Method for preparing low-nitrogen metal manganese ingot by using argon

Abstract

The invention discloses a method for preparing a low-nitrogen metal manganese ingot by using argon, relates to the technical field of metal manganese ingot production, and aims to solve the technical problems of high production cost and nitrogen increase of the metal manganese ingot caused by low quality and production efficiency of the metal manganese ingot produced by a current vacuum furnace method. Comprising the following steps of raw material preparation, raw material smelting, metal manganese ingot forming and metal manganese ingot postprocessing, a high-power vacuumizing device and a complex in-furnace material cooling device are not needed, compared with a traditional vacuum furnace method, the equipment investment cost is greatly reduced, an argon protection mode is adopted, dependence on complex and expensive equipment is avoided, and the production cost is reduced. And in the production process, a large amount of electric energy consumption is reduced due to the fact that a high-power vacuumizing device does not need to be operated, energy consumption is extremely high due to the fact that the vacuumizing device in a traditional vacuum furnace method continuously operates to maintain a vacuum environment, and the argon supply device is relatively low in energy consumption and can remarkably reduce the energy cost due to long-term operation.

Description

Technical Field

[0001] The present invention relates to the technical field of metal manganese ingot production, and more specifically, to a method for preparing low-nitrogen metal manganese ingots by utilizing argon gas. Background Art

[0002] In modern industry, low-nitrogen manganese ingots are an important basic material and are widely used in steel, non-ferrous metal alloys and other fields. The existing production of low-nitrogen manganese ingots mostly relies on the vacuum furnace method. However, this traditional method has a series of defects that are difficult to overcome.

[0003] From the equipment point of view, the vacuum furnace method has extremely stringent requirements on the technical parameters of the melting type vacuum furnace. For example, the negative pressure parameters must be precisely controlled within a narrow range to ensure that the physical and chemical environment in the furnace meets the requirements for melting metal manganese ingots. The stability of the vacuum degree is also crucial. Slight fluctuations may lead to the mixing of impurities during the melting process or abnormal reactions between metal manganese and nitrogen. The temperature parameters not only need to be controlled with high precision, but also need to maintain a high degree of uniformity throughout the melting process, which poses a huge challenge to the design and performance of the heating system.

[0004] In order to meet these strict technical parameters, enterprises have to configure high-power vacuum devices and furnace material cooling devices. On the one hand, high-power vacuum devices are expensive, which increases the initial equipment investment cost of enterprises; on the other hand, they consume a lot of electricity during operation, and the energy cost remains high in long-term operation. The situation of furnace material cooling devices is similar. The complex cooling system design and the use of high-performance cooling components have greatly increased the equipment cost.

[0005] From a process perspective, even if the above equipment conditions are met, the vacuum furnace method still faces serious nitrogen increase problems in the actual production process. Under high-temperature smelting conditions, metallic manganese has strong chemical activity and is easy to react with nitrogen to form nitrided metallic manganese, which leads to an increase in the nitrogen content in the metallic manganese ingot. Moreover, metallic manganese and nitrogen may also form a solid solution metallic manganese nitrogen alloy body in the form of intercrystalline bonding, further exacerbating the problem of excessive nitrogen content. This nitrogen increase phenomenon not only affects the quality of low-nitrogen metallic manganese ingots, making them unable to meet the strict requirements of low nitrogen content in some high-end application fields, but also may cause the performance of alloy products produced using these metallic manganese ingots to decrease. In view of this, we propose a method for preparing low-nitrogen metallic manganese ingots using argon. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing low-nitrogen manganese metal ingots using argon gas, so as to solve the technical problems of low quality and production efficiency of manganese metal ingots produced by the current vacuum furnace method, resulting in high production cost and nitrogen addition of manganese metal ingots.

[0007] In order to solve the above technical problems, the present invention provides the following technical solution: a method for preparing a low-nitrogen metal manganese ingot using argon gas, comprising the following steps:

[0008] S1. Raw material preparation;

[0009] Select metals of specific composition as starting materials and perform pretreatment to improve the purity of the raw materials;

[0010] S2, raw material smelting;

[0011] Add the pretreated raw materials into the medium frequency furnace, select an appropriate filling amount, fill argon into the medium frequency furnace, monitor the argon pressure in the furnace, use automatic heating control, start the medium frequency furnace to heat and stir the raw materials, and monitor the mixing of impurity elements in real time;

[0012] S3, forming metal manganese ingot;

[0013] After the raw materials are melted, the state of the melt is observed to determine whether to discharge the material. When discharging the material, the melt is discharged into a casting mold, and argon gas is introduced to cover the surface of the liquid metal. A suitable cooling method is adopted to cool the melt in the casting mold to obtain a low-nitrogen manganese metal ingot.

[0014] S4, post-processing of metal manganese ingot;

[0015] After the low-nitrogen manganese ingot is cooled to room temperature, the low-nitrogen manganese ingot in the casting mold is taken out and slag removal is carried out. After the slag removal is completed, the low-nitrogen manganese ingot is crushed and screened by a crusher. After multiple crushing and screening operations, a low-nitrogen manganese ingot that meets the requirements is finally obtained.

[0016] The present invention does not require a high-power vacuum pumping device and a complex in-furnace material cooling device, and greatly reduces the equipment investment cost compared to the traditional vacuum furnace method. Since the traditional vacuum furnace method requires high-precision vacuum equipment to maintain specific negative pressure, vacuum degree and temperature parameters, and these equipment are expensive, the present method avoids the dependence on such complex and expensive equipment through argon protection, and in the production process, since there is no need to operate a high-power vacuum pumping device, a large amount of electricity consumption is reduced. In the traditional vacuum furnace method, the vacuum pumping device is continuously operated to maintain a vacuum environment, and the energy consumption is extremely high, while the argon supply device of the present invention has relatively low energy consumption, and long-term operation can significantly reduce energy costs.

[0017] Preferably, the S1 raw material preparation further comprises the following steps:

[0018] S101, raw material selection;

[0019] Carefully select metals with specific components as starting materials, and strictly control the quality of raw material suppliers, requiring them to provide raw materials with high purity and stable composition, with a manganese content of 97% to 98% and an iron content of 2% to 3%;

[0020] S102, raw material pretreatment;

[0021] The starting materials are screened, cleaned, dried and magnetically separated to reduce impurities in the starting materials and thereby improve the purity of the raw materials.

