Coked solid agglomerates and method for producing same
Coked solid agglomerates produced from biocarbon and mineral coal at controlled temperatures address the energy inefficiency and sustainability issues of existing methods, offering high yield and reduced emissions in steelmaking applications.
Patent Information
- Application Number
- JP2025528864
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-16
- Filing Date
- 2023-08-25
- Publication Date
- 2025-10-30
AI Technical Summary
Existing agglomeration methods in the steel industry, particularly those using coal briquettes, are energy-intensive and lack ecological sustainability, as they often require high temperatures and non-renewable materials.
The production of coked solid agglomerates using biocarbon, mineral coal, and a binder, subjected to pyrolysis at a controlled temperature range (700°C to 800°C), enhancing mechanical strength and adhesion while reducing energy consumption.
The method achieves high yield and energy savings, increasing ecological sustainability by using biocarbon and lowering CO2 emissions, with improved mechanical properties for use in steelmaking furnaces.
Smart Images
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Abstract
Description
[Technical Field]
[0001]
[0001] This invention relates to solid agglomerates, and more particularly to solid agglomerates for use in steelmaking furnaces. [Background technology]
[0002] One of the main functions of a metallurgical furnace is the reduction of iron, separating iron (Fe) from its ore (Fe2O3). This separation is carried out by chemical reduction, which involves separating the metal from its oxide, and is carried out using a reducing agent. This reducing agent is a material that, under operating conditions, must attract oxygen more than the metal to be reduced. The main reducing agent used in the iron and steel industry is coke, which is derived from mineral coal.
[0003]
[0003] The steel industry relies heavily on metallurgical coal, which accounts for a large portion of the final cost of the steel produced. Mineral coal for integrated coking steelmaking is called coking coal, which is an essential component in the reduction of iron ore to metallic iron by combining with oxygen to produce carbon dioxide, iron, and slag.
[0004]
[0004] The type of coal commonly used in steelmaking is bituminous coal (soft coal), which forms a solid mass when heated (coking coal); on the other hand, if it does not soften or agglomerate when heated, it is called non-coking coal.
[0005]
[0005] Today, the use of agglomerates in the steel industry is becoming increasingly common. Agglomeration consists of agglomerating fine granular materials with the aim of obtaining larger products through the use of binders. This process makes it possible to obtain, for example, high-quality metal agglomerates or coal briquettes using small pieces that would normally be discarded. In some cases, coal pellets may replace coking coal, and metal pellets may replace iron ore.
[0006]
[0006] Among the various agglomeration methods, coal briquetting techniques are gaining ground in the industry. This technique, which can be used for both mineral and vegetable coal, generally involves the following steps: (i) granulometric balancing of the coal or biomass particles, (ii) mixing with a binder (agglomerant), (iii) mechanical compression, and (iv) drying the briquettes. The following documents describe examples of coal briquettes and their respective manufacturing methods:
[0007]
[0007] For example, document US8585786B2 describes a method and system for briquetting a solid fuel such as coal, in which the solid fuel is transported through a continuous feed solid fuel treatment plant, treated with electromagnetic energy and briquettered after treatment.
[0008]
[0008] Document WO2014098413A1 describes coal briquettes and a method for producing the same. The method for producing coal briquettes includes the steps of (i) providing pulverized coal, (ii) mixing between 1 and 5 parts by weight of a hardener and between 5 and 15 parts by weight of a binder, per 100 parts by weight of the pulverized coal, to produce a mixture, and (iii) molding the mixture. In the pulverized coal providing step, the pulverized coal includes (i) more than 0% and not more than 50% by weight of low-rank coal, and (ii) the remaining coal ash. The low-rank coal has a volatile fraction (on an anhydrous basis) between 25% and 40% by weight and a crucible expansion number greater than 0 and less than 3.
[0009]
[0009] Document WO2013152959A1 describes a method for producing coal-containing briquettes, in which coal is mixed with a binder system with the introduction of steam, and the resulting mixture is pressed to form briquettes. At least one of the following steps is performed by direct or indirect interaction with superheated steam: (i) drying the carbon support before mixing; (ii) setting the temperature of the carbon support mixed with the binder system within a predetermined temperature range before mixing; and (iii) heat-treating the briquettes after pressing. The resulting residual steam is used as at least a portion of the steam introduced during mixing.
