Method for manufacturing calcined magnesia chrome refractories using renewable byproducts

Abstract

The present invention relates to a method for manufacturing calcined magnesia-chromium refractories using recycled raw material by-products, and more specifically, to a method for manufacturing calcined magnesia-chromium refractories using by-products containing magnesium oxide generated during the regeneration process of discarded carbon-containing fluororefractories.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing calcined magnesia-chromium refractories using recycled raw material by-products, and more specifically, to a method for manufacturing calcined magnesia-chromium refractories using by-products containing magnesium oxide generated during the regeneration process of discarded carbon-containing magnesia refractories. Background Technology

[0002] Carbon-containing magnesia refractories, represented by MgO-C, are consumed by melting into molten steel and slag used in the furnace; as a result, about 33% is consumed, and the remainder is dismantled, generating waste refractories. Conventionally, only a portion of this was used as a slag aid, and most of it was landfilled, but currently, it is being utilized as recycled raw material after undergoing a refining process.

[0003] Typically, 50% by weight of recovered waste MgO-C refractories is lost during the process of removing the altered layer and decarburizing, and after undergoing a purification process, recycled magnesia raw materials and by-products are produced in a ratio of approximately 1:1 by weight. Of these, recycled magnesia raw materials with an MgO purity of over 96% are entirely used as raw materials for refractories, but the surplus volume of by-products generated during the purification process is increasing. While these by-products are partially used for amorphous refractories, there is a need to increase their usage to improve the utilization rate of recycled waste refractories.

[0004] Therefore, if calcined refractories of equivalent quality to current products are provided even when the magnesia raw material used in the manufacturing process of calcined refractories is replaced with a byproduct of refractory recycling, it would be useful for securing the economic viability of the entire process based on the active utilization of the byproduct and for environmental protection by reducing the amount of byproduct landfilled; however, a method for manufacturing calcined refractories using such recycled raw material byproducts is not yet available. Prior art literature

[0005] Republic of Korea Published Patent Application No. 10-2011-0124661 ("Method for Regenerating Waste Mag-Carbon Refractory Material", published Nov. 17, 2011) The problem to be solved

[0006] The problem that the present invention aims to solve is to provide a method for manufacturing calcined magnesia-chromium refractories using refractory regeneration by-products generated during the process of converting discarded carbon-containing fluororefractories into recycled raw materials after decarburization.

[0007] Another problem that the present invention aims to solve is to ensure the economic viability of the entire process and prevent environmental pollution by increasing the reuse efficiency of waste refractories through the utilization of refractory regeneration by-products generated during the process of converting discarded carbon-containing fluororefractories into recycled raw materials following decarburization.

[0008] The problems that the present invention aims to solve are not limited to those mentioned above, and any unmentioned problems that the present invention aims to solve will be clearly understood by a person skilled in the art to which the present invention pertains from the description below. means of solving the problem

[0009] According to one embodiment of the present invention, a method for manufacturing a calcined magnesia-chromium refractory is provided, comprising the steps of: crushing and decarburizing discarded carbon-containing fluororefractory to produce refractory-regenerating magnesia and refractory-regenerating by-products; and mixing a magnesia raw material, a chromium ore raw material, and the refractory-regenerating by-products and calcining at a high temperature to produce a calcined magnesia-chromium refractory, wherein the content of MgO contained in the refractory-regenerating magnesia is 96% by weight or more and less than 100% by weight, the content of MgO contained in the refractory-regenerating by-products is 85% by weight or more and less than 96% by weight, and the refractory-regenerating by-products are included in an amount of 5 to 20% by weight based on 100% by weight of the calcined magnesia-chromium refractory.

[0010] For example, the content of MgO in the above refractory regeneration byproduct may be 86.8 to 94.0 weight%.

[0011] For example, the content of Al2O3 in the above refractory regeneration byproduct may be 0.1 to 9.5 weight%.

[0012] For example, the content of SiO2 in the above refractory regeneration byproduct may be 0.1 to 4.0 weight%.

[0013] For example, the refractory regeneration byproduct may comprise a first particle having a particle size distribution of 0.3 to 1.0 mm and a second particle having a particle size distribution of 0.001 to 0.075 mm, wherein the content of the first particle in the refractory regeneration byproduct may be 45 to 70 weight% and the content of the second particle may be 0.1 to 10 weight%.

