OA19963A - Comminution process of iron ore or iron ore products at natural moisture. - Google Patents

Abstract

This invention relates to a process of comminution of iron ore or iron ore products (pellet feed, sinter feed, etc.) at natural moisture without the need to add water or to include a drying step in the process, that is technically and economically feasible. The comminution process of this invention uses at least one piece of equipment selected from the group consisting of roller press (HPGR), vertical roller mill (VRM), roller crusher (RC) and high acceleration screen of at least 10G.

Description

TECHNICAL FIELD

[001] This invention relates to processes of comminution of iron ore or iron ore products at natural moisture. More particularly, this invention relates to processes for fine comminution iron ore containing the amount of water naturally présent in it when extracted from the mine, or iron ore products (pellet feed, sinter feed, among others), resulting in important gains for both the process and the environment.

DESCRIPTION OF THE STATE OF THE ART

[002] The comminution process refers to the fragmentation of the processed material to decrease particle size distribution.

[003] A minerai comminution facility can be described by the combination of one or more unit operations. They are usually large-scale facilities capable of processing thousands of tons of ore per day.

[004] Iron ore comminution is currently carried out basically in two ways: wet processing and dry processing.

[005] This invention provides a new and inventive process of comminution of iron ore or iron ore products: processing at natural moisture. This invention’s comminution at natural moisture is suitable for processing raw iron ore or ore products (pellet feed, sinter feed, etc.) with moisture up to 12% of its weight.

[006] Natural moisture of minerai processing typically occurs in mining operations that involve the ore from the pit to screening and crushing it. From this moment on, the process will be carried out wet, with water added, or dryj with a drying step, for the ore to proceed to the subséquent processing steps.

[007] Comminution in fine sizes (where the product has a particle size of less than 1 mm) requires classification equipment to separate fine fractions (desired product) from coàrse fractions, where coarse fractions must be re-grinded in a closed circuit.

[008] Iron ore concentration, subséquent to the crushing, grinding and classification stages in the ore processing, is addressed by document BR 102015003408-3. The System claimed by this patent, despite being made dry, is focused towards iron ore concentration by combining magnetic roller separators, aeroclassifiers, cyclones and bag filters. Also, the System in BR 102015003408-3 opérâtes with materials containing 2 to 3% residual moisture.

[009] The major difficulty of performing the crushing, grinding and classification steps under natural moisture is to produce a product with a particle size of less than 16 mm, as conventional screens are not able to perform this work efficiently and therefore do not guarantee the size distribution spécification of the product. In addition, operational issues such as obstruction of sieve screens due to moisture are quite common. [0010] For this reason, current comminution processes are carried out either completely wet or completely dry.

Dry and wet processing

[0011] Iron ore naturally has, on average, from 5% to 12% of its weight in water in its composition. This natural moisture makes the ore sticky or highly cohesive, which makes its beneficiation difficult.

[0012] Dry processing comprises the removal of water from the ore by means of a drying step which may be carried out, for example, by dryers, maintaining a residual water value in the ore of less than 1% by weight.

[0013] Figure 1 represents the wet iron ore beneficiation process (ROM - Run of mine), commonly used in the state of the art. In wet processing, after the crushing and screening stage, large amounts of water are added to the ore.

[0014] The next step to crushing and screening is called grinding. This operation aims to increase fragmentation and adjust the size of the ore particles to a desired value. Typically, it is an operation carried out in conjunction with a classification step, particle size séparation, using hydrocyclones or screens.

[0015] The wet grinding step is usually, but not limited, performed in bail mills or vertical mills with high consumption of electricity and water. '

[0016] The wet processing route of iron ore products (pellet feed, sinter feed, among others), in the State of the art, can be seen on Figure 2. Note that two grinding steps and an intermediate filtration step are required. ।

[0017] In the dry processing of iron ore (ROM), before grinding, there is a drying step that consumes a large amount of fuel used to heat the drying air. In addition, the drying step requires large facilities for removal of suspended ultrafines (dust) generated in ore processing and handling.

