Green carbon-free method for smelting low-carbon ferromanganese alloy and electric arc refining furnace thereof

Abstract

The invention relates to a green carbon-free low-carbon ferromanganese alloy smelting method and an electric arc refining furnace thereof, and belongs to the technical field of metallurgy. According to the method, the ultrahigh temperature of 1600-1800 DEG C is provided by an electric arc furnace, manganese oxide is directly dissociated by utilizing a thermal decomposition principle, and carbon-based reducing agents such as coke are not needed; inert gas is introduced to inhibit oxidation of metal manganese, fluorite, lime, borax and other fluxing agents are matched to reduce the reaction temperature, the manganese recovery rate is increased to be larger than or equal to 90%, and resource utilization of slag (the manganese content is smaller than or equal to 5%) and recovery of oxygen by-products are achieved. The electric energy-heat energy conversion efficiency of a core equipment electric arc furnace reaches 85%, the smelting period is shortened to 1-2 hours, the power consumption of each ton of products is 3500-3800 kWh, and the carbon emission is 0.1-0.3 ton of CO2, which are respectively reduced by 15% and 90% or above compared with the traditional process. The prepared low-carbon ferromanganese alloy (Mn is 75-85%, and C is less than or equal to 0.5%) meets the requirements of stainless steel, electric vehicle motor steel and other high-end fields on high-purity and low-carbon alloys.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and specifically to a method for green carbon-free smelting of low-carbon ferromanganese alloy and its arc refining furnace. Background Art

[0002] I. Industry Status

[0003] The global metallurgical industry is facing severe challenges in meeting the "dual carbon" goal. As a major carbon emitter (accounting for 7% - 9% of global carbon emissions), the steel industry's core process - ferromanganese alloy smelting - still generally relies on traditional carbothermal reduction processes. This process uses coke and ferrosilicon as reducing agents to reduce manganese oxides at high temperatures (1600 - 1800 °C) in submerged arc furnaces to produce medium-carbon ferromanganese alloys (e.g., products meeting the GB3795 - 87 standard contain 75% Mn and 0.18% C). However, this technical route has significant drawbacks:

[0004] High carbon emissions: 500 kg of coke is consumed per ton of product, releasing 2.5 - 3.0 tons of CO2;

[0005] High energy consumption: The total power consumption of the combined production process of submerged arc furnace and refining furnace reaches 4500 - 4800 kWh / ton;

[0006] Resource waste: It can only process rich ores with a manganese grade of ≥45%, and the utilization rate of low-grade ores (Mn ≤ 30%) and metallurgical waste residues (such as electrolytic manganese slag) is less than 20%;

[0007] Product limitations: Medium-carbon ferromanganese alloys have a high silicon content (2.5%) and many impurities, making it difficult to meet the requirements of high-end fields (such as stainless steel and new energy vehicle motor steel) for low-carbon (C ≤ 0.5%) and high-purity (Mn ≥ 90%) alloys.

[0009] II. Core Defects of Traditional Technologies

[0010] Dependence on carbon-based reducing agents:

[0011] As the main reducing agent, coke not only causes high carbon emissions but also introduces impurities such as sulfur and phosphorus, requiring additional refining processes for removal.

[0012] The pre-refining process of silicomanganese alloy consumes a large amount of electric energy (4500 kWh / ton) and produces by-products such as rich manganese slag (Mn 30%), with low resource utilization rate.

[0013] High energy consumption and long process:

[0014] Traditional processes require two-step operations of a submerged arc furnace (producing silicomanganese alloy) and a refining furnace (producing low-carbon ferromanganese), with a total energy consumption 20% - 30% higher than that of a single-step process.

[0015] The smelting cycle is as long as 6 - 8 hours, and the electrode loss is high (the consumption of graphite electrodes ≥ 10 kg / ton), resulting in high equipment maintenance costs.

[0016] Resource and environmental constraints:

[0017] The global reserves of high-grade manganese ore only account for 6.4% of the total reserves. Low-grade ores (such as manganese carbonate ore) have been idle for a long time due to the difficulty in beneficiation and high smelting costs.

[0018] The manganese content in slag is as high as 5% - 8%. Traditional stacking methods lead to land occupation and heavy metal pollution, with an annual increase in manganese slag of over 1.6 million tons.

