OA20236A - Process for the production of iron ore fines agglomerate and the agglomerated product. - Google Patents

Abstract

The present invention relates to a process for the production of iron ore fines agglomerate, resistant to handling, transport, and contact with water. The process consists of mixing iron ore fines with sodium silicate, nanomaterials, catalyst, fluxes and plasticizer; adjusting the moisture of the mixture; agglomerating the mixture by pelletizing, briquetting or extrusion; performing curing at room temperature. The process does not require energy input for heat treatment and allows obtaining an agglomerated product with high physical and metallurgical performance to replace metallic load, including sinter, in reduction furnaces, without the emission of harmful gases such as CO2, dioxins, furans, and SOx.

Description

PROCESS FOR THE PRODUCTION OF IRON ORE FINES AGGLOMERATE AND THE AGGLOMERATED PRODUCT

FIELD OF INVENTION

[001] The présent invention belongs to the field of mineralmetallurgical technologies and refers to a process for the production of iron ore fines agglomerate, résistant to handling, transport and contact with water. The process does not require energy input for heat treatment and allows obtaining a high-performance agglomerated product for replacement of metallic load, including sinter, in réduction furnaces, without the émission of harmful gases such as CO2, dioxins, furans, and SO_X.

BACKGROUND OF THE INVENTION

[002] The development of agglomération technologies stemmed from the need to recover fine particles, providing commercial use of these particles, as well as minimizing environmental impact caused by the production of fine or particulate material.

[003] Most usual applications of agglomération processes are concerned for the use of:

• fine-grained ores or concentrâtes, without causing damage to the load permeability and to the gas-solid reaction conditions in metallurgical furnaces;

• wastes, or fine by-products of other mining-metallurgical processes, for reuse or recycling thereof, in an appropriate manner; and • metallic waste (copper, iron, titanium) and other materials (paper, cotton, wood) for transportation or recycling.

[004] The iron ore agglomération operations are designed to give the loads to be fed into the réduction furnaces an adéquate shape and proper

mechanical résistance to the descending path of that load in the blast furnace, with percolation of gases through the load. The most common agglomération processes for iron ores used as load in steelmaking réduction furnaces are sintering, pelletizing, and briquetting.

[005] Iron ore sintering converts ore fines, usually with particle size distributions between 0.15 mm and 6.3 mm, called sinter feed, into larger agglomérâtes, called sinter. Its granulométrie range is between 5 mm and 25 mm of particle size, presenting physical, metallurgical, and permeability characteristics satisfactory for efficient blast furnace operation. Sintering is a process based on the incipient fusion of the components of a mixture consisting of a main component and additions of fluxes, promoting the rigid bonding of the particles, with the solidification of the liquid phase. Iron ore sintering is carried out in three stages: préparation of raw materials, ignition, and burning at levels of 1300°C, in addition to cooling.

[006] The sintering process is usually a large-scale process that requires considérable investment in CAPEx.

[007] Since sinter has a relatively high handling dégradation rate, it is not suitable for transportation over long distances, especially on ships. This is one of the reasons why sintering is installed near customers¹ blast furnaces.

[008] Pelletizing is the most recent agglomération process and it was a resuit of the need to use fine concentrâtes of magnetite from certain iron ores. Iron ore pellets are produced by agglomération of particles of less than 45 pm in size, forming pellets of from 8 to 16 mm, in dise or rotating drum. The material to be agglomerated must hâve a high spécifie surface (2,000 cm²/g), in addition to constant moisture. These pellets are usually hardened by means of heat treatment and used as feed in blast furnaces or in direct réduction. This hardening process has a high cost of capital, in addition to being intensive in

expenditure of energy.

[009] Briquetting consists on the agglomération of fine particles by means of compression, aided by binders, allowing the obtainment of a compacted product with adéquate shape, size, and mechanical parameters. The mixture between fine particles and agglomerate is pressed in order to obtain agglomérâtes called briquettes, which must hâve adéquate résistance for stacking, further treatment (curing, drying, or burning), transport, handling, and use in metallurgical reactors. Reducing the volume of the material, in addition to the technological benefits, allows fine materials to be more economically transported and stored.

[0010] The concern with environmental matters, resulting in stricter laws, in addition to the need to economically profit the wastes and fine particles generated in the processing of ores, made briquetting an important alternative to agglomerate fine materials giving them économie value.

