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(11) | EP 4 502 197 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 153(4) EPC |
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| (54) | METHOD FOR PRODUCING HIGH IRON-CONTENT PRODUCTS FROM IRON ORE FINES AND BIOMASS, AND PRODUCTS THEREOF |
| (57) This invention refers to a process for obtaining a product of high iron content and
high physical and metallurgical performance for use in reduction furnaces (blast furnaces,
and direct reduction) and melting furnaces (smelters, melters, and electric furnaces),
aiming at the sustainable production of iron and steel. The process consists of mixing
iron ore fines with biomass, binders, nanomaterials, additives, and catalysts, and
performing subsequent steps of comminution, agglomeration, heat treatment, solid-solid
separation, and coating. |
FIELD OF INVENTION
[0001] This invention is included in the field of mineral/metallurgical technologies and pertains to a process for obtaining high-performance products from fines of iron ore and renewable carbon source from biomass. The process allows obtaining high iron content products, with high physical and metallurgical performance for use in reduction furnaces (blast furnaces and direct reduction) and melting furnaces (melters and electric arc furnaces), aiming at the sustainable production of iron and steel.
BACKGROUND OF INVENTION
[0002] The development of agglomeration technology resulted from the need to recover fine particles, which allowed the commercial utilization of such particles, as well as minimized the environmental impact caused by the production of fine or particulate material.
[0003] The most frequent applications of agglomeration processes are for the utilization of:
- fine-grained concentrates or ores, without causing damage to the permeability of load and to the gas-solid reaction conditions in metallurgical furnaces;
- wastes, or fine byproducts from other mineral/metallurgical processes, for their reuse or recycling, in an appropriate manner; and
- metallic waste (copper, iron, titanium) and other materials (paper, cotton, wood) for transport or recycling.
[0004] The agglomeration operations of iron ore, and its partially or totally reduced compounds, are intended to give the loads to be fed into the reduction reactors and/or melters a suitable shape and mechanical resistance appropriate to the countercurrent flow of the downward solid load and heating gases and/or upward reducers, as well as to the transport, storage, and ensiling processes, before loading into reduction reactors and melters for the production of pig iron or steel. The most common agglomeration processes of iron ores and their reduced products used as load in reduction furnaces and melters in the steel industry are: sintering and pelletizing (for iron oxides) and briquetting (for iron oxides and metal iron - DRI).
[0005] Pelletizing is the most recent agglomeration process that results from the need to use fine concentrates of magnetite from certain iron ores. Iron ore pellets are produced by agglomeration of particles with a size of less than 45 µm forming pellets of 8 to 16 mm, in disc or rotary drum. The material to be agglomerated needs to have a high specific surface (2,000 cm2/g), in addition to constant humidity. These pellets are typically hardened by heat treatment and used as blast furnace feed or in direct reduction. This hardening process has a high capital cost, in addition to being energy-intensive.
[0006] Briquetting consists of the agglomeration of fine particles by means of compression, aided by binders, allowing the achievement of a compacted product, with appropriate shape, size, and mechanical parameters. The mixture between fine particles and binder is pressed in order to obtain agglomerates referred to as briquettes, which should have appropriate resistance for stacking, further treatment (curing, drying, or burning), transport, handling, and use in metallurgical reactors. The reduction of material volume, in addition to technological benefits, allows fine materials to be transported and stored with better cost-effectiveness.
[0007] The concern with environmental issues, resulting in stricter laws, in addition to the need to utilize, in a cost-effective manner, the waste and fine particles generated in the processing of ores, have made briquetting an important alternative to agglomerate fine materials warranting them with economic value.
[0008] Briquetting is performed with binders when the material to be agglomerated does not have resistance to compression and impact, after being compacted. Pressures used are usually low to avoid further fragmentation of particles.
