WO2021140170A1

WO2021140170A1 - Pressure agglomerates of mineral material and processes for producing them

Info

Publication number: WO2021140170A1
Application number: PCT/EP2021/050222
Authority: WO
Inventors: Angela Beveridge; Amarish SAMEL; Carlos D SILVA GAXIOLA; Julie Mortimer; Adrian Mauricio VILLANUEVA BERINDOAGUE; Stefan Stein
Original assignee: Basf Se
Priority date: 2020-01-10
Filing date: 2021-01-08
Publication date: 2021-07-15

Abstract

The present invention defines a pressure agglomerate comprising: A) mineral particles; and B) a binder in which the binder is formed from a binder product, which binder product comprises a particulate water-soluble organic anionic or non-ionic polymer of one or more water-soluble ethylenically unsaturated monomers and which water-soluble organic anionic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g, wherein the particulate water-soluble organic anionic or non-ionic polymer has a particle size of at least 90% by weight below 425 µm, in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder. The invention also relates to a process of manufacturing said pressure agglomerate and the use of a binder comprising such a particulate water-soluble organic anionic or non-ionic polymer for the manufacture of pressure agglomerates containing mineral particles.

Description

Pressure Agglomerates of Mineral Material and Processes for Producing Them

Background of the Invention

Field of the Invention

The present invention relates to pressure agglomerates comprising mineral particles and a binder comprising at least one organic polymeric binder. The present invention also provides a process for producing mineral ore pressure agglomerates. The pres sure agglomerates may for instance be briquettes or extrudates.

Description of the Prior Art

In the mining industry mineral materials to be processed, such as metal -containing ores or coal fines, can be formed into pressure agglomerates, such as briquettes or extrudates, for convenient handling. Pressure agglomerates are typically made by compressing a mixture of the mineral material and a binder. Nevertheless, such pres sure agglomerates should have sufficient strength and tolerance to abrasion for trans portation and firing. In order to achieve pressure agglomerates of acceptable strength and tolerance generally large amounts of binder are used.

Typically, binders that are used to make pressure agglomerates, such as briquettes, include molasses, lignosulphonates, bitumen, clays, or cementing formulations. Doses of binders that are typically required are in the order of from 5 to 25% by weight which would involve significant bulk handling of the binder and binder mineral mixture. In fact, the physical mixing of such high levels of these binders with the mineral material to be pressure agglomerated is quite a challenge, since these binders are often very viscous and achieving uniform distribution throughout the mineral particulates is often quite difficult. Further, such high levels of binder inevitably mean that the so formed pressure agglomerates contain significantly less mineral material. Furthermore, the addition of high levels of such binders may also introduce a higher proportion of impu rities. For briquette formation of most coal fines frequently a polyvinyl alcohol (PVA) binder is added as diluted solution that requires heating the PVA to a temperature of >80°C for solubilisation. This can be undesirable from an economic point of view. Moreover, the mechanical stability of such PVA containing briquettes needed to be improved.

WO 2016189044 attempts to solve this problem 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). In this disclosure there is no disclosure that the at least one homo- or copolymer of (meth) acrylic acid (i) component of the binder will be added in the form of particles, rather the disclosure indicates that the composition would be water based and there fore the said polymer would be an aqueous solution.

WO 2013/079647 is directed to a binder for binding a metal bearing substrate, in par ticular metal bearing powder. The binder comprises a waterborne binder and a ther moplastic material with the weight ratio between the binder and the metal bearing sub strate being between 1 :200 to 1 :5.

Pressure agglomerates such as briquettes or extrudates generally require that the mixture of mineral and binder compressed using a significant pressure. Typically, the amount of pressure required to form a pressure agglomerates such as a briquette would be at least 50 kg force/cm² (at least 4.9 mega pascals (MPa)). This is quite a different process from pelletisation processes where the mineral and binder are not compressed but instead formed as green pellets generally using a balling process, for instance on balling discs or balling drums.

US 2014/0033872 describes binder compositions for agglomerating iron ore fines which comprise (a) about 30 to about 80% by weight one or more types of anionic or non-ionic acrylamide containing polymer; (b) about 10 to about 35% by weight one or more types of inorganic or organic monomeric electrolyte; and (c) about 10 to about 35% one or more types of finely ground wood fibre. The patent application also de scribes a process for preparing iron ore pellets with the binder compositions. In the de scription reference is also given to the term pellet referring to a small particle created by agglomerating the mixture comprising iron ore pellets, the binder and a liquid, such as water. It is also indicated that such mixtures may also be agglomerated or com pressed into shapes other than pellets, for example briquettes or other appropriate shapes.

US 6113844 relates to an ore pelletisation process which involves adding binder poly mer to particulate ore and moisture in order to form an intimate mixture of ore, binder polymer and moisture. The mixture is formed into green pellets and then fired. The ref erence describes that a water-soluble treatment polymer is included into the intimate mixture and that this water-soluble treatment polymer has a molecular weight from 1000 to 20,000 and is a synthetic polymer formed by polymerising water-soluble eth- ylenically unsaturated anionic monomer or water-soluble ethylenically unsaturated monomer blend containing at least 50% by weight anionic monomer.

US 5002607 describes a process for making pellets of a particulate metal ore by dis tributing a binder comprising water-soluble polymer particles throughout the particulate ore in the presence of water to form an initial mix. The initial mix is homogenously mixed to form a moist pelletisable mixture which is then pelletised. The binder com prises aggregates of polymer particles having a size mainly above 100 pm and in which the aggregates disintegrate during the process.

US 4728537 teaches a pelletisation process in which finely divided mineral ore is pelletised using a water-soluble synthetic polymer. The polymer is said to be prefera bly in the form of beads made by reverse-phase polymerisation and all having a size of below 300 pm.

It is an objective of the present invention to provide pressure agglomerates of mineral particles of improved characteristics, such as strength and abrasion tolerance and a process for making them. Further, an objective of the present invention is to provide such a process in which binder can be conveniently incorporated with the mineral par ticles. It is further still an objective to achieve the desired strength and abrasion toler ance characteristics of the formed pressure agglomerates and convenient application of the binders as well as maintaining or improving dose sufficiency. Summary of the Invention

These objectives have been achieved in a first aspect of the invention by providing a pressure agglomerate comprising:

A) mineral particles; and

B) a binder in which the binder is formed from a binder product, which binder product comprises a particulate water-soluble organic anionic or non-ionic polymer of one or more water- soluble ethylenically unsaturated monomers and which water-soluble organic anionic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g, wherein the particulate water-soluble organic anionic or non-ionic polymer has a parti cle size of at least 90% by weight below 425 pm, in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder.