[0018] Dry grinding is usually combined with static and/or dynamic classifiers.

The commonly used grinding equipment is bail mills which, as already mentioned, consume a large amount of electricity. Figure 3 shows the process of dry iron ore beneficiation, commonly used in the State of the art.

[0019] The dry processing route of iron ore products (pellet feed, sinter feed, etc.), in the State of the art, can be viewed by means of Figure 4.

Problems generated by State of the art iron ore comminution processes

[0020] Conventional processes of ore comminution and iron ore products use large amounts of water in their processing and/or energy and fuel for the drying step.

[0021] The environmental impact and liability generated by conventional iron ore processing plants are significant due to the amount of water consumed, loss of iron ore ultrafïnes, génération of combustion residues and particulate émissions (when drying is required), high energy consumption, among others.

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

[0022] On some grinding equipment commonly used in the cernent and coal industry, such as the Vertical Roller Mill (VRM), the Roller Press (High Pressure

Grinding Rolls, HPGR) and the Roller Crusher (RC), materials are fed with their natural moisture. The vertical roller mill (VRM) is commonly applied in grinding materials such as coal, lignite, limestone, clays, clinker.

[0023] The vertical mill (VRM) consists of a tumtable and rollers which are arranged thereon and which move due to the rotation of the table. The material is introduced into the center and moves to the edges and in this path is comminuted by the rollers. These are connected to a hydraulic system that changes roll pressure according to the need for finer particle size material. After comminution, the particles are removed by an upward flow of air thaï can be heated, drying the ore at the same time that it il directed 25 to a dynamic classifier, where particles with particle size below the one desired leave the mill and coarse particles retum to the table to be comminuted. This equipment, therefore, is part of a completely dry processing, its main application being in the cernent industry. It is i also possible to operate by overflow, without the need of air to transport the material and without dynamic classification. To do so, however, it must operate with natural moisture or 30 hâve a drying step prior to it.

[0024] The roller press (HPGR) is generally applied before or after the ore grinding step as an auxiliary grinding step. This equipment consists of a pair of rollers that rotate in opposite directions, supported on a rigid frame. The material to be grinded is fed into the upper part of the equipment between the rollers, and the compression of this particle bed is performed in openings larger than the maximum particle size in the feed. Thus, size réduction is made by interparticular comminution. The roller press has higher energy efficiency compared to conventional crushers and mills (e.g., bail mill) because the structural breakage of the material grains is performed with reduced energy loss in heat and noise.

[0025] The roller crusher (RC) is generally applied in the ore crushing step as an auxiliary comminution step. The equipment consists of rollers that rotate in opposite directions and the working principle is the crushing of particles between the rollers. The equipment is fed with a thin layer of ore and the rollers simultaneously touch the particles. The rollers work with an opening smaller than the largest particle size, regulated by the desired top size. For example, if a product with a 1 mm top size is required, the machine will hâve its opening set to this value or slightly less.

[0026] High accélération screens (greater than 10G, where G is gravitational accélération) hâve a high accélération screen vibration system, promoting an ore release effect on the screen, which prevents its obstruction as well as enabling greater likelihood of ore being sorted/separated. In this invention, no water is sprayed on the ore in the sieves used.

[0027] It is important to note that high accélération screens and vertical roller mills (VRM) hâve never been used in iron ore grinding/screening circuits. In addition, roller crushers (RC) hâve never been used for fine comminutions (less than 1mm).

OBJECTIVE AND ADVANTAG^S OF THE INVENTION ।

[0028] The objective of this invention is to provide an efficient comminution process for iron ore or iron ore products (pellet feed, sinter feed, among others) at natural moisture, with moisture up to 12%' of its weight, without the need to add water or include a

I i drying step in the process, in a technically and economically feasible manner. The focus of the invention is on the comminution of raw iron ore or iron ore products, with use and disposai of equipment employed in the beneficiation of materials with totally different Chemical and physical characteristics, such as coal, lignite, limestone, clay and clinker.

