Method for refining ferrophosphorus by blowing carbon dioxide

Abstract

The invention relates to a method for refining ferrophosphorus by blowing carbon dioxide, which comprises the steps of raw material preparation, melting, carbon dioxide blowing refining and the like, and specifically comprises the following steps: blowing and refining ferrophosphorus by setting carbon dioxide, setting a slag former, and synergistically matching various parameters such as carbon dioxide blowing flow, blowing time, refining temperature and the like. Fixed-point removal of various impurities in ferrophosphorus in an accurate thermodynamic reaction interval is achieved, and meanwhile low loss of the phosphorus content in ferrophosphorus is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of metal smelting and raw material preparation, and in particular to a method for refining ferrophosphorus by injecting carbon dioxide. Background Art

[0002] Ordinary ferrophosphorus is crude ferrophosphorus, which contains more impurities such as titanium, manganese, vanadium, etc. The prior art generally refines ordinary ferrophosphorus to obtain refined ferrophosphorus for use. The process of ferrophosphorus refining is mainly to remove impurities therein through refining. At present, induction furnace is mainly used for refining. The principle of induction furnace is to use the induction electrothermal effect of the material to heat or melt the material. Under the action of the alternating electromagnetic field in the induction furnace, eddy currents are generated inside the material to achieve the effect of heating or melting. The prior art generally removes impurities by adding solid oxidants during the heating process. However, although the existing solid oxidants can achieve the removal of some impurity elements in ferrophosphorus, for elements with low impurity content (such as V), if the impurity elements are to be deeply removed, it is necessary to add excessive solid oxidants. This process will seriously increase the refining pressure and reduce the processing capacity of the smelting.

[0003] In the process of alloy smelting, gas injection is carried out to the melt to achieve the purpose of oxidation or reduction. It is a prior art in the metal smelting process, and the most conventional one is the converter steelmaking with oxygen injection. There is also a prior art of injecting oxygen to oxidize the melt in the smelting process of ferromanganese. The Chinese invention patent announcement text CN1057134C discloses a production method of medium and low carbon ferromanganese, that is, discloses a method of smelting ferromanganese by injecting oxygen to increase the manganese content. The Chinese invention patent announcement text CN114574641B also discloses a method for smelting medium-low carbon ferromanganese, which is obtained by smelting high carbon ferromanganese in a converter by mixed injection of carbon dioxide and oxygen. Since ferromanganese is mainly to remove carbon, and the refining of ferrophosphorus is not mainly to remove carbon, these smelting methods of injecting gas are not applied to the refining of ferrophosphorus. Chinese invention patent publication CN112095043A discloses a method for removing titanium from a high-titanium ferrophosphorus alloy, which involves introducing carbon dioxide gas into the alloy in a solid state for pretreatment to form surface slag, then melting the alloy normally, and using the surface slag to remove titanium. The carbon dioxide involved is a solid-gas reaction, and is only used for pretreatment to form slag, and does not involve the removal of impurities in the alloy by carbon dioxide. Summary of the invention

[0004] In order to solve the above technical problems and achieve the purpose of accurate removal of all impurity elements in the refining process of ferrophosphorus, deep removal and improved processing capacity, this patent sets up a carbon dioxide blowing method through thermodynamic analysis to complete the refining of ferrophosphorus.

[0005] This is achieved through the following technical means:

[0006] A method for refining ferrophosphorus by injecting carbon dioxide comprises the following steps:

[0007] (1) Raw material preparation: 80-130 parts by weight of blocky common ferrophosphorus with a particle size or equivalent particle size greater than 50 cm; 9-12 parts by weight of a slag-forming agent with a particle size or equivalent particle size of 10-20 cm; the slag-forming agent is limestone, silica and dolomite mixed in a weight ratio of (4-6): (1.5-2.6): (2.6-3.5).

