Device and method for recycling phosphorus in steel slag by using pulsed electric field

Abstract

The invention discloses a device and method for recycling phosphorus in steel slag through a pulsed electric field, and belongs to the field of metallurgical solid waste treatment. The method comprises the following operation steps that the hot steel slag and the molten iron are placed in a pulsed electric field treatment device, and a good electric field action environment is ensured; a pulse electric field with specific frequency and voltage is applied, parameters of the pulse electric field can be adjusted according to actual conditions, separation of phosphorus is promoted by arranging positive and negative power supplies on the two sides of a melt, and application of the electric field can be performed in a periodic pulse or pulse sequence mode so as to enhance the effect. Effective separation of phosphorus in the steel slag is enhanced through the pulsed electric field, the optimal treatment frequency for treating the steel slag with different alkalinity is matched, phosphorus in the steel slag is effectively separated out, and the loss of electric energy and reagents is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical solid waste treatment, and more specifically, to a device and method for recovering phosphorus from steel slag by using a pulse electric field. Background Art

[0002] In the long steelmaking process (blast furnace → converter → LF → RH → CC) and short steelmaking process (electric furnace → converter → LF → RH → CC), as the quality of steel continues to improve, the amount of slag discharged is also increasing, and has exceeded 100 million tons in recent years. Therefore, under the dual pressure of environmental pollution and resource waste, the problem of rational utilization of slag needs to be solved.

[0003] At present, most enterprises adopt external treatment methods such as hot stewing, drum method, wind quenching, hot pouring, etc., which cause heat loss of steel slag. The high phosphorus and iron content of steel slag after cooling also limits its recycling. The methods for removing phosphorus from steel slag at home and abroad mainly include modified magnetic separation, hot reduction, acid leaching, ultra-gravity, capillary separation, etc., but they all have problems such as poor phosphorus removal effect, secondary environmental pollution, high processing cost and slow speed.

[0004] After searching, Chinese Patent Publication No.: CN117721256A discloses a system and method for efficient treatment of high-temperature molten steel slag for full resource utilization, and studies a dephosphorization device for dephosphorization of reduced iron water produced by smelting, which easily causes phosphorus volatilization and has a slow dephosphorization rate; Chinese Patent Publication No. CN114472464A discloses a method for efficient recovery of iron and phosphorus resources in phosphorus-containing steel slag, which recovers phosphorus resources after slag modification of phosphorus-containing steel slag, wherein the magnetic separation and heat treatment time are relatively long, which is not conducive to large-scale industrial application. Summary of the invention

[0005] 1. Technical problem to be solved by the invention

[0006] The purpose of the present invention is to provide a device and method for recovering phosphorus from steel slag by using a pulse electric field, which can effectively treat and recover PO4 in steel slag. 3- , strengthening the recycling of elements in steel slag, saving energy, fast speed and low cost, greatly improving economic benefits.

[0007] 2. Technical solution

[0008] In order to achieve the above object, the technical solution provided by the present invention is:

[0009] The present invention discloses a device for recovering phosphorus from steel slag by utilizing a pulse electric field, comprising a treatment furnace and electrodes, wherein hot molten iron is contained in the treatment furnace, and pre-melted steel slag is laid on the upper layer of the hot molten iron; wherein the anode of the electrode extends downward into the hot molten iron, and the cathode of the electrode extends downward into the pre-melted steel slag, and the anode and the cathode are respectively connected to a pulse power supply.

[0010] Furthermore, the anode and cathode are distributed in an upward and downward extension manner in the processing furnace, and the bottom end of the anode passes through the pre-melted slag and continues to extend downward into the hot molten iron; and a corundum tube is sheathed around the anode, and the corundum tube wraps the area where the anode passes through the pre-melted slag to protect the electrode and prevent slag-metal contact short circuit. In practice, corundum tubes can be sheathed around the anode and cathode for protection.

