Process for smelting silicon-chromium alloy by oxygen-enriched top and bottom blowing

Abstract

The present application provides a kind of process for smelting silicon-chromium alloy by oxygen-enriched top and bottom blowing method, belongs to alloy smelting technical field, comprising: S1 pretreatment: according to weight portion, take silica, coke and high-carbon ferrochrome, after being pulverized respectively, the above production raw materials are mixed uniformly;S2 smelting: the mixed production raw materials are sent into electric furnace, and power smelting forms molten steel;S3 blowing: the molten steel in furnace is poured into ladle, and carbon removal agent is sprayed on the surface of molten steel in the direction of ladle, while oxygen-containing gas is sprayed into molten steel from the bottom of ladle;S4 casting: after oxygen-containing gas spraying is finished, the molten steel is stopped with slag, and after being poured into fixed mold, it is cooled and solidified to form casting blank, and silicon-chromium alloy is obtained.The method significantly reduces carbon content, improves the control precision of carbon content, and through carbon removal agent, the silicon content in silicon-chromium alloy is greatly improved, to ensure stable production of high-grade silicon-chromium alloy, to open up a new way for the use of fly ash, and to reduce the production cost of silicon-chromium alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy smelting, and particularly relates to a process for smelting silicon-chromium alloy by adopting oxygen-enriched top and bottom blowing method. BACKGROUND

[0002] Silicon-chromium alloy is an iron alloy made of silicon (Si) and chromium (Cr) mixed in a certain proportion, which contains a high proportion of chromium and silicon, and usually contains a small amount of carbon (C) and other elements. The alloy is silver-gray in appearance 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, and can also reduce the thermal expansion coefficient of steel 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, and can also improve the high temperature performance of steel, so that it can withstand higher temperatures, and different proportions of silicon and chromium will significantly affect the performance of the alloy. Silicon-chromium alloy can be used as a deoxidizer in steel smelting, which can effectively remove oxygen molecules in molten steel, and can also be used for carbon enrichment and adjustment of steel composition; it is also a key additive for producing stainless steel, which can improve its corrosion resistance, heat resistance and hardness; it can also be used as a casting modifier to improve the fluidity of molten iron and reduce casting defects, so that the steel contains stable silicon and chromium elements, thereby improving the mechanical properties, wear resistance and oxidation resistance of the steel, and compared with pure chromium metal, the alloy form is more economical and practical, which can reduce production cost.

[0003] The existing production method of silicon-chromium alloy is relatively mature, but the sum of silicon and chromium content in the produced silicon-chromium alloy is usually only greater than 70%, which meets the industry and standard requirements, but the overall production quality is still poor, and there is still room for improvement. Therefore, smelting and producing a silicon-chromium alloy with a sum of silicon and chromium content of more than 80% to improve its production quality and use quality is still one of the important topics that technicians in the field need to research and develop. SUMMARY

[0004] The present application provides a process for smelting silicon-chromium alloy by adopting oxygen-enriched top and bottom blowing method, which can significantly reduce the carbon content, greatly increase the silicon content, recycle fly ash, and produce high-grade silicon-chromium alloy with a sum of silicon and chromium content of more than 80%, to solve the problems in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides a process for smelting silicon-chromium alloy by adopting oxygen-enriched top and bottom blowing method, which comprises:

[0006] S1 pretreatment: weigh the silica, coke and high-carbon chromium iron by weight parts, and mix the above production raw materials uniformly after being crushed respectively;

[0007] S2 smelting: the mixed production raw materials are sent into an electric furnace, and electric smelting is performed to form molten steel;

[0008] S3 blowing: the molten steel in the furnace is poured into a ladle, and a decarburization agent is sprayed on the surface of the molten steel in the upward direction of the ladle, and oxygen-containing gas is sprayed into the molten steel from the bottom of the ladle;

[0009] S4 casting: after the oxygen-containing gas spraying is completed, the molten steel is subjected to slag blocking and tapping, and is poured into a fixed mold to cool and solidify to form a casting blank, thereby obtaining a silicon-chromium alloy.