[0014] For example, the content of MgO in the above-mentioned calcined magnesia-chromium refractory may be 50 to 85 weight%, and the content of Cr2O3 may be 10 to 30 weight%.

[0015] For example, the calcined magnesia-chromium refractory may comprise one or more flux components selected from the group comprising Al2O3, Fe2O3, SiO2, and CaO.

[0016] For example, the content of the flux component in the above-mentioned calcined magnesia-chromium refractory may be greater than 0 and greater than 20% by weight.

[0017] For example, the step of manufacturing the calcined magnesia-chromium refractory may be a step of additionally mixing Cr2O3 powder with the magnesia raw material and the chromium ore raw material.

[0018] For example, the above Cr2O3 powder may be included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total calcined magnesia-chromium refractory.

[0019] For example, the above Cr2O3 powder may have a particle size distribution of 0.01 to 0.075 mm.

[0020] For example, the step of manufacturing the above-mentioned calcined magnesia-chromium refractory may be performed at a calcination temperature of 1,600 to 1,800°C. Effects of the invention

[0021] According to the present invention, a method for manufacturing a calcined magnesia-chromium refractory using a refractory regeneration byproduct generated during the process of converting discarded carbon-containing fluorinated refractory into a regenerated raw material after decarburization can be provided.

[0022] In addition, according to the present invention, by utilizing the refractory regeneration by-product generated during the process of converting discarded carbon-containing fluorinated refractories into recycled raw materials after decarburization, the reuse efficiency of waste refractories can be increased, thereby ensuring the economic feasibility of the entire process and preventing environmental pollution.

[0023] The excellent and / or useful effects according to the present invention are not limited to the effects of the present invention described above, and a person skilled in the art will also be able to obviously recognize, based on the invention of this specification, excellent and / or useful effects of the present invention not explicitly disclosed in this specification, which are intentionally disclosed by this specification and should be understood to be obviously included within the scope of the present invention. Brief explanation of the drawing

[0024] FIG. 1 is a flowchart briefly illustrating a method for manufacturing a calcined magnesia-chromium refractory according to one embodiment of the present invention. Specific details for implementing the invention

[0025] The following detailed description of the invention refers to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that various embodiments of the invention are different but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in relation to one embodiment. It should also be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the following detailed description is not intended to be limiting, and the scope of the invention is limited only by the appended claims, including all equivalents to those claimed therein, provided appropriately described. Similar reference numerals in the drawings refer to the same or similar functions across various aspects.

[0026] Furthermore, the terms or words used in this specification and claims are not intended to be interpreted as being limited to their commonly accepted dictionary meanings, and a person skilled in the art will clearly understand that said terms or words are used within the scope of conveying the meaning of the present invention, within the scope of expressing the concept that this specification and claims obviously intend to convey.

[0027] Furthermore, a person skilled in the art will clearly understand that the configurations described in the aspects, embodiments, examples, etc. of the present invention in this specification are merely preferred examples presented at the time to enable a person skilled in the art to understand and reproduce the present invention, and are not intended to limit the present invention thereto.

[0028] Furthermore, the descriptions and specific embodiments regarding each configuration described in this specification may be obviously applied to the descriptions and specific embodiments of each other configuration. That is, a person skilled in the art will clearly understand that all possible combinations of the various configurations and specific embodiments disclosed in this specification fall within the scope disclosed herein.

[0029] As used herein, the term "and / or" is a term comprising each of the items mentioned and all combinations of two or more. Additionally, where a singular term is used herein, it is disclosed including the plural form unless otherwise noted.

[0030] As used herein, the terms "comprise" and "comprising" are terms that permit the existence or addition of items other than those mentioned, and as used herein, the terms "consist," "consist," "consisting," and "consisting" are terms that do not permit the existence or addition of items other than those mentioned.

[0031] As used in this specification, the term "to" indicates a numerical range in which the range of values ​​represented by "to" includes the values ​​listed before and after the term as lower and upper values, respectively. Where multiple upper and / or lower values ​​of an arbitrary numerical range are disclosed, the numerical range is disclosed such that any one of the multiple lower values ​​and any one of the multiple upper values ​​are respectively set as the lower and upper values.

[0032] The terms “about” and / or “approximately” as used in this specification refer to a numerical range between a 10% upper limit value and a lower limit value based on the value indicated using “about” and / or “approximately”.

