Method for recycling iron-silicon-aluminum alloy from scrap

Abstract

The present application relates to the technical field of metal material recycling, and discloses a method for recycling and processing iron-silicon-aluminum alloy from scrap steel, which comprises the following steps: adding multi-element synthetic refining slag to the surface of a scrap steel melt and adjusting the optical basicity; when the combined amount of iron oxide and manganese oxide in the refining slag is reduced to less than 0.5%, first adding part of silicon blocks around the feeding channel to build a low-oxygen shielding micro-zone to remove free oxygen, maintaining asymmetric gas pulse blowing at the bottom of the melt and standing still, so that the generated silicon dioxide inclusions float up and are adsorbed in the refining slag, and then the remaining silicon blocks and all aluminum ingots are added to complete alloying. The present application cooperates the feeding and the bottom blowing pulse flow field by time sequence decoupling, breaks the secondary oxidation chain of high-activity elements, accelerates the removal of inclusions, reduces the total oxygen content and the density of large-particle inclusions of the finished product, eliminates the physical pinning of magnetic domain walls, and reduces the high-frequency core loss and the coercive force.

Description

Technical Field

[0001] This invention relates to a method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel, belonging to the field of metal material recycling technology. Background Technology

[0002] Currently, using short-process smelting technology to recycle scrap steel into iron-silicon-aluminum soft magnetic alloys is an important way to improve the utilization value of scrap steel. Existing refining processes usually involve adding synthetic refining slag to the surface of the scrap steel melt and relying on the slag-metal reaction to gradually remove impurities such as oxygen and sulfur. However, scrap steel melt often contains high levels of dissolved oxygen and residual sulfur. If the refining process is regarded as a uniform and static equilibrium process, it is easy to ignore the actual mass transfer limitation at the slag-metal interface. At the contact point between the melt and the slag, a high-viscosity mass transfer boundary layer is usually formed. This boundary layer slows down the migration rate of unstable oxides from the depths of the molten pool to the slag layer, causing local areas of the molten pool to maintain a high oxygen potential, making it difficult to form an overall low-oxygen smelting environment before the addition of alloying elements.

[0003] To reduce the oxygen potential in the melt, the conventional approach is to increase the amount of deoxidizer or extend the refining time. However, excessive deoxidizer can easily cause the subsequent addition of active alloying elements such as silicon and aluminum to burn off. Excessive refining time can lead to sulfur return from the slag to the molten steel, making it difficult to simultaneously achieve melt purity and alloying element recovery. Especially when deoxidation is insufficient, directly adding silicon and aluminum to the melt will cause a significant secondary oxidation reaction with the dissolved oxygen, generating a large number of high-melting-point, finely dispersed non-metallic inclusions in a short time. These inclusions are difficult to float and are prone to remain in the solidified alloy matrix. Besides relying on hardware structures such as the melting furnace or specific crystallizing roller morphology to passively constrain the flow, the related processes also suffer from kinetic limitations in their control methods. For example, Chinese invention patent CN115537499B discloses a deoxidation method for silicon-phosphorus-reinforced high-strength IF steel, which attempts to suppress inclusion formation by adding ferrosilicon alloy and aluminum alloy in stages. However, it still relies on a one-dimensional linear formula based on the static initial composition after furnace exit. The constant circulation mode it sets is based on an ideal and uniform reaction system. When faced with the non-ideal working conditions of scrap steel recycling and soft magnetic alloying with drastic batch fluctuations and extremely complex compositions, this pure time-series control, which lacks an active intervention mechanism for the high viscosity mass transfer boundary layer at the slag-metal interface, is prone to the existence of flow dead zones, making it difficult for deoxidation products to agglomerate and grow. It may even cause serious slag entrapment and inclusion dispersion residues, which cannot meet the purity index requirements of high-performance soft magnetic alloys for total oxygen content and large particle inclusion density.

[0004] Therefore, how to reduce the mass transfer barrier at the slag-metal interface and distinguish between the deoxidation and impurity removal process and the alloying process in terms of process timing, so as to reduce secondary oxidation and inclusion residues, are problems that need to be solved in the process of recycling scrap steel into iron-silicon-aluminum alloys. Summary of the Invention

[0005] To address the problems in the background art, the technical solution of the present invention is as follows: A method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel, comprising the following steps:

[0006] Step S1: Add multi-component synthetic refining slag to the surface of the scrap steel melt, determine the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag, and control the optical alkalinity of the multi-component synthetic refining slag between 0.68 and 0.75 by adjusting the ratio of calcium oxide and silicon dioxide in the multi-component synthetic refining slag.

[0007] Step S2: When the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag drops to below 0.5%, the feeding channel is opened, and the first batch of metallic silicon blocks is added to the scrap steel melt. The mass of the first batch of metallic silicon blocks accounts for 60% to 70% of the total added silicon mass. A low-oxygen shielding micro-zone is constructed around the feeding channel to remove free dissolved oxygen from the scrap steel melt.

[0008] Step S3: Maintain asymmetric gas pulse purging at the bottom of the scrap steel melt. After the first batch of silicon metal blocks is added, let it stand for 6 to 10 minutes to allow the silica inclusions generated inside the scrap steel melt to float up and be adsorbed into the upper multi-component synthetic refining slag.

[0009] Step S4: After settling, the second portion of silicon metal blocks and all the aluminum metal ingots are fed into the feeding channel at once. The mass of the second portion of silicon metal blocks accounts for 30% to 40% of the total added silicon mass. The second portion of silicon metal blocks is used to block the direct contact between the aluminum metal ingots and the residual free oxygen in the low-oxygen shielded micro-area, thereby completing the alloying of recycled scrap steel.

[0010] Preferably, in step S3, the asymmetric gas pulse purging includes pressure step control: before the first batch of silicon metal blocks is added, the purging pulse pressure of the asymmetric inert gas is controlled at 0.4 MPa; after the first batch of silicon metal blocks is added, the purging pulse pressure of the asymmetric inert gas is stepped up to the shear pressure range of 0.6 MPa to 0.65 MPa, and the shear stress generated by the asymmetric gas flow at the slag-metal interface is used to destroy the mass transfer boundary layer at the slag-metal interface, thereby accelerating the diffusion and reduction of iron oxide and manganese oxide from deep within the scrap steel melt to the surface of the multi-component synthetic refining slag.

[0011] Preferably, in step S3, the asymmetric gas pulse purging adopts high-low frequency alternating pulse airflow control, including the following sub-steps: Step S31, in the initial stage of adding the first share of silicon metal block, a high-frequency pulse airflow of 8Hz to 12Hz is used to promote the convection diffusion of alloying elements in the scrap steel melt; Step S32, during the settling period, the low-frequency pulse airflow of 0.5Hz to 1.5Hz is switched to induce the scrap steel melt to generate circulation, promote the collision growth of silica inclusions and float to the multi-element synthetic refining slag with the circulation.

[0012] Preferably, in step S3, the asymmetric gas pulse purging is achieved by an asymmetric nozzle set at the bottom of the smelting furnace. The asymmetric nozzle set at the bottom of the smelting furnace has an inclination angle of 15° to 30° with the longitudinal axis of the smelting furnace and is eccentrically arranged below the feeding channel, so that the purging gas forms an asymmetric three-dimensional flow field inside the scrap steel melt.

[0013] Preferably, in step S1, the multi-component synthetic refining slag comprises, by mass percentage: 45% to 55% calcium oxide, 15% to 25% silicon dioxide, 10% to 20% aluminum oxide, and 8% to 15% calcium fluoride; the melting point of the multi-component synthetic refining slag is controlled at 1350°C to 1400°C.

