Smelting reduction device for vanadium-containing ferrophosphorus gradient separation and recycling system and method

Abstract

The invention provides a smelting reduction device for vanadium-containing ferrophosphorus gradient separation and a recycling system and method, and belongs to the technical field of metallurgy and resource recycling. The system comprises a smelting furnace which is internally provided with a CO2 injection system leading to a molten pool and is used for injecting CO2 into the molten pool; the integrated alloy hardening and tempering system is used for on-line regulation and alloying of molten iron components and direct production of mother alloy; the gas inlet system is used for guiding high-temperature flue gas of the smelting furnace into an external roasting kiln, and the feeding preheating system is used for guiding low-temperature waste heat in the system into an external hydrothermal reaction kettle. A smelting furnace integrating CO2 weak oxidation stirring, an integrated alloy tempering system and a smelting reduction device and a tailing recycling system of a cross-process heat energy coupling pipeline are constructed, residual phosphorus is deeply removed, and meanwhile alloy components are precisely regulated and controlled to prepare the stainless steel mother alloy; waste heat of the high-temperature flue gas and the medium-low-temperature flue gas is recycled for roasting vanadium extraction and hydrothermal dephosphorization procedures in a stepped mode, and high-valued utilization of substances and closed-loop utilization of energy are achieved.

Description

Technical Field

[0001] This invention relates to the fields of metallurgy and resource recycling technology, and in particular to a molten reduction apparatus, resource recovery system and method for the cascade separation of vanadium-containing phosphorus iron. Background Technology

[0002] After vanadium-containing ferrophosphorus is processed using the "hydrothermal pre-dephosphorization-low-temperature roasting for vanadium extraction" process, a large amount of tailings rich in iron, chromium, and nickel will be generated. How to achieve efficient and high-value utilization of these tailings is the final step in the entire resource recovery process and is the core factor determining its economic and environmental benefits.

[0003] Currently, the mainstream disposal method for this type of tailings is to return it to conventional steelmaking furnaces for reuse or as raw material for ironmaking, but this model has significant drawbacks: 1) Residual phosphorus is difficult to remove deeply, thus affecting the final quality of molten steel; 2) Valuable elements such as chromium and nickel have not been able to achieve precise alloying with controllable composition, and their value has not been maximized; 3) The energy consumption of the tailings smelting process is relatively high, and the generated high-temperature flue gas containing CO is mostly directly emitted or simply treated, resulting in significant energy waste and further increase in carbon emissions.

[0004] For example, when traditional electric arc furnaces process this type of tailings, a strong oxidizing atmosphere is required for dephosphorization, which easily causes valuable metals such as chromium and vanadium to be oxidized and lost into the slag (i.e., the "chromium and vanadium preservation problem"). Furthermore, the thermal energy of each process is independent, and no cross-process energy coupling network has been established, resulting in high total system energy consumption and carbon emissions. The "steel-chemical co-production" technology currently being explored in the steel industry focuses on improving energy efficiency and reducing carbon emissions through the recycling of waste gas, waste heat, and byproducts such as CO2. However, combining this concept with the deep resource utilization of specific materials such as vanadium-phosphorus iron tailings to form targeted, specialized equipment innovation solutions is currently lacking. Summary of the Invention

[0005] In view of this, in order to solve the problem of how to achieve efficient and high-value utilization of the tailings, this invention provides a molten reduction device, resource utilization system and method for the cascade separation of vanadium-phosphorus-iron. It constructs a molten reduction device and tailings resource utilization system that integrates a CO2 weak oxidation stirring smelting furnace, an integrated alloy tempering system and cross-process thermal energy coupling pipelines. While deeply removing residual phosphorus, it precisely controls the alloy composition to prepare stainless steel master alloy, and the high-temperature flue gas waste heat is cascaded back to the preceding roasting vanadium extraction and hydrothermal dephosphorization processes, realizing high-value utilization of materials and closed-loop energy utilization.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a molten reduction apparatus for the vanadium-phosphorus-iron graded separation, comprising: The smelting furnace is equipped with a CO2 injection system that leads to the molten pool. CO2 is injected into the molten pool to selectively oxidize residual phosphorus by utilizing its weak oxidizing properties. An integrated alloy quenching and tempering system is connected to the outlet of the smelting furnace and is used for online control and alloying of molten iron composition to directly produce master alloys. The thermal coupling pipeline includes a first flue gas pipeline and a second flue gas pipeline. The first flue gas pipeline connects the high-temperature flue gas outlet of the smelting furnace to the air intake system of the roasting kiln of the preceding roasting and vanadium extraction unit. The second flue gas pipeline connects the flue gas outlet of the roasting kiln of the preceding roasting and vanadium extraction unit or a bypass of the first flue gas pipeline to the feed preheating system of the external hydrothermal reactor.