[0010] The smelting method of the present application significantly reduces the carbon content by comprehensively controlling the oxygen blowing amount, the decarburization agent amount and other smelting process parameters, improves the control precision of the carbon content, and significantly increases the silicon content in the silicon-chromium alloy through the decarburization agent, thereby ensuring the stable production of high-grade silicon-chromium alloy. The method has the outstanding advantages of simple process technology, convenient production operation, recycling of fly ash, good energy saving and consumption reduction effect, and reduction of the production cost of silicon-chromium alloy, has significant social environmental protection effect and economic benefit, and has good popularization and application prospect in the metallurgical industry.

[0011] Further, the weight of the silica is 290-310 parts, the particle size is 50-150 mm, and the SiO2 content is ≥98%; the weight of the coke is 160-170 parts, the particle size is 20-45 mm, and the carbon content is ≥85%; and the weight of the high-carbon chromium iron is 105-110 parts, the particle size is 20-100 mm, and the chromium content is >65%.

[0012] The silica and chromium iron in the production raw materials are smelted under high temperature and strong oxidizing atmosphere conditions, and silicon and chromium are obtained by reduction with coke as a reducing agent, and carbon monoxide and carbon dioxide are released, so that carbon leaves the molten steel in the form of gas.

[0013] Further, the secondary working voltage of the electric furnace is 270-275 V, the secondary working current is 7800-8300 A, and the smelting time is 3.5-4.5 h.

[0014] Further, the electric furnace adopts three electrodes, and the diameter of the pole core circle formed by the three electrodes is <1.25d, where d is the electrode diameter.

[0015] Preferably, the diameter of the pole core circle formed by the three electrodes is 1.21-1.23d.

[0016] The electrode spacing of the three electrodes of the electric furnace is appropriately reduced in the application, so that the polar core diameter is smaller than that in the prior art (the normal polar core diameter is 1.25d), the arcing and temperature rising of the furnace charge are accelerated, the stability of the electric arc is improved, the reaction zones of the electrodes are connected with each other and the minimum overlapping part is realized, the heat in the furnace is reasonably distributed, the temperature of the molten pool in the furnace can reach more than 1700℃, the electrode consumption is reduced, the furnace condition is stable and easy to adjust. The electric furnace converts electric energy into heat energy to melt metal to form molten steel, which belongs to the application of clean energy. The other structures and supporting facilities of the electric furnace are the same as those in the prior art, which will not be limited and described here.

[0017] Further, the blowing time of the carbon removal agent and the oxygen-containing gas is 8-13 min.

[0018] Further, the carbon removal agent is fly ash, the content of SiO2 in the fly ash is not less than 50%, and the content of Fe2O3 is not less than 20%; the amount of the carbon removal agent is 28-35 kg / (t·min); the carbon removal agent is blown with oxygen-containing gas, and the blowing pressure of the oxygen-containing gas is 8-12 MPa.

[0019] The top gun position for blowing the carbon removal agent is set to be able to blow the carbon removal agent to the surface of the molten steel, and preferably 500-800 mm away from the surface of the molten steel. After blowing the carbon removal agent by the top gun and blowing oxygen by the bottom gun, the oxygen-containing gas has a certain convection stirring effect, which promotes the chemical reaction between elements. The oxygen and the carbon removal agent react with carbon in the molten steel, which also causes the temperature of the molten steel to rise to a certain extent. The upper part of the ladle is open, and the generated carbon monoxide and carbon dioxide are directly volatilized and discharged from the molten steel. The carbon removal agent and oxygen make the removal of impurity elements (mainly carbon, and possibly phosphorus, sulfur, etc.) more thorough, and the refining effect is remarkable. The blowing of fly ash and oxygen-containing gas can use the equipment (such as oxygen blowing device and oxygen blowing gun) commonly used in the prior art.

