutral. Preferably nonionic monomers are selected from the group consisting of methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylamide, methacrylamide, N-methylacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, N, N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-(2-hydroxypropyl)methacrylamide, N-methylolacrylamide, N-vinyfformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, poly(ethylene glycol)(meth)acrylate, poly(ethylene glycol) monomethyl ether mono(meth)acrylate, N-vinyl-2-pyrrolidone, glycerol mono((meth)acrylate), 2-hydroxyethyl(meth)acrylate, vinyl methylsulfone and vinyl acetate. More preferably nonionic monomers are selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate.

More preferably the homo- or copolymers of (meth)acrylic acid (i) are selected from the group consisting of homopolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and at least one nonionic monomer selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate; and

copolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and at least one nonionic monomer selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate.

Even more preferably the homo- or copolymers of (meth)acrylic acid (i) are selected from the group consisting of homopolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

homopolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts;

copolymers of acrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and acrylamide; and copolymers of methacrylic acid, optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts, and acrylamide.

In particular the at least one homo- or copolymer of (meth)acrylic acid (i) is comprising a copolymer of acrylic acid and acrylamide. Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) consists of a copolymer of acrylic acid and acrylamide. For example, a copolymer of acrylic acid and acrylamide is available as Alcotac® CB6 of BASF. It is further preferred that the at least one homo- or copolymer of (meth)acrylic acid (i) is comprising for exampie a polymer of acrylic acid, in particular polyacrylic acid. Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) consists of polyacrylic acid.

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) has a weight average molecular weight of ≥1 000 to ≤5 000 000 g/mol, more preferably in the range of ≥10 000 to ≤500 000 g/mol, determined according analysis via gel permeation chromatography.

Preferably the at least one copolymer of (meth)acrylic acid (i) is derived from a mixture comprising ≥50 wt.-%, more preferably ≥70 wt.-%, even more preferably ≥80 wt.-%, most preferably ≥90 wt.-%, methacrylic acid and/or acrylic acid, each optionally in form of its alkali metal salts, alkaline metal salts and ammonium salts. The remainder of the copolymers of (meth)acrylic acid (i) is derived from at least at least one nonionic monomer as defined above.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is different to the at least one homo- or copolymer of (meth)acrylic acid (i).

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is derived from a mixture comprising

at least one monomer A selected from the group consisting of esters of acrylic acid or methacrylic acid with n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol, dodecanol and stearyl alcohol

and at least one monomer B selected from the group consisting of styrene and-alpha-methyl-styrene.

Preferably the mixture comprises ≥20 to ≤90 wt.-%, more preferably ≥40 to ≤80 wt.-%, most preferably ≥50 to ≤70 wt.-%, of at least one monomer A, based on the total weight of the mixture. Preferably the mixture comprises ≥10 to ≤80 wt.-%, more preferably ≥20 to ≤60 wt.-%, most preferably ≥30 to ≤50 wt.-%, of at least one monomer B, based on the total weight of the mixture.

Preferably the at least one monomer A is selected from the group consisting of esters of acrylic acid or methacrylic acid with n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol, dodecanol or stearyl alcohol or mixtures thereof, more preferably with n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol, dodecanol or stearyl alcohol or mixtures thereof and most preferably with n-butanol, isobutanol, sec-butanol or tert-butanol.

The at least one alkyl(meth)acrylate-styrene-copolymer (ii) may also be derived from a mixture comprising other monomers in an amount of up to 10 wt.-%, preferably 5 wt.-% based on the total weight of the mixture. In case these other monomers are present, they are preferably selected from vinyl formate, vinyl acetate, vinyl propionate, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylamide, methacrylamide, vinyl chloride, vinylidene chloride, vinyl ethyl ether, ethylene, propylene, butadiene, isoprene, N-vinylpyrrolidone, vinylsulfonic acid and alkali metal salts thereof, acrylamidopropanesulfonic acid and alkali metal salts thereof, sulfonated styrene and alkali metal salts thereof, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, N-alkyl- and N-hydroxyalkylamides of ethylenically unsaturated C₃-C₆-mono- or dicarboxylic acids, diesters of dihydric alcohols of ethylenically unsaturated C₃-C₆-mono- or dicarboxylic acids, the vinyl or allyl esters of ethylenically unsaturated C₃-C₆-mono- or dicarboxylic acids, N,N′-divinyl- or N,N′-diallylurea derivatives or divinylaromatics.