[0010]
[0010] Document AU2008203855B2 describes a method for forming briquettes comprising low-rank coal and aggregate material, characterized in that the method includes drying a low-rank coal feed to produce dry coal having a moisture content between 8% and 16% by weight, mixing the dry coal with aggregate material, and compressing the mixture of dry coal and aggregate material into briquettes.
[0011] As mentioned above, coal briquettes can be used in a method for reducing iron ore or its agglomerates in a steelmaking furnace. For example, document WO2011108466A1 describes a method for producing ferrous coke by carbonizing an agglomerate containing mineral coal and iron ore. This method produces ferrous coke, which is more reactive with CO2 in a blast furnace than the coke it contains. The ferrous coke production method in document WO2011108466A1 includes carbonizing a mixture of mineral coal and iron ore at a temperature of 800°C or higher to produce ferrous coke.
[0012]
[0012] The method in document WO2011108466A1 has been found to be ecologically unsustainable as it requires a large amount of energy to dry distill the aggregates and does not provide for the use of renewable carbon materials.
[0013] The present invention solves the above-mentioned problems in the prior art in a simple and efficient manner. Summary of the Invention
[0014] It is a primary object of the present invention to provide a coked solid agglomerate for use in a steelmaking furnace and a method for its production in which the coking process is carried out at a relatively low temperature.
[0015]
[0015] A second object of the present invention is to provide a coked solid agglomerate for use in steelmaking furnaces and a method for its production using a reasonable amount of biocarbon to increase the ecological sustainability of the fuel.
[0016]
[0016] To achieve the above object, the present invention provides coked solid agglomerates for use in steelmaking furnaces, comprising biocarbon, mineral coal, and at least one binder, wherein after the solid agglomerates are mechanically formed, they are subjected to a pyrolysis step at a temperature of at least 700°C and less than 800°C.
[0017]
[0017] The present invention further provides a method for producing coked solid agglomerates for use in steelmaking furnaces, the method comprising the steps of: (i) mixing biocarbon, mineral coal, and at least one binder; (ii) mechanically forming the mixture of biocarbon, mineral coal, and at least one binder to form solid agglomerates; and (iii) pyrolyzing the solid agglomerates at a temperature of 700°C or more and less than 800°C. DETAILED DESCRIPTION OF THE INVENTION
[0018]
[0018] First, please note that the following description is based on a preferred embodiment of the present invention. However, as will be apparent to those skilled in the art, the present invention is not limited to this particular embodiment.
[0019] The present invention provides a coked solid aggregate for use in steelmaking furnaces, the solid aggregate comprising in its composition biocarbon, mineral coal, and at least one binder. For purposes of this specification, biocarbon means any charcoal of plant origin produced according to substantially sustainable standards. Preferably, the biocarbon has a low inorganic content (less than 1%).
[0020]
[0020] After mechanical forming, the solid agglomerates are subjected to a pyrolysis process at a temperature above 700°C and below 800°C. This heat treatment cokes the carbonaceous materials in the mixture, increasing the interaction and adhesion between all components of the solid agglomerates and improving their mechanical strength. Furthermore, pyrolysis of the solid agglomerates promotes their drying and pre-reduction, increasing their calorific value and preparing them for use in steelmaking furnaces.
[0021] Preferably, the pyrolysis of the solid agglomerates is carried out in a rotating cylindrical reactor.
[0022]
[0022] Preferably, the solid aggregate of the present invention contains 10 to 75% by mass of biocarbon, more preferably 50 to 65% by mass of biocarbon.
[0023]
[0023] Preferably, the solid agglomerates of the present invention contain 25 to 90% by mass of mineral coal, more preferably 25 to 50% by mass of mineral coal.
[0024] Preferably, the solid agglomerates of the present invention contain 5 to 10% by weight of a binder, which functions to hold the compounds of the solid agglomerates together. The use of a binder also allows for the use of compounds with smaller particle sizes in the solid agglomerate composition.
