Solid carbonized briquette and method for producing same

Abstract

The invention relates to a carbonized solid mass for a blast furnace, comprising in the composition: at least one carbon source (10); at least one calcium source (11); and at least one binder (12); wherein, after the mechanical shaping (200) of the solid mass, the mass is subjected to a pyrolysis step (400) at a temperature greater than or equal to 600 DEG C and less than 800 DEG C; wherein the solid mass comprises 25 to 35 mass% of at least one calcium source (11). The invention also relates to a method for producing the proposed solid mass.

Description

[0001] Supplementary certificate of BR102022023262-8, filed on November 16, 2022. Technical Field

[0002] The present invention relates to solid agglomerates (also known as solid aggregates or solid sintered blocks). More specifically, the present invention relates to solid agglomerates for a blast furnace and a method for manufacturing solid carbonized agglomerates for a blast furnace. Background Art

[0003] One of the main functions of a metallurgical furnace is to reduce iron, in which the metal is separated from its oxide. In the case of iron, it is usually an ore rich in Fe2O3, which is converted into Fe. This separation occurs by means of 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 must be more attractive to oxygen than the metal to be reduced under the operating conditions. The main source of reducing agent used in the steel industry is coke (which comes from mineral coal).

[0004] The steel industry heavily relies on metallurgical coal, which accounts for a large part of the final cost of the steel produced. The mineral coal used for integrated coke-making and steel-making is called coking coal, which is essential for the manufacture of coke and in turn indispensable for reducing iron ore to metallic iron in a blast furnace. In this process, the fuel combines with oxygen to form carbon dioxide, which converts iron oxide into iron and separates it from the slag.

[0005] Today, the use of agglomerates in the steel industry is becoming increasingly common. The agglomeration process involves grouping fine-grained materials, with the aim of obtaining a larger product by using a binder. Through this process, it is possible to obtain, for example, high-quality metal agglomerates or briquettes from small fractions that are usually discarded. In some cases, coal pellets can replace coking coal and metal pellets can replace iron ore.

[0006] Among different agglomeration processes, the briquetting technology for coal has made progress in the industry. This technology (which can be used for coal and charcoal) generally involves the following steps: (i) particle size balancing of coal or biomass particles; (ii) mixing of a binder (agglomerant); (iii) mechanical compaction; and (iv) drying of the briquettes. The following documents describe examples of coal briquetting and its corresponding production process.

[0007] For example, the document US8585786B2 describes a method and system for briquetting solid fuels such as coal. In this document, the solid fuel is conveyed through a continuous-feed solid fuel processing device, treated with electromagnetic energy, and briquetted after treatment.

[0008] The document WO2014098413A1 describes a coal briquette and a method for manufacturing the same. This method for manufacturing a coal briquette includes the following steps: (i) supplying pulverized coal; (ii) producing a mixture obtained by mixing 1 to 5 parts by weight of a hardening agent and 5 to 15 parts by weight of a binder with respect to 100 parts by weight of the pulverized coal; and (iii) shaping the mixture. In the pulverized coal supply stage, the pulverized coal includes (i) low-grade coal in an amount greater than 0 and not greater than 50% by weight and (ii) the balance being coal ash. The low-grade coal has a volatile portion (dry basis) between 25% and 40% by weight and has a crucible swelling number greater than 0 and less than 3.

[0009] The document WO2013152959A1 describes a method for producing coal-containing briquettes, in which coal is mixed with a binder system in the presence of introduced steam, and the resulting mixture is subjected to pressing to form briquettes. Here, at least one of the following steps is carried out by means of direct or indirect interaction with superheated steam: (i) drying the carbon carrier before mixing, (ii) setting the temperature of the carbon carrier to be mixed with the binder system within a predetermined temperature range before mixing, (iii) heat-treating the briquettes after pressing. The resulting residual steam is used as at least part of the steam introduced during mixing.

