Method for strengthening steel slag and simultaneously recovering iron and phosphorus by utilizing direct-current electric field

Abstract

The invention discloses a method for strengthening steel slag and simultaneously recovering iron and phosphorus by utilizing a direct-current electric field, and belongs to the field of steel slag treatment. The method comprises the following steps: alkali reduction and modification of the steel slag: uniformly mixing the steel slag and a siliceous modifier at 1400 DEG C or above to ensure the fluidity of the steel slag; preliminary reduction and recovery: mixing the modified steel slag with high-carbon hot molten iron, and preliminarily reducing iron and phosphorus in the steel slag through the reduction effect of the high-carbon molten iron; and deep reduction recovery is conducted, the redox reaction between slag and gold is further strengthened through electric field strengthening, volatilization of phosphorus is reduced, and iron and phosphorus in the steel slag are further recovered through the promoting effect of the electric field. The invention aims to solve the problems of efficient treatment of the phosphorus-containing steel slag and simultaneous recovery of the valuable element phosphorus in the steel slag, the phosphorus removal rate is high, the speed is high, the cost is low, the low-phosphorus steel slag and the phosphorus-containing molten steel can be reused, and the economic benefits of enterprises are improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel slag treatment, and more specifically to a method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag. 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 grade of steel continues to improve, the amount of slag emissions is also increasing. Under the dual pressures of environmental pollution and waste of resources, the issue of rational utilization of slag needs to be urgently addressed.

[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, the related patent documents of the technology of dephosphorization of steel slag are disclosed, such as Chinese Patent Publication No.: CN110184399A, which discloses a steel slag treatment method adopting oxidation desulfurization and reduction dephosphorization two-step method, wherein the steel slag adopting oxidation desulfurization and reduction dephosphorization two-step method, a mixed gas of Ar and O2 is introduced into the molten steel slag, SO2 obtained by oxidation overflows from the slag phase and is removed, and then a mixed gas of CO and CO2 is introduced, and the phosphorus removal rate reaches more than 80%, but this method is easy to cause environmental pollution and cause phosphorus resource waste, and the process is also relatively complicated. Chinese Patent Publication No.: CN110129492A, which discloses a method for treating steel slag, wherein liquid converter steel slag is reduced and treated by slag splashing furnace protection operation, and then the molten iron obtained by reduction is desulfurized and / or desiliconized and / or dephosphorized, and the obtained slag is cooled by water to obtain filtrate and filter residue, and then smelted and recovered after drying, and this process is very complicated. Chinese Patent Publication No.: CN110526745A discloses a method for separating phosphorus from dephosphorized steel slag and preparing phosphate fertilizer, wherein the dephosphorized steel slag is selectively leached in an aqueous solution to obtain a low-phosphorus residue and a phosphorus-containing leachate; then, by adding an alkaline substance to the phosphorus-containing leachate to increase the pH value of the leachate, the phosphorus in the leachate forms a calcium phosphate precipitate, which is used as a phosphate fertilizer, and the low-phosphorus residue is used in sintering or steelmaking, but a large amount of slag waste heat is wasted by selective leaching, and the process is very complicated. Chinese Patent Publication No.: CN116426700A discloses a method for extracting phosphorus from steel slag and a method for producing a phosphorus-containing compound fertilizer for seaweed nutrient solution, wherein the solid steel slag is acid-leached with a citric acid solution, and the filtrate is used as a phosphorus-iron compound fertilizer for the production of seaweed nutrient solution, but it also faces problems such as waste heat loss, long leaching time, and complex process. Chinese Patent Publication No.: CN117721256A discloses a system and method for high-temperature steel slag molten state efficient treatment and full resource utilization, and studies a dephosphorization device for dephosphorization of reduced iron water produced by smelting, but the reduction method is easy to cause phosphorus volatilization and the dephosphorization speed is slow. Chinese Patent Publication No. CN114472464A discloses a method for efficiently recovering iron and phosphorus resources in phosphorus-containing steel slag, by modifying the phosphorus-containing steel slag, and then using heat treatment to selectively grow the magnetic Fe3O4 phase and the calcium phosphate phase, but this method still needs further flotation separation to recover phosphorus resources, and the magnetic separation and heat treatment time are long, which is not conducive to large-scale industrial application. Chinese Patent Publication No. CN115896363A and CN109207658A respectively disclose methods for promoting phosphorus recovery by modifying steel slag with biomass ash and coffee grounds, but the operation is complicated, the leaching time is long, the waste heat is wasted, the utilization value is low, and it cannot fully meet the requirements of large-scale recycling of steel slag. Summary of the invention