In case other monomers are present usually not more than two other monomers are present, preferably, not more than one. Most preferably no other monomers are present.

The at least one alkyl(meth)acrylate-styrene-copolymer (ii) may also be present as a mixture of two or more alkyl(meth)acrylate-styrene-copolymers (ii) according to the invention. Usually not more than three alkyl(meth)acrylate-styrene-copolymers (ii) are present, preferably only one alkyl(meth)acrylate-styrene-copolymer (ii) is present.

In particular the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is comprising a butyl acrylate-styrene copolymer. Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii) consists of a butyl acrylate-styrene copolymer. For example, a butyl acrylate-styrene copolymer is available as Acronal@ S 728 of BASF.

It is further preferred, that the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is formulated in a ready to use formulation together with preferably the at least one homo- or copolymer of (meth)acrylic acid (i) which is not an alkyl(meth)acrylate-styrene-copolymer (ii). Preferably, the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is comprising a butyl acrylate-styrene copolymer which is formulated in a formulation which is comprising for example a copolymer of acrylic acid and acrylamide as the at least one homo- or copolymer of (meth)acrylic acid (i). Further preferred is that the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is comprising a butyl acrylate-styrene copolymer which is formulated in a formulation which is comprising for example a polymer of acrylic acid, in particular polyacrylic acid, as the at least one homo- or copolymer of (meth)acrylic acid (i). For example, a formulation comprising butylacrylate styrene copolymer and a polymer of acrylic acid in water is available as Alcotac® CBF60 from BASF.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii) has a weight average molecular weight of ≥1 000 to ≤2 000 000 g/mol, more preferably in the range of ≥1 000 to ≤1 000 000 g/mol, even more preferably in the range of ≥1 000 to ≤500 000 g/mol, determined according to gel permeation chromatography measurement.

Preferably the binder composition comprises at least one cross-linking agent (iii) selected from the group consisting of polymers having at least one functional group which is selected from the group comprising hydroxy, primary, secondary and tertiary amine, epoxy and aldehyde and polyvalent metal complexes.

The cross-linking can also be effected by the addition of alkali.

Preferably the polyvalent metal in the polyvalent metal complex is selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, zirconium, nickel, iron, cadmium, strontium, bismuth, beryllium, cobalt, lead, copper and antimony. Preferably the ligand for forming the polyvalent metal complex is selected from the group consisting of carbonic acid ion, acetic acid ion, oxalic acid ion, malic acid ion, hydroxyacetic acid ion, tartaric acid ion, acrylic acid ion, lactic acid ion, formic acid ion, salicylic acid ion, benzoic acid ion, gluconic acid ion, glutamic acid ion, glycine, alanine, ammonia, morpholine, ethylene diamine, dimethylaminoethanol, diethylaminoethanol, monethanolamine, diethanolamine and triethanolamine.

The polymers having at least one functional group which is selected from the group comprising hydroxy, primary, secondary and tertiary amine, epoxy and aldehyde comprise, as a rule, the substances known to the person skilled in the art, generally used for aminoplasts or phenol-formaldehyde resins and usually referred to as curing agents, such as ammonium sulfate or ammonium nitrate or inorganic or organic acids, for example sulfuric acid, formic acid, or acid-regenerating substances, such as aluminum chloride, aluminum sulfate, in each case in the customary, small amounts, for example in the range from 0.1% by weight to 10% by weight, based on the total amount of cross-linking agent (iii).

Phenol-formaldehyde resins (also referred to as PF resins) are known to the person skilled in the art, cf. for example Kunststoff-Handbuch, 2nd edition, Hanser 1988, volume 10 “Duroplaste”, pages 12 to 40.

In particular the binder composition further comprises at least one cross-linking agent (iii), whereas the cross-linking agent (iii) preferably is comprising a phenol formaldehyde resin. For example, phenol formaldehyde resins are available from BASF as Alcotac® CBX60 or from Resichem as Reslink® GTC 50.