[0010] The document AU2008203855B2 describes a method for forming briquettes containing low-rank coal and aggregates, characterized by the fact 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 the aggregates; and compacting the dry coal and aggregates mixture 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, the document WO2011108466A1 describes a method for producing ferro-coke by carbonizing agglomerates containing mineral coal and iron ore. This method produces ferro-coke that has a higher reactivity with CO2 in a blast furnace than the coke contained therein. The ferro-coke production method in WO2011108466A1 includes carbonizing a mixture composed of coal and iron ore at a temperature above 800 °C to produce ferro-coke.

[0012] The method in document WO2011108466A1 is ultimately not ecologically sustainable because it requires a relatively large amount of energy to carbonize the agglomerates and does not provide for the use of renewable carbonaceous materials.

[0013] In addition, the agglomerates in the prior art have difficulties in their production during the coking stage. The coking of these agglomerates is usually carried out in a coking apparatus (which is a silicon carbide refractory). In this case, the iron oxides present in the agglomerates react with the silicon oxides from the coking apparatus and form a low-melting point phase that corrodes the refractory, thus posing an operational hazard.

[0014] In addition, the agglomerates of the prior art only catalyze the gasification reaction (Boudouard reaction) of the agglomerates in a blast furnace at high temperatures, which means that greater energy consumption is required to reach these temperatures.

[0015] The present invention solves the above problems in the prior art in a simple and efficient manner. Summary of the Invention

[0016] Object of the Invention

[0017] The first object of the present invention is to provide a solid carbonized agglomerate for a blast furnace and a method for manufacturing the same, wherein the carbonization method is carried out at a relatively low temperature.

[0018] The second object of the present invention is to provide a solid carbonized agglomerate for a blast furnace and a method for manufacturing the same, which combines the catalysis of a calcium source and an iron source (such as residues).

[0019] The third object of the present invention is to provide a solid carbonized agglomerate for a blast furnace and a method for manufacturing the same, which uses a reasonable amount of biocarbon, thereby improving the ecological sustainability of the fuel.

[0020] The fourth object of the present invention is to provide a solid carbonized agglomerate for a blast furnace and a method for manufacturing the same, which does not react with the refractory in the coking apparatus, thereby improving the safety of agglomerate production. Summary of the Invention

[0022] To achieve the above objects, the present invention provides a carbonized solid agglomerate for a blast furnace, the composition of which comprises: at least one carbon source; at least one calcium source; and at least one binder; wherein, after the mechanical forming of the solid agglomerate, the solid agglomerate is at a temperature greater than or equal to 600 °C and less than 800 °C; and wherein the solid agglomerate contains 25 to 35% by mass of at least one calcium source.

[0023] In some embodiments, at least one carbon source is at least one of the following: biochar, coal, and / or metallurgical coal.

[0024] In some embodiments, at least one calcium source is a calcium oxide source from at least one of the following: limestone or calcium-containing steel scrap.

[0025] In some embodiments, at least one binder is an organic binder.

[0026] In some embodiments, the solid agglomerate comprises 60 to 90% by mass of a carbon source.

[0027] In some embodiments, the carbon source comprises up to 70% by mass of biochar and between 30 and 100% by mass of coal.

[0028] In some embodiments, the solid agglomerate comprises 5 to 10% by mass of at least one binder.

[0029] In some embodiments, the solid agglomerate comprises 5 to 15% by mass of an iron-based compound, such as iron oxide or metallic iron.

[0030] The present invention also provides a method for manufacturing a solid carbonized agglomerate for a blast furnace, the method comprising the steps of: mixing at least one carbon source, at least one calcium source, and at least one binder; mechanically forming the mixture of the at least one carbon source, at least one calcium source, and at least one binder to form a formed solid agglomerate; and pyrolyzing the formed solid agglomerate at a temperature greater than or equal to 600 °C and less than 800 °C; wherein the solid agglomerate comprises 25 to 35% by mass of at least one calcium source.

[0031] In some embodiments, at least one carbon source is at least one of the following: biochar, coal, and / or metallurgical coal; and mixing comprises: mixing 60 to 90% by mass of the carbon source.

[0032] In some embodiments, the method comprises forming the carbon source using up to 70% by mass of biochar and between 30 and 100% by mass of coal.

