A method for the production of iron oxide

Abstract

The present invention relates to a method for the production of iron oxide. The present invention also relates to a composition comprising iron oxide and to the use thereof. An object of the present invention is to develop a method for the production of iron oxide wherein the balance between Fe3O4, magnetite, and Fe2O3, hematite, in the final composition of iron oxide particles can be controlled.

Description

[0001] Title: A method for the production of iron oxide

[0002] Description:

[0003] The present invention relates to a method for the production of iron oxide. The present invention also relates to a composition comprising iron oxide and to the use thereof.

[0004] Iron oxides are chemical compounds composed of iron and oxygen. Iron oxides feature as ferrous (Fe(ll)) or ferric (Fe(lll)) or both. Mixed oxides of Fe(ll) and Fe(lll) are FesC also known as magnetite and oxides of Fe(lll) are a-FezOs, also known as hematite, and y-FezOs, also known as maghemite. Iron oxides are used as precursors in iron metal and its many alloys. Other applications of iron oxides are as catalysts in several chemical processes and as pigments, coming in a variety of colours, e.g. black, red, and yellow.

[0005] Methods for the production of iron oxide are well known in the art.

[0006] International application WO 2023 / 191619 in the name of the present applicant relates to a burner process for iron fuel combustion, comprising the steps of providing an iron fuel suspension medium comprising iron fuel, introducing the iron fuel suspension medium into an iron fuel burner arrangement, introducing air from air inlet means into the iron fuel burner arrangement, mixing the iron fuel suspension medium with air for obtaining a combustible medium in the burner arrangement, and igniting the combustible medium to provide a combusting iron fuel containing medium.

[0007] In addition, International application WO 2023 / 121465 in the name of the present applicant relates to a method for producing iron fuel from metal oxide containing charge materials via reducing the metal oxide containing charge materials, comprising the steps of feeding metal oxide containing charge materials to a fluidized bed unit, reducing the metal oxide containing charge materials by flowing a reduction gas through the fluidized bed unit, and removing a stream containing iron fuel from the fluidized bed unit.

[0008] US 5,244,494 relates to a process for the thermal conversion of iron ore to magnetic gamma hematite, which comprises the steps of preheating an iron ore concentrate feed to effect oxidation of magnetite therein to hematite, reducing hematite contained in the oxidized concentrate to magnetite, cooling the reduced concentrate to a lower temperature, oxidizing magnetite in the cooled charge to magnetic gamma hematite.

[0009] JP 2016-129880 discloses an apparatus for producing inorganic spheroidized particles used in producing inorganic spheroidized particles, and a method for producing inorganic spheroidized particles. Such inorganic spheroidized particles are used in fillers for electronic parts in order to enhance the packing efficiency. The apparatus includes a vertical furnace main body located below a disposition position of a cylindrical vertical furnace main body, a plurality of shut-off air introduction portions disposed on a side wall portion of the vertical furnace main body, and a plurality of shut-off air introduction portions. Such a furnace includes a conveying air introducing part for introducing conveying air for conveying the generated first and second inorganic spheroidized particles, and the first raw material. A first flame heats and melts the inorganic powder. A first burner disposed at the top of the vertical furnace main body produces the first inorganic spheroidized particles having a first average particle diameter and spouting metal powder as a second raw material. A second flame heats and melts the metal powder. A first end of the vertical furnace main body is disposed in the air introduction portion for transfer, and the metal powder is oxidized by the outer flame of the second flame so that the formed tip is accommodated in the vertical furnace main body. Such a first burner disposed at the top of the vertical furnace body generates the first inorganic spherical particles having a first average particle size. A second burner includes a second raw material ejection hole for ejecting a metal powder as a second raw material, which is disposed within the conveying air introduction section so that a tip of a second flame for heating and melting the metal powder is formed is contained within the vertical furnace body, and which oxidizes the metal powder with an outer flame of the second flame to generate the second inorganic spherical particles having a second average particle size smaller than the first average particle size. The first average particle size is several pm to several tens of pm, and the second average particle size is 1 pm or less. JP 2016- 129880 does not relate to a method in which the iron oxide thus formed is fed to a process in which iron oxide is converted into iron via a reduction step.