Here, aminoplast resin is understood as meaning polycondensates of compounds having at least one carbamide group optionally partly substituted by organic radicals (the carbamide group is also referred to as carboxamide group) and an aldehyde, preferably formaldehyde.

All aminoplast resins known to the person skilled in the art, can be used as suitable aminoplast resin. Such resins and their preparation are described, for example, in Ullmanns Enzyklopädie der technischen Chemie, 4th newly revised and extended edition, Verlag Chemie, 1973, pages 403 to 424 “Aminoplaste”, and Ullmann's Encyclopedia of Industrial Chemistry, Vol. A2, VCH Veriagsgesellschaft, 1985, pages 115 to 141 “Amino Resins”, and in M. Dunky, P. Niemz, Holzwerkstoffe and Leime, Springer 2002, pages 251 to 259 (UF resins) and pages 303 to 313 (MUF and UF with a small amount of melamine).

Preferred aminoplast resins are polycondensates of compounds having at least one carbamide group, also partly substituted by organic radicals, and formaldehyde.

Particularly preferred aminoplast resins are urea-formaldehyde resins (UF resins), melamine-formaldehyde resins (MF resins) or melamine-containing urea-formaldehyde resins (MUF resins).

Very particularly preferred aminoplast resins are urea-formaldehyde resins, for example Kaurit® glue types from BASF SE.

Further very preferred aminoplast resins are polycondensates of compounds having at least one amino group, also partly substituted by organic radicals, and aldehyde, in which the molar ratio of aldehyde to amino group optionally partly substituted by organic radicals is in the range from 0.3 to 1.0, preferably from 0.3 to 0.60, particularly preferably from 0.3 to 0.45, very particularly preferably from 0.30 to 0.40.

Further very preferred aminoplast resins are polycondensates of compounds having at least one amino group —NH₂ and formaldehyde, in which the molar ratio of formaldehyde to —NH₂ group is in the range from 0.3 to 1.0, preferably from 0.3 to 0.60, particularly preferably from 0.3 to 0.45, very particularly preferably from 0.30 to 0.40.

Further very preferred aminoplast resins are urea-formaldehyde resins (UF resins), melamine-formaldehyde resins (MF resins) or melamine-containing urea-formaldehyde resins (MUF resins), in which the molar ratio of formaldehyde to —NH₂ group is in the range from 0.3 to 1.0, preferably from 0.3 to 0.60, particularly preferably from 0.3 to 0.45, very particularly preferably from 0.30 to 0.40.

Further very preferred aminoplast resins are urea-formaldehyde resins (UF resins) in which the molar ratio of formaldehyde to —NH₂ group is in the range from 0.3 to 1.0, preferably from 0.3 to 0.60, particularly preferably from 0.3 to 0.45, very particularly preferably from 0.30 to 0.40.

Said aminoplast resins are usually used in liquid form, generally suspended in a liquid suspending medium, preferably in aqueous suspension, but can also be used as a solid.

The solids content of the aminoplast resin suspensions, preferably aqueous suspension, is usually from 25 to 90% by weight, preferably from 50 to 70% by weight.

The aminoplast resins are prepared by known processes (cf. abovementioned Ullmann literature “Aminoplaste” and “Amino Resins”, and abovementioned literature Dunky et al.) by reacting the compounds containing carbamide groups, preferably urea and/or melamine, with the adehydes, preferably formaldehyde, in the desired molar ratios of carbamide group to aldehyde, preferably in water as a solvent.

The desired molar ratio of aldehyde, preferably formaldehyde, to amino group optionally partly substituted by organic radicals can also be established by addition of monomers carrying —NH₂ groups to formaldehyde-richer prepared, preferably commercial, aminoplast resins. Monomers carrying NH₂ groups are preferably urea or melamine, particularly preferably urea.

The resin constituents of the cross-linking agent (iii) can be used by themselves, i.e. for exampie aminoplast resin as the sole resin constituent of the cross-linking agent (iii) or PF resin as the sole constituent of the cross-linking agent (iii).

The resin constituents of the cross-linking agent (iii) can, however, also be used as a combination of two or more resin constituents of the cross-linking agent (iii).

The binder composition further comprises additives that have an advantageous effect on the overall characteristics of the briquette or the process for manufacturing briquettes. Suitable additives include defoaming agents, water-repellent agents, surfactants and coalescing solvents.

