EA042651B1 - METHOD FOR FINE GRINDING OF IRON ORE OR IRON ORE PRODUCTS UNDER NATURAL HUMIDITY - Google Patents

Description

The field of technology to which the invention belongs

The present invention relates to methods for finely grinding iron ore or iron ore products at natural moisture content. In particular, this invention relates to methods for finely grinding iron ore containing an amount of water naturally present in it when extracted from an ore deposit, or iron ore products (iron ore concentrate, sinter, among others), leading to improved results in relation to both the method as well as in relation to the environment.

State of the art

The fine grinding method refers to grinding the material to be processed in order to reduce the particle size distribution.

The device for fine grinding can be described by combining the operation of one or more nodes. Such devices are usually large scale equipment capable of processing thousands of tons of ore per day.

Fine grinding of iron ore is currently carried out mainly in two ways: wet processing and dry processing.

The present invention provides a novel and patentable method for finely grinding iron ore or iron ore products: natural moisture processing. The natural moisture fine grinding according to the present invention is suitable for processing raw iron ore or ore products (iron ore concentrate, sinter, etc.) with moisture up to 12% by weight.

Natural moisture in mineral processing typically occurs during mining operations, which involve subjecting ore from a mine to sieving and crushing. From now on, the process will be carried out wet, with added water, or dry, through a drying step, for the ore sent to subsequent processing steps.

Fine grinding to small sizes (where the product has a particle size of less than 1 mm) requires the use of classifying equipment, to separate fine fractions (desired product) from coarse fractions, where the coarse fractions must be regrind in a closed circuit.

The concentration of iron ore, after the stages of crushing, grinding and classification in the processing of ore, is indicated in the document BR 102015003408-3. The apparatus claimed in this patent, although made dry, aims at concentrating iron ore through a combination of magnetic roller separators, air classifiers, cyclones and bag filters. Also, the device in BR 102015003408-3 works with materials containing 2 to 3% residual moisture.

The main difficulty in performing the crushing, grinding and classifying steps at natural moisture is to produce a product with a particle size of less than 16 mm, since conventional sieves are not able to carry out this procedure effectively, and therefore the specifications for product size distribution are not guaranteed. . In addition, operational results such as blockage of screens due to moisture are common.

For this reason, the present pulverizing processes are either completely wet or completely dry.

Dry and wet processing.

Iron ore naturally has, on average, 5 to 12% of its weight of water in its composition. This natural moisture makes the ore viscous or highly cohesive, making it difficult to process.

Dry processing involves the removal of water from the ore through a drying step, which may be carried out, for example, by means of dryers maintaining a residual water content in the ore of less than 1% by weight.

Fig. 1 represents a process for beneficiation of wet iron ore (ROM - raw ore deposit) commonly used in the prior art. In wet processing, after the crushing and screening step, large amounts of water are added to the ore.

The next step in relation to crushing and screening is called grinding. This operation is designed to increase the grinding and adjust the particle size of the ore to the desired size. Usually, this operation is carried out in conjunction with the stage of classification, separation of particles by size, using hydrocyclones or sieves.

The wet grinding step is usually, but not limited to, carried out in ball mills or vertical mills with high electricity and water consumption.

The process flow for the wet processing of iron ore products (iron ore concentrate, sinter, among others) in this prior art can be seen in FIG. 2. It should be noted that two grinding stages and an intermediate filtration stage are required.

In the dry processing of iron ore (ROM (Raw Ore Deposit)) before grinding, a drying step takes place, which consumes a large amount of fuel used to heat

- 1 042651 drying air. In addition, the drying step requires large means to remove suspended ultra-fine particles (dust) formed during the processing and movement of the ore.

Dry grinding is usually combined with static and/or dynamic classifiers. Commonly used grinding equipment is ball mills, which, as already mentioned, consume a large amount of electricity. Fig. 3 shows an iron ore beneficiation process commonly used in the prior art.

The process flow for dry processing of iron ore products (iron ore concentrate, sinter, etc.) in the present state of the art can be seen in FIG. 4.

Problems posed in the prior art in the field of iron ore fine grinding processes.

Conventional fine grinding processes for ores and iron ore products use large amounts of water in their processing and/or large amounts of energy and fuel for the drying step.

The environmental impact and environmental responsibility generated by conventional iron ore processing plants is significant due to the amount of water consumed, the loss of ultrafine iron ore particles, the formation of combustion residues and particulate emissions (when drying is required), and high energy consumption, in addition to other things.

