Process for smelting silicon-chromium alloy by adopting oxygen-enriched top-bottom double-blowing method

Abstract

The invention provides a process for smelting silicon-chromium alloy by adopting an oxygen-enriched top-bottom double-blowing method, and belongs to the technical field of alloy smelting, and the process comprises the following steps: S1, pretreatment: weighing silica, coke and high-carbon ferro-chrome in parts by weight, respectively performing crushing treatment, and uniformly mixing the production raw materials; s2, smelting: feeding the uniformly mixed production raw materials into an electric furnace, and electrifying for smelting to form molten steel; the molten steel in the furnace is poured into a steel ladle, a carbon removal agent is blown to the surface of the molten steel from the upper portion of the steel ladle, and meanwhile oxygen-containing gas is blown into the molten steel from the bottom of the steel ladle; and S4, casting: after the oxygen-containing injection is finished, carrying out slag stopping and tapping on the molten steel, pouring into a fixed mold, and cooling and solidifying to form a casting blank, namely the silicon-chromium alloy. According to the method, the carbon content is remarkably reduced, the control precision of the carbon content is improved, the silicon content in the silicon-chromium alloy is greatly improved through the carbon removal agent, it is ensured that the high-grade silicon-chromium alloy is stably produced, a new way is developed for utilization of the fly ash, and the production cost of the silicon-chromium alloy is reduced.

Description

Technical Field

[0001] This invention relates to the field of alloy smelting technology, and in particular to a process for smelting silicon-chromium alloys using an oxygen-enriched top-bottom double-blowing method. Background Technology

[0002] Silicon-chromium alloy is a ferroalloy made by mixing silicon (Si) and chromium (Cr) in a certain proportion. It contains a high proportion of chromium and silicon, and usually also contains small amounts of carbon (C) and other elements. This alloy appears as a silvery-gray block or powder and has the characteristics of high temperature resistance and oxidation resistance. In industrial production, the silicon content is generally between 30-45%, which can be used to improve the high-temperature strength and oxidation resistance of steel, as well as reduce the coefficient of thermal expansion and improve the thermal shock resistance of steel. The chromium content is about 30-40%, which can be used to improve the hardness, wear resistance and corrosion resistance of steel, as well as improve the high-temperature performance of steel, enabling it to withstand higher temperatures. Different ratios of silicon and chromium will significantly affect the performance of the alloy. Silicon-chromium alloys can be used as deoxidizers in steelmaking, effectively removing oxygen molecules from molten steel. They can also be used to increase carbon content and adjust steel composition. They are also key additives in the production of stainless steel, enhancing its corrosion resistance, heat resistance, and hardness. Furthermore, they can be used as casting modifiers to improve the fluidity of molten iron, reduce porosity defects in castings, and introduce stable silicon and chromium elements into steel, thereby improving its mechanical properties, wear resistance, and oxidation resistance. Compared to pure chromium metal, alloys are more economical and can reduce production costs.

[0003] Existing methods for producing silicon-chromium alloys are relatively mature; however, the combined silicon and chromium content in these alloys is typically only slightly above 70%. While this meets industry and standard requirements, the overall production quality remains poor, leaving room for improvement. Therefore, smelting and producing a silicon-chromium alloy with a combined silicon and chromium content exceeding 80% to improve both production and performance remains a crucial research topic for those skilled in the art. Summary of the Invention

[0004] This invention provides a process for smelting silicon-chromium alloys using an oxygen-enriched top-bottom double-blowing method, which can significantly reduce carbon content, greatly increase silicon content, recycle fly ash, and produce high-grade silicon-chromium alloys with a total silicon-chromium content greater than 80%, thereby solving the problems existing in the aforementioned background technology.

[0005] To achieve the above objectives, the present invention provides a process for smelting silicon-chromium alloys using an oxygen-enriched top-bottom double-blowing method, comprising: S1 Pretreatment: Weigh silica, coke and high carbon ferrochrome by weight, and after crushing them separately, mix the above raw materials evenly. S2 smelting: The mixed raw materials are fed into an electric furnace and smelted to form molten steel. S3 blowing: The molten steel in the furnace is poured into the ladle, and a decarburizing agent is sprayed from the top of the ladle onto the surface of the molten steel. At the same time, oxygen is sprayed into the molten steel from the bottom of the ladle. S4 casting: After the oxygen injection is completed, the molten steel is slag-blocked and tapped into a fixed mold, then cooled and solidified to form a casting billet, thus obtaining silicon-chromium alloy.