[0033] Terms or words used in this specification and claims should not be interpreted as being limited to their ordinary dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the configurations described in the embodiments described in this specification are merely preferred embodiments of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0034] Meanwhile, each description and embodiment disclosed in this specification may also be applied to other descriptions and embodiments. That is, all combinations of the various elements disclosed in this specification fall within the scope of the invention, and descriptions omitted in one embodiment may be interpreted in the same manner as described in other embodiments. Furthermore, the scope of the invention should not be considered limited by the specific descriptions provided below.

[0036] According to one embodiment of the present invention, a method for manufacturing a calcined magnesia-chromium refractory is provided, comprising the steps of: crushing and decarburizing discarded carbon-containing fluororefractory to produce refractory-regenerating magnesia and refractory-regenerating by-products; and mixing a magnesia raw material, a chromium ore raw material, and the refractory-regenerating by-products and calcining at a high temperature to produce a calcined magnesia-chromium refractory, wherein the content of MgO contained in the refractory-regenerating magnesia is 96% by weight or more and less than 100% by weight, the content of MgO contained in the refractory-regenerating by-products is 85% by weight or more and less than 96% by weight, and the refractory-regenerating by-products are included in an amount of 5 to 20% by weight based on 100% by weight of the calcined magnesia-chromium refractory.

[0037] Calcined magnesia-chromium refractory is a material having MgO (magnesia) and Cr2O3 (chromium oxide) as its main components, and these two components can improve the durability of the refractory by forming a stable bond at high temperatures. In particular, high-quality calcined magnesia-chromium refractory can be manufactured by mixing magnesia clinker raw material components and chromium ore clinker raw material components and calcining them at high temperatures to induce thermochemical changes in advance and alter the bonding structure, so that the actual refractory can be used stably without deformation when used in a high-temperature environment. During this process, the composition and properties of each mixed component change, and loss on ignition (lg-loss) may occur; for example, the above-mentioned refractory regeneration byproduct may have a loss on ignition value of 0.01 to 0.6 before calcination.

[0038] For the manufacture of calcined magnesia-chromium refractories, only magnesia clinker raw materials having an MgO content of 96% or more are typically used. However, the present invention focuses on the fact that even when refractory regeneration by-products are mixed with such conventional magnesia clinker raw materials and used as magnesia clinker raw materials, calcined magnesia-chromium refractories of excellent quality can be obtained. For example, the magnesia that serves as the conventional magnesia clinker raw material may include seawater magnesia, sintered magnesia, fused magnesia, etc.

[0039] For the manufacture of calcined magnesia-chromium refractories, natural chromium ore, fused magnesia-chromium, etc., may be used as raw materials containing chromium oxide components. In addition, to ensure the amount of chromium oxide required to achieve the quality of the finally obtained calcined magnesia-chromium refractories, additional chromium oxide powder may be introduced separately from the chromium ore clinker.

[0040] When 5 to 20 parts by weight of refractory recycling by-products are included based on 100 parts by weight of the total calcined magnesia-chromium refractory raw material containing magnesia clinker components (calcined magnesia-chromium refractory raw material comprising a magnesia clinker raw material consisting of a conventional magnesia clinker raw material and a refractory recycling by-product, and a chromium ore clinker raw material), economic feasibility in the manufacturing process of the calcined refractory is ensured, and substantially equivalent physical properties can be achieved even when compared to the case where the magnesia clinker raw material consists only of high-grade magnesia such as seawater magnesia.

[0041] For example, the MgO content in the above refractory regeneration byproduct may be 5% or more and less than 96% by weight, which is lower than the standard MgO content of 96% or more that can be used as refractory regeneration magnesia, more preferably 86.8 to 94.0% by weight, the Al2O3 content may be 0.1 to 9.5% by weight, and the SiO2 content may be 0.1 to 4.0% by weight.

[0042] For example, the above refractory regeneration byproduct may have a particle size of 1.0 mm or less, more specifically, may include a first particle having a particle size distribution of 0.3 to 1.0 mm and a second particle having a particle size distribution of 0.001 to 0.075 mm, and the content of the first particle in the refractory regeneration byproduct may be 45 to 70 weight% and the content of the second particle may be 0.1 to 10 weight%.

[0043] In addition, when mixing magnesia clinker and chrome ore clinker as described above, the compounds included in the mixture contain Al2O3, Fe2O3, SiO2, CaO, etc., in addition to the main components MgO and Cr2O3.