Vertical Roll Mill, Roll Press, Roll Crusher and High Speed Screeners

In some grinding equipment commonly used in the cement and coal industries, such as vertical roller mill (VRM), roller press (high pressure grinding rollers, HPGR) and roller crusher (RC), materials are fed at their natural moisture content. Vertical Roll Mill (VRM) is commonly used for grinding materials such as coal, lignite, limestone, clay, clinker.

The vertical roller mill (VRM) consists of a turntable and rolls that are located on it and which move due to the rotation of the table. The material is introduced into the center and moved to the edges and crushed in this part by rollers. They are connected to a hydraulic system which changes the roller pressure as needed for the finer particle size of the material. After fine grinding, the particles are removed by means of an updraft of air which can be heated, drying the ore at the same time as it is sent to the dynamic classifier, where particles below the desired size are discharged from the mill and the coarse particles are returned to the table for grinding. This equipment, therefore, is part of the completely dry processing, the main application of which is in the cement industry. It is also possible to operate by overflow, without the need for air to move the material and without dynamic classification. To do so, however, it must be done in natural humidity or have a drying step before it.

The roller press (HPGR) is usually used before or after the ore grinding stage as an auxiliary grinding stage. This equipment consists of a pair of counter-rotating rolls supported on a rigid frame. The material to be ground is fed into the top of the equipment between the rolls, and the compression of this layer of particles is performed in holes that are larger than the maximum particle size in the starting material. Thus, the size reduction is created by interparticle grinding. The roller press has a higher energy efficiency compared to conventional grinders and mills (eg ball mill) because structural grinding of material particles is performed with reduced energy loss in terms of heating and screening.

The roller crusher (RC) is generally used in the ore crushing stage of the auxiliary fine grinding stage. The equipment consists of rollers that rotate in opposite directions and the principle of operation is the crushing of particles between the rollers. A thin layer of ore is fed into the equipment and the rolls are simultaneously in contact with the particles. The performance of rolls with an opening smaller than the largest particle size is controlled by the desired maximum particle size of the product. For example, if a product with a maximum particle size of 1 mm is required, the device will have its openings set at or slightly below this value.

High acceleration screens (greater than 10 g, where g is gravity acceleration) have a high acceleration vibrating screen system that promotes the effect of releasing ore on the screen, which prevents blockage, and also provides a greater opportunity for the ore to be sorted/separated. In this invention, no water is sprayed onto the ore in the sieves used.

It is important to note that high acceleration sieves and vertical roller mills (VRMs) have never been used in iron ore grinding/screening applications. In addition, roller crushers (RC) have never been used for fine grinding (less than 1 mm).

OBJECT AND ADVANTAGES OF THE INVENTION

The object of the present invention is to provide an efficient fine grinding process for iron ore or iron ore products (iron ore concentrate, agglomerate, among others) at natural moisture, with moisture up to 12% of its mass, without the need

- 2 042651 adding water or including a drying step in the process in a technically feasible and economically viable manner. The present invention focuses on the fine grinding of raw iron ore or iron ore products, with the use and placement of equipment improved in processing materials with very different chemical and physical properties, such as coal, lignite, limestone, clay and clinker.

It is a further object to provide an efficient process for fine grinding of raw iron ore or iron ore products (iron ore concentrate, sinter, etc.) at natural moisture content up to 12% of its mass to produce a product with a particle size of less than 16 mm. in the case of fine grinding of raw iron ore, and less than 0.074 mm in the case of materials from iron ore products (iron ore agglomerate or concentrate to be crushed to a size suitable for granulation).

The fine grinding process routes of this invention have important advantages in that they are both industrial and environmentally beneficial:

abstaining from the use of water in the grinding process, reducing the environmental impact either by not consuming this natural resource or by reducing the flow to be disposed of in tailings;

refraining from the use of energy and fuels necessary for the drying process of the material;

increased efficiency in the processing of iron ore and iron ore products, through reductions in: energy consumption, equipment size, equipment commissioning costs, operating costs;

great ease of operation;

reduced retention and replacement of worn materials used in the processing of raw iron ore and iron ore products compared to fully wetted and fully dry process routes;

reduction of ancillary activities such as replacement of grinding media in ball mills (wet and dry);

reducing the loss of ultra-fine iron ore;

refraining from a system or circuit for removing airborne ultra-fine particles (dust) generated by processing and handling of the ore, since the natural moisture of the ore is present in the suspension of these particles.