[0022] Preferably, the S102 raw material pretreatment further comprises the following steps:

[0023] S102a, particle screening formula: Let the raw material particle diameter be d, and the screening range be d min ≤d≤d max , where d min =2mm,d max =10mm, use professional screening equipment to make the raw materials purchased meet this range to ensure uniform heat transfer during the smelting process;

[0024] S102b, Basis for selection of cleaning solvent: The cleaning solvent is determined according to the type of impurities on the surface of the raw material. If the impurities are mainly oil, an organic solvent can be selected. If there are impurities such as metal oxides, a weak acid solution can be selected, but it must meet the condition of not over-reacting with metal manganese and iron. Assume that the impurity content after cleaning is C 杂质 , the impurity content before cleaning is C 杂质0 , requires cleaning after C 杂质 ≤C 杂质0 ≤k(k is the impurity removal coefficient, 0 <k<1);

[0025] S102c, Drying temperature control formula: Drying can be done by low temperature drying, the low temperature drying temperature T 烘干 Must meet 80℃≤T 烘干 ≤100℃, assuming the moisture content of the raw material is H, the moisture content after drying is H 干 , requiring H 干 ≤H×m(m is the water content reduction coefficient, 0 <m<1);

[0026] S102d, Principle of magnetic separation: Utilize the magnetic force F exerted on magnetic impurities in a magnetic field. 磁 =q m (v×B), where q m is the magnetic charge of the magnetic impurities, v is the movement speed of the magnetic impurities in the magnetic field, and B is the magnetic field strength. The possible mixed magnetic impurities are removed by a high-strength magnetic separator to further improve the purity of the raw materials.

[0027] Preferably, the S2 raw material smelting further comprises the following steps:

[0028] S201, Loading: Carefully load the pre-treated raw materials into the medium frequency furnace. During the loading process, pay attention to avoid spilling and collision of the raw materials to prevent damage to the raw materials or the introduction of new impurities. The loading amount M 装料 According to the rated capacity V of the medium frequency furnace 额定 and the charge density ρ required by the process 装料 Carry out precise control to meet the rated load M 装料 =ρ 装料 ×V 额定 ×n, where n is the charging factor, 0.8≤n≤0.95, ensuring that there is enough space in the furnace for melt flow and gas escape during the smelting process;

[0029] S202, argon filling and parameter setting;

[0030] Argon filling speed formula: Turn on the argon supply device, and after the loading is completed, slowly fill the furnace with argon. The initial filling speed v 氩气初始 Controlled at a lower level, set to v 氩气初始 =5+5×r, (r is the random adjustment coefficient, 0≤r≤1) cubic meters / hour to prevent the raw materials from being blown away by the airflow;

[0031] As the argon concentration in the furnace gradually increases, the filling speed is gradually increased until a stable argon flow rate v is reached. 氩气 , range, argon flow v 氩气 According to the size of the medium frequency furnace (the volume V 炉 represents) and loading capacity M 装料 Adjustments are generally made to meet And 20≤v 氩气 ≤40 cubic meters / hour;

[0032] At the same time, monitor the argon pressure P in the furnace 氩气 , keep the pressure slightly higher than the normal pressure P 常压 Within the range, satisfy P 氩气 =(1.01+0.09×s)P 常压 (s is the pressure adjustment coefficient, 0≤s≤1) to ensure that argon gas can effectively block the entry of air;

[0033] S203, heating start and parameter control;

[0034] Start the heating system of the medium frequency furnace and heat the raw materials in a gradual heating method. During the entire heating process, the temperature in the furnace is monitored in real time and at multiple points. The power output of the medium frequency furnace is accurately adjusted in conjunction with the temperature feedback control system to ensure the uniformity of the melt temperature.

[0035] S204, stirring and monitoring during smelting;

[0036] During the smelting process, the stirring device is started in time according to the state of the melt, and the chemical composition and physical state of the melt are continuously monitored during the smelting process. The content of metallic manganese and iron and whether there is any impurity element mixed in are regularly tested through spectral analysis and other technologies.

[0037] Preferably, the S203 heating start and parameter control further comprises the following steps:

[0038] S203a, heating rate formula: start the heating system of the medium frequency furnace, adopt the method of gradual heating, the initial heating rate v 升温初始 Set to v 升温初始 =5+3×t (t is the heating stage coefficient, 0≤t≤1)℃ / minute, when the temperature reaches T 暂停 (T 暂停 =800+800×u (u is the pause temperature adjustment coefficient, 0≤u≤1℃), the temperature rise is suspended and maintained for a period of time t 暂停 , so that the internal structure of the raw material is initially homogenized, and then the temperature is continued to rise, and the heating rate is adjusted to v 升温后续 =8+4×v (v is the subsequent heating stage coefficient, 0≤v≤1)℃ / min, until the temperature reaches T 熔炼 ;

[0039] S203b, Temperature uniformity control formula:

[0040] During the whole heating process, advanced temperature sensors (such as thermocouple sensors) are used to monitor the temperature in the furnace in real time and at multiple points. The temperature at the monitoring point is set as T i (i=1,2,…,n, n is the number of monitoring points), the average temperature is Temperature fluctuations Required ΔT max ≤3℃, through the temperature feedback control system, the power output of the medium frequency furnace is accurately adjusted to ensure the uniformity of the melt temperature.

[0041] Preferably, the stirring and monitoring during the S204 smelting process further includes the following steps:

[0042] S204a, stirring speed formula: During the smelting process, the stirring device is started in time according to the state of the melt, and the stirring speed v 搅拌 Adjust according to the viscosity η of the melt and the conditions in the furnace to meet RPM, stirring can be done by mechanical stirring or electromagnetic stirring. Mechanical stirring is achieved by rotating stirring paddles, while electromagnetic stirring uses the principle of electromagnetic induction to generate stirring force in the melt. The purpose of stirring is to promote full melting of raw materials and homogenization of components, and prevent local component segregation.

