A method for producing rare earth silicon alloy based on rare earth slag

Abstract

The present application relates to the technical field of rare earth silicon alloy, and particularly relates to a rare earth silicon alloy production method based on rare earth slag, which comprises the following steps: crushing and grinding the rare earth slag and ferrosilicon respectively to obtain rare earth slag raw material and ferrosilicon powder; mixing the rare earth slag raw material and lime to obtain mixed furnace charge; obtaining the furnace bottom image of an electric arc furnace for high-temperature melting of the mixed furnace charge, and obtaining the to-be-reduced slag phase furnace charge; spraying the to-be-reduced slag phase furnace charge with mixed gas of compressed air and ferrosilicon powder through a spray gun, and continuously spraying the to-be-reduced slag phase furnace charge with the mixed gas according to the spray flow of the spray gun and the angle of the spray gun, so as to obtain a mixture of rare earth silicon alloy melt and silicate slag; and sequentially performing standing, separation and cooling forming on the mixture, so as to obtain a rare earth ferrosilicon alloy product. The present application realizes the improvement of the product quality of the produced rare earth silicon alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth silicon alloys, and particularly relates to a production method of rare earth silicon alloys based on rare earth slag. Background Art

[0002] Rare earth ferrosilicon is a type of master alloy, which is widely used in steel smelting, casting and magnetic material fields. As an additive, it can improve the mechanical properties and physical characteristics of materials. At present, the main production methods of rare earth ferrosilicon include two types: silicothermic reduction method and carbothermic reduction method. The silicothermic reduction method uses rare earth concentrate or rare earth enriched slag as raw material, 75% ferrosilicon as reducing agent, and lime as flux, to carry out smelting in an electric arc furnace. This method adopts electric arc furnace smelting equipment, and has the characteristics of simple operation, easy control of furnace conditions, flexible production, convenient startup and shutdown, and high yield. However, the existing silicothermic reduction method for producing rare earth ferrosilicon still has the following problems: during the electric arc furnace smelting process, the furnace lining is subjected to high-temperature radiation of arc light as well as scouring of molten slag and molten iron. With the increase of smelting batches, the furnace bottom and furnace slope areas will be eroded to varying degrees, forming depressions or pits. The change of the bottom morphology of the molten slag phase charge caused by erosion further affects the injection reduction process. Moreover, during the whole smelting process, the fan often runs at full speed close to the rated speed, or only maintains high-load operation in the oxidation period with the maximum flue gas volume. Taking the fourth hole exhaust in the furnace as an example, its exhaust volume is usually 800 per ton of steel / h; while the exhaust volume of the roof hood is about 9000 per ton of steel / h. Most of the existing exhaust control adopts a one-way control logic that the higher the concentration, the higher the speed. After the fan is started, it runs at full speed or high speed according to the preset air volume, and lacks a low-speed protection mechanism for local abnormal working conditions. Therefore, it is urgent to develop a production method of rare earth silicon alloys based on rare earth slag.

[0003] Chinese Patent Application Publication No. CN119571010A discloses a powder injection refining process for the production of rare earth oxide dispersion strengthened alloys. During tapping of the converter, 4.5 to 8.5 kg / t of ferrosilicon aluminum is used for strong deoxidation; after tapping, 0.2 to 0.4 kg / t of rare earth aluminum alloy is added to the slag surface of the ladle for slag surface deoxidation; the molten steel is transported to the powder injection station, the temperature of the molten steel is adjusted to 1570 to 1610°C, and the rare earth blowing agent is injected into the molten steel at high speed using an inert carrier gas. The working pressure of the carrier gas for ladle powder injection delivery is 3.0-4.0 bar, the carrier gas flow rate is 40-60 m3 / h, the ladle powder injection speed is 10-50 kg / min, and the amount of the blowing agent is 1.0 to 50.0 kg / t. After adopting this powder injection refining process, the solid solution oxygen content in the steel can be increased to more than 100 ppm, and the solid solution content of RE elements can be increased to more than 300 ppm, so as to form a nano rare earth oxide dispersion strengthened alloy.

[0004] Therefore, the powder spraying refining process used for the production of rare earth oxide dispersion strengthened alloys has the following problems: the substrate of the electric arc furnace is eroded by molten slag and molten iron, resulting in depressions or pits, which in turn leads to changes in the shape of the bottom of the molten slag phase furnace charge. This causes the reduction reaction efficiency to decrease due to the increased raw material density and poor fluidity inside the pits. Furthermore, the incomplete reduction reaction of raw materials in the pit area leads to abnormal local real-time flue gas concentration, resulting in a decrease in the accuracy of the start-up timing of the exhaust fan. Summary of the Invention

[0005] To address these issues, the present invention provides a method for producing rare earth silicon alloys based on rare earth slag, which overcomes the problems in the prior art where the substrate of the electric arc furnace is eroded by molten slag and iron, resulting in depressions or pits, which in turn cause changes in the shape of the bottom of the molten slag phase furnace charge. This leads to a decrease in the reduction reaction efficiency due to increased raw material density and reduced fluidity inside the pits, and an incomplete reduction reaction of raw materials in the pit area, resulting in abnormal local real-time flue gas concentration and a decrease in the accuracy of the start-up timing of the exhaust fan.

[0006] To achieve the above objectives, the present invention provides a method for producing rare earth silicon alloys based on rare earth slag, comprising: Rare earth slag and ferrosilicon are crushed and ground separately to obtain rare earth slag raw material and ferrosilicon powder. The rare earth slag raw material and lime are mixed to obtain a mixed furnace charge; After obtaining the furnace bottom image of the electric arc furnace that performs high-temperature melting of the mixed furnace charge, the mixed furnace charge is melted at high temperature to obtain the slag phase furnace charge to be reduced; A mixture of compressed air and ferrosilicon powder is injected into the slag-phase charge to be reduced using a spray gun. The spray flow rate and angle of the spray gun are determined based on the abnormal state of the molten slag-phase charge inside the electric arc furnace. The abnormal states of the molten slag phase furnace charge include shallow erosion abnormal state and pit erosion abnormal state. The initial exhaust velocity of the blower for exhausting flue gas in the electric arc furnace is determined based on the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase furnace charge, which is determined to be in an abnormal state of pit erosion. The mixed gas is continued to be injected into the furnace charge to be reduced according to the injection flow rate and the angle of the injection gun, and the electric arc furnace is vented according to the initial exhaust speed of the blower during the injection process to obtain a mixture of rare earth silicon alloy melt and silicate slag. The mixture is subjected to a series of processes including settling, separation, and cooling to form a rare earth ferrosilicon alloy product.