[0007] Preferably, the CO2 injection system includes a plurality of CO2 injection guns disposed on the side wall, top, or bottom of the furnace body.

[0008] Preferably, the CO2 spray gun is a multi-hole spray gun that can be raised, lowered, and has an adjustable angle, with a CO2 spray intensity of 1-50 Nm. 3 / (t·h).

[0009] Preferably, the integrated alloy quenching and tempering system includes: An online composition analyzer is used for real-time composition analysis of the flowing molten iron; The precision feeding device adds the required alloying elements to the molten iron flow based on the composition analysis results.

[0010] Preferably, it further includes: An electromagnetic stirrer uses an electromagnetic field to promote the uniform dissolution of alloying elements, avoid component segregation, and ensure the stability of the final product composition.

[0011] Preferably, the online component analyzer is a laser-induced breakdown spectrometer or a mobile direct-reading spectrometer, and the precision feeding device is a hopper with weighing and rate control. The precision feeding device automatically adds one or more of nickel, ferrochrome, and carbonaceous reducing agents according to the feedback signal from the online component analyzer.

[0012] Preferably, the thermal coupling pipeline is further provided with a first heat exchanger and a second heat exchanger; The first heat exchanger is installed on the first flue gas duct and is used to transfer the waste heat of the flue gas to the combustion air or materials of the kiln. The second heat exchanger is installed on the second flue gas duct and is used to transfer the waste heat of the outlet flue gas from the roasting kiln of the preceding vanadium extraction unit to the feed slurry of the hydrothermal reactor.

[0013] Secondly, the present invention provides a resource utilization system for vanadium-phosphorus-iron tailings, including the above-mentioned melting and reduction device, and a hydrothermal pre-dephosphorization unit and a low-temperature roasting vanadium extraction unit connected in sequence. The hydrothermal pre-dephosphorization unit is used to dephosphorize vanadium-containing iron phosphorus raw materials and output dephosphorized slag. The low-temperature roasting vanadium extraction unit is used to roast, leach and recover vanadium from the dephosphorization slag, and output vanadium extraction tailings. The feed inlet of the molten reduction device is used to receive the vanadium extraction tailings.

[0014] Preferably, the low-temperature roasting vanadium extraction unit includes a rotary kiln, and the first flue gas duct is connected to the burner or preheating section of the rotary kiln. The hydrothermal pre-dephosphorization unit includes a high-pressure reactor and a feed pipeline, and the second flue gas pipeline is coupled to the feed pipeline through the second heat exchanger.

[0015] Thirdly, the present invention provides a method for treating vanadium-containing ferrophosphorus tailings using the above-mentioned vanadium-containing ferrophosphorus tailings resource utilization system, comprising the following steps: Step S1: Add the vanadium extraction tailings from the low-temperature roasting vanadium extraction unit into the smelting furnace for melting; Step S2: Inject CO2 gas into the molten pool through the CO2 injection system to control the smelting temperature at 1500-1600℃; Step S3: After smelting, the melt is transferred to the integrated alloy quenching and tempering system. Through online composition detection and element addition, the stainless steel master alloy is obtained through quenching and tempering. Step S4: The high-temperature flue gas generated in steps S2 and S3 is introduced into the preceding vanadium extraction unit through the thermal coupling pipeline; Step S5: The low-temperature flue gas generated in step S4 is introduced into the preceding hydrothermal pre-dephosphorization unit through the thermal coupling pipeline for waste heat utilization.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Advantages of High-Value Recovery and Precise Composition Control: This invention utilizes an integrated alloy tempering system in synergy with a CO2-based weak-oxidation smelting furnace to directly temper vanadium-phosphorus iron vanadium extraction tailings into a stainless steel master alloy with stable and controllable composition, achieving high-value recovery of valuable elements such as Fe, Cr, and Ni from the tailings. Compared to existing technologies where tailings are merely returned as ordinary steelmaking raw materials, this invention significantly enhances the added value of the tailings. Furthermore, through online composition detection and precise addition of alloying elements, it ensures that the alloy composition consistently meets the standards for stainless steel master alloys, overcoming the technical shortcomings of existing technologies where valuable elements in the tailings are not directionally alloyed and their value is not maximized.