[0011] Furthermore, the anode is horizontally laid in the hot molten iron in the lower layer of the treatment furnace, at least one group of cathodes is vertically extended in the treatment furnace, and the bottom end of the cathode extends to the pre-melted slag in the upper layer.

[0012] Furthermore, a protective atmosphere access pipeline is also provided in the processing furnace, and the pipeline extends into the pre-melted steel slag for conveying the protective atmosphere inwardly, and specifically argon protective gas can be used to protect the electrode and prevent slag-gold contact short circuit.

[0013] The present invention also provides a method for recovering phosphorus in steel slag by using a pulse electric field. The device as described above is used to pre-melt the steel slag and silicon-containing solid waste. The pre-melted steel slag is poured into a treatment furnace filled with hot molten iron. Electrodes are inserted, the anode is inserted into the hot molten iron, and the cathode is inserted into the pre-melted steel slag. Then, a pulse electric field of a specific frequency is applied according to different slag alkalinity and carbon content in the molten iron. The pulse electric field is maintained for a certain period of time to enhance the effective separation of phosphorus in the steel slag.

[0014] In practice, the hot / cold steel slag and silicon-containing solid waste produced by the steel plant can be mixed and pre-melted in a certain proportion, and the pre-melted steel slag is poured into a slag pot or electric furnace filled with hot carbon-containing molten iron. Then insert the high-temperature electrode, the anode is inserted into the carbon-containing hot molten iron, and the cathode is inserted into the molten slag, and a pulsed electric field is applied to promote the reduction and recovery of phosphorus in the steel slag. The outer periphery of the anode and the cathode can be sleeved with a corundum tube, and the electrode extends from the corundum tube. The length of the extended section is the distance between the bottom of the electrode and the bottom of the corundum tube. This length is the extension length of the electrode in the melt, which is 1 / 4-1 / 2 of the depth of the melt, so as to prevent direct contact short circuit between slag and gold and protect the electrode from erosion. Finally, the phosphorus-containing molten steel produced by the pulsed electric field treatment for a certain period of time can be used as an alloy product for phosphorus-containing alloy smelting or high-grade ferrophosphorus; low-phosphorus slag can be used as liquid steel slag, directly as a steel slag dephosphorization agent for online recycling or as a sintering flux, building materials, agricultural fertilizers and other products.

[0015] The present invention studies the role of pulse electric field in recovering valuable elements in steel slag, overcomes the defects of traditional direct current and alternating current treatment methods, saves energy, accurately realizes the matching relationship between pulse electric field frequency and steel slag treatment, and further realizes the dual utilization of steel slag and valuable elements.

[0016] The present invention is mainly based on the electrophoresis theory of impurity element migration. Positively charged substances move to the negative electrode, and negatively charged substances move to the positive electrode. Compared with direct current and alternating current treatment methods, pulse current has a stronger ability to remove impurity elements and can greatly save electricity. Phosphorus in steel slag exists in the form of PO4 3- Different carbon contents in molten iron have different reducing abilities. The pulse electric field can enhance the reduction to generate P 3- , where P 3- and partially unreduced PO4 3- Both are negatively charged substances. Applying a pulse electric field makes PO4 3- and P 3- Move along the direction of the electric field to exert the stirring of the pulsed electric field and promote the purification of the slag. And by calculating the viscosity of the mixed ratio of steel slag and silicon-containing solid waste in the alkalinity range of 1.0-1.8, it is below 0.20pa·s, which is suitable for slag-gold reaction. According to this theory, this method further optimizes the specific frequency of the pulsed electric field applied to steel slags with different alkalinity, the carbon content of molten iron, and the electrode extension distance, and reasonably matches and optimizes the application method of the pulsed electric field to promote the reduction of iron and phosphorus in the slag within a certain period of time, solves the problem of drying out in the steel slag reduction process, and further promotes the recovery of phosphorus in the steel slag. The specific carbon content of molten iron, the mixing ratio of silicon-containing solid waste, and the optimal frequency of slag treatment with different alkalinity are as follows:

[0017] The carbon content of the molten iron is 0.5-1.5%. When the basicity (CaO / SiO2) of the slag after mixing the steel slag and the silicon-containing solid waste is 1.0-1.2, the pulse electric field frequency is controlled to be 0-100Hz. During the treatment process, the extension depth of the anode in the hot molten iron and the extension depth of the cathode in the pre-melted steel slag are 4-8cm respectively.