[0011] Briquetting is carried out with binders when the material to be agglomerated does not hâve compressive and impact résistance, after being compacted. The applied pressures are usually low to avoid further fragmentation of the particles. When briquettes are made without binders, however, the success of the process dépends on the grinding or on plastic deformation of the particles to bring them as close as possible. The forces, in these cases, responsible for the cohésion of the particles after compaction should only ensure that the distance between the crystals becomes as small as possible. It is common to use lubricants, such as water, graphite, and other materials to reduce friction in the operation.

[0012] When the binding substance is in liquid form, the addition of water to the briquetting process is not required. The mixture of fine particles and the binder is then cold or hot pressed, thereby obtaining the briquettes.

The use of binders in the briquetting process implies the need for a briquette curing process. The curing of briquettes consists of reactions that occur between the particles and the binder, which will confer to the agglomerate the desired mechanical résistance. This step can be carried out at room température, in greenhouses and dryers (400°C), or in furnaces (above l,000°C).

[0013] Cold-cured agglomérâtes, that is, those that cure at room température, hâve a lower cost when compared to conventional curing processes where the agglomérâtes require thermal input to hâve a résistance gain.

[0014] The prior art features several cold ore agglomération technologies. These technologies are mainly based on the agglomération of fine ore particles using binding agents such as cernent, mortar, organic binders, and carbonaceous residues.

[0015] The physical résistance of agglomerated ore products is one of the main quality requirements for application in metallurgical reactors and has a direct impact on productivity and process costs. The nanomaterials technology provides possibilities for the agglomération of ore fines. Nanomaterials work as a composite network that confers to the agglomerated products, among other characteristics, high mechanical strength

[0016] The North American patent US 8,999,032, on behalf of Vale S.A., for example, describes the application of carbon nanotubes in iron ore, nickel, and manganèse agglomérâtes in order to increase their mechanical strength. The invention also relates to a process for preparing ore agglomérâtes that comprises the dispersion of carbon nanotubes in a matrix to form a mixture, its pelletizing, briquetting, or extrusion, and the drying of the agglomerate at 150 to 200°C.

[0017] The invention presented by the présent patent application differs from what is disclosed in the previous document since it does not require the drying step and due to the raw materials used in the agglomerate production. The previous document does not use catalysts and fluxes.

[0018] The prior art also includes other publications related to the process for the production of ore fines agglomérâtes, as exemplified below. [0019] The first patent related to briquetting was granted to William Easby, in 1848, for coal fines in the United States. The developed process allowed the formation of solid agglomérâtes of varying sizes and shapes, from 10 fine fractions of any type of coal due to the pressure exerted on this material.

The process steps initially involved drying the coal, followed by crushing and sieving. Subsequently, the fines are mixed with 6% cast asphalt, and the mixture is briquetted on roller machines producing solid agglomérâtes.

[0020] The US patent 9,175,364, also on behalf of Vale S.A., discloses 15 a method of producing agglomérâtes from the mixture of ore fines, with a granulometry of less than 0.150 mm, with sodium silicate, cassava starch, and micro silica. Water is added into the agglomération process, which can take place in a dise, pelletizing drum, or in a fluidized bed furnace. The agglomérâtes are subjected to the drying process at a température of from 100 to 150°C.

[0021] The présent invention differs from what is disclosed in the previous document, since it does not require the drying step and due to the raw materials used in the production of the agglomerate. The previous document has a restriction for using only ore fines with a granulometry of less than 0.150 mm and for not using catalysts and fluxes.

[0022] Patent application BR 10 2019 009592 0, on behalf of Vale S.A.

and Universidade Fédéral de Ouro Preto, refers to the reuse of iron mining tailings for the production of briquettes by compaction using mixtures of these tailings with iron ore fines and liquid sodium silicate, as a binder. The briquettes are subjected to curing at a température of from 250 to 550°C for a period of 20 to 40 minutes.

[0023] The présent invention differs from what is disclosed in the previous document, since it does not require the drying step and due to the raw materials used in the production of the agglomerate.

[0024] The US patent 6,921,427, filed in 2002 on behalf of the Council of Scientific & Industrial Research, refers to a process of cold briquetting and pelletizing of ferrous or non-ferrous ores fines, using an iron-containing minerai binder, for metallurgical applications.