[0029] An additional objective is to provide an efficient process of comminution of raw iron ore or iron ore products (pellet feed, sinter feed, etc.) at natural moisture, with up to 12% of its weight in moisture, to produce a product with a particle size of less than 16 mm in case of raw iron ore comminution and less than 0.074 mm in case of materials from iron ore products (sinter feed or pellet feed to comminute until the feeding size for pelletizing).

[0030] The comminution routes of the présent invention hâve important advantages that benefit both the industrial process and the environment:

— Forgoing the use of water in the grinding process, reducing e nvironmental impacts either by not consuming this natural resource, or by reducing the flow to be disposed in tailings dams;

— Forgoing the use of energy and fuels necessary for the drying process of the material;

— Increased processing efficiency of iron ore and iron ore products, with r éduction in: energy consumption, size of facilities, cost of implémentation of facilities, operating cost;

— Greater simplicity of operation;

— Reduced maintenance and replacement of wom materials used in the p rocessing of raw iron ore and iron ore products compared to all-wet and all-dry routes;

— Réduction of auxiliary activities such as replacement of grinding media in bail mills (wet and dry);

— Iron ore ultrafine loss réduction;

— Forgoing an exhaust System or circuit for the removal of airbome ¹ ultrafines (dust) generated by ore processing and handling, as the natural moisture of the ore prevents the suspension of these particles.

jBRIEF DESCRIPTION OF THE INVENTION i

[0031] In order to achieve the above objectives, this invention provides process routes for comminution of iron ore or iron ore products at natural moisture, i.e. without the need to add water or a drying step to the process.

[0032] The invention consists of processing routes that combine grinding and classification equipment for a more efficient comminution process, such equipment being:

Roller Press (HPGR), Vertical Roller Mill (VRM), Roller Crusher (RC) and a high accélération screen of at least 10G.

[0033] Thus, the présent invention is aimed at an iron ore comminution process carried out at natural moisture, either from a material coming directly from the mine (ROM) or from already processed iron ore products (pellet feed, sinter feed, among others), where the processing uses at least one of the following equipment: vertical roller mill (VRM), roller press (HPGR), roller crusher (RC) and high accélération screen of at least 10G. For iron ore application, the vertical roller mill (VRM) will operate with overflow discharge and the ore drying option during grinding will not be used.

DESCRIPTION OF THE FIGURES

[0034] The detailed description given below refers to the attached figures, which:

— Figure 1 illustrâtes a wet iron ore beneficiation process (ROM), according to the State of the art;

— Figure 2 illustrâtes a wet process of beneficiation of iron ore products (pellet feed, sinter feed, among others), according to the state of the art;

— Figure 3 illustrâtes a dry raw iron ore beneficiation process (ROM) according to the state of the art;

— Figure 4 illustrâtes a dry process of beneficiation of iron ore products (pellet feed, sinter feed, among others), according to the State of the art;

— Figure 5 illustrâtes the process of beneficiation of raw iron ore or iron ore products at natural moisture, according to this invention;

— | Figure 6 shows the nine processing routes of thjis invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The following detailed description is in no way intended to limit the scope, applicability or configuration of the invention. More precisely, the following description provides the understanding necessary for the implémentation of exemplary embodiments. Using the teachings herein, those skilled in the art will recognize convenient alternatives that may be used without extrapolating the scope of this invention.

[0036] As will be obvious to any person skilled in the art, the invention is directed to comminution in the iron ore beneficiation process, without addressing any other steps such as concentration, for example. However, the invention is not limited to such particular embodiments.

[0037] Figure 1 shows a state-of-the-art process of wet iron ore beneficiation (ROM) containing the crushing 101, screening 102, grinding 103 and concentration 104 steps. Crushing step 101 may be performed in various stages (e.g. primary crushing to quaternary crushing), being carried out in closed circuit with screening step 102, which may be performed, for example, on vibrating screens. Grinding step 103 requires the addition of a significant volume of water. The ore concentration step 104 can be performed by gravitational, magnetic, flotation methods, etc.