[0043] S204b, Chemical composition monitoring formula: At the same time, the chemical composition and physical state of the melt are continuously monitored during the smelting process, and the content of metallic manganese and iron is regularly detected by spectral analysis and other technologies. Assume that the actual content of metallic manganese is C Mn , the theoretical content is C Mn0 , the actual content of iron is C Fe , the theoretical content is C Fe0 , requirements |C Mn -C Mn0 |≤δ Mn And |C Fe -C Fe0 |≤δ Fe (δ Mn , δ Fe is the allowable value of content deviation), and whether there is any impurity element mixed in. If necessary, the melt quality can be optimized by adding an appropriate amount of adjusting agent, such as a deoxidizer or refining agent.

[0044] Preferably, the S3 metal manganese ingot forming further comprises the following steps:

[0045] S301, preparation for discharge: when the melt reaches the ideal melting state, the melt fluidity, color and temperature are observed, and after judgment, the discharge is prepared. Before discharge, the mold is preheated, and the preheating temperature T 预热 According to the thermal conductivity λ of the mold material, the size V of the manganese ingot 锰锭 And the melting point of manganese ingot 熔点 Confirm, satisfy The purpose of preheating is to prevent the liquid metal from solidifying or causing stress concentration due to excessive temperature difference when entering the mold.

[0046] S302, discharging and casting;

[0047] Open the outlet of the medium frequency furnace to allow the liquid metal to flow into the mold, and continue to introduce argon gas to ensure that the argon gas can completely cover the surface of the liquid metal, so as to facilitate the demoulding of the metal manganese ingot and ensure the surface quality;

[0048] S303, cooling method selection and parameter control;

[0049] After the casting is completed, a suitable cooling method is selected according to the size of the metal manganese ingot, which may be one or a combination of natural cooling, air cooling, and water cooling.

[0050] Preferably, the S302 discharging and casting also includes the following steps:

[0051] S302a, discharge speed formula: open the discharge port of the medium frequency furnace, and let the liquid metal flow slowly and steadily into the pre-prepared mold. The discharge speed v 出料According to the capacity V of the mold 铸模 and the viscosity η of the melt to meet Among them, τ is the discharge time coefficient, which is used to avoid excessive discharge, which may cause liquid metal to overflow or generate turbulence, thus affecting the quality of the casting mold;

[0052] S302b, during the molding process, argon gas is continuously and stably introduced, and the argon gas flow rate v 氩气铸模 Maintained at 15-25 cubic meters per hour, argon is evenly distributed on the surface of the liquid metal through a specially designed gas distribution system to form a continuous and stable protective gas film. The gas distribution system can adopt a porous nozzle design to ensure that the argon can completely cover the surface of the liquid metal. The design of the mold is based on the final shape and size requirements of the metal manganese ingot. The mold material is graphite with good thermal conductivity and demolding properties. The internal surface of the mold is finely processed and treated with high smoothness and low roughness to facilitate the demolding of the metal manganese ingot and ensure the surface quality.

[0053] Preferably, the cooling method selection and parameter control in S303 further includes the following steps:

[0054] S303a, Natural cooling rate formula: After the mold is completed, for smaller-sized manganese ingots, natural cooling can be used. During the natural cooling process, the mold is placed in a well-ventilated and relatively stable temperature environment. Assume that the ambient temperature is T 环境 , the temperature of the manganese ingot is T 锰锭 , the cooling time is t 冷却 , by setting temperature sensors around the mold to monitor the cooling speed in real time: Ensure that the cooling rate is controlled at 5-15℃ / hour;

[0055] S303b, air cooling speed formula: For manganese ingots with larger size or special performance requirements, a cooling method combining air cooling and water cooling can be used. First, air cooling is used for preliminary cooling, and the air cooling speed v 风冷 According to the air cooling equipment power P 风冷 , the surface area S of the metal manganese ingot and the temperature difference ΔT between the metal manganese ingot and the air 风冷 Confirm, satisfy Among them, k 风冷 is the air cooling efficiency coefficient, 0.5≤k 风冷 ≤1, air cooling rate is 10-20℃ / hour, air cooling time t 风冷 Determined according to the size of the metal manganese ingot and the temperature change;

[0056] S303c, water cooling speed formula: After the temperature of the metal manganese ingot drops to a certain level, water cooling is carried out. Water cooling is achieved by setting cooling water pipes or water tanks around the mold. The water cooling speed v 水冷 According to the water flow Q水 , specific heat capacity of water c 水 , water temperature T 水 、Mass of metal manganese ingot m 锰锭 Specific heat capacity of manganese ingot c 锰锭 and the temperature difference between the manganese ingot and the water ΔT 水冷 Confirm, satisfy:

[0057]

[0058] Among them, k 水冷 is the water cooling efficiency coefficient, 0.8≤k 水冷 ≤1, water cooling speed v 水冷 Controlled at 20-40℃ / hour, during the water cooling process, accurately control the water flow and temperature T 水 , water temperature T 水 Keep the temperature between 20-30℃ to avoid cracks on the surface of the manganese ingot or excessive internal stress due to too fast water cooling speed or too low water temperature.

[0059] Preferably, the post-processing of the S4 metal manganese ingot further comprises the following steps:

[0060] S401, slag removal preparation;

[0061] After the manganese ingot is cooled to room temperature, it is taken out of the mold and prepared for slag removal. Before slag removal, the manganese ingot is visually inspected to see if there are any obvious surface defects. If there are any defective manganese ingots, they need to be marked and handled separately. At the same time, the appropriate slag removal method and equipment are selected according to the surface condition and impurity type of the manganese ingot.