[0025] The process consists of the steps of mixing about 80 to 95% of the fine material with 3 to 10% of an iron-containing minerai binder and, optionally, with 2 to 6% of water and from 0.05 to 0.20% of a surface activate agent (triethanolamine) can be added to form a homogenized dry mixture. Subsequently, the mixture is agglomerated to form a compacted mass that is then subjected to a curing stage for 3 to 20 days by exposure to atmospheric air for 10 to 14 hours. During curing, the produced agglomérâtes exposed to atmospheric air are sprayed with water every 12 hours to develop cold strength.

[0026] In this patent, it is described that the binder agent has an important rôle in the development of cold strength by hydration in the agglomerated product. The Chemical composition ofthe binder is 25-45% by weight of FeO, 40-60% of Cao+MgO and 12-18% of S1O2+AI-O.

[0027] The tests were carried out producing agglomérâtes in the form of briquettes, blocks, and pellets, by using different combinations of iron oxides, metals, and other minerai fines such as powders and slurries of blast furnaces, of oxygen-inflated furnaces (BOF), rolling scale, fines and slurries

contaminated with oil and coal, lime, limestone, dolomite, dunite, quartzite, coke and carbonaceous materials using iron bearing hydraulic minerai binder. [0028] The process presented in US 6,921,427 differs from the présent invention regarding the binders and other inputs used. While the presented 5 document reports the use of a minerai binder containing iron and triethanolamine, which is an organic compound, the présent patent application proposes the use of sodium silicate as a binder agent. Moreover, US 6,921,427 makes use of carbonaceous materials and has a significantly different curing step.

[0029] Mohanty, M.K. et al (2016), in their publication entitled A novel technique for making cold briquettes for charging in blast furnace describes the production of extruded agglomérâtes in which the concept of cold agglomération is presented. Iron ore fines and carbonaceous materials (such as coke fines and blast furnace powders) are mixed with Portland cernent, which is used as a binder, and also with a clay minerai, acting as a rheological modifier. The mixture is subjected to a rigid extrusion process at high pressure (100 kg/cm²) and under vacuum (O.5xlO³Bar) and does not require heat treatment of the resulting extruded agglomérâtes. The characteristics of the produced agglomérâtes and the assessments of their metallurgical behavior (reducibility) are presented, comparing them with iron ore.

[0030] The présent invention differs from what is disclosed in the previous document due to the raw materials used in the production of the agglomerate. The présent invention does not use carbonaceous materials and 25 does not apply Portland cernent as a binder.

[0031] The présent invention is related to a process for the production of iron ore fines agglomérâtes of high physical and metallurgical performance for replacement of metallic load, including sinter, in réduction furnaces. The agglomérâtes are produced from the mixture of iron ore fines (sinter feed, pellet feed, and ultrafine tailing), with a particle size distribution of less than 10 mm, with a binder (sodium silicate) and additives such as nanomaterials, catalysts, fluxes, and plasticizers. The agglomération process can occur by pelletizing in dise or in a drum, by briquetting, or by extrusion. Agglomérâtes are subjected to curing at room température for 2 days in a covered place until they reach sufficient water résistance to be exposed to weather and transport. Complété curing occurs in up to 10 days.

[0032] The présent invention has advantages in comparison to the processes for agglomération of iron ores known from the prior art, such as: (i) curing at room température - it does not require energy input for heat treatment and there are no émissions of harmful gasses such as CO2, dioxins, furans, and SO_X, (ii) possibility of use of iron mining tailings, (iii) no use of coal or other carbonaceous material, (iv) obtaining agglomerate with high physical performance, résistant to handling and transport over long distances, in addition to being water-resistant in less time, optimizing the logistics of production flow.

OBJECTIVES OF THE INVENTION

[0033] The présent invention has as main objective providing a new process for the production of iron ore fines agglomerate intended for the replacement of metallic load in réduction furnaces (granules, pellets, sinter) with excellent physical and metallurgical performance.

[0034] Another objective of the présent invention consists in obtaining an agglomerated product with high physical résistance to handling and transportation over long distances, in addition to being water-resistant in less time, which optimizes the production flow logistics.