[0018] The carbon content of the molten iron is 1.5-2.5%. When the basicity (CaO / SiO2) of the slag after mixing the steel slag and the silicon-containing solid waste is 1.2-1.4, the pulse electric field frequency is controlled at 100-500Hz. During the treatment process, the extension depth of the anode in the hot molten iron and the extension depth of the cathode in the pre-melted steel slag are 7-10cm respectively.

[0019] The carbon content of the molten iron is 2.5-3.5%. When the basicity (CaO / SiO2) of the slag after mixing the steel slag and the silicon-containing solid waste is 1.4-1.6, the pulse electric field frequency is controlled at 500-800Hz. During the treatment process, the extension depth of the anode in the hot molten iron and the extension depth of the cathode in the pre-melted steel slag are 12-13cm respectively.

[0020] The carbon content of molten iron is 3.5-4.5%. When the basicity of slag (CaO / SiO2) after mixing steel slag and silicon-containing solid waste is 1.6-1.8, the pulse electric field frequency is controlled at 800-1000Hz. During the treatment process, the extension depth of the anode in the hot molten iron and the extension depth of the cathode in the pre-melted steel slag are 16-17cm respectively.

[0021] Furthermore, in the treatment furnace, the mass ratio of pre-melted slag to hot molten iron is 1:1-2.0, and an electric field reaction is applied at a high temperature of 1400-1450°C for 0.15-0.5h to simulate the high temperature state of pulsed electric field treatment applied to metallurgical slag after slagging.

[0022] Furthermore, the voltage of the pulsed electric field is -4.5-4.5V. The applicant has found that the forward voltage accounts for 70-90% of a pulse cycle, the no voltage accounts for 10%, and the reverse voltage accounts for 0-20% to achieve a good phosphorus recovery effect. The pulse waveform of 4.5V in the cycle is relatively long to give full play to the effect of the electric field. If the forward voltage is relatively short and the voltage is too large or too small, the best effect of phosphorus recovery cannot be achieved. At present, the applicant has studied that the best forward voltage is 70-90%; -4.5V and 0V account for a short period of time, which reduces the impact of some other elements on the electric field, enhances the effect of the pulsed electric field, and plays a stirring role of the pulsed electric field force, saving electrochemical energy.

[0023] Furthermore, the anode and cathode are respectively connected to the pulse power supply through a clamp and corresponding wires, the wires are made of copper wire, and the clamps are made of stainless steel; both the anode and cathode are rod-shaped electrodes, and the material is graphite.

[0024] 3. Beneficial effects

[0025] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0026] The present invention discloses a method for recovering phosphorus from steel slag by utilizing pulse electric field, proposes a new way of treating steel slag by utilizing pulse electric field, and has significant economic and environmental benefits. By utilizing pulse electric field enhancement technology, the treatment modes of molten iron with different carbon contents and steel slag with different alkalinity are matched at the optimal frequency, which significantly improves the treatment effect and saves electricity, and meets the needs of modern industry for high efficiency and reduced energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the recovery device in the embodiment;

[0028] Figure 2 A waveform diagram of a pulsed electric field in an embodiment;

[0029] Figure 3 Schematic diagram of the application process of the recovery device in the embodiment.

[0030] Explanation of the symbols in the schematic diagram:

[0031] 100. treatment furnace; 101. hot molten iron; 102. pre-melted slag; 103. corundum tube; 104. anode; 105. cathode; 106. fixture. DETAILED DESCRIPTION

[0032] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] The present invention will be further described below in conjunction with the embodiments.