[0007] Furthermore, the erosion area is the largest furnace bottom area in the furnace bottom image of the electric arc furnace corresponding to pixels with gray values ​​less than the critical gray value threshold.

[0008] Furthermore, if the vertical projected area of ​​the erosion region is greater than the second critical area, and the erosion thickness is less than the first critical thickness, then the abnormal state of the molten slag phase furnace material inside the electric arc furnace is determined to be a shallow erosion abnormal state.

[0009] Furthermore, if the vertical projected area of ​​the erosion region is less than the first critical area, and the erosion thickness is greater than the second critical thickness, then the abnormal state of the molten slag phase furnace charge inside the electric arc furnace is determined to be an abnormal state of pit erosion.

[0010] Furthermore, based on the fact that the abnormal state of the molten slag phase furnace charge inside the electric arc furnace is a shallow erosion abnormal state, the injection flow rate of the spray gun is increased.

[0011] Furthermore, based on the abnormal state of the molten slag phase furnace charge inside the electric arc furnace being a pit erosion abnormal state, the angle of the spray gun is adjusted to face the center of the erosion area.

[0012] Furthermore, the determination of the initial exhaust velocity of the blower for exhausting flue gas from the electric arc furnace based on the real-time flue gas concentration at the detection point above the molten slag phase charge, which is determined to be in an abnormal state of pit erosion, includes: Obtain the real-time flue gas concentration at the detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion. The real-time flue gas concentration is compared with the critical flue gas concentration; Based on the comparison results of the real-time flue gas concentration being greater than the critical flue gas concentration, it was determined that the impact of the erosion area at the bottom of the electric arc furnace on the accuracy of the start-up timing of the exhaust fan did not meet the requirements, and the initial exhaust gas extraction speed of the exhaust fan was reduced.

[0013] Furthermore, the initial exhaust gas extraction rate is negatively correlated with the real-time flue gas concentration at the detection point above the molten slag phase furnace charge in the pit erosion abnormal state.

[0014] Furthermore, based on the fact that the reduction in the real-time flue gas concentration is greater than the baseline reduction, and that the carbon monoxide concentration in the flue gas during the exhaust process of the exhaust fan reaches the critical carbon monoxide concentration, it is determined that the ferrosilicon powder has reached the pit inside the erosion area, making the temperature value of the slag phase furnace material to be reduced meet the requirements, and the exhaust speed is determined as the standard exhaust speed.

[0015] Furthermore, the decrease in real-time flue gas concentration is the difference between the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion and the critical flue gas concentration.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention obtains an image of the furnace bottom of the electric arc furnace, showing depressions or pits caused by slag and molten iron erosion on the furnace substrate. Based on the vertical projection area and thickness of the eroded area, the type of eroded area is determined. When the eroded area is a large-area shallow depression, the raw material tends to accumulate at the edge of the large-area depression under gravity. The thickness of the raw material layer at the accumulation point increases, which in turn causes the arc heat and the hot melt of the upper part of the molten slag phase charge to need to penetrate a thicker layer to reach the bottom of the accumulation area, resulting in delayed heating of the bottom charge. As the liquid phase ratio decreases, the electrical and thermal conductivity of the accumulation area is lower than that of the surrounding furnace charge, resulting in a decrease in the stirring efficiency of the electromagnetic stirring force in the accumulation area. This further weakens the horizontal convection driving force of the furnace charge on both sides of the edge of the erosion area. At this time, by increasing the blowing flow rate of the spray gun, the stirring intensity of the mixed gas on the molten slag phase furnace charge is enhanced. The impact and agitation of the airflow promote the re-participation of the raw materials in the accumulation area into the convection circulation of the molten slag phase furnace charge. In addition, the increased gas flow rate carries more ferrosilicon powder into the molten slag phase furnace charge, which makes up for the problem of uneven distribution of reducing agent caused by the decrease in flowability. When the eroded area presents as a small, deep pit, the electromagnetic stirring at the edge of the pit reduces the flow capacity of the convection, hindering the heat convection exchange between the furnace charge inside and outside the pit. This makes it difficult for external heat to enter, increasing the temperature difference between the inside and outside of the pit. In this case, by adjusting the angle of the spray gun to deflect towards the center of the eroded area, the jet can directly impact the inside of the pit. The kinetic energy of the jet increases the movement of the furnace charge inside the pit, further improving the heat exchange effect between the inside and outside of the pit and enhancing the uniformity of the mixed furnace charge inside the electric arc furnace.

[0017] Furthermore, this invention addresses the issue of small-area deep pits in the eroded area of ​​the furnace bottom when the eroded area is reduced by lowering the initial exhaust gas extraction speed of the exhaust fan. Due to the depth of the pits, the mixed gas ejected from the spray gun encounters the inclined slope at the edge of the pit. When the compressed air and ferrosilicon powder mixture ejected from the spray gun is sprayed towards the pit, it is blocked and deflected by the slope. The deflected compressed air carries some ferrosilicon powder to form a local high-concentration airflow in the area above the pit, causing the real-time flue gas concentration detected by the flue gas concentration sensor above the pit to increase. Specifically, if the exhaust fan is turned on based on the increased real-time flue gas concentration, the exhaust fan will draw away the mixed gas of compressed air and ferrosilicon powder sprayed by the spray gun. The airflow that is drawn away carries away some of the spray kinetic energy, resulting in a weakening of the jet impact force that actually reaches the molten slag phase furnace charge. In addition, the ferrosilicon powder is lost with the flue gas, reducing the amount of reducing agent that actually enters the molten slag phase furnace charge. This reduces the mixing and reduction effects of the mixed gas. Therefore, by reducing the initial exhaust speed of the exhaust fan when there is an erosion area with a pit shape at the bottom of the furnace, and the real-time flue gas concentration above the pit is higher than the flue gas concentration under historical conditions, the excessive exhaust fan can further prevent the loss of reducing agent and weakening of mixing due to excessive exhaust, thereby improving the reduction effect and purity of the rare earth silicon alloy melt. Attached Figure Description

[0018] Figure 1 This is an overall flow chart of the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the rare earth silicon alloy production equipment in the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention. Figure 3 This is a logic block diagram of the spray flow rate and the angle of the spray gun in the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention. Figure 4 This is a logic block diagram of the method for producing rare earth silicon alloy based on rare earth slag according to an embodiment of the present invention, which determines the initial exhaust velocity of the fan.