[0014] Preferably, in steps S2 and S4, the temperature of the scrap steel melt is maintained at 1540°C to 1580°C; the particle size of the first share of silicon metal blocks and the second share of silicon metal blocks is 10mm to 30mm.

[0015] Preferably, in step S3, the viscosity of the multi-element synthetic refining slag during the settling period is controlled at 0.15 Pa·s to 0.35 Pa·s, and the internal flow velocity of the scrap steel melt is controlled at 0.2 m / s to 0.5 m / s, so that the slag metallographic contact angle of silica inclusions with a size greater than 2 μm during the flotation process is greater than 90°.

[0016] Preferably, in step S4, high-purity argon is used for surface scavenging protection before the aluminum ingot is added, and a positive pressure shield of high-purity argon is maintained above the feeding channel. The purity of the argon is not less than 99.999%, to prevent secondary oxidation of the aluminum ingot during the process of falling into the scrap steel melt.

[0017] Preferably, after step S4, an inert gas is introduced into the scrap steel melt for homogenization treatment for 3 to 5 minutes, and the total oxygen mass percentage content in the obtained iron-silicon-aluminum alloy melt is less than 15 ppm, and the number density of non-metallic inclusions with a size greater than 5 μm is less than 5 per mm².

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. In the method of recycling and processing iron-silicon-aluminum alloys from smelting scrap steel, by tracking the changes in the iron oxide and manganese oxide content in the multi-element synthetic refining slag, it is possible to promptly determine whether mass transfer is hindered at the slag-metal interface. When mass transfer slows down, the shearing effect at the slag-metal interface is enhanced by asymmetric gas pulse purging, which disturbs the mass transfer boundary layer that was originally attached to the vicinity of the interface. The oxides deep in the scrap steel melt are more likely to migrate to the refining slag side and be reduced and removed. In this way, it is no longer necessary to simply wait for the melt and slag to reach equilibrium on their own for a long time. This can reduce the local high oxygen area in the molten pool and make it easier for the scrap steel melt before alloying to maintain a low oxygen state.

[0020] 2. This invention separates the deoxidation and impurity removal process from the subsequent alloying process in terms of feeding sequence. First, a first portion of metallic silicon blocks is fed in, forming a low-oxygen shielding micro-zone around the feeding channel. This allows the residual free dissolved oxygen in the scrap steel melt to be consumed first, and allows time for silica inclusions to float into the multi-element synthetic refining slag. In this way, when the second portion of metallic silicon blocks and metallic aluminum ingots are fed in later, the metallic aluminum ingots are less likely to come into direct contact with high concentrations of residual oxygen, which can reduce the degree of alloy element burn-off and secondary oxidation reaction, and reduce the generation and residue of high-melting-point fine non-metallic inclusions in the melt.

[0021] 3. In this invention, asymmetric gas pulse purging in different states is used in conjunction with alloying and static impurity removal processes. This allows for more suitable flow conditions for the diffusion of alloying elements and the floating and removal of inclusions. The airflow disturbance at the initial feeding stage is conducive to the dispersion and dissolution of metallic silicon blocks and metallic aluminum ingots in the scrap steel melt. The low-frequency circulation during static removal is conducive to the collision, growth and floating of fine silica inclusions into the multi-element synthetic refining slag. This reduces the flow dead zone caused by single constant purging, making the distribution of alloying elements and the removal of deoxidation products more stable. Attached Figure Description

[0022] Figure 1 This is a flowchart of the process steps for preparing iron-silicon-aluminum alloy by smelting scrap steel according to the present invention;

[0023] Figure 2 This is a structural diagram of the control system for preparing iron-silicon-aluminum alloy by smelting scrap steel according to the present invention.

[0024] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0026] A method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel includes the following steps:

[0027] Step S1: Add multi-component synthetic refining slag to the surface of the scrap steel melt, determine the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag, and control the optical alkalinity of the multi-component synthetic refining slag between 0.68 and 0.75 by adjusting the ratio of calcium oxide and silicon dioxide in the multi-component synthetic refining slag.

[0028] Step S2: When the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag drops to below 0.5%, the feeding channel is opened, and the first batch of metallic silicon blocks is added to the scrap steel melt. The mass of the first batch of metallic silicon blocks accounts for 60% to 70% of the total added silicon mass. A low-oxygen shielding micro-zone is constructed around the feeding channel to remove free dissolved oxygen from the scrap steel melt.

[0029] Step S3: Maintain asymmetric gas pulse purging at the bottom of the scrap steel melt. After the first batch of silicon metal blocks is added, let it stand for 6 to 10 minutes to allow the silica inclusions generated inside the scrap steel melt to float up and be adsorbed into the upper multi-component synthetic refining slag.

[0030] Step S4: After settling, the second portion of silicon metal blocks and all the aluminum metal ingots are fed into the feeding channel at once. The mass of the second portion of silicon metal blocks accounts for 30% to 40% of the total added silicon mass. The second portion of silicon metal blocks is used to block the direct contact between the aluminum metal ingots and the residual free oxygen in the low-oxygen shielded micro-area, thereby completing the alloying of recycled scrap steel.

[0031] Preferably, in step S3, the asymmetric gas pulse purging includes pressure step control: before the first batch of silicon metal blocks is added, the purging pulse pressure of the asymmetric inert gas is controlled at 0.4 MPa; after the first batch of silicon metal blocks is added, the purging pulse pressure of the asymmetric inert gas is stepped up to the shear pressure range of 0.6 MPa to 0.65 MPa, and the shear stress generated by the asymmetric gas flow at the slag-metal interface is used to destroy the mass transfer boundary layer at the slag-metal interface, thereby accelerating the diffusion and reduction of iron oxide and manganese oxide from deep within the scrap steel melt to the surface of the multi-component synthetic refining slag.

[0032] Preferably, in step S3, the asymmetric gas pulse purging adopts high-low frequency alternating pulse airflow control, including the following sub-steps: Step S31, in the initial stage of adding the first share of silicon metal block, a high-frequency pulse airflow of 8Hz to 12Hz is used to promote the convection diffusion of alloying elements in the scrap steel melt; Step S32, during the settling period, the low-frequency pulse airflow of 0.5Hz to 1.5Hz is switched to induce the scrap steel melt to generate circulation, promote the collision growth of silica inclusions and float to the multi-element synthetic refining slag with the circulation.

[0033] Preferably, in step S3, the asymmetric gas pulse purging is achieved by an asymmetric nozzle set at the bottom of the smelting furnace. The asymmetric nozzle set at the bottom of the smelting furnace has an inclination angle of 15° to 30° with the longitudinal axis of the smelting furnace and is eccentrically arranged below the feeding channel, so that the purging gas forms an asymmetric three-dimensional flow field inside the scrap steel melt.

[0034] Preferably, in step S1, the multi-component synthetic refining slag comprises, by mass percentage: 45% to 55% calcium oxide, 15% to 25% silicon dioxide, 10% to 20% aluminum oxide, and 8% to 15% calcium fluoride; the melting point of the multi-component synthetic refining slag is controlled at 1350°C to 1400°C.

[0035] Preferably, in steps S2 and S4, the temperature of the scrap steel melt is maintained at 1540°C to 1580°C; the particle size of the first share of silicon metal blocks and the second share of silicon metal blocks is 10mm to 30mm.

[0036] Preferably, in step S3, the viscosity of the multi-element synthetic refining slag during the settling period is controlled at 0.15 Pa·s to 0.35 Pa·s, and the internal flow velocity of the scrap steel melt is controlled at 0.2 m / s to 0.5 m / s, so that the slag metallographic contact angle of silica inclusions with a size greater than 2 μm during the flotation process is greater than 90°.