[0062] S402, slag removal operation;

[0063] Mechanical slag removal efficiency formula: If the impurities on the surface of the manganese ingot are mainly loose slag and oxides, mechanical slag removal equipment can be used for treatment. The mechanical slag removal equipment can use a rotating scraper, a high-pressure air purge device or a combination of the two. Suppose the rotating scraper speed is n 刮刀 , then n 刮刀 =50+50×y rpm, where y is the scraper speed adjustment coefficient, 0≤y≤1, and the high-pressure air purge pressure is P 空气 ,but Where z is the air pressure adjustment factor;

[0064] S403, crushing operation;

[0065] After completing the slag removal operation on the low-nitrogen manganese ingot, the crusher is controlled to crush the low-nitrogen manganese ingot. The crushed low-nitrogen manganese ingot is screened by screening equipment to remove particles that do not meet the particle size requirements. After multiple crushing and screening operations, low-nitrogen manganese ingots that meet the requirements are finally obtained.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] 1. The present invention does not require a high-power vacuum pumping device and a complex furnace material cooling device. Compared with the traditional vacuum furnace method, the equipment investment cost is greatly reduced. Since the traditional vacuum furnace method requires high-precision vacuum equipment to maintain specific negative pressure, vacuum degree and temperature parameters, and these equipment are expensive, the present method avoids the dependence on such complex and expensive equipment through argon protection. In the production process, since there is no need to run a high-power vacuum pumping device, a large amount of electricity consumption is reduced. In the traditional vacuum furnace method, the vacuum pumping device is continuously operated to maintain a vacuum environment, and the energy consumption is extremely high. The argon supply device of the present invention has relatively low energy consumption, and long-term operation can significantly reduce energy costs.

[0068] 2. The present invention adopts argon protection throughout the process, which effectively blocks the contact between air and charge, and completely solves the problem of increasing nitrogen by combining metal manganese with nitrogen at high temperature and increasing nitrogen by combining metal manganese and nitrogen between crystals to form a solid solution metal manganese nitrogen alloy body. In this way, the nitrogen content of the prepared metal manganese ingot is much lower than that of the product produced by the traditional vacuum furnace method, which can meet the strict requirements of high-end application fields for low nitrogen content. In addition, the screening, cleaning, drying and magnetic separation steps in the raw material pretreatment process effectively remove impurities in the raw materials and ensure the high purity of the raw materials. The stirring and monitoring during the smelting process and the reasonable cooling control during the molding process make the internal structure of the metal manganese ingot more uniform, avoid internal defects caused by impurities or uneven temperature, and further improve the quality of the metal manganese ingot.

[0069] 3. The process of the present invention is simpler than the traditional vacuum furnace method, reducing the complex vacuum parameter control links and the maintenance time of related equipment. For example, there is no need to frequently adjust the negative pressure, vacuum degree and other parameters of the vacuum furnace, reducing the difficulty of operation and the downtime caused by equipment failure, thereby improving the overall production efficiency. By precisely controlling the process parameters, such as melting temperature, heating rate, cooling rate, etc., the stability of the production process is guaranteed, the scrap rate caused by process fluctuations is reduced, and the production can be carried out continuously and efficiently. DETAILED DESCRIPTION

[0070] The present invention relates to a method for preparing a low-nitrogen metal manganese ingot using argon gas, comprising the following steps:

[0071] S1. Raw material preparation;

[0072] Select metals of specific composition as starting materials and perform pretreatment to improve the purity of the raw materials;

[0073] S101, raw material selection;

[0074] Carefully select metals with specific components as starting materials, and strictly control the quality of raw material suppliers, requiring them to provide raw materials with high purity and stable composition, with a manganese content of 97% to 98% and an iron content of 2% to 3%;

[0075] S102, raw material pretreatment;

[0076] Screening, washing, drying and magnetic separation of the starting materials to reduce impurities in the starting materials and thus improve the purity of the raw materials;

[0077] S102a, particle screening formula: Let the raw material particle diameter be d, and the screening range be d min ≤d≤d max , where d min =2mm,d max =10mm, use professional screening equipment to make the raw materials purchased meet this range to ensure uniform heat transfer during the smelting process;

[0078] S102b, Basis for selection of cleaning solvent: The cleaning solvent is determined according to the type of impurities on the surface of the raw material. If the impurities are mainly oil, an organic solvent can be selected. If there are impurities such as metal oxides, a weak acid solution can be selected, but it must meet the condition of not over-reacting with metal manganese and iron. Assume that the impurity content after cleaning is C 杂质 , the impurity content before cleaning is C 杂质0 , requires cleaning after C 杂质 ≤C 杂质0 ≤k(k is the impurity removal coefficient, 0 <k<1);

[0079] S102c, Drying temperature control formula: Drying can be done by low temperature drying, the low temperature drying temperature T 烘干 Must meet 80℃≤T 烘干 ≤100℃, assuming the moisture content of the raw material is H, the moisture content after drying is H 干 , requiring H 干 ≤H×m(m is the water content reduction coefficient, 0 <m<1);

[0080] S102d, Principle of magnetic separation: Utilize the magnetic force F exerted on magnetic impurities in a magnetic field. 磁 =q m (v×B), where q mis the magnetic charge of the magnetic impurities, v is the speed of the magnetic impurities in the magnetic field, and B is the magnetic field strength. The high-strength magnetic separator is used to remove the possible mixed magnetic impurities to further improve the purity of the raw materials;

[0081] S2, raw material smelting;

[0082] Add the pretreated raw materials into the medium frequency furnace, select an appropriate filling amount, fill argon into the medium frequency furnace, monitor the argon pressure in the furnace, use automatic heating control, start the medium frequency furnace to heat and stir the raw materials, and monitor the mixing of impurity elements in real time;

[0083] S201, Loading: Carefully load the pre-treated raw materials into the medium frequency furnace. During the loading process, pay attention to avoid spilling and collision of the raw materials to prevent damage to the raw materials or the introduction of new impurities. The loading amount M 装料 According to the rated capacity V of the medium frequency furnace 额定 and the charge density ρ required by the process 装料 Carry out precise control to meet the rated load M 装料 =ρ 装料 ×V 额定 ×n, where n is the charging factor, 0.8≤n≤0.95, ensuring that there is enough space in the furnace for melt flow and gas escape during the smelting process;

[0084] S202, argon filling and parameter setting;

[0085] Argon filling speed formula: Turn on the argon supply device, and after the loading is completed, slowly fill the furnace with argon. The initial filling speed v 氩气初始 Controlled at a lower level, set to v 氩气初始 =5+5×r, (r is the random adjustment coefficient, 0≤r≤1) cubic meters / hour to prevent the raw materials from being blown away by the airflow;

[0086] As the argon concentration in the furnace gradually increases, the filling speed is gradually increased until a stable argon flow rate v is reached. 氩气 , range, argon flow v 氩气 According to the size of the medium frequency furnace (the volume V 炉 represents) and loading capacity M 装料 Adjustments are generally made to meet And 20≤v 氩气 ≤40 cubic meters / hour;

[0087] At the same time, monitor the argon pressure P in the furnace 氩气 , keep the pressure slightly higher than the normal pressure P 常压 Within the range, satisfy P 氩气 =(1.01+0.09×s)P 常压(s is the pressure adjustment coefficient, 0≤s≤1) to ensure that argon gas can effectively block the entry of air;

[0088] S203, heating start and parameter control;

[0089] Start the heating system of the medium frequency furnace and heat the raw materials in a gradual heating method. During the entire heating process, the temperature in the furnace is monitored in real time and at multiple points. The power output of the medium frequency furnace is accurately adjusted in conjunction with the temperature feedback control system to ensure the uniformity of the melt temperature.