The defoaming agents that are suitable for the inventively used binder composition can be those commonly used in the art. In some non-limiting embodiments of the present invention, examples of defoaming agents that are suitable for the inventively used binder composition include, but are not limited to, polyol defoamers, polyether defoamers, mineral oil defoamers, silicone defoamers, or mixtures thereof. In some non-limiting embodiments of the present invention, the defoamers can be used in an amount of ≥0.01 wt.-% to ≤1.0 wt.-%, based on the total weight of the binder composition.

The surfactants that are suitable for the presently claimed invention include, but are not limited to, anionic surfactants, nonionic surfactants, cationic surfactants and combinations thereof.

Examples of anionic surfactants that are suitable for the presently claimed invention include, but are not limited to: alkylsulfates, alkylsulfonates, alkylbenzenesulfonates, alkyl polyoxyethylene ether sulfates, alkylpolyoxyethylene-propylene ether sulfates, sodium fatty alcohol succinic acid mono ester sulfonates, disodium fatty alcohol polyoxyethylene ether, sulfosuccinates, disodium fatty alcohol polyoxyethylene-propylene ether sulfosuccinates, alkylpolyoxyethylene phosphates, alkylpolyoxyethylene-propylene phosphates, and alkali metal salts and ammonium salts of fatty acids. Examples of nonionic surfactants that are suitable for the presently claimed invention include, but are not limited to: linear or branched alkyl alcohol polyoxyethylene ethers, linear or branched alkyl alcohol polyoxyethylene-propylene ethers, fatty acid polyoxyethylene monoesters, fatty acid polyoxyethylene-propylene monoesters. In some non-limiting embodiments of the present invention, the EO (ethylene oxide) numbers of polyoxyethylene section in nonionic surfactants determine the HLB value of the nonionic surfactants, and the HLB value of the nonionic surfactants is typically in the range of about 20 to 40.

The water-repellent agents that are suitable for the presently claimed invention include, but are not limited to, sodium oleates or organosilicon compounds such as alkoxysilanes.

The coalescing solvents that are suitable for the presently claimed invention include, but are not limited to, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether.

Preferably, the binder composition comprises

• ≥10 wt.-% to ≤70 wt.-% (i) at least one homo- or copolymer of (meth)acrylic acid,
• ≥10 wt.-% to ≤70 wt.-% (ii) at least one alkyl(meth)acrylate-styrene-copolymer,
• ≥0.1 wt.-% to ≤5 wt.-% (iii) at least one cross-linking agent,
• ≥20 wt.-% to ≤80 wt.-% water and
• ≥1 wt.-% to ≤80 wt.-% at least one additive selected from the group consisting of defoaming agents, water-repellent agents, surfactants and coalescing solvents.

More preferably, the binder composition comprises

• ≥20 wt.-% to ≤40 wt.-% (i) at least one homo- or copolymer of (meth)acrylic acid,
• ≥20 wt.-% to ≤40 wt.-% (ii) at least one alkyl(meth)acrylate-styrene-copolymer,
• ≥0.1 wt.-% to ≤5.0 wt.-% (iii) at least one cross-linking agent,
• ≥20 wt.-% to ≤80 wt.-% water and
• ≥1 wt.-% to ≤80 wt.-% at least one additive selected from the group consisting of defoaming agents, water-repellent agents, surfactants and coalescing solvents.

Preferably in the binder composition the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is different to the at least one homo- or copolymer of (meth)acrylic acid (i). In particular the at least one homo- or copolymers of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer (ii).

Preferably, the weight ratio of the amount of the at least one homo- or copolymer of (meth)acrylic acid (i) to the amount of the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is within the range of 1:25 to 25:1, more preferably within the range of 1:10 to 10:1, even more preferably within the range of 1:5 to 5:1 and most preferably within the range of 1:1 to 5:1.

Preferably the at least one homo- or copolymer of (meth)acrylic acid (i) is present in an amount of ≥0.05 to ≤1.0 wt.-%, more preferably in an amount of ≥0.1 to ≤0.8 wt.-%, most preferably in an amount of ≥0.1 to ≤0.5 wt.-%, based on the total weight of the briquette.