[0006] The smelting method of this invention significantly reduces carbon content and improves the control precision of carbon content by comprehensively controlling smelting process parameters such as oxygen blowing volume and decarburizing agent dosage. Furthermore, the decarburizing agent greatly increases the silicon content in the silicon-chromium alloy, ensuring the stable production of high-grade silicon-chromium alloy. This method has outstanding advantages such as simple process technology, convenient production operation, recycling of fly ash, good energy saving and consumption reduction effect, and reduced production cost of silicon-chromium alloy. It has significant social environmental protection effects and economic benefits, and has a good prospect for promotion and application in the metallurgical industry.

[0007] The composition is further specified as follows: silica has a weight ratio of 290-310 parts, a particle size of 50-150 mm, and a SiO2 content of ≥98%; coke has a weight ratio of 160-170 parts, a particle size of 20-45 mm, and a carbon content of ≥85%; and high-carbon ferrochrome has a weight ratio of 105-110 parts, a particle size of 20-100 mm, and a chromium content of >65%.

[0008] The raw materials, silica and ferrochrome, are smelted under high temperature and strong oxidizing atmosphere. Coke is used as a reducing agent to reduce them to silicon and chromium, and release carbon monoxide and carbon dioxide, so that carbon leaves the molten steel in a gaseous form.

[0009] Further settings include a secondary operating voltage of 270-275V, a secondary operating current of 7800-8300A, and a smelting time of 3.5-4.5h.

[0010] Further configuration: the electric furnace uses three electrodes, and the diameter of the center circle formed by the three electrodes is less than 1.25d, where d is the electrode diameter.

[0011] Preferably, the diameter of the polar center circle formed by the three electrodes is 1.21-1.23d.

[0012] In this invention, the distance between the three electrodes of the electric furnace is appropriately reduced, resulting in a smaller electrode center circle diameter than in existing technologies (the normal electrode center circle diameter is 1.25d). Without affecting the charge melting capacity, this accelerates the arc ignition and heating of the charge, improves arc stability, and minimizes the overlap between the electrode reaction zones, achieving a more rational distribution of heat within the furnace. The molten pool temperature can reach over 1700℃, electrode consumption is reduced, and furnace conditions are stable and easily adjustable. The electric furnace uses electrical energy to convert into heat energy to melt metal and form molten steel, representing a clean energy application. Other structural and supporting facilities of the electric furnace are the same as in existing technologies and will not be limited or elaborated upon here.

[0013] Further settings include a decarbonizing agent and an oxygen-containing injection time of 8-13 minutes.

[0014] Further settings include: the decarbonizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%; the dosage of the decarbonizing agent is 28-35 kg / (t·min); the decarbonizing agent is assisted by oxygen injection, and the injection pressure of the oxygen-containing gas is 8-12 MPa.

[0015] The top lance position for injecting the decarburizing agent should be set so that the decarburizing agent can be sprayed onto the surface of the molten steel, preferably 500-800mm away from the molten steel surface. After the decarburizing agent is injected by the top lance and oxygen is blown by the bottom lance, the oxygen-containing gas has a certain convective stirring effect, promoting the chemical reaction between elements. The oxygen and decarburizing agent react with the carbon in the molten steel, which also leads to a certain degree of increase in the temperature of the molten steel. The ladle is open at the top, and the carbon monoxide and carbon dioxide generated by the reaction are directly volatilized and discharged from the molten steel. The decarburizing agent and oxygen make the removal of impurity elements (mainly carbon, and possibly phosphorus, sulfur, etc.) more thorough, resulting in a significant refining effect. The injection of fly ash and oxygen can be carried out using commonly used equipment in existing technology (such as oxygen blowing devices and oxygen lances).