[0090] S203a, heating rate formula: start the heating system of the medium frequency furnace, adopt the method of gradual heating, the initial heating rate v 升温初始 Set to v 升温初始 =5+3×t (t is the heating stage coefficient, 0≤t≤1)℃ / minute, when the temperature reaches T 暂停 (T 暂停 =800+800×u (u is the pause temperature adjustment coefficient, 0≤u≤1℃), the temperature rise is suspended and maintained for a period of time t 暂停 , so that the internal structure of the raw material is initially homogenized, and then the temperature is continued to rise, and the heating rate is adjusted to v 升温后续 =8+4×v (v is the subsequent heating stage coefficient, 0≤v≤1)℃ / min, until the temperature reaches T 熔炼 ;

[0091] S203b, Temperature uniformity control formula:

[0092] During the whole heating process, advanced temperature sensors (such as thermocouple sensors) are used to monitor the temperature in the furnace in real time and at multiple points. The temperature at the monitoring point is set as T i (i=1,2,…,n, n is the number of monitoring points), the average temperature is Temperature fluctuations Required ΔT max ≤3℃, through the temperature feedback control system, the power output of the medium frequency furnace is accurately adjusted to ensure the uniformity of the melt temperature;

[0093] S204, stirring and monitoring during smelting;

[0094] During the smelting process, the stirring device is started in time according to the state of the melt, and the chemical composition and physical state of the melt are continuously monitored during the smelting process. The content of metal manganese and iron and whether there are any impurity elements mixed in are regularly detected through spectral analysis and other technologies;

[0095] S204a, stirring speed formula: During the smelting process, the stirring device is started in time according to the state of the melt, and the stirring speed v 搅拌 Adjust according to the viscosity η of the melt and the conditions in the furnace to meet RPM, stirring can be done by mechanical stirring or electromagnetic stirring. Mechanical stirring is achieved by rotating stirring paddles, while electromagnetic stirring uses the principle of electromagnetic induction to generate stirring force in the melt. The purpose of stirring is to promote full melting of raw materials and homogenization of components, and prevent local component segregation.

[0096] S204b, Chemical composition monitoring formula: At the same time, the chemical composition and physical state of the melt are continuously monitored during the smelting process, and the content of metallic manganese and iron is regularly detected by spectral analysis and other technologies. Assume that the actual content of metallic manganese is C Mn , the theoretical content is C Mn0 , the actual content of iron is C Fe , the theoretical content is C Fe0 , requirements |C Mn -C Mn0 |≤δ Mn And |C Fe -C Fe0 |≤δ Fe (δ Mn , δ Fe is the content deviation allowable value), and whether there is any impurity element mixed in. If necessary, the melt quality can be optimized by adding an appropriate amount of adjusting agent, such as a deoxidizer or a refining agent;

[0097] S3, forming metal manganese ingot;

[0098] After the raw materials are melted, the state of the melt is observed to determine whether to discharge the material. When discharging the material, the melt is discharged into a casting mold, and argon gas is introduced to cover the surface of the liquid metal. A suitable cooling method is adopted to cool the melt in the casting mold to obtain a low-nitrogen manganese metal ingot.

[0099] S301, preparation for discharge: when the melt reaches the ideal melting state, the melt fluidity, color and temperature are observed, and after judgment, the discharge is prepared. Before discharge, the mold is preheated, and the preheating temperature T 预热 According to the thermal conductivity λ of the mold material, the size V of the manganese ingot 锰锭 And the melting point of manganese ingot 熔点 Confirm, satisfy The purpose of preheating is to prevent the liquid metal from solidifying or causing stress concentration due to excessive temperature difference when entering the mold.

[0100] S302, discharging and casting;

[0101] Open the outlet of the medium frequency furnace to allow the liquid metal to flow into the mold, and continue to introduce argon gas to ensure that the argon gas can completely cover the surface of the liquid metal, so as to facilitate the demoulding of the metal manganese ingot and ensure the surface quality;

[0102] S302a, discharge speed formula: open the discharge port of the medium frequency furnace, and let the liquid metal flow slowly and steadily into the pre-prepared mold. The discharge speed v 出料 According to the capacity V of the mold 铸模 and the viscosity η of the melt to meet Among them, τ is the discharge time coefficient, which is used to avoid excessive discharge, which may cause liquid metal to overflow or generate turbulence, thus affecting the quality of the casting mold;

[0103] S302b, during the molding process, argon gas is continuously and stably introduced, and the argon gas flow rate v 氩气铸模 Maintained at 15-25 cubic meters per hour, argon is evenly distributed on the surface of the liquid metal through a specially designed gas distribution system to form a continuous and stable protective gas film. The gas distribution system can adopt a multi-hole nozzle design to ensure that the argon can completely cover the surface of the liquid metal. The design of the mold is based on the final shape and size requirements of the metal manganese ingot. The mold material is graphite with good thermal conductivity and demoulding performance. The internal surface of the mold is finely processed and treated with high smoothness and low roughness to facilitate the demoulding of the metal manganese ingot and ensure the surface quality;

[0104] S303, cooling method selection and parameter control;

[0105] After the casting is completed, according to the size of the metal manganese ingot, a suitable cooling method is selected, which is one or more combinations of natural cooling, air cooling, and water cooling;