Preferably the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is present in an amount of ≥0.05 to ≤1.0 wt.-%, more preferably in an amount of ≥0.05 to ≤0.5 wt.-%, most preferably in an amount of ≥0.05 to ≤0.3 wt.-%, based on the total weight of the briquette.

Preferably the presently claimed invention is directed to a briquette comprising

A) ≥99.0 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

• • (i) ≥0.05 to ≤1.0 wt.-% of at least one homo- or copolymer of (meth)acrylic acid and
  • (ii) ≥0.05 to ≤1.0 wt.-% of at least one alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

More preferably the presently claimed invention is directed to a briquette comprising

A) ≥99.0 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

• • (i) ≥0.1 to ≤0.8 wt.-% of at least one homo- or copolymer of (meth)acrylic acid and
  • (ii) ≥0.05 to ≤0.5 wt.-% of at least one alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

Most preferably the presently claimed invention is directed to a briquette comprising

A) ≥99.4 to ≤99.9 wt.-% coal fines and

B) a binder composition comprising

• • (i) ≥0.1 to ≤0.5 wt.-% of at least one homo- or copolymer of (meth)acrylic acid and
  • (ii) ≥0.05 to ≤0.3 wt.-% of at least one alkyl(meth)acrylate-styrene-copolymer,

whereby each weight is based on the total weight of the briquette.

Preferably in the briquette the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is different to the at least one homo- or copolymer of (meth)acrylic acid (i). In particular the at least one homo- or copolymers of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer (ii).

In the sense of the presently claimed invention, the longitudinal direction of extension is preferably the maximum extension of the briquette. The transversal direction of extension is preferably the maximum extension of the briquette orthogonal (perpendicular) to the longitudinal direction of extension. Typically the longitudinal direction of extension is longer than the transversal direction of extension. As the briquette of the presently claimed invention has a longitudinal axis being substantially longer than its transversal axis it exhibits an oblong shape.

In the sense of the presently claimed invention, the length of the briquette corresponds to the longitudinal direction of extension of the briquette, the height corresponds to the maximum extension of the briquette orthogonal to the length and the width corresponds to the transversal direction of extension orthogonal to the length and orthogonal to the width (Cartesian space).

Preferably the length of the briquette is in the range of ≥1 to ≤10 cm, more preferably in the range of ≥2 to ≤8 cm, most preferably in the range of ≥2 to ≤4 cm. Preferably the height of the briquette is in the range of ≥0.5 to ≤6 cm, more preferably in the range of ≥1 to ≤5 cm, most preferably in the range of ≥1 to ≤2 cm. Preferably the width of the briquette is in the range of ≥1 to ≤10 cm, more preferably in the range of ≥2 to ≤8 cm, most preferably in the range of ≥2 to ≤4 cm.

In another aspect, the presently claimed invention is directed to a process for manufacturing a briquette as defined above comprising the steps of

a) mixing coal fines and a binder composition comprising (i) at least one homo- or copolymer of (meth)acrylic acid and (ii) at least one alkyl(meth)acrylate-styrene-copolymer to obtain a mixture;

b) forming the mixture obtained according to step a) into a block;

c) drying the block obtained according to step b) to obtain a briquette.

In step a) the coal fines and the binder composition are thoroughly mixed, e.g. in an Eirich mixer, for at least 1 and up to 30 minutes and then transported, e.g. by using a conveyor belt, to a briquetting apparatus wherein the briquettes are formed. Preferably the coal fines in step a) have a water content in the range of ≥5 wt.-% to ≤20 wt.-%, more preferably in the range of ≥5 wt.-% to ≤15 wt.-%, based on the total weight of the coal fines, determined according to standard gravimetric techniques, e.g. determination of water content via ASTM D2216-10.

In step b) the mixture obtained according to step a) is fed to a briquetting apparatus and formed into a block. The briquetting apparatus is preferably a briquetting apparatus that included briquetting rollers. The mixture is fed to the briquetting rollers. The rollers compress the mixture.

One or more of the rollers preferably has pockets formed therein which pockets assist in defining the shape of the briquettes. The rollers also apply an amount of shear to the mixture as it passes through the briquetting apparatus.