[0035] Example 1

[0036] A method for recovering phosphorus from steel slag using a pulsed electric field in this embodiment includes the following steps:

[0037] S1. Place pre-melted slag 102 and hot molten iron 101 in a treatment furnace 100 and ensure a good electric field environment.

[0038] In this embodiment, some typical steel slag is mixed with silicon-containing compounds for modification, with a basicity of 1.0, and specific components of 37.48wt% CaO, 37.48wt% SiO2, 7.2wt% Al2O3, 0.75wt% MgO, 14.5wt% Fe2O3, 2.6wt% P2O5 and a small amount of impurities.

[0039] S2, applying a pulsed electric field of specific frequency and voltage according to different slag basicity and carbon content in molten iron;

[0040] S3, maintain the pulse electric field for a certain time to ensure that it effectively strengthens the effective separation of phosphorus in the steel slag, and remove phosphorus by electric field strengthening slag-gold redox reaction of the pre-melted steel slag 102 and the carbon-containing hot iron 101 after high temperature modification in step S1, wherein the slag-gold reaction condition is to mix the modified pre-melted steel slag 102 and the hot iron 101 in a mass ratio of 1: (1-2.0), and react at a temperature of 1400°C-1450°C for 0.15-0.5h, and in practice, the mixing ratio can be 1:1, 1:1.5, 1:1.8, 1:2, etc., and the reaction temperature can be controlled to be 1400°C, 1420°C, 1450°C, and the reaction time can be 0.15h, 0.25h, 0.45h, 0.5h. It is beneficial to promote the directional movement of phosphorus in the pre-melted steel slag 102 under pulse electric field strengthening, and the carbon content of the hot iron 101 used is 1.5%.

[0041] In this embodiment, low-alkalinity pre-melted steel slag 102 is poured into an electric furnace filled with carbon-containing hot molten iron 101. The experimental temperature is 1400°C, the slag-gold mass ratio is 1:1, and the heights of the pre-melted steel slag 102 and the hot molten iron 101 are calculated based on the melt density and the diameter of the electric furnace to be approximately 32.21 cm and 17.74 cm, respectively. Keep warm for 30 minutes to ensure that the pre-melted steel slag 102 melts evenly; then, the cathode 105 is inserted into the pre-melted steel slag 102 with an insertion depth of 8 cm, and the anode 104 with a corundum tube 103 is inserted into the hot molten iron 101 with an insertion depth of 6 cm. The extension depths of the cathode 105 and the anode 104 can be raised and lowered by a stainless steel clamp 106. A stable pulse electric field is applied externally by a pulse power supply, and the specific waveform is as follows Figure 2 As shown, the frequency of the applied pulse electric field is 0-100Hz, the output voltage is -4.5~4.5V, the reaction is 0.15h, and the forward voltage of 4.5V accounts for 70-90% of the pulse cycle, the voltage of 0V accounts for 10%, and the reverse voltage of -4.5V accounts for 0-20%. After the slag-gold reaction is completed, the slag sample is taken out with a quartz tube, and the phosphorus element in the slag is analyzed using an X-ray fluorescence spectrometer (XRF), and the phosphorus content in the molten iron is detected by an ICP-AES inductively coupled plasma atomic emission instrument. Finally, it is found that the P2O5 in the steel slag drops from 0.365wt% to 0.06wt% under the pulse electric field.

[0042] Table 1.1 Phosphorus content in treated slag (wt%)

[0043]

[0044] Table 1.2 Phosphorus content in molten iron after treatment (wt%)

[0045]

[0046]

[0047] Example 2

[0048] The method and process of recovering phosphorus from steel slag by using pulse electric field in this embodiment are basically the same as those in embodiment 1, except that: in this embodiment, some typical steel slag is mixed and modified with silicon-containing compounds, and the basicity is 1.2, and the specific components are 40.12wt% CaO, 33.43wt% SiO2, 7.2wt% Al 2O3, 0.75wt% MgO, 14.5wt% Fe2O3, 2.6wt% P2O5 and a small amount of impurities. The carbon content of the hot molten iron 101 used is 2.5%.