[0033] In some embodiments, mixing comprises mixing 5 to 10% by mass of the at least one binder.

[0034] In some embodiments, mixing comprises mixing 5 to 15% by mass of an iron-based compound, such as iron oxide or metallic iron.

[0035] In some embodiments, the method further comprises, after the mechanical forming step, drying the formed agglomerate in an oven at 105 °C for two hours, wherein the humidity inside the oven is less than 1%. Description of the Drawings

[0036] The following detailed description refers to the accompanying drawings and their corresponding reference numerals.

[0037] Figure 1 A flowchart illustrating a method of manufacturing solid carbonized agglomerates according to an embodiment of the present invention is shown. Detailed Description

[0038] First, it should be noted that the following description will be 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.

[0039] The present invention provides a method of manufacturing solid carbonized agglomerates for a blast furnace, characterized by the fact that the method comprises the steps of: mixing at least one carbon source 10, at least one calcium source 11 and at least one binder 12; mechanically shaping 200 the mixture of the at least one carbon source 10, at least one calcium source 11 and at least one binder 12 to form a shaped solid agglomerate 20; and pyrolyzing 400 the shaped solid agglomerate 20 at a temperature greater than or equal to 600 °C and less than 800 °C; wherein the solid agglomerate contains 25 to 35% by mass of at least one calcium source 11.

[0040] It should be noted that this registration certificate relates to improvements in solid carbonized agglomerates and the method of manufacturing them as described in BR102022023262-8, which will be explained below for a better understanding of the present invention.

[0041] Solid Mass Coked at Low Temperature

[0042] A coked solid agglomerate for a steelmaking furnace is described, which contains biochar, mineral coal and at least one binder. For the purposes of this specification, biochar means any charcoal of plant origin produced according to substantially sustainable criteria. Preferably, such biochar has a low inorganic content (less than 1%).

[0043] Once mechanically shaped, the solid agglomerate undergoes a pyrolysis process at a temperature greater than or equal to 700 °C and less than 800 °C. This heat treatment cokes the carbonaceous materials in the mixture and increases the interaction and anchoring between all components of the solid agglomerate, thus enhancing its mechanical strength. In addition, the pyrolysis of the solid agglomerate promotes its drying and pre-reduction, thereby increasing its calorific value and preparing it for use in a steelmaking furnace.

[0044] Preferably, the pyrolysis of the solid agglomerate is carried out in a rotating cylindrical reactor.

[0045] Preferably, the solid agglomerate contains 10 to 75% by mass of biochar. More preferably, the solid agglomerate contains 50 to 65% by mass of biochar.

[0046] Preferably, the solid agglomerate contains 25 to 90% by mass of coal. More preferably, the solid agglomerate contains 25 to 50% by mass of coal.

[0047] Preferably, the solid agglomerate contains 5 to 10% by mass of a binder, which has the function of keeping the compounds in the solid agglomerate bound together. The use of the binder also allows the use of smaller particle-sized compounds in the composition of the solid agglomerate.

[0048] Optionally, the solid agglomerate also contains 5 to 15% by mass of an iron-based compound, such as iron oxide or metallic iron. The iron source used is preferably steelmaking waste, such as sludge (also known as metal chips) from the steelmaking process. Mixing the iron-based compound with the agglomerate produces an iron-containing agglomerate. As is well known, due to the catalytic action of the iron component of the iron-containing agglomerate, the reaction of the carbonaceous material starts at a lower temperature (compared to conventional coke), and as a result, a reduction effect can be expected, and as a result, when using the iron-containing agglomerate as a charge in a steelmaking furnace, a reduction effect on the reductant ratio (RAR) can be expected by reducing the temperature in the regenerative heating zone.

[0049] Also described is a method for manufacturing a solid coking agglomerate for a steelmaking furnace, comprising the steps of: (i) mixing biochar, coal, and at least one binder, (ii) mechanically forming the mixture of biochar, coal, and at least one binder to form a solid agglomerate, and (iii) pyrolyzing the solid agglomerate at a temperature greater than or equal to 700 °C and less than 800 °C.