In step c) the block is dried for a period of ≥12 to ≤48 h, more preferably for a period of ≥18 to ≤36 h. The curing temperature is preferably in the range of ≥10 to ≤45° C., more preferably in the range of ≥15 to ≤35° C. Thus, no heating of the briquettes after formation is necessary as the curing of the briquettes already occurs at room temperature.

Preferably in the process of manufacture the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is different to the at least one homo- or copolymer of (meth)acrylic acid (i). In particular the at least one homo- or copolymers of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer (ii).

In another aspect, the presently claimed invention is directed to the use of a binder combination, as defined above, for the agglomeration of coal fines.

In still another aspect, the presently claimed invention is directed to the use of a binder combination comprising (i) at least one homo- or copolymer of (meth)acrylic acid, as defined above, and (ii) at least one alkyl(meth)acrylate-styrene-copolymer, as defined above, for the agglomeration of coal fines.

Preferably for the use of the binder composition for the agglomeration of coal fines the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is different to the at least one homo- or copolymer of (meth)acrylic acid (i). In particular the at least one homo- or copolymers of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer (ii).

Although the invention has been described with respect to specific embodiments and examples, it should be appreciated that other embodiments utilizing the concept of the present invention are possible without departing from the scope of the invention. The present invention is defined by the claimed elements, and any and all modifications, variations, or equivalents that fall within the true spirit and scope of the underlying principles.

FIGURE

The FIGURE provided herein represents an example of particular embodiments of the invention and is not intended to limit the scope of the invention. The FIGURE is to be considered as providing a further description of possible and potentially preferred embodiments that enhance the technical support of one or more non-limiting embodiments.

SHORT DESCRIPTION OF THE FIGURE

FIG. 1 Cumulative % passing as a function of actual size

FIG. 1 describes in particular the cumulative % passing as a function of actual size with regard to for example coal fines. The size of coal fines according to FIG. 1 is in particular suitable for a briquette formation in presence of a binder composition comprising at least one homoor copolymer of (meth)acrylic acid (i), which is not a alkyl(meth)acrylate-styrene-copolymer (ii) and at least one alkyl(meth)acrylate-styrene-copolymer (ii). For example the coal fines according to FIG. 1 can be used in a method for manufacturing said briquette. In particular the binder composition according to the present invention can for example be used for the agglomeration of coal fines according to FIG. 1.

EXAMPLE

The invention is further described by the following examples. The examples provided herein represent practical support for particular embodiments of the invention and are not intended to limit the scope of the invention. The examples are to be considered as providing a further description of possible and potentially preferred embodiments that demonstrate the relevant technical work of one or more non-limiting embodiments.

Coal fines are supplied by a coal mine. The particle size distribution was determined using Tyler Mesh 16 sieve (1 mm sieve opening). FIG. 1 shows the cumulative particle size distribution of the coal fines.

Binder Compositions

Binder composition 1 comprising Acronal@ S728 (available from BASF SE, butyl acrylate-styrene copolymer) and Alcotac® CB 6 (available from BASF SE, copolymer of acrylic acid and acryl amide) in water.

Binder composition 2 comprising Acronal@ S728 (available from BASF SE, butyl acrylate-styrene copolymer) and Alcotac® CB 6 (available from BASF SE, copolymer of acrylic acid and acryl amide) and Reslink® GTC 50 (available from Resichem, India, a phenol-formaldehyde resin) in water.

Binder composition 3 comprising polyvinyl alcohol in water.

Binder composition 4 comprising a formulation of butylacrylate styrene copolymer and a polymer of acrylic acid in water (available as Alcotac® CBF60 from BASF).

Binder composition 5 comprising a formulation of butylacrylate styrene copolymer and a polymer of acrylic acid in water (available as Alcotac® CBF60 from BASF) combined with a phenol formaldehyde resin (available as Alcotac® CBX60 from BASF).

Formulation of Briquettes

Example 1

The binder composition 1 was mixed with coal fines. The mixture was thoroughly mixed. The mixture was transferred to a briquetting roller and briquettes were formed.

Example 2

The process was carried out as described in example 1 except for using binder composition 2 instead of binder composition 1.

Comparative Example 3

The process was carried out as described in example 1 except for using binder composition 3 instead of binder composition 1.

Example 4

The process was carried out as described in example 1 except for using binder composition 4 instead of binder composition 1.