[0106] S303a, Natural cooling rate formula: After the mold is completed, for smaller-sized manganese ingots, natural cooling can be used. During the natural cooling process, the mold is placed in a well-ventilated and relatively stable temperature environment. Assume that the ambient temperature is T 环境 , the temperature of the manganese ingot is T 锰锭 , the cooling time is t 冷却 , by setting temperature sensors around the mold to monitor the cooling speed in real time: Ensure that the cooling rate is controlled at 5-15℃ / hour;

[0107] S303b, air cooling speed formula: For manganese ingots with larger size or special performance requirements, a cooling method combining air cooling and water cooling can be used. First, air cooling is used for preliminary cooling, and the air cooling speed v 风冷 According to the air cooling equipment power P 风冷 , the surface area S of the metal manganese ingot and the temperature difference ΔT between the metal manganese ingot and the air 风冷 Confirm, satisfy Among them, k 风冷 is the air cooling efficiency coefficient, 0.5≤k 风冷 ≤1, air cooling rate is 10-20℃ / hour, air cooling time t 风冷Determined according to the size of the metal manganese ingot and the temperature change;

[0108] S303c, water cooling speed formula: After the temperature of the metal manganese ingot drops to a certain level, water cooling is carried out. Water cooling is achieved by setting cooling water pipes or water tanks around the mold. The water cooling speed v 水冷 According to the water flow Q 水 Specific heat capacity of water T 水 , water temperature 水 、Mass of metal manganese ingot m 锰锭 Specific heat capacity of manganese ingot c 锰锭 and the temperature difference between the manganese ingot and the water ΔT 水冷 Confirm, satisfy:

[0109]

[0110] Among them, k 水冷 is the water cooling efficiency coefficient, 0.8≤k 水冷 ≤1, water cooling speed v 水冷 Controlled at 20-40℃ / hour, during the water cooling process, accurately control the water flow and temperature T 水 , water temperature T 水 Keep the temperature between 20-30℃ to avoid cracks on the surface of the manganese ingot or excessive internal stress due to too fast water cooling speed or too low water temperature;

[0111] S4, post-processing of metal manganese ingot;

[0112] After the low-nitrogen manganese metal ingot is cooled to room temperature, the low-nitrogen manganese metal ingot is taken out from the casting mold and deslagging is performed. After the deslagging is completed, the low-nitrogen manganese metal ingot is crushed and screened by a crusher. After multiple crushing and screening operations, a low-nitrogen manganese metal ingot that meets the requirements is finally obtained.

[0113] S401, slag removal preparation;

[0114] After the manganese ingot is cooled to room temperature, it is taken out of the mold and prepared for slag removal. Before slag removal, the manganese ingot is visually inspected to see if there are any obvious surface defects. If there are any defective manganese ingots, they need to be marked and handled separately. At the same time, the appropriate slag removal method and equipment are selected according to the surface condition and impurity type of the manganese ingot.

[0115] S402, slag removal operation;

[0116] Mechanical slag removal efficiency formula: If the impurities on the surface of the manganese ingot are mainly loose slag and oxides, mechanical slag removal equipment can be used for treatment. The mechanical slag removal equipment can use a rotating scraper, a high-pressure air purge device or a combination of the two. Suppose the rotating scraper speed is n 刮刀 , then n 刮刀=50+50×y rpm, where y is the scraper speed adjustment coefficient, 0≤y≤1, and the high-pressure air purge pressure is P 空气 ,but Where z is the air pressure adjustment factor;

[0117] S403, crushing operation;

[0118] After completing the slag removal operation on the low-nitrogen manganese ingot, the crusher is controlled to crush the low-nitrogen manganese ingot. The crushed low-nitrogen manganese ingot is screened by screening equipment to remove particles that do not meet the particle size requirements. After multiple crushing and screening operations, low-nitrogen manganese ingots that meet the requirements are finally obtained.

[0119] The present invention does not require a high-power vacuum pumping device and a complex in-furnace material cooling device, and greatly reduces the equipment investment cost compared to the traditional vacuum furnace method. Since the traditional vacuum furnace method requires high-precision vacuum equipment to maintain specific negative pressure, vacuum degree and temperature parameters, and these equipment are expensive, the present method avoids the dependence on such complex and expensive equipment through argon protection, and in the production process, since there is no need to operate a high-power vacuum pumping device, a large amount of electricity consumption is reduced. In the traditional vacuum furnace method, the vacuum pumping device is continuously operated to maintain a vacuum environment, and the energy consumption is extremely high, while the argon supply device of the present invention has relatively low energy consumption, and long-term operation can significantly reduce energy costs.

[0120] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a low-nitrogen manganese metal ingot using argon, characterized in that: The following steps are involved: S1. Raw material preparation; Select metals of specific composition as starting materials and perform pretreatment to improve the purity of the raw materials; S2, raw material smelting; Add the pretreated raw materials into the medium frequency furnace, select an appropriate filling amount, fill argon into the medium frequency furnace, monitor the argon pressure in the furnace, use automatic heating control, start the medium frequency furnace to heat and stir the raw materials, and monitor the mixing of impurity elements in real time; S3, forming metal manganese ingot; After the raw materials are melted, the state of the melt is observed to determine whether to discharge the material. When discharging the material, the melt is discharged into a casting mold, and argon gas is introduced to cover the surface of the liquid metal. A suitable cooling method is adopted to cool the melt in the casting mold to obtain a low-nitrogen manganese metal ingot. S4, post-processing of metal manganese ingot; After the low-nitrogen manganese ingot is cooled to room temperature, the low-nitrogen manganese ingot in the casting mold is taken out and slag removal is carried out. After the slag removal is completed, the low-nitrogen manganese ingot is crushed and screened by a crusher. After multiple crushing and screening operations, a low-nitrogen manganese ingot that meets the requirements is finally obtained.

2. The method for preparing a low-nitrogen manganese metal ingot using argon according to claim 1, characterized in that: The S1 raw material preparation also includes the following steps: S101, raw material selection; Carefully select metals with specific components as starting materials, and strictly control the quality of raw material suppliers, requiring them to provide raw materials with high purity and stable composition, with a manganese content of 97% to 98% and an iron content of 2% to 3%; S102, raw material pretreatment; The starting materials are screened, cleaned, dried and magnetically separated to reduce impurities in the starting materials and thereby improve the purity of the raw materials.