[0049] In this embodiment, low-alkalinity pre-melted steel slag 102 is poured into an electric furnace filled with carbon-containing hot molten iron 101. The experimental temperature is 1420°C, the slag-gold mass ratio is 1:1.5, and the heights of the pre-melted steel slag 102 and the hot molten iron 101 are calculated based on the melt density and the diameter of the electric furnace to be approximately 32.21 cm and 26.61 cm, respectively. Keep warm for 30 minutes to ensure that the pre-melted steel slag 102 melts evenly; then, the cathode 105 is inserted into the pre-melted steel slag 102, and the anode 104 with a corundum tube 103 is inserted into the hot molten iron 101, and the electrode insertion depths are 8 cm. The extension depths of the cathode 105 and the anode 104 can be raised and lowered by the clamp 106, respectively. A stable pulse electric field is applied externally by a pulse power supply, and the specific waveform is as follows Figure 2 As shown, the frequency of the applied pulse electric field is 100-500Hz, the output voltage is -4.5~4.5V, and the reaction time is 0.25h. After the slag-gold reaction is completed, the slag sample is taken out with a quartz tube, and the phosphorus element in the slag is analyzed using an X-ray fluorescence spectrometer (XRF), and the phosphorus content in the molten iron is detected by an I CP-AES inductively coupled plasma atomic emission instrument. Finally, it is found that the P2O5 in the steel slag drops to 0.07wt% under the pulse electric field.

[0050] Table 2.1 Phosphorus content in treated slag (wt%)

[0051]

[0052]

[0053] Table 2.2 Phosphorus content in molten iron after treatment (wt%)

[0054]

[0055] Example 3

[0056] The method and process of recovering phosphorus from steel slag by using pulse electric field in this embodiment are basically the same as those in embodiment 1, except that: in this embodiment, some typical steel slag is mixed and modified with silicon-containing compounds, and the basicity is 1.4, and the specific components are 42.9wt% CaO, 30.65wt% SiO2, 7.2wt% Al2O3, 0.75wt% MgO, 14.5wt% Fe2O3, 2.6wt% P2O5 and a small amount of impurities. The hot molten iron 101 used has a carbon content of 3.5%.

[0057] In this embodiment, low-alkalinity pre-melted steel slag 102 is poured into an electric furnace filled with carbon-containing hot molten iron 101. The experimental temperature is 1450°C, the slag-gold mass ratio is 1:1.8, and the heights of the pre-melted steel slag 102 and the hot molten iron 101 are calculated based on the melt density and the diameter of the electric furnace to be approximately 32.21 cm and 31.93 cm, respectively. Keep warm for 30 minutes to ensure that the pre-melted steel slag 102 melts evenly; then, the cathode 105 is inserted into the pre-melted steel slag 102, and the anode 104 with a corundum tube 103 is inserted into the hot molten iron 101, and the electrode insertion depths are 12 cm, respectively. The extension depths of the cathode 105 and the anode 104 can be raised and lowered by the clamp 106, respectively. A stable pulse electric field is applied externally by a pulse power supply, and the specific waveform is as follows Figure 2 As shown, the frequency of the applied pulse electric field is 500-800Hz, the output voltage is -4.5~4.5V, and the reaction time is 0.45h. After the slag-gold reaction is completed, the slag sample is taken out with a quartz tube, and the phosphorus element in the slag is analyzed using an X-ray fluorescence spectrometer (XRF), and the phosphorus content in the molten iron is detected by an I CP-AES inductively coupled plasma atomic emission instrument. Finally, it is found that the P2O5 in the steel slag drops to 0.11wt% under the pulse electric field.

[0058] Table 3.1 Phosphorus content in treated slag (wt%)

[0059]

[0060] Table 3.2 Phosphorus content in molten iron after treatment (wt%)

[0061]

[0062] Example 4

[0063] The method of recovering phosphorus from steel slag by using a pulse electric field in this embodiment is basically the same as that in Embodiment 1, except that:

[0064] In this embodiment, some typical steel slag is mixed with silicon-containing compounds for modification, with a basicity of 1.6, and specific components of 45.26wt% CaO, 28.29wt% SiO2, 7.2wt% Al2O3, 0.75wt% MgO, 14.5wt% Fe2O3, 2.6wt% P2O5 and a small amount of impurities.