[0038] Figure 2 shows a state-of-the-art process for beneficiation of wet iron ore products (pellet feed, sinter feed, etc.), where the comminution circuit contains a first grinding step 201, a filtration step 202 due to high moisture of the material, and a second grinding step 203. After comminution, the material goes through pelletizing step 204 to obtain the desired final product, which in this case is iron ore pellets.

[0039] Figure 3 shows a state-of-the-art process of dry iron ore beneficiation (ROM) containing crushing 301, screening 302, drying 303, grinding 304 and concentration 305 steps. Crushing step 301 may be performed in various stages (e.g. primary crushing to quaternary crushing), being carried out in closed circuit with screening step 302, which may be performed, for example, on vibrating screens. Drying 303 may occur within the grinding equipment itself by means of hot air flow from bumers and blowers. Concentration 305 can be performed by gravitational, magnetic, electrostatic methods, etc.

[0040] Figure 4 shows a state-of-the-art process for dry iron ore product beneficiation (pellet feed, sinter feed, among others), where the comminution circuit contains a drying step 401, a first grinding step 402 and a second grinding step 403. After comminution, the material goes through pelletizing step 404 to obtain the desired final product, which in this case is iron ore pellets. |

[0041] iThe following description will address (9) nine possible comminution routes of this invention. Routes apply for two iron ore source possibilities: 1) a first source of material coming directly from the mine (ROM), and 2) a second source of iron ore products already processed at the beneficiation plant (pellet feed, sinter feed, etc.) before entering this invention’s process.

[0042] This invention, illustrated in a simplified manner by Figure 5, is a beneficiation process whose comminution circuit 501 is fully performed at naturel moisture, either from a material coming directly from the mine (ROM) with up to 12% moisture by weight, or already processed iron ore products (pellet feed, sinter feed, etc.), also with up to 12% moisture. After comminution 501, the final product may be the comminuted iron ore itself, or concentration 502, pelletizing 503 or sintering 504 stages may be carried out according to the desired final product.

[0043] The 9 (nine) processing routes of the présent invention are illustrated in detail in Figure 6 and consist of:

— Route 1: The comminution circuit 501, at naturel moisture, occurs first in a roller press (HPGR) in up to three steps and is later reprocessed in a vertical roll mill (VRM) in up to three steps in sériés;

— Route 2: The comminution circuit 501, at naturel moisture, occurs first in a vertical roller mill (VRM) in up to three steps, and then is reprocessed in a roller press (HPGR) in up to three steps in sériés;

— Route 3: Comminution circuit 501, at naturel moisture, occurs in a roller press (HPGR) and is coupled in a closed circuit with a high accélération screen (at least 10G) where the coarse product (retained material) will be directed back to the roller press (HPGR) and fine product (passing material) is the final comminution product;

— Route 4: Comminution circuit 501, at naturel moisture, occurs in a vertical roller mill (VRM) and is coupled in a closed circuit with a high accélération screen (at least 10G), where the coarse product (retained material) will be redirected to the vertical roller mill (VRM) and the fine product (passing material) is the final comminution produit; | — Route 5: Comminution circuit 501, at naturel moisture, starts at the roller press (HPGR), the material goes on to be processed in a vertical roll mill (VRM) and is then classified intp a high accélération screen (of at least 10G), where the coarse product (retained material) returns to the roller press (HPGR), closing the circuit, and the fine product (passing material) is the final comminution product;

— Route 6: Comminution circuit 501, at naturel moisture, starts at the vertical roller mill (VRM), the material goes on to be processed in a roller press (HPGR) and is then classified into a high accélération screen (of at least 10G), where the coarse product (retained material) retums to the vertical roller mill (VRM), closing the circuit, and the fine product (passing material) is the final comminution product;