3. The method for preparing a low-nitrogen manganese metal ingot using argon according to claim 2, characterized in that: The S102 raw material pretreatment also includes the following steps: S102a, particle screening formula: Let the raw material particle diameter be d, and the screening range be d min ≤d≤d max , where d min =2mm,d max =10mm, use professional screening equipment to make the raw materials purchased meet this range to ensure uniform heat transfer during the smelting process; S102b, Basis for selection of cleaning solvent: The cleaning solvent is determined according to the type of impurities on the surface of the raw material. If the impurities are mainly oil, an organic solvent can be selected. If there are impurities such as metal oxides, a weak acid solution can be selected, but it must meet the condition of not over-reacting with metal manganese and iron. Assume that the impurity content after cleaning is C 杂质 , the impurity content before cleaning is C 杂质0 , requires cleaning after C 杂质 ≤C 杂质0 ≤k(k is the impurity removal coefficient, 0 <k<1); S102c, Drying temperature control formula: Drying can be done by low temperature drying, the low temperature drying temperature T 烘干 Must meet 80℃≤T 烘干 ≤100℃, assuming the moisture content of the raw material is H, the moisture content after drying is H 干 , requiring H 干 ≤H×m(m is the water content reduction coefficient, 0 <m<1); S102d, Principle of magnetic separation: Utilize the magnetic force F exerted on magnetic impurities in a magnetic field. 磁 =q m (v×B), where q m is the magnetic charge of the magnetic impurities, v is the movement speed of the magnetic impurities in the magnetic field, and B is the magnetic field strength. The possible mixed magnetic impurities are removed by a high-strength magnetic separator to further improve the purity of the raw materials.

4. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 1, characterized in that: The S2 raw material smelting also includes the following steps: S201, Loading: Carefully load the pre-treated raw materials into the medium frequency furnace. During the loading process, pay attention to avoid spilling and collision of the raw materials to prevent damage to the raw materials or the introduction of new impurities. The loading amount M 装料 According to the rated capacity V of the medium frequency furnace 额定 and the charge density ρ required by the process 装料 Carry out precise control to meet the rated load M 装料 =ρ 装料 ×V 额定 ×n, where n is the charging factor, 0.8≤n≤0.95, ensuring that there is enough space in the furnace for melt flow and gas escape during the smelting process; S202, argon filling and parameter setting; Argon filling speed formula: Turn on the argon supply device, and after the loading is completed, slowly fill the furnace with argon. The initial filling speed v 氩气初始 Controlled at a lower level, set to v 氩气初始 =5+5×r, (r is the random adjustment coefficient, 0≤r≤1) cubic meters / hour to prevent the raw materials from being blown away by the airflow; As the argon concentration in the furnace gradually increases, the filling speed is gradually increased until a stable argon flow rate v is reached. 氩气 , range, argon flow v 氩气 According to the size of the medium frequency furnace (the volume V 炉 represents) and loading capacity M 装料 Adjustments are generally made to meet Cubic meters / hour, and 20≤v 氩气 ≤40 cubic meters / hour; At the same time, monitor the argon pressure P in the furnace 氩气 , keep the pressure slightly higher than the normal pressure P 常压 Within the range, satisfy P 氩气 =(1.01+0.09×s)P 常压 (s is the pressure adjustment coefficient, 0≤s≤1) to ensure that argon gas can effectively block the entry of air; S203, heating start and parameter control; Start the heating system of the medium frequency furnace and heat the raw materials in a gradual heating method. During the entire heating process, the temperature in the furnace is monitored in real time and at multiple points. The power output of the medium frequency furnace is accurately adjusted in conjunction with the temperature feedback control system to ensure the uniformity of the melt temperature. S204, stirring and monitoring during smelting; During the smelting process, the stirring device is started in time according to the state of the melt, and the chemical composition and physical state of the melt are continuously monitored during the smelting process. The content of metallic manganese and iron and whether there is any impurity element mixed in are regularly tested through spectral analysis and other technologies.

5. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 4, characterized in that: The S203 heating start and parameter control also includes the following steps: S203a, heating rate formula: start the heating system of the medium frequency furnace, adopt the method of gradual heating, the initial heating rate v 升温初始 Set to v 升温初始 =5+3×t (t is the heating stage coefficient, 0≤t≤1)℃ / minute, when the temperature reaches T 暂停 (T 暂停 =800+800×u (u is the pause temperature adjustment coefficient, 0≤u≤1℃), the temperature rise is suspended and maintained for a period of time t 暂停 , so that the internal structure of the raw material is initially homogenized, and then the temperature is continued to rise, and the heating rate is adjusted to v 升温后续 =8+4×v (v is the subsequent heating stage coefficient, 0≤v≤1)℃ / min, until the temperature reaches T 熔炼 ; S203b, Temperature uniformity control formula: During the whole heating process, advanced temperature sensors (such as thermocouple sensors) are used to monitor the temperature in the furnace in real time and at multiple points. The temperature at the monitoring point is set as T i (i=1,2,…,n, n is the number of monitoring points), the average temperature is Temperature fluctuations Required ΔT max ≤3℃, through the temperature feedback control system, the power output of the medium frequency furnace is accurately adjusted to ensure the uniformity of the melt temperature.

6. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 5, characterized in that: The stirring and monitoring during the S204 smelting process also includes the following steps: S204a, stirring speed formula: During the smelting process, the stirring device is started in time according to the state of the melt, and the stirring speed v 搅拌 Adjust according to the viscosity η of the melt and the conditions in the furnace to meet RPM, stirring can be done by mechanical stirring or electromagnetic stirring. Mechanical stirring is achieved by rotating stirring paddles, while electromagnetic stirring uses the principle of electromagnetic induction to generate stirring force in the melt. The purpose of stirring is to promote full melting of raw materials and homogenization of components, and prevent local component segregation. S204b, Chemical composition monitoring formula: At the same time, the chemical composition and physical state of the melt are continuously monitored during the smelting process, and the content of metallic manganese and iron is regularly detected by spectral analysis and other technologies. Assume that the actual content of metallic manganese is C Mn , the theoretical content is C Mn0 , the actual content of iron is C Fe , the theoretical content is C Fe0 , requirements |C Mn -C Mn0 |≤δ Mn And |C Fe -C Fe0 |≤δ Fe (δ Mn , δ Fe is the allowable value of content deviation), and whether there is any impurity element mixed in. If necessary, the melt quality can be optimized by adding an appropriate amount of adjusting agent, such as a deoxidizer or refining agent.

7. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 1, characterized in that: The S3 manganese metal ingot forming also includes the following steps: S301, preparation for discharge: when the melt reaches the ideal melting state, the melt fluidity, color and temperature are observed, and after judgment, the discharge is prepared. Before discharge, the mold is preheated, and the preheating temperature T 预热 According to the thermal conductivity λ of the mold material, the size V of the manganese ingot 锰锭 And the melting point of manganese ingot 熔点 Confirm, satisfy The purpose of preheating is to prevent the liquid metal from solidifying or causing stress concentration due to excessive temperature difference when entering the mold. S302, discharging and casting; Open the outlet of the medium frequency furnace to allow the liquid metal to flow into the mold, and continue to introduce argon gas to ensure that the argon gas can completely cover the surface of the liquid metal, so as to facilitate the demoulding of the metal manganese ingot and ensure the surface quality; S303, cooling method selection and parameter control; After the casting is completed, a suitable cooling method is selected according to the size of the metal manganese ingot, which may be one or a combination of natural cooling, air cooling, and water cooling.

8. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 7, characterized in that: The S302 discharging and casting also includes the following steps: S302a, discharge speed formula: open the discharge port of the medium frequency furnace, and let the liquid metal flow slowly and steadily into the pre-prepared mold. The discharge speed v 出料 According to the capacity V of the mold 铸模 and the viscosity η of the melt to meet Among them, τ is the discharge time coefficient, which is used to avoid excessive discharge, which may cause liquid metal to overflow or generate turbulence, thus affecting the quality of the casting mold; S302b, during the molding process, argon gas is continuously and stably introduced, and the argon gas flow rate v 氩气铸模 Maintained at 15-25 cubic meters per hour, argon is evenly distributed on the surface of the liquid metal through a specially designed gas distribution system to form a continuous and stable protective gas film. The gas distribution system can adopt a porous nozzle design to ensure that the argon can completely cover the surface of the liquid metal. The design of the mold is based on the final shape and size requirements of the metal manganese ingot. The mold material is graphite with good thermal conductivity and demolding properties. The internal surface of the mold is finely processed and treated with high smoothness and low roughness to facilitate the demolding of the metal manganese ingot and ensure the surface quality.

9. The method for preparing a low-nitrogen manganese metal ingot using argon according to claim 8, characterized in that: The cooling method selection and parameter control in step S303 also includes the following steps: S303a, Natural cooling rate formula: After the mold is completed, for smaller-sized manganese ingots, natural cooling can be used. During the natural cooling process, the mold is placed in a well-ventilated and relatively stable temperature environment. Assume that the ambient temperature is T 环境 , the temperature of the manganese ingot is T 锰锭 , the cooling time is t 冷却 , by setting temperature sensors around the mold to monitor the cooling speed in real time: Ensure that the cooling rate is controlled at 5-15℃ / hour; S303b, air cooling speed formula: For manganese ingots with larger size or special performance requirements, a cooling method combining air cooling and water cooling can be used. First, air cooling is used for preliminary cooling, and the air cooling speed v 风冷 According to the air cooling equipment power P 风冷 , the surface area S of the metal manganese ingot and the temperature difference ΔT between the metal manganese ingot and the air 风冷 Confirm, satisfy Among them, k 风冷 is the air cooling efficiency coefficient, 0.5≤k 风冷 ≤1, air cooling rate is 10-20℃ / hour, air cooling time t 风冷 Determined according to the size of the metal manganese ingot and the temperature change; S303c, water cooling speed formula: After the temperature of the metal manganese ingot drops to a certain level, water cooling is carried out. Water cooling is achieved by setting cooling water pipes or water tanks around the mold. The water cooling speed v 水冷 According to the water flow Q 水 , specific heat capacity of water c 水 , water temperature T 水 、Mass of metal manganese ingot m 锰锭 Specific heat capacity of manganese ingot c 锰锭 and the temperature difference between the manganese ingot and the water ΔT 水冷 Confirm, satisfy: Among them, k 水冷 is the water cooling efficiency coefficient, 0.8≤k 水冷 ≤1, water cooling speed v 水冷 Controlled at 20-40℃ / hour, during the water cooling process, accurately control the water flow and temperature T 水 , water temperature T 水 Keep the temperature between 20-30℃ to avoid cracks on the surface of the manganese ingot or excessive internal stress due to too fast water cooling speed or too low water temperature.

10. The method for preparing low-nitrogen manganese metal ingots using argon according to claim 1, characterized in that: The post-processing of the S4 manganese metal ingot also includes the following steps: S401, slag removal preparation; After the manganese ingot is cooled to room temperature, it is taken out of the mold and prepared for slag removal. Before slag removal, the manganese ingot is visually inspected to see if there are any obvious surface defects. If there are any defective manganese ingots, they need to be marked and handled separately. At the same time, the appropriate slag removal method and equipment are selected according to the surface condition and impurity type of the manganese ingot. S402, slag removal operation; Mechanical slag removal efficiency formula: If the impurities on the surface of the manganese ingot are mainly loose slag and oxides, mechanical slag removal equipment can be used for treatment. The mechanical slag removal equipment can use a rotating scraper, a high-pressure air purge device or a combination of the two. Suppose the rotating scraper speed is n 刮刀 , then n 刮刀 =50+50×y rpm, where y is the scraper speed adjustment coefficient, 0≤y≤1, and the high-pressure air purge pressure is P 空气 ,but Where z is the air pressure adjustment factor; S403, crushing operation; After completing the slag removal operation on the low-nitrogen manganese ingot, the crusher is controlled to crush the low-nitrogen manganese ingot. The crushed low-nitrogen manganese ingot is screened by screening equipment to remove particles that do not meet the particle size requirements. After multiple crushing and screening operations, low-nitrogen manganese ingots that meet the requirements are finally obtained.

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