In a further aspect of the invention we provide a process of manufacturing a pressure agglomerate comprising:

A) mineral particles; and

B) a binder which process comprises the steps of: a) mixing the mineral particles, water and a binder product that comprises particulate water-soluble organic polymer to obtain a mixture; b) forming the mixture obtained according to step a) into a block or cylinder by com pression; and c) drying the block or cylinder obtained according to step b) to obtain the pressure ag glomerate, in which the particulate water-soluble organic polymer is formed from one or more water-solu ble ethylenically unsaturated monomers and which water-soluble organic anionic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g, wherein the particulate water-soluble organic anionic polymer has a particle size of at least 90% by weight below 425 pm, in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder.

The invention also includes pressure agglomerates obtainable by this process.

The invention further relates to the use of a binder product that comprises a particulate water-soluble organic anionic or non-ionic polymer of one or more water-soluble eth- ylenically unsaturated monomers and which water-soluble organic anionic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g and having a particle size of at least 90% by weight below 425 pm and in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder for the manufacture of pressure ag glomerates containing mineral particles.

Detailed Description

The term pressure agglomerate is intended to include agglomerates of particulate min eral material that have been formed by compression. This may, for instance, be extru- dates, where the mineral particles and binder have been compressed by extruding through a shaped opening in a die, or briquettes. 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.

The mineral particles may be selected from particulate material derived from coal or metal ores or sludges or other wastes resulting from metal or metal alloy production. The coal may be in the form of coal fines. Metal ores include for instance iron ore which may typically be haematite or magnetite. Other metal ores include nickel ore, manganese or, chrome ore or ferro materials such as ferro-chrome or ferro-manga- nese. Another mineral material includes steel manufacturing process by-products that are iron rich. By by-products we mean incidental or secondary products made in the manufacture or synthesis of steel. Typically, these by-products may be sludges, slag, dust or scale. Generally, these by-products, such as sludges, slag, dusts or scale, have a high metallic content. Dust may for instance include ESP dust which is likely to be dust from electrostatic precipitator is, for instance a dust removal filter. Scale, which is often known as mill scale, is generally the flaky surface of hot rolled steel, consisting of the mixed iron oxides iron (II) oxide (FeO), iron (III) oxide (Fe2C>3), and iron (II, III) oxide (Fe3C>4, magnetite). Other mineral materials include ferrosilicon or flu orspar. Desirably the mineral particles are selected from the group consisting of coal fines, iron ore fines, particulate mill scale, particulate nickel ore, particulate chrome ore and particulate ferroalloys.

In some cases, the mineral particles would be processed to reduce the particle size to a size that would be suitable for forming pressure agglomerates. In other cases, the mineral particles would be in a form where the particle sizes are suitable for pro cessing to form pressure agglomerates. Suitably, the mineral particles have a size of less than 1 cm, typically 5 mm or less. Specifically, suitable mineral particles tend to be less than 1 cm in all dimensions, typically 5 mm or less in all dimensions. The parti cle size is determined according to DIN 66165.

Desirably the mineral particles contain coal fines. The term coal fines in this invention denotes total composition comprising the coal fines and in general the entirety of the solid inorganic components comprising coal particles and ash particles. In the pres ently claimed invention the term coal particles denotes particles containing substan tially i.e. >85 weight % of carbon. The term ash content denotes components of non coal materials including silica, clay and pyrite.

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

The coal fines may be constituents of noncoal materials, including silica, clay and py rite which are often referred to as ash content because they are noncombustible. Alt hough a low ash content, for instance 10 weight % or less, preferably 5 weight % or less, based on the total weight of the coal fines is preferable, the coal fines may com prise up to 40 weight % of ash content determined according to standard gravimetric methods. The inventive pressure agglomerates formed from coal particles can still be used in a powerplant, a coal liquefaction (Fischer-Tropsch/Sasol process) plant at such a high ash content. Preferably, the ash content is up to 25 weight %, based on the total weight of the coal fines. Coal fines with high ash content include waste coal, run off mine coal and freshly mined coal.

Preferably, the coal fines comprise at least 50 weight % coal particles having a diame ter of less than 1 cm determined according to DIN 66165, more preferably comprise at least 75 weight % coal particles having a particle diameter of less than 1 cm, suitably less than 5 mm, and more suitably less than 1 .5 mm, more preferably still 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 weight % coal particles having a particle diameter of less than 500 pm determined according to DIN 66165, more preferably comprise at least 75 weight % coal particles having a particle diame ter of less than 500 pm. In an especially preferred embodiment, the coal fines com prise at least 50 weight % coal particles having a particle diameter of less than 300 pm determined according to DIN 66165, more preferably comprise at least 75 weight % coal particles having a particle diameter of less than 300 pm and most preferably con sist of coal particles having a particle diameter of less than 300 pm.

Preferably, the coal fines comprise at least 50 weight % particles passing Tyler Mesh 16 sieve (1 mm sieve opening), more preferably comprise at least 75 weight % parti cles passing Tyler Mesh 16 sieve (1 mm sieve opening). Preferably, the coal fines comprise at least 50 weight % particles passing Tyler Mesh 32 sieve (500 pm sieve opening), more preferably comprise at least 75 weight % particles passing Tyler Mesh 32 sieve (500 pm sieve opening) and most preferably consist of particles passing Ty ler Mesh 32 sieve (500 pm sieve opening). Preferably, the coal fines comprise at least 50 weight % particles passing Tyler Mesh 48 sieve (300 pm sieve opening), more preferably comprise at least 75 weight % particles passing Tyler Mesh 48 sieve (300 pm sieve opening) and most preferably consist of particles passing Tyler Mesh 48 sieve (300 pm sieve opening). Iron ores are rocks and minerals from which metallic iron can be extracted. Iron ores used as the particulate mineral in the present invention may be in the form of haema tite (Fe2C>3), magnetite (Fe3C>4), goethite (FeO(OFI)), limonite (FeO(OFI).n(Fl20)) or si- derite (FeCC>3). Iron bearing sedimentary rocks such as Taconite and rocks containing iron oxide and banded quartz such as Itabirite may also be used as the particulate mineral. The iron ore used in the process of the present invention may contain parti cles up to 1 cm in diameter but may contain a substantial amount of fines. Desirably, the iron ore has a particle diameter of up to 5 mm, typically 1 .5 mm or less, for in stance 1.1 mm or less. Such iron ore fines are particles of iron ore that are substan tially of small particle size, for example less than about 250 pm. Typically, 80% by weight of the iron ore comprises less than 250 pm, often less than 150 pm and in some cases less than 100 pm. In some cases, the iron ore may comprise a significant amount of fines by weight. In some cases, 90% by weight of the iron ore may be less than 250 pm, often less than 150 pm and in some cases less than 100 pm.