The essence of the invention

In order to achieve the above objects, the present invention provides process routes for fine grinding of iron ore or iron ore products at natural moisture content, i.e. without the need to add water or a drying step to the process.

This invention consists of processing routes that combine grinding and classifying equipment for a more efficient fine grinding process, such equipment is: a roller press (HPGR), a vertical roller mill (VRM), a roller crusher (RC) and a sieve with a high acceleration on at least 10 g.

Thus, the present invention is directed to a process for fine grinding of iron ore, carried out at natural moisture, either from material coming directly from an ore deposit (ROM (Raw Ore Deposit)) or from already processed iron ore products (iron ore concentrate, sinter, among other things). ), where the processing is applied with at least one of the following equipment: a vertical roller mill (VRM), a roller press (HPGR), a roller crusher (RC) and a screen with a high acceleration of at least 10 g. For iron ore applications, the vertical roller mill (VRM) will operate with weir flow and the option to dry the ore during grinding will not apply.

Brief description of the drawings

The detailed description below refers to the attached figures, among which:

fig. 1 illustrates the beneficiation of wet iron ore (ROM (Raw Ore Deposit)) according to the state of the art;

fig. 2 illustrates a wet beneficiation process for iron ore products (iron ore concentrate, sinter, among others) according to the state of the art;

fig. 3 illustrates the beneficiation process of dry iron ore (ROM (Raw Ore Deposit)) according to the state of the art;

fig. 4 illustrates a dry beneficiation process for iron ore products (iron ore concentrate, sinter, among others) according to the state of the art;

fig. 5 illustrates the beneficiation of raw iron ore or iron ore products at natural moisture, in accordance with the present invention;

fig. 6 shows nine processing routes according to the present invention.

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Description of preferred embodiments of the invention

The following detailed description is not intended to limit the scope, applicability, or configuration of the present invention in any way. Namely, the description below provides the understanding needed to implement the exemplary embodiments. In applying the teachings of the present invention, those skilled in the art will recognize various suitable alternatives that may be employed without departing from the scope of the present invention.

As will be apparent to any person skilled in the art, this invention is directed to fine grinding in an iron ore beneficiation process, without addressing any other steps such as, for example, concentration. However, the present invention is not limited to such particular embodiments.

Fig. 1 shows a state-of-the-art wet iron ore (ROM) process comprising crushing 101, screening 102, grinding 103 and concentrating 104 steps. , it is carried out in a closed loop by means of a screening step 102, which can be carried out, for example, on vibrating screens. The grinding step 103 requires the addition of a significant amount of water. The ore concentration step 104 may be performed by gravity, magnetic, flotation, and the like.

Fig. 2 shows a state-of-the-art process for beneficiation of wet iron ore products (iron ore concentrate, sinter, etc.) where the fine grinding process comprises a first grinding stage 201, a filtration stage 202 due to high material moisture, and a second grinding stage 203. After fine grinding , the material is subjected to the granulation step 204 to obtain the desired end product, which in this case is iron ore granules.

Fig. 3 shows a state of the art process for beneficiation of dry iron ore (ROM—Raw Ore Deposit) comprising the steps of crushing 301, screening 302, drying 303, grinding 304, and concentrating 305. The crushing step 301 may be performed at various stages (eg, primary crushing to quaternary crushing), it is carried out in a closed cycle by means of a screening step 302, which can be performed, for example, on vibrating screens. Drying 303 can be performed by itself in the grinding equipment by means of hot air flowing from burners and blowers. Concentration 305 can be done by gravity, magnetic, electrostatic, etc.

Fig. 4 shows a state-of-the-art process for beneficiation of a dry iron ore product (iron ore concentrate, agglomerate, among others), where the fine grinding process comprises a drying step 401, a first grinding step 402, and a second grinding step 403. After fine grinding, the material is subjected to granulation steps 404 to obtain the desired end product, which in this case is iron ore pellets.

The description below will be directed to (9) nine possible process routes for fine grinding of the present invention. Process routes are applicable for two possible sources of iron ore: 1) the first source of material coming directly from the ore deposit (ROM (Raw Ore Deposit)), and 2) the second source of iron ore products already processed in the beneficiation processing (iron ore concentrate, sinter etc.) before being introduced into the treatment according to the invention.