[0017] Advantages of precise dephosphorization and efficient retention of valuable metals: This invention injects CO2 gas into the molten pool of the smelting furnace, utilizing the weak oxidizing properties of CO2 to selectively oxidize residual phosphorus while simultaneously inhibiting the oxidation loss of valuable metals such as Cr and V. This achieves deep removal of residual phosphorus to ≤0.015% and a Cr recovery rate of ≥95%. Compared to the shortcomings of traditional strong oxidizing dephosphorization processes that result in large amounts of Cr and V being oxidized and entering the slag, this invention effectively retains valuable metals while achieving deep dephosphorization, solving the technical challenge of simultaneously achieving "dephosphorization" and "chromium and vanadium retention" in existing technologies.

[0018] Advantages of Cross-Process Thermal Energy Cascade Utilization and Energy Saving and Carbon Reduction: This invention constructs a cross-process thermal energy closed-loop utilization system through thermal energy coupling pipelines: the high-temperature section of the high-temperature flue gas from the smelting furnace is introduced into the preceding low-temperature roasting vanadium extraction unit as supplementary fuel or preheating combustion air; the medium- and low-temperature section preheats the feed slurry of the preceding hydrothermal pre-dephosphorization unit through a heat exchanger, achieving cascaded and efficient utilization of flue gas waste heat. Compared with the energy waste caused by the direct emission or simple treatment of high-temperature flue gas in existing technologies, this invention reduces the overall system energy consumption by more than 20%, contributes 46% carbon emission reduction benefits to the entire process, and solves the technical defects of high energy consumption and large carbon emissions in the tailings smelting process of existing technologies.

[0019] Advantages of end-to-end system synergy and enhanced process barriers: The molten reduction device of this invention serves as the core hub of the vanadium-phosphorus-iron cascade separation process, connecting the entire process of hydrothermal pre-dephosphorization, low-temperature roasting for vanadium extraction, and tailings molten reduction. This achieves a coordinated cycle of material and energy flows, making the entire process an organic whole. Compared to the shortcomings of existing technologies where each process operates independently and system synergy is poor, this invention improves the overall stability and resource utilization of the process system. Attached Figure Description

[0020] Figure 1 This is an overall flowchart of the present invention; Figure 2 This is a schematic diagram of the resource utilization system of the present invention. Detailed Implementation

[0021] This invention provides a molten reduction apparatus for the vanadium-phosphorus-iron graded separation, comprising: The smelting furnace is equipped with a CO2 injection system leading to the molten pool. CO2 is injected into the molten pool to selectively oxidize residual phosphorus due to its weak oxidizing properties. A CO2 lance is installed on the smelting furnace (such as an electric arc furnace). Injecting CO2 into the molten pool utilizes its weak oxidizing properties (compared to oxygen) to selectively oxidize residual phosphorus, generating P2O5 which volatilizes and is removed. Simultaneously, because CO2 has a weak oxidation potential for chromium and vanadium, its loss can be effectively suppressed. The endothermic effect and stirring effect of CO2 injection also precisely and uniformly heat the molten pool, avoiding localized overheating. This achieves precise control of "dephosphorus removal while preserving chromium and vanadium," solving the problems of traditional processes.

[0022] An integrated alloy quenching and tempering system, connected to the outlet of the smelting furnace, is used for online control and alloying of molten iron composition, directly producing master alloys. This system integrates functions such as melt transfer, online rapid composition detection (e.g., LIBS), precise addition of alloying elements (nickel, ferrochrome, etc.), and electromagnetic stirring. The system can adjust the addition amount in real time based on the detection results, ensuring that the final alloy composition (e.g., Cr 18-22%, Ni 8-12%) stably meets the standards for stainless steel master alloys, achieving direct conversion from tailings slag to high-end products.