[0037] Preferably, in step S4, high-purity argon is used for surface scavenging protection before the aluminum ingot is added, and a positive pressure shield of high-purity argon is maintained above the feeding channel. The purity of the argon is not less than 99.999%, to prevent secondary oxidation of the aluminum ingot during the process of falling into the scrap steel melt.

[0038] Preferably, after step S4, an inert gas is introduced into the scrap steel melt for homogenization treatment for 3 to 5 minutes, and the total oxygen mass percentage content in the obtained iron-silicon-aluminum alloy melt is less than 15 ppm, and the number density of non-metallic inclusions with a size greater than 5 μm is less than 5 per mm².

[0039] Example 1: When smelting industrial scrap steel and processing ferrosilicon-aluminum alloys in a short-process electric arc furnace, the initial mass fraction of free dissolved oxygen in the scrap steel melt is greater than 150 ppm, and the mass fraction of residual sulfur is greater than 0.015%. If metallic silicon and metallic aluminum are directly added under these conditions, the free dissolved oxygen can easily trigger a secondary oxidation reaction at the slag-metal interface and the charging area. At the same time, there is a fluid mass transfer dead zone in the smelting furnace, and a high-viscosity mass transfer boundary layer is easily formed at the interface between the scrap steel melt and the slag, which hinders the diffusion of unstable oxides from the depth of the molten pool to the slag layer. This makes it difficult to form a stable low-oxygen environment before alloying, and generates high-melting-point, diffusely distributed non-metallic inclusions in the melt. These inclusions remain in the solidified alloy matrix and will physically pin the magnetic domain walls, affecting grain growth and increasing the high-frequency core iron loss and coercivity of the finished product.

[0040] To reduce the mass transfer resistance at the slag-metal interface, a multi-component synthetic refining slag is first added to the surface of the molten scrap steel. This multi-component synthetic refining slag comprises 50% by mass of... 20% 15% And 15% ,in It is calcium oxide. It is silicon dioxide. It is aluminum oxide. It is calcium fluoride, and all components are expressed as a percentage by mass. This is achieved by adjusting the composition of the multi-component synthetic refining slag. and The proportions are adjusted to control the optical basicity of the multi-component synthetic refining slag at 0.72. This closed-loop fine-tuning of optical basicity is based on the dynamic calculation of the electron-donating capacity of all components of the slag. Specifically, the adjustment path is as follows: the control chip reads the filtered effective arithmetic mean voltage signal converted from the ionization sensor at the furnace wall at 15-second intervals. The control chip contains a conductivity polarization response benchmark regression function. The read voltage signal is input into this function to calculate the dynamic residual mass percentages of iron oxide and manganese oxide in the current slag online. The control chip then adjusts the dynamic residual mass percentages in real time based on these percentages. The corrected ratio of calcium oxide to silica required to maintain a constant optical alkalinity of 0.72 was calculated. A pulsed current signal was then output to the pneumatic feeding and weighing machine of the actuator to adjust its discharge valve opening. By dynamically increasing or decreasing the instantaneous feeding rate of high-alkalinity calcium oxide blocks or low-alkalinity silica blocks, the slag alkalinity shift caused by the decrease in the concentration of variable-valence oxides was automatically compensated. This achieved fully automatic closed-loop fine-tuning of the slag composition, stabilizing its melting point at 1380℃ and maintaining the viscosity at 0.25 Pa·s during the settling period. During ratio adjustments, the control... The system matches the optical alkalinity target value based on the real-time measured mass percentage content of iron oxide and manganese oxide: when the mass percentage content of iron oxide and manganese oxide is between 1.5% and 2.0%, the optical alkalinity target value is set to 0.68, and the mass ratio of calcium oxide to silicon dioxide is adjusted to 2.0:1.0; when the mass percentage content of iron oxide and manganese oxide drops to between 1.0% and 1.4%, the optical alkalinity target value is adjusted to 0.72, and the mass ratio of calcium oxide to silicon dioxide is increased to 2.5:1.0; when iron oxide... When the mass percentage content of manganese oxide is further reduced to between 0.5% and 0.9%, the target value of optical alkalinity is set to 0.75, and the mass ratio of calcium oxide to silicon dioxide is increased to 3.0 to 1.0. In this embodiment, the monitored mass percentage content of iron oxide and manganese oxide is initially in the range of 1.0% to 0.8%. The control system executes the second adjustment logic and adds calcium oxide and silicon dioxide blocks with a mass ratio of 2.5 to 1.0 through a pneumatic feeding and weighing machine to control the optical alkalinity of the multi-element synthetic refining slag at 0.72.

[0041] In the continuous monitoring of multi-component synthetic refining slag and During the process of mass percentage content, It is iron oxide. Both are manganese oxide, and both are expressed as a percentage by mass. When observed and When the mass percentage content of the gas decreases to the range of 1.0% to 0.8%, and the transient concentration decay rate is less than 0.05% per minute, the purging pulse pressure of the asymmetric inert gas introduced into the bottom of the molten pool is increased from 0.4 MPa to 0.62 MPa through an asymmetric nozzle located at the bottom of the molten furnace and inclined at an angle of 22° to the longitudinal axis of the molten furnace. The specific implementation of the gas flow path and purging sequence of the asymmetric gas pulse purging is as follows: the gas is purged by a single directional nozzle at the bottom of the molten furnace, which is eccentrically arranged at the bottom of the molten furnace with an eccentric distance of 0.4 times the radius of the furnace bottom. The gas used is industrial high-purity argon with a purity of not less than 99.99%, and the gas flow direction forms a 2° angle with the longitudinal axis of the furnace body. A fixed tilt angle of 2° drives an asymmetric three-dimensional spiral flow field within the molten scrap to eliminate dead zones. The pulse input is executed by a proportional regulating valve in the bottom-blowing air path, driven by a square wave electrical signal output from the control chip. The duty cycle of the square wave pulse is controlled at 50%, the purge pulse pressure of the high-pressure sustaining phase is locked at 0.62 MPa, and the purge pressure of the low-pressure reference phase is controlled at 0.15 MPa. The total duration of each complete pulse cycle is fixed at 1.0 second. Through the cyclical alternation of high and low pressures, continuous shear stress is generated at the slag-metal interface. This shear stress generated at the slag-metal interface by the asymmetric airflow disrupts the mass transfer boundary layer, promoting flow deep within the molten scrap. and It diffuses onto the surface of the multi-component synthetic refining slag and undergoes a reduction reaction, causing the multi-component synthetic refining slag to diffuse into the slag. and The mass percentage content drops below 0.5% before feeding. The transient concentration decay rate is obtained by the central processing unit through a sliding time difference algorithm: the processor reads the filtered component data in 10-second cycles, continuously calculates the mass percentage difference between the current moment and the previous minute, and obtains the absolute change in phase concentration within 1 minute; when the change is below 0.05% for 3 consecutive acquisition cycles, the control system outputs a step control electrical signal to the proportional regulating valve of the furnace bottom gas path, causing the regulating valve opening to increase instantaneously, and increasing the purging pulse pressure of the asymmetric inert gas from 0.4MPa to 0.62MPa within 1 second.