— Route 7: In comminution circuit 501, at natural moisture, the material is classified by the high accélération screen (of at least 10G), and its fine product (passing material) is processed by the roller press (HPGR) or vertical mill (VRM) in up to three steps. The product of the latter consists of the fine product, which is the final product of comminution; and coarse material (retained material) is also considered a product as it is traded in this way (sinter feed);

— Route 8: Comminution circuit 501, at natural moisture, occurs in a roll crusher (RC) and can be performed in several steps in a comminution sériés using equipment with double rollers or more; and — Route 9: The comminution circuit 501, at natural moisture, starts at the roller crusher (RC), and can occur in several steps in a comminution sériés using equipment with double rolls or more, and is then classified in a high accélération screen (of at least 10G), where the coarse product (retained material) retums to the roller crusher (RC), closing the circuit, and the fine product (passing material) consists of the final product.

[ 0044] Tests hâve shown that the présent invention produces different particle size products of less than 16 mm, particle size of less than 8 mm, particle size with up to 99.8% passing material in the 1 mm mesh and between 60% to 85% passing material in the 0.074 mm mesh.

Example 1

[0045] Pilot scale high-açceleration screen testing was performed using iron ore| with about 50% passing material at 1 mm, 11% moisture and very high loss on ignition (LOI) (about 10%), which is characteristic of a cohesive material that is diffîcult to screen at natural moisture. The undersize recovery of the 1.0 mm mesh ranged from 35% to 41%,! consistent with the amount of fines the sample had, which shows the efficiency of natural moisture screening even for such a cohesive material. Tables la, lb and le show the Chemical analysis, the particle size distribution of the tested sample and the undersize and oversize partition obtained in the pilot tests, as well as the mass balance of the test.

Table la: Chemical analysis

Chemical analysis (%) ίο

Fe	SiO2	P	AI2O3	Mn	TiO2	CaO	MgO	LOI
57.0	6.23	0.196	1.610	0.263	0.104	0.023	0.112	9.99

Table 2b: Particle size distribution of tests with high accélération screen

Test 1 Test 2

Mesh (mm)	Particle Size Distribution (%)	Particle Size Distribution (%)
Feed	Undersize	Oversize	Feed	Undersize	Oversize
40,000	100.00	100.00	100.00	100.00	100.00	100.00
31,500	98.04	100.00	96.69	98.38	100.00	97.50
25,000	96.38	100.00	93.89	97.79	100.00	96.59
19,000	92.17	100.00	86.79	95.07	100.00	92.40
16,000	90.09	100.00	83.27	92.63	100.00	88.64
12,500	86.11	100.00	76.57	88.87	100.00	82.84
10,000	82.59	100.00	70.62	85.43	100.00	77.54
8,000	79.09	100.00	64.72	82.21	100.00	72.57
6,300	75.60	100.00	58.83	78.23	100.00	66.44
2,400	57.07	99.27	28.05	57.64	99.50	34.97
1,000	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 3c: Mass balance of tests with high accélération screen.

	Flow	% Mass	| Flow	% Mass
Test 1	Feed	100.00	Test 2	Feed	100.00
Undersize	40.70	Undersize	35.10
	Oversize	59.30		Oversize	64.90

Example 2 I

[0046] Tests were performed on the HPGR and the test results are presented in table 2. After two processing runs in the same equipment, it was possible to obtain 56% of material retained in a 0.074 mm mesh. This highlights the high réduction ratio of fine 10 particles.

Table 4: Particle size distribution of the HPGR tests.

	Press feed	Ist run	2nd run
	%	%		%	0/		%	%
Size	Individua	%	Individu	/0	%	Individua Accumulât	%
Accumulate		Retaine			ed	Passing
(mm)	1	d Retained	Passing	al	d	Passing	1
	Retained		Retained			Retained	Retained
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	4.33	77.93	22.07	6.18	69.81	30.19	7.30	63.81	36.19
bypass	22.07	100.00	0.00	30.19	100.00	0.00	36.19	100.00	0.00

Example 3

[0047] 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 and 300 psi respectively, and under both conditions it was possible to reduce the material above 1 mm, which shows the good réduction ratio of particles in thicker fractions.