[0023] The thermal coupling pipeline includes a first flue gas duct and a second flue gas duct. The first flue gas duct connects the high-temperature flue gas outlet of the smelting furnace to the air intake system of an external roasting kiln. The second flue gas duct connects the high-temperature flue gas outlet or a bypass of the first flue gas duct to the feed preheating system of an external hydrothermal reactor. Through a specially designed flue gas duct and heat exchange network, the thermal coupling pipeline utilizes the high-temperature flue gas (rich in CO and sensible heat) generated by the smelting furnace in two stages: the high-temperature portion (>800℃) is directly introduced into the preceding roasting rotary kiln as supplementary fuel and heat source; the medium- and low-temperature portion preheats the slurry required for the preceding hydrothermal reaction through a heat exchanger. This constructs a cross-process "thermal energy closed loop," upgrading single-point energy saving to system-wide energy saving, and is a key equipment guarantee for achieving the 46% carbon emission reduction target for the entire process.

[0024] In this technical solution, CO2 is injected into the molten pool of the smelting furnace through a CO2 injection system. The weak oxidizing properties of CO2 selectively oxidize residual phosphorus in the tailings while simultaneously inhibiting the oxidation of valuable metals such as Cr and V. An integrated alloying and tempering system performs online composition detection and alloying element addition on the molten iron after smelting, directly preparing qualified master alloys. Thermal coupling pipelines introduce the high-temperature flue gas from the smelting furnace into an external roasting kiln and a hydrothermal reactor, achieving cascaded recovery and utilization of waste heat from the flue gas. This is the first time that the integrated system of "dephosphorization-alloying-waste heat utilization" for vanadium-phosphorus iron tailings has been achieved, solving the problems of low high-value utilization rate of tailings, the contradiction between dephosphorization and chromium / vanadium preservation, and waste of flue gas waste heat in existing technologies. It constructs a core device for the synergistic circulation of materials and energy.

[0025] In this invention, the CO2 injection system includes several CO2 nozzles disposed on the sidewalls, top, or bottom of the furnace body, injecting CO2 into the molten pool from different positions. This enhances the stirring effect of the molten pool, expands the contact area between CO2 and molten slag, and improves the selective oxidation dephosphorization efficiency. Compared to single-position injection, multi-position injection results in a more uniform composition and temperature in the molten pool, strengthens the oxidation effect of CO2 on residual phosphorus, further reduces phosphorus content, and minimizes the loss of valuable metals.

[0026] In this invention, the CO2 spray gun is a multi-hole spray gun that can be raised, lowered, and has an adjustable angle, and the CO2 spray intensity is 1-50 Nm.3 / (t·h). A multi-hole spray gun with adjustable height and angle is used. The spray position and angle are dynamically adjusted according to the molten pool level and smelting stage. By controlling the CO2 spray intensity, the oxidation dephosphorization rate and molten pool stirring intensity are precisely controlled. This achieves refined control of the spraying process, adapting to different smelting conditions and ensuring maximum retention of valuable metals such as Cr and V while achieving efficient dephosphorization. This solves the problem of difficulty in balancing dephosphorization efficiency and metal recovery rate with fixed-parameter spraying.

[0027] In this invention, the integrated alloy quenching and tempering system includes: An online composition analyzer is used for real-time composition analysis of the flowing molten iron; The precision feeding device adds the required alloying elements to the molten iron flow based on the composition analysis results.

[0028] An online composition analyzer analyzes the molten iron composition in real time, and a precision feeding device automatically adds alloying elements based on the analysis results, achieving closed-loop control of the molten iron composition and directly producing master alloys that meet standards. This replaces the traditional extensive mode of offline composition analysis and manual addition, shortens the production cycle, ensures the stability of alloy composition, and realizes the direct conversion of tailings into high-value-added master alloys.

[0029] This invention also includes: Electromagnetic stirrers use electromagnetic fields to promote the uniform dissolution of alloying elements, preventing component segregation and ensuring stable composition in the final product. The electromagnetic field generated by the stirrer acts on the molten iron, causing the added alloying elements to dissolve rapidly and uniformly, preventing component segregation and ensuring the consistency of the master alloy composition. This solves the problem of compositional fluctuations caused by uneven dissolution of added alloying elements, further improving the quality stability of the master alloy product and meeting the compositional precision requirements of high-end stainless steel master alloys.