[0008] (2) Melting: placing the common ferrophosphorus obtained in step (1) into an induction furnace for melting, heating the temperature to 1300-1450° C., maintaining the temperature for 30-40 min until the common ferrophosphorus is completely melted, adding the slag-forming agent obtained in step (1), and then continuously heating the temperature to 1490-1520° C., maintaining the temperature for 15-20 min until the slag-forming agent is completely melted, then powering off the induction furnace, stopping heating, and powering on the induction furnace again after the melt naturally cools to 1150-1450° C. and maintaining the temperature;

[0009] (3) Carbon dioxide blowing refining, wherein carbon dioxide gas is blown onto the surface of the melt obtained by naturally cooling to 1150-1450° C. in step (2) by an oxygen lance in a top blowing manner, wherein the distance between the nozzle of the oxygen lance and the melt surface is 30-50 cm, the Mach number M at the nozzle outlet of the oxygen lance is 1.7-2.2, and the carbon dioxide gas blowing time is 30-50 min. During the blowing process, the melt is heated by an induction furnace to maintain the melt temperature at 1150-1450° C. After the blowing is completed, the temperature is raised to 1530-1600° C., and then the ferrophosphorus and slag in the induction furnace are cast into a mold together and allowed to stand until the temperature drops to room temperature, and the upper slag and the lower ferrophosphorus are separated, and the upper slag is separated and removed to obtain refined ferrophosphorus.

[0010] Preferably, in step (3), the oxygen lance sprays carbon dioxide in an intermittent cyclic manner, wherein after each carbon dioxide spray of 4 to 6 minutes, the spraying is stopped for 30 to 60 seconds, and then the spraying is continued, repeating the cycle.

[0011] Preferably, the contents of each element in the ferrophosphorus in step (1) are as follows by mass percentage: P: 22-25wt.%; Ti: 1.14-2.01wt.%; Mn: 2.19-3.18wt.%, V: 1.5-2.3wt.%, and the remainder is Fe and unavoidable impurities.

[0012] Preferably, in the limestone in step (1), the mass percentage content of CaCO3 is greater than 97wt.%, and the rest are unavoidable impurities; the mass percentage content of SiO2 in silica is greater than 98wt.%, and the rest are unavoidable impurities; the total mass percentage content of CaCO3 and MgCO3 in dolomite is greater than 95wt.%, and the rest are unavoidable impurities.

[0013] Preferably, the weight ratio of the slag-forming agent is limestone:silica:dolomite=5:2:3.

[0014] Preferably, the induction furnace described in step (2) is a medium frequency induction furnace.

[0015] Preferably, the weight ratio of ordinary ferrophosphorus to slag-forming agent in step (1) is (90-120):10.

[0016] Preferably, the carbon dioxide gas in step (3) is industrial carbon dioxide gas, and the oxygen lance is used to spray carbon dioxide in an intermittent cycle. After each carbon dioxide spray for 5 minutes, the spraying is stopped for 45 seconds, and then the spraying is continued in this cycle.

[0017] Preferably, the contents of each element in the refined ferrophosphorus obtained in step (3) are as follows by mass percentage: P: 21-26wt.%; Ti: 0.05-0.07wt.%; Mn: 0.58-0.75wt.%, V: 0.68-0.91wt.%, and the remainder is Fe and unavoidable impurities.

[0018] Preferably, in step (1), 80 to 130 parts by weight of blocky common ferrophosphorus having a particle size or an equivalent particle size greater than 50 cm and less than 100 cm is prepared.

[0019] The common ferrophosphorus used as raw material in the present invention is commercially available crude ferrophosphorus. The oxygen gun and carbon dioxide gas are both commercially available devices or materials.

[0020] The technical effects of the present invention are:

[0021] 1. The research team of the present invention has conducted in-depth research on the relationship between the Gibbs free energy of various impurities and carbon in ferrophosphorus alloys and temperature, as well as the relationship between them. Figure 1As shown, the analysis shows that at a specific temperature (1000-1400°C), carbon dioxide can remove impurity elements such as Ti, Mn, and V, and does not react with the phosphorus element in ferrophosphorus, thereby ensuring the stability of the phosphorus content. Therefore, a creative technical idea of ​​using oxygen lance blowing to replace the existing solid oxidant in the ferrophosphorus refining process is proposed. Through in-depth research, various parameters such as the distance between liquid levels, outlet Mach number, blowing time, intermittent cyclic blowing, blowing temperature, and slag-forming agent formulation are strictly controlled during the carbon dioxide blowing process, thereby achieving the technical effect of replacing solid oxidants with low-cost and efficient carbon dioxide gas blowing, high processing pressure, and reduced raw material costs.