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

[0006] In order to solve the problem of difficulty in recycling steel slag in the prior art, the present invention intends to provide a method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the recovery of Fe and P from steel slag. The electric field is used to promote the enhanced recovery of Fe and P from steel slag. Not only is the phosphorus removal rate high, the speed fast, and the cost low, but the iron in the steel slag can also be recovered at the same time. The produced phosphorus-containing molten steel is convenient for subsequent reuse, thereby greatly improving the 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 method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag, comprising:

[0010] S1. Alkali reduction and modification of steel slag: Mix the steel slag and silicon modifier evenly to ensure the fluidity of the steel slag;

[0011] Specifically, in S1, a certain proportion of siliceous modifier is prepared according to the original basicity of the steel slag to be treated, and low-basicity modified steel slag is obtained by stirring and mixing, so as to ensure that the steel slag has high fluidity during the reaction at high temperature and avoid slag drying;

[0012] Preferably, the steel slag and the siliceous modifier in S1 are mixed and uniformly modified at a temperature of 1400°C-1450°C. In practice, 1400°C, 1420°C, 1430°C, 1450°C, etc. may be used;

[0013] Furthermore, the modified basicity of the mixed modified steel slag (CaO / SiO2) is 1.0-1.5, and the target viscosity of the steel slag is below 0.25 Pa·s to avoid poor fluidity and drying of the steel slag during the reduction process; in practice, the siliceous modifier can be SiO2, silicon-containing compounds, etc.;

[0014] Preferably, the modified steel slag in step S1 comprises the following components in percentage by mass: 31.5-42.6 wt% CaO, 28.4-31.5 wt% SiO2, 2-4 wt% Al2O3, 4-6 wt% MgO, 20-25 wt% Fe2O3, 1-4 wt% P2O5 and unavoidable impurities;

[0015] S2. Preliminary reduction and recovery: the modified steel slag is mixed with high-carbon hot molten iron, and the iron and phosphorus in the steel slag are preliminarily reduced by the reduction effect of the high-carbon hot molten iron;

[0016] Preferably, in S2, the low-basicity modified steel slag and high-carbon molten iron are mixed in a specific ratio of 1:1-2, melted at a temperature of 1400-1450°C, and maintained for 0.15-0.5h to complete the reaction; in practice, the ratio of modified steel slag to high-carbon molten iron can be 1:1, 1:1.5, 1:2, etc., the reaction temperature can be 1400°C, 1420°C, 1450°C, etc., and the reaction time can be 0.15h, 0.2h, 0.35h, 0.5h, etc.; the high-temperature reducibility of carbon element is used to partially reduce and recover the iron and phosphorus elements in the steel slag, and P2O5 in the steel slag is mainly obtained by directional reduction of carbon element 3- ; Among them, high carbon molten iron has a certain reducibility, and the higher the proportion, the more conducive it is to the recovery of phosphorus in steel slag;

[0017] Preferably, the carbon content of the high carbon molten iron used in S2 is 2wt% to 5wt%; in practice, the carbon content may be 2wt%, 3wt%, 4wt%, 5wt%, etc.;

[0018] Initial reduction recovery is to use the reduction effect of high-carbon molten iron to recover phosphorus and iron in steel slag. However, in practice, it is not possible to make the phosphorus and iron in steel slag reach the target level in a short time, and the reaction speed is relatively slow.

[0019] S3. Deep reduction recovery: The redox reaction between slag and metal is further enhanced by electric field strengthening, the volatilization of phosphorus is reduced, the iron and phosphorus in the slag are recovered by the promotion of the electric field, and the migration of iron and phosphorus elements from the slag to the molten iron interface is driven to further improve the recovery rate of iron and phosphorus.

[0020] In practice, it is preferred that the DC voltage U applied in S3 is 2 to 4V, the output current I is 0.4 to 0.6A, the electrode for applying the electric field is graphite, the electrode application method is that the slag is the cathode and the molten iron is the positive electrode, and the reaction time is preferably 0.15 to 0.5h; in practice, the voltage U can be 2V, 3V, 4V, etc., the output current I can be 0.4A, 0.5A, 0.6A, etc., and the reaction time can be 0.15h, 0.35h, 0.5h, etc.; the main reduction reactions are as follows (1) and (2): First, P2O5 in the slag is reduced to P by carbon-saturated molten iron 2(g) , then P 2(g) Under the action of electric field, it is further reduced to generate P 3- , and then enters the molten iron under the action of the electric field force, thereby inhibiting the volatilization of phosphorus and improving the recovery rate of phosphorus.