[0050] Preferably, the mixing stage is carried out using 10 to 75% by mass of biochar. More preferably, the mixing stage is carried out using 50 to 65% by mass of biochar.

[0051] Preferably, the mixing stage is carried out using 25 to 90% by mass of coal. More preferably, the mixing stage is carried out using 25 to 50% by mass of coal.

[0052] Preferably, the mixing stage is carried out using 5 to 10% by mass of the binder.

[0053] Optionally, the mixing step additionally involves mixing 5 to 15% by mass of an iron-based compound (such as iron oxide or metallic iron) to form an iron-containing agglomerate.

[0054] It should be noted that due to the temperature below 800 °C, the solid agglomerate and the method for preparing it have considerable energy savings during the manufacturing process.

[0055] The coked solid agglomerate can be used in blast furnaces and sintering furnaces. The iron-containing solid agglomerate can be used to replace small coke in blast furnaces.

[0056] Solid Carbonized Mass with Calcium Source

[0057] Figure 1 The flowchart of the manufacturing method for solid carbonized agglomerates is illustrated. Preferably, the manufacturing method includes mixing at least one carbon source 10, at least one calcium source 11, and at least one binder 12, mechanically forming 200 the mixture using a rotating roller to form a briquetted agglomerate 20, and pyrolyzing 400 the formed agglomerate 20 at a temperature between 600 °C and 800 °C such that the material is carbonized.

[0058] Optionally, after the mechanical forming step 200, the method of the present invention includes drying the formed agglomerate 20 in an oven at 105 °C for two hours, wherein the humidity inside the oven is less than 1%.

[0059] Preferably, the step of pyrolyzing 400 the formed agglomerate 20 is carried out in a cylindrical rotating reactor. This heat treatment carbonizes the carbonaceous materials in the mixture and increases the interaction and anchoring between all components of the solid agglomerate, thereby improving its mechanical strength. In addition, the pyrolysis of the solid agglomerate promotes its drying and pre-reduction, thereby increasing its calorific value and preparing it for use in a blast furnace.

[0060] Preferably, at least one carbon source 10 is at least one of the following: biochar, coal, and / or metallurgical coal. For the purposes of this specification, biochar means any charcoal of plant origin produced according to substantially sustainable criteria. Preferably, such biochar has a low inorganic content (less than 1%).

[0061] Preferably, at least one calcium source 11 is a calcium oxide source from at least one of the following: the main source of calcium (limestone) or calcium-containing steel waste.

[0062] Preferably, at least one binder 12 is an organic binder such as starch.

[0063] Preferably, the mixing step 100 is carried out using 60 to 90% by mass of the carbon source 10. More preferably, the mixing step 100 is carried out using 60 to 80% by mass of the carbon source 10. Preferably, the carbon source 10 is formed by at most 70% by mass of biochar and 30 to 100% by mass of coal.

[0064] Preferably, the mixing step 100 is carried out using 0 to 10% by mass of at least one binder 12. More preferably, the mixing step 100 is carried out using 5 to 10% by mass of at least one binder 12.

[0065] Preferably, mixing step 100 includes mixing 10 to 40% by mass of at least one calcium source 12. More preferably, mixing step 100 includes mixing 25 to 35% by mass of at least one calcium source 12. Even more preferably, mixing step 100 includes mixing 27 to 32% by mass of at least one calcium source 12.

[0066] The present invention additionally provides a carbonized solid lump for a blast furnace, the composition of which comprises: at least one carbon source 10; at least one calcium source 11; and at least one binder 12; wherein, after the mechanical forming 200 of the solid lump, the solid lump undergoes a pyrolysis step 400 at a temperature greater than or equal to 600 °C and less than 800 °C; wherein the solid lump contains 25 to 35% by mass of at least one calcium source 11.

[0067] Once having undergone mechanical forming, the formed lump 20 undergoes a pyrolysis stage 400 at a temperature preferably between 600 °C and 800 °C. More preferably, the pyrolysis step 400 is carried out at a temperature greater than or equal to 600 °C and less than 700 °C. Optionally, the pyrolysis step 400 is carried out at a temperature greater than or equal to 700 °C and less than 800 °C.