This invention, illustrated in a simplified manner by means of FIG. 5 is a beneficiation process where the fine grinding process 501 is carried out entirely at natural moisture, either from material coming directly from an ore deposit (ROM (Raw Ore Deposit)) at up to 12% moisture by weight, or from already processed iron ore products (concentrate iron ore, sinter, etc.), also at up to 12% moisture After fine grinding 501, the final product may be ground iron ore itself, or the steps of concentration 502, granulation 503, or agglomeration 504 may be performed according to with the desired end product.

processing routes according to this invention are illustrated in detail in FIG. 6 and consist of:

path 1: the fine grinding process 501, at natural moisture, occurs initially in a roller press (HPGR) for up to three stages and then is carried out as a secondary treatment in a vertical roller mill (VRM) for up to three successive stages;

path 2: the fine grinding process 501, at natural moisture, occurs initially in a vertical roller mill (VRM) for up to three stages, and then is carried out as a secondary treatment in a roller press (HPGR) for up to three successive stages;

route 3: fine grinding process 501, at natural moisture, takes place in a roller press (HPGR) and is connected in a closed circuit with a high acceleration screen (at at least 10 g),

- 4 042651 where the coarse product (retained material) will be sent back to the roller press (HPGR) and the fine product (pass through material) is the end product of fine grinding;

route 4: the 501 fine grinding process, at natural moisture, takes place in a vertical roller mill (VRM) and is connected in a closed circuit with a high acceleration screen (at at least 10 g), where the coarse product (retained material) will be redirected to the vertical roller mill (VRM), and the fine product (passing material) is the end product of fine grinding;

route 5: 501 fine grinding process, at natural moisture, starts in a roller press (HPGR), the material continues to be processed in a vertical roller mill (VRM), and then it is classified in a high acceleration sieve (at least 10 g), where the coarse the product (retained material) is returned to the roller press (HPGR) to complete the cycle, and the fine product (through material) is the end product of fine grinding;

route 6: 501 fine grinding process, at natural moisture, starts in a vertical roller mill (VRM), the material continues to be processed in a roller press (HPGR), and then it is classified in a high acceleration sieve (at least 10 g), where the coarse the product (retained material) is returned to the vertical roller mill (VRM), completing the cycle, and the fine product (passing material) is the end product of fine grinding;

process route 7: in the 501 fine grinding process, under natural moisture, the material is classified by means of a high acceleration sieve (at least 10 g), and its fine product (passing material) is processed by means of a roller press (HPGR) or a vertical mill (VRM) over up to three stages. The output product consists of a fine product, which is the final product of fine grinding; and coarse material (retained material) is also considered a product insofar as it is traded in this way (agglomerate);

process route 8: the fine grinding process 501, at natural moisture, takes place in a roller crusher (RC) and can be performed in several stages in the sequence of applied fine grinding equipment with two or more rows of rollers; and process route 9: the fine grinding process 501, at natural moisture, starts at the roller crusher (RC), and can be carried out in several stages when applied in succession of fine grinding equipment with double rollers or more, and then the material is classified in a sieve with high acceleration (at least 10 g), where the coarse product (retained material) is returned to the roller crusher (RC), completing the cycle, and the fine product (passing material) consists of the final product.

Tests have shown that the invention produces products with a range of particle sizes less than 16 mm, particle sizes less than 8 mm, particle sizes up to 99.8% of material passing through a 1 mm sieve, and between 60 to 85% material in a sieve with a hole size of 0.074 mm.

Example 1

Pilot scale high acceleration screen tests were performed using iron ore with about 50% through material at 1 mm, 11% moisture and very high loss on ignition (LOI) (about 10%), which is typical of a bonded material that is difficult to screen in natural moisture. The sub-size recovery at 1.0 mm screen size is in the range of 35 to 41%, according to the amount of fine particles of the present example, which shows screening efficiency at natural humidity even for such a cohesive material. Tab. 1a, 1b and 1c show the chemical analysis, the particle size distribution of the test sample and the distribution of particles below and above the size obtained in control tests, as well as the mass balance of the test.