[0022] 2. The present invention not only simply uses carbon dioxide injection to replace solid oxidants, but also specifically defines the carbon dioxide injection method, various parameters and control indicators. These parameters are closely coordinated with each other. The change of any parameter does not simply change the effect with the change of the parameter, but the overall impurity removal effect has a large change. In particular, the intermittent cyclic injection of carbon dioxide is creatively proposed. During the injection period, it is ensured that the carbon dioxide gas flow sprayed from the oxygen gun can stir the melt, so that the carbon dioxide and the melt are in full contact. During the period of stopping the injection, the oxides generated in it are combined with the slag on the surface of the melt to form slag, avoiding the whole injection process. The oxide cannot be combined with the slag and re-enters the melt and returns to the metal phase. This setting not only ensures the injection time and improves the efficiency, but also reduces the use of carbon dioxide and saves costs.

[0023] 3. The present invention sprays carbon dioxide under specific melt temperature conditions, which, to a certain extent, ensures the removal effect while reducing the volatilization of phosphorus, so that the phosphorus content in the raw material common ferrophosphorus and the product refined ferrophosphorus remains basically unchanged, ensuring the quality of the final product. At the same time, the present invention uses blocky common ferrophosphorus with a particle size or equivalent particle size greater than 50 cm as the raw material, which can greatly shorten the melting and heat preservation time and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a curve showing the variation of Gibbs free energy of the removal reaction of various impurity elements in ferrophosphorus with temperature. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Reference to "embodiments" herein means that a particular feature, step, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] The present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] The batching and refining method of the refined ferrophosphorus of this embodiment was carried out in a ferroalloy plant in Henan Province, and included the following steps:

[0030] (1) Ingredients: select ordinary ferrophosphorus with a particle size greater than 50 cm, the amount of ferrophosphorus is 300 kg, and fill it into a 0.5 t medium frequency induction furnace for smelting. The content of each element in the ferrophosphorus is calculated by mass percentage as follows: P: 23.20wt.%; Ti: 1.23wt.%; Mn: 2.65wt.%, V: 2.03wt.%, and the remainder is Fe and unavoidable impurities. Prepare slag-making agent, which is limestone, silica and dolomite mixed in a weight ratio of 5:2:3.

[0031] (2) Melting: After the ferrophosphorus added to the medium frequency induction furnace in step (1) is completely melted, 30 kg of the slag-forming agent prepared in step (1) is added, the temperature is raised to 1500 degrees Celsius, and the temperature is kept for 20 minutes to completely melt the slag phase. After the slag phase is melted, the temperature is naturally reduced to 1300-1400 degrees Celsius.

[0032] (3) blowing and refining, the molten slag phase and iron phase in step (2) are subjected to carbon dioxide blowing refining, the carbon dioxide gas is blown by an oxygen lance, and the oxygen lance is 40 cm away from the melt surface; the Mach number M of the oxygen lance nozzle outlet is 2.0, the blowing time is 40 min, and the carbon dioxide is blown by the oxygen lance in an intermittent cycle. After each carbon dioxide blow for 5 min, the blowing is stopped for 45 s, and then the blowing is continued in this cycle. During the blowing process, the melt is supplemented with heat by an induction furnace to maintain the melt temperature at 1300-1450°C. After the blowing time is over, the ferrophosphorus phase and the slag phase are poured out, and refined ferrophosphorus is obtained after separation. The slag phase is separated after being directly taken out of the furnace for casting, and the refined ferrophosphorus product is obtained. By testing the obtained refined ferrophosphorus product, it is found that the contents of each element in the ferrophosphorus are calculated by mass percentage as follows: P: 22.18wt.%; Ti: 0.058wt.%; Mn: 0.66wt.%, V: 0.76wt.%, and the remainder is Fe and inevitable impurities (in the high-temperature refining process, P is volatilized to a certain extent, so although the impurity elements are removed, P is also volatilized to a certain extent, so the percentage content of P remains basically unchanged and will not increase).

[0033] Example 2

[0034] The other configurations of this embodiment are exactly the same as those of embodiment 1 (step (1) and step (2)), except that in step (3), intermittent carbon dioxide injection is not provided, but continuous injection is performed for 40 minutes. The other configurations of step (3) are exactly the same as those of embodiment 1, and refined ferrophosphorus is obtained after casting. By testing the obtained refined ferrophosphorus product, the contents of each element in the ferrophosphorus are obtained in terms of mass percentage: P: 22.58wt.%; Ti: 0.076wt.%; Mn: 0.73wt.%, V: 0.81wt.%, and the remainder is Fe and unavoidable impurities.