[0068] Optionally, before pyrolyzing the lump 400, the formed lump 20 is dried in an oven at 105 °C for two hours, wherein the humidity in the oven is less than 1%.

[0069] Preferably, at least one carbon source 10 is at least one of the following: biochar, coal, and / or metallurgical coal.

[0070] Preferably, at least one calcium source 11 is a calcium oxide source from at least one of the following: calcitic limestone, dolomitic limestone, slaked lime, and / or quicklime.

[0071] Preferably, at least one binder 12 is an organic binder such as starch.

[0072] Preferably, the solid lump of the present invention contains 60 to 90% by mass of calcium source, wherein the carbon source 10 includes at most 70% by mass of biochar and 30 to 100% by mass of coal. More preferably, the solid lump contains 60 to 80% by mass of calcium source, wherein the carbon source 10 includes at most 70% by mass of biochar and 30 to 100% by mass of coal.

[0073] Preferably, the solid agglomerate of the present invention contains 0 to 10% by mass of at least one binder 12. More preferably, the solid agglomerate of the present invention contains 5 to 10% by mass of at least one binder 12. The binder 12 has the function of keeping the compounds in the solid agglomerate bound together. The use of the binder 12 also allows the use of compounds with smaller particle sizes in the composition of the solid agglomerate.

[0074] Preferably, the solid agglomerate of the present invention contains 10 to 40% by mass of at least one calcium source 12. More preferably, the solid agglomerate contains 25 to 35% by mass of at least one calcium source. More preferably, the mixing step 100 includes mixing 27 to 32% by mass of at least one calcium source 12.

[0075] The calcium source 12 used is preferably steel waste, such as sludge from the steelmaking process. Due to the catalytic action of the calcium component of the calcium-containing agglomerate, the reaction of the carbonaceous material starts at a lower temperature (compared to conventional coke), and as a result, a reduction effect can be expected. And as a result, when using the calcium-containing agglomerate as the burden in a steelmaking furnace, a reduction effect on the reductant ratio (RAR) can be expected by reducing the temperature in the regenerative heating zone.

[0076] Preferably, the solid agglomerate of the present invention is a catalytic briquette for a blast furnace.

[0077] Therefore, the solid carbonized agglomerate according to the present invention and the method for manufacturing the solid carbonized agglomerate are attractive because they allow the blast furnace to improve its efficiency in reducing iron oxides, thereby optimizing fuel consumption and thus reducing CO2 emissions.

[0078] In addition, using a calcium oxide source instead of an iron oxide source in the agglomerate provides the following advantages: (1) obtaining a more durable agglomerate because a part of the physical degradation of the briquette with iron oxide is the consumption of the structural carbon used for reduction at high temperatures during the carbonization process, (2) calcium oxide is more effective in terms of catalytic ability compared to iron (metal or wüstite), (3) in the steel industry, a large amount of calcium-containing waste is generated, which allows this material to be used in large quantities in the agglomerates of the present invention, thus allowing the reuse of these wastes and reducing the environmental impact of disposing of them, (4) the calcium oxide-containing briquette can be carbonized in a conventional coke oven because iron oxide reacts with the silicon oxide present in the refractory of the coke oven and forms a low-melting phase that corrodes the refractory, (5) they are more interestingly used in a low-temperature carbonization process because the oxide source (CaO) is already a catalytic phase where no pre-reduction is required.

[0079] It should also be noted that calcium oxide (CaO) is the catalyst in the Boudouard reaction (gasification reaction), while in the case of iron oxides, the catalyst is metallic iron (mainly). In other words, in order for the clusters containing iron to have catalytic activity, high temperatures must be reached and reduction must be induced. In the case of calcium production at low temperatures, the catalytic phase already exists.

[0080] It should also be noted that the present invention does not exclude the use of mixed materials to form solid agglomerates, such as waste materials rich in CaO and iron oxides in their composition. This form of the present invention (using solid carbonized agglomerates containing at least one calcium source 12 and at least one iron source) is advantageous because it reuses steel mill waste containing these materials, which might previously have been discarded and caused environmental damage. In addition, such agglomerates combine the catalytic actions of iron and calcium, thus making them self-heating.