[0010] JP H11-139827 relates to a dry manufacturing method of spherical magnetite powder suitable for a magnetic carrier used in a two component magnetic brush method in electronic copying. According to such a method amorphous sponge iron powder is melted and oxidized in a gas fuel combustion flame to be spheroidized, and then brought into contact with a cooling gas to cool it and then collected by a powder collector. The combustion flame is a combustion flame of propane gas and oxygen or oxygen-enriched air, wherein the supply amount of oxygen is 5 to 8 times the supply amount of propane gas. Such combustion flame produces a high amount of CO2.The spherical magnetite powder thus produced in the combustion furnace is accompanied by the carrying air introduced from the carrying air introducing section and is fed from the powder carrying route to a cyclone and a bag filter of a powder collecting apparatus. Coarse particles are separated at the bottom of the combustion furnace, and fine particles are collected by a bag filter. JP H11-139827 does not relate to a method in which the iron oxide thus formed is fed to a process in which iron oxide is converted into iron via a reduction step.

[0011] Iron fuel is a very promising fuel in which energy is stored in the iron powder when and where needed. In the right conditions, iron powder is flammable and has the property that when the iron powder is contact with oxygen, i.e. burned, a lot of energy is released in the form of heat, without CC>2-emissions and lower NOx-emissions than alternative fuels. This heat can then be converted into hot water, steam, or electricity for use in any kind of application or industry. Another important property of iron powder is that only rust remains during combustion, while no CO2 is released during the combustion of the iron powder. The rust, as a product, can be collected and converted back into the iron powder in a sustainable manner, which makes it a fully circular process.

[0012] An object of the present invention is to develop a method for the production of iron oxide in which a coarse fraction of iron oxide and a fine fraction of iron oxide are obtained, wherein in an embodiment at least one fraction is subjected to one or more process steps to control the final composition thereof, e.g. in terms of particle size distribution and / or amount of FesC and Fe2Os.

[0013] An object of the present invention is to develop a method for the production of iron oxide wherein the balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be controlled.

[0014] Another object of the present invention is to develop a method for the production of iron oxide wherein the iron oxide is used as a feed stock for a reduction process. Another object of the present invention is to a run a method for the production of iron oxide in such a way that the iron fuel boiler is able to separate rust powder with a specific particle size or multiple specific particle sizes.

[0015] Another object of the present invention is to develop a method for the production of iron oxide wherein the formation of CO2 is reduced to a minimum.

[0016] The present invention thus relates to a method for the production of iron oxide comprising preparing a mixture of iron (1) and air (2), igniting the mixture (4) in the presence of air (3) thereby creating a self sustaining CO2 low flame, indirect water cooling the mixture (11) thus ignited and separating in a first step the mixture thus cooled into a solid stream rich in a coarse fraction of iron oxide and a gaseous effluent comprising a fine fraction of iron oxide, wherein the gaseous effluent comprising a fine fraction of iron oxide is separated in a second step into a gas stream depleted from a fine fraction of iron oxide and a solid stream rich in a fine fraction of iron oxide.

[0017] The inventors found that on basis of the above method one or more objects are achieved. According to the present method the burner ignites the powder, which causes it to rise above the ignition temperature and self-ignite. This means that a little amount of energy is added by means of gas combustion to force this self-ignition process. In, the present method is carried out in one single burner and no second powder flow is added. The cooling step is carried out with indirect cooling with water thereby producing steam. Such steam can be used for other processes, e.g. heat recovery.

