Cold-pressed solid agglomerates and methods of making same

Abstract

The invention relates to cold-pressed solid agglomerates comprising a DRI powder or a pre-reduced briquette powder. In this context, the present invention presents universal agglomerates that can be used in blast furnaces, alkaline oxygen converters (BOFs) and electric arc furnaces (EAFs). For this purpose, the agglomerates of the invention comprise (i) 80% to 90% by mass of a DRI powder or a pre-reduced briquette powder, (ii) 5% to 10% by mass of at least one binder, and (iii) 5% to 10% by mass of charcoal. According to the invention, the method for producing cold-pressed solid agglomerates comprises the following steps: (i) mixing 80% to 90% by mass of a DRI powder or a pre-reduced briquette powder, 5% to 10% by mass of at least one binder and 5% to 10% by mass of carbon; and (ii) cold pressing the mixture of the DRI powder or the pre-reduced briquette powder, the at least one binder and the charcoal.

Description

Technical Field

[0001] This invention relates to solid agglomerates. More specifically, this invention relates to cold-pressed solid agglomerates comprising DRI or pre-reduced briquetted powder. Background Technology

[0002] Steel and its alloys hold fundamental importance in modern society, making the steelmaking industry crucial for economic and sustainable growth. However, the substantial amount of waste generated during steel production processes requires special attention from researchers, as it is clearly necessary to treat and / or reuse this waste to reduce environmental impact and the depletion of natural resources. Circular economy (CE) is one of the key pillars for achieving sustainability in the steel industry. Theoretically, a circular economy is an economic system designed to maximize resource extraction and minimize waste disposal. In this sense, CE enables the addition of value to steelmaking waste by reusing it within the process itself.

[0003] Traditional steel production routes use blast furnaces (BF) as reduction reactors to obtain iron. Alternative technologies that reduce energy use and carbon emissions are based on iron production via direct reduction. The direct reduction product, known as sponge iron or DRI (direct reduced iron), is designed for use in steelmaking equipment that produces steel in basic oxygen converters (BOF) or electric arc furnaces (EAF).

[0004] Direct reduction products can be briquetted to obtain hot-pressed iron (HBI), which consists of resistant, low-porosity agglomerates capable of long-distance transport for subsequent processes. During the production and processing of DRI, powders primarily composed of metallic iron, along with iron oxides and gangue are generated.

[0005] Using the AF-BOF route generates an average of 500 kg of waste per ton of molten steel produced. Additionally, approximately 185 kg of waste is generated per ton of molten steel obtained from an electric arc furnace. If all these steelmaking byproducts are disposed of separately in landfills and dams, the environmental impact will inevitably be significant. Therefore, it is extremely important to consider different technological solutions aimed at internally reusing this waste in order to achieve sustainability in the steelmaking industry.

[0006] Currently, DRI powder is agglomerated and "reused / recycled" in pig iron or steel production equipment. These materials have limited and exclusive uses. In some cases, briquettes are intended for use in steel production in electric or oxygen furnaces, where iron is melted and incorporated, and components are separated and removed in the slag. In other cases, powder produced in direct reduction units is briquetted in situ and used in the DRI production process itself, as if the material were recycled. Lime, molasses, and sodium silicate are commonly used as binders in the production of agglomerates, and their size and shape are similar to those of HBI. The agglomeration process used is simple and focuses on reducing the surface area per volume of material, reducing re-oxidation capacity, and recycling the material. However, some parameters, such as powder particle size analysis, the use of alternative binders, and the geometry of the agglomerates, limit the physicochemical and mechanical properties of the product. These limitations prevent the material from being used in more general ways, such as in iron-steel conversion processes, reduction and melting furnaces, induction furnaces, etc.

[0007] The present invention addresses the problems of the prior art described above in a simple and effective manner. Summary of the Invention

[0008] The first objective of this invention is to provide cold-pressed solid agglomerates and a method for manufacturing the same, which enables the reuse of such waste generated in the steelmaking industry.

[0009] A second object of the present invention is to provide a cold-pressed solid agglomerate that can be used in blast furnaces, oxygen converters (BOF), electric arc furnaces (EAF), and self-reducing shaft furnaces or melting furnaces (melting furnaces and smelting furnaces).

[0010] A third objective of this invention is to provide cold-pressed solid agglomerates and methods for producing them, which reduce carbon emissions and improve the energy efficiency of steel industry processes.

[0011] To achieve the above objectives, the present invention provides a cold-pressed solid agglomerate comprising (i) 80% to 90% by weight of DRI powder or pre-reduced briquette powder, (ii) 5% to 10% by weight of at least one binder, and (iii) 5% to 10% by weight of charcoal.

[0012] The present invention further provides a method for manufacturing cold-pressed solid agglomerates, the method comprising the steps of: (i) mixing 80% to 90% by weight of DRI powder or pre-reduced briquette powder, 5% to 10% by weight of at least one binder, and 5% to 10% by weight of charcoal, and (ii) cold-pressing the mixture of DRI powder, at least one binder and charcoal. Detailed Implementation

[0013] As a preliminary point, it should be emphasized that the following description is based on a preferred embodiment of the invention. However, it will be apparent to any person skilled in the art that the invention is not limited to this specific embodiment.