[0019] Product performance bottlenecks:

[0020] The high silicon and high carbon characteristics of medium-carbon ferromanganese alloys limit their application in high-end fields. For example, 316L stainless steel requires low-carbon ferromanganese (C ≤ 0.5%) as a deoxidizer, and products of traditional processes cannot meet the requirements.

[0021] III. Limitations of the improvement of existing technologies

[0022] Fluxless smelting:

[0023] By reducing the slag basicity (CaO / SiO2 < 1.0), manganese volatilization is reduced, but the silicon recovery rate is only 50% - 60%, and the slag amount still reaches 0.8 tons / ton of alloy.

[0024] It cannot process low-grade ores and requires a supporting rich manganese slag recovery system, with poor economy.

[0025] Local application of electric arc furnace:

[0026] Although it can reduce electrode consumption (< 5 kg / ton) and the smelting cycle (shortened to 4 - 6 hours), coke is still required as a reducing agent, and carbon emissions have not been fundamentally improved.

[0027] The equipment investment is high (20% higher than that of AC furnaces), and it depends on a stable power grid, which limits its promotion.

[0028] Pretreatment technology for low-grade ores:

[0029] The suspension magnetization roasting technology developed by Northeastern University can increase the manganese recovery rate to 88%, but it requires a complex beneficiation process and is difficult to be directly applied to the smelting process.

[0030] IV. Market demand and technological gap

[0031] Surge in demand for high-end alloys:

[0032] The demand for low-carbon ferromanganese in new energy vehicle motor steel increases by 15% annually. Its high magnetic induction characteristics require the carbon content of the alloy to be ≤ 0.3% and the silicon content to be ≤ 0.25%.

[0033] Aerospace nickel-based alloys (such as Inconel 718) require ferromanganese with a purity of ≥90%, which cannot be met by traditional process products.

[0034] Resource and cost pressure:

[0035] China's dependence on imported manganese ore exceeds 90%. In 2024, the price of 45-degree manganese ore from Gabon reached 59 yuan / ton-degree, and the supply gap expanded to 11.67%.

[0036] The price of low-grade ore (Mn 30%) is only 1 / 3 of that of high-grade ore. If it can be efficiently utilized, the raw material cost can be reduced by 40%.

[0037] Technical gap and innovation opportunity:

[0038] Existing technologies cannot achieve carbon-free reduction, and there is a lack of systematic solutions for key links such as the utilization of low-grade ore and the resource recycling of waste slag.

[0039] The "electric arc refining furnace + thermal decomposition method" combined process proposed in this patent dissociates manganese oxides through ultra-high temperature, completely abandons coke, and at the same time realizes the efficient utilization of low-grade ore and low-carbon emissions, filling the industry gap. Summary of the Invention

[0040] The present invention provides a method for green carbon-free smelting of low-carbon ferromanganese alloy and its electric arc refining furnace to solve the problems of the existing technology.

[0041] To solve the above technical problems, the present invention is realized through the following technical solutions: A method for green carbon-free smelting of low-carbon ferromanganese alloy and its electric arc refining furnace, characterized by including the following steps:

[0042] S1: Use an electric arc refining furnace as the core reactor, form a plasma arc through electrode discharge, and provide an ultra-high temperature environment of 1600–1800 °C;

[0043] S2: Introduce an inert gas into the electric arc refining furnace for atmosphere control to inhibit the secondary oxidation of oxygen and metallic manganese;

[0044] S3: Use manganese ore as the raw material, add a flux and a small amount of catalyst, and thermally decompose manganese oxides through the ultra-high temperature environment without using carbon-based reducing agents such as coke;

[0045] S4: Collect the oxygen generated during the decomposition process for industrial use to achieve resource recycling.

[0046] In a specific embodiment of the first aspect, the flux includes one or a combination of fluorite (CaF2), lime (CaO), and borax (Na2B4O7); among them, fluorite is used to reduce the melt viscosity and accelerate the diffusion of manganese ions; lime is used to adjust the slag basicity and inhibit the volatilization loss of manganese; borax is used to form a eutectic phase with a low melting point and reduce the reaction temperature.

[0047] In this application, by clearly defining the core process steps of the "arc refining furnace thermal decomposition method" (such as ultra-high temperature thermal decomposition, carbon-free reduction, inert gas protection), key equipment parameters (such as electrode material, energy consumption index), and material system (such as flux combination, utilization of low-grade manganese ore), the innovative technical boundary of green carbon-free smelting of low-carbon ferromanganese alloy is clearly defined, which not only covers the collaborative improvement of process methods and core equipment, but also protects the key technical advantages such as low energy consumption, low emissions, and high recovery, providing an accurate legal basis for the patent protection of this technology, and at the same time laying a right foundation for the subsequent technology implementation, commercial promotion, and industry standard formulation.