[0035] In other specific embodiments of the present invention, the weight ratio of ordinary ferrophosphorus to slag-forming agent can also be set to, for example, 81, 85, 93, 102, 115, 121, 128 parts by weight of ordinary ferrophosphorus and 9.5, 10.2, 10.8, 11.3, 11.5, etc. parts by weight.

[0036] In other specific embodiments of the present invention, the limestone, silica and dolomite in the slag-forming agent can be mixed in a weight ratio of, for example, (4.2, 4.5, 4.2, 4.5, 5.1, 5.3, 5.9, etc.): (1.6, 1.8, 2.1, 2.2, 2.5, etc.): (2.7, 2.8, 3.0, 3.1, 3.2, 3.3, etc.).

[0037] In other specific embodiments of the present invention, the temperature of the molten ordinary ferrophosphorus in step (2) can be set to 1320°C, 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C, 1410°C, 1420°C, 1430°C, 1435°C, 1440°C, 1442°C, 1445°C, etc.; the temperature of the molten slag-forming agent can be set to 1495°C, 1498°C, 1505°C, 1510°C, 1515°C, etc.; the melt is naturally cooled to 1250°C, 1280°C, 1300°C, 1350°C, 1410°C, 1420°C, 1430°C, 1440°C, 1445°C, etc.

[0038] In other specific embodiments of the present invention, the distance between the nozzle of the oxygen lance and the melt surface is, for example, 32 cm, 35 cm, 38 cm, 42 cm, 45 cm, 48 cm, 49 cm, etc.; the Mach number M of the oxygen lance nozzle outlet is, for example, 1.8, 1.9, 2.0, 2.1, etc.; the carbon dioxide gas blowing time is, for example, 32 min, 35 min, 38 min, 42 min, 45 min, 48 min, 49 min, etc.; the oxygen lance blowing of carbon dioxide is intermittent cyclic blowing, and the carbon dioxide is sprayed for 4.2 min, 4.3 min, 4.5 min, 4.9 min, 5.2 min, 5.5 min, 5.9 min, etc., and the blowing is stopped for 35 s, 40 s, 45 s, 50 s, 55 s, etc., and then the blowing is continued, and the cycle is repeated.

[0039] Comparative Example 1

[0040] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those of Example 1, except that no carbon dioxide injection is set in step (3), and the other steps and parameter settings are the same as those of Example 1; the processing time of step (3) is recorded as 40 minutes. After the processing, the element content of the product is detected, and the results are shown in Table 1. Table 1 is a table of the removal ratios of the main impurity elements after ferrophosphorus refining in the examples and the comparative examples.

[0041] Comparative Example 2

[0042] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the carbon dioxide injection time in step (3) is 60 minutes. The other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected, and the removal rate of each major impurity element is obtained as shown in Table 1.

[0043] Comparative Example 3

[0044] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that step (3) sets the melt temperature to 1600-1620°C, and the other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected, and the removal rate of each major impurity element is obtained as shown in Table 1.

[0045] Comparative Example 4

[0046] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the distance between the oxygen lance nozzle and the melt surface is 65 cm, and the other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected, and the removal rate of each major impurity element is obtained as shown in Table 1.

[0047] Comparative Example 5

[0048] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the distance between the oxygen lance nozzle and the melt surface is 25 cm, and the other settings are exactly the same as those in Example 1. Splashing was found 1 minute after the spraying started, and the process could not be continued for safety reasons.

[0049] Comparative Example 6

[0050] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the carbon dioxide injection time in step (3) is 21 minutes. The other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected, and the removal rate of each major impurity element is obtained as shown in Table 1.

[0051] Comparative Example 7

[0052] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those of Example 1, except that the Mach number M at the oxygen lance nozzle outlet is set to 2.8 when the carbon dioxide is sprayed in step (3). Splashing occurs about 1.5 minutes after the start of the spraying, and the process cannot be continued.

[0053] Comparative Example 8

[0054] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the oxygen lance nozzle nozzle outlet Mach number M is set to 1.3 during carbon dioxide injection in step (3), and the other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected to obtain the removal rate of each major impurity element as shown in Table 1.

[0055] Comparative Example 9

[0056] This comparative example uses a medium frequency induction furnace, and the other settings are the same as those in Example 1, except that the slag-making agent configured in step (1) is limestone, and the weight ratio of silica and dolomite is 5:1.3:4.5, and the other settings are exactly the same as those in Example 1. After the treatment, the element content of the product is detected, and the removal rate of each major impurity element is obtained as shown in Table 1.