[0021] P 2(g) +(O 2- )+CO= 2(P 3- )+CO 2(g) (1)

[0022] (P 3- )-3e- = [P] (2)

[0023] Steel slag can be recovered by electric field strengthening after steelmaking slag is discharged, and the waste heat of slag is fully utilized to reduce P2O5 in steel slag to obtain P2O5 by carbon in molten iron. 3- , and then migrate into the molten iron through the electric field force, reducing P 2(g) The phosphorus-containing molten steel obtained by volatilization is used for smelting phosphorus-containing alloys or as a raw material for high-grade ferrophosphorus production for resource storage, avoiding the waste of phosphorus resources; the dephosphorization speed of steel slag is fast, and the iron in the steel slag can be recovered at the same time. The phosphorus and iron contents in the waste slag can be reduced to the target level within 0.15 to 0.5 hours, and the phosphorus mobility can reach more than 90%.

[0024] In practice, the low-phosphorus slag obtained in step S3 can be directly returned to steelmaking production as a steel slag dephosphorization agent; the obtained molten steel is used for smelting phosphorus-containing alloys or as a raw material for high-grade ferrophosphorus production for resource storage.

[0025] The electric field enhancement method used in the present invention is a new process developed based on the steel slag reduction method. Compared with other methods, it has the advantages of environmental protection, economy and high efficiency. First, the addition of silicon modifier is to reduce the basicity of steel slag and its target viscosity. In the process of dissolving carbon reduction in carbon-saturated molten iron, the slag still has good fluidity and electric field directional migration conditions. Secondly, under the action of DC voltage, PO4 3- Restored to P 3- The silicon modifier is used as a modifier to reduce the viscosity and melting point of the steel slag and avoid drying out during the reduction process of the steel slag, and then a certain DC electric field is applied to further improve the recovery rate of phosphorus in the steel slag, reduce the volatilization of phosphorus during the reduction process, realize the directional migration of phosphorus, and simultaneously realize the recovery of iron in the steel slag, thereby obtaining low-phosphorus steel slag and phosphorus-containing molten steel, killing two birds with one stone.

[0026] 3. Beneficial effects

[0027] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0028] (1) At present, most of the solid waste treatment methods only consider the reaction of the waste slag itself or direct external circulation, ignoring that phosphorus resources as a strategic resource are constantly decreasing. There are also relatively few studies on how to collect phosphorus and iron resources in steel slag in a targeted manner. The present invention applies a certain voltage to the steel slag to enhance the redox reaction between slag and metal through the electric field to remove the phosphorus content in the waste slag. The operation is simpler, the time is shorter, and it is more environmentally friendly and efficient. It realizes the simultaneous recovery and utilization of phosphorus and iron resources, and greatly improves the utilization value of steel slag.

[0029] (2) The present invention provides a method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag. A direct current power supply applies an electric field at a high temperature to provide a driving force for phosphorus, thereby accelerating the redox reaction of the steel slag. The maximum removal rate of phosphorus in the steel slag can reach more than 85%. By applying a certain electric field to react with high-carbon molten iron to produce slag, phosphorus in the steel slag can be efficiently removed. This solves the limiting link of low phosphorus removal rate in steel slag, obtains phosphorus-containing molten steel, inhibits phosphorus volatilization, and improves the utilization value of phosphorus. The operation is also relatively simple and the time is relatively short.

[0030] (3) The present invention discloses a method for simultaneously recovering iron and phosphorus by utilizing direct current electric field to strengthen steel slag. The method utilizes the ion migration during the redox reaction of the slag-metal reaction between the molten slag and the melt to strengthen the electric field. In actual production, it is only necessary to add a certain proportion of high-carbon molten iron into the slag pot in advance, and then add a silicon modifier to the high-phosphorus steel slag (the slag temperature can reach above 1600°C during the slag-discharging stage of steelmaking) to control the basicity within the range of 1.0 to 1.5, and then pour it into the slag pot at a slag-metal ratio of 1: (1 to 2). The phosphorus is enriched in the molten iron by the electric field to strengthen the slag-metal reaction. After the reaction is continued for 0.15 to 0.5 hours, a low-phosphorus steel slag that meets the requirements of steelmaking production can be obtained.

