Cold-formed solid aggregates and methods for producing the same

Abstract

The present invention relates to cold-formed solid aggregates comprising DRI granules or pre-reduced briquette granules. In this context, the present invention presents a multipurpose aggregate that can be used in blast furnaces, basic oxygen furnaces (BOFs), and arc electric furnaces (EAFs). For this purpose, the aggregate of the present invention comprises (i) 80-90% by mass of DRI granules or pre-reduced briquette granules, (ii) 5-10% by mass of at least one binder, and (iii) 5-10% by mass of carbon. According to the present invention, a method for producing a cold-formed solid aggregate comprises (i) mixing 80-90% by mass of DRI granules or pre-reduced briquette granules, 5-10% by mass of at least one binder, and 5-10% by mass of carbon; and (ii) cold-forming the mixture of DRI granules or pre-reduced briquette granules, at least one binder, and carbon.

Description

Field of the Invention

[0001]

[0001] The present invention relates to solid aggregates. More specifically, the present invention relates to cold-compacted solid aggregates containing DRI or pre-reduced briquette fines. Background of the Invention

[0002]

[0002] Steel and its alloys are fundamentally important in modern society, and the steelmaking sector has become essential for economic and sustainable growth. However, the large amount of waste generated during the iron and steel manufacturing process requires special attention from researchers because the need to treat and / or reuse this waste is clear in order to reduce environmental impact and natural resource consumption. To achieve sustainability in the iron and steel industry, circular economy (CE) is one of the important pillars. Theoretically, circular economy is an economic system designed to maximize resource extraction and minimize waste disposal. In this sense, CE enables the value improvement of steelmaking waste by reusing it within the process itself.

[0003]

[0003] Document IN201921038999 teaches direct reduced iron (DRI) briquettes and a method for agglomerating DRI briquettes for effective use in steelmaking. The method of this invention provides for briquetting DRI briquettes into high-density metallized briquettes for use as a coolant in primary steelmaking at BOF. Molasses and slaked lime (calcium hydroxide) are used as binder and hardener, respectively, with selective mixing and pressurization in the briquetting process, followed by hardening.

[0004]

[0004] Reference US7896963 teaches self-reducing and cold-bonded pellets, as well as methods for manufacturing them for casting a wide variety of steels. Self-reducing and cold-bonded pellets comprise iron ore concentrate, a carbonaceous reducing agent, and pulverized Portland cement clinker having specific requirements as a binder. These components are combined to form a mixture. The pellets are manufactured by placing the mixture into a pelletizing disc or rotating drum and adding water.

[0005]

[0005] Conventional steelmaking routes use blast furnaces (BF) as reduction reactors to obtain iron. Alternative technologies to reduce energy use and carbon emissions are based on iron production by direct reduction. The direct reduction product is called sponge iron or DRI (direct reduced iron), which is for steel plants to produce steel in basic oxygen furnaces (BOF) or electric arc furnaces (EAF).

[0006]

[0006] The direct reduction product can be briquetted to obtain HBI (hot briquetted reduced iron), which consists of resistant and low-porosity aggregates that can be transported over long distances for use in subsequent processes. During the production and handling of DRI, fines mainly composed of metallic iron, as well as iron oxide and gangue, are generated.

[0007]

[0007] Using the AF-BOF route generates an average of 500 kg of waste per ton of molten steel produced. Furthermore, approximately 185 kg of waste is generated per ton of molten steel obtained from the arc electric furnace. If all of this steelmaking by-product were simply disposed of in landfills and dams, the environmental impact would undoubtedly be significant. Therefore, to achieve sustainability in the steelmaking industry, it is crucial to consider different technological solutions aimed at internally reusing this waste.

[0008]

[0008] Currently, DRI granules are agglomerated and "reused / recycled" in pig iron or steel manufacturing plants. These materials are for limited purposes and are proprietary. In some cases, the briquettes are intended for use in steelmaking in electric or oxygen furnaces, where the iron is melted, incorporated, and its components separated and removed into the slag. In other cases, granules produced in direct reduction plants are briquetteed on-site and used in the DRI manufacturing process itself, as if the material were being recycled. For agglomeration, lime, molasses, and sodium silicate are commonly used as binders, 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 unit volume of the material, reducing its re-oxidation capacity, and recycling the material. However, certain parameters, such as the granule size distribution, the use of alternative binders, and the agglomeration structure, can limit the physicochemical and mechanical properties of the product. These limitations prevent the material from being used in more versatile ways, such as in iron-to-steel conversion processes, reduction and melting furnaces, induction furnaces, and others.

[0009]

[0009] The present invention proposes a simple and efficient method to solve the problems of the existing technology described above. [Overview of the project]

[0010]

[0010] The first objective of the present invention is to provide a cold-headed solid aggregate and a method for producing the same that can be reused as waste generated in the steelmaking industry.

[0011]

[0011] A second objective of the present invention is to provide cold-formed solid aggregates that can be used in blast furnaces, oxygen converters (BOF), arc electric furnaces (EAF), and self-reducing shaft furnaces or melting furnaces (melting furnaces and blast furnaces).

[0012]

[0012] A third objective of the present invention is to provide cold-formed solid aggregates and methods for producing the same that reduce carbon emissions and increase energy efficiency in steel industry processes.