[0042] In the multi-component synthetic refining slag and After the mass percentage content of silicon stabilizes below 0.5%, the feeding channel, eccentrically arranged above the asymmetric nozzle, is opened, and a first fraction of silicon metal blocks with a particle size of 20mm are added to the molten scrap. The added mass of the first fraction of silicon metal blocks accounts for 65% of the total added silicon mass. A low-oxygen shielding micro-zone is constructed around the feeding channel. In terms of physical morphology, this micro-zone is a locally inverted cone-shaped silicon-rich functional zone of molten steel with a diameter of 350mm to 450mm, centered on the vertical point of the center line of the eccentric feeding channel. By adding the first fraction of silicon metal blocks, the local mass fraction of silicon in this zone is instantaneously enriched to an enrichment state of 1.5% to 2.5%. This highly active silicon... The elements, through in-situ reduction reactions, powerfully consume the free oxygen in the melt, forcibly reducing the free dissolved oxygen content in this zone within 50 seconds and maintaining it at an ultra-low oxygen quantitative threshold below 10 ppm. This spontaneously forms a low-oxygen potential fluid barrier functional zone within the melt, surrounding the entire subsequent alloy falling path, and in-situ removes residual free dissolved oxygen from the scrap steel melt. After the first batch of metallic silicon blocks is added, it is allowed to stand for 8 minutes. Simultaneously, in conjunction with bottom-blowing airflow control, the pulse frequency of the bottom-blowing inert gas is switched from a 10Hz high-frequency pulse airflow used to promote the convection and diffusion of alloying elements to a 1.0Hz low-frequency pulse airflow, inducing overall circulation within the scrap steel melt. Inclusions collide and grow in the circulation, float to the surface with the circulation and are adsorbed into the upper multi-component synthetic refining slag, thus completing the deoxidation and impurity removal before alloying.

[0043] After settling, the second portion of silicon metal blocks and all aluminum ingots are fed into the feeding channel in one go. The mass of the second portion of silicon metal blocks accounts for 35% of the total added silicon mass. Before the aluminum ingots are added, the surface is protected by high-purity argon gas with a purity of not less than 99.999%, and a positive pressure shield of high-purity argon gas is maintained above the feeding channel. After the second portion of silicon metal blocks enters the low-oxygen shielded micro-zone, that is, after entering the silicon-rich functional zone of the locally inverted cone-shaped molten steel with a free dissolved oxygen content of less than 10ppm and a diameter of 350mm to 450mm, which has been treated by the first portion of silicon metal blocks, the silicon metal blocks first come into contact with the residual free oxygen and undergo a deoxidation reaction around the aluminum ingots, blocking the direct contact between the aluminum ingots and the residual free oxygen, so that the aluminum ingots are dissolved in the scrap steel melt in the low-oxygen shielded micro-zone. Subsequently, inert gas is introduced into the scrap steel melt for homogenization treatment for 4 minutes, so that the alloying elements are further dispersed evenly in the melt.

[0044] After solidification, the number density of non-metallic inclusions larger than 5 μm in the final iron-silicon-aluminum alloy melt decreased to 2.8 inclusions / mm², the total oxygen mass percentage content was controlled below 12 ppm, and the total sulfur mass percentage content was stabilized below 0.004%. Due to the reduction in the amount of non-metallic inclusions, the physical pinning effect of the magnetic domain walls in the solidified iron-silicon-aluminum soft magnetic alloy matrix was weakened, and the grain growth process was smoother. Under the conditions of 50 kHz working frequency and 0.1 T working magnetic flux density, the high-frequency core iron loss was reduced by 36% to 180 W / kg, and the coercivity was reduced to below 2.2 A / m.

[0045] Example 2: To verify the effectiveness of deoxidation and impurity removal at the slag-metal interface and purity control during the short-process electric arc furnace refining process, this example was conducted on a 50t dual-furnace electric arc furnace refining platform equipped with an asymmetric gas pulse purging system at the bottom. The asymmetric nozzle at the bottom of the refining furnace was tilted at an angle of 22° to the longitudinal axis of the furnace body, used to continuously introduce high-purity nitrogen gas into the bottom of the scrap steel melt; the gas flow rate ranged from 0 to 150 m³ / h, and the pressure adjustment ranged from 0 to 1.0 MPa. Within the smelting temperature range of 1550℃ to 1650℃, the temperature control accuracy of this refining furnace was [not specified]. The temperature was ±5℃. The test object was industrial recycled steel melt containing an initial high concentration of free dissolved oxygen and sulfur. During the test, the ionization sensor installed on the furnace wall collected the original ionization polarization voltage signal at the slag-metal interface, and the data sampling frequency was set to 20Hz. When the concentration decay rate of iron oxide and manganese oxide in the refining slag was less than 0.05% per minute, the control unit adjusted the valve opening to step increase the purging pulse pressure of the asymmetric inert gas from the normal 0.4MPa to 0.62MPa, so that the asymmetric gas flow generated shear stress at the slag-metal interface, thereby destroying the mass transfer boundary layer.

[0046] At the start of smelting, a multi-component synthetic refining slag obtained through offline batching is applied to the surface of the molten scrap steel. This slag is formulated by mass percentage of calcium oxide, silica, alumina, and calcium fluoride. Five optical alkalinity sample groups are created by varying the ratio of calcium oxide to silica. Gaussian white noise with a signal-to-noise ratio of 20 dB is introduced into the acquisition system to simulate power frequency harmonic interference during high-power smelting. The control unit incorporates a sliding time window filter operator and establishes a first-in-first-out circular queue in memory covering 20 data samples, corresponding to a 1-second time window. At each sampling moment, the control unit displays the latest acquired raw electrical data. The ionization polarization voltage signal is written to the tail of the queue, while the oldest sample at the head of the queue is discarded. The 20 voltage values ​​in the queue are then averaged to obtain the filtered effective ionization polarization voltage. The control unit internally establishes the baseline linear equation for the conductivity polarization response. For every 10mV increase in polarization voltage, the mass percentage content of iron oxide and manganese oxide increases linearly by 0.1%. When the polarization voltage of the filtered output is in the range of 50mV to 100mV, the mass percentage content of iron oxide and manganese oxide is between 0.5% and 1.0%, thereby realizing online monitoring of the iron oxide and manganese oxide content in the multi-element synthetic refining slag.

[0047] In the five optical alkalinity sample groups, the mass percentages of calcium oxide, silicon dioxide, aluminum oxide, and calcium fluoride in the control sample group one were 42%, 28%, 15%, and 15%, respectively. The optical alkalinity calibration value was 0.61, the melting point was 1435℃, and the slag phase viscosity at 1580℃ was 0.52 Pa·s. When the silicon dioxide content was high, the degree of polymerization of silicon-oxygen tetrahedral anions in the slag phase network structure increased, resulting in increased slag phase viscosity and consequently increased mass transfer resistance at the slag-metal interface. The calcium oxide and silicon dioxide content in the control sample group one of this invention... The mass percentages of alumina and calcium fluoride in sample group two of this invention are 48%, 24%, 14%, and 14%, respectively. The optical alkalinity calibration value is 0.68, the melting point is 1395℃, and the slag phase viscosity at 1580℃ is 0.31 Pa·s. The mass percentages of the four components in sample group three of this invention are 50%, 20%, 15%, and 15%, respectively. The optical alkalinity calibration value is 0.72, the melting point is 1380℃, and the slag phase viscosity at 1580℃ is 0.25 Pa·s. The mass percentages of the four components in the control group were 52%, 17%, 16%, and 15%, respectively. The optical alkalinity calibration value was 0.75, the melting point was 1365℃, and the slag phase viscosity at 1580℃ was 0.19 Pa·s. The mass percentages of the four components in control group two were 56%, 12%, 17%, and 15%, respectively. The optical alkalinity calibration value was 0.81, the melting point was 1460℃, and the slag phase viscosity at 1580℃ was 0.68 Pa·s. When the calcium oxide content exceeded the upper limit, the slag phase viscosity exceeded the lower limit. Melting point eutectic saturation, precipitation of dicalcite free solid microcrystals at high temperatures, simultaneously increase melting point and slag viscosity, and weaken the wetting and adsorption capacity of multi-component synthetic refining slag for non-metallic inclusions. As can be seen from the above data, when the optical basicity is between 0.68 and 0.75, the melting point of the multi-component synthetic refining slag is between 1365℃ and 1395℃, and the slag viscosity measured at 1580℃ is between 0.19 Pa·s and 0.31 Pa·s; beyond this range, the slag viscosity increases to 0.52 Pa·s and 0.68 Pa·s, respectively.