[0031] (4) The present invention provides a method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening. The alkalinity in the steel slag is controlled within the range of 1.0 to 1.5 by means of a modifier. The target viscosity of the steel slag is rapidly reduced to below 0.25 Pa.s. This can effectively prevent the steel slag from drying out during the reduction reaction, increase the fluidity of the slag, and is also beneficial to the electric field strengthening of the directional migration of phosphorus ions in the waste slag to the molten iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag. DETAILED DESCRIPTION

[0033] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings.

[0034] 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.

[0035] The present invention will be further described below in conjunction with the embodiments.

[0036] Example 1

[0037] A method for simultaneously recovering iron and phosphorus from steel slag by using a direct current electric field to strengthen the steel slag of this embodiment includes the following steps:

[0038] S1. Alkali reduction and modification of steel slag. The steel slag and the silicon modifier are uniformly mixed at a certain mass ratio at 1400° C. so that the alkalinity of the mixed and modified mixture is 1.0. Adding the silicon modifier to the slag is conducive to simplifying the slag structure, reducing the viscosity, preventing the slag from drying out after reduction, increasing the liquid phase volume, and significantly improving the dephosphorization reduction kinetic conditions; the modified mixture includes the following mass percentage components: 31.50wt% CaO, 31.50wt% SiO2, 4.0wt% Al2O3, 4.0wt% MgO, 25wt% Fe2O3, 4wt% P2O5, and a small amount of impurities;

[0039] S2. Preliminary reduction and recovery: the modified steel slag is mixed with high-carbon hot iron in a ratio of 1:2, melted at 1400°C and kept for 0.5h, and the iron and phosphorus in the steel slag are preliminarily reduced by the reduction effect of the high-carbon hot iron; the carbon content in the high-carbon hot iron is 2wt%;

[0040] S3, deep reduction recovery: further strengthen the slag-metal redox reaction through electric field strengthening, reduce the volatilization of phosphorus, and recover iron and phosphorus in steel slag through the promotion of electric field;

[0041] Specifically, after high-temperature modification of steel slag, pour it into a corundum crucible filled with hot molten iron, finally, the cathode is directly inserted into the slag through an electrode lifting device, and the anode outer shell corundum sleeve is inserted into the molten iron, and a stable electric field is applied externally through a DC stabilized power supply, and the output voltage U of the external DC power supply is applied. The applied voltages are 0V, 2V, 3V and 4V respectively, and the output current I is 0.4-0.6A. The reaction is 0.15h, and the slag is the negative electrode and the molten iron is the positive electrode. After the slag gold reaction is completed, a quartz tube is used to take out a slag sample, and an X-ray fluorescence spectrometer (XRF) is used to analyze the phosphorus element in the slag. The ICP-AES inductively coupled plasma atomic emission instrument detects the phosphorus content in the molten iron. Finally, it is found that the phosphorus content in the steel slag at a voltage of 4V decreases from 1.1wt% to 0.26wt%, and the phosphorus removal rate is much higher than that without applying an electric field. After applying an electric field, the iron content in the slag is also reduced to 1.4wt%, and the phosphorus content in the molten iron increases to 0.42wt%, and the electric field can significantly inhibit the volatilization of phosphorus. In practice, the component contents of high carbon molten iron are shown in Table 1.1 below, the contents of iron and phosphorus in the slag after treatment by the method of this embodiment are shown in Table 1.2 below, and the phosphorus content in the molten iron in the slag after treatment is shown in Table 1.3 below.

[0042] Table 1.1 High carbon hot metal component content (wt%)

[0043] Hot metal composition Fe Mn C Si P S content 99.9 0.02 2.0 0.02 0.01 0.008

[0044] Table 1.2 Iron and phosphorus content in treated slag (wt%)

[0045]

[0046]

[0047] Table 1.3 Phosphorus content in molten iron after treatment (wt%)

[0048]

[0049] In this embodiment, an electric field is used to promote the redox reaction of iron and phosphorus in steel slag, and the electric field can effectively inhibit the volatilization of phosphorus in the slag, harvest low-phosphorus slag that meets the conditions, and obtain low-phosphorus slag and phosphorus-containing molten iron. The hot low-phosphorus slag is recycled as a steel slag dephosphorizer or steelmaking slag-making agent, and the phosphorus-containing molten steel is used for phosphorus-containing alloy smelting or as a high-grade ferrophosphorus production raw material for resource storage.