[0016] In this invention, fly ash is added to molten steel as a decarburizing agent. Excess carbon in the steel is removed by the reaction of silicon oxides and iron oxides with carbon at high temperature. The carbon escapes as carbon monoxide gas, resulting in high decarburization efficiency. While achieving decarburization, no new impurities are introduced. Combined with oxygen blowing, the carbon content can be controlled below 0.03%, thereby precisely controlling the carbon content of the alloy and ensuring that it meets the composition standards required for smelting. Furthermore, since the main component of fly ash, SiO2, can be reduced to silicon, the silicon content in the finished alloy can be increased, improving the silicon recovery rate and realizing the resource utilization of waste. This opens up new avenues for the utilization of fly ash. Moreover, fly ash as a decarburizing agent is lower in cost than commonly used decarburizing agents, which has significant economic and environmental benefits and is in line with the green and low-carbon development direction. Fly ash can also prevent excessive oxygen blowing from causing steel over-oxidation. The unburned carbon in fly ash can compete with chromium and combine with oxygen, thus avoiding the oxidation of chromium in the steel and reducing the chromium recovery rate. The use of fly ash can reduce the amount of oxygen used for oxygen blowing, thereby saving energy, reducing production costs, improving product quality and increasing product added value.

[0017] A further step involves injecting oxygen-containing gas into the molten steel at the ladle outlet during the casting process. After decarburization, the molten steel is poured, and the continued injection of oxygen during casting further decarburizes and removes carbon, ultimately yielding a high-grade silicon-chromium alloy with a combined silicon and chromium content greater than 80%.

[0018] Further, the oxygen-containing components used in the decarburization and casting processes are the same, and the oxygen-containing gas is a mixture of pure oxygen and air, in which the volume ratio of pure oxygen is 30-50%.

[0019] Further settings include an oxygen supply intensity of 0.2-0.3 m³ / s (using a pure oxygen meter). 3 / (t·min). During the decarburization process, the oxygen content provides a certain stirring intensity to the molten steel, which improves the contact and mixing degree between fly ash and molten steel, thereby achieving the purpose of silicon reduction and decarburization. Controlling the gas supply intensity can avoid both insufficient oxygen supply, which would reduce the decarburization efficiency, and excessive oxygen supply, which would cause severe splashing of molten steel and slag, thus avoiding metal loss and ladle corrosion, and extending the service life of the equipment.

[0020] Further specified, in the silicon-chromium alloy, the sum of silicon and chromium content is greater than 80%, with chromium content not less than 30% and silicon content not less than 50%. Besides silicon and chromium, the remainder in the silicon-chromium alloy consists of iron, carbon, sulfur, and unavoidable residual elements. The Cr2O3 content in the slag and steel slag is <0.5%. The lower the degree of chromium oxidation in the slag, the higher the chromium recovery rate.

[0021] The process for smelting silicon-chromium alloys using the oxygen-enriched top-and-bottom double-blowing method provided by this invention has the following advantages and beneficial effects: 1) This smelting method reduces electrode consumption, stabilizes furnace conditions, and makes them easy to adjust by comprehensively controlling smelting process parameters such as electrode center circle diameter, oxygen blowing amount, and decarburizing agent dosage, without affecting the material processing capacity. Furthermore, by combining oxygen blowing and decarburizing agent blowing at the top and bottom of the molten steel, the carbon content is significantly reduced, improving the control accuracy of carbon content and resulting in a significant refining effect.

[0022] 2) This method removes excess carbon from molten steel using a decarburizing agent, achieving high decarburization efficiency and controlling the carbon content below 0.03%. It also significantly increases the silicon content in the silicon-chromium alloy, ensuring the stable production of high-grade silicon-chromium alloy with a combined silicon-chromium content greater than 80%. The silicon recovery rate is improved, and it also avoids excessive oxygen blowing that could cause over-oxidation of the molten steel, reducing the amount of oxygen used for oxygen blowing. This achieves the goals of saving energy, reducing production costs, improving product quality, and increasing product added value.