[0048] In this embodiment, the combined mass percentage of calcium fluoride and alumina in the multi-component synthetic refining slag is controlled between 25% and 35%, and an optical basicity of 0.72 is used to maintain a relatively stable flow state of the molten slag phase within the refining temperature window of 1540°C to 1580°C. When the melt temperature approaches 1540°C, calcium fluoride reduces the degree of polymerization of the slag phase network structure and inhibits the increase in viscosity. When the temperature approaches 1580°C, alumina participates in the regulation of the slag phase structure and inhibits excessive viscosity reduction. Taking sample group two of the present invention as an example, the fluctuation range of its slag phase viscosity within this temperature range does not exceed ±0.02 Pa·s and is maintained at around 0.25 Pa·s, which can provide slag phase conditions with low resistance for the subsequent flotation and adsorption of silica inclusions.

[0049] To verify the inhibitory effect of stepwise, sequential, and decoupled addition on secondary oxidation, the multi-component synthetic refining slag of sample group two of this invention was used as a smelting control. Three levels of scrap steel with low, medium, and high impurity oxygen potential were used. After the mass percentage of iron oxide and manganese oxide in the multi-component synthetic refining slag of sample group two was reduced to below 0.5%, a first-component metallic silicon block, accounting for 65% of the total silicon mass, was added through the feeding channel. A low-oxygen shielding micro-zone was constructed around the feeding channel. After standing for 8 minutes, the bottom blowing frequency was switched from 10Hz to a 1.0Hz low-frequency pulsed airflow. The scrap steel melt is made into an overall circulating flow, which promotes the collision growth of silica inclusions and their adsorption in the multi-component synthetic refining slag. Then, the remaining 35% of the second share of metallic silicon blocks and all the metallic aluminum ingots protected by high-purity argon surface scavenging are added to complete the alloying. The comparative sample group three uses the same multi-component synthetic refining slag as the sample group two of this invention, but after the mass percentage content of iron oxide and manganese oxide drops to below 0.5%, all the metallic silicon blocks and metallic aluminum ingots are directly mixed and added into the feeding channel at one time, without staged addition or low-frequency pulse airflow static switching.

[0050] Under low-oxygen potential scrap steel raw materials, the initial total oxygen content of the scrap steel in sample group two of this invention was 152 ppm, the mass percentage content of iron oxide and manganese oxide in the slag was 0.42%, the transient temperature rise during secondary oxidation during alloying was 8°C, the number density of non-metallic inclusions larger than 5 μm in the finished product was 2.1 inclusions / mm², the total oxygen mass percentage content of the finished product was 9 ppm, the core loss was 171 W / kg under 50 kHz and 0.1 T conditions, and the coercivity was 1.95 A / m. In contrast, under the conditions of an initial total oxygen content of 151 ppm in scrap steel and a mass percentage content of iron oxide and manganese oxide in the slag of 0.43%, due to the one-time input of metallic silicon blocks and metallic aluminum ingots, the transient temperature rise during secondary oxidation during alloying reached 45°C, the number density of non-metallic inclusions larger than 5 μm in the finished product was 8.5 inclusions / mm², the total oxygen mass percentage content of the finished product was 38 ppm, the core loss was 255 W / kg, and the coercivity was 3.85 A / m.

[0051] Under the condition of medium oxygen potential scrap steel raw materials, the initial total oxygen content of the scrap steel in sample group two of this invention is 168 ppm, and the mass percentage content of iron oxide and manganese oxide in the slag is 0.45%. After the stepwise addition and low-frequency pulsed airflow settling treatment as described above, the transient temperature rise of secondary oxidation during alloying is 11°C, the number density of non-metallic inclusions larger than 5 μm in the finished product is 2.8 inclusions / mm², the total oxygen mass percentage content of the finished product is 12 ppm, the core loss is 180 W / kg, and the coercivity is 2.12 A / m. In contrast, under the condition of an initial total oxygen content of 170 ppm in the scrap steel and a mass percentage content of iron oxide and manganese oxide in the slag of 0.46%, the transient temperature rise of secondary oxidation during alloying is 58°C, the number density of non-metallic inclusions larger than 5 μm in the finished product is 11.2 inclusions / mm², the total oxygen mass percentage content of the finished product is 47 ppm, the core loss is 282 W / kg, and the coercivity is 4.31 A / m.

[0052] Under high oxygen potential scrap steel conditions, the initial total oxygen content of the scrap steel in sample group two of this invention was 185 ppm, and the mass percentage content of iron oxide and manganese oxide in the slag was 0.48%. After initial deoxidation by the first batch of metallic silicon blocks, 8 minutes of settling, and 1.0 Hz low-frequency pulsed airflow for impurity removal, the transient temperature rise during secondary oxidation in the alloying process was controlled at 14°C. The number density of non-metallic inclusions larger than 5 μm in the finished product was 3.2 inclusions / mm², and the total oxygen mass percentage content of the finished product was 14 ppm. The core loss... The core loss was 189 W / kg, and the coercivity was 2.26 A / m. The corresponding control group three, under the conditions of initial total oxygen content of scrap steel of 184 ppm and mass percentage content of iron oxide and manganese oxide in slag of 0.44%, the transient temperature rise of secondary oxidation during alloying reached 72℃. The number density of non-metallic inclusions larger than 5 μm in the finished product was 14.6 / mm², the mass percentage content of total oxygen in the finished product was 59 ppm, the core loss was 315 W / kg, and the coercivity was 5.12 A / m.

[0053] Based on the above three sets of oxygen potential gradient data, comparing sample group three, during the process of increasing the initial total oxygen content of scrap steel from 151ppm to 184ppm, due to the lack of the first portion of silicon metal block for pre-deoxidation and low-frequency pulsed airflow for static impurity removal, the strong active element directly contacts the residual free oxygen after being introduced. The transient temperature rise of secondary oxidation increased from 45℃ to 72℃, the number density of non-metallic inclusions larger than 5μm in the finished product increased from 8.5 inclusions / mm² to 14.6 inclusions / mm², the total oxygen mass percentage content of the finished product increased from 38ppm to 59ppm, the coercivity increased from 3.85A / m to 5.12A / m, and the core loss at a 50kHz operating frequency increased from 255W / kg to 315W / kg. In comparison, the present invention's sample... Group 2, under the conditions of initial total oxygen content of scrap steel of 152ppm to 185ppm and mass percentage content of iron oxide and manganese oxide in slag of 0.42% to 0.48%, firstly, a first proportion of metallic silicon blocks is added to remove free dissolved oxygen in situ. During the settling period, the flow is switched to a 1.0Hz low-frequency pulsed airflow, which causes silica inclusions to collide and grow in the circulation and be adsorbed by multi-element synthetic refining slag. During alloying, the transient temperature rise of secondary oxidation is controlled at 8℃ to 14℃. The number density of non-metallic inclusions larger than 5μm in the finished product is controlled at 2.1 inclusions / mm² to 3.2 inclusions / mm². The mass percentage content of total oxygen in the finished product is controlled at 9ppm to 14ppm, and the mass percentage content of total sulfur is stable below 0.004%.