Table 5: Particle size distribution of tests with vertical roller mill.

Size (mm)	High Pressure - 1 run	Low Pressure - 2 runs
Feed	Product	Feed	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	1 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

[0048] Pilot tests were performed using a roller crusher (RC) with iron ore with about 43% retained in 1 mm and the results are presented in table 4, showing that it is 5 possible to reduce the material above 1 mm and provide a high génération of fine particles (less than 0.075mm). Tests hâve shown that the roller crusher is efficient in reducing size for various initial particle sizes.

Table 4: Particle size distribution of roller crusher tests.

Size (mm)	Feed	1 Run	2 Runs	4 Runs	5 Runs	6 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

[0049] Numerous variations on the scope of protection of this application are permitted. Thus, it is emphasized that the présent invention is not limited to the particular configurations/embodiments described above.

Claims (18)

1. L Process of comminution of iron ore or iron ore products at natural moisture, characterized in that it uses at least one equipment selected from the group consisting of roller press (HPGR), vertical roller mill (VRM), roller crusher (RC), and high accélération screen of at least 10G.
2. 2. Process according to Claim 1, characterized in that it first uses a roller press (HPGR) and then a vertical roller mill (VRM) in sériés.
3. 3. Process according to Claim 1, characterized in that it first uses a vertical roller mill (VRM) and then a roller press (HPGR) in sériés.
4. 4. Process according to Claim 1, characterized in that it uses a roller press (HPGR) with screening performed in a high-acceleration screen of at least 10G, in a closed circuit.
5. 5. Process according to Claim 1, characterized in that it uses a vertical roller mill (VRM) with screening performed in a high accélération screen of at least 10G, in a closed circuit.
6. 6. Process according to Claim 1, characterized in that it first uses a roller press (HPGR), then a vertical roller mill (VRM) and then screening in a high-acceleration screen of at least 10G, in closed circuit.
7. 7. Process according to Claim 1, characterized in that it first uses a vertical roller |mill (VRM), then a roller press (HPGR) and then screening in a highacceleration screen of at least 10G, in closed circuit.
8. 8. Process according to Claim 1, characterized in that it first uses screening in a high-acceleration screen of at least 10G and then a roller press (HPGR).
9. 9. Process according to Claim 1, characterized in that it first uses screening in a high-acceleration screen of at least 10G and then a vertical roller mill (VRM).
10. 10. Process according to Claim 1, characterized in that a roller crusher (RC) is used in several stages in sériés.
11. 11. Process according to Claim 1, characterized in that it first uses a roller crusher (RC) in several stages in sériés and then a high-acceleration screen of at least 10G in a closed circuit.
12. 12. Process according to Claim 10 or 11, characterized in that the roller crusher (RC) has 2, 4, 6, 8 or 10 rolls.
13. 13. Process according to any one of Claims 1 to 12, characterized in that the material fed in the process consists of iron ore from the mine (ROM - Run of mine) or iron ore products (pellet feed, sinter feed).
14. 14. Process according to any one of Claims 1 to 13, characterized in that the material fed into the process has up to 12% moisture by weight.
15. 15. Process according to any one of Claims 1 to 14, characterized in that the final comminution product has a particle size of less than 16 mm.
16. 16. Process according to any one of Claims 1 to 14, characterized in that the final comminution product has a particle size of less than 8 mm.
17. 17. Process according to any one of claims 1 to 14, characterized in that the final comminution product has a particle size of less than 0.074 mm.
18. 18. Process according to any one of claims 1 to 9, characterized in that the grinding on the roller press (HPGR) or the vertical roller mill (VRM) is carried out in up to three steps. | |