[0057] Table 1

[0058]

[0059] It can be seen from the experimental results of the impurity element removal rates of the embodiments and comparative examples in Table 1 that: Example 2 does not use intermittent injection of carbon dioxide, and its impurity removal effect is also up to standard, but the overall impurity removal rate is lower than that of Example 1 when the overall parameters are set the same. This is because each injection does not give the generated oxides time to combine with the top slag. Due to the continuous injection disturbing the alloy liquid, a part of the generated oxides return to the metal phase, resulting in a certain degree of reduction in the impurity removal rate.

[0060] Comparative Example 1 does not use carbon dioxide injection, but only uses high-temperature melting of slag-forming agent and crude ferrophosphorus, which will cause a certain amount of impurities to enter the slag phase. However, this amount is very small and cannot achieve the purpose of refining and impurity removal.

[0061] In Comparative Example 2, the time of carbon dioxide blowing was extended, and the impurity removal rate was also improved to a certain extent, but this amount of improvement did not increase significantly with the large extension of the time, especially the removal rates of manganese and vanadium. Therefore, considering the requirements of production efficiency, cost and minimum impurity content, the upper limit of the blowing time of the present invention is limited to 40 minutes. If it exceeds this range, the amount of impurity removal will not increase significantly, and the production efficiency will be greatly reduced. The blowing time set in Comparative Example 6 is too short, and carbon dioxide does not fully react with impurities in the melt, that is, the reaction amount of carbon dioxide is not up to standard, which proves that the blowing time set in the present invention is a setting that matches the setting mode of the present invention.

[0062] In Comparative Example 3, the temperature of the carbon dioxide injection is increased, and its range is not within the scope defined by the present invention. Due to the increase in temperature, the Gibbs free energy of carbon, chromium and vanadium changes, so that the chromium impurity cannot be removed. More importantly, the removal ratio of vanadium, which is a relatively major impurity in ferrophosphorus, is greatly reduced, resulting in a decrease in the impurity removal effect, which proves that the setting of the injection temperature set in the present invention is closely coordinated with the injection of carbon dioxide.

[0063] In Comparative Example 4, since the height of the oxygen lance spraying is increased, this height cannot disturb the liquid surface, so that the carbon dioxide cannot be fully contacted with the metal liquid, thereby greatly reducing the impurity removal rate; while in Comparative Example 5, since the oxygen lance height is too low, the distance to the metal liquid is too close, resulting in splashing of slag or melt, which is very likely to cause further safety accidents. Therefore, it is proved that the range setting of the oxygen lance height set by the present invention is closely coordinated with the setting of carbon dioxide spraying.

[0064] Comparative Example 7 increases the Mach number of the injection to strengthen the stirring of the melt by the gas and strengthen the contact between the carbon dioxide and the impurities in the melt, but the injection is too intense, resulting in a splashing accident; Comparative Example 8 reduces the Mach number, and similarly, because the injection is too gentle, the stirring intensity of the melt by the gas is relatively insufficient, and thus the contact between the carbon dioxide and the impurity elements in the melt is relatively insufficient, resulting in insufficient removal of impurities. Therefore, it is clear that the injection intensity range setting set by the present invention is closely coordinated with the setting of the carbon dioxide injection.

[0065] Comparative Example 9 changes the composition ratio of the slag-forming agent. Since the present invention sets a specific carbon dioxide injection mode and parameter setting, the change in the composition of the slag-forming agent and the parameter setting of the carbon dioxide injection form a strong coordination effect. The experimental results show that the impurity removal effect of this comparative example becomes worse. It is analyzed that after the ratio changes, the melting point of the slag phase increases, which is not conducive to the flow of slag and metal melt, and maintaining the carbon dioxide injection parameters cannot strengthen the flow of slag and melt, thereby reducing the impurity removal effect. As an experimental science, this experiment verifies that the difference in the proportion of slag-forming agents will cause changes in the impurity removal effect of carbon dioxide injection, that is, the two have a strong coordination effect. The scope of the two and the scope of the coordination of each parameter of the present invention are the optimal ranges obtained by the present invention through a large number of simulation experiments and medium-sized experiments. This comparative example further proves that the setting of the slag-forming agent and the injection of carbon dioxide have a strong coordination effect.