[0081] Optionally, the solid carbonized agglomerates of the present invention additionally contain 5 to 15% by mass of iron-based compounds, such as iron oxides or metallic iron.

[0082] Optionally, the mixing step 100 of the method for manufacturing solid carbonized agglomerates includes mixing 5 to 15% by mass of iron-based compounds, such as iron oxides or metallic iron.

[0083] Previously, it has been seen that the solid agglomerates of BR102022023262-8 can be pyrolyzed at temperatures below 800 °C (specifically between 700 °C and 800 °C). However, with the introduction of the calcium source 11 into the agglomerates, it has been found that, in addition to the previous range of 700 °C to 800 °C, the pyrolysis step can be carried out at even lower temperatures (specifically between 600 °C and 700 °C), which requires less energy to manufacture and provides the advantages highlighted above, with better catalytic performance than the agglomerates of BR102022023262-8.

[0084] Allows a large number of variations that affect the scope of protection of this request. This reinforces the fact that the present invention is not limited to the specific configurations / embodiments described above.

Claims

1. A solid carbonized agglomerate for a blast furnace, characterized in that: Its composition includes: at least one carbon source (10); at least one calcium source (11); and at least one binder (12); wherein, after the mechanical forming (200) of the solid mass, the solid mass is subjected to a pyrolysis step (400) at a temperature greater than or equal to 600° C. and less than 800° C.; The solid mass contains 25 to 35% by mass of at least one calcium source (11).

2. The solid mass according to claim 1, characterized in that The at least one carbon source (10) is at least one of the following: biochar, coal and / or metallurgical coal.

3. The solid mass according to claim 1 or 2, characterized in that: The at least one calcium source (11) is a calcium oxide source from at least one of the following: limestone or calcium-containing steel waste.

4. The solid mass according to any one of claims 1 to 3, characterized in that At least one binder (12) is an organic binder.

5. The solid mass according to any one of claims 1 to 4, characterized in that The solid mass contains 60 to 90% by mass of a carbon source (10).

6. The solid mass according to claim 5, characterized in that The carbon source (10) comprises up to 70% by mass of biochar and between 30 and 100% by mass of coal.

7. The solid mass according to any one of claims 1 to 6, characterized in that The solid mass contains 5 to 10% by mass of at least one binder (12).

8. The solid mass according to any one of claims 1 to 7, characterized in that The solid mass contains 5 to 15 mass % of an iron-based compound, such as iron oxide or metallic iron.

9. A method for producing solid carbonized briquettes for blast furnaces, characterized in that: The method comprises the following stages: mixing (100) at least one carbon source (10), at least one calcium source (11), and at least one binder (12); Mechanically shaping (200) the mixture of the at least one carbon source (10), the at least one calcium source (11) and the at least one binder (12) to form a solid shaped mass (20); as well as Pyrolyzing the shaped solid mass (20) at a temperature greater than or equal to 600° C. and less than 800° C. (400); The solid mass contains 25 to 35% by mass of at least one calcium source (11).

10. The method according to claim 9, characterized in that The at least one carbon source (10) is at least one of: biochar, coal and / or metallurgical coal; and the mixing (100) comprises: 60 to 90 mass % of the carbon source (10) is mixed.

11. The method according to claim 10, characterized in that The method comprises utilizing up to 70 mass % biochar and between 30 and 100 mass % coal to form the carbon source (10).

12. The method according to any one of claims 9 to 11, characterized in that The mixing (100) includes mixing 5 to 10 mass % of the at least one binder.

13. The method according to any one of claims 9 to 12, characterized in that The mixing (100) includes mixing 5 to 15 mass % of an iron-based compound, such as iron oxide or metallic iron.

14. The method according to any one of claims 9 to 13, characterized in that The method further comprises, after the mechanical forming step (200), drying (300) the formed mass (20) in an oven at 105°C for two hours, wherein the humidity in the oven is less than 1%.

Images