[0065] The carbon content of the carbon-containing molten iron used in this embodiment is 4.5 wt %.

[0066] In this embodiment, low-alkalinity pre-melted steel slag 102 is poured into an electric furnace filled with hot molten iron 101. The experimental temperature is 1450°C, the slag-gold mass ratio is 1:2.0, and the heights of the pre-melted steel slag 102 and the hot molten iron 101 are calculated based on the melt density and the diameter of the electric furnace to be approximately 32.21 and 35.48 cm, respectively. Keep warm for 30 minutes to ensure that the pre-melted steel slag 102 melts evenly; then, the cathode 105 is directly inserted into the pre-melted steel slag 102, and the anode 104 is covered with a corundum tube 103 and inserted into the hot molten iron 101. The electrode insertion depths are 16 cm, and a stable pulse electric field is applied externally through a pulse power supply. The specific waveform is as follows: Figure 2 As shown, the frequency of the applied pulse electric field is 800-1000Hz, the output voltage is -4.5~4.5V, and the reaction time is 0.5h. After the slag-gold reaction is completed, the slag sample is taken out with a quartz tube, and the phosphorus element in the slag is analyzed using an X-ray fluorescence spectrometer (XRF), and the phosphorus content in the molten iron is detected by an ICP-AES inductively coupled plasma atomic emission instrument. Finally, it is found that the P2O5 in the steel slag drops to 0.10wt% under the pulse electric field.

[0067] Table 4.1 Phosphorus content in treated slag (wt%)

[0068]

[0069] Table 4.2 Phosphorus content in molten iron after treatment (wt%)

[0070]

[0071] By comparing the steel slag before and after phosphorus removal, it is found that the pulse electric field method of this embodiment can achieve a maximum phosphorus removal rate of more than 90%, which provides a new method and new idea for simultaneously recovering phosphorus from steel slag.

[0072] The above is a schematic description of the present invention and its implementation mode, which is not restrictive and is only one of the implementation modes of the present invention, and is not actually limited thereto. Therefore, if a person skilled in the art is inspired by it and, without departing from the purpose of the invention, designs a structure and an implementation mode similar to the technical solution without creativity, they shall all fall within the protection scope of the present invention.

Claims

1. A device for recovering phosphorus from steel slag using a pulse electric field, characterized in that: The invention comprises a treatment furnace (100) and an electrode, wherein hot molten iron (101) is contained in the treatment furnace (100), and pre-melted slag (102) is laid on the upper layer of the hot molten iron (101); wherein an anode (104) of the electrode extends downward into the hot molten iron (101), and a cathode (105) of the electrode extends downward into the pre-melted slag (102), and the anode (104) and the cathode (105) are respectively connected to a pulse power supply.

2. The device for recovering phosphorus from steel slag by using a pulse electric field according to claim 1, characterized in that: The anode (104) and the cathode (105) are both extended upward and downward in the treatment furnace (100), and the bottom end of the anode (104) passes through the pre-melted slag (102) and continues to extend downward into the hot molten iron (101); and a corundum tube (103) is provided on the outer periphery of the anode (104), and the corundum tube (103) wraps the area where the anode (104) passes through the pre-melted slag (102).

3. The device for recovering phosphorus from steel slag by using a pulse electric field according to claim 1, characterized in that: The anode (104) is horizontally laid in the hot molten iron (101) at the lower layer of the processing furnace (100), and at least one group of cathodes (105) is vertically extended and distributed in the processing furnace (100), and the bottom end of the cathode (105) extends to the pre-melted slag (102) at the upper layer.