[0020] In the application, fly ash is added to molten steel as decarburizer, and the excessive carbon component in the molten steel is removed by the reaction of silicon oxide and iron oxide with carbon at high temperature, and the carbon escapes in the form of carbon monoxide gas, so that the decarburization efficiency is high, and new impurities are not introduced while achieving the purpose of decarburization, and the carbon content can be controlled below 0.03% by cooperating with oxygen blowing, so as to accurately control the carbon content of the alloy, ensure that it reaches the required component standard of smelting, and even because the main component SiO2 in fly ash can be reduced to silicon, the silicon content in the finished alloy can be increased, the silicon recovery rate is improved, the resource utilization of waste is realized, a new way for the utilization of fly ash is opened up, and the fly ash as a decarburizer has lower cost than the existing common decarburizers, has remarkable economic and environmental protection significance, and meets the development direction of green and low carbon. The fly ash can also avoid over-oxidation of the molten steel caused by excessive oxygen blowing, and the unburned carbon in the fly ash can combine with oxygen to compete with chromium, thereby avoiding the oxidation of chromium in the molten steel and reducing the problem of reducing the chromium recovery rate. The use of fly ash can reduce the oxygen consumption of oxygen blowing, achieve the purpose of saving energy consumption, reducing production cost, improving product quality and increasing product added value.

[0021] Further provided is that during the casting process, oxygen-containing gas is sprayed at the water outlet of the ladle to the poured molten steel. After decarburization, the molten steel is poured, and the oxygen-containing gas is continuously sprayed during the casting process to further decarburize and remove carbon, and finally a high-grade silicon-chromium alloy with a silicon-chromium content greater than 80% is obtained.

[0022] Further provided is that the oxygen-containing gas composition used during decarburization and casting is the same, and the oxygen-containing gas is a mixture of pure oxygen and air, wherein the volume percentage of pure oxygen is 30-50%.

[0023] Further provided is that the oxygen-containing gas supply intensity is 0.2-0.3 m 3 / (t·min) in terms of pure oxygen. During the decarburization process, the oxygen-containing gas provides a certain stirring intensity to the molten steel, improves the contact and mixing degree of fly ash and molten steel, achieves the purpose of reducing silicon and decarburization, and controls the gas supply intensity to avoid too low oxygen supply to reduce the decarburization efficiency, and too high oxygen supply to cause serious molten steel and slag spatter, thereby avoiding metal loss and ladle erosion, and prolonging the service life of the equipment.

[0024] Further provided is that in the silicon-chromium alloy, the sum of the contents of silicon and chromium is greater than 80%, wherein the chromium content is not less than 30%, and the silicon content is not less than 50%. In the silicon-chromium alloy, in addition to silicon and chromium, the balance is iron, carbon, sulfur and unavoidable residual elements, the content of Cr2O3 in the slag and steel slag is <0.5%, and the lower the oxidation degree of chromium in the slag, the higher the chromium recovery rate.

[0025] The process for smelting silicon-chromium alloy by using the oxygen-enriched top and bottom blowing method provided by the application has the following advantages and beneficial effects:

[0026] 1) The smelting method reduces the electrode consumption of the electric furnace, stabilizes the furnace condition and is easy to adjust by comprehensively controlling the electrode core circle diameter, oxygen blowing amount, carbon removal agent amount and other smelting process parameters without affecting the material melting capacity, and significantly reduces the carbon content by cooperating with oxygen blowing at the top and bottom of the molten steel and blowing the carbon removal agent, improves the control precision of the carbon content, and the refining effect is remarkable.

[0027] 2) The method removes the excess carbon components in the molten steel by the carbon removal agent, has high decarburization efficiency, controls the carbon content below 0.03%, greatly increases the silicon content in the silicon-chromium alloy, ensures stable production of high-grade silicon-chromium alloy with the sum of silicon-chromium content greater than 80%, improves the silicon recovery rate, avoids excessive oxygen blowing of the molten steel, reduces the oxygen amount used for oxygen blowing, achieves the purposes of saving energy consumption, reducing production cost, improving product quality and increasing product added value.

[0028] 3) The method has the outstanding advantages of simple process technology, convenient production operation, good energy saving and consumption reduction effect, and low production cost of the silicon-chromium alloy, realizes the resource utilization of waste, opens up a new way for the utilization of fly ash, and the fly ash as the carbon removal agent has lower cost than the existing commonly used carbon removal agents, has significant social environmental protection effect and economic benefit, conforms to the development direction of green and low carbon, and has good popularization and application prospect in the metallurgical industry. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also belong to the scope of protection of the present application.