[0035] Another objective of the présent invention is to reduce the generated environmental impact since fossil fuels are not used in the agglomerate constitution. In addition, the curing performed at room température does without energy input and renders the production process free of atmospheric émissions (particulates, SO_X, dioxins, furans, CO2) and other volatile compounds.

SUMMARY OF THE INVENTION

[0036] The présent invention, in its preferred embodiment, discloses a process for the production of iron ore fines agglomerate for replacement of metallic load in réduction furnaces comprising the following steps:

a) mixing a nanomaterial and a catalyst to sodium silicate for preparing the binder mixture;

b) mixing 1-5% of the binder mixture from step a) with 70-100% iron ore fines, 0-30% fines of fluxes and 0-5% plasticizer in intensive mixer;

c) adjusting the moisture in such a way to obtain the amount of 0-30% of water weight in the mixture;

d) performing agglomération by pelletizing, briquetting or extrusion;

e) keeping the agglomérâtes at room température for 2-10 days for curing;

wherein the following dosages are used:

0.05 to 2% by weight of nanomaterial relative to sodium silicate;

0.05 to 5% by weight of catalyst relative to sodium silicate.

BRIEF DESCRIPTION OF DRAWINGS

[0037] The présent invention is described in detail based on the respective figures:

ίο

[0038] Figure 1 illustrâtes a simplifiée! block diagram of the process for the production of agglomérâtes from iron ore fines.

[0039] Figure 2 illustrâtes a graph showing the réduction of curing time at room température as a function of the use of catalyst.

[0040] Figure 3 shows the granulométrie distribution of the sinter feed sample used in the pilot test.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Although the présent invention may be susceptible to different embodiments, the preferred embodiments are shown in the Figures and in the following detailed discussion, with an understanding that the présent description must be considered as an exemplification of the principles of the invention, and they are not intended to limit the présent invention to what was hereby illustrated and described.

[0042] The subject matter of the présent invention will be detailed hereafter by the way of example and not limitative, since the materials and methods hereby disclosed may comprise different details and procedures without escaping from the scope of the invention. Unless otherwise stated, ail parts and percentages shown below are weight percentages.

[0043] The main approach of this invention is related to a process for the production of iron ore fines agglomerate comprising the following steps: a) mixing a nanomaterial and a catalyst to sodium silicate for preparing the binder mixture;

b) mixing 1-5% of the binder mixture from step a) with 70-100% iron ore fines, 0-30% fines of fluxes and 0-5% plasticizer in intensive mixer;

c) adjusting the moisture in such a way to obtain the amount of 0-

30% of water weight in the mixture;

d) performing the agglomération by pelletizing, briquetting or extrusion;

e) keeping the agglomérâtes at room température for 2-10 days for curing;

wherein the following dosages are used:

0.05 to 2% by weight of nanomaterial relative to sodium silicate;

0.05 to 5% by weight of catalyst relative to sodium silicate.

[0044] The process for the production of agglomerate, represented by the block diagram of Figure 1, preferably begins with the mixing and dispersion of the additives in sodium silicate, which is the binder agent applied in the process.

[0045] The sodium silicate used in the process has preferably the SiO₂/Na₂O molar ratio of from 1.8 to 4.5, 36 to 48% of solids, and the following composition: 5 - 14.6% of Na₂O; 22 - 33.2% of SiO₂; 54.0-73.0% of H₂O.

[0046] As an additive to sodium silicate, there is the addition of nanomaterial under mechanical stirring, at a dosage of 0.05 to 2% by weight relative to the amount of sodium silicate used in the mixture. The nanomaterial is selected from the group consisting of: carbon nanotube, exfoliated graphite, functionalized microsilicate, tubular nano silica, tubular halloysite, carbon nanofiber, and graphene.

[0047] As a catalyst to accelerate the curing process at room température, sodium pyrophosphate, magnésium hydroxide, propylene carbonate, glycerin carbonate, calcium hydroxide, calcium oxide, glycerol triacetate, aluminum chloride, aluminum hydroxide, triacetin, diacetin, and metallic aluminum can be used. Under mechanical stirring, 0.05 to 5% by weight of catalyst relative to the amount of sodium silicate used in the mixture are added.