[0050] This embodiment simulates the process of treating steel slag in a high-temperature electric field during production. In actual production, it is only necessary to add a certain proportion of high-carbon molten iron to the slag pot in advance, and then modify the steel slag with high phosphorus content through a silicon modifier to reduce the basicity of the steel slag, avoid the steel slag from drying out during the reduction process, and obtain excellent performance that is conducive to electric field phosphorus removal. Then, hot steel slag with low phosphorus content can be obtained through electric field strengthening, and this part of low-phosphorus slag can be directly returned to steelmaking production.

[0051] At present, most methods for treating steel slag have the problems of wasting phosphorus resources, wasting slag waste heat, complicated operation and long treatment time. The method of this embodiment directly uses the electric field to strengthen the redox reaction between slag and metal, provides a condition conducive to the reduction of P2O5, and then promotes the reduction of P2O5 through the electric field force. 3- Directed migration into molten iron is simple to operate, highly efficient, and more environmentally friendly. It avoids the waste of phosphorus resources to a certain extent and improves the utilization value of steel slag.

[0052] Example 2

[0053] The method of simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag in this embodiment is basically the same as that in embodiment 1, except that:

[0054] In step S1, steel slag and siliceous modifier are mixed uniformly at 1425° C. The modified mixture includes the following components in mass percentage: 37.1wt% CaO, 30.90wt% SiO2, 3.0wt% Al2O3, 5.0wt% MgO, 25wt% Fe2O3, 2wt% P2O5, and a small amount of impurities. The basicity of the modified steel slag is 1.2;

[0055] In step S2, the modified steel slag and high carbon hot molten iron are mixed in a ratio of 1:1.5, melted at 1425°C and kept for 0.5h, and the carbon content in the high carbon molten iron is 3wt%;

[0056] In step S3, the cathode is directly inserted into the slag through the electrode lifting device, the anode outer shell corundum sleeve is inserted into the molten iron, and a stable electric field is applied externally through a DC stabilized power supply, and the output voltage U of the external DC power supply is U=2~4V, and the output current I is 0.4~0.6A, and the reaction is 0.25h. After the slag gold reaction is completed, a quartz tube is used to take out a slag sample, and an X-ray fluorescence spectrometer (XRF) is used to analyze the phosphorus element in the slag, and an ICP-AES inductively coupled plasma atomic emission instrument is used to detect the phosphorus content in the molten iron. Finally, it is found that the phosphorus content in the steel slag at 4V voltage decreases from 0.6wt% to 0.08wt%, and the phosphorus removal rate is much higher than that without applying an electric field. After applying an electric field, the iron content in the slag is also reduced to 0.07wt%, and the phosphorus content in the molten iron increases to 0.34wt%, and the electric field can significantly inhibit the volatilization of phosphorus. In practice, the component contents of high carbon molten iron are shown in Table 2.1 below, the contents of iron and phosphorus in the slag after treatment by the method of this embodiment are shown in Table 2.2 below, and the phosphorus content in the molten iron in the slag after treatment is shown in Table 2.3 below.

[0057] Table 2.1 High carbon hot metal component content (wt%)

[0058] Hot metal composition Fe Mn C Si P S content 99.9 0.02 3.0 0.02 0.01 0.008

[0059] Table 2.2 Phosphorus and iron content in treated slag (wt%)

[0060]

[0061] Table 2.3 Phosphorus content in molten iron after treatment (wt%)

[0062]

[0063] Example 3

[0064] The new method for simultaneously recovering iron and phosphorus by strengthening steel slag with a direct current electric field in this embodiment has the same basic steps as those in Example 1, except that in this embodiment:

[0065] In step S1, steel slag and siliceous modifier are mixed uniformly at 1450° C., and the modified mixture includes the following components in mass percentage: 42.6wt% CaO, 28.4wt% SiO2, 2.0wt% Al2O3, 6.0wt% MgO, 20wt% Fe2O3, 1wt% P2O5, and a small amount of impurities. The basicity of the modified steel slag is 1.5;

[0066] In step S2, the modified steel slag and high-carbon hot iron are mixed in a ratio of 1:1, melted at 1450° C. and maintained for 0.5 h, and the carbon content in the high-carbon hot iron is 5 wt%;