The particulate water-soluble polymer comprised in the binder may be anionic or non ionic. It should be formed from one or more water-soluble ethylenically unsaturated monomers.

Chromium ore is generally the mineral chromite. Chromite is a mineral that is an iron chromium oxide which generally has the formula of FeCr₂0₄. Chromite ore is typically obtained in a mining operation. It is often crushed and processed to form a chromite concentrate. The chromite concentrate may be combined with a reducing component such as coal or coke and at high temperatures the chromite can be reduced to pro duce ferrochrome, which is an example of a ferroalloy. A chromite concentrate with or without reducing component i.e. coal or coke may be formed into briquettes in accord ance with the present invention. The crushed and processed chromite concentrate may have particles up to 1 cm but often have particles of smaller dimensions, for in stance up to 5 mm or up to 1 .2 mm. Frequently a large proportion of the chromite ore may be less than 500 pm, frequently less than 250 pm, often less than 150 pm and in some cases less than 100 pm. Manganese ores are typically oxides or carbonates of manganese and include the minerals pyrolusite, romanechite, manganite and hausmannite. Examples of manga nese carbonate ores include rhodochrosite, rhodonite and braunite. Pyrolusite is gen erally considered to be the most important manganese ore. Manganese ore is typically used to produce metallic alloys, for instance ferromanganese, which is an example of a ferroalloy. For the production of ferromanganese, the manganese ore may be mixed with iron ore and carbon and then reduced either in a blast furnace or in an electric arc furnace. Typically, the manganese ore, iron ore and carbon, for instance as coal or coke, may be formed into a briquette in accordance with the present invention. Typi cally, the manganese ore would be crushed and processed to produce a manganese ore concentrate. The crushed and processed manganese ore concentrate may have particles up to 1 cm but often have particles of smaller dimensions, for instance up to 5 mm or up to 1 .2 mm. Frequently a large proportion of the manganese ore may be less than 500 pm, frequently less than 250 pm, often less than 150 pm and in some cases less than 100 pm.

Suitably, the particulate water-soluble polymer is non-ionic and may be formed from one or more water-soluble ethylenically unsaturated non-ionic monomers. Examples of water-soluble ethylenically unsaturated non-ionic monomers include acrylamide, methacrylamide, hydroxy alkyl acrylates and allyl alkyl ethers. Typically, particulate water-soluble non-ionic polymers may be formed by the polymerisation of (meth) acrylamide (i.e. acrylamide or methacrylamide), optionally in the presence of other wa ter-soluble ethylenically unsaturated non-ionic monomers. It is possible that the at least one water-soluble ethylenically unsaturated non-ionic monomer is co-polymer- ised with other non-ionic monomers, such as vinyl acetate, styrene and alkyl acrylates, provided that the amount of these monomers included does not render the polymer water-insoluble. Desirably, the particulate water-soluble non-ionic polymer is the ho mopolymer of (meth) acrylamide.

Suitably, particulate water-soluble anionic polymer is formed from at least one water- soluble ethylenically unsaturated anionic monomer, optionally in combination with at least one water-soluble ethylenically unsaturated non-ionic monomer. The at least one water-soluble ethylenically unsaturated monomer may be any water-soluble ethylenically unsaturated monomer that carries an acid group or its salt thereof. Suita ble acid groups may include carboxylic acids, sulphonic acids, sulphuric acid, phos phoric acids or phosphoric acids. By referring to specific ethylenically unsaturated ani onic monomers we also include the corresponding salts thereof by this definition. We also include the corresponding anhydride of an acid group in the definition of water- soluble ethylenically unsaturated anionic monomer.

Typically, suitable water-soluble ethylenically unsaturated anionic monomers may in clude monomers bearing one or more carboxylic acid groups or sulphonic acid groups or their salts thereof. Such at least one water-soluble ethylenically unsaturated anionic monomers bearing carboxylic acid groups or sulphonic acid groups or their salts may be co-polymerised with water-soluble ethylenically unsaturated non-ionic monomers, such as (meth) acrylamide. Suitable water-soluble ethylenically unsaturated anionic monomers include monomers selected from the group consisting of acrylic acid, meth- acrylic acid, maleic acid, fumaric acid, itaconic acid, ethacrylic acid, crotonic acid, mo noesters of ethylenically unsaturated dicarboxylic acids, such as mono methyl male- ate, mono methyl fumarate, mono n-butyl maleate, mono n-butyl fumarate, styrene carboxylic acids, maleic anhydride, itaconic anhydride, allyl sulphonic acid, vinyl sul phonic acid, 2-acrylamido-2-methyl propane sulphonic acid, vinylphosphonic acid, 2- hydroxy ethyl methacrylate phosphate and their respective salts thereof.

Preferred particulate water-soluble anionic polymers include the homopolymers of acrylic acid (or salts thereof), methacrylic acid (or salts thereof) or copolymers of (meth) acrylic acid (or salts thereof) and (meth) acrylamide. Desirably, the salts of said particulate water-soluble anionic polymers are alkali metal salts, alkaline earth metal salts or ammonium salts. Particularly suitable salts include potassium salts or sodium salts. A more preferred particulate water-soluble anionic polymer includes the copoly mer of sodium acrylate and acrylamide.

The particulate water-soluble anionic polymer may contain any proportion of anionic monomer units with the remainder being non-ionic monomer units. The ethylenically unsaturated anionic monomer may be present in an amount in the range of from 1 to 100 % by weight, based on the total weight of monomers, the remainder being made up of ethylenically unsaturated non-ionic monomers. Desirably, the amounts of the re spective monomers used to form the particulate water-soluble anionic polymer may comprise, for instance, from 1% to 100 %, desirably from 1% to 99%, suitably from 5% to 95%, by weight of water-soluble ethylenically unsaturated anionic monomer; and from 0% to 99%, desirably from 1% to 99% suitably from 5% to 95%, by weight of (meth) acrylamide.