Table 1a

Chemical analysis Chemical analysis (%)

Fe _SiO2 R A1 ₂ 0z MP TiO ₂ CaO MgO LOI 57.0 6.23 0.196 1.610 0.263 0.104 0.023 0.112 9.99

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Table 1b

Particle size distribution in high acceleration sieve tests Trial 1 Trial 2 Particle Size Distribution Particle Size Distribution Size (%) Material, (%) Material, Material, holes initial Material, Not initial Not (mm) th having passed having passed having passed th th through having passed th through material sieve th through material sieve th through sieve sieve 40000 100.00 100.00 100.00 100.00 100.00 100.00 31500 98.04 100.00 96.69 98.38 100.00 97.50 25000 96.38 100.00 93.89 97.79 100.00 96.59 19000 92.17 100.00 86.79 95.07 100.00 92.40 16000 90.09 100.00 83.27 92.63 100.00 88.64 12500 86.11 100.00 76.57 88.87 100.00 82.84 10000 82.59 100.00 70.62 85.43 100.00 77.54 8000 79.09 100.00 64.72 82.21 100.00 72.57 6300 75.60 100.00 58.83 78.23 100.00 66.44 2400 57.07 99.27 28.05 57.64 99.50 34.97 1000 48.37 88.05 21.09 47.01 86.52 25.62 840 47.30 85.75 20.86 45.75 83.34 25.40 710 45.93 82.71 20.64 44.22 79.48 25.12 500 43.42 77.12 20.25 41.58 72.67 24.74 210 37.50 64.55 18.90 35.58 58.24 23.31 150 34.83 59.25 18.04 33.11 53.11 22.28 106 32.20 54.09 17.14 31.06 49.34 21.17 74 31.54 52.92 16.84 29.16 44.80 20.69 45 26.16 43.86 14.00 24.90 38.04 17.78 37 23.77 39.36 13.05 23.32 35.60 16.66 25 18.69 30.06 10.87 19.70 30.13 14.05 15 12.93 19.95 8.10 15.00 23.15 10.59 10 9.40 14.00 6.24 11.72 18.26 8.17

Table 1c

Mass balance when tested with a sieve with high acceleration % on

Consumption % by mass Consumption mass original original 100.00 100.00 material material Test Material, Material, Trial 2 1 past 40.70 past 35.10 through a sieve through a sieve material, not material, not past 59.30 past 64.90 through a sieve through a sieve

Example 2

Tests were performed on high pressure grinder (HPGR) and the test results are presented in table. 2. After two treatments performed in the same equipment, it was possible to obtain 56% of the material remaining in the 0.074 mm sieve. This indicates a high degree of refinement of fine particles.

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table 2

Particle Size Distribution in High Pressure Grinding Roll Tests (HPGR)

Press feeding 1st pass 2nd pass

Size R (mm) % % individual Batteries dual state-of-the-art % % Wait a minute % Individual hold % Accumulated retention % Wait a minute % Waiting time Individual hold % Hold ania holding nia hold me 3.360 0.39 0.39 99.61 0.02 0.02 99.98 0.01 0.01 99.99 1,000 38.53 38.92 61.08 21.16 21.18 78.82 13.72 13.72 86.28 0.710 4.68 43.60 56.40 5.75 26.93 73.07 4.57 18.29 81.71 0.500 5.13 48.73 51.27 5.55 32.47 67.53 4.59 22.88 77.12 0.420 1.89 50.62 49.38 2.65 35.12 64.88 2.40 25.28 74.72 0.300 5.71 56.33 43.67 6.32 41.45 58.55 6.96 32.24 67.76 0.210 4.18 60.51 39.49 5.00 46.45 53.55 5.37 37.61 62.39 0.150 6.02 66.53 33.47 7.42 53.86 46.14 7.48 45.09 54.91 0.074 7.06 73.59 26.41 9.77 63.63 36.37 11.42 56.50 43.50 0.045 byp 4.33 77.93 22.07 6.18 69.81 30.19 7.30 63.81 36.19 With 22.07 100.00 0.00 30.19 100.00 0.00 36.19 100.00 0.00

Example 3

The tests were performed in a vertical roller mill (VRM), and the results are presented in table. 3. The tests were performed under high and low pressure conditions, 500 psi (3.45 MPa) and 300 psi (2.07 MPa) respectively, and under both conditions, material reduction above 1 mm was possible, which indicates a good degree of particle size reduction in thicker fractions.