[0030] In the following embodiments, conventional instruments and equipment in the art are used. The test materials and reagents used in the following embodiments, unless otherwise specified, can be obtained from commercial channels, and the specifications are conventional specifications in the art. If the specific technology or condition is not specified in the following embodiments, it can be carried out according to the technology or condition described in the literature in the art or according to the product instruction.

[0031] It should be noted that in the present application and the following embodiments, the concentration, ratio and the like not specially specified are weight concentration, weight ratio and the like, and "%" represents weight percentage, and "parts" represents weight parts, which are the writing habits commonly used by those skilled in the art, and therefore will not be described in detail in the present application.

[0032] As a preferred embodiment, the present application provides a process for smelting silicon-chromium alloy by using oxygen-enriched top and bottom combined blowing method, and the specific process steps are as follows:

[0033] S1 Pretreatment: The silica, coke and high-carbon chromium iron are weighed by weight parts, and after being crushed respectively, the above production raw materials are mixed uniformly.

[0034] The weight part of the above-mentioned silica is 290-310 parts, the particle size is 50-150 mm, and the SiO2 content is ≥98%. The weight part of the coke is 160-170 parts, the particle size is 20-45 mm, and the carbon content is ≥85%. The weight part of the high-carbon chromium iron is 105-110 parts, the particle size is 20-100 mm, and the chromium content is >65%.

[0035] S2 Smelting: The mixed production raw materials are sent into the electric furnace, and the electric smelting is carried out to form molten steel.

[0036] The secondary working voltage of the above-mentioned electric furnace is 270-275 V, the secondary working current is 7800-8300 A, and the smelting time is 3.5-4.5 h. The electric furnace uses three electrodes, and the diameter of the pole core circle formed by the three electrodes is <1.25d, d is the diameter of the electrode. Preferably, the diameter of the pole core circle formed by the three electrodes is 1.21-1.23d.

[0037] It should be noted that the electrode diameter used in the examples is 850 mm, but those skilled in the art can select the appropriate electrode diameter according to the production capacity, the volume of the electric furnace molten pool, etc.

[0038] S3 blowing: The molten steel in the furnace is poured into a ladle, and the decarburizing agent is sprayed onto the surface of the molten steel from the top of the ladle, and oxygen-containing gas is sprayed into the molten steel from the bottom of the ladle. The spraying time of the decarburizing agent and the oxygen-containing gas is 8-13 min.

[0039] The decarburizing agent is fly ash, and the SiO2 content in the fly ash is not less than 50%, and the Fe2O3 content is not less than 20%. The amount of the decarburizing agent is 28-35 kg / (t·min). The decarburizing agent is sprayed with the aid of oxygen-containing gas, and the spraying pressure of the oxygen-containing gas is 8-12 MPa.

[0040] S4 Casting: After the oxygen-containing gas spraying is completed, the molten steel with a temperature of 1500-1650℃ is tapped with slag stopping, poured into a fixed mold and cooled to form a cast blank, and the silicon-chromium alloy is obtained. During the casting process, the molten steel poured out is sprayed with oxygen-containing gas at the water outlet of the ladle.

[0041] The oxygen-containing gas used in the above decarburization and casting process has the same composition, and the oxygen-containing gas is a mixture of pure oxygen and air, wherein the volume fraction of pure oxygen is 30-50%. The oxygen-containing gas supply intensity is 0.2-0.3 m 3(t·min).

[0042] The application will be further described in detail in connection with the following examples. However, it should be understood that the examples are for illustrative purposes only and are not intended to limit the scope of the application. Example 1

[0043] A process for smelting silicon-chromium alloy by using oxygen-enriched top and bottom double blowing method, comprising the following steps:

[0044] 1) The silica, coke and high-carbon ferrochrome are weighed by weight parts, and after being crushed respectively, the above production raw materials are mixed uniformly. The weight part of the above silica is 290 parts, the particle size is 50-150 mm, and the content of SiO2 therein is ≥98%. The weight part of the coke is 160 parts, the particle size is 20-45 mm, and the content of carbon therein is ≥85%. The weight part of the high-carbon ferrochrome is 105 parts, the particle size is 20-100 mm, and the content of chromium therein is >65%.