Example 5

The process was carried out as described in example 1 except for using binder composition 5 instead of binder composition 1.

The dosage of binder composition in the examples 3, 4 and 5 were as follows:

Example 3 (comparative): 0.5 wt %

Example 4: 0.07 wt %

Example 5: 0.13 wt %

In Example 5 the binder composition additionally is comprising a crosslinker in a dosage of 0.05% (liquid).

Strength Test

The strength of the briquettes was tested in a drop test. In the drop test the briquette was continuously dropped from a height of 2 meters onto a concrete surface until it completely shatters. The drop test was carried out to test the green strength of the briquette, whereby the briquette was in the green state and had undergone no form of curing. Besides the cured strength of the briquettes was tested, whereby the briquette was allowed to cure at room temperature for a period of 24 hours after formation of the briquette.

The strength of the briquettes was tested in a compressive strength. In the compression strength test, 20 briquettes were individually compressed to break in pieces and data recorded per KgF (kilogram-force). The calculated corresponding SI unit in Newton [N] is given in brackets (1 KgF=9.80665 N). The compression test was carried out to test the green compression strength (Day 0) of the briquette, whereby the briquette was in the green state and had undergone no form of curing. Besides the cured strength (Day 2) of the briquettes was tested, whereby the briquette was allowed to cure at room temperature for a period of 48 hours after formation of the briquette.

The strength of the briquettes was tested in a tumbling test. In the tumbling test, 20 briquettes were put in a tumbling drum, rotating at 60 rpm for 10 minutes to observe the amount (% of briquettes) of fines generated from the briquettes in the tumbling drum. The tumbling test was carried out on the green briquettes (Day 0) of the briquette production, whereby the briquette were in the green state and had undergone no form of curing. Besides the cured tumbled briquettes (Day 2) of the briquettes were tested, whereby the briquette were allowed to cure at room temperature for a period of 48 hours after formation of the briquette.

Table 1 reflects the number of drops of the briquette until the briquette was shattered.

	Green strength
	test	Cured strength test
	Example 1	4	4
	Example 2	4	4
	Comparative	4	4
	example 3

The examples 1 and 2 in table 1 demonstrate that the inventively claimed binder composition leads to the formation of briquettes having a strength that is equal to the strength of briquettes that were formed by using polyvinyl alcohol (comparative example 3).

	Green strength
	test	Cured strength test
	Example 4	1	3
	Example 5	1	5
	Comparative	1	3
	example 3

The examples 4 and 5 in table 2 demonstrate that the inventively claimed binder composition leads to the formation of briquettes having a strength that is equal to or better than the strength of briquettes that were formed by using polyvinyl alcohol (comparative example 3). In particular the presence of for example a phenol formaldehyde resin in the binder composition (example 5) surprisingly shows better results with regard to cured strength test in comparison to example 3. Table 3 reflects the average compression strength of the briquette in Day 0 for green and in Day 2 for cured briquettes.

	Green	Cured
	Compression strength	Compression strength
Example 4	2 KgF (= 19.61 N)	4 KgF (= 39.23 N)
Example 5	3 KgF (= 29.42 N)	7 KgF (= 68.65 N)
Comparative example 3	1 KgF (= 9.81 N)	4 KgF (= 39.23 N)

The results in table 3 for example surprisingly show that the binder composition of the present invention in particular with regard to example 4 and 5 lead to equal or better compression strength (green and cured) in comparison to example 3 where polyvinyl alcohol is used in the binder composition. In particular the presence of for example a phenol formaldehyde resin in the binder composition (example 5) surprisingly shows better results with regard to green and cured compression strength in comparison to example 3.

Table 4 reflects the tumble test strength of the briquette in Day 0 for green and in Day 2 for cured briquettes. The lower the amount of fines generated, the better the briquettes.

	Green Tumble Test	Cured Tumble Test
Example 4	4.33%	2.71%
Example 5	3.19%	1.36%
Comparative example 3	8.33%	2.85%

The results in table 4 for example surprisingly show that the binder composition of the present invention in particular with regard to example 4 and 5 lead to better tumble test strength (green and cured) in comparison to example 3 where polyvinyl alcohol is used in the binder composition. In particular the presence of for example a phenol formaldehyde resin in the binder composition (example 5) surprisingly shows better results with regard to green and cured tumble test in comparison to example 3.