[0054] The experimental data of this embodiment show that after the mass percentage content of iron oxide and manganese oxide is reduced to below 0.5%, the first portion of metallic silicon blocks is added first, followed by static removal of impurities by low-frequency pulsed airflow, which can reduce the secondary oxidation temperature rise and residual inclusions in the finished product during alloying. Subsequently, after the second portion of metallic silicon blocks is added and alloyed with all the metallic aluminum ingots, the non-metallic inclusions in the iron-silicon-aluminum soft magnetic alloy matrix are reduced, and the physical pinning effect of the magnetic domain walls is weakened. Under the conditions of a working frequency of 50kHz and a working magnetic flux density of 0.1T, the high-frequency core iron loss of sample group two of this invention is stable at about 180W / kg, and the coercivity is reduced to below 2.2A / m. This establishes a correspondence between the refining slag composition, feeding sequence, purging frequency, and the total oxygen content, inclusion number density, and soft magnetic performance indicators of the finished product.

[0055] Example 3: After the first batch of silicon metal blocks is added, the fine silica inclusions generated inside the scrap steel melt need to collide and grow under the action of static setting and low-frequency pulsed airflow, and then float and adsorb onto the multi-component synthetic refining slag. During the short-process recycling smelting process, the erosion of the furnace wall refractory material will change the geometry of the molten pool cross-section, and the viscous shear resistance inside the scrap steel melt will also change the movement trajectory and floating speed of the silica inclusions; if the forced static setting time window is... and low-frequency pulse switching frequency If the pulse frequency is not matched with the current furnace conditions, insufficient settling time may occur, fine inclusions may not float to the surface, or the pulse frequency may be close to the molten pool surface fluctuation period, resulting in slag contamination. This can lead to a large number of dispersed inclusion particles remaining in the iron-silicon-aluminum soft magnetic alloy matrix.

[0056] To determine the forced settling time window and low-frequency pulse switching frequency The control chip of the refining control system receives three initial input parameters: the refining temperature of the scrap steel melt is measured online by a radiation pyrometer installed in the middle of the refining furnace. In this embodiment The temperature was 1580℃; the static depth of the molten pool in the refining furnace was collected using an industrial ultrasonic level gauge. The measured value was 1.25 m; the slag phase viscosity of the multi-component synthetic refining slag was determined from the output of the previous calibration step. Its value is 0.25 Pa·s. The control chip reads the molten scrap steel from the memory. The viscosity correction factor is used to calculate the dynamic viscosity of the scrap molten steel under the current operating conditions. The value was 0.0052 Pa·s, and based on the multiphase fluid dynamics boundary conditions of inclusions, the average critical particle size of primary nuclei of silica inclusions in molten scrap steel was determined. The density of molten scrap steel is 5μm. for Intrinsic density of silica solid inclusions for .

[0057] The control chip calls the crystal nucleus free settling velocity calculation program to calculate the initial free settling velocity of a single silica inclusion crystal nucleus inside the scrap steel melt. The specific white-box calculation and flow rules implemented are as follows: First, the three independent process values—gravitational acceleration 9.8 m / s², the square of the average critical particle size of silica inclusions (5 μm), and the physical density difference obtained by subtracting the density of molten scrap steel (7100 kg / m³) from the intrinsic density of silica solid inclusions (2200 kg / m³)—are continuously multiplied arithmetically to obtain the total momentum term for upward buoyancy; then, the constant 18 is multiplied by the dynamic viscosity of molten scrap steel (0.00) under the current thermal state. Arithmetic multiplication of 52 Pa·s is performed to obtain the viscous fluid damping term. Finally, the total momentum term for upward buoyancy is divided by the viscous fluid damping term. This allows for a closed-loop calculation of the initial free settling velocity of a single particle from bottom to top, eliminating all algebraic placeholders and superscript variables. After executing the above natural language arithmetic rules, the control chip outputs a velocity of 0.0001285 m / s. This velocity corresponds to the upward buoyancy of the inclusion in the actual direction of motion. Substituting these parameters into the formula, the control chip obtains... for .

[0058] Calculating the forced resting time window At that time, the control chip uses the static depth of the molten pool Characterizes the distance that inclusions need to travel from the bottom of the molten pool to the multi-component synthetic refining slag, and incorporates the slag phase viscosity measurement value. Related fluid damping topology gain operator This method is used to correct the upward floating process of fine inclusions after collision and growth under the action of circulation. The specific calculation steps are as follows: The control chip first extracts the static depth of the molten pool (1.25m) under the current operating conditions from the read-only memory, and retrieves the corresponding fluid damping agglomeration gain operator 11.5 from the discrete mapping table based on the real-time slag viscosity measurement value (0.25Pa·s). The static depth value of the molten pool is arithmetically multiplied with the value of the fluid damping agglomeration gain operator to obtain the equivalent total upward floating distance term after circulation agglomeration growth correction. Then, the equivalent total upward floating distance term is divided by the calculated initial free settling velocity of a single particle (0.0001285m / s) to directly calculate the output impurity removal time window as 484 seconds in the time dimension. This is then converted and rounded to 8 minutes and written into the timing execution register of the refining control system. Determined by a pre-installed discrete relation mapping table within the control chip: when When it is in the range of 0.15 Pa·s to 0.20 Pa·s, Set to 9.2; when When it is in the range of 0.21 Pa·s to 0.30 Pa·s, Set to 11.5; when When it is in the range of 0.31 Pa·s to 0.35 Pa·s, The value is set to 13.8 in this embodiment. With a viscosity of 0.25 Pa·s, it falls into the second viscosity range, and the control chip accordingly uses 11.5 as the current viscosity. .

[0059] Complete the forced static time window After calibration, the control chip continues to calculate the low-frequency pulse switching frequency. The low-frequency pulse disturbance of bottom-blown inert gas is used to cause silica inclusions to collide and grow. Its frequency is matched with the melt circulation formed by the geometric inclination of the asymmetric nozzles in the refining furnace to reduce the risk of liquid surface resonance and slag entrapment caused by low-frequency purging. The control chip reads the equivalent fluid cross-sectional area inside the furnace of the refining furnace. The area is 4.15 m², and the inherent hydraulic resonant frequency of the melt circulation is determined based on the fluid resonance conservation relationship. The frequency was 1.04Hz. Subsequently, the control system periodically read the current sampling timing; the cumulative lag time after the first share of silicon metal blocks was added did not reach... At that time, the control chip outputs a phase-locked control command to the bottom blowing air path regulating valve, so that... and Maintaining the correspondence and locking the actual driving frequency at 1.0Hz, after the cumulative lag time reaches 8 minutes, the bottom blowing air path regulating valve closes the low frequency switching mode and restores the steady-state homogenized gas flow rate.

[0060] When smelting using the above calibration results, the refining furnace operates with an 8-minute forced settling time window and a 1.0 Hz low-frequency pulse switching frequency. The silica inclusion nuclei collide and grow in the circulation path formed by the low-frequency pulse airflow, and the fine particles agglomerate into agglomerates with an average particle size greater than 45 μm in the circulation motion. At the end of the 8-minute settling, the agglomerated inclusions float to the surface with the fluid movement and are adsorbed into the top multi-element synthetic refining slag. After this process, the number density of non-metallic inclusions with a size greater than 5 μm in the finished product is reduced to 2.1 inclusions / mm². Under the conditions of a 50 kHz working frequency and a 0.1 T working magnetic flux density, the core loss of the iron-silicon-aluminum soft magnetic alloy is controlled below 180 W / kg, and the coercivity converges to below 2.2 A / m.