[0045] 2) The mixed production raw materials are sent into an electric furnace, and power is supplied to smelt molten steel. The secondary working voltage of the above electric furnace is 270 V, the secondary working current is 7800 A, and the smelting time is 4.5 h. The electric furnace adopts three electrodes, and the diameter of the pole core circle formed by the three electrodes is 1.21d, d being the electrode diameter.

[0046] 3) The molten steel in the furnace is poured into a ladle, and a decarburization agent is sprayed onto the surface of the molten steel from the top of the ladle, and oxygen-containing gas is sprayed into the molten steel from the bottom of the ladle. The spraying time of the decarburization agent and the oxygen-containing gas is 8 min. The decarburization agent is fly ash, the content of SiO2 in the fly ash is not less than 50%, and the content of Fe2O3 is not less than 20%. The amount of the decarburization agent is 28 kg / (t·min). The decarburization agent is sprayed with the aid of oxygen-containing gas, and the spraying pressure of the oxygen-containing gas is 8 MPa.

[0047] 4) After the oxygen-containing gas spraying is completed, the molten steel with a temperature of 1500-1650℃ is stopped with slag, and is poured into a fixed mold to cool and solidify to form a cast blank, thereby obtaining a silicon-chromium alloy. During the pouring process, the molten steel poured out is sprayed with oxygen-containing gas at the water outlet of the ladle.

[0048] The oxygen-containing gas used in the above decarburization and pouring processes has the same composition, and the oxygen-containing gas is a mixture of pure oxygen and air, wherein the volume ratio of pure oxygen is 30%. The oxygen-containing gas supply intensity is 0.2 m 3 (t·min). Example 2

[0049] A process for smelting silicon-chromium alloy by using oxygen-enriched top and bottom double blowing method, comprising the following steps:

[0050] 1) The silicon stone, coke and high-carbon chromium iron are weighed by weight parts, and after being crushed respectively, the above production raw materials are mixed uniformly. The weight part of the above-mentioned silicon stone is 310 parts, the particle size is 50-150 mm, and the content of SiO2 therein is ≥98%. The weight part of the coke is 170 parts, the particle size is 20-45 mm, and the content of carbon therein is ≥85%. The weight part of the high-carbon chromium iron is 110 parts, the particle size is 20-100 mm, and the content of chromium therein is >65%.

[0051] 2) The mixed production raw materials are sent into an electric furnace, and the electric smelting is carried out to form molten steel. The secondary working voltage of the electric furnace is 275 V, the secondary working current is 8300 A, and the smelting time is 4.5 h. The electric furnace adopts three electrodes, and the diameter of the pole core circle formed by the three electrodes is 1.23d, d is the electrode diameter.

[0052] 3) The molten steel in the furnace is poured into a ladle, and a decarburizer is sprayed onto the surface of the molten steel from the top of the ladle, and oxygen-containing gas is sprayed into the molten steel from the bottom of the ladle. The spraying time of the decarburizer and the oxygen-containing gas is 13 min. The decarburizer is fly ash, the content of SiO2 in the fly ash is not less than 50%, and the content of Fe2O3 is not less than 20%. The amount of the decarburizer is 35 kg / (t·min). The decarburizer is sprayed with the aid of oxygen-containing gas, and the spraying pressure of the oxygen-containing gas is 12 MPa.

[0053] 4) After the oxygen-containing gas spraying is completed, the molten steel with a temperature of 1500-1650℃ is discharged with slag blocking, and is poured into a fixed mold to cool and solidify to form a cast blank, thereby obtaining a silicon-chromium alloy. During the pouring process, the molten steel poured out is sprayed with oxygen-containing gas at the water outlet of the ladle.