[0023] 3) This method has the outstanding advantages of simple process technology, convenient production operation, recycling of fly ash, good energy saving and consumption reduction effect, and reduced production cost of silicon-chromium alloy. It realizes the resource utilization of waste, opens up a new way for the utilization of fly ash, and fly ash as a decarbonizing agent is cheaper than the commonly used decarbonizing agents. It has significant social environmental protection effect and economic benefits, conforms to the green and low-carbon development direction, and has a good prospect for promotion and application in the metallurgical industry. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of the present invention.

[0025] The following examples use conventional instruments and equipment in the art. Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available and conform to conventional specifications in the art. Any techniques or conditions not specifically described in the following examples can be performed according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0026] It should be noted that, in this invention and the following embodiments, unless otherwise specified, concentration, ratio, etc. are all weight concentration, weight ratio, etc., "%" all represent weight percentage, and "parts" all represent weight parts. These are common writing habits used by those skilled in the art, and therefore will not be repeated in this invention.

[0027] As a preferred embodiment, the present invention provides a process for smelting silicon-chromium alloys using an oxygen-enriched top-bottom double-blowing method, and the specific process steps are as follows: S1 Pretreatment: Weigh silica, coke and high-carbon ferrochrome by weight, and after crushing them separately, mix the above raw materials evenly.

[0028] The silica comprises 290-310 parts by weight, with a particle size of 50-150 mm, and a SiO2 content ≥98%. The coke comprises 160-170 parts by weight, with a particle size of 20-45 mm, and a carbon content ≥85%. The high-carbon ferrochrome comprises 105-110 parts by weight, with a particle size of 20-100 mm, and a chromium content >65%.

[0029] S2 smelting: The mixed raw materials are fed into an electric furnace and smelted to form molten steel.

[0030] The secondary operating voltage of the aforementioned electric furnace is 270-275V, the secondary operating current is 7800-8300A, and the smelting time is 3.5-4.5h. The electric furnace uses three electrodes, and the diameter of the central circle formed by the three electrodes is <1.25d, where d is the electrode diameter. Preferably, the diameter of the central circle formed by the three electrodes is 1.21-1.23d.

[0031] It should be noted that the electrode diameter used in the embodiment is 850mm, but those skilled in the art can choose the appropriate electrode diameter according to production volume, electric furnace molten pool volume, etc.

[0032] S3 blowing: Molten steel is poured from the furnace into a ladle. A decarburizing agent is sprayed onto the surface of the molten steel from above the ladle, while oxygen is simultaneously sprayed into the molten steel from the bottom of the ladle. The spraying time for both the decarburizing agent and the oxygen is 8-13 minutes.

[0033] The decarbonizing agent is fly ash, with a SiO2 content of not less than 50% and an Fe2O3 content of not less than 20%. The dosage of the decarbonizing agent is 28-35 kg / (t·min). The decarbonizing agent is assisted by oxygen injection, with an oxygen injection pressure of 8-12 MPa.

[0034] S4 Casting: After oxygen injection, molten steel at a temperature of 1500-1650℃ is tapped through a slag-blocking process, poured into a fixed mold, and cooled and solidified to form a cast billet, thus obtaining the silicon-chromium alloy. During the casting process, oxygen is injected into the poured molten steel at the outlet of the ladle.

[0035] The oxygen-containing gas used in the above decarburization and casting processes has the same composition: a mixture of pure oxygen and air, with pure oxygen accounting for 30-50% by volume. The oxygen supply intensity, measured in pure oxygen, is 0.2-0.3 m³ / s. 3 / (t·min).

[0036] The present invention will be further described in detail below with reference to embodiments. However, it should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1

[0037] A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method includes the following steps: 1) Weigh silica, coke, and high-carbon ferrochrome according to parts by weight, and after pulverizing them separately, mix the above raw materials evenly. The silica shall be 290 parts by weight, with a particle size of 50-150 mm and a SiO2 content ≥98%. The coke shall be 160 parts by weight, with a particle size of 20-45 mm and a carbon content ≥85%. The high-carbon ferrochrome shall be 105 parts by weight, with a particle size of 20-100 mm and a chromium content >65%.