[0009] This invention refers to a process for obtaining high physical and metallurgical performance products, which may be agglomerated or not. Products resulting from this invention are produced from the mixture of iron ore fines (including tailings, pre-reduced, and metallized), biomass, binders, nanomaterials, additives, and catalysts. If the products are agglomerated, the agglomeration process can occur by pelletizing in pelletizing disc or drum, by briquetting, or by extrusion.
[0010] The carbothermal reduction process, used in this invention, consists of the chemical processing of oxide reduction with the use of CO (carbon monoxide) gas that comes from a substance carrying the carbon element, traditionally in the "forms" of mineral coal, coke, or charcoal.
[0011] The prior art has several carbothermal reduction technologies. These technologies are based on the carbothermal reduction of iron ore agglomerates (pellets, briquettes, and extrudates) using coal, charcoal, or coal coke, with a high participation of organic and inorganic binders (tar, cement, silicates, bitumen, starch, among others), aiming to provide a minimum physical resistance for handling, usually in weathering conditions, and thermochemical requests in the processes that are used. Many of these technologies aim to recycle waste with high iron and/or carbon contents (such as scales, screening fines, process exhaust powders, fines and thickener sludges collected in dedusting systems). Self-reducing agglomerates are used in conventional reduction furnaces as small/medium blast furnaces and reduction-fusion reactors (e.g.: Tecnored, ITmk3, Hi-sarna, and Fastmet). The heat supplied for the direct reduction and carbon gasification reactions (Solution Loss at temperatures > 850 °C) to occur is supplied in conventional furnaces by the burning of solid fuels (cokes, coals, and biomasses), and by the burning of gases (LPG, NG, and Gases generated in steel processes, such as Coke Oven Gas, Blast Furnace Gas, and Steelmaking Gas).
[0012] This invention minimizes some problems through the use of microwaves instead of conventional furnaces where solid fuels and gases emitting GHG are used; needs for high dosages of binders; long time for product reduction, low resistance to contact with water, high generation of fines by transport and handling, high generation of fines by thermal shock, and contamination of undesirable elements to the product from certain binders. This invention introduces a simplified process of unit operations that reduce CAPEX and OPEX costs.
[0013] In particular, this invention, on its Route 3, brings a significant advantage over prior art documents.
It refers to the lack of prior agglomeration of large volumes of base mixture, significantly reducing process costs (CAPEX and OPEX). There is no technology in the prior art capable of industrially performing carbothermal reduction without implying the prior agglomeration of the mixture of iron ore fines and biomass. This invention, therefore, proves to be significantly innovative, showing high reduction efficiency (metallic Fe > 50%, as shown in Figure 5).
[0014] This invention brings a number of advantages compared to the processes usually used industrially, such as:
- the possibility of using different sources of iron ore fines (sinter feed, pellet feed, and/or ultrafine tailings);
- the possibility of using different types of biomass, including pyrolyzed or not;
- wide applicability in reduction and melting furnaces, owing to the physical and metallurgical qualities of the product obtained;
- relevant technological alternative capable of offering commercial and strategic benefits for a company and its customers;
- greater process route adaptability, providing steel customers with a BF (blast furnace) route to extend the useful life of their assets, reducing CAPEX, without compromising the achievement of short- and medium-term CO2 emission reduction goals;
- reduction of greenhouse gas (GHG) emissions in the iron and steel production chain;
- cost reduction owing to the possibility of lower consumption of binders for their agglomeration and the possibility of greater use of iron-poor ores with higher silica content, which may be concentrated, at a later stage, by magnetic separation, since the materials resulting from the reduction of hematite are magnetic or strongly paramagnetic.
PURPOSES OF INVENTION
[0015] This invention aims to facilitate a new process of obtaining a high iron product that has greater process route adaptability, providing steel customers with the extension of the useful life of their assets, reducing CAPEX, without compromising the achievement of goals of reducing CO2 emissions.
[0016] Another purpose of this invention is to obtain a product from biomass and iron ore fines with excellent physical and metallurgical performance, and of wide applicability in reduction and melting furnaces.