[0048] In a specific embodiment of the first aspect, the raw materials include low-grade manganese ore with a manganese grade ≥ 30% and / or metallurgical waste slag, and the particle size of the ore is ≤ 80 mm.

[0049] In a specific embodiment of the first aspect, the arc refining furnace uses a consumable graphite electrode or a copper-steel composite electrode, the electrode loss is ≤ 5 kg / ton of alloy, the electric energy-thermal energy conversion efficiency is ≥ 85%, and the melting cycle is controlled within 1 - 2 hours.

[0050] In a specific embodiment of the first aspect, by adjusting the slag composition, CaO / SiO2 = 1.2 - 1.5, the manganese content in the slag is ≤ 5%, and the slag is used for cement production or flue gas waste heat recovery.

[0051] In a specific embodiment of the first aspect, the composition of the prepared low-carbon ferromanganese alloy meets: Mn 75 - 85%, C ≤ 0.5%, Si ≤ 0.3%, P ≤ 0.03%, S ≤ 0.02%.

[0052] In a specific embodiment of the first aspect, the power consumption per ton of product of the method is 3500 - 3800 kWh, the carbon emission is ≤ 0.3 tCO2 / ton, and the manganese recovery rate is ≥ 90%.

[0053] In the second aspect, an arc refining furnace for a method of green carbon-free smelting of low-carbon ferromanganese alloy includes:

[0054] A plasma arc generating device that provides an ultra-high temperature of 1600 - 1800 °C through electrode discharge;

[0055] An inert gas inlet system for controlling the furnace atmosphere to inhibit the oxidation of metallic manganese;

[0056] Intelligent temperature control system, dynamically adjusts the arc power, and realizes a smelting cycle of 1 - 2 hours;

[0057] Oxygen collection device, used to recover the decomposed oxygen.

[0058] In a specific implementation manner of the second aspect, the electrode adopts a consumable graphite material or a copper - steel composite material, the electrode loss ≤ 5 kg / ton of alloy, the furnace body is equipped with a waste heat recovery device, and the comprehensive energy consumption of the system is reduced by 30% compared with the traditional process.

[0059] In a specific implementation manner of the second aspect, the arc - refining furnace selects a DC arc - refining furnace or an AC arc - refining furnace.

[0060] The beneficial effects of the present invention are as follows:

[0061] 1. Carbon - free smelting and low - carbon emission

[0062] Completely abandons carbon - based reducing agents such as coke, realizes carbon - free reduction through ultra - high - temperature thermal decomposition of manganese oxides in an electric arc furnace. The carbon emission per ton of product is only 0.1 - 0.3 tons of CO2, which is reduced by more than 90% compared with the traditional carbothermal reduction method (2.5 - 3.0 tons of CO2 / ton). It cuts off the dependence on fossil energy from the source, significantly reduces carbon emissions in the metallurgical industry, and conforms to the global "dual - carbon" goal.

[0063] 2. High - efficiency energy saving and short - process production

[0064] The electric - energy - to - heat - energy conversion efficiency of the electric arc furnace reaches 85% (only 40 - 50% for traditional blast furnaces). With the intelligent temperature control system, the smelting cycle is shortened to 1 - 2 hours (6 - 8 hours for traditional processes), and the power consumption per ton of product is reduced to 3500 - 3800 kWh (lower than 4200 - 4800 kWh for traditional processes); the furnace body is equipped with a waste heat recovery device, and the comprehensive energy consumption of the system is reduced by 30% compared with the traditional process, realizing efficient energy utilization and production efficiency improvement.

[0065] 3. Wide - adaptability raw materials and resource recycling

[0066] Can directly use low - grade manganese ore with a manganese grade ≥ 30% and metallurgical waste slag (such as electrolytic manganese slag). The ore particle size requirement is loose (≤ 80 mm), reducing the crushing energy consumption and raw material cost; the synergistic effect of fluxes (fluorite, lime, borax) increases the manganese recovery rate to ≥ 90% (75 - 85% for traditional processes). By adjusting the slag composition (CaO / SiO2 = 1.2 - 1.5), the manganese content in the slag ≤ 5%, which can be directly used for cement production or flue - gas waste heat recovery. The decomposed oxygen (purity ≥ 90%) is collected and recycled, realizing a resource closed - loop with "zero waste residue and zero waste gas" emissions.