[0044] The main components, MgO and Cr2O3, react to form secondary spinel (MgCr2O4) with the highest melting point, and the remaining components, Al2O3, Fe2O3, SiO2, and CaO, play a role in lowering the melting point when dissolved in MgCr2O4.

[0045] For example, the content of MgO in the above-mentioned calcined magnesia-chromium refractory may be 50 to 85 weight%, and the content of Cr2O3 may be 10 to 30 weight%.

[0046] If the MgO content is less than 50 wt% or the Cr2O3 content is more than 30 wt%, the composition of the secondary spinel changes from MgCr2O4 to Mg(Cr,Al)2O4, (Mg,Fe)(Cr,Al)2O4, etc. due to high-temperature volatilization of Cr2O3 and diffusion of flux components under low oxygen partial pressure, and thus the melting point is lowered, the refractory resistance may be reduced. Also, if the MgO content is more than 85 wt% or the Cr2O3 content is less than 10 wt%, the refractory resistance to CaO-MnO-SiO2 slag with a basicity ratio close to 1 and high MnO content may be reduced. Therefore, it is desirable that the MgO content and the Cr2O3 content satisfy the above numerical ranges.

[0047] For example, the above-mentioned refractory material may contain one or more flux components selected from the group comprising Al2O3, Fe2O3, SiO2, and CaO.

[0048] For example, the content of the flux component in the above refractory material may be greater than 0 and greater than 20% by weight. If the content of the flux component is greater than 20% by weight, the melting point of the secondary spinel produced is lower and the amount of silicate-based liquid phase increases, which may reduce the durability of the refractory material; therefore, it is desirable for the content of the flux to satisfy the above numerical range.

[0049] The above secondary spinels are produced by high-temperature firing and can play a role in enhancing the refractory's resistance by strongly bonding the magnesia clinker and chrome ore clinker and discontinuously distributing the silicate-based liquid phase (CaO-SiO2-MgO) generated from the flux components.

[0050] For example, the step of manufacturing the above-mentioned calcined refractory may be a step of additionally mixing Cr2O3 powder into the magnesia clinker component and the chrome ore clinker component. The Cr2O3 powder can improve the durability of the refractory by reacting with the magnesia clinker to promote the formation of a secondary spinel of MgCr2O4 composition.

[0051] For example, the above Cr2O3 powder may be included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total fired refractory material, and may have a particle size distribution of 0.01 to 0.075 mm.

[0052] If the content of the above Cr2O3 powder is less than 1 weight% or the particle size is greater than 0.075 mm, spinel formation is low, so the improvement in the refractory's durability is low. If the content is greater than 3 weight% or the particle size is less than 0.01 mm, the improvement in durability due to spinel formation is similar, but the amount of residual expansion increases significantly, causing the structure to loosen and the air permeability to increase, which may result in a decrease in durability. Therefore, it is desirable that the content and particle size distribution of the above Cr2O3 powder each satisfy the above numerical ranges.

[0053] For example, the step of manufacturing the above-mentioned refractory material may be performed at a firing temperature of 1,600 to 1,800°C. If the firing temperature is lower than 1,600°C, the formation of secondary spinels is reduced, which lowers the durability of the refractory material, and if it is higher than 1,800°C, the formation of secondary spinels is similar but energy costs increase, so it is desirable for the firing temperature to satisfy the above numerical range.

[0054] The present invention will be explained in more detail below using examples. Process conditions and preparation steps not specified in the following examples may be obvious in the art to which the present invention belongs, and a person skilled in the art will be able to select them without particular difficulty based on the present invention and reproduce the problem-solving principle of the present invention.

[0055] In addition, regarding the manufacturing method according to the present invention, unless otherwise specified, each step constituting the manufacturing method is carried out at room temperature (25°C), and each step should be understood to be performed by means and tools that a person skilled in the art can derive without particular difficulty.

[0057] Example 1: Preparation of calcined magnesia-chromium refractory according to the present invention

[0058] The altered layer of carbon-containing fluorocarbon refractory waste from the silo was removed, and the mixture was crushed and decarburized to produce refractory regenerated magnesia and refractory regenerated by-products in a ratio of approximately 1:1. Based on weight, a magnesia clinker component was prepared using the seawater magnesia:refractory regenerated by-product ratio in the amounts listed in Table 1 below, and a chromium ore clinker with a Cr2O3 content of 10 to 40 wt% was mixed in the amount listed in Table 1 below. Subsequently, Cr2O3 powder was added in the amount listed in Table 1 below to adjust the chromium content in the total mixture.