[0013]

[0013] To achieve the above objectives, the present invention provides a cold-formed solid aggregate comprising (i) 80-90% by mass of DRI granules or pre-reduced briquette granules, (ii) 5-10% by mass of at least one binder, and (iii) 5-10% by mass of carbon.

[0014]

[0014] The present invention provides a method for producing cold-formed solid aggregates, further comprising: (i) mixing 80-90% by mass of DRI granules or pre-reduced briquette granules, 5-10% by mass of at least one binder, and 5-10% by mass of carbon; and (ii) cold-forming the mixture of DRI granules, at least one binder, and carbon. Detailed description of the invention

[0015]

[0015] It should be emphasized that the following description is based on preferred embodiments of the present invention. However, as will be apparent to those skilled in the art, the present invention is not limited to these particular embodiments.

[0016]

[0016] The present invention provides cold-formed solid aggregates and a method for producing them. The cold-formed solid aggregates of the present invention are 80 to 90 mass% of DRI fines or pre-reduced briquette fines; 5 to 10 mass% of at least one binder; 5 to 10 mass% of carbon and contains.

[0017]

[0017] Preferably, at least one binder may contain at least one of water, starch, phenolic resin, lime, molasses, sodium silicate, and sodium hydroxide.

[0018]

[0018] Preferably, at least one binder is water, starch, and sodium hydroxide in the following mass ratios: Water: 83 to 87.5%; Starch: 12 to 16%; Sodium hydroxide: 0.5 to 1% obtained by combining.

[0019]

[0019] Preferably, at least one binder may be an organic substance, miscible with water, and a fluid at room temperature.

[0020]

[0020] [[ID=Some]]Preferably, the agglomerates of the present invention contain at least one liquid additive added to the mixture, which provides operational convenience. Optionally, a casting flux agent, such as calcium oxide, may be used to impart greater fluidity to the slag formed in the steel furnace where the agglomerates of the present invention are also used.

[0021]

[0021] A method for producing cold-compacted solid agglomerates according to the present invention includes: (i) a step of mixing 80 to 90 mass% of DRI fines, 5 to 10 mass% of at least one binder, and 5 to 10 mass% of carbon; (ii) a step of cold-compacting the mixture of DRI fines, at least one binder, and carbon.

[0022]

[0022] Preferably, the method for manufacturing the cold-pressed solid aggregate according to the present invention comprises crushing the material in at least one crusher and / or mill, separating it with at least one sieve, and separating the DRI fines or pre-reduced briquette fines into particles within the optimal particle size distribution curve of the method, thereby controlling the particle size distribution of the DRI fines or pre-reduced briquette fines.

[0023]

[0023] Optionally, for the purpose of increasing the iron concentration of the aggregate, the particle size distribution control process may include the use of a magnetic separator.

[0024]

[0024] Preferably, the method for manufacturing the cold-pressed solid aggregate according to the present invention includes a step of adding an additive to the mixture prior to the step of cold-pressing the mixture. As described above, for the purpose of improving the fluidity of the slag formed in the steelmaking furnace in which the aggregate of the present invention is also used, the additive may be, for example, a casting flux agent, such as calcium oxide.

[0025]

[0025] Preferably, the method for manufacturing the cold-pressed solid aggregate includes a step of drying the solid aggregate after the step of cold-pressing the mixture.

[0026]

[0026] Thus, it is observed that the present invention provides a cold-pressed solid aggregate containing DRI fines and a method for manufacturing the same, which can reuse such waste generated in the steel industry. The DRI fines are then reused so that iron and steel production can be carried out in a wider range of reactors, such as blast furnaces, basic oxygen furnaces (BOF), electric arc furnaces (EAF), and self-reducing shaft furnaces or smelting furnaces (smelting furnaces and blast furnaces).

[0027]

[0027] Thus, the waste from the steel industry is reused to increase the energy efficiency of the process and reduce the impact caused by manufacturing costs and carbon emissions, particularly due to the presence of carbon (bio-carbon) in the composition of the aggregate of the present invention.

[0028]

[0028] A great many modifications are permissible that affect the scope of protection of this application. Thus, it is emphasized that the present invention is not limited to the specific configurations / embodiments described above.

Claims

1. 80-90% by mass of DRI granules or pre-reduced briquette granules; 5 to 10% by mass of at least one binder; 5-10% by mass of carbon A cold-formed solid aggregate characterized by containing the following:

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

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

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

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

6. The aggregate according to any one of claims 1 to 5, characterized in that the particle size distribution of the composite material used follows an optimal distribution curve according to the Alfred model.

7. A method for producing cold-formed solid aggregates, wherein the previous method is A mixture comprising 80-90% by mass of DRI granules or pre-reduced briquette granules, 5-10% by mass of at least one binder, and 5-10% by mass of charcoal; Cold pressing a mixture of DRI granules or pre-reduced briquette granules, at least one binder, and charcoal. A method characterized by including

8. The process of controlling the particle size distribution of the DRI granules is as follows: The material is crushed in at least one crusher and / or mill; The pulverized material is separated using at least one sieve. The method according to claim 7, characterized by including

9. The method according to claim 7 or 8, characterized in that the method includes a step of adding an additive to the mixture prior to the step of cold-forging the mixture.

10. The method according to any one of claims 7 to 9, characterized in that the method further comprises a step of drying or hardening the solid aggregate after a step of cold-pressing the mixture.

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