[0018] Commonly used methods for measuring the particle size distribution of a sample are sieve analysis, laser diffraction, dynamic light scattering and image analysis. The term “coarse fraction” in the present description refers to a particle size distribution D10 of 10 pm, preferably 45 pm, more preferably 60 pm. D10 is a so-called percentile value, i.e. a statistical parameter that can be read directly from the cumulative particle size distribution. D10 is the particle diameter at which 10% of the sample's total mass is composed of particles with diameters smaller than this value. In other words, it is the size below which 10% of all particles are found. The term “fine fraction” in the present description refers to a particle size distribution that is smaller than the afore mentioned coarse fraction. In a sieve analysis the coarse fraction is the fraction that does not pass the specific sieve. The present inventors found that that the separation in the first step is an essential technical feature of the present method because coarse particles may lead to wear of the process equipment used in the second separation step, especially cyclones and filters.

[0019] In an embodiment the present inventors found that for obtaining a combustible medium in the burner arrangement an overall oxygen-to-fuel equivalence ratio is between 0.9 and 2.5 and more preferably between 1.2 and 1.8. Such ratio is obtained by mixing the iron fuel suspension medium with air. The balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be influenced by a specific design of the burner arrangement. The present inventors found that the overall oxygen-to-fuel equivalence ratio in the burner arrangement may influence the balance between Fe3O4, magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles.

[0020] In an example of the present method the gaseous effluent comprising a fine fraction of iron oxide is cooled before the second step of separation is carried out, thereby producing a cooled gaseous effluent. The temperature during the combustion stage can be as high as at least 1200 °C. The energy present in that gaseous effluent can be used in other process steps and therefore a recovery of the heat makes sense. In addition, the equipment used in the second separation step can not withstand high temperatures. Examples of process units to be used in the second step of separation are one or more cyclones and filters. Several cyclone separators can operate in parallel and in series, or a combination thereof, and such a system is known as a multicyclone.

[0021] The present inventors found that in a multicyclone system several grades of solid streams containing fine fractions of iron oxide can be obtained by varying the amount of gas stream supplied to a specific cyclone. The amount of gas stream supplied to a specific cyclone determines the so-called cut-off diameter of the cyclone. The cut-off diameter defines a specific size of the particles that are separated from the gaseous flow entering the cyclone. Thus, in a multicyclone system, i.e. a system of several cyclones positioned in series or parallel, several fine fractions of iron oxide having a specific particle size distribution can be obtained.

[0022] On basis of the above, the present inventors found that the cut-off diameter of the cyclone can be controlled by varying the amount of gas stream supplied, for example an air stream. More admixture of a gas stream results in a lower cut-off diameter; the cyclone will therefore separate more efficiently, and vice versa. By doing this, the particle size distribution of iron oxide can be controlled by controlling the amount of admixture air. In this way, the value of several grades of solid streams containing fine fractions of iron oxide can be maximized.

[0023] One benefit of such a multicyclone system is that when the process for the production of iron oxide, wherein a mixture of iron and air is ignited in the presence of air, is carried out with different grades of iron, for example different particle size distributions, the properties of the fine fraction of iron oxide thus produced can be controlled. In addition, the conditions in the ignition step may be variable which may have an effect on the particle size distribution of the iron oxide coming from the burner. And by using a multicyclone system several grades of solid streams containing fine fractions of iron oxide can be obtained by varying the amount of gas stream supplied to a specific cyclone. Moreover, the multicyclone system enables the production of a high quality solid stream rich in a specific fine fraction of iron oxide as a stream to a reduction process, i.e. a reduction process as disclosed in International application WO 2023 / 121465 in the name of the present applicant. One of the aspects of such a reduction process is the particle size distribution of the iron oxide, i.e. a narrow particle size distribution is preferable wherein only a few very small and / or a few very large particles are present. According to the present method it is now possible to better control the lower limit of the particle size distribution.

[0024] In an embodiment multiple cyclones are placed in series with different diameters resulting in specific separation degrees, i.e. cut-off diameter, for collecting different streams containing iron oxide having a specific particle size distribution. According to such an example each stream having its own specific and adjustable cutoff diameter is stored in a collection tank, thereby maximizing the value of the iron oxide.