[0025]
[0025] Optionally, the solid agglomerates of the present invention additionally contain 5 to 15 wt. % of an iron-based compound, such as iron oxide or metallic iron. Mixing the iron-based compound with the agglomerates produces iron-coke agglomerates. As is well known, due to the catalytic effect of the iron content of iron-coke, the reaction of carbonaceous materials begins at a lower temperature compared to conventional coke. Consequently, when iron-coke is used as a charge material in a steelmaking furnace, lowering the temperature of the heat storage zone can be expected to have a positive effect on the reducing agent ratio (RAR).
[0026]
[0026] The present invention also provides a method for producing coked solid agglomerates for use in steelmaking furnaces, the method comprising the steps of: (i) mixing biocarbon, mineral coal, and at least one binder; (ii) mechanically forming the mixture of biocarbon, mineral coal, and at least one binder to form solid agglomerates; and (iii) pyrolyzing the solid agglomerates at a temperature of at least 700°C and less than 800°C.
[0027]
[0027] Preferably, the mixing step is carried out using 10 to 75 mass % of biocarbon, and more preferably, the mixing step is carried out using 50 to 65 mass % of biocarbon.
[0028]
[0028] Preferably, the mixing step is carried out using 25 to 90% by mass of mineral coal, more preferably 25 to 50% by mass of mineral coal.
[0029]
[0029] Preferably, the mixing step is carried out using 5 to 10% by weight of the binder.
[0030] Optionally, the mixing step also involves mixing 5-15 wt. % of an iron-based compound, such as iron oxide or metallic iron, to form iron-coke agglomerates.
[0031] The solid agglomerates and their production method according to the present invention have a mass yield of 95%, whereas prior art agglomerates have a mass yield of about 70%. Furthermore, due to the temperature below 800°C, significant energy savings are achieved in the production method.
[0032] The coked solid agglomerates of the present invention can be used, for example, in blast furnaces, sintering furnaces and coking plants. The iron-containing solid agglomerates (ferrocoke) can be used, for example, to replace small coke in blast furnaces.
[0033]
[0033] Thus, as explained above, the present invention provides a coked solid agglomerate for use in steelmaking furnaces and a method for its production, in which the coking process is carried out at a relatively low temperature. Furthermore, a reasonable amount of biocarbon is used in the agglomerate and the production method, increasing the ecological sustainability of the fuel and reducing CO2 emissions.
[0034] Numerous variations within the scope of protection of this claim are permitted, which reinforces the fact that the present invention is not limited to the specific configurations / embodiments described above.
Claims
1. 1. A coked solid agglomerate for use in a steel furnace, the solid agglomerate comprising in its composition biocarbon, mineral coal and at least one binder, characterized in that said solid agglomerate is mechanically formed and then subjected to a pyrolysis step at a temperature of at least 700°C and less than 800°C.
2. 2. The solid aggregate according to claim 1, characterized in that it contains 10 to 75% by weight of biocarbon.
3. 3. Solid agglomerate according to claim 1 or 2, characterized in that it contains 25 to 90% by weight of mineral coal.
4. A solid agglomerate according to any one of claims 1 to 3, characterized in that it contains 5 to 10% by weight of a binder.
5. 5. Solid agglomerate according to any one of claims 1 to 4, characterized in that it additionally contains 5 to 15% by weight of an iron-based compound.
6. 6. The solid aggregate of claim 5, wherein the iron-based compound is at least one of iron oxide and metallic iron.
7. 1. A method for producing coked solid agglomerates for use in a steelmaking furnace, comprising: mixing biocarbon, mineral coal, and at least one binder; mechanically forming a mixture of biocarbon, mineral coal, and at least one binder to form a solid aggregate; pyrolyzing the solid agglomerates at a temperature of at least 700°C and less than 800°C.
8. 8. The method of claim 7, wherein the mixing step is carried out with 10 to 75% by weight of biocarbon.
9. 9. The method according to claim 7 or 8, characterized in that the mixing step is carried out with 25 to 90% by weight of mineral coal.
10. 10. The method according to any one of claims 7 to 9, characterized in that the mixing step is carried out with 5 to 10% by weight of binder.
11. 11. The method according to any one of claims 7 to 10, characterized in that the mixing step additionally comprises mixing 5 to 15% by weight of an iron-based compound.