[0017] Another purpose of this invention is to reduce the environmental impact generated since it allows reducing the emission of greenhouse gases (GHG) in the iron and steel production chain, as a result of the replacement of natural gas and mineral coal, by biomass for the reduction of iron oxides, in addition to allowing the utilization of iron ore tailings, which usually has their ultrafine fraction disposed of in tailings dams.
SUMMARY OF INVENTION
[0018] This invention, as shown by Figure 1, reveals a process for obtaining a high iron product from iron ore fines and renewable carbon source from biomass, comprising the following steps:
- a) mixing fines of iron ore, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
- b) performing at least one step out of the group consisting of agglomeration and carbothermal reduction;
- c) performing at least one step out of the group consisting of solid-solid separation, carbothermal reduction, and agglomeration.
[0019] Still, this invention, as shown by Figure 1, may comprise a further step of:
- a) performing at least one step out of the group consisting of drying/curing and coating application;
- b) performing carbothermal reduction;
- c) performing coating application.
BRIEF DESCRIPTION OF DRAWINGS
[0020] This invention is described in detail based on the respective figures:
Figure 1 illustrates a flowchart of the process of obtaining metallized and pre-reduced iron ore products by microwave carbothermal reduction, as well as iron ore briquettes with biomass, according to this invention.
Figure 2 illustrates a schematic representation of the microwave oven that was used during the bench-scale carbothermal reduction testing step (Routes 2 and 3).
Figure 3 shows images of non-agglomerated base mixture samples, before and after the carbothermal reduction step, their total magnetization and the morphologies of the metallic residue obtained.
Figure 4 shows the relationship between the residual mass after reduction and the metal iron content of the carbothermal reduction residue for Routes 2 and 3.
Figure 5 shows the metallic iron content obtained in relation to the microwave incidence time (with power of 1.0 kW) and the amount of carbon included in the base mixture prior to carbothermal reduction.
Figure 6 shows the metallic iron content obtained in relation to the specific energy (Gj/t product) and the amount of carbon contained in the base mixture before the carbothermal reduction in the microwave oven.
Figure 7 shows the XRD results of the residues obtained after carbothermal reduction (Routes 2 and 3) of agglomerated and non-agglomerated base mixture formulations, and the indication of total Fe content of the iron component of the base mixture prior to carbothermal reduction.
Figure 8 shows the XRD results of the residues obtained after carbothermal reduction (Route 3) of residual sludge formulations of non-agglomerated iron ore concentration and the indication of total Fe content of the ferrous component of the base mixture prior to carbothermal reduction.
Figure 9 illustrates a schematic representation of the semi-industrial microwave oven to be used over the carbothermal reduction step, in this case using base mixture as feed (Route 3).
DETAILED DESCRIPTION OF INVENTION
[0021] While this invention may be susceptible to different embodiments, preferred embodiments are shown in the drawings and the following thorough discussion, following the assumption that this disclosure is to be considered an exemplification of the invention principles, although not intended to limit this invention to what has been illustrated and described herein.
[0022] The matter required in this invention will henceforth be detailed for illustration purposes, and not exhaustively, since materials and methods disclosed herein may comprise different details and procedures, without departing from the scope of invention. Unless otherwise indicated, all parts and percentages disclosed below are by weight.
[0023] This invention refers to a process for obtaining high iron product as represented by the flowchart of Figure 1, which preferably starts by mixing at least 60 wt% iron ore fines; up to 30 wt% biomass; up to 15 wt% binders; up to 15 wt% nanomaterials; up to 15 wt% chemical additives and catalysts. More specifically, up to 20 wt% biomass, preferably pyrolyzed, may be used. This base mixture should be carried out in an intensive mixer.