Table 3

Particle size distribution in vertical roller mill tests

Size (mm) High pressure - 1 run Low pressure - 2 passes original material Product original material Product 9.525 100.00 100.00 100.00 100.00 6,350 98.72 100.00 100.00 100.00 4,750 96.82 100.00 100.00 100.00 3,350 95.92 100.00 99.90 100.00 2.360 94.80 99.89 99.90 100.00 1,700 94.08 99.78 99.40 99.90 1.180 93.35 99.44 98.70 99.70 0.850 92.79 98.65 94.60 98.80 0.600 92.29 97.75 96.60 97.90 0.425 91.34 96.86 95.80 97.00 0.300 90.89 96.07 95.00 96.10 0.212 89.83 95.12 94.10 95.30 0.150 86.26 93.04 92.10 94.10 0.106 78.99 88.43 89.20 91.90 0.090 71.90 80.97 85.40 89.40 0.075 63.91 76.59 80.70 85.00 0.045 33.41 55.81 56.20 63.90

Example 4

Control tests were performed using a roller crusher (RC) with iron ore with about 43% remaining at 1 mm, and the results are presented in table. 4 show that it is possible to reduce the content of material above 1 mm and provide a high generation of fine particles (less than 0.075 mm). Tests have shown that the roller crusher is effective in size reduction for various initial particle sizes.

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Claims (16)

Table 4 Particle distribution Size Original by test size 1 2 4 with roller 5 crusher 6 (mm) material Run Run Run Runs Runs 1.00 43.68 13.34 3.88 0.36 0.2 0.12 0.500 56.86 25.92 15.39 6.09 3.99 2.00 0.150 79.93 45.12 33.00 28.70 25.43 21.71 0.106 84.40 50.21 37.41 35.75 32.36 28.81 0.075 88.47 53.73 40.31 41.29 37.78 33.25 0.045 56.79 42.70 46.40 42.32 35.99 Numerous variations are allowed within the scope of the protection of this invention. Accordingly, it should be emphasized that the present invention is not limited to the specific configurations/embodiments described above. CLAIM 1. Method for fine grinding of iron ore or iron ore products at natural moisture, characterized in that it includes at least two fine grinding cycles, one performed using at least one equipment selected from the group consisting of a roller press (HPGR), roller crusher (RC) and a high acceleration sieve of at least 10 g, and the other using a vertical roller mill (VRM), while at least two cycles of fine grinding are carried out at natural humidity and are carried out without a moistening or drying step. 2. The method according to claim 1, characterized in that a roller press (HPGR) is used in the first fine grinding cycle, and a vertical roller mill (VRM) is used in succession in the second fine grinding cycle. 3. The method according to claim 1, characterized in that a vertical roller mill (VRM) is used in the first fine grinding cycle, and a roller press (HPGR) is used sequentially in the second fine grinding cycle. 4. The method according to claim 1, characterized in that in the first cycle of fine grinding a vertical roller mill (VRM) is used, and in the second cycle of fine grinding, screening is used, performed in a sieve with a high acceleration of at least 10 g, in a closed circuit. 5. The method according to claim 1, characterized in that the first fine grinding cycle uses a roller press (HPGR), the second fine grinding cycle uses a vertical roller mill (VRM), and the third fine grinding cycle uses high acceleration screening. at least 10 g, in a closed loop. 6. The method according to claim 1, characterized in that in the first cycle of fine grinding a vertical roller mill (VRM) is used, and in the second cycle of fine grinding a roller press (HPGR) is used, and in the third cycle of fine grinding sieving is used in a sieve with high acceleration of at least 10 g, in a closed loop. 7. The method according to claim 1, characterized in that in the first cycle of fine grinding, sieving on a sieve with a high acceleration of at least 10 g is used, and in the second cycle of fine grinding, a vertical roller mill (VRM) is used. 8. The method according to claim 1, characterized in that in at least two cycles of fine grinding, a roller crusher (RC) is used in several stages in succession. 9. The method according to claim 1, characterized in that the first and second fine grinding cycles use a roller crusher (RC) in series, and the third fine grinding cycle uses a screen with high acceleration of at least 10 g in a closed circuit. 10. Method according to claims 8 and 9, characterized in that the roll crusher (RC) has 2, 4, 6, 8 or 10 rolls. 11. The method according to any one of claims 1 to 10, characterized in that the material supplied to the processing consists of iron ore from an ore deposit or iron ore products. 12. Method according to any one of claims 1 to 11, characterized in that the material fed to the treatment has a moisture content of up to 12% by weight. 13. Process according to any one of claims 1 to 12, characterized in that the end product of fine grinding has a particle size of less than 16 mm. 14. The method according to any one of claims 1 to 12, characterized in that the end product of fine grinding has a particle size of less than 8 mm. 15. The method according to any one of claims 1 to 12, characterized in that the end product of fine grinding has a particle size of less than 0.074 mm. 16. The method according to any one of claims 1 to 7, characterized in that the grinding on a roller press (HPGR) or vertical roller mill (VRM) is carried out in up to three stages. -