[0048] The second step of the process for the production of agglomerate

consists on adding 1 to 5% of the agglomerating mixture (formed by sodium silicate, nanomaterial, and catalyst), to from 70 to 100% by weight of iron ore fines, 0 to 30% by weight of fluxes and 0 to 5% by weight of plasticizer. Mixing should preferably be carried out in an intensive mixer for 10-180 seconds.

[0049] The iron ore fines to be used in the process must hâve a particle size distribution of less than 10mm, d₉₀ between 1 and 8mm, and maximum moisture of 25%. Sinter feed, pellet feed, and ultrafine iron ore tailing can be used, which, in the prior art, is disposed of in tailings dams. The preferred Chemical composition of ore fines consists of 30 to 68% FeTotai, 0.5 to 15% S1O2, 0.1 to 5.0% AI2O3, 0.001 to 0.1% P, 0.1 to 2% Mn and 0.1 to 8% PPC (loss on ignition).

[0050] The fluxes used in the process for the production of agglomérâtes are selected from the group consisting of calcium hydroxide, calcitic limestone, dolomitic limestone, calcined magnesite, serpentinite, talc, dunite, and olivine. [0051] The plasticizing agent used in the process for the production of agglomerate is selected from the group consisting of bentonite, corn starch, cassava starch, glycerin, and CMC (carboxymethyl cellulose).

[0052] The third step of the process for the production of agglomerate is to adjust the moisture by adding water in such a way that the mixture has optimal moisture (0 to 30%) for the subséquent agglomération process.

[0053] The fourth step of the process for the production of agglomerate consists of carrying out agglomération by pelletizing, briquetting, or extrusion. [0054] If the agglomération method by briquetting is chosen, the mixture should preferably contain moisture in the range of 2-10%. The briquetting can be carried out by means of press with rollers containing cavities appropriate for obtaining briquettes with the dimensions of 20-40 mm x 10-30 mm x 5-20 mm, and with the necessary pressure adjustment to obtain briquettes with

bulk density between 2.5 to 3.5 g/cm³. Bulk density control is necessary to obtain briquettes with adéquate porosity.

[0055] If the agglomération method by pelletizing is chosen, the mixture should preferably contain moisture in the range of 8-11%. The pelletizing 5 process can be carried out in a rotary dise or drum, forming spherical pellets with 10-30 mm in diameter.

[0056] If the agglomération method by extrusion is chosen, the mixture should preferably contain moisture in the range of 10-30%. The extrusion process can be carried out on extruders which, preferably, allow the formation 10 of cylindrical agglomérâtes of 530 mm in diameter and 5-30 mm in height.

[0057] The fifth step of the process for the production of agglomerate consists in curing at room température.

[0058] The use of catalysts to promote the hardening of sodium silicate is efficient in reducing the curing time from 15 days to 2 days, thereby allowing 15 the transport and handling of the product in rainy conditions (bad weather).

The catalyst promûtes the formation of insoluble compounds and polymerization of sodium silicate, making the product more résistant to water in a shorter cure time, as shown in Figure 2.

[0059] Complété curing at room température, which occurs from 2 to 10 20 days, allows the final moisture of the agglomérâtes to be less than 3%.

[0060] Optionally, if it is necessary that the agglomérâtes get résistance in the shortest possible time, it can be chosen to perform the drying in horizontal furnace for 10 to 30 minutes at a température of from 100 to 550°C. However, this option is not recommended because it is not considered an 25 environmentally sustainable alternative.

[0061] The iron ore agglomerate obtained by means of the présent invention is presented as an alternative to replace metallic load in réduction furnaces since it présents adéquate Chemical, physical and metallurgical quality, such as presented in Table 1, Table 2 and Table 3 as follows.

Table 1 - Chemical quality of the agglomérâtes obtained by means of the process ofthe présent invention j Briquettes

I FeT (30-68%); SiO₂ (0.5-15%); AI₂O₃ (0.1-5%); P (0.001 to 0.1%);

I Mn (0.1-2%); CaO (0-15%), MgO (0-5%); PPC (0.1 to 8%).

t

I

J Pellets

I FeT (30-68%); SiO₂ (0.5-15%); Al₂O₃ (0.1-5%); P (0.001 to 0.1%);

I Mn (0.1-2%); CaO (0-15%), MgO (0-5%); PPC (0.1 to 8%).