[0024] Feedstock that can be used as sources of iron ore fines include sinter feed, pellet feed, or ultrafine iron ore tailings. The particle size of this material should be less than 10 mm, with d90 between 10 µm and 8 mm, and maximum humidity of 25%. The chemical composition should have the following characteristics: 30 to 68% iron (total Fe), 0.5 to 15% SiO2, 0.1 to 5.0% Al2O3, 0.001 to 0.1% P, 0.1 to 2% Mn, and 0.1 to 10% calcination loss.
[0025] The biomasses used can be from different sources, such as eucalyptus, elephant grass, residues such as sugarcane bagasse, among other biomasses and residues. Preferably the biomass should contain the following chemical composition: 0.5 to 25.0% ash; 1 to 80% volatile material; < 1% sulfur; and 20 to 80% fixed carbon. Biomass can also be used in pyrolyzed form, also called biocarbon.
[0026] Binders to be used include sodium silicate (solid and liquid state), pregelatinized cassava or corn starch, plant resins, polymers, and geopolymers. Binders are used along with chemical catalysts and nanomaterials, forming an additive binder mixture.
[0027] Chemical catalysts such as Ca, K, Na, Ni, Si, and W can be used to accelerate the rate of carbothermal reduction, as well as to ensure better homogeneity in microwave agglomerate heating.
[0028] The nanomaterials to be used can be selected from the group consisting of carbon nanotube, exfoliated graphite, functionalized micro-silicate, tubular nanosilica, tubular halloysite, carbon nanofiber, graphene, among others.
[0029] The chemical additives to be used in the coating process may be based on C, Al, Ni, ferruginous kaolinite, or other material with high reduction potential, such as bauxite, alumina, polymers, and latex. Also, if necessary, as feedstock in the production of self-reducing briquette (Route 1), fluxants based on calcium and dolomite can be used as additives.
[0030] As represented by the flowchart of Figure 1, after the intensive mixing step, the material that will follow Route 1 should go through the agglomeration step. The material should be agglomerated by mechanical processes (briquetting, extrusion, or pelletizing), as a means to provide sufficient green strength for handling, screening, and drying/curing.
[0031] As an alternative, the base mixture obtained in the intensive mixer may be subjected to a comminution process, in order to increase the specific surface and adhesion between particles. Preferably, the comminution should be carried out via pressing by means of roller press, roller crusher, or other comminution device in different quantities (partial or complete).
[0032] After the agglomeration step, the material should go through a granulometric classification step, preferably screening, such that the undersize (fraction < 5 mm) should return to the intensive mixer, and the oversize (fraction > 5 mm) should proceed to the drying/curing step. Preferably the drying/curing should be carried out in a dryer, in a microwave oven, or conventional oven by burning gases (including burning synthetic gas generated from the gasification of biomass), at a temperature in the range of 240 to 400 °C, in such a way as to remove excess humidity and also carry out the curing of the contained binder, aiming to provide sufficient strength for handling, storage, transport, and use with entry from the top, in blast furnaces.
[0033] The agglomerated product obtained in this route is considered a self-reducing agglomerate, and has about 6 to 20% carbon, and 40 to 60% total iron.
[0034] Still, as represented by the flowchart of Figure 1, after the intensive mixing step, the material that will follow Route 2 should also go through the agglomeration step. The material should be agglomerated by mechanical processes (briquetting, extrusion, or pelletizing).
[0035] As an alternative, the mixture obtained in the intensive mixer may be subjected to a comminution process, in order to increase the specific surface and adhesion between particles. Preferably, comminution should be carried out via pressing by means of roller press, roller crusher, or other comminution device in different quantities (partial or complete).
[0036] After the agglomeration step, the material should go through a carbothermal reduction step in a microwave oven or other type of oven, until reaching temperatures between 500 °C and 950 °C, depending on the degree of reduction intended, ranging from the prevalent formation of magnetite and/or maghemite, to the total, or close to the total, metallization of the iron oxides present in the base mixture. Optionally, the carbothermal reduction may be performed between 500 °C and 800 °C.