[0066] The basic principles and comparative data of the present invention are described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0067] The words such as "including", "comprising", "having" and the like involved in the present invention are open words, which mean "including but not limited to", and can be used interchangeably therewith. The words "or" and "and" used herein mean the words "and / or", and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably therewith.

[0068] It should also be noted that in the device and method of the present invention, each component or each step can be decomposed and / or reassembled. Such decomposition and / or reassembly should be regarded as equivalent solutions of the present invention.

Claims

1. A method for refining ferrophosphorus by injecting carbon dioxide, characterized in that: The steps include: (1) Raw material preparation: 80-130 parts by weight of blocky common ferrophosphorus with a particle size or equivalent particle size greater than 50 cm; 9-12 parts by weight of a slag-forming agent with a particle size or equivalent particle size of 10-20 cm; the slag-forming agent is limestone, silica and dolomite mixed in a weight ratio of (4-6): (1.5-2.6): (2.6-3.5); (2) Melting: placing the common ferrophosphorus obtained in step (1) into an induction furnace for melting, heating the temperature to 1300-1450° C., maintaining the temperature for 30-40 min until the common ferrophosphorus is completely melted, adding the slag-forming agent obtained in step (1), and then continuously heating the temperature to 1490-1520° C., maintaining the temperature for 15-20 min until the slag-forming agent is completely melted, then powering off the induction furnace, stopping heating, and powering on the induction furnace again after the melt naturally cools to 1150-1450° C. and maintaining the temperature; (3) Carbon dioxide blowing refining, wherein carbon dioxide gas is blown onto the surface of the melt obtained by naturally cooling to 1150-1450° C. in step (2) through an oxygen lance, the distance between the nozzle of the oxygen lance and the melt surface is 30-50 cm, the Mach number M at the nozzle outlet of the oxygen lance is 1.7-2.2, the carbon dioxide gas blowing time is 30-50 min, and the melt is heated by an induction furnace during the blowing process to maintain the melt temperature at 1150-1450° C. After the blowing is completed, the temperature is raised to 1530-1600° C., and then the ferrophosphorus and slag in the induction furnace are cast into a mold together and allowed to stand until the temperature drops to room temperature, the upper slag and the lower ferrophosphorus are separated, and the upper slag is separated and removed to obtain refined ferrophosphorus.

2. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1, characterized in that: In step (3), the oxygen lance sprays carbon dioxide in an intermittent cycle. After each carbon dioxide spray of 4 to 6 minutes, the spraying is stopped for 30 to 60 seconds, and then the spraying is continued, repeating the cycle.

3. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: The contents of each element in the ferrophosphorus in step (1) are as follows by mass percentage: P: 22-25wt.%, Ti: 1.14-2.01wt.%, Mn: 2.19-3.18wt.%, V: 1.5-2.3wt.%, and the remainder is Fe and unavoidable impurities.

4. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: In the described limestone in step (1), the mass percentage content of CaCO3 is greater than 97wt.%, and the rest are inevitable impurities; the mass percentage content of SiO2 in silica is greater than 98wt.%, and the rest are inevitable impurities; in dolomite, the total mass percentage content of CaCO3 and MgCO3 is greater than 95wt.%, and the rest are inevitable impurities.

5. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: The weight ratio of the slag-forming agent is limestone:silica:dolomite=5:2:

3.

6. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: The induction furnace described in step (2) is a medium frequency induction furnace.

7. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1, characterized in that: In step (1), the weight ratio of ordinary ferrophosphorus to slag-forming agent is (90-120):

10.

8. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1, characterized in that: The carbon dioxide gas in step (3) is industrial carbon dioxide gas, and the oxygen lance is used to spray carbon dioxide in an intermittent cycle. After each carbon dioxide spray for 5 minutes, the spraying is stopped for 45 seconds, and then the spraying is continued in this cycle.

9. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: The contents of each element in the refined ferrophosphorus obtained in step (3) are as follows: P: 21-26wt.%, Ti: 0.05-0.07wt.%, Mn: 0.58-0.75wt.%, V: 0.68-0.91wt.%, and the remainder is Fe and unavoidable impurities.

10. The method for refining ferrophosphorus by injecting carbon dioxide according to claim 1 or 2, characterized in that: In step (1), 80 to 130 parts by weight of blocky common ferrophosphorus having a particle size or an equivalent particle size greater than 50 cm and less than 100 cm is prepared.

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