Particularly suitable monomer ranges for the particulate water-soluble anionic polymer include for instance from 1 to 60%, preferably from 5 to 55%, more preferably from 10 to 50%, more preferably still from 15 to 45%, particularly from 20 to 40%, by weight of water-soluble ethylenically unsaturated anionic monomer, preferably acrylic acid or salts thereof such as sodium acrylate; and from 40 to 99%, preferably from 45 to 95%, more preferably from 50% to 90%, more preferably still from 55% to 85%, particularly from 60% to 80%, by weight of water-soluble ethylenically unsaturated non-ionic mon omer, preferably acrylamide or methacrylamide.

The particulate water soluble organic anionic or non-ionic polymer may contain some structuring or branching but preferably is substantially linear. In preparing the particu late water-soluble organic anionic or non-ionic polymer the one or more water-soluble ethylenically unsaturated monomers may be copolymerised with structuring or branch ing agents to provide some degree of structuring in the formed polymers, provided that the amount employed does not render the polymers insoluble and provided that the polymer is substantially water-soluble. Typical structuring or branching agents include methylene bis acrylamide and tetra allyl ammonium chloride. Typically, the amount employed would be less than 500 ppm by weight, often below 200 ppm, usually below 100 ppm, normally below 50 ppm, and suitably below 10 ppm. Preferably the particu late water-soluble organic anionic or non-ionic polymer is prepared in the absence of structuring or branching agents. In the present invention the definition of water-soluble in regard to the water-soluble ethylenically unsaturated anionic or non-ionic monomers means having a solubility in water of at least 5 g monomer in 100 ml_ water at 25°C.

The particulate water-soluble organic anionic or non-ionic polymer may be prepared by any conventional and known methods of polymerisation well-documented in the lit erature and patents.

Preferably, polymerisation is effected by reacting an aqueous solution of the desired monomer or mixture of monomers using redox initiators and/or thermal initiators. Typi cally, redox initiators include a reducing agent, such as sodium sulphite, the sodium metabisulphite, sulphur dioxide and an oxidising compound, such as ammonium per sulphate or a suitable peroxy compound, such as tertiary butyl hydroperoxide etc. re dox initiation may employ up to 10,000 ppm (based on the weight of aqueous mono mer) of each component of the redox couple. Preferably though, each component of the redox couple is often less than 1000 ppm 1 to 100 ppm, normally in the range from 4 to 50 ppm. The ratio of reducing agent to oxidising agent may be from 10:1 to 1 :10, preferably in the range from 5:1 to 1 :5, more preferably from 2:1 to 1 :2, for instance around 1 :1.

The polymerisation of the aqueous monomer or mixture of monomers may be con ducted by employing a thermal initiator alone or in combination with other initiator sys tems, for instance redox initiators. Thermal initiators would include a suitable initiator compound that releases radicals at an elevated temperature, for instance compounds, such as azobisisobutyronitrile (AIBN), 4,4‘-azobis-(4-cyanovaleric acid) (ACVA). Typi cally, thermal initiators are used in an amount of up to 10,000 ppm based on the weight of the aqueous monomer or monomer mixture. In most cases, however, ther mal initiators are used in the range from 100 to 5000 ppm, preferably from 200 to 2000 ppm, more preferably from 300 to 700 ppm, usually around from 400 to 600 ppm, based on the weight of the aqueous monomer or monomer mixture.

The particulate water-soluble organic anionic or non-ionic polymer may be formed by any of the known processes, such as reverse phase suspension polymerisation to yield polymeric beads, reverse-phase emulsion polymerisation to yield reverse-phase emulsions or reverse-phase dispersions, or aqueous dispersion polymerisation to yield aqueous dispersions. Preferably, however, the particulate water-soluble organic ani onic or organic polymer should be formed by an aqueous solution polymerisation, sometimes referred to as gel polymerisation. Such an aqueous solution polymerisation would typically involve polymerising an aqueous solution containing the at least one water-soluble ethylenically unsaturated monomer. This would suitably be carried out in a reactor vessel although other methods may be employed for example polymerising the aqueous solution on a moving belt.

Such a reactor vessel may be a batch type vessel or preferably a tubular type vessel with an inlet at one end into which the aqueous monomer solution enters and an outlet at the other end from which a formed polymer gel emerges. Such a tubular type vessel may have inwardly sloping walls so as to take the shape of a truncated cone or frus tum. It may also be desirable to combine such a vessel with a pre-polymerisation ves sel which would comprise an inlet for receiving the aqueous monomer solution, a sec tion within which the aqueous monomer partially polymerising as and an outlet for de livering the partially polymerised monomer into the tubular reactor. Such a system and method for using it is described in EP 2900698. Desirably, the aqueous solution of at least one water-soluble monomer should have a concentration typically in the range of from 10 to 50% by weight of monomer based on the total weight of the aqueous solu tion and preferably from 15 to 40% by weight, more preferably from 20 to 35% by weight, and more preferably still from 25 to 30% by weight. The polymerisation initia tion system would desirably be according to the description in the paragraphs above.

The polymer gel formed from this aqueous solution polymerisation should desirably be cut into smaller pieces, dried and ground into a powder. Cutting the polymer gel into smaller pieces may be achieved by any typical commercial sized cutting, comminuting or mincing apparatus. Typically, these gel pieces may range in size from 1 mm to 100 mm, typically from 1 mm to 20 mm and often in the range from 5 mm to 15 mm or from 5 to 10 mm. The gel pieces can then be dried at an elevated temperature, for instance by passing the gel pieces under direct heat or in a chamber at an elevated tempera ture to enable the gel pieces to form substantially dry polymer pieces. The gel pieces may be dried in an atmosphere at a temperature of at least 100°C, for instance in the range of from 100°C to 130°C, for instance from 105°C to 120°C, typically from 110°C to 115°C. The dry polymer pieces would then desirably be ground into a powder.

Thus, in one desired form of the invention the particulate water-soluble organic anionic or non-ionic polymer which is a ground powder is obtainable by aqueous solution polymerisation to form a polymer gel which is cut, dried and ground. Alternatively, the particulate water-soluble organic anionic or non-ionic polymer which is a ground pow der may be obtained by grinding the polymer in the form of beads, for instance beads that have been prepared by a reverse-phase suspension polymerisation process. Nev ertheless, it is preferred that the ground powder is obtained by the aforementioned aqueous solution polymerisation to form a polymer gel.