[0067] In step S3, the cathode is directly inserted into the slag through the electrode lifting device, the anode outer shell corundum sleeve is inserted into the molten iron, and a stable electric field is applied externally through a DC stabilized power supply, and the output voltage U of the external DC power supply is U=2~4V, and the output current I is 0.4~0.6A, and the reaction is 0.5h. After the slag gold reaction is completed, a quartz tube is used to take out a slag sample, and an X-ray fluorescence spectrometer (XRF) is used to analyze the phosphorus element in the slag, and an ICP-AES inductively coupled plasma atomic emission instrument is used to detect the phosphorus content in the molten iron. Finally, it is found that the phosphorus content in the steel slag at a voltage of 4V decreases from 0.30wt% to 0.08wt%, and the phosphorus removal rate is much higher than that without applying an electric field. After applying an electric field, the iron content in the slag is also reduced to 3.2wt%, and the phosphorus content in the molten iron increases to 0.21wt%, and the electric field can significantly inhibit the volatilization of phosphorus.

[0068] In practice, the component contents of high carbon molten iron are shown in Table 3.1 below, the contents of iron and phosphorus in the slag after treatment by the method of this embodiment are shown in Table 3.2 below, and the phosphorus content in the molten iron in the slag after treatment is shown in Table 3.3 below.

[0069] Table 3.1 High carbon hot metal component content (wt%)

[0070] Hot metal composition Fe Mn C Si P S content 99.9 0.02 5.0 0.02 0.01 0.008

[0071] Table 3.2 Phosphorus and iron content in treated slag (wt%)

[0072]

[0073] Table 3.3 Phosphorus content in molten iron after treatment (wt%)

[0074]

[0075] By comparing the slag before and after phosphorus removal and iron removal, when the alkalinity is between 1.0 and 1.5, it is found that the maximum phosphorus removal rate of the method of this embodiment can reach more than 86%, the iron content in the slag is further reduced with the application of 0 to 4V voltage, the phosphorus content in the molten iron continues to increase, the electric field inhibits the volatilization of phosphorus, and the phosphorus content in the molten iron reaches a maximum of 0.42wt%. In addition, the operation is simple in actual enterprise applications, which provides a new method and new idea for the simultaneous recovery of phosphorus and iron from slag.

[0076] 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 method for simultaneously recovering iron and phosphorus from steel slag by utilizing a direct current electric field to strengthen the steel slag, characterized in that: include: S1. Alkali reduction and modification of steel slag: Mix the steel slag and silicon modifier evenly to ensure the fluidity of the steel slag; S2. Preliminary reduction and recovery: the modified steel slag is mixed with high-carbon hot molten iron, and the iron and phosphorus in the steel slag are preliminarily reduced by the reduction effect of the high-carbon hot molten iron; S3. Deep reduction recovery: The redox reaction between slag and metal is further enhanced by electric field strengthening, the volatilization of phosphorus is reduced, and the iron and phosphorus in the steel slag are recovered by the promotion of the electric field.

2. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 1, characterized in that: The basicity of the steel slag after mixing and modification in step S1 is 1.0 to 1.

5.

3. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 2, characterized in that: The target viscosity of the mixed and modified steel slag in step S1 is reduced to below 0.25 Pa.s.

4. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 1, characterized in that: In step S1, the steel slag and the siliceous modifier are mixed and uniformly modified at a temperature of 1400°C-1450°C.

5. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 1, characterized in that: In step S2, the modified steel slag and hot high-carbon molten iron are mixed in a mass ratio of 1:1 to 2.

6. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 5, characterized in that: In step S2, the modified steel slag is mixed with hot high-carbon molten iron and reacted at a temperature of 1400-1450° C. for 0.15-0.5 h.

7. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 5 or 6, characterized in that: The carbon content of the high carbon molten iron used in step S2 is 2wt% to 5wt%.

8. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to any one of claims 1 to 6, characterized in that: In step S3, the applied DC voltage U is 2-4V, and the output current I is 0.4-0.6A.

9. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to claim 8, characterized in that: In step S3, the electrode for applying the electric field is graphite, and the electrode is applied in a manner that the slag is the cathode and the molten iron is the positive electrode.

10. The method for simultaneously recovering iron and phosphorus from steel slag by utilizing direct current electric field strengthening according to any one of claims 1 to 4, characterized in that: The modified steel slag in step S1 includes the following components in mass percentage: 31.5-42.6wt% CaO, 28.4-31.5wt% SiO2, 2-4wt% Al2O3, 4-6wt% MgO, 20-25wt% Fe2O3, 1-4wt% P2O5 and inevitable impurities.

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