[0054] The oxygen-containing gas compositions used in the above decarburization and pouring processes are the same, and the oxygen-containing gas is a mixed gas of pure oxygen and air, wherein the volume ratio of pure oxygen is 50%. The oxygen-containing gas supply intensity is 0.3 m 3 / (t·min) in terms of pure oxygen. Example 3

[0055] A process for smelting a silicon-chromium alloy by using an oxygen-enriched top and bottom blowing method, comprising the following steps:

[0056] 1) The silicon stone, coke and high-carbon chromium iron are weighed by weight parts, and after being crushed respectively, the above production raw materials are mixed uniformly. The weight part of the above-mentioned silicon stone is 310 parts, the particle size is 50-150 mm, and the content of SiO2 therein is ≥98%. The weight part of the coke is 170 parts, the particle size is 20-45 mm, and the content of carbon therein is ≥85%. The weight part of the high-carbon chromium iron is 110 parts, the particle size is 20-100 mm, and the content of chromium therein is >65%.

[0057] 2) The mixed production materials are sent into the electric furnace to form molten steel by electric smelting. The secondary working voltage of the electric furnace is 273 V, the secondary working current is 8000 A, and the smelting time is 4 h. The electric furnace adopts three electrodes, and the diameter of the pole core circle formed by the three electrodes is 1.22d, d being the electrode diameter.

[0058] 3) The molten steel in the furnace is poured into a ladle, and a decarburization agent is sprayed onto the surface of the molten steel from the top of the ladle, and oxygen-containing gas is sprayed into the molten steel from the bottom of the ladle. The spraying time of the decarburization agent and the oxygen-containing gas is 10 min. The decarburization agent is fly ash, the content of SiO2 in the fly ash is not less than 50%, and the content of Fe2O3 is not less than 20%. The amount of the decarburization agent is 30 kg / (t·min). The decarburization agent is sprayed with the aid of oxygen-containing gas, and the spraying pressure of the oxygen-containing gas is 10 MPa.

[0059] 4) After the oxygen-containing gas spraying is completed, the molten steel with a temperature of 1500-1650℃ is tapped with slag blocking, and then poured into a fixed mold to cool and solidify to form a casting blank, thereby obtaining a silicon-chromium alloy. During the pouring process, the molten steel is sprayed with oxygen-containing gas at the outlet of the ladle.

[0060] The oxygen-containing gas used in the above decarburization and pouring processes has the same composition, and the oxygen-containing gas is a mixture of pure oxygen and air, wherein the volume fraction of pure oxygen is 40%. The oxygen-containing gas supply intensity is 0.2 m 3 / (t·min) in terms of pure oxygen. Example 4

[0061] A process for smelting a silicon-chromium alloy by using an oxygen-enriched top and bottom blowing method, comprising the following steps:

[0062] 1) The silica, coke and high-carbon chromium iron are weighed by weight parts, and after being crushed respectively, the above production materials are mixed uniformly. The weight part of the silica is 305 parts, and the particle size is 50-150 mm, wherein the content of SiO2 is ≥98%. The weight part of the coke is 165 parts, and the particle size is 20-45 mm, wherein the content of carbon is ≥85%. The weight part of the high-carbon chromium iron is 110 parts, and the particle size is 20-100 mm, wherein the content of chromium is >65%.

[0063] 2) The mixed production materials are sent into the electric furnace to form molten steel by electric smelting. The secondary working voltage of the electric furnace is 273 V, the secondary working current is 8000 A, and the smelting time is 4 h. The electric furnace adopts three electrodes, and the diameter of the pole core circle formed by the three electrodes is 1.22d, d being the electrode diameter.

[0064] 3) Pour the molten steel in the ladle, spray the decarburization agent on the surface of the molten steel in the ladle, and spray the oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time of the decarburization agent and the oxygen-containing gas is 12 min. The decarburization agent is fly ash, the content of SiO2 in the fly ash is not less than 50%, and the content of Fe2O3 is not less than 20%. The amount of the decarburization agent is 33 kg / (t·min). The decarburization agent is sprayed with the aid of oxygen-containing gas, and the spraying pressure of the oxygen-containing gas is 10 MPa.

[0065] 4) After the oxygen-containing gas spraying is completed, the molten steel with a temperature of 1500-1650℃ is discharged with slag blocking, poured into a fixed mold, and cooled and solidified to form a casting blank, thereby obtaining a silicon-chromium alloy. During the pouring process, the molten steel is sprayed with oxygen-containing gas at the water outlet of the ladle.