[0061] Example 4: This example combines Figures 1 to 2 The method for recycling and processing ferrosilicon-aluminum alloys from smelted scrap steel is explained, such as... Figure 1As shown, in step S1, multi-component synthetic refining slag is added to the surface of the molten scrap steel, and the mass percentage content of iron oxide and manganese oxide is measured. The optical alkalinity is controlled between 0.68 and 0.75 by adjusting the ratio of calcium oxide to silicon dioxide. In step S2, when the mass percentage of iron oxide and manganese oxide drops below 0.5%, the feeding channel is opened, and a first share of metallic silicon blocks, accounting for 60% to 70% of the total added silicon mass, is added to the molten scrap steel. A low-oxygen shielding micro-zone is constructed around the feeding channel to remove free dissolved oxygen. In step S3, the oxygen content is maintained at a certain level. The bottom of the scrap steel melt is purged with an asymmetric gas pulse. After the first batch of silicon metal blocks is added, it is allowed to stand for 6 to 10 minutes to allow the silica inclusions generated inside to float to the surface and be adsorbed into the upper multi-element synthetic refining slag. After the standing period in step S4, the second batch of silicon metal blocks, accounting for 30% to 40% of the total silicon mass added, and all the aluminum ingots are added to the feeding channel at once. The second batch of silicon metal blocks are used to block the direct contact between the aluminum ingots and the residual free oxygen in the low-oxygen shielded micro-region, thus completing the alloying.

[0062] like Figure 2 As shown, the detection and acquisition hardware includes an ionization sensor, an industrial ultrasonic level gauge, a radiation pyrometer, and an insertion-type high-frequency conductivity meter. The output of the detection and acquisition hardware is connected to the input of the control chip, transmitting the detection signal to the sliding time window filter operator, timing execution register, and crystal nucleus free settling velocity calculation program inside the control chip. The output of the control chip is connected to the input of the actuator hardware to output control commands to the bottom-blowing air path proportional regulating valve and the pneumatic feeding and weighing machine in the actuator hardware. The output of the bottom-blowing air path proportional regulating valve is connected to the asymmetric nozzle of the dual-furnace electric arc furnace refining platform, and the output of the pneumatic feeding and weighing machine is connected to the feeding channel of the dual-furnace electric arc furnace refining platform.

[0063] Example 5: After different batches of recycled scrap steel melt enter the refining furnace, the free dissolved oxygen and sulfur content will fluctuate with the batch of raw materials; the refining furnace lining will also be eroded as the service time increases, causing the geometric dimensions of the molten pool to deviate from the nominal design value. In order to ensure that subsequent asymmetric gas pulse purging, forced settling and staged charging can be performed according to the current furnace conditions, the control system starts the physical reference calibration program in the steel tapping and waiting state. This program takes the refining furnace as the measurement object and uses the gas path system with a pressure regulation accuracy of 0.01MPa at the furnace bottom and the ultrasonic ranging sensor with a furnace wall spatial resolution better than 1mm to calibrate the geometric boundary and fluid resistance boundary of the current furnace.

[0064] In the empty furnace state, the control unit drives the ultrasonic ranging sensor to emit a beam vertically downward from the furnace mouth reference plane, and determines the maximum furnace depth reference based on the round-trip flight time of the beam. After the scrap steel melt has completed the initial melting, the ultrasonic ranging sensor measures the transient spatial distance from the furnace mouth reference plane to the upper surface of the scrap steel melt. The control unit calculates the difference between the two distances to obtain the static depth of the molten pool of the scrap steel melt in the current smelting furnace cycle. The value is then written into the system storage unit to correct for geometric deviations caused by furnace lining erosion. Subsequently, the control unit drives the asymmetric nozzle at the furnace bottom to introduce a preset test gas flow rate of 50 m³ / h, and records the transient gas back pressure inside the nozzle at this flow rate. Based on the transient gas back pressure and the dynamic viscosity of the scrap steel melt... The positive correlation between them automatically fits the measured slag phase viscosity value of the current multi-component synthetic refining slag. The fluid damping topology gain operator is updated using a built-in discrete incremental mapping algorithm. , This is used to correct the collision growth rate of fine silica inclusions under the action of circulation during subsequent alloying, thereby completing the physical reference boundary locking of the current smelting batch.

[0065] In obtaining and Subsequently, the control unit executes closed-loop control with alloying timing isolation. When the mass percentage of iron oxide and manganese oxide in the multi-element synthetic refining slag drops below 0.5%, the system triggers a phased feeding process. First, a first share of metallic silicon blocks, accounting for 65% of the total silicon mass, is added to the scrap steel melt, forming a low-oxygen shielding micro-region around the feeding channel. The control unit continuously monitors the abrupt change characteristics of the ionization polarization voltage in this region. The specific monitoring steps and discrete data closed-loop control logic executed by the control unit are as follows: the control chip continuously reads the raw voltage signal output by the ionization sensor set at the furnace wall at a physical sampling frequency of 20Hz, and uses a first-in-first-out circular queue established in memory to calculate 20 values ​​within a one-second time window. The effective arithmetic mean of the original voltage sample, when the effective arithmetic mean voltage remains stable in the low-voltage stable range of 50 mV to 100 mV for three consecutive acquisition cycles, and the absolute voltage difference attenuation value per minute is less than 0.5 mV, indicates that the total mass percentage content of iron oxide and manganese oxide in the top multi-element synthetic refining slag has been completely reduced to below 0.5%. The diffusion reduction pull of the slag on the variable valence oxides deep in the melt has reached a thermodynamic equilibrium state. Based on this, the control chip directly outputs a high-level state control signal to trigger the phase-locked loop logic, switching the frequency of the furnace bottom inert gas purging pulse from 10 Hz for alloy element diffusion to a low-frequency pulse airflow of 1.0 Hz, inducing the scrap steel melt to form a directional circulating flow.

[0066] During low-frequency pulsed airflow operation, the control unit operates according to pre-calibrated parameters. Calculate the forced resting time window The discrete data chain flow rules invoked by its control unit are as follows: the calibrated fluid damping topology gain operator value is arithmetically multiplied with the static depth value of the molten pool measured and output by the ultrasonic ranging sensor in the physical reference calibration program, and the resulting product is used as the total numerator; then, the initial free settling velocity value, jointly determined by the current temperature's scrap steel melt viscosity, scrap steel melt density, intrinsic density of silica solid phase inclusions, and average critical particle size of inclusions, is used as the total denominator; the control chip outputs a precise forced settling time in seconds through a closed-loop operation of dividing the total numerator by the total denominator. When the lag time reaches the calculated target value of 8 minutes, the control unit cuts off the low-frequency pulse airflow and feeds the remaining 35% of the second share of silicon metal blocks and all the aluminum metal ingots into the feeding channel. The second share of silicon metal blocks preferentially contacts the residual free oxygen in the low-oxygen shielded micro-zone, blocking the direct contact between the aluminum metal ingots and the residual free oxygen, thereby reducing the risk of secondary oxidation of the aluminum metal ingots during the process of entering the scrap steel melt. Through the closed-loop control composed of the sensor measurement values, geometric reference values ​​and physical quantity calculation relationships, the control unit can adjust the settling time and low-frequency purging state according to the current furnace condition and stabilize the multiphase interface reaction during the alloying process.