[0037] The microwave reduction can be performed in an equipment with power in the range of 0.6 kW to 10 kW for the frequencies of 2450 MHz, and power of up to 100 kW at the frequency of 915 MHz, and can be multiples of these powers for larger scales. A microwave equipment similar to the equipment described in patent documents BR102020012185-5 and BR102019023195-5 can be used, preferably presenting reduction of the carbothermal reduction chamber for inert gas injection, and inert gas confinement system, as demonstrated by Figure 2. Preferably, the inert gas used consists of nitrogen gas (N2).
[0038] After the carbothermal reduction step, the material advances to the coating application step, which aims to avoid reoxidation of the agglomerate surface layers by atmospheric oxygen, improve its physical resistance, as well as to weathering.
[0039] Optionally, an agglomeration step (briquetting, extrusion, or pelletizing) may be performed prior to the coating step. Said briquetting step may be carried out cold or warm and, if necessary, an additive binder may be used.
[0040] The agglomerated product obtained through Route 2 of this invention is pointed out as an alternative of high chemical, physical, and metallurgical quality for use in reduction and melting furnaces (Blast Furnace - BF and Melters such as the Electric Arc Furnace - EAF, for example). Such agglomerated products have a diameter of 8 to 150 mm, different geometries, total iron content above 60%, and carbon content below 5%. If the purpose is to obtain an agglomerate to be used in BF, feedstock and process parameters are used in such a way as to obtain a final agglomerate containing 60 to 95% of total iron. If the purpose is to obtain an agglomerate to be used in EAF, feedstock and process parameters are used in such a way as to obtain an agglomerate containing above 85% metallic iron.
[0041] Also as represented by the flowchart of Figure 1, after the intensive mixing step, the material that will follow Route 3 should go directly to the carbothermal reduction step in a microwave oven. Similarly to what happens in Route 2, microwave reduction can be performed in an equipment with power in the range from 0.6 kW to 10 kW for the frequencies of 2450 MHz, and power of up to 100 kW at the frequency of 915 MHz, and can be multiples of these powers for larger scales.
[0042] Optionally, the base mixture may be subjected to a comminution process, preferably carried out via pressing by means of roller press, roller crusher, or other comminution device in different quantities (partial or complete).
[0043] After the carbothermal reduction step, the material may be disaggregated, or not, depending on the physical conditions under which the product exits the microwave oven. The subsequent step consists of a solid-solid separation step targeted at increasing iron concentration, which may consist of a magnetic separation or gravitic separation. The low iron concentrate obtained should return to the intensive mixer while the iron-rich concentrate proceeds to the subsequent process steps.
[0044] The concentrate, which is in powder form, containing high iron content can already be considered a final product to be marketed, as it is a high metallization material (between 60% and 85% of total iron) that has ideal characteristics for use in smelters or other melting furnaces.
[0045] Optionally, the concentrate containing high iron content can proceed to an agglomeration step, which can be performed cold or warm and, if necessary, an additive binder can be used. Agglomeration allows obtaining a product with granulometry and high density format for transport and handling, in addition to increasing the protection against oxidation by the ambient atmosphere.
[0046] The agglomerate then proceeds to the coating application step, as occurs on Route 2, in such a way as to prevent the reoxidation of the agglomerate surface layers by atmospheric oxygen and improve its physical and weathering resistance.
[0047] Optionally, the material feeding the agglomeration step may come directly from carbothermal reduction, depending on the material characteristics after microwave oven reduction.
[0048] As occurring in Route 2, the agglomerate obtained through Route 3 of this invention is pointed out as an alternative of high chemical, physical, and metallurgical quality for use in reduction furnaces (Blast Furnace - BF and melters such as the Electric Arc Furnace - EAF, for example). The agglomerates obtained through Route 3 have more than 60% of total iron. If the purpose is to obtain an agglomerate to be used in BF, feedstock and process parameters are used in such a way as to obtain a final reduced agglomerate containing 60 to 95% of total iron. If the purpose is to obtain an agglomerate to be used in EAF, feedstock and process parameters are used in such a way as to obtain a final metallized agglomerate containing above 85% metallic iron.