[0038] 2) The mixed raw materials are fed into an electric furnace and smelted to form molten steel. The secondary operating voltage of the electric furnace is 270V, the secondary operating current is 7800A, and the smelting time is 4.5h. The electric furnace uses three electrodes, and the diameter of the central circle formed by the three electrodes is 1.21d, where d is the electrode diameter.

[0039] 3) Pour the molten steel from the furnace into the ladle. Spray a decarburizing agent onto the surface of the molten steel from above the ladle, while simultaneously spraying oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time for both the decarburizing agent and the oxygen-containing gas is 8 minutes. The decarburizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%. The dosage of the decarburizing agent is 28 kg / (t·min). The decarburizing agent is assisted by oxygen-containing gas injection at a pressure of 8 MPa.

[0040] 4) After the oxygen injection is completed, the molten steel at a temperature of 1500-1650℃ is tapped with slag and poured into a fixed mold. After cooling and solidification, a cast billet is formed, which yields the silicon-chromium alloy. During the casting process, oxygen is injected into the molten steel poured out at the outlet of the ladle.

[0041] The oxygen-containing gas used in the above decarburization and casting processes has the same composition: a mixture of pure oxygen and air, with pure oxygen accounting for 30% by volume. The oxygen supply intensity, measured in pure oxygen, is 0.2 m³ / s. 3 / (t·min). Example 2

[0042] A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method includes the following steps: 1) Weigh silica, coke, and high-carbon ferrochrome according to their respective weight parts. After pulverizing each component separately, mix the raw materials thoroughly. The silica should be 310 parts by weight, with a particle size of 50-150 mm and a SiO2 content ≥98%. The coke should be 170 parts by weight, with a particle size of 20-45 mm and a carbon content ≥85%. The high-carbon ferrochrome should be 110 parts by weight, with a particle size of 20-100 mm and a chromium content >65%.

[0043] 2) The mixed raw materials are fed into an electric furnace and smelted to form molten steel. The secondary operating voltage of the electric furnace is 275V, the secondary operating current is 8300A, and the smelting time is 4.5h. The electric furnace uses three electrodes, and the diameter of the central circle formed by the three electrodes is 1.23d, where d is the electrode diameter.

[0044] 3) Pour the molten steel from the furnace into the ladle. Spray a decarburizing agent onto the surface of the molten steel from above the ladle, while simultaneously spraying oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time for both the decarburizing agent and the oxygen-containing gas is 13 minutes. The decarburizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%. The dosage of the decarburizing agent is 35 kg / (t·min). The decarburizing agent is sprayed with oxygen-containing gas at a pressure of 12 MPa.

[0045] 4) After the oxygen injection is completed, the molten steel at a temperature of 1500-1650℃ is tapped with slag and poured into a fixed mold. After cooling and solidification, a cast billet is formed, which yields the silicon-chromium alloy. During the casting process, oxygen is injected into the molten steel poured out at the outlet of the ladle.

[0046] The oxygen-containing gas used in the above decarburization and casting processes has the same composition: a mixture of pure oxygen and air, with pure oxygen accounting for 50% by volume. The oxygen supply intensity, measured in pure oxygen, is 0.3 m³ / s. 3 / (t·min). Example 3

[0047] A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method includes the following steps: 1) Weigh silica, coke, and high-carbon ferrochrome according to parts by weight, and after pulverizing them separately, mix the above raw materials evenly. The silica shall be 300 parts by weight, with a particle size of 50-150 mm and a SiO2 content ≥98%. The coke shall be 165 parts by weight, with a particle size of 20-45 mm and a carbon content ≥85%. The high-carbon ferrochrome shall be 108 parts by weight, with a particle size of 20-100 mm and a chromium content >65%.

[0048] 2) The mixed raw materials are fed into an electric furnace and smelted to form molten steel. The secondary operating voltage of the electric furnace is 273V, the secondary operating current is 8000A, and the smelting time is 4 hours. The electric furnace uses three electrodes, and the diameter of the central circle formed by the three electrodes is 1.22d, where d is the electrode diameter.