[0019] Explanation of reference numerals in the attached drawings: 1-Electric arc furnace, 2-Electrode, 3-Spray gun, 4-Storage tank, 5-Pressure gauge, 6-Fume hood, 7-First exhaust pipe, 8-Second exhaust pipe, 9-Fume gas concentration sensor, 10-Cooling tank, 11-First fan, 12-Second fan, 13-Dust collector. Detailed Implementation

[0020] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0021] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0023] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Please see Figure 1 The diagram shown is an overall flow chart of the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention; the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention includes: Step S1: The rare earth slag and ferrosilicon are crushed and ground separately to obtain rare earth slag raw material and ferrosilicon powder. Step S2: Mix the rare earth slag raw material and lime to obtain a mixed furnace charge; Step S3: After obtaining the bottom image of the electric arc furnace for high-temperature melting of the mixed furnace charge, the mixed furnace charge is melted at high temperature to obtain the slag phase furnace charge to be reduced. Step S4: A mixture of compressed air and ferrosilicon powder is injected into the slag phase charge to be reduced using a spray gun. The spray flow rate and angle of the spray gun are determined based on the abnormal state of the molten slag phase charge inside the electric arc furnace. The abnormal states of the molten slag phase furnace charge include shallow erosion abnormal state and pit erosion abnormal state. Step S5: Determine the initial exhaust speed of the blower for exhausting smoke from the electric arc furnace based on the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion. Step S6: Continue to spray the mixed gas into the furnace charge to be reduced according to the spray flow rate and the angle of the spray gun, and exhaust the electric arc furnace according to the initial exhaust speed of the blower during the spraying process to obtain a mixture of rare earth silicon alloy melt and silicate slag. Step S7: The mixture is subjected to static standing, separation, and cooling molding in sequence to obtain a rare earth ferrosilicon alloy product.

[0025] Please see Figure 2The diagram shows a structural schematic of the rare earth silicon alloy production equipment in an embodiment of the present invention, which is based on a rare earth slag method for producing rare earth silicon alloys. The rare earth alloy production equipment includes: Electric arc furnace 1, which provides reaction space for the slag phase charge to be reduced; Electrode 2, part of which is located inside the electric arc furnace, is used to provide arc heat to the slag phase charge to be reduced; The flue gas concentration sensor 9 is installed at the top of the electric arc furnace to obtain the real-time flue gas concentration above the molten slag phase furnace charge. Specifically, the flue gas concentration sensor draws flue gas from the top of the furnace cover through a sampling tube for detection to avoid the sensor being directly exposed to the high-temperature furnace gas. Fume hood 6 is installed above the electric arc furnace to limit the amount of flue gas diffused outside the electric arc furnace; The first exhaust pipe 7, connected to the fume hood, is used to limit the diffusion path of the smoke. The first exhaust pipe is equipped with a carbon monoxide concentration sensor to obtain the carbon monoxide concentration in the flue gas in real time. The second exhaust pipe 8 is connected to the electric arc furnace and is used to limit the diffusion path of the flue gas inside the electric arc furnace. Cooling tank 10 is connected to the second exhaust pipe and is used to cool and reduce the temperature of the flue gas; The first fan 11 is connected to the cooling tank and is used to provide suction power for the exhaust of flue gas inside the electric arc furnace. The second fan 12 is connected to the first exhaust pipe and is used to provide suction power for the exhaust of the smoke collected in the fume hood. Dust collector 13, which is connected to the second fan, is used to collect and store dust particles in the flue gas; The spray gun 3 is set on the side wall of the electric arc furnace and is used to spray a mixture of compressed air and ferrosilicon powder into the electric arc furnace. The jet flow rate regulating valve is connected to the spray gun and is used to limit the jet flow rate of the spray gun; An angle adapter, which is installed on the spray gun, is used to limit the spray angle of the spray gun; Storage tank 4, which is connected to the spray gun, is used to store a mixture of compressed air and ferrosilicon powder; Pressure gauge 5 is connected to the storage tank to obtain the gas pressure inside the storage tank in real time.

[0026] In this embodiment, the working process of the rare earth alloy production equipment is as follows: before the mixed furnace charge is fed into the electric arc furnace, an industrial endoscope is inserted into the furnace through a pre-reserved detection hole on the top of the furnace to obtain an image of the furnace bottom. Image processing technology is used to identify the vertical projection area and erosion thickness of the eroded area on the furnace bottom. Subsequently, the crushed and ground rare earth slag raw material is mixed with lime in a certain proportion and fed into the electric arc furnace 1. Electrode 2 is energized to generate a high-temperature electric arc, heating the mixed furnace charge to 1100℃~1200℃ for high-temperature melting, obtaining the slag phase furnace charge to be reduced. During the high-temperature melting process and the subsequent blowing reduction process, the fume hood 6 covers the electric arc furnace 1 to collect the slag from the furnace door, electrode holes, etc. The flue gas that escapes through the gaps is guided to the second fan 12 through the first exhaust pipe 7. After being sucked by the second fan 12, it is sent to the dust collector 13 for dust removal. The purified gas is then discharged into the atmosphere. The flue gas inside the electric arc furnace 1 is drawn out through the second exhaust pipe 8. It is first cooled down by the cooling tank 10, and then the first fan 11 provides suction power to discharge the cooled flue gas. After melting is completed, it enters the injection reduction stage. The corresponding controllers of the injection flow regulating valve and the angle adapter determine the abnormal state of the molten slag phase furnace material based on the vertical projection area and erosion thickness of the eroded area in the furnace bottom image, and adjust the injection flow and injection angle of the spray gun accordingly.