The inventors have found that particulate water-soluble organic anionic or non-ionic polymer in the form of a ground powder and prepared by aqueous solution polymeri sation to provide a polymer gel which is cut, dried and then ground yields a product which integrates into the mineral particles easily to yield a pressure agglomerate of im proved characteristics. Without being limited to theory this may be as a result of the particular particle size distribution of this particular polymer product form or the physi cal form of the ground powdered polymer particles.

The inventors have found that in accordance with the present invention the particulate water-soluble organic polymers of a particular particle size are more effective at inte grating with the mineral particles. The particulate water-soluble organic polymers should have a particle size of at least 90% by weight below 425 pm. The particulate water-soluble organic polymers may have a particle size of at least 90% by weight be low 400 pm, for instance at least 90% by weight below 350 pm. Desirably the particu late water-soluble organic polymers may have a particle size of at least 90% by weight below 300 pm, preferably at least 90% by weight below 250 pm and more preferably at least 90% by weight below 220 pm and still more preferably at least 90% by weight below 212 pm. There is no particular minimum particle size for the particulate water- soluble organic polymers but such polymers in the size range of at least 90% by weight from 50 pm to below 425 pm, for instance at least 90% by weight from 50 pm to below 400 mih have been found to be suitable. Generally, the particulate water-solu ble organic polymers would tend not to have particle sizes of at least 90% by weight below 50 pm due to the handleability of dry polymer particles of such small sizes. Suit ably, the particulate water-soluble organic polymers have a particle size of at least 90% by weight from 100 pm to below 400 pm, suitably at least 90% by weight from 100 pm to below 300 pm, preferably at least 90% by weight from 100 pm to below 250 pm and more preferably at least 30% by weight from 100 pm to 220 pm and still more preferably at least 90% by weight from 100 pm to 212 pm. Another possible range of particle size lies at least 90% by weight from 300 pm to 400 pm. This has been found to be particularly suitable in the formation of pressure agglomerates containing coal fines for strengths after 20 hours. A further desirable particle size range lies in the range at least 90% by weight below 200 pm when forming pressure agglomerates containing coal fines for longer periods, for instance greater than 20 hours and nor mally at least 48 hours. The optimum range in terms of overall strength when making pressure agglomerates containing coal fines often lies in the size range of at least 90% by weight from 200 to 300 pm. Another desirable size range lies in the range at least 90% by weight from 200 to 400 pm and this has been particularly suitable for overall strength when making pressure agglomerates containing ferroalloy particles.

Providing the water-soluble organic polymer particles within a particular size range may be provided by using a filtering means using one or more suitable filter mem branes to provide a particle size distribution within the required range and removing particles which fall outside the required range. Alternatively, the desired particle size may be provided by producing the particulate polymer under certain conditions, for in stance by cutting polymer gels formed by solution polymerisation, then drying and then grinding.

Preferably, however, the production of the water-soluble organic polymer particles within a desired size range may be provided using a classifier mill. Such a classifier mill may include, for example a Zirkoplex-Sichtermuhle.

A typical method for providing the water-soluble organic polymer particles within a de sired size range may employ a cyclone classifier and/or a trommel. Suitably such a cyclone classifier and/or trommel may typically separate particles of the water-soluble organic polymer particles within the desired particle size range from those that are not.

Suitably a feed material containing the water-soluble organic polymer may be con veyed using a dosing screw into a grinding chamber. Such water-soluble organic poly mer may typically have been prepared by an aqueous solution polymerisation process to produce a polymer gel and dried to produce dried polymeric fragments. Such water- soluble organic polymer, e.g. the dried polymeric fragments, once introduced into the grinding chamber would typically fall and be impacted by a rotating grinding element, which may comprise small metal tubes mounted on a rotor plate. The water-soluble organic polymer may impact the rotating grinding element at a velocity of at least 5 m/s.

The ground polymer particles so formed in the grinding chamber may typically consist of a wide range of particle sizes from larger sized coarse particles to smaller sized fine particles. The ground polymer particles should desirably be captured and conveyed, for instance by an upward moving gas flow, typically air flow, and transported to a classifier trommel. Polymer particles with the correct size would follow the gas flow through the turning wheel to a downstream cyclone classifier. Coarse particles falling outside the correct size range would be rejected by the trommel and kept into the mill ing chamber until they reached the maximum size allowed by the rotating trommel.

The desired particle size distribution may be provided by varying speed of the mill and classifier as well as by the amount of gas flow.

The particle size can be analysed using a test sieve comprising a metal wire cloth, for instance conforming to DIN Iso 3310-1.

Automatic particle size analysers, for instance the Mastersizer 3000, may also be con veniently used for analysing the particle size of the polymeric water-soluble organic polymer particles. A further suitable method for establishing the particle size range of a particular sample would employ the Malvern sizer which employs a laser diffraction technique.

The particulate water-soluble organic anionic or non-ionic polymer may also include as small amount of polymer particles which may fall outside these ranges provided that the polymer particles are predominantly within the aforementioned size ranges. Typi cally, up to 10% by weight of the particulate product may fall outside these ranges. Preferably the particulate water-soluble organic polymer is should have a particle size of at least 92 % by weight, preferably at least 95% by weight, below 425 pm, prefera bly below 400 pm. Desirably the particulate water-soluble organic polymers may have a particle size of at least 92 % by weight, preferably at least 95% by weight, below 300 pm, preferably at least 92 % by weight, preferably at least 95% by weight, below 250 pm and more preferably at least 92 % by weight, more preferably at least 95% by weight, below 220 pm and still more preferably at least 92 % by weight, still more pref erably at least 92 % by weight, below 212 pm. Desirably, such polymers may be the size range of at least 92 % by weight, preferably at least 95% by weight, from 50 pm to below 400 pm. Generally, at least 92 % by weight, preferably at least 95% by weight, of the particulate water-soluble organic polymers would tend not to have parti cle sizes of below 50 pm due to the handleability of dry polymer particles of such small sizes.

Suitably, the particulate water-soluble organic polymers have a particle size of at least 92 % by weight, preferably at least 95% by weight, from 100 pm to below 400 pm, suitably at least 92 % by weight, preferably at least 95% by weight, from 100 pm to be low 300 pm, preferably at least 92 % by weight, preferably at least 95% by weight, from 100 pm to below 250 pm and more preferably at least 92 % by weight, preferably at least 95% by weight, from 100 pm to 220 pm and still more preferably at least 92 % by weight, preferably at least 95% by weight, from 100 pm to 212 pm.