[0067] Example 6: In the refining preparation process of short-process electric arc furnace smelting of industrial recycled scrap steel, the physicochemical state of the multi-component synthetic refining slag changes with the smelting batch and the condition of the furnace lining, causing its viscosity at the standard smelting temperature to deviate from the baseline value. To match the bottom-blown gas pulse pressure with the real-time slag condition, the control system performs offline baseline calibration before each batch of smelting starts. By measuring the electrical impedance characteristics of the multi-component synthetic refining slag, the slag phase viscosity measurement value is established. The mapping relationship between electrical parameters is used to calculate the purging pressure compensation. The benchmark.

[0068] At the start of calibration, the refining furnace was switched to induction heating mode. The control unit heated the multi-component synthetic refining slag to the calibration temperature of 1580°C, and the conductivity of the molten slag phase was measured using an insertion-type high-frequency conductivity meter. The unit is S / m; under the condition of maintaining a constant temperature, the transient reactance value at the slag-metal interface is read synchronously. The unit is Ω, and the control system will To determine whether the electrical state of the slag-metal interface is stable, when the transient reactance value remains within a stable range during continuous sampling, values ​​measured at the same time interval are used. Involved in slag phase viscosity conversion.

[0069] After completing the acquisition of electrical parameters, the control unit establishes... and The physical regression function between them: ,in, The value is the slag phase viscosity measured at the calibration temperature. For phase characteristic coefficients, As an environmental compensation constant, slag phase composition samples were collected from different smelting furnace cycles, and offline regression fitting was performed using the least squares method to determine the current furnace lining wear state. The value is 0.12. The value is set to 0.05, and the control chip stores this functional relationship in its memory logic; during subsequent refining cycles, if the value is measured in real time... When a drift occurs, the control unit calculates the corresponding value according to this function. And simultaneously update it to the physical property database of multi-component synthetic refining slag.

[0070] In the actual smelting cycle, the control unit is based on the updated... Fluid damping topology gain operator Perform dynamic calibration and calculate the purging pressure compensation accordingly. When calculated online When the viscosity exceeds 0.35 Pa·s, it indicates that the slag viscosity is higher than the low-resistance range required for static impurity removal. The control logic triggers the high-pressure purging mode, outputting an electrical signal to the bottom-blowing gas regulating valve to maintain the purging pulse pressure of the asymmetric inert gas at 0.65 MPa. When the pressure does not exceed 0.35 Pa·s, the control unit will restore the purging pulse pressure to the normal set value of 0.4 MPa. Through the above calibration and pressure regulation, the bottom blowing gas pulse pressure can be adjusted according to the viscosity change of the multi-component synthetic refining slag, so that the rupture efficiency of the mass transfer boundary layer at the slag-gold interface remains stable at different furnace ages.

[0071] After offline baseline calibration and pressure compensation control, the number density of non-metallic inclusions larger than 5 μm in the iron-silicon-aluminum alloy produced by smelting was stably maintained below 2.5 inclusions / mm², indicating that the calibration process can reduce the impact of the drift of the physicochemical properties of the multi-component synthetic refining slag on the deoxidation and impurity removal effect.

[0072] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel, characterized in that, Includes the following steps: Step S1: Add multi-component synthetic refining slag to the surface of the scrap steel melt, determine the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag, and control the optical alkalinity of the multi-component synthetic refining slag between 0.68 and 0.75 by adjusting the ratio of calcium oxide and silicon dioxide in the multi-component synthetic refining slag. Step S2: When the mass percentage content of iron oxide and manganese oxide in the multi-component synthetic refining slag drops to below 0.5%, the feeding channel is opened, and the first batch of metallic silicon blocks is added to the scrap steel melt. The mass of the first batch of metallic silicon blocks accounts for 60% to 70% of the total added silicon mass. A low-oxygen shielding micro-zone is constructed around the feeding channel to remove free dissolved oxygen from the scrap steel melt. Step S3: Maintain asymmetric gas pulse purging at the bottom of the scrap steel melt. After the first batch of silicon metal blocks is added, let it stand for 6 to 10 minutes to allow the silica inclusions generated inside the scrap steel melt to float up and be adsorbed into the upper multi-component synthetic refining slag. Step S4: After settling, the second portion of silicon metal blocks and all the aluminum metal ingots are fed into the feeding channel at once. The mass of the second portion of silicon metal blocks accounts for 30% to 40% of the total added silicon mass. The second portion of silicon metal blocks is used to block the direct contact between the aluminum metal ingots and the residual free oxygen in the low-oxygen shielded micro-area, thereby completing the alloying of recycled scrap steel.

2. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S3, the asymmetric gas pulse purging includes pressure step control: before the first batch of metal silicon blocks is added, the purging pulse pressure of the asymmetric inert gas is controlled to be 0.4 MPa; After the first batch of silicon metal blocks is added, the purging pulse pressure of the asymmetric inert gas is stepped up to the shear pressure range of 0.6MPa to 0.65MPa. The shear stress generated by the asymmetric airflow at the slag-metal interface is used to destroy the mass transfer boundary layer at the slag-metal interface and accelerate the diffusion and reduction of iron oxide and manganese oxide from deep within the scrap steel melt to the surface of the multi-component synthetic refining slag.

3. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S3, the asymmetric gas pulse purging adopts high and low frequency alternating pulse airflow control, including the following sub-steps: Step S31, in the initial stage of adding the first share of silicon metal block, a high frequency pulse airflow of 8Hz to 12Hz is used to promote the convection diffusion of alloying elements in the scrap steel melt; Step S32, during the settling period, the low frequency pulse airflow of 0.5Hz to 1.5Hz is switched to induce the scrap steel melt to generate circulation, promote the collision growth of silica inclusions and float to the multi-element synthesis refining slag with the circulation.

4. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S3, the asymmetric gas pulse purging is achieved by an asymmetric nozzle set at the bottom of the smelting furnace. The asymmetric nozzle set at the bottom of the smelting furnace has an inclination angle of 15° to 30° with the longitudinal axis of the smelting furnace and is eccentrically arranged below the feeding channel, so that the purging gas forms an asymmetric three-dimensional flow field inside the scrap steel melt.

5. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S1, the multi-component synthetic refining slag comprises, by mass percentage: 45% to 55% calcium oxide, 15% to 25% silicon dioxide, 10% to 20% aluminum oxide, and 8% to 15% calcium fluoride; the melting point of the multi-component synthetic refining slag is controlled at 1350℃ to 1400℃.

6. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In steps S2 and S4, the temperature of the scrap steel melt is maintained at 1540°C to 1580°C; the particle size of the first and second fractions of silicon metal blocks is 10 mm to 30 mm.

7. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S3, during the settling period, the viscosity of the multi-element synthetic refining slag is controlled between 0.15 Pa·s and 0.35 Pa·s, and the internal flow velocity of the scrap steel melt is controlled between 0.2 m / s and 0.5 m / s, so that the slag metallographic contact angle of silica inclusions with a size greater than 2 μm is greater than 90° during the flotation process.

8. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, In step S4, high-purity argon is used for surface scavenging protection before the aluminum ingot is added, and a positive pressure shield of high-purity argon is maintained above the feeding channel. The purity of the argon is not less than 99.999% to prevent secondary oxidation of the aluminum ingot during the process of falling into the scrap steel melt.

9. The method for recycling and processing ferrosilicon-aluminum alloys from smelting scrap steel according to claim 1, characterized in that, After step S4, inert gas is introduced into the scrap steel melt for homogenization treatment for 3 to 5 minutes. The total oxygen mass percentage content in the obtained iron-silicon-aluminum alloy melt is less than 15 ppm, and the number density of non-metallic inclusions with a size greater than 5 μm is less than 5 per mm².

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