Claims

1: A briquette comprising

A) coal fines and

B) a binder composition comprising (i) at least one homo- or copolymer of (meth)acrylic acid and (ii) at least one alkyl(meth)acrylate-styrene-copolymer.

2: The briquette according to claim 1, wherein the coal fines comprise at least 50 wt.-% coal particles passing Tyler Mesh 16 sieve, 1 mm sieve opening.

3: The briquette according to claim 1, wherein the coal fines have an ash particle content of up to 40 wt.-% determined according to a gravimetric method.

4: The briquette according to claim 1, wherein the binder composition further comprises at least one cross-linking agent (iii) selected from the group consisting of:

a polymer having at least one functional group selected from the group consisting of hydroxy, primary amine, secondary amine, tertiary amine, epoxy and aldehyde; and

a polyvalent metal complex.

5: The briquette according to claim 1, wherein the at least one homo- or copolymer of (meth)acrylic acid (i) is not an alkyl(meth)acrylate-styrene-copolymer.

6: The briquette according to claim 1, wherein the at least one homo- or copolymer of (meth)acrylic acid (i) is selected from the group consisting of:

a homopolymer of acrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt;

a homopolymer of methacrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt;

a copolymer of acrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt, and at least one nonionic monomer; and

a copolymer of methacrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt, and at least one nonionic monomer.

7: The briquette according to claim 1, wherein the at least one homo- or copolymer of (meth)acrylic acid (i) is selected from the group consisting of:

a homopolymer of acrylic acid, optionally in a form of an alkali metal salts, an alkaline metal salt, or an ammonium salt;

a homopolymer of methacrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt;

a copolymer of acrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt, and at least one nonionic monomer selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate; and

a copolymer of methacrylic acid, optionally in a form of an alkali metal salt, an alkaline metal salt, or an ammonium salt, and at least one nonionic monomer selected from the group consisting of acrylamide, methacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-methylolacrylamide, methacrylate, ethyl acrylate, propyl acrylate and butyl acrylate.

8: The briquette according to claim 1, wherein the at least one homo- or copolymer of (meth)acrylic acid (i) has a weight average molecular weight of ≥1 000 to ≤5 000 000 g/mol determined according to g gel permeation chromatography measurement.

9: The briquette according to claim 1, wherein the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is derived from a mixture comprising:

at least one monomer A selected from the group consisting of an ester of acrylic acid or methacrylic acid with n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol, dodecanol and stearyl alcohol and

at least one monomer B selected from the group consisting of styrene and-alpha-methyl-styrene.

10: The briquette according to claim 1, wherein the at least one alkyl(meth)acrylate-styrene-copolymer (ii) has a weight average molecular weight of ≥1 000 to ≤2 000 000 g/mol determined according to a gel permeation chromatography measurement.

11: The briquette according to claim 1, wherein the at least one homo- or copolymer of (meth)acrylic acid (i) is present in an amount of ≥0.05 to ≤1.0 wt.-% based on the total weight of the briquette.

12: The briquette according to claim 1, wherein the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is present in an amount of ≥0.05 to ≤1.0 wt.-% based on the total weight of the briquette.

13: The briquette according to claim 1, wherein coal fines are present in an amount of ≥99.0 to ≤99.9 wt.-%, the at least one homo- or copolymer of (meth)acrylic acid (i) is present in an amount of ≥0.05 to ≤1.0 wt.-% and the at least one alkyl(meth)acrylate-styrene-copolymer (ii) is present in an amount of ≥0.05 to ≤1.0 wt.-%, each based on the total weight of the briquette.

14: A process for manufacturing the briquette of claim 1, comprising:

a) mixing coal fines and a binder composition comprising (i) at least one homo- or copolymer of (meth)acrylic acid and (ii) at least one alkyl(meth)acrylate-styrene-copolymer to obtain a mixture;

b) forming the mixture obtained according to step a) into a block; and

c) drying the block obtained according to step b) to obtain a briquette.

15: The process according to claim 14, wherein the coal fines in step a) have a water content in the range of ≥5 wt.-% to ≤20 wt.-%, based on the total weight of the coal fines, determined according to a gravimetric method.

16. (canceled)