[0027] During the blowing process, the mixed gas of compressed air and ferrosilicon powder stored in the storage tank 4 is regulated by the blowing flow regulating valve and then injected into the molten slag phase furnace charge in the electric arc furnace 1 through the spray gun 3. The pressure gauge 5 monitors the gas pressure inside the storage tank 4 in real time. The blowing reduction process lasts for about 30 minutes, and the furnace temperature is controlled at 1400℃~1500℃ to allow the silane thermal reduction reaction between rare earth oxides and ferrosilicon powder to proceed fully, generating a mixture of rare earth silicon alloy melt and silicate slag.

[0028] In this embodiment, in step S1, the rare earth slag and ferrosilicon are crushed and ground to a particle size of less than 50 mm. In step S2, rare earth slag raw materials and lime are mixed using a mixer for 10 to 20 minutes.

[0029] In step S3, the melting temperature for high-temperature melting of the mixed furnace charge is 1100℃~1200℃.

[0030] Specifically, the abnormal states of the molten slag phase furnace charge include shallow erosion abnormal state and pit erosion abnormal state.

[0031] Specifically, the eroded area is the largest area of ​​the furnace bottom in the furnace bottom image of the electric arc furnace corresponding to the pixels with gray values ​​less than the critical gray value threshold.

[0032] In step S3, before the mixed furnace charge is fed into the electric arc furnace, an industrial endoscope is inserted into the furnace through a pre-reserved inspection hole on the top of the furnace to obtain an image of the furnace bottom of the electric arc furnace in the state of shutdown for maintenance or cold furnace. In this embodiment, the furnace bottom of the electric arc furnace is uncorroded, and its surface is relatively flat and smooth, reflecting light more evenly. However, the surface roughness, cracks, or slag covering the furnace bottom caused by erosion from molten slag and iron is reduced, resulting in a darker area in the image, i.e., pixels with lower grayscale values. Therefore, if the grayscale value in the corresponding furnace bottom image is greater than or equal to the critical grayscale threshold, the higher the integrity of the furnace bottom surface, the less erosion, and the smoother and smoother the surface. Conversely, if the grayscale value is less than the critical grayscale threshold, it means that the smaller the grayscale value, the more severe the erosion and the deeper the depression or pit.

[0033] In this embodiment, the critical grayscale threshold is the critical threshold for determining whether a pixel belongs to the eroded area. Under certain image acquisition conditions, including light intensity, camera exposure parameters, and lens focal length, the critical grayscale threshold is only related to the degree of erosion of the furnace bottom of the electric arc furnace. Those skilled in the art can adaptively adjust the critical grayscale threshold according to the grayscale distribution of the actual furnace bottom image, as long as the eroded area of ​​the furnace bottom can be distinguished.

[0034] In this embodiment, the erosion thickness of the erosion area is obtained by scanning the bottom of the electric arc furnace in a state of shutdown, maintenance, or cold furnace using a laser probe; the vertical projected area of ​​the erosion area is obtained by counting the total number of pixels representing the erosion area and converting this number of pixels into the actual physical area according to the actual physical size corresponding to each pixel.

[0035] Specifically, the laser probe uses the original design elevation of the furnace bottom at the beginning of production as the reference surface. During shutdown maintenance or cold furnace operation, the surface of the furnace bottom is scanned to calculate the amount of subsidence of each measuring point relative to the reference surface. This amount is used as the erosion thickness of the measuring point, and the maximum value of the erosion thickness of each measuring point is taken as the erosion thickness of the erosion area. It should be noted that the erosion area refers to the area where the furnace lining of the electric arc furnace under normal smelting conditions has not yet reached the point where it needs to be shut down for repair or replacement. When the erosion thickness exceeds 35% of the total thickness of the furnace lining, it exceeds the compensation capacity of the process adjustment of this invention. At this time, the furnace lining should be repaired or the furnace should be shut down for replacement to ensure smelting safety.

[0036] Please see Figure 3 As shown, it is a logic block diagram of the spray flow rate and the angle of the spray gun in the rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention. If the vertical projection area of ​​the erosion area is greater than the second critical area and the erosion thickness is less than the first critical thickness, then the abnormal state of the molten slag phase furnace material inside the electric arc furnace is determined to be a shallow erosion abnormal state.

[0037] In this embodiment, during conventional smelting, the furnace lining of the electric arc furnace is eroded by molten slag and iron. The vertical projected area of ​​the eroded region of the electric arc furnace lining is larger than the second critical area. The larger the area of ​​the furnace bottom covered by the eroded region, the larger the accumulation range of the slag phase charge at the edge of the recessed eroded region, and the greater the continuity and thickness of the accumulation layer. The erosion thickness of the eroded region is less than the first critical thickness. The more the recessed shape is close to a shallow dish shape, the smaller the depth variation of the furnace bottom. The molten slag phase charge tends to migrate towards the center of the recess and form a ring-shaped accumulation at the edge of the recess. When the eroded region has a large area of ​​shallow recessed shape, the slag phase charge tends to move towards the center of the recess under the action of gravity. The accumulation at the edge of the concave area increases the thickness of the furnace charge layer at the accumulation point. This causes the arc heat and the hot melt at the top of the molten pool to have to penetrate a thicker layer to reach the bottom of the accumulation area. As a result, the bottom charge heats up later and the liquid phase ratio decreases. The reduced liquid phase ratio makes the electrical and thermal conductivity of the accumulation area lower than that of the surrounding charge. This leads to a decrease in the coupling efficiency of the electromagnetic stirring force in the accumulation area, weakening the horizontal convection driving force and mass exchange efficiency between the slag phase charge on both sides of the accumulation layer. Therefore, the molten pool state corresponding to the vertical projection area of ​​the furnace bottom erosion area being greater than the second critical area and the erosion thickness being less than the first critical thickness is judged as a shallow erosion abnormal state.