[0025] Cooling the gaseous effluent can take place by transporting the gaseous effluent through a tube provided with an outer jacket in which a heat transfer medium is present. Such a heat transfer medium can be used a primary heat source for other processes, such as a boiler. An example of such heat transfer medium is water. The steam thus produced can be used for other processes. In an example a thermal oil can be used as a heat transfer medium. The step of cooling the gaseous effluent comprising a fine fraction of iron oxide may influence the balance between FesC , magnetite, and Fe20s, hematite, in the final composition of iron oxide particles, e.g. the cooling rate thereof.

[0026] In an example, the gaseous effluent comprising a fine fraction of iron oxide is contacted with a gas stream comprising air during the step of cooling. By contacting a fine fraction of iron oxide with an oxygen containing gas stream the balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be influenced. The present inventors found that the more oxygen is contacted with the iron oxide particles, the more Fe2Os, hematite, will be formed.

[0027] In an example the step of cooling comprises a two step process, i.e. a first step of indirect cooling with water and a second step of contacting the gaseous stream with a gas stream comprising air.

[0028] In an example, in the second step of separation the cooled gaseous effluent rich in a fine fraction of iron oxide is contacted with a gas stream comprising air. By contacting a fine fraction of iron oxide with an oxygen containing gas stream the balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be influenced. The present inventors found that the more oxygen is contacted with the iron oxide particles, the more Fe2Os, hematite, will be formed.

[0029] In an example, in the first step of separation the stream comprising iron oxide is contacted with a gas stream comprising air. By contacting the stream comprising iron oxide with an oxygen containing gas stream the balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be influenced.

[0030] In an example, after the ignition stage the ignited mixture of air and iron oxide is cooled and during the step of cooling the mixture is contacted with a gas stream comprising air. By contacting the ignited mixture of air and iron oxide with an oxygen containing gas stream the balance between FesC , magnetite, and Fe2Os, hematite, in the final composition of iron oxide particles can be influenced.

[0031] Cooling the ignited mixture of air and iron oxide can take place by transporting the ignited mixture of air and iron oxide through a tube provided with an outer jacket in which a heat transfer medium is present. Such a heat transfer medium can be used for heat recovery. In an example, the solid stream rich in a fine fraction of iron oxide is subjected to one or more additional steps, chosen from the group of milling, sieving, drying, and aerating step, thereby producing iron oxide particles having a specific particle size distribution and iron oxide particles having a specific chemical configuration, e.g. mixed oxides of Fe(ll) and Fe(lll), such as FesC (magnetite) and Fe2Os (hematite). Drying is done for obtaining iron oxide particles having a specific content of water.

[0032] In another example, the solid stream rich in a fine fraction of iron oxide is sent to a reduction process, e.g. a reduction process as disclosed in the afore mentioned discussed International application WO 2023 / 121465 in the name of the present applicant.

[0033] In an example, the solid stream rich in a coarse fraction of iron oxide is cooled thereby producing a cooled solid stream rich in a coarse fraction of iron oxide. Cooling the solid stream rich in a coarse fraction of iron oxide can take place by transporting the solid stream rich in a coarse fraction of iron oxide through a tube provided with an outer jacket in which a heat transfer medium is present. Such a heat transfer medium can be used for heat recovery.

[0034] In another example the solid stream rich in a fine fraction of iron oxide can be combined with the solid stream rich in a coarse fraction of iron oxide. The combined stream can be subsequently cooled.

[0035] After the step of cooling, the cooled solid stream rich in a coarse fraction of iron oxide, or the stream obtained after combining the solid stream rich in a fine fraction of iron oxide and the solid stream rich in a coarse fraction of iron oxide, is subjected to one or more additional steps, chosen from the group of milling, sieving, drying and aerating step, thereby producing iron oxide particles having a specific particle size distribution and iron oxide particles having a specific chemical configuration, e.g. mixed oxides of Fe(ll) and Fe(lll), such as FesC (magnetite) and Fe2Os (hematite). Drying is done for obtaining iron oxide particles having a specific content of water.