[0049] 3) Pour the molten steel from the furnace into the ladle. Spray a decarburizing agent onto the surface of the molten steel from above the ladle, while simultaneously spraying oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time for both the decarburizing agent and the oxygen-containing gas is 10 minutes. The decarburizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%. The dosage of the decarburizing agent is 30 kg / (t·min). The decarburizing agent is sprayed with oxygen-containing gas at a pressure of 10 MPa.

[0050] 4) After the oxygen injection is completed, the molten steel at a temperature of 1500-1650℃ is tapped with slag and poured into a fixed mold. After cooling and solidification, a cast billet is formed, which yields the silicon-chromium alloy. During the casting process, oxygen is injected into the molten steel poured out at the outlet of the ladle.

[0051] The oxygen-containing gas used in the above decarburization and casting processes has the same composition: a mixture of pure oxygen and air, with pure oxygen accounting for 40% by volume. The oxygen supply intensity, measured in pure oxygen, is 0.2 m³ / s. 3 / (t·min). Example 4

[0052] A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method includes the following steps: 1) Weigh silica, coke, and high-carbon ferrochrome according to their respective weight parts. After pulverizing each component separately, mix the raw materials thoroughly. The silica should be 305 parts by weight, with a particle size of 50-150 mm and a SiO2 content ≥98%. The coke should be 165 parts by weight, with a particle size of 20-45 mm and a carbon content ≥85%. The high-carbon ferrochrome should be 110 parts by weight, with a particle size of 20-100 mm and a chromium content >65%.

[0053] 2) The mixed raw materials are fed into an electric furnace and smelted to form molten steel. The secondary operating voltage of the electric furnace is 272V, the secondary operating current is 8100A, and the smelting time is 4 hours. The electric furnace uses three electrodes, and the diameter of the central circle formed by the three electrodes is 1.23d, where d is the electrode diameter.

[0054] 3) Pour the molten steel from the furnace into the ladle. Spray a decarburizing agent onto the surface of the molten steel from above the ladle, while simultaneously spraying oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time for both the decarburizing agent and the oxygen-containing gas is 12 minutes. The decarburizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%. The dosage of the decarburizing agent is 33 kg / (t·min). The decarburizing agent is sprayed with oxygen-containing gas at a pressure of 10 MPa.

[0055] 4) After the oxygen injection is completed, the molten steel at a temperature of 1500-1650℃ is tapped with slag and poured into a fixed mold. After cooling and solidification, a cast billet is formed, which yields the silicon-chromium alloy. During the casting process, oxygen is injected into the molten steel poured out at the outlet of the ladle.

[0056] The oxygen-containing gas used in the above decarburization and casting processes has the same composition: a mixture of pure oxygen and air, with pure oxygen accounting for 50% by volume. The oxygen supply intensity, measured in pure oxygen, is 0.3 m³ / s. 3 / (t·min).

[0057] Comparative Example 1: A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method, differing from Example 4 only in the following steps: 3) Pour the molten steel from the furnace into the ladle. Simultaneously, spray oxygen-containing gas onto the surface of the molten steel from the top of the ladle, and simultaneously spray oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time for both the top and bottom is 12 minutes. The spraying pressure for the top is 10 MPa. That is, no decarburizing agent (fly ash) is sprayed onto the surface of the ladle.

[0058] Comparative Example 2: A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method, differing from Example 4 only in the following steps: 3) Pour the molten steel from the furnace into a ladle. After the temperature drops to 1500-1650℃, remove the molten steel by slag removal, pour it into a fixed mold, and allow it to cool and solidify to form a billet, thus obtaining the silicon-chromium alloy. That is, the molten steel is not subjected to decarburizing agent or oxygen injection.

[0059] The finished silicon-chromium alloys produced in the examples and comparative examples were tested for their chemical composition mass fractions using the methods in GB / T4009-2008 "Silicon-Chromium Alloys". Each test sample group had three replicates, and the average value was taken. The results are shown in Table 1.