j|

I Extruded|

I FeT (30-68%); SiO₂ (0.5-15%); AI₂O₃ (0.1-5%); P (0.001 to 0.1%);|

I Mn (0.1-2%); CaO (0-15%), MgO (0-5%); PPC (0.1 to 8%).।

Table 2 - Metallurgical quality of the agglomérâtes obtained by means of the process ofthe présent invention j

Briquettes|

ISO 7215 reducibility: >60%|

ISO 4696-2 RDI: %-2.8 mm: <25%|

ISO 4698 swelling: < 25%|

Pellets|

ISO 7215 reducibility: >60%

ISO 4696-2 RDI: %-2.8 mm: < 25%

ISO 4698 swelling: < 25%

Extruded

ISO 7215 reducibility: >60%

ISO 4696-2 RDI: %-2.8 mm: < 25%

ISO 4698 swelling: < 25% I j

Table 3 - Physical quality of the agglomérâtes obtained by means of the process of the présent invention * !

I Briquettes j

[ JIS M8711 ShatterTest: % + 10mm: > 90% |

J ISO 3271 Tumbler Test: % +6.3mm: >85%

I ISO 3271 Abrasion: %-0.5mm: < 10%

I ISO 8371 Crackling: %-6.3mm: < 5% | Shatter Test JIS M8711 *Weathering: %+10mm: > 80% | Dry compressive strength: daN/briquette > 200 | Pellets j JIS M8711 Shatter Test: %+10mm: > 90% | ISO 3271 Tumbler Test: % +6.3mm: >85%

I ISO 3271 Abrasion: %-0.5mm: < 15% | | ISO 8371 Crackling: %-6.3mm: < 5%

JIS M8711 Shatter Test *Weathering: %+10mm: > 80%

Dry compressive strength: daN/briquette > 150 | Extruded

I JIS M8711 Shatter Test: %+10mm: > 90% ί ISO 3271 Tumbler Test: % +6.3mm: >85%

I ISO 3271 Abrasion: %-0.5mm: < 15%| | ISO 8371 Crackling: %-6.3mm: <5%I

I ShatterTest JIS M8711 *Weathering: %+10mm: > 80%I j *weathering: immersion into water for 1 hour.|

Example

[0062] In order to evaluate the quality, characteristics, and 5 performance of the agglomérâtes produced by means of the process described by the présent invention, pilot scale tests were performed for the production of briquettes, using the sinter feed as iron ore fines.

[0063] The sinter feed used had moisture of less than 8% and dgo between 2 to 8mm. The particle size distribution curve is shown in Figure 3, wherein the sample used was found to be in the granulométrie range evidenced by the hatched area. The tests were carried out in batches of 100 kg of sinterfeed each.

[0064] The sodium silicate solution used presented a SiO2/Na2O molar ratio of 2.15, solids percentage of 47%, being composed by 14.6% NazO, 31,4% SiCh, and 54% H2O. The solution presented true density of 1.57 g/cm³ and viscosity of 1175 cP at 25°C. Functionalized microsilicate was added at a dosage of 0.1% relative to the amount of sodium silicate used in the mixture. The calcium hydroxide catalyst was added at a dosage of 2.5%. Mechanical mixing was performed for 5 minutes to obtain the final binder mixture.

[0065] 3% of said binder mixture was added to 71.7% of sinter feed, 25% of fines of fluxes (calcitic limestone and serpentinite) and 0.3% of bentonite. Mixing was carried out in the Eirich intensive mixer for 120 seconds.

[0066] Briquettes were produced using a Komarek briquetting press, at 200 Bar, which allowed the formation of pillow type morphology briquettes, with dimensions of 25 x 20 x 15 mm and moisture <0.5%. Curing was carried out at room température for 5 days.

[0067] The quality of the briquettes was evaluated concerning physical, Chemical, and metallurgical properties, according to procedures specified in standards for the évaluation of iron ores.

[0068] The compression strength was evaluated using dry briquettes in an automatic press with a ± 5 daN sensitivity, to evaluate the compressive load that causes its breakdown. The same test was performed with briquettes after immersion in water for a period of 1 hour. The average resuit obtained for dry briquettes was > 120 daN/briquettes in the largest area (25 x 20 mm), and for briquettes, after immersion, there was a 30% résistance drop.