[0036] In an example, the cooled solid stream rich in a coarse fraction of iron oxide is sent to a reduction process, e.g. a reduction process as disclosed in the afore mentioned discussed International application WO 2023 / 121465 in the name of the present applicant.

[0037] The present invention also relates to a composition comprising iron oxide obtained according to a method as discussed above, wherein the amount of Fe2Os is at least 60 wt.%, preferably at least 80 wt.% and more preferably at least 95 wt.%, on basis of the total weight of the composition.

[0038] The present invention also relates to a composition comprising iron oxide obtained according to a method as discussed above, wherein the amount of FesC is at least 60 wt.%, preferably at least 80 wt.% and more preferably at least 95 wt.%, on basis of the total weight of the composition.

[0039] The present invention also relates to a composition comprising iron oxide obtained according to a method as discussed above, wherein for Fe2Os and FesC the sieve residue 45pm is at most 1 , preferably at most 0,5 and at least 0,01 , preferably at least 0,1.

[0040] The present invention also relates to a composition comprising iron oxide obtained according to a method as discussed above, wherein for Fe2Os and FesC the sieve residue 325pm is less than 0,05 %, preferably less than 0,04 %, more preferably less than 0,02%.

[0041] The present invention also relates to the use of composition as discussed above as a pigment for manufacturing any one of coatings, paints, primer coatings, cement compositions, and construction materials.

[0042] The drawing schematically illustrate an example of a method according to the present invention. The present method is not restricted to the specific example disclosed here.

[0043] The sole Figure discloses a schematic process flow diagram of a method according to the present invention.

[0044] Iron fuel 1 and air 2 are sent to a suspension generator for preparing a mixture 4 of iron fuel and air. Mixture 4 is sent to a burner arrangement, for example a burner arrangement as disclosed in International application WO 2023 / 191619 in the name of the present applicant. The burner arrangement can be supplied with a gas stream 3, e.g. a gas stream comprising air or enriched flue gas recirculation, or a combination thereof. Although not shown in the sole figure, the same applies for the suspension generator. After the ignited stage a combusted mixture 11 is obtained. Mixture 11 is sent to a cooling unit. The cooling process can be assisted optionally by contacting combusted mixture 11 with a gas stream 18 comprising air, e.g. a gas stream comprising air or enriched flue gas recirculation, or a combination thereof. The cooled mixture 13 thus obtained is sent to first separation stage, resulting in a solid stream 6 rich in a coarse fraction of iron oxide and a gaseous effluent 8 comprising a fine fraction of iron oxide. According to an embodiment, the first separation stage can be carried out in such a way that stream 13 comprising iron oxide is contacted with a gas stream 5 comprising air. Gas stream 5 can also originate from enriched flue gas recirculation, or even in combination with a gas stream comprising air. The temperature of gaseous effluent 8 is further reduced in another cooling unit resulting in a cooled gaseous effluent 10 comprising a fine fraction of iron oxide. The cooling process can be assisted optionally by contacting gaseous effluent 8 with a gas stream 17 comprising air. Gas stream 17 can also originate from enriched flue gas recirculation, or even in combination with a gas stream comprising air. Cooled gaseous effluent 10 comprising a fine fraction of iron oxide is separated in a second step into a gas stream 12 depleted from a fine fraction of iron oxide and a solid stream 14 rich in a fine fraction of iron oxide. Second step may comprise a series of cyclones (not shown here), each having its own specific cut-off diameter. Solid stream 14 rich in a fine fraction of iron oxide may thus consist of a series of solid streams rich in a fine fraction of iron oxide, wherein each solid stream reflects a specific particle size distribution of iron oxide.

[0045] During the second separation stage cooled gaseous effluent 10 is contacted with a gas stream 9 comprising air resulting in gas stream 12 and solid stream 14. Gas stream 9 can also originate from enriched flue gas recirculation, or in combination with a gas stream comprising air. Gas stream 12, i.e. flue gas, can be sent to other process units, such as filter units, before release thereof to the environment takes place.