[0060] Table 1 (Unit: %)

[0061] As shown in the table above, the smelting method of this invention, due to the injection of fly ash, increases the silicon content in the finished alloy from over 40% to over 50% compared to ordinary alloys, and further reduces the carbon content to below 0.03%. It also slightly affects the reduction of other impurities, resulting in a significant improvement in the grade and quality of the finished alloy. In Comparative Example 1, since no fly ash was injected, the silicon content in the finished alloy was significantly reduced, and the carbon content was slightly increased, but the quality was still acceptable and could be classified as FeCr30Si40-C. In Comparative Example 2, since neither fly ash nor oxygen was injected, the silicon content decreased while the carbon content increased significantly, classifying it as FeCr30Si40-D, but its quality was clearly inferior to the finished alloys of the embodiments. It is evident that injecting fly ash has a significant beneficial effect on decarburization, silicon enhancement, and alloy quality improvement, providing a new utilization pathway for fly ash.

[0062] It should be noted that some detailed steps of the operation are not described in this invention, but are prior art known to those skilled in the art, and therefore will not be repeated here. Furthermore, in this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. In this invention, not all possible combinations of the various technical features in each embodiment or implementation are described. As long as the combinations of these technical features do not contradict each other, the various technical features in each embodiment or implementation can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for smelting silicon-chromium alloys using an oxygen-enriched top-and-bottom double-blowing method, characterized in that, include: S1 Pretreatment: Weigh silica, coke and high carbon ferrochrome by weight, and after crushing them separately, mix the above raw materials evenly. S2 smelting: The mixed raw materials are fed into an electric furnace and smelted to form molten steel. S3 blowing: Molten steel is poured into a ladle, and a decarburizing agent is sprayed onto the surface of the molten steel from above the ladle, while oxygen is simultaneously sprayed into the molten steel from the bottom of the ladle; the spraying time for both the decarburizing agent and the oxygen is 8-13 minutes; the decarburizing agent is fly ash, with a SiO2 content of not less than 50% and a Fe2O3 content of not less than 20%; the dosage of the decarburizing agent is 28-35 kg / (t·min); the decarburizing agent is assisted by oxygen injection, and the oxygen injection pressure is 8-12 MPa; S4 casting: After the oxygen injection is completed, the molten steel is slag-blocked and tapped into a fixed mold, then cooled and solidified to form a billet, which is the silicon-chromium alloy. In the silicon-chromium alloy, the sum of silicon and chromium content is greater than 80%, of which chromium content is not less than 30% and silicon content is not less than 50%.

2. The process for smelting silicon-chromium alloy using the oxygen-enriched top-bottom double-blowing method according to claim 1, characterized in that, The silica has a weight of 290-310 parts, a particle size of 50-150 mm, and a SiO2 content of ≥98%; the coke has a weight of 160-170 parts, a particle size of 20-45 mm, and a carbon content of ≥85%; and the high-carbon ferrochrome has a weight of 105-110 parts, a particle size of 20-100 mm, and a chromium content of >65%.

3. The process for smelting silicon-chromium alloys using the oxygen-enriched top-bottom double-blowing method according to claim 1, characterized in that, The electric furnace has a secondary operating voltage of 270-275V, a secondary operating current of 7800-8300A, and a smelting time of 3.5-4.5h.

4. The process for smelting silicon-chromium alloy using the oxygen-enriched top-bottom double-blowing method according to claim 3, characterized in that, The electric furnace uses three electrodes, and the diameter of the center circle formed by the three electrodes is less than 1.25d, where d is the electrode diameter.

5. The process for smelting silicon-chromium alloys using the oxygen-enriched top-and-bottom double-blowing method according to claim 1, characterized in that, During the casting process, oxygen-containing air is injected into the molten steel poured out at the outlet of the ladle.

6. The process for smelting silicon-chromium alloys using the oxygen-enriched top-and-bottom double-blowing method according to claim 5, characterized in that, The oxygen-containing components used in the decarburization and casting processes are the same, and the oxygen-containing gas is a mixture of pure oxygen and air, wherein the volume ratio of pure oxygen is 30-50%.

7. The process for smelting silicon-chromium alloys using the oxygen-enriched top-and-bottom double-blowing method according to claim 6, characterized in that, The oxygen supply intensity, measured using a pure oxygen meter, is 0.2-0.3 m³ / s. 3 / (t·min).

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