4. A device for recovering phosphorus from steel slag using a pulse electric field according to any one of claims 1 to 3, characterized in that: A protective atmosphere access pipeline is also provided in the treatment furnace (100), and the pipeline extends into the pre-melted slag (102) for conveying the protective atmosphere inward.

5. A method for recovering phosphorus from steel slag using a pulsed electric field, using the device according to any one of claims 1 to 4, characterized in that: The steel slag and silicon-containing solid waste are mixed and pre-melted, and the pre-melted steel slag (102) is poured into a treatment furnace (100) filled with hot molten iron (101), and electrodes are inserted. The anode (104) is inserted into the hot molten iron (101), and the cathode (105) is inserted into the pre-melted steel slag (102). Then, a pulsed electric field of a specific frequency is applied according to different slag alkalinity and carbon content in the molten iron, and the pulsed electric field is maintained for a certain period of time to enhance the effective separation of phosphorus in the steel slag.

6. The method for recovering phosphorus from steel slag by using a pulse electric field according to claim 5, characterized in that: The pulse frequency is controlled as follows: when the carbon content of the molten iron is 0.5-1.5%, and the basicity (CaO / SiO2) of the slag after the steel slag and the silicon-containing solid waste are mixed is 1.0-1.2, the pulse electric field frequency is controlled to be 0-100 Hz, and during the treatment process, the extension depth of the anode (104) in the hot molten iron (101) and the extension depth of the cathode (105) in the pre-melted slag (102) are 4-8 cm, respectively; when the carbon content of the molten iron is 1.5-2.5%, and the basicity (CaO / SiO2) of the slag after the steel slag and the silicon-containing solid waste are mixed is 1.2-1.4, the pulse electric field frequency is controlled to be 100-500 Hz, and during the treatment process, the extension depth of the anode (104) in the hot molten iron (101) and the extension depth of the cathode (105) in the pre-melted slag (102) are 7-10 cm, respectively; when the carbon content of the molten iron is 2.5-3.5%, and the steel slag and the silicon-containing solid waste are mixed is 2.5-3.5%. When the basicity (CaO / SiO2) of the slag after the solid waste is mixed is 1.4-1.6, the pulse electric field frequency is controlled to be 500-800 Hz, and the extension depth of the anode (104) in the hot molten iron (101) and the extension depth of the cathode (105) in the pre-melted steel slag (102) during the treatment process are 12-13 cm respectively; when the carbon content of the molten iron is 3.5-4.5% and the basicity (CaO / SiO2) of the slag after the steel slag and silicon-containing solid waste are mixed is 1.6-1.8, the pulse electric field frequency is controlled to be 800-1000 Hz, and the extension depth of the anode (104) in the hot molten iron (101) and the extension depth of the cathode (105) in the pre-melted steel slag (102) during the treatment process are 16-17 cm respectively.

7. The method for recovering phosphorus from steel slag by using a pulse electric field according to claim 5, characterized in that: During the treatment process, the extension length of the anode (104) and the cathode (105) in the melt is 1 / 4-1 / 2 of the melt depth.

8. The method for recovering phosphorus from steel slag by using a pulse electric field according to claim 5, characterized in that: In the treatment furnace (100), the mass ratio of the pre-melted slag (102) to the hot molten iron (101) is 1:1-2.0, and an electric field reaction is applied at a high temperature of 1400-1450°C for 0.15-0.5h.

9. The method for recovering phosphorus from steel slag by using a pulse electric field according to claim 5, characterized in that: The voltage of the applied pulse electric field is -4.5-4.5V, in which the forward voltage accounts for 70-90% of one pulse cycle, no voltage accounts for 10%, and the reverse voltage accounts for 0-20%.

10. The method for recovering phosphorus from steel slag by using a pulse electric field according to claim 5, characterized in that: The anode (104) and the cathode (105) are respectively connected to a pulse power supply through a clamp (106) and corresponding wires, the wires are made of copper wires, and the clamp (106) is made of stainless steel; the anode (104) and the cathode (105) are both rod-shaped electrodes, and the material is graphite.

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