[0046] Solid stream 14 rich in a fine fraction of iron oxide can be used for different routes. A first option is to subject solid stream 14 rich in a fine fraction of iron oxide as a stream 21 to one or more additional steps, chosen from the group of milling, sieving, drying, and aerating step, thereby producing iron oxide particles 15 having a particle size distribution D10 of less than 60 pm, preferably less than 45 pm, more preferably less than 10 pm. A second option is to send solid stream 14 rich in a fine fraction of iron oxide as a stream 20 to a reduction process, i.e. a reduction process as disclosed in International application WO 2023 / 121465 in the name of the present applicant. A third option is to further cool solid stream 14 rich in a fine fraction of iron oxide and send solid stream 14 as a stream 19 a to cooling unit. It is to be noted that the aforementioned three options, i.e. first option, second option and third option, can take place simultaneously, but in some embodiments only the first option applies, or a combination of the first and third option applies etc. However, the present method is not restricted to any specific option.

[0047] Solid stream 6, rich in a coarse fraction of iron oxide, and coming from the first separation stage is sent to a cooling unit thereby producing a cooled solid stream 7 rich in a coarse fraction of iron oxide. As discussed above, solid stream 6 and solid stream 19 can be combined and the combined stream can be cooled, resulting in stream 7. Stream 7 can follow two different routes, i.e. stream 7 is subjected to one or more additional steps, chosen from the group of milling, sieving, drying, and aerating step. According to another route, stream 7 is sent to a reduction process, i.e. a reduction process as disclosed in International application WO 2023 / 121465 in the name of the present applicant.

[0048] The iron oxide particles produced with the method according to the present invention can be used as a component for topcoats. The preferred particle size for such application as topcoat is 0,05 - 2 pm, preferably 0,1 - 1 pm. For a red coloured topcoat the amount of Fe2Os is > 95 wt.%, for a black coloured topcoat the amount of FesC is > 92 wt.%. The sieve residue on 45 pm mesh is in a range of 0,005 - 1 %, preferably 0,01- 0,5%.

[0049] The iron oxide particles produced with the method according to the present invention can be used in cement and concrete compositions. For red coloured cement and concrete compositions the amount of Fe2Os is > 95 wt.%, for black coloured cement and concrete compositions the amount of FesC is > 92 wt.%. The sieve residue 45 pm mesh is in a range of 0,005 - 1 %, preferably 0,01- 0,5%.

[0050] The iron oxide particles produced with the method according to the present invention can be used in primer coatings as well. For red coloured primer coatings the amount of Fe2Os is > 70 wt.%, for black coloured primer coatings the amount of FesC is > 77 wt.%. The sieve residue on 325um mesh is less than 0,1 %, preferably less than 0,02%.

[0051] The iron oxide particles produced with the method according to the present invention can be used in toner compositions. The preferred particle size for such application is < 1 pm. The amount of FesOdn a toner composition is about >96 wt.%. The iron oxide particles produced with the method according to the present invention can be used in batteries. The preferred particle size for such application is

[0052] < 1 pm. The amount of FesC in a toner composition is about >99 wt.%.

[0053] The iron oxide particles produced with the method according to the present invention can be used in catalyst composition for the water-gas shift reaction (WGSR) in which carbon monoxide and water vapor are reacted to form carbon dioxide and hydrogen. The preferred particle size for both Fe2Os and FesC in such application is

[0054] < 75 pm.

Claims

CLAIMS1. A method for the production of iron oxide comprising preparing a mixture of iron (1) and air (2), igniting the mixture (4) in the presence of air (3) thereby creating a self sustaining CO2 low flame, indirect water cooling the mixture (11) thus ignited and separating in a first step the mixture (13) thus cooled into a solid stream (6) rich in a coarse fraction of iron oxide and a gaseous effluent (8) comprising a fine fraction of iron oxide, wherein the gaseous effluent (8) comprising a fine fraction of iron oxide is separated in a second step into a gas stream (12) depleted from a fine fraction of iron oxide and a solid stream (14) rich in a fine fraction of iron oxide.