[0066] The oxygen-containing gas used in the above decarburization and pouring processes has the same composition, and the oxygen-containing gas is a mixed gas of pure oxygen and air, wherein the volume ratio of pure oxygen is 50%. The oxygen-containing gas supply intensity is 0.3 m 3 / (t·min) in terms of pure oxygen.

[0067] Comparative Example 1

[0068] A process for smelting a silicon-chromium alloy by using a top and bottom double-blowing method with oxygen enrichment, which is different from Example 4 only in the following steps:

[0069] 3) Pour the molten steel in the ladle, spray the oxygen-containing gas on the surface of the molten steel in the ladle, and spray the oxygen-containing gas into the molten steel from the bottom of the ladle. The spraying time of the oxygen-containing gas at the top and bottom is 12 min. The spraying pressure of the oxygen-containing gas at the top is 10 MPa. That is, no fly ash is sprayed on the surface of the ladle.

[0070] Comparative Example 2

[0071] A process for smelting a silicon-chromium alloy by using a top and bottom double-blowing method with oxygen enrichment, which is different from Example 4 only in the following steps:

[0072] 3) Pour the molten steel in the ladle, and after the temperature is reduced to 1500-1650℃, discharge the molten steel with slag blocking, pour into a fixed mold, and cool and solidify to form a casting blank, thereby obtaining a silicon-chromium alloy. That is, the molten steel is not sprayed with a decarburization agent and oxygen-containing gas.

[0073] Take the finished silicon-chromium alloy produced in the examples and comparative examples, and detect the mass fraction of the chemical components by the method in GB / T 4009-2008 "Silicon-chromium Alloy". Each test sample has 3 parallel samples, and the average value is taken. The results are shown in Table 1.

[0074] Table 1 (unit: %)

[0075]

[0076] From the data of the above table, in the smelting method of the present application, due to the reason of the injection of fly ash, the silicon content in the finished alloy can be increased from more than 40% of the ordinary alloy to more than 50%, the carbon content can be further reduced to less than 0.03%, and the reduction of other impurity contents also has a slight effect, and the grade and quality of the finished alloy are significantly improved. In Comparative Example 1, since fly ash is not injected, the silicon content in the finished alloy is significantly reduced, and the carbon content is slightly increased, but the quality is acceptable, which can be classified into FeCr30Si40-C grade. In Comparative Example 2, since neither fly ash nor oxygen-containing gas is injected, the silicon content is reduced, and the carbon content is significantly increased, which is classified into FeCr30Si40-D grade, and the quality is obviously inferior to that of the finished alloy of each example. It can be seen that the injection of fly ash has a significant gain effect on decarburization and silicon increase and alloy quality improvement, and provides a new utilization way for fly ash.

[0077] It should be noted that in the present application, the detailed steps of some operations are not described in detail, but are known to those skilled in the art as prior art, and therefore will not be described here. In addition, in the present application, all features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are only for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0078] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto. In the present application, all possible combinations of the technical features in each embodiment or example are not described, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope disclosed in the present specification. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that; the technical solutions described in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements 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 application.

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 according to their weight parts, and after pulverizing them separately, mix the above raw materials evenly; the silica has a weight part of 290-310 parts, a particle size of 50-150mm, and a SiO2 content ≥98%; the coke has a weight part of 160-170 parts, a particle size of 20-45mm, and a carbon content ≥85%; the high-carbon ferrochrome has a weight part of 105-110 parts, a particle size of 20-100mm, and a chromium content >65%; 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 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.

3. The process for smelting silicon-chromium alloy using the oxygen-enriched top-bottom double-blowing method according to claim 2, 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.

4. The process for smelting silicon-chromium alloy using the oxygen-enriched top-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.

5. The process for smelting silicon-chromium alloys using the oxygen-enriched top-and-bottom double-blowing method according to claim 4, characterized in that, The oxygen-containing components used in the decarburization and casting processes are the same, consisting of a mixture of pure oxygen and air, with pure oxygen accounting for 30-50% of the volume.

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 supply intensity, measured using a pure oxygen meter, is 0.2-0.3 m³ / s. 3 / (t·min).

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