[0059] The content of MgO contained in the above refractory regeneration byproduct was 86.8 to 94.0 wt%, the content of Al2O3 was 0.1 to 9.5 wt%, and the content of SiO2 was 0.1 to 4.0 wt%, and the loss on ignition was confirmed to be about 0.01 to 0.6, and particles having a particle size distribution of 0.3 to 1.0 mm were 45 to 70%, and particles having a particle size distribution of less than 0.075 mm were 10% or less.

[0060] The mixture was formed using a uniaxial forming machine, and the resulting molded product was loaded into a gas kiln and fired at a temperature of 1,600 to 1,800°C, with the firing time maintained at 5 hours. Test specimens were prepared by processing the fired refractory material manufactured as described above.

[0062] Examples 2 to 6: Preparation of calcined magnesia-chromium refractories according to the present invention

[0063] The calcined magnesia-chromium refractories of Examples 2 to 6 were prepared in the same manner as described in Example 1 above, except that each component was used in the amounts indicated in Tables 1 and 2 below, and test specimens were prepared.

[0065] Comparative Examples 1 to 4: Preparation of calcined magnesia-chromium refractories as comparison subjects

[0066] The calcined magnesia-chromium refractories of Comparative Examples 1 to 4 were prepared in the same manner as described in Example 1 above, except that each component was used in the amounts indicated in Tables 1 and 2 below, and test specimens were prepared.

[0068] division Comparative Example 1 Example 1 Example 2 Comparative Example 2 Example 3 Example 4 Mixture (weight%) MgO 44 39 34 66 56 46 by-product - 5 10 - 10 20 Chrome shine 52 52 52 30 30 30 chromium oxide 1.0 1.0 1.0 1.0 1.0 1.0 bookbinder 3.0 3.0 3.0 3.0 3.0 3.0

[0070] division Comparative Example 3 Example 5 Example 6 Comparative Example 4 Mixture (weight%) MgO 48 38 28 18 by-product - 10 20 30 Chrome shine 49 49 49 49 chromium oxide - - - - bookbinder 3.0 3.0 3.0 3.0

[0072] Experimental Example: Evaluation of Physical Properties and Performance of Calcined Magnesia-Chromium Refractories

[0073] For the performance evaluation regarding porosity and bulk specific gravity, samples corresponding to each comparative example and example were processed to a size of 60×60×30 mm, immersed in water or white kerosene, and then subjected to a vacuum of ±150 mmHg. The specific gravity and porosity of the specimens were measured by the Archimedes method, and the density and volume of open pores of the product were measured. Additionally, for the performance evaluation regarding compressive strength, samples corresponding to each comparative example and example were processed to a size of 60×60×60 mm and subjected to pressure in a compression testing machine to measure the compressive strength in kg / cm² units, and to verify the bonding strength and firing temperature (degree of sintering) of the specimens. Furthermore, for the performance evaluation regarding hot flexural strength, the Hot Modulus of Rupture (Hot MOR) of the samples corresponding to each comparative example and example was measured at a maximum of 1,600°C to verify the bonding state of the microstructure and grain sinterability at hot conditions. In addition, for the performance evaluation of the erosion test, cylindrical structures were constructed using six or eight specimens corresponding to each comparative example and example, and the erosion test was conducted by heating them to the actual operating temperature and then adding molten steel and CaO-SiO2-based slag. After the test was completed, the molten steel and residual erosion agent were removed, the cooled specimens were cut, and the ratio of the eroded surface was measured to calculate the damage index. The damage index was converted into a percentage based on Comparative Example 1 and is indicated in Tables 3 and 4 below.