[0038] Please continue reading. Figure 3 As shown, if the vertical projection area of ​​the erosion region is less than the first critical area, and the erosion thickness is greater than the second critical thickness, then the abnormal state of the molten slag phase furnace material inside the electric arc furnace is determined to be an abnormal state of pit erosion.

[0039] In this embodiment, the vertical projected area of ​​the eroded region of the electric arc furnace substrate is smaller than the first critical area. At this point, the eroded region is shaped like a pit. The narrower the opening of the pit, the smaller the material and heat exchange channel between the pit's interior and the external furnace charge. The erosion thickness of the eroded region is greater than the second critical thickness. The deeper the pit, the more inclined the slope of the pit's edge, and the stronger the physical blocking effect on the molten pool's convection circulation. When the eroded region is a small-area, deep pit, the inclined surface formed at the pit's edge disrupts the normal electromagnetic stirring and convection path of the furnace charge, leading to... The electromagnetic stirring-driven convective circulation experiences flow separation and deflection at the slope, hindering the heat convection exchange between the slag-phase charge inside and outside the pit. In other words, the high-temperature melt outside is difficult to enter the pit, and the charge that has already participated in the reaction inside the pit is also difficult to diffuse outward, resulting in an increase in the temperature difference between the inside and outside of the pit. The inside of the pit becomes a thermodynamic isolation zone, and the heat transfer efficiency decreases. Therefore, the state of the molten pool corresponding to the vertical projection area of ​​the furnace bottom erosion area being smaller than the first critical area and the erosion thickness being greater than the second critical thickness is judged as the abnormal state of pit erosion.

[0040] In this embodiment, the first critical area and the second critical area are determined based on the total area of ​​the furnace bottom of the electric arc furnace: the first critical area is 5% to 10% of the total furnace bottom area, and the second critical area is 20% to 30% of the total furnace bottom area. The first critical thickness and the second critical thickness are determined based on the total thickness of the furnace lining refractory material: the first critical thickness is 15% to 25% of the total furnace lining thickness, and the second critical thickness is 25% to 35% of the total furnace lining thickness. It should be noted that when the erosion thickness exceeds 35% of the total furnace lining thickness, it is beyond the scope of application of the process adjustment of this invention. At this time, furnace lining repair or furnace shutdown and replacement should be carried out to ensure smelting safety.

[0041] Please continue reading. Figure 3 As shown, based on the abnormal state of the molten slag phase furnace charge inside the electric arc furnace being a shallow erosion abnormal state, the spray flow rate of the spray gun is increased.

[0042] In step S4, the furnace temperature of the electric arc furnace when the mixed gas of compressed air and ferrosilicon powder is sprayed onto the slag phase material to be reduced by the spray gun is 1400℃~1500℃, so as to provide thermodynamic temperature conditions for the silane thermal reduction reaction between rare earth oxides and ferrosilicon powder in the rare earth slag raw material.

[0043] In this embodiment, to ensure that the injected mixed gas enhances stirring while avoiding excessive injection that could cause carrier gas to escape and reduce the effective amount of powder entering the molten pool, the injection flow rate of the spray gun must not exceed 25N. / h, the typical blowing flow rate under normal operating conditions is 12N. / h~20N / h. If the spray gun's blowing flow rate exceeds 25N. / h, excessive airflow impact will cause a large amount of carrier gas to escape from the surface of the molten pool, reducing the effective powder dosage actually entering the molten pool. The adjustment step size of the injection flow rate is positively correlated with the extent to which the vertical projection area of ​​the erosion zone exceeds the second critical area and the extent to which the erosion thickness is lower than the first critical thickness; specifically, for every 10 percentage points that the vertical projection area exceeds the second critical area, the flow rate increases by 1N. / h; For every 5 percentage points below the lower limit of the first critical thickness in terms of erosion thickness, the flow rate increases by 0.5N. / h; Those skilled in the art can adaptively adjust the spray flow rate of the spray gun according to the flow state of the molten pool and the residual content of rare earth oxides. By increasing the spray flow rate of the spray gun, the stirring intensity of the mixed gas on the molten slag phase charge is enhanced. The impact and agitation of the airflow promote the re-participation of the raw materials at the accumulation point in the convective circulation of the molten slag phase charge. Furthermore, the increased gas flow rate carries more ferrosilicon powder into the molten slag phase charge, compensating for the problem of uneven distribution of reducing agent caused by the decrease in flowability.

[0044] Please continue reading. Figure 3 As shown, based on the abnormal state of the molten slag phase furnace charge inside the electric arc furnace, which is a pit erosion abnormal state, the angle of the spray gun is adjusted to face the center of the erosion area. Specifically, the direction towards the center of the erosion area is the same as the direction of the line connecting the nozzle of the spray gun to the geometric center of the erosion area on the furnace bottom plane. The angle between the axis of the spray gun and the direction of the line connecting the nozzle of the spray gun to the geometric center of the erosion area on the furnace bottom plane is calculated using the coordinates of the geometric center of the erosion area in the furnace bottom image and the spatial coordinates of the nozzle of the spray gun.