[0069] The test for abrasion résistance and tumble indices was performed using 1.5 kg of dry briquettes subjected to 464 révolutions in a drum. At the end of the test, the mass was sifted in sieves with openings of 6.3

mm and 0.5 mm. The tumble indices (ISO 3271), which consists of the percentage of mass retained at 6.3 mm, was > 85%. The abrasion indices (ISO 3271), which consists of the percentage of passing mass in 0.5 mm, was < 15%. [0070] The shatter strength test was performed with a 3 kg sample of dry briquettes subjected to four successive drops of three meters. At the end of the last drop, the mass was sifted using a sieve with a 10mm opening. The Shatter Strength Index (Shatter - JIS M8711), which consists of the mass percentage greater than 10mm, was > 95%.

[0071] For determining the decrepitation index (DI), the test mass was rapidly heated from room température up to 700°C, maintained at this température and then air cooled until reaching room température. Sieving was carried out with a sieve containing 6.3 mm square openings. The Decrepitation Index, which consists of the mass percentage of the material with a size greater than 6.3 mm, was < 5%.

[0072] The reducibility index (RI) of the briquettes has been evaluated according to ISO 7215, under conditions similar to the conditions that prevail in the blast furnace réduction zone. The average resuit obtained was > 60%.

[0073] The low-temperature réduction-dégradation test (RDI) was performed in accordance with ISO 4696-2, after réduction with CO and N gases under conditions similar to the low-temperature reduction-zone of the blast furnace. The average resuit was < 15%.

[0074] Table 4 présents a comparison between the physical quality of the briquette produced by the process of the présent invention in relation to other products such as sinter (obtained by means of the traditional sintering process), pellet (obtained by means of the traditional pelletizing process), and the commercial granules from Brazil and Australia. It is possible to prove that the briquette produced by means of the process of the présent invention has high physical and metallurgical performance and, for this reason, it is considered as an alternative for substituting the metallic load of réduction furnaces with less

environmental impact.

[0075] Note that, in Table 4, the RDI acronym refers to the dégradation test under low-temperature réduction, S corresponds to the permeability index, APmax corresponds to the maximum gas pressure drop, TS200 corresponds to the dripping start température, Td corresponds to the softening end température, and ΔΤ refers to the température gradient corresponding to the softening and melting zone (Td - TS200).

Table 4 - Comparison of the briquette quality parameters obtained by means ofthe process ofthe présent invention

Vale BRIQUETTE	Tumble	Abrasion	Decrepitation	RDI	Reducibility	S	ΔΡ max	TS2OO	ΔΤ	Td	Fines of adhérents
%>6,3 mm	%<0,5 mm	%>4,75 mm	%-2,8 mm	%	kg*C/cm2	mmHîO	°c	°C	°C	%
85	lü	: ..0.1	15	60	30	3000	1150	200	®ΐ3δ|β	0.5
Vale Sinter	65	NA	NA	25	65	30	3000	1150	200	1350	NA
Vale Pellet	90	6	0	5	60	100	5000	1100	300	1400	NA
Vale Granulate 1	75	18	3	26	66	45	3247	1087	312	1427	2.8
Vale Granulated 2	79	15	2	15	58	41	3440	1104	250	1392	3
Vale Granulated 3	81	15	0.5	32	64	30	2363	1156	296	1457	2.02
Vale Granulated Average	78	16	2	24	63	38	3017	1116 '	286	1425	3
AUS Granulated 1	85	10	6	26	56	56	4897	1111	282	1406	3.89
AUS Granulated 2	85	8	3	19	70	44	4897	1128	269	1429	0.96
AUS Granulated 3	85	9	4	23	60	34	3676	1146	228	1418	2
AUS Granulated Averages*	85	9	4	23	62	45 . -, '	4490	1128	260	1418	2

[0076] Thus, although only some embodiments of the présent invention hâve been shown, it will be understood that various omissions, substitutions, and changes can be made by a skilled person, without departing from the spirit and scope of the présent invention. The described 5 embodiments should be considered in ail aspects only as illustrative and not restrictive.