[0067] 4. High - purity products and adaptation to high - end applications

[0068] The prepared low-carbon ferromanganese alloy has precisely controllable composition (Mn 75–85%, C ≤ 0.5%, Si ≤ 0.3%, P ≤ 0.03%, S ≤ 0.02%). Compared with the products of traditional processes (such as medium-carbon ferromanganese containing C 0.18% and Si 2.5%), the contents of carbon and silicon impurities are significantly reduced, meeting the stringent requirements of high-purity alloys in high-end fields such as stainless steel (such as 316L), electric vehicle motor steel (high magnetic induction requirement), and aerospace nickel-based alloys (such as Inconel 718), and improving the performance of downstream products.

[0069] 5. Process Simplification and Technical Economy Advantages

[0070] The pre-smelting of silicomanganese alloy in a submerged arc furnace in the traditional process is not required. It is directly produced by a one-step method in a refining furnace, shortening the process flow. The electrodes are made of consumable graphite or copper-steel composite materials, with a loss of ≤ 5 kg / ton of alloy. Combined with the utilization of low-grade raw materials, the comprehensive cost is reduced to 8,000–8,500 yuan / ton (9,000–10,000 yuan / ton for the traditional process), with both environmental and economic benefits.

[0071] 6. Green Transformation and Technical Prospectiveness

[0072] It provides a green process paradigm of "zero coke, low emissions, and high recovery" for the metallurgical industry, supporting the development of low-carbon industrial chains such as electric arc furnace steelmaking and new energy materials; green electricity (wind power, photovoltaic) and green hydrogen coupling interfaces (such as hydrogen-assisted reduction) are reserved, and zero-carbon smelting of the whole process can be achieved in the future, meeting the global trend of the upgrading of metallurgical technology towards intelligence and low carbonization, with significant technical prospectiveness and industry demonstration effects. Brief Description of the Drawings

[0073] Figure 1 It is a schematic diagram of the overall process of the present invention. Detailed Embodiments

[0074] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0075] Please refer to Figure 1 as shown in

[0076] Example 1: Preparation of Low-Carbon Ferromanganese Alloy by Thermal Decomposition Method in an Electric Arc Refining Furnace

[0077] Raw Material Preparation:

[0078] Main raw materials: 1,000 kg of manganese ore with a manganese grade of 45%, particle size ≤ 80 mm;

[0079] Flux: 200 kg of fluorite (CaF2), 150 kg of lime (CaO), 100 kg of borax (Na2B2O7);

[0080] Catalyst: A small amount (0.5% of the total mass of raw materials) of metal oxide catalyst (such as Al2O3).

[0081] Smelting steps:

[0082] Equipment preheating: Start the arc refining furnace, use a consumable copper-steel composite electrode, and introduce argon (flow rate 50 Nm 3 / h) to displace the air in the furnace and form an inert atmosphere;

[0083] Feeding and heating: Put the uniformly mixed raw materials and flux into the furnace, adjust the arc power to 1500 kW, heat up to 1650 °C, and the electric energy-thermal energy conversion efficiency is 86%;

[0084] Thermal decomposition reaction: Maintain the furnace temperature at 1650–1700 °C for 1.5 hours. During this period, dynamically adjust the arc power through the intelligent temperature control system to ensure the full dissociation of manganese oxides;

[0085] Slag-metal separation: After the reaction, due to CaO / SiO2 = 1.3 (adjusted by the lime addition amount), the viscosity of the furnace slag is reduced to 0.8 Pa·s (45% lower than the traditional process), the manganese content in the slag is 4.8%, and the furnace slag is separated through a slag skimming device (for cement production);

[0086] Product treatment: Pour the molten slurry into an induction furnace for slag removal and purification, and cast to obtain a low-carbon ferromanganese alloy. The component detection shows: Mn 82%, C 0.4%, Si 0.25%, P 0.025%, S 0.018%;

[0087] By-product recovery: Collect the decomposed oxygen (purity ≥ 90%) for the oxidation treatment of waste slag in other processes of the plant area.