[0045] In this embodiment, the initial installation direction of the spray gun is taken as 0° reference. The positive direction is the direction of deflection toward the geometric center of the erosion area, and the negative direction is the direction of deflection away from the geometric center of the erosion area. When the spray gun angle deflects more than 15° away from the center of the erosion area with the pit shape, the spray jet will directly impact the side furnace lining of the electric arc furnace. As verified by engineering practice, the jet scouring the furnace wall will cause the furnace lining refractory material to be damaged more quickly under the continuous impact and chemical erosion of the high temperature jet, shortening the service life of the furnace lining. In addition, the refractory material particles washed off enter the molten pool, contaminating the rare earth silicon alloy melt and affecting the purity of the alloy. When the spray gun angle deflects more than 15° towards the center of the pit-shaped erosion area, the path length of the sprayed jet increases. The jet must pass through a thicker slag layer before reaching the bottom of the pit, resulting in a decrease in the kinetic energy of the sprayed mixed gas. Engineering practice has verified that when the angle deflection exceeds 15°, the impact velocity of the jet upon reaching the inside of the pit is insufficient to effectively disrupt the packing structure and agitate the furnace charge inside the pit, thus reducing the spraying effect. Meanwhile, an excessively large deflection angle increases the distance between the nozzle of the spray gun and the surface of the molten pool. Some of the sprayed mixture escapes into the furnace space before entering the molten pool and is carried away by the exhaust system. Therefore, the adjustment range of the spray gun angle is [-15°, +15°]. Within this range, those skilled in the art can adaptively adjust the spray gun angle according to the center position of the eroded area, the depth of the pit, and the steepness of the pit's slope. The adjustment step of the spray gun angle should not exceed 1° to avoid a sudden change in the jet direction and instantaneous instability of the spraying effect caused by an excessively large single angle adjustment, thereby ensuring the continuity and stability of the spraying process. By adjusting the spray gun angle to deflect towards the center of the eroded area, the sprayed jet directly impacts the inside of the pit. The kinetic energy of the jet increases the movement ability of the furnace charge inside the pit, further improving the heat exchange effect inside and outside the pit and enhancing the uniformity of the mixed furnace charge inside the electric arc furnace.

[0046] In this embodiment, the adjustment step of the spray gun angle shall not exceed 1° to overcome the problems of sudden change in jet direction caused by excessive single angle adjustment and uneven distribution of spray mixture caused by instantaneous instability of spraying effect, which in turn affects the reduction reaction efficiency. Those skilled in the art can determine the adjustment step of the spray gun angle according to the geometric characteristics of the erosion area, including the depth of the pit and the steepness of the slope, as well as the real-time flow state of the molten pool during the spraying process.

[0047] In this embodiment, if the vertical projected area of ​​the erosion region is greater than the first critical area and less than the second critical area, and the erosion thickness is greater than the first critical thickness and less than the second critical thickness, then the spray flow rate of the spray gun is increased and the angle of the spray gun is adjusted to deflect towards the center of the erosion region. The increase in the spray flow rate of the spray gun is less than the increase in the spray flow rate under the abnormal state of shallow erosion, and the deflection of the spray gun angle is less than the deflection of the angle under the abnormal state of pit erosion. Furthermore, based on the fact that the rate of increase of the vertical projected area is greater than the rate of increase of the erosion thickness, the increase in the spray flow rate of the spray gun is greater than the deflection of the spray gun angle, that is, the increase in the spray flow rate is prioritized to alleviate the expansion of the deposit layer caused by the area expansion; based on the fact that the rate of increase of the vertical projected area is less than the rate of increase of the erosion thickness, the deflection of the spray gun angle is greater than the increase in the spray flow rate of the spray gun, that is, the adjustment of the spray gun angle is prioritized to alleviate the enhanced slope blocking effect caused by the increase in depth.

[0048] In step S4, the blowing time of the mixed gas injected into the slag phase charge to be reduced is 30 minutes.

[0049] Please see Figure 4 The diagram shown is a logic block diagram for determining the initial exhaust velocity of a blower in a rare earth silicon alloy production method based on rare earth slag according to an embodiment of the present invention. The determination of the initial exhaust velocity of the blower for the electric arc furnace exhaust, based on the real-time flue gas concentration at the detection point above the molten slag phase furnace charge, which is determined to be in an abnormal state of pit erosion, includes: Obtain the real-time flue gas concentration at the detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion. The real-time flue gas concentration is compared with the critical flue gas concentration; Based on the comparison results of the real-time flue gas concentration being greater than the critical flue gas concentration, it was determined that the impact of the erosion area at the bottom of the electric arc furnace on the accuracy of the start-up timing of the exhaust fan did not meet the requirements, and the initial exhaust gas extraction speed of the exhaust fan was reduced.

[0050] Specifically, the initial exhaust gas extraction rate is negatively correlated with the real-time flue gas concentration at the detection point above the molten slag phase furnace charge in the pit erosion abnormal state.

[0051] Specifically, the real-time flue gas concentration is the concentration of dust particles in the flue gas at the top of the electric arc furnace, and the unit of real-time flue gas concentration is mg / L. The concentration is detected in real time by a flue gas concentration sensor. The increase in real-time flue gas concentration directly reflects the amount of solid particles, including ferrosilicon powder and furnace charge dust, carried away by the jet. It is a critical indicator for judging whether the jet is deflected by the slope, resulting in the loss of reducing agent.

[0052] Those skilled in the art will understand that the flue gas concentration sensor can be a light scattering dust concentration sensor, a charge induction dust concentration sensor, or a light-transmitting dust concentration monitor. It only needs to meet the requirement of real-time detection of dust particle concentration in the flue gas at the top of the electric arc furnace in a high-temperature, high-dust-concentration electric arc furnace flue gas environment. Those skilled in the art can make adaptive adjustments to the type and range of the flue gas concentration sensor according to the actual working conditions inside the electric arc furnace, which will not be elaborated here.

[0053] In this embodiment, the critical flue gas concentration is determined based on the background flue gas concentration of the electric arc furnace under normal operating conditions. The critical flue gas concentration is 5 to 8 times the background flue gas concentration. The background flue gas concentration is the stable stage of normal rare earth silicon alloy smelting without injection interference. The critical flue gas concentration is the reference value of the concentration of dust particles in the flue gas detected by the flue gas concentration sensor. The critical flue gas concentration is the upper limit threshold for determining whether the real-time flue gas concentration has reached the abnormal emission state. It is used to distinguish between normal flue gas emission and abnormal emission caused by the deflection of the injection mixture by the pit slope. Those skilled in the art can make adaptive adjustments to the critical flue gas concentration within the above range according to actual operating conditions, including rare earth slag composition, injection parameters, furnace negative pressure setting value, etc.

[0054] Specifically, based on the fact that the reduction in real-time flue gas concentration is greater than the baseline reduction, and that the carbon monoxide concentration in the flue gas during the exhaust process of the exhaust fan reaches the critical carbon monoxide concentration, it is determined that the ferrosilicon powder has reached the pit inside the erosion area, so that the temperature value of the slag phase furnace material to be reduced meets the requirements, and the extraction speed is determined as the standard extraction speed.