The particulate water-soluble organic anionic or non-ionic polymer should have an in trinsic viscosity of from 8 to 30 dl/g. Preferably, the intrinsic viscosity should be from 10 to 30 dl/g, more preferably more 12 to 25 dl/g, most preferably from 15 to 25 dl/g. Intrinsic viscosity of the water-soluble organic anionic or non-ionic polymer may be de termined by first preparing a stock solution. This may be achieved by placing 1 .0 g of the polymer in a bottle and adding 199 ml of deionised water. This mixture may then be mixed for 4 hours, for instance on a tumble wheel, at ambient temperature (25°C). Diluted solutions may then be prepared by, for instance, taking 0.0 g, 4.0 g, 8.0 g, 12.0 g and 16.0 g, respectively, of the aforementioned stock solution and placing each into 100 ml volumetric flasks. In each case, 50 ml of sodium chloride solution (2M) should then be added by pipette and a flask then filled to the 100 ml Mark with deionised wa ter and in each case the mixture is shaken for 5 minutes until homogenous. In each case, the respective diluted polymer solutions are in turn transferred to an Ubbelohde viscometer and the measurement carried out at 25°C with the capillary viscometer Lauda iVisc. As such, the reduced specific viscosity of each of the diluted solutions may be calculated and then extrapolated to determine the intrinsic viscosity of the pol ymer, as described in the literature.

The water-soluble organic anionic or non-ionic polymer should be water-soluble. By water-soluble we mean that the polymer has a gel content measurement of less than 50% by weight gel. The gel content measurement is described below.

The gel content may be determined by filtering a stock solution (preparation of a stock solution is described above in the method of measuring intrinsic viscosity) through a sieve with a 190 pm mesh size. The residue which stays in the filter is washed, recov ered, dried (110°C) and weighed, and the percentage of undissolved polymer is calcu lated (weight of dry residue from the filter [g] /weight of dry polymer before filtration [g]). Where necessary, this provides a quantifiable confirmation of visual solubility evaluation.

The pressure agglomerate may comprise the binder in an amount of from 0.1 to 2.5 weight %, based on the total weight of the pressure agglomerate. Suitably, the amount of binder may be from 0.5 to 2.0 weight %, based on the total weight of the pressure agglomerate. Desirably, the pressure agglomerate may comprise mineral particles present in an amount of from 97.5 to 99.9 weight % and the binder in an amount of from 0.1 to 2.5 weight %, based on the total weight of the pressure agglomerate. Preferably, the pres sure agglomerate may comprise the mineral particles in an amount from 98.0 to 99.5 weight % and the binder in an amount from 0.5 to 2.0 weight %, based on the total weight of the pressure agglomerate.

In accordance with the present invention the binder product used in making the pres sure agglomerate desirably should be predominantly or entirely the particulate water- soluble organic anionic or non-ionic polymer. Preferably the greater than 80% by weight, preferably at least 90% by weight and more preferably at least 97% by weight of the binder component of the pressure agglomerate is formed from the binder prod uct which is the particulate water-soluble organic anionic or non-ionic polymer, based on the total weight of the binder.

Preferably, the pressure agglomerate of the present invention is selected from the group consisting of a briquette and an extrudate. Typically, the briquette may be in the form of a compressed block of any shape, including a sphere, rectangle, square, rod, strip, broken strip, sheet or broken sheet. Typically, the extrudate may take the form of an elongated article having a cross-sectional shape of the die through which it has been extruded. Therefore, a die with a circular shape would produce an extrudate with a circular cross-section.

In the presently claimed invention, preferably the longitudinal direction of extension is preferably the maximum extension of the briquette. The traversal direction of exten sion is preferably the maximum extension of the briquette orthogonal (perpendicular) to the longitudinal direction of extension. Typically, the longitudinal direction of exten sion is longer than the traversal direction of extension. In this case the briquette would have a longitudinal axis being substantially longer than its transversal axis if it exhibits an oblong shape.

In the presently claimed invention, preferably 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 width corresponds to the transversal direction of extension of the gunwale to the length and all the gunwale to the width (Cartesian space). Preferably, the length of the briquette is in the range of from 1 to 10 cm, more preferably in the range of from 2 to 8 cm, most preferably in the range of from 2 to 4 cm. Preferably, the height of the briquette is in the range of from 0.5 to 6 cm, more preferably in the range of from 1 to 5 cm, most preferably in the range of from 1 to 2 cm. Preferably the width of the briquette is in the range of from 1 to 10 cm, more preferably in the range of from 2 to 8 cm, most preferably in the range of 2 to 4 cm.

In the process step (a) of manufacturing the pressure agglomerate typically a mixture of the mineral particles, water and the binder product is first formed. In general, the mineral particles may already contain sufficient water for the formation of the pressure agglomerate. However, additional water may be added if the mineral particles do not contain sufficient water. The binder product should be thoroughly integrated with the mineral particles to provide a mixture with a relatively uniform composition. This may be achieved by mixing the mineral particles, binder and water in a suitable mixer, for instance an Eirich mixer, for at least 30 seconds and up to 30 minutes before transfer ring the mixture to the pressure of agglomeration apparatus.

Preferably the mineral particles or the mixture containing the mineral particles, water and binder product should have a water content in the range of from 5 to 50 weight %, preferably from 5 to 45 weight %, more preferably from 10 to 40 weight % and more preferably still from 10 to 20 weight %, based on the total weight of mineral particles, determined according to standard gravimetric techniques, for instance determination of water content.

In step (b) briquettes may be produced by feeding the mixture of mineral particles, binder product and water to a briquetting apparatus and formed into a block. The bri quetting apparatus is preferably a briquetting apparatus that includes briquetting roll ers. The mixture is fed to the briquetting rollers. The rollers compress the mixture. One or more of the rollers prefer of the 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 should be dried for a suitable period of time. Desirably the drying period may be from 12 to 48 hours, preferably for a period of from 18 to 36 hours.

The detailed description of step (a) of the process described above may also be used for making extrudates.