[0014] This invention provides a cold-pressed solid agglomerate and a method for manufacturing the same. The cold-pressed solid agglomerate of this invention comprises:

[0015] 80% to 90% by weight of DRI powder or pre-reduced briquetted powder;

[0016] At least one adhesive, comprising 5% to 10% by weight;

[0017] 5% to 10% charcoal by weight.

[0018] Preferably, the at least one adhesive may contain at least one of the following: water, starch, phenolic resin, lime, molasses, sodium silicate, and sodium hydroxide.

[0019] Preferably, the at least one adhesive is obtained by combining water, starch, and sodium hydroxide in the following mass ratios:

[0020] Water: 83% to 87.5%;

[0021] Starch: 12% to 16%;

[0022] Sodium hydroxide: 0.5% to 1%.

[0023] Preferably, the at least one adhesive may be organic, miscible in water, and fluid at room temperature.

[0024] Preferably, the agglomerates of the present invention comprise at least one liquid additive added to the mixture, which provides operational convenience. Optionally, a crystallizer protective slag agent (e.g., calcium oxide) can be used to impart greater fluidity to the slag formed in the steel furnace, wherein the agglomerates of the present invention will also be used.

[0025] A method for manufacturing a cold-pressed solid agglomerate according to the present invention comprises the following steps: (i) mixing 80% to 90% by weight of DRI powder, 5% to 10% by weight of at least one binder and 5% to 10% by weight of charcoal; and (ii) cold-pressing the mixture of DRI powder, at least one binder and charcoal.

[0026] Preferably, the method for manufacturing cold-pressed solid agglomerates according to the invention controls the particle size analysis of DRI powder or pre-reduced briquette powder by pulverizing the material in at least one crusher and / or mill and separating the material in at least one sieve, separating the DRI powder or pre-reduced briquette powder into particles within the optimized particle size analysis curve of the process.

[0027] Optionally, to increase the iron concentration of the agglomerates, a magnetic separator may be used during particle size analysis control.

[0028] Preferably, the method for producing the cold-pressed solid agglomerates according to the invention includes a step of adding an additive to the mixture prior to the step of cold-pressing the mixture. As previously mentioned, the additive may be, for example, a crystallizer protective slag agent (e.g., calcium oxide) to improve the fluidity of the slag formed in the steelmaking furnace, wherein the agglomerates of the invention will also be used.

[0029] Preferably, the method for producing cold-pressed solid agglomerates includes a step of drying the solid agglomerates after the step of cold-pressing the mixture.

[0030] In this way, it is observed that the present invention provides a cold-pressed solid agglomerate comprising DRI powder and a method for manufacturing the same, which enables the reuse of such waste generated in the steel industry. The DRI powder is then reused, allowing steel production to be carried out in a wider range of reactors, such as blast furnaces, oxygen converters (BOF), electric arc furnaces (EAF), and self-reducing shaft furnaces or smelting furnaces (smelting furnaces and melting furnaces).

[0031] In this way, waste from the steel industry is reused to improve the energy efficiency of the process, reduce production costs and the impact of carbon emissions, especially due to the presence of carbon (biocarbon) in the agglomerate composition of the present invention.

[0032] Many variations are permissible that affect the scope of protection of this application. In this way, it is emphasized that the invention is not limited to the specific configurations / implementations described above.

Claims

1. A cold-pressed solid agglomerate, characterized in that... It contains: 80% to 90% by weight of DRI powder or pre-reduced briquetted powder; At least one adhesive, comprising 5% to 10% by weight; 5% to 10% charcoal by weight.

2. The aggregate according to claim 1, characterized in that... The at least one adhesive comprises at least one of the following: water; starch; Phenolic resin; lime; Molasses; Sodium silicate; Calcium oxide; Sodium hydroxide.

3. The aggregate according to claim 1 or 2, characterized in that... The at least one adhesive is obtained by combining water, starch, and sodium hydroxide in the following mass ratio: Water: 83% to 87.5%; Starch: 12% to 16%; Sodium hydroxide: 0.5% to 1%.

4. The aggregate according to any one of claims 1 to 3, characterized in that The at least one adhesive is miscible in water and fluids at room temperature.

5. The aggregate according to any one of claims 1 to 4, characterized in that... It further contains at least one additive.

6. The aggregate according to any one of claims 1 to 5, characterized in that... The particle size analysis of the mixtures used followed the optimized distribution curve based on the Alfred model.

7. A method for manufacturing cold-pressed solid agglomerates, characterized in that... It includes: Mix 80% to 90% by weight of DRI powder or pre-reduced briquette powder, 5% to 10% by weight of at least one binder, and 5% to 10% by weight of charcoal. and A mixture of DRI powder or pre-reduced briquetted powder, at least one binder, and charcoal is cold-pressed.

8. The method according to claim 7, characterized in that... The steps for controlling the particle size analysis of the DRI powder include: Crushing materials in at least one crusher and / or mill; and The pulverized material is separated in at least one sieve.

9. The method according to claim 7 or 8, characterized in that... It includes the step of adding additives to the mixture prior to the step of cold pressing the mixture.

10. The method according to any one of claims 7 to 9, characterized in that... It further includes a step of drying or curing the solid agglomerates after the step of cold pressing the mixture.