[0075] division Comparative Example 1 Example 1 Example 2 Comparative Example 2 Example 3 Example 4 Physical properties Porosity (%) 17.4 17.6 17.8 16.8 16.2 16.5 Bulk specific gravity (g / cm³) 3 ) 3.16 3.15 3.14 3.06 3.08 3.07 Compressive strength (kg / cm²) 2 ) 581 619 721 583 540 662 Hot flexural strength (kg / cm²) 2 ) 23 55 35 27 33 25 Corrosion resistance Jisu (Mangso) 100 102 107 100 93 108 Thermal Shock Test Quality Level (○ Good, △ Cracked, X Detachment) ○ ○ ○ ○ ○ ○ Availability - fitness fitness - fitness fitness

[0077] division Comparative Example 3 Example 5 Example 6 Comparative Example 4 Physical properties Porosity (%) 15.8 16.4 16.7 17.1 Bulk specific gravity (g / cm³) 3 ) 3.20 3.19 3.21 3.23 Compressive strength (kg / cm²) 2 ) 990 1001 889 776 Hot flexural strength (kg / cm²) 2 ) 85 91 95 83 Corrosion resistance Jisu (Mangso) 100 104 108 116 Thermal Shock Test Quality Level (○ Good, △ Cracked, X Detachment) ○ ○ △ X Availability - fitness fitness Non-conforming

[0079] Referring to Tables 3 and 4 above, it was confirmed that the calcined magnesia-chromium refractory according to the present invention is sufficiently usable as a calcined refractory and has excellent overall physical properties and performance, as it exhibits similar physical properties, corrosion resistance, and thermal shock test results to a calcined magnesia-chromium refractory that does not contain the refractory regeneration by-product and whose magnesia clinker is composed only of high-grade magnesia such as seawater magnesia, even when containing a certain proportion of the refractory regeneration by-product.

[0081] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also included within the scope of the present invention.

Claims

Claim 1 A method for manufacturing magnesia-chromium calcined refractories, comprising the step of crushing and decarburizing discarded carbon-containing fluororefractories to produce refractory-regenerating magnesia and refractory-regenerating by-products; The method comprises the step of mixing a magnesia raw material, a chrome ore raw material, and the refractory regeneration by-product, and calcining at a high temperature to produce a calcined magnesia-chrome refractory, wherein the content of MgO contained in the refractory regeneration magnesia is 96% by weight or more and less than 100% by weight, the content of MgO contained in the refractory regeneration by-product is 85% by weight or more and less than 96% by weight, and the refractory regeneration by-product is included in an amount of 5 to 20 parts by weight based on 100 parts by weight of the calcined magnesia-chrome refractory, comprising a first particle having a particle size distribution of 0.3 to 1.0 mm and a second particle having a particle size distribution of 0.001 to 0.075 mm, and wherein the content of MgO in the calcined magnesia-chrome refractory is 50 to 85% by weight and the content of Cr2O3 is 10 to 30% by weight. Method for manufacturing magnesia-chromium refractory. Claim 2 A method for manufacturing a calcined magnesia-chromium refractory according to claim 1, wherein the content of MgO in the refractory regeneration byproduct is 86.8 to 94.0 wt%, the content of Al2O3 is 0.1 to 9.5 wt%, and the content of SiO2 is 0.1 to 4.0 wt%. Claim 3 A method for manufacturing a calcined magnesia-chromium refractory according to claim 2, wherein the content of the first particle in the refractory regeneration byproduct is 45 to 70 weight% and the content of the second particle is 0.1 to 10 weight%. Claim 4 delete Claim 5 A method for manufacturing a calcined magnesia-chromium refractory according to claim 1, wherein the calcined magnesia-chromium refractory comprises one or more flux components selected from the group comprising Al2O3, Fe2O3, SiO2, and CaO. Claim 6 A method for manufacturing a calcined magnesia-chromium refractory according to claim 5, wherein the content of the flux component in the calcined magnesia-chromium refractory is greater than 0 and greater than 20% by weight. Claim 7 A method for manufacturing a calcined magnesia-chromium refractory according to claim 1, wherein the step of manufacturing the calcined magnesia-chromium refractory is to additionally mix Cr2O3 powder with the magnesia raw material and the chromium ore raw material. Claim 8 A method for manufacturing a calcined magnesia-chromium refractory according to claim 7, wherein the Cr2O3 powder is included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total calcined magnesia-chromium refractory. Claim 9 A method for manufacturing a calcined magnesia-chromium refractory according to claim 8, wherein the Cr2O3 powder has a particle size distribution of 0.01 to 0.075 mm. Claim 10 A method for manufacturing a calcined magnesia-chromium refractory, wherein, in any one of claims 1 to 3 and 5 to 9, the step of manufacturing the calcined magnesia-chromium refractory is performed at a calcination temperature of 1,600 to 1,800°C.

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