In general, the process of extrusion in step (b) of the process requires feeding the mix ture of mineral particles, binder product and water through a die plate or other extru sion orifice. Typically, the extrusion apparatus comprises an inlet through which the mixture of mineral particles, binder product and water are fed. Suitably, once in the ex trusion apparatus a rotating screw feed within a housing, which is driven by a drive mechanism, feeds the mixture along its length towards a die plate at the end of the screw feed. Usually the die plate consists of a multiplicity of orifices through which the extruded material exits the apparatus. The action of the screw feed within the housing may also serve to further mix and integrate the mineral particles, binder product and water. The action of the screw feed on the mixture causes significant compression as the mixture is forced against the die plate and squeezed through the orifices to form an extrudate.

The extrudate should be dried and this may be achieved according to the description 4 step (c) given above.

The pressure required to form the pressure agglomerates of the present invention is generally quite significant. Preferably the pressure should be at least 4.9 mega pas cals (MPa), corresponding to an applied pressure of 50 kg force/cm². In general, the pressure may be greater than this, for instance at least 7.5 MPa, such as at least 10 MPa, and in some cases at least 20 MPa. Some pressure agglomerates, for instance extrudates in some cases, require even greater pressures, for instance at least 30 MPa or at least 40 MPa and in some cases at least 50 MPa. The invention is illustrated by the following examples.

Examples

SUBSTRATES

Coal Fines

Sample was a blended sample of coal as received from an Indian operation.

Particle size was reduced to <1 mm. Initial moisture was 4.5%. Added moisture was 10%

Ferro Alloy

Sample was as received from customer and used as supplied.

Moisture was 4.4%. Added moisture was 8%

Binders

Binders were used as supplied

TEST METHOD

1 . 500g of the substrate to be briquetted was weighed in a beaker and transferred to a mixer bowl.

2. The appropriate dose of binder as indicated in the results tables was added as a solid and the contents mixed for 2 minutes at a mid-range speed using a planetary mixer to homogenize.

3. Water was added to bring the total moisture to the target value and the material mixed for a further 5 minutes.

4. The mixture was charged in to a briquetting machine roller feed moving at 3.5rpm with a screw feed of 64rpm under 30KN pressure.

5. The briquettes formed were collected. Dust and broken briquettes were discarded.

6. ‘Green Test’ strengths of 6 briquettes per batch were measured within 2 minutes of the briquette formation, using a Chatillon digital force gauge. The average force for breakage and the RSD were calculated.

7. The remainder of the briquettes were placed in a tray at ambient temperature.

8. After approximately 24hr, 48hr, 72hr and any other times as recorded in the results tables, a further 5 or 6 briquettes were removed from the tray and the force to break them re-measured using the Chatillon gauge. Averages and variation were calculated. COAL FINES TEST RESULTS

All products have 30% by weight sodium acrylate (NaAc) and 70% by weight acryla mide (ACM). IV = Intrinsic viscosity

All strength results are the average of 5-6x briquette tests are illustrated in the Fig ures.

Table 1 - General particle size classification for water-soluble organic polymer

The particle size range of the products tested if indicated as coarse, medium or fine would be as indicated in Table 1 or as the range quoted in the respective tables 2-7 either as a range or mixed ranges denoted by the codes:

# Mixed particle size: 72% below QOOmiti to 300 pm; 17% below 300 pm; and re- mainder above 600 pm;

[] Mixed particle size: 40% below 600pm to 300 pm; 11% below 300pm; and remain der above 600 pm; {} Mixed particle size: 76% below 600pm to 300 pm; 18% below 300pm; and remain der above 600 pm

Polymer particles with the stated particle sizes were provided by sieving the whole particulate polymeric product through ISO 3310-1 compliant sieves.

Table 2 - Green strength of briquettes at zero hours

Table 3 - Strength of briquettes at 20 hours

Table 4 - Strength of briquettes at 48 hours

Table 5 - Strength of briquettes at 72 hours

Table 6 - Strength of briquettes at 120 hours

Table 7 - Strength of briquettes at 168 hours

FERRO ALLOY TEST RESULTS

Both polymers have 30% by weight sodium acrylate (NaAc) content and 70% by weight acrylamide (ACM).

The particle size is as indicated in the tables 8-10 either by stated range or as mixed ranges denoted by the codes the meaning of which are shown below.

# Mixed particle size: 72% below 600pm to 300 pm;17% below 300 pm; and remain- der above 600 pm

// Mixed particle size: 32% below 600pm to 300 pm; 10% below 300pm; and remain der above 600 pm Table 8

able 9

31

able 10

EXPLANATION FOR COAL FINES RESULTS Green Tests

Results 1 -30 and Figure 1 show that immediately after briquettes are formed (green strength) the Fine (<212 micron) binders give higher strength than the Medium (425miti>c>300miti) binders which give higher strength than the Coarse (>600 micron) binders for all ranges of molecular weight evaluated (i.e. binders prepared with IV’s of 15, 18 and 24)

Where the particulates have been prepared by %passing fractionation, the <300micron binders at all molecular weights give higher compression strength than the <400micron binders, which give higher compression strength than the Mixed grade binders (see de scriptions of particle size range of the Mixed binders in test Ref# 22, 25, 28).

These results indicate that within a few minutes of contact with the ore, the smaller the particulate size of the binder down to a size of around <300micron, the stronger the com pression strength of the briquette. The <300 micron products gave the highest compres sion strength of the different sizes evaluated and suggests this is the optimum sizing for green strength.

Strength with Age

Briquettes were stored at ambient temperature and re-measured periodically. See results 31 -162 and Figures 2-6.

Results continued to show a consistent ‘strength v particle size’ relationship throughout with Fines always stronger than Medium which was always stronger than Coarse.

After 20hrs the <400micron and <300micron tests form the optimum range.

After longer curing periods the <200 micron samples are optimum.

In terms of product IV the relationship with strength gain is not as strong as it is for the particle size variation, all three products perform relatively similarly at each time. The higher IV products (IV 24 and 18) show their peak strength between 48-72hrs, whereas the lower IV product reaches peak later at 72-120 hours. All briquettes were seen to drop in strength by the end of the testing period 168hr. Conclusions

There is a strong relationship that is replicated on every occasion between particle size and strength gain. Fine particulates of the size 200-300micron consistently outperform medium particulates which consistently outperform coarse particulates.

The optimum size range depends on the IV of the product and the age at which the bri quettes require their maximum strength.