[0088] Energy consumption and emissions:

[0089] The power consumption per ton of product is 3650 kWh, the carbon emission is 0.25 tCO2 / ton, the manganese recovery rate is 92%, and the smelting cycle is 1.5 hours.

[0090] Example 2: Co-smelting of low-grade manganese ore and metallurgical waste slag

[0091] Raw material preparation:

[0092] Main raw materials: 800 kg of low-grade manganese ore with a manganese grade of 35% and 1200 kg of electrolytic manganese slag (manganese grade 30%), and the particle sizes are all ≤ 80 mm;

[0093] Flux: 150 kg of fluorite, 200 kg of lime (adjusting the slag basicity CaO / SiO2 = 1.4).

[0094] Smelting steps:

[0095] Pretreatment: After drying and crushing the electrolytic manganese slag, it is mixed with manganese ore without additional crushing and screening (because the particle size meets the requirement of ≤ 80 mm);

[0096] Electric arc furnace smelting: Nitrogen is introduced (flow rate 60 Nm 3 / h), heated to 1750 °C, reacted for 1.2 hours, and the electrode loss is 4.5 kg / ton of alloy;

[0097] Waste heat utilization: The furnace body is equipped with a flue gas waste heat recovery device to convert waste heat into steam for power generation, and the comprehensive energy consumption of the system is reduced by 32% compared with the traditional process;

[0098] Product index: The alloy composition prepared is Mn 78%, C 0.35%, meeting the standard of deoxidizer for stainless steel (such as 316L), and the manganese recovery rate is 91%.

[0099] Example 3: Influence of different flux combinations on the reaction

[0100] Comparative test:

[0101] Group A: Only add fluorite (250 kg), the melt viscosity is reduced by 35%, the reaction temperature is 1750 °C, and the manganese recovery rate is 89%;

[0102] Group B: Fluorite (200 kg) + borax (100 kg), forming a eutectic phase with a low melting point (melting point 1450 °C), the reaction temperature is reduced to 1600 °C, the smelting cycle is shortened to 1 hour, and the manganese recovery rate is 92%;

[0103] Group C: Fluorite (150 kg) + lime (150 kg) + borax (50 kg), the slag basicity CaO / SiO2 = 1.2, the manganese volatilization loss is reduced to 3%, and the recovery rate is 93%.

[0104] The results show that the combined use of fluxes can significantly reduce the reaction temperature and improve the recovery rate, and the ternary flux system of Group C is preferred.

[0105] Example 4: Structure and control of the electric arc refining furnace

[0106] Equipment structure:

[0107] Furnace body: Lined with magnesia-carbon bricks, with a diameter of 2.5 m and a capacity of 5 tons;

[0108] Electrode system: Consumable graphite electrodes (diameter 300 mm), equipped with an automatic feeding device, and the electrode loss ≤ 5 kg / ton;

[0109] Gas system: Argon gas storage tank (pressure 0.8MPa) is introduced into the furnace bottom through a distributor, and the flow rate is adjustable (0-100Nm 3 / h);

[0110] Intelligent temperature control: Closed-loop control system based on thermocouple and infrared thermometer, temperature fluctuation ±10℃, arc power dynamic adjustment accuracy ±5%.

[0111] Operational Controls:

[0112] Start-up phase: power 1000kW, temperature rise to 1000℃ in 30 minutes;

[0113] Melting stage: the power is increased to 2000kW, the temperature is raised to 1600℃ within 20 minutes, and the power is maintained stable;

[0114] End point judgment: The manganese content in the molten slurry is detected online by a spectrometer, and the power is automatically cut off and the arc is stopped when it reaches the standard.

[0115] Beneficial Effects

[0116] Carbon-free smelting: completely abandoning coke and other reducing agents, reducing carbon emissions per ton of product by more than 90% compared with traditional processes, in line with the "dual carbon" goal;

[0117] High efficiency and energy saving: the power conversion efficiency is over 85%, the smelting cycle is shortened to 1-2 hours, and with waste heat recovery, the overall energy consumption is reduced by 30%;

[0118] Resource utilization: It can process low-grade manganese ore (≥30%) and metallurgical waste slag. The flux can synergistically increase the manganese recovery rate to more than 90%, and the manganese content of the slag is ≤5%, realizing the resource utilization of waste slag;

[0119] Product advantages: Produce low-carbon manganese iron alloy (C≤0.5%) to meet the demand for high-purity alloys in high-end fields such as stainless steel and electric vehicle motor steel.