2. A method according to claim 1 , wherein the gaseous effluent (8) comprising a fine fraction of iron oxide is cooled before the second step of separation is carried out, thereby producing a cooled gaseous effluent (10).

3. A method according to claim 2, wherein during the step of cooling the gaseous effluent (8) comprising a fine fraction of iron oxide is contacted with a gas stream (17) comprising air.

4. A method according to any one or more of the preceding claims, wherein in the second step of separation the cooled gaseous effluent (10) rich in a fine fraction of iron oxide contacted with a gas stream (9) comprising air.

5. A method according to any one or more of the preceding claims, wherein in the first step of separation the stream comprising iron oxide (13) is contacted with a gas stream (5) comprising air.

6. A method according to any one or more of the preceding claims, wherein during the step of cooling the mixture (11) thus ignited is contacted with a gas stream (18) comprising air.

7. A method according to any one or more of the preceding claims, wherein the solid stream (14) rich in a fine fraction of iron oxide is subjected as a stream (21) to one or more additional steps, chosen from the group of milling, sieving, drying, and aerating step.

8. A method according to any one or more of the preceding claims, wherein the solid stream (14) rich in a fine fraction of iron oxide as a stream (20) is sent to a reduction process.

9. A method according to any one or more of the preceding claims, wherein the solid stream (6) rich in a coarse fraction of iron oxide is cooled thereby producing a cooled solid stream (7) rich in a coarse fraction of iron oxide.

10. A method according to claim 9, wherein the solid stream (14) rich in a fine fraction of iron oxide is subjected as a stream (19) to a cooling step, together with solid stream (6) rich in a coarse fraction of iron oxide.

11. A method according to any one or more of the preceding claims, wherein the cooled solid stream (7) rich in a coarse fraction of iron oxide is subjected to one or more additional steps, chosen from the group of milling, sieving, drying, and aerating step.

12. A method according to any one or more of the preceding claims, wherein the cooled solid stream (7) rich in a coarse fraction of iron oxide is sent to a reduction process.

13. A composition (15, 16) comprising iron oxide obtained according to a method according to any one or more of claims 1-12, wherein the amount of Fe2Os is at least 60 wt.%, preferably at least 80 wt.% and more preferably at least 95 wt.%, on basis of the total weight of the composition.

14. A composition (15, 16) comprising iron oxide obtained according to a method according to any one or more of claims 1-12, wherein the amount of FesC is at least 60 wt.%, preferably at least 80 wt.% and more preferably at least 95 wt.%, on basis of the total weight of the composition.

15. A composition (15, 16) comprising iron oxide obtained according to a method according to any one or more of claims 1-12, wherein for Fe2Os and FesC the sieve residue 325pm is less than 0,05 %, preferably less than 0,04 %, more preferably less than 0,02%.

16. A composition (15, 16) comprising iron oxide obtained according to a method according to any one or more of claims 1-12, wherein for Fe2Os and FesC the sieve residue 45pm is at most 1 , preferably at most 0,5 and at least 0,01 , preferably at least 0, 1.

17. The use of composition according to any one or more of claims 13-16 as a pigment for manufacturing any one of coatings, paints, primer coatings, cement compositions, and construction materials.

18. A topcoat comprising iron oxide particles having a particle size of 0,05 - 2 pm, preferably 0,1 - 1 pm, wherein the 45 pm mesh sieve residue of the iron oxide particles is in a range of 0,005 - 1 %, preferably 0,01- 0,5%.

19. A cement composition comprising iron oxide particles, wherein the 45 pm mesh sieve residue of the iron oxide particles is in a range of 0,005 - 1 %, preferably 0,01 -0,5%.

20. A primer coating comprising iron oxide particles, wherein the 325um mesh sieve residue on a 325um mesh of the iron oxide particles is less than 0,1 %, preferably less than 0,02%.

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