[0055] Specifically, the reduction in real-time flue gas concentration is the difference between the real-time flue gas concentration at the detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion and the critical flue gas concentration.

[0056] In this embodiment, when the real-time flue gas concentration is between the upper limit of the background flue gas concentration and the critical flue gas concentration, it indicates that the local airflow in the area where the detection point is located has a certain degree of dispersion but has not reached a serious abnormal state. At this time, the fan maintains the reduced pumping speed until the concentration falls back below the upper limit of the background flue gas concentration and the carbon monoxide reaches the critical carbon monoxide concentration, and then resumes the standard pumping speed.

[0057] In this embodiment, the baseline reduction is the difference between the critical flue gas concentration and the upper limit of the background flue gas concentration. The upper limit of the background flue gas concentration is determined based on the upper limit of the fluctuation range of the background flue gas concentration under normal operating conditions of the electric arc furnace, and is usually taken as 2 to 3 times the background flue gas concentration. The upper limit of the background flue gas concentration represents the highest level of normal fluctuation of flue gas concentration when no abnormal emissions occur. When the real-time flue gas concentration drops below the upper limit of the background flue gas concentration, it indicates that the emission of the injected mixture begins to decrease, that is, the reduction is greater than the baseline reduction. At this time, in conjunction with the determination that the carbon monoxide concentration meets the standard, it is confirmed that the injection has entered a stable and effective state, and the fan speed is restored to the standard extraction speed.

[0058] In this embodiment, the higher the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase charge, the greater the degree of local airflow anomaly in the area where the detection point is located, and the more deflected and dispersed the injected gas. Due to the depth of the pit, the mixed gas ejected by the spray gun hits the inclined slope at the edge of the pit. When the compressed air and ferrosilicon powder mixture ejected by the spray gun is sprayed towards the pit, it is blocked and deflected by the slope. The deflected compressed air carries some ferrosilicon powder to form a local high-concentration airflow in the area above the pit, causing the real-time flue gas concentration detected by the flue gas concentration sensor above the pit to rise. If the fan for exhaust is turned on at this time based on the real-time flue gas concentration being greater than the preset concentration, the fan will draw away the mixed gas of compressed air and ferrosilicon powder ejected by the spray gun. The airflow that is drawn away carries away some of the ejection kinetic energy, resulting in a weakening of the jet impact force that actually reaches the molten slag phase charge. In addition, the ferrosilicon powder is lost with the flue gas, and the actual amount of reducing agent entering the molten slag phase charge is reduced, resulting in a decrease in the mixing effect and reduction effect of the mixed gas.

[0059] In this embodiment, the initial exhaust speed of the exhaust fan is adjusted by the first fan.

[0060] In this embodiment, to ensure that the exhaust fan can avoid excessive air extraction and carry away the injected mixture under abnormal pit conditions, the initial exhaust speed of the exhaust fan must not be lower than the minimum effective speed determined by the minimum exhaust capacity required to maintain the slight negative pressure state of the furnace. If the initial exhaust speed of the exhaust fan is lower than this minimum effective speed, the negative pressure above the furnace will not be sufficient to effectively capture the escaped flue gas. High-temperature dusty flue gas will escape from parts such as the furnace door, electrode holes, and furnace cover gaps because the furnace pressure is higher than the external atmospheric pressure. Those skilled in the art can adaptively adjust the initial exhaust speed of the exhaust fan according to the degree of deviation of the concentration of flue gas at the detection point above the pit from the normal value, as well as the pit depth and slope steepness of the pit erosion area. By reducing the initial exhaust speed of the exhaust fan, the loss of reducing agent and weakened stirring caused by excessive air extraction by the fan can be further prevented, thereby improving the reduction effect and purity of the rare earth silicon alloy melt.

[0061] In this embodiment, the reduction in the extraction speed is positively correlated with the degree to which the real-time flue gas concentration exceeds the critical flue gas concentration. Specifically, the extraction speed is reduced by 5% for every 10% increase in the real-time flue gas concentration beyond the critical concentration. However, the reduced extraction speed must not be lower than the minimum effective speed required to maintain the slight negative pressure state in the furnace. The minimum effective speed is usually 40% to 50% of the standard extraction speed. When the real-time flue gas concentration falls back below the critical concentration, the extraction speed is gradually restored to the standard extraction speed. The step size of the restoration is determined based on the rate of decrease of the real-time flue gas concentration.

[0062] In one specific embodiment, the standard exhaust velocity of the first fan for exhausting flue gas from the electric arc furnace is 657 r / min.

[0063] Understandably, when the real-time flue gas concentration fluctuates little during the injection process, the adjustment step size of the extraction speed is usually 3% to 5% of the standard extraction speed. Similarly, when the initial stage of the injection process or when the real-time flue gas concentration fluctuates greatly, the adjustment step size of the extraction speed is usually 1% to 2% of the standard extraction speed. Therefore, those skilled in the art can adaptively adjust the recovery step size and the reduction step size of the extraction speed according to the real-time flue gas concentration above the pit and its changing trend.

[0064] Understandably, in the high-temperature environment of an electric arc furnace, graphite electrodes and carbon furnace linings participate in the carbothermic reduction reaction. The presence of carbon monoxide directly proves that a high-temperature reduction reaction has occurred inside the furnace, and the reaction temperature has reached the level required for carbon to participate in the reduction. The higher the concentration of carbon monoxide in the flue gas during the exhaust process, the faster the reduction reaction rate between ferrosilicon powder and rare earth oxides inside the pit. The reduced slag phase furnace charge has reached and maintained the temperature range required for the reduction reaction. At the same time, it indicates that the injected mixed gas can continuously and effectively enter the pit and participate in the reaction, rather than continuing to be blocked by the slope and escape. Therefore, when the reduction reaction inside the pit is fully started, the amount of carbon monoxide produced in the furnace continues to increase, and it is necessary to restore the standard exhaust speed to prevent the flue gas from accumulating and overflowing.