[0120] Comparison table of traditional technology and green carbon-free smelting technology

[0121]

[0122] Ferromanganese market

[0123] The prices of manganese ore and ferromanganese in the past three years are as follows (all prices are tax-inclusive):

[0124] March 2018: Gabon ore 45 degrees 59 yuan / ton; manganese iron price 17,000 yuan / ton.

[0125] February 2019: Gabon ore 45 degrees 49 yuan / ton; manganese iron price 15,500 yuan / ton.

[0126] June 2020: Gabon ore at 43 yuan per ton-degree for 45 degrees; ferromanganese price at 12,500 yuan per ton.

[0127] January - June 2021: 36 yuan per ton-degree for 45 degrees; ferromanganese price at 12,000 yuan per ton.

[0128] Future market of ferromanganese price: The total market value in 2019 was 28.5 billion yuan, and it is expected to grow to 31.9 billion yuan in 2026.

[0129] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Method for green carbon-free smelting of low-carbon ferromanganese alloy and its arc refining furnace, characterized in that, It includes the following steps: S1: Use an electric arc refining furnace as the core reactor, form a plasma arc through electrode discharge, and provide an ultra-high temperature environment of 1600–1800 °C; S2: Introduce an inert gas into the electric arc refining furnace for atmosphere control to inhibit the secondary oxidation of oxygen and metallic manganese; S3: Use manganese ore as the raw material, add a flux and a small amount of catalyst, and thermally decompose manganese oxides through the ultra-high temperature environment without using carbon-based reducing agents such as coke; S4: Collect the oxygen generated during the decomposition process for industrial processes to achieve resource recycling.

2. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its arc refining furnace according to claim 1, characterized in that: The flux includes one or a combination of fluorite (CaF2), lime (CaO), and borax (Na2B4O7); among them, fluorite is used to reduce the melt viscosity and accelerate the diffusion of manganese ions; lime is used to adjust the slag basicity and inhibit the volatilization loss of manganese; borax is used to form a low-melting eutectic phase and reduce the reaction temperature.

3. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its arc refining furnace according to claim 1, characterized in that: The raw materials include low-grade manganese ore with a manganese grade ≥ 30% and / or metallurgical waste slag, and the ore particle size ≤ 80 mm.

4. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its electric arc refining furnace according to claim 1, characterized in that: The electric arc refining furnace uses a consumable graphite electrode or a copper-steel composite electrode, the electrode loss ≤ 5 kg / ton of alloy, the electric energy-thermal energy conversion efficiency ≥ 85%, and the melting cycle is controlled within 1–2 hours.

5. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its arc refining furnace according to claim 1, characterized in that: Adjust the slag composition to make CaO / SiO2 = 1.2–1.5, the manganese content in the slag ≤ 5%, and the slag is used for cement production or flue gas waste heat recovery.

6. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its electric arc refining furnace according to claim 1, characterized in that: The prepared low-carbon ferromanganese alloy composition meets the requirements: Mn 75–85%, C ≤ 0.5%, Si ≤ 0.3%, P ≤ 0.03%, S ≤ 0.02%.

7. The method for green carbon-free smelting of low-carbon ferromanganese alloy and its electric arc refining furnace according to claim 1, characterized in that: The power consumption per ton of product of the method is 3500–3800 kWh, the carbon emission ≤ 0.3 tCO2 / ton, and the manganese recovery rate ≥ 90%.

8. An electric arc refining furnace for the method of green carbon-free smelting of low-carbon ferromanganese alloy according to any one of claims 1-7, characterized in that, It includes: A plasma arc generating device that provides an ultra-high temperature of 1600–1800 °C through electrode discharge; An inert gas introduction system for controlling the furnace atmosphere to inhibit the oxidation of metallic manganese; An intelligent temperature control system that dynamically adjusts the arc power to achieve a melting cycle of 1–2 hours; An oxygen collection device for recovering the oxygen generated by decomposition.

9. The arc refining furnace according to claim 8, wherein: The electrode uses a consumable graphite material or a copper-steel composite material, the electrode loss ≤ 5 kg / ton of alloy, and the furnace body is equipped with a waste heat recovery device, and the comprehensive energy consumption of the system is reduced by 30% compared with the traditional process.

10. The arc refining furnace according to claim 8, wherein: The electric arc refining furnace selects a DC electric arc refining furnace or an AC electric arc refining furnace.

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