[0030] In this invention, the online composition analyzer is a laser-induced breakdown spectrometer or a mobile direct-reading spectrometer, and the precise feeding device is a hopper with weighing and rate control. The precise feeding device automatically adds one or more of nickel, ferrochrome, and carbonaceous reducing agents based on the feedback signal from the online composition analyzer. The use of a laser-induced breakdown spectrometer or a mobile direct-reading spectrometer enables rapid online detection of the molten iron composition. The precise addition of nickel, ferrochrome, and carbonaceous reducing agents through the hopper with weighing and rate control ensures the accuracy of the alloy element addition. The fast detection speed and high addition accuracy provide equipment support for the precise control of the master alloy composition, avoiding errors and lags inherent in manual operation.

[0031] In this invention, the thermal coupling pipeline is further provided with a first heat exchanger and a second heat exchanger; The first heat exchanger is installed on the first flue gas duct and is used to transfer the waste heat of the high-temperature flue gas from the furnace to the combustion air or materials in the calcining kiln. The second heat exchanger is installed on the second flue gas duct and is used to transfer the waste heat of the outlet flue gas from the roasting kiln of the preceding vanadium extraction unit to the feed slurry of the hydrothermal reactor.

[0032] A first heat exchanger is installed in the first flue gas duct to transfer the waste heat of the high-temperature flue gas to the combustion air or materials in the roasting kiln; a second heat exchanger is installed in the second flue gas duct to transfer the waste heat of the outlet flue gas from the roasting kiln to the feed slurry in the hydrothermal reactor, achieving efficient cascade utilization of the waste heat. Compared to the extensive utilization method of directly introducing flue gas, the addition of heat exchangers improves the waste heat transfer efficiency, further reduces the energy consumption of upstream processes, and enhances the energy-saving and carbon-reduction effect of the entire process.

[0033] like Figure 2 As shown, the present invention provides a resource utilization system for vanadium-phosphorus iron tailings, including the above-mentioned melting reduction device, and a hydrothermal pre-dephosphorization unit and a low-temperature roasting vanadium extraction unit connected in sequence. The hydrothermal pre-dephosphorization unit is used to dephosphorize vanadium-containing iron phosphorus raw materials and output dephosphorized slag. The low-temperature roasting vanadium extraction unit is used to roast, leach and recover vanadium from the dephosphorization slag, and output vanadium extraction tailings. The feed inlet of the molten reduction device is used to receive the vanadium extraction tailings.

[0034] In this technical solution, vanadium-containing ferrophosphorus raw materials are sequentially dephosphorized in a hydrothermal pre-dephosphorization unit and vanadium-extraction in a low-temperature roasting unit. The resulting vanadium-extraction tailings are then fed into a molten reduction unit for high-value processing, forming a complete cascade separation system of "dephosphorization-vanadium extraction-tailings alloying". This achieves the targeted separation and high-value recovery of elements such as P, V, Fe, Cr, and Ni in vanadium-containing ferrophosphorus, solving the problems of low resource utilization and low product added value in existing technologies, and constructing a complete resource recycling chain.

[0035] In this invention, the low-temperature roasting vanadium extraction unit includes a rotary kiln, and the first flue gas duct is connected to the burner or preheating section of the rotary kiln. The hydrothermal pre-dephosphorization unit includes a high-pressure reactor and a feed pipeline, and the second flue gas pipeline is coupled to the feed pipeline through the second heat exchanger.

[0036] The first flue gas duct is connected to the rotary kiln burner or preheating section of the low-temperature roasting vanadium extraction unit, directly providing a heat source for roasting. The second flue gas duct is coupled to the feed pipeline of the hydrothermal pre-dephosphorization unit through a second heat exchanger, preheating the feed slurry and achieving targeted and precise utilization of waste heat. This strengthens the thermal energy synergy between the melting reduction unit and the preceding processes, maximizing the recovery of high-temperature flue gas waste heat, further reducing the overall energy consumption of the entire process, and enhancing the overall system synergy and process barriers.