[0065] In this embodiment, step S7 includes: Step S71: Pour the mixture of rare earth silicon alloy melt and silicate slag into a slag iron pot and let it stand in the slag iron pot for 8 hours. The density difference between the rare earth silicon alloy melt and the silicate slag will cause the rare earth silicon alloy melt to sink to the bottom of the slag iron pot and the silicate slag to float on the top layer of the slag iron pot. Step S72: The layered rare earth silicon alloy melt is discharged through the tapping port of the slag iron ladle, and the rare earth silicon alloy melt is cooled and shaped to obtain a rare earth silicon iron alloy product. Specifically, the rare earth silicon alloy melt is poured from the tapping port at the bottom of the slag iron ladle into the ingot mold, and water-cooled ingot mold is used for forced cooling. After cooling, the rare earth silicon iron alloy product is obtained by demolding. Step S73: The stratified silicate slag is discharged through the slag outlet and subjected to water quenching treatment. Specifically, the upper layer of silicate slag is poured out from the slag outlet at the top of the slag-iron ladle. The molten slag is transported to the side of the water pool and slowly poured into the tundish using the pre-furnace water quenching method. The molten slag is crushed by pressurized water and cooled into granules to complete the water quenching treatment. After water quenching, granulated slag with amorphous glass as the main component is obtained, wherein the glass content of the granulated slag is 93% to 95%. The slag after water quenching treatment can be further used in building materials.

[0066] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for producing rare earth silicon alloys based on rare earth slag, characterized in that, include: Rare earth slag and ferrosilicon are crushed and ground separately to obtain rare earth slag raw material and ferrosilicon powder. The rare earth slag raw material and lime are mixed to obtain a mixed furnace charge; After obtaining the furnace bottom image of the electric arc furnace that performs high-temperature melting of the mixed furnace charge, the mixed furnace charge is melted at high temperature to obtain the slag phase furnace charge to be reduced; A mixture of compressed air and ferrosilicon powder is injected into the slag-phase charge to be reduced using a spray gun. The spray flow rate and angle of the spray gun are determined based on the abnormal state of the molten slag-phase charge inside the electric arc furnace. The abnormal states of the molten slag phase furnace charge include shallow erosion abnormal state and pit erosion abnormal state. The initial exhaust velocity of the blower for exhausting flue gas in the electric arc furnace is determined based on the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase furnace charge, which is determined to be in an abnormal state of pit erosion. The mixed gas is continued to be injected into the furnace charge to be reduced according to the injection flow rate and the angle of the injection gun, and the electric arc furnace is vented according to the initial exhaust speed of the blower during the injection process to obtain a mixture of rare earth silicon alloy melt and silicate slag. The mixture is subjected to a series of processes including settling, separation, and cooling to form a rare earth ferrosilicon alloy product.

2. The method for producing rare earth silicon alloys based on rare earth slag according to claim 1, characterized in that, The erosion area is the largest area of ​​the furnace bottom in the furnace bottom image of the electric arc furnace corresponding to the pixels with gray values ​​less than the critical gray value threshold.

3. The method for producing rare earth silicon alloys based on rare earth slag according to claim 2, characterized in that, If the vertical projection area of ​​the erosion zone is greater than the second critical area, and the erosion thickness is less than the first critical thickness, then the abnormal state of the molten slag phase furnace material inside the electric arc furnace is determined to be a shallow erosion abnormal state.

4. The method for producing rare earth silicon alloys based on rare earth slag according to claim 3, characterized in that, If the vertical projection area of ​​the erosion zone is less than the first critical area, and the erosion thickness is greater than the second critical thickness, then the abnormal state of the molten slag phase furnace material inside the electric arc furnace is determined to be an abnormal state of pit erosion.

5. The method for producing rare earth silicon alloys based on rare earth slag according to claim 4, characterized in that, Based on the fact that the abnormal state of the molten slag phase furnace charge inside the electric arc furnace is a shallow erosion abnormal state, the injection flow rate of the spray gun is increased.

6. The method for producing rare earth silicon alloys based on rare earth slag according to claim 5, characterized in that, Based on the abnormal state of the molten slag phase furnace charge inside the electric arc furnace, which is a pit erosion abnormal state, the angle of the spray gun is adjusted to face the center of the erosion area.

7. The method for producing rare earth silicon alloys based on rare earth slag according to claim 6, characterized in that, The determination of the initial exhaust velocity of the blower for the electric arc furnace exhaust based on the real-time flue gas concentration at the detection point above the molten slag phase furnace charge, which is determined to be in an abnormal state of pit erosion, includes: Obtain the real-time flue gas concentration at the detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion. The real-time flue gas concentration is compared with the critical flue gas concentration; Based on the comparison results of the real-time flue gas concentration being greater than the critical flue gas concentration, it was determined that the impact of the erosion area at the bottom of the electric arc furnace on the accuracy of the start-up timing of the exhaust fan did not meet the requirements, and the initial exhaust gas extraction speed of the exhaust fan was reduced.

8. The method for producing rare earth silicon alloys based on rare earth slag according to claim 7, characterized in that, The initial exhaust gas extraction rate is negatively correlated with the real-time flue gas concentration at the detection point above the molten slag phase furnace charge in the pit erosion abnormal state.

9. The method for producing rare earth silicon alloys based on rare earth slag according to claim 8, characterized in that, Based on the fact that the reduction in real-time flue gas concentration is greater than the baseline reduction, and that the carbon monoxide concentration in the flue gas during the exhaust process of the exhaust fan reaches the critical carbon monoxide concentration, it is determined that the ferrosilicon powder has reached the pit inside the erosion area, so that the temperature value of the slag phase furnace material to be reduced meets the requirements, and the extraction speed is determined as the standard extraction speed.

10. The method for producing rare earth silicon alloy based on rare earth slag according to claim 9, characterized in that, The decrease in real-time flue gas concentration is the difference between the real-time flue gas concentration at the flue gas concentration detection point above the molten slag phase furnace charge that is determined to be in an abnormal state of pit erosion and the critical flue gas concentration.

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