EXPLANATION FOR FERRO ALLOY RESULTS

Results are shown for two different product types (IV 18, which was the same product type as for the Coal Tests, and a further water-soluble product having an IV in the range of from 8 to 30. Each was tested as a Mixed grain size (see test Ref 163 and 179 for descriptions) and compared against a finer <400micron version.

These tests were done on different days by different people compared with to the Coal Tests

Green Strenath (Dav 0)

Results 163-192 show consistently that when compared at equivalent doses the Mixed coarser grade results have a significantly lower strength than the <400 fines results. (For each dosage comparison the <400 fines tests are coloured slightly grey in the table for ease of comparison with the white Mixed tests above them).

Strenath With Aae (Dav 1 and Dav 5)

Again, a consistent pattern is seen with every Mixed test giving lower strength results than every dose-comparable Fines test.

OVERALL CONCLUSIONS

Multiple tests with 7 different products on two different substrates have shown on every occasion that the finer grade binder products give higher strengths than the equivalent coarser grade binder products.

The optimum performance in these tests is from binders have a maximum particle size of around 200-400 micron.

Claims

1. A pressure agglomerate comprising

A) mineral particles; and

B) a binder in which the binder is formed from a binder product, which binder product com prises a particulate water-soluble organic anionic or non-ionic polymer of one or more water-soluble ethylenically unsaturated monomers and which water-soluble organic anionic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g, wherein the particulate water-soluble organic anionic or non-ionic polymer has a particle size of at least 90% by weight below 425 pm, in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder.

2. A pressure agglomerate according to claim 1 in which the mineral particles are selected from the group consisting of coal fines, iron ore fines, particulate millscale, particulate nickel ore, particulate chromium ore and particulate ferroal loys.

3. A pressure agglomerate according to claim 1 or claim 2 in which the mineral particles have a particle size of less than 1 centimetre.

4. A pressure agglomerate according to any one preceding claim in which the min eral particles comprise coal fines which comprise at least 50 wt. -% coal particles passing Tyler Mesh 16 sieve (1 mm sieve opening).

5. A pressure agglomerate according to any one preceding claim in which the min eral particles comprise coal fines which have an ash content of up to 40 wt.-% determined according to standard gravimetric methods.

6. A pressure agglomerate according to any one preceding claim in which the par ticulate water-soluble organic polymer is formed from (meth) acrylamide and op tionally at least one ethylenically unsaturated monomer bearing one or more car boxylic acid groups or sulphonic acid groups or salts thereof.

7. A pressure agglomerate according to any one preceding claim in which the par ticulate water-soluble organic polymer formed from (meth) acrylamide and (meth) acrylic acid or salts thereof.

8. A pressure agglomerate according to any one preceding claim in which the par ticulate water-soluble organic polymer is a copolymer of acrylamide and sodium acrylate.

9. A pressure agglomerate according to any one preceding claim in which the par ticulate water-soluble organic polymer is obtainable by aqueous solution polymerisation to provide a gel which is cut and dried.

10. A pressure agglomerate according to any one proceeding claim in which the particulate water-soluble organic polymer has a particle size of at least 90% by weight below 300 pm, preferably at least 90% by weight below 250 pm and more preferably at least 90% by weight below 220 pm and more preferably still at least 90% by weight below 212 pm.

11. A pressure agglomerate according to any one proceeding claim in which the particulate water-soluble organic polymer has an intrinsic viscosity of from 12 to 25 dl/g.

12. A pressure agglomerates according to any one preceding claim in which the par ticulate water-soluble organic polymer has been obtained by grinding the dried gel obtained from a solution polymerisation of an aqueous solution of the one or more water-soluble ethylenically unsaturated monomers.

13. A pressure agglomerate according to any one preceding claim in which the par ticulate water-soluble organic polymer is present in an amount of from 0.1 to 2.5 wt.-% based on the total weight of the pressure agglomerate.

14. A pressure agglomerate according to any one preceding claim in which the min eral particles are present in an amount of from 97.5 to 99.9 wt.-%, and the partic ulate water-soluble organic polymer is present in an amount of from 0.1 to 2.5 wt.-% based on the total weight of the pressure agglomerate.

15. A pressure agglomerate according to any one preceding claim in which the binder contains greater than 80% by weight, preferably at least 90% by weight, more preferably at least 97% by weight, the particulate water-soluble organic ani onic or non-ionic polymer by total weight of the binder.

16. A pressure agglomerate according to any one preceding claim which is selected from the group consisting of a briquette and an extrudate.

17. A process of manufacturing a pressure agglomerate that comprises:

A) mineral particles; and

B) a binder, which process comprises the steps of: a) mixing the mineral particles, water and a binder product that comprises partic ulate water-soluble organic polymer to obtain a mixture; b) forming the mixture obtained according to step a) into a block or cylinder; and c) drying the block or cylinder obtained according to step b) to obtain the pres sure agglomerate, in which the particulate water-soluble organic polymer is formed from one or more water- soluble ethylenically unsaturated monomers and which water-soluble organic ani onic or non-ionic polymer has an intrinsic viscosity of from 8 to 30 dl/g, wherein the particulate water-soluble organic anionic or non-ionic polymer has a particle size of at least 90% by weight below 425 pm, in which the particulate water-soluble organic anionic or non-ionic polymer is a ground powder.

18. A process according to claim 17, wherein the mineral particles in step a) have a water content in the range of from 5 wt.-% to 50 wt.-%, preferably 5 wt.-% to 20 wt.-% based on the total weight of the mineral particles, determined according to standard gravimetric techniques.

19. A process according to claim 17 or claim 18, wherein the forming step b) is achieved by compression in a shaped container.

20. A process according to any one of claims 17 to 19, wherein the forming step b) is achieved by compression in a press, rollers or by extrusion.

21. A process according to any one of claims 17 to 20, wherein the pressure ag glomerate contains any of the features of claims 2 to 16.

22. A pressure agglomerate comprising

A) mineral particles; and

B) a binder which pressure agglomerate is obtainable from the process of any of claims 17 to 21.

23. Use of a binder product comprising a particulate water-soluble organic anionic or non-ionic polymer of one or more water-soluble ethylenically unsaturated mon omers and which water-soluble organic anionic or non-ionic polymer has an in trinsic viscosity of from 8 to 30 dl/g and having a particle size of at least 90% by weight below 425 pm and in which the water-soluble organic anionic or non-ionic polymer is a ground powder for the manufacture pressure agglomerates contain ing mineral particles.