[0037] like Figure 1-2 As shown, the present invention also provides a method for treating vanadium-containing ferrophosphorus tailings using the above-mentioned vanadium-containing ferrophosphorus tailings resource utilization system, comprising the following steps: Step S1: Add the vanadium extraction tailings from the low-temperature roasting vanadium extraction unit into the smelting furnace for melting; Step S2: Inject CO2 gas into the molten pool through the CO2 injection system to control the smelting temperature at 1500-1600℃; Step S3: After smelting, the melt is transferred to the integrated alloy quenching and tempering system. Through online composition detection and element addition, the stainless steel master alloy is obtained through quenching and tempering. Step S4: The high-temperature flue gas generated in steps S2 and S3 is introduced into the preceding vanadium extraction unit through the thermal coupling pipeline; Step S5: The low-temperature flue gas generated in step S4 is introduced into the preceding hydrothermal pre-dephosphorization unit through the thermal coupling pipeline for waste heat utilization.

[0038] In this technical solution, vanadium extraction tailings are melted in a smelting furnace, dephosphorized by CO2 injection, and then processed into stainless steel master alloys via an integrated alloy tempering system. Simultaneously, the waste heat from the high-temperature flue gas is recycled to the preceding roasting and hydrothermal processes, forming a standardized, end-to-end treatment process. This standardized process ensures the stability and repeatability of tailings treatment, achieving the directional conversion of tailings to stainless steel master alloys and the closed-loop utilization of thermal energy, providing a replicable technical solution for large-scale industrial applications.

[0039] In summary, this invention serves as the final stage of a vanadium-phosphorus iron processing production line, with its feed material being the vanadium extraction tailings from the upstream process (low-temperature roasting vanadium extraction unit). The tailings mainly consist of oxides of Fe, Cr, and Ni, and a small amount of residual phosphorus.

[0040] The core device's workflow is as follows: Vanadium extraction tailings and an appropriate amount of carbonaceous reducing agent are added to the smelting furnace. After smelting begins, the CO2 lance is started at a rate of 1-50 Nm. 3A CO2 injection force of / (t·h) is applied to the molten steel pool. The weak oxidizing property of CO2 preferentially oxidizes and removes residual phosphorus, while its decomposition endothermic (CO2→CO+1 / 2O2) helps stabilize the pool temperature at around 1500-1600℃, preventing excessive oxidation of chromium and vanadium. After smelting, the melt is transferred to an integrated alloy tempering system. An online composition analyzer rapidly analyzes the content of Cr, Ni, C, etc., in the melt. The control system then drives a precise feeding device to add the required ferrochrome, nickel, etc., and after electromagnetic stirring, the melt is cast to obtain a precisely composed stainless steel master alloy ingot.

[0041] Thermal coupling process: High-temperature flue gas (mainly containing CO and CO2, with a temperature of approximately 1200-1500℃) generated during smelting and tempering is recovered through a thermal coupling pipeline. The high-temperature portion is transported to the preceding roasting rotary kiln via the first flue gas pipeline. The CO-rich flue gas can be directly introduced into the kiln as supplementary fuel for combustion, and its sensible heat can also preheat the combustion air in the kiln through the first heat exchanger, thereby significantly reducing the consumption of natural gas or pulverized coal in the roasting process. The flue gas, after being utilized in the roasting kiln, has a lower temperature. Alternatively, a medium-temperature flue gas directly drawn from the smelting furnace, along with the outlet flue gas from the roasting kiln, is transported via the second flue gas pipeline. The waste heat is transferred through the second heat exchanger to the slurry feed pipeline leading to the hydrothermal reactor, preheating the slurry to 70-90℃ and saving the external heating energy required for the hydrothermal reaction.

[0042] Through the above-mentioned equipment integration and system design, the device of the present invention not only completes the resource utilization of tailings itself, but also becomes the hub that connects the upstream and downstream processes and optimizes the energy flow of the entire system, realizing the dual high-efficiency circulation of matter and energy.

[0043] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1 Melting reduction unit for vanadium-phosphorus-iron graded separation Melting furnace and CO2 injection system: In this embodiment, the melting furnace adopts an electric arc furnace design, and multiple sets of CO2 injection lances are installed inside the furnace body. The CO2 injection lances are evenly arranged along the side walls, top, and bottom of the furnace body to ensure that CO2 gas is uniformly injected into the molten pool. The CO2 injection intensity is set at 1-50 Nm. 3 Within the range of / (t·h), the specific value can be adjusted according to the liquid level of the molten pool