[0049] As concerns meeting the physical quality specifications, agglomerates were subjected to laboratory tests to assess their mechanical strength. The parameters assessed were abrasion resistance, where the products presented results < 25%, drum resistance (> 75%), impact/fall resistance (> 75%), and compressive strength (dry and after exposure to water, > 150 daN). Regarding the chemical and metallurgical quality, tests were carried out to assess the degree of metallization with level depending on the feed and the purpose, whether it is metallization (> 50%) or concentration (0 and 10%).
[0050] Figure 3 shows images of samples before and after the carbothermal reduction step, obtained according to Route 3, showing the morphology of the formation of metallic iron after the reduction of the mixture by microwave. The results achieved, according to Figures 5 and 6, point out to a metallic Fe content of non-agglomerate, as well as of agglomerate (according to Route 2), in the range from 50 to 80%, for base mixtures with carbon content around 20%.
EXAMPLE
[0051] In order to evaluate the quality and performance of the products obtained through Route 3 of the present invention, an experiment was carried out by mixing 76% by mass of iron ore fines (FeT > 64.5% and granulometry < 325#) and 24% by mass of fine charcoal, derived from eucalyptus pyrolysis (Cfixed > 75%, granulometry < 1.0 mm), homogenized in an intensive mixer (Cfixed 20%). Carbothermal reduction was performed in a microwave oven, as shown in Figure 2, at 1000 W of power and frequency 2.45 GHz. The reduction occurred for 20 minutes, in an atmosphere inerted with N2.
[0052] The thin metallized product produced, as shown in Figure 3, had a metallic iron content of 76.7% and total iron of 89.9%, as revealed in the XRD result shown in the graph of Figure 7.
[0053] Thus, although only some embodiments of this invention have been shown, it is assumed that various omissions, substitutions, and changes may be made by one skilled in the art, without departing from the spirit and scope of this invention. The described embodiments are to be considered in all respects only as illustrative, and not exhaustively.
1. A process of obtaining high iron product from iron ore fines and biomass comprising the steps of:
a. mixing iron ore fines, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
b. performing at least one step out of the group consisting of agglomeration and carbothermal reduction;
c. performing at least one step out of the group consisting of solid-solid separation, carbothermal reduction, and agglomeration.
2. The process of claim 1, characterized in that there will be a further step of:
d. performing at least one step out of the group consisting of drying/curing and coating application.
d. performing at least one step out of the group consisting of drying/curing and coating application.
3. The process of claim 1, characterized in that, after the mixing step, a comminution step may be performed via pressing by means
of roller press, roller crusher, or another comminution device.
4. The process of claim 1, characterized in the steps of:
a. mixing iron ore fines, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
b. performing agglomeration via briquetting, pelletizing, or extrusion;
c. performing solid-solid separation via screening;
d. performing drying/curing.
5. The process of claim 1, characterized in the steps of:
a. mixing iron ore fines, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
b. performing agglomeration via briquetting, pelletizing, or extrusion;
c. performing carbothermal reduction;
d. performing coating application.
6. The process of claim 5, characterized in that, after the carbothermal reduction step, an additional agglomeration step may be performed
via briquetting, pelleting, or extrusion.
7. The process of claim 1, characterized in the steps of:
a. mixing iron ore fines, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
b. performing carbothermal reduction;
c. performing agglomeration via briquetting, pelletizing, or extrusion;
d. performing coating application.
8. The process of claim 7, characterized in that, after the carbothermal reduction step, a solid-solid separation step may be performed
via magnetic separation or gravitic separation.