[0077] It is expressly provided that ail combinations of the éléments that perform the same function substantially in the same manner to achieve the same results are within the scope ofthe invention. Substitutions of éléments 10 from one described embodiment to another are also fully intended and

Claims (13)

1. Process for the production of iron ore fines agglomerate for metallic load replacement in réduction furnaces, characterized in that it is conducted without using carbonaceous material and by comprising the following steps:

a) mixing a nanomaterial, a catalyst and sodium silicate for preparing the binder mixture;

b) mixing 1-5% of the binder mixture from step a) with 70-99% iron ore fines, 0-30% fines of fluxes and 0-5% plasticizer in intensive mixer;

c) adjusting the moisture in such a way as to obtain the amount of 0-30% of water weight in the mixture;

d) performing agglomération by pelletizing, briquetting or extrusion;

e) keeping the agglomérâtes at room température for 2-10 days for curing;

wherein the dosage of 0.05 to 2% by weight of nanomaterial relative to sodium silicate is used; and the dosage of 1.5 to 3.5% by weight of catalyst relative to sodium silicate is used;

the catalyst used in the process consists of calcium hydroxide or sodium pyrophosphate or propylene carbonate; and wherein the fluxes used in the process consists of calcitic limestone or dolomitic limestone or serpentinite or calcium hydroxide.

2. Process, according to claim 1, characterized in that the nanomaterial used in step a) is selected from the group consisting of carbon nanotube, exfoliated graphite, functionalized micro-silicate, tubular nano-silica, tubular halloysite, carbon nanofiber, and graphene.

5

3. Process, according to claim 1, characterized in that the sodium silicate used in step a) has a SiO2/Na2O molar ratio from 1.8 to 4.5 and solids percentage from 36 to 48%.

4. Process, according to claim 1, characterized in that the iron ore fines used in step b) hâve granulometry less than 10mm, iron content (FeTotal) 10 from 30 to 68%, and are selected from the group consisting of sinter feed, pellet feed, and ultrafine iron ore tailings.

5. Process, according to claim 1, characterized in that the plasticizer used in step b) is selected from the group consisting of bentonite, corn starch, cassava starch, glycerin, and CMC (carboxymethyl

15 cellulose).Process, according to claim 1, characterized in that the plasticizer used in step b) is selected from the group consisting of bentonite, corn starch, cassava starch, glycerin, and CMC (carboxymethyl cellulose).

6. Process, according to claim 1, characterized in that the mixing of 20 step b) is carried out in an intensive mixer for 10 to 180 seconds.

7. Process, according to claim 1, characterized in that the curing of step e) is carried out in a covered place in the first 2 days.

8. Process, according to claim 1, characterized in that, in step e), drying can be carried out in a horizontal furnace for 10 to 30 minutes at a 25 température of 100 to 550oC.

9. Iron ore fines agglomerate produced by the process as defined in claim 1 characterized by having Chemical, physical and metallurgical qualities suitable for replacing metallic load in réduction furnaces, to wit:

30 to 68% FeTotal, 0.5 to 15% SiO2, 0.1 to 5.0% AI2O3, 0.001 to 0.1% P,

0.1 to 2% Mn; 0 to 15% CaO and 0.1 to 8% PPC (loss on ignition); ISO 7215 reducibility >60%; Dégradation under Low Température Réduction (RDI) ISO 4696-2 <25%; ISO 4698 swelling <25%; Fall Résistance Index (Shatter - JIS M8711, which consists of the mass percentage greater than 10mm) >90%; Drumming Index (Tumbler Test ISO 3271, which consists of the percentage of mass retained in 6.3 mm) >85%; Abrasion Index (ISO 3271, which consists ofthe percentage of through mass in 0.5 mm) <15%; and Crackle Index (ISO 8371, which consists of the percentage of mass of the material largerthan 6.3 mm) <5%..

10. Iron ore fines agglomerate according to claim 9, characterized by having the characteristics of résistance to handling, transport, water, and weathering, to wit: Drop Résistance Index (Shatter - JIS M8711, which consists ofthe mass percentage greaterthan 10mm)> 80% after 1 hour of immersion in water; and Dry Compression Resistance> 150 daN / briquette.

11. Iron ore fines agglomerate, according to claim 9, characterized by having the a pillow type briquette shape whose dimensions are 20-40 mm x 10-30 mm x 5x20 mm.

12. Iron ore fines agglomerate, according to claim 9, characterized by having the shape of a spherical pellet whose diameter is 10-30mm.

13. Iron ore fines agglomerate, according to claim 9, characterized by having a cylindrical shape of 5-30 mm in diameter and 5-30 mm in height