9. The process of claim 1, characterized in the steps of:
a. mixing iron ore fines, biomass, binders, nanomaterials, additives, and catalysts in an intensive mixer;
b. performing carbothermal reduction;
c. performing solid-solid separation by means of magnetic separation or gravitic separation.
10. The process of claims 7 and 9, characterized in that, after the carbothermal reduction step, a disaggregation step may be performed.
11. The process of claim 1, characterized in that the carbothermal reduction is performed in a microwave oven or conventional oven
at temperatures in the range of 500 °C to 950 °C.
12. The process of claim 1, characterized in that the carbothermal reduction is performed in a microwave oven or conventional oven
at temperatures in the range of 500 °C to 950 °C.
13. The process of claim 2, characterized in that the drying/curing can be performed in a microwave oven, or conventional fuel-burning
oven, at temperatures in the range of 240 °C to 400 °C.
14. Process according to claim 1, characterized by using at least 60% by weight of iron ore fines with particle size less than 10 mm,
iron content (FeTotal) of 30 to 68%, selected from the group consisting of sinter feed, pellet feed, and
ultrafine iron ore tailings.
15. Process according to claim 1, characterized by using up to 30% by weight of biomass that can come from eucalyptus trees, elephant
grass, residues such as sugarcane bagasse, among others.
16. Process according to claim 1, characterized by using up to 20% by weight of biomass that can come from eucalyptus trees, elephant
grass, residues such as sugarcane bagasse, among others.
17. The process of claim 1, characterized in that the biomass may be used in pyrolyzed form.
18. The process of claim 1, characterized in that the biomass has 20% to 80% fixed carbon.
19. The process of claim 1, characterized by using up to 15% by weight of binders selected from the group consisting of sodium
silicate, pregelatinized cassava or corn starch, plant resins, polymers, geopolymers,
among others.
20. The process of claim 1, characterized by using up to 15% by weight of catalysts selected from the group consisting of Ca,
K, Na, Ni, Si, and W.
21. The process of claim 1, characterized by using up to 15% by weight of nanomaterials selected from the group consisting of
carbon nanotube, exfoliated graphite, functionalized micro-silicate, tubular nanosilica,
tubular halloysite, carbon nanofiber, graphene, among others.
22. Process according to claim 1, characterized by using up to 15% by weight of chemical additives that can be based on C, Al, Ni, ferruginous
kaolinite, or other material with high reduction potential, such as bauxite, alumina,
polymers, latex, among others.
23. The process of claim 1, characterized in that the chemical additives used may contain calcium and dolomite-based fluxants.
24. A high iron content agglomerated product obtained from iron ore and biomass fines
produced from the process described in claim 1, characterized by having chemical, physical, and metallurgical qualities suitable for use in reduction
furnaces (Blast Furnace) and having a diameter of 8 to 150 mm, 6 to 20% carbon and
40 to 60% total iron, being considered a self-reducing agglomerate.
25. A high iron content agglomerated product obtained from iron ore and biomass fines
produced from the process described in claim 1, characterized by having chemical, physical, and metallurgical qualities suitable for use in reduction
and melting furnaces (Blast Furnace - BF and Melters such as Electric Arc Furnace
- EAF, for example), having a diameter of 8 to 150 mm, total iron content above 60%,
carbon content below 5%, abrasion resistance < 25%, drum resistance > 75%, impact/fall
resistance > 75%, compressive strength > 150 daN, and metallization degree > 50%.
26. Agglomerated product according to claim 25, characterized by having 60 to 95% total iron if the product is earmarked for use in Blast Furnace
- BF.
27. Agglomerated product according to claim 25, characterized by having above 85% of metallic iron if the product is intended for use in Electric
Arc Furnace - EAF.
28. Product of high iron content obtained from iron ore and biomass fines produced from
the process described in claim 1, characterized by being in powder form and having chemical, physical, and metallurgical qualities suitable
for use in Smelters and other melting furnaces, as it is a material of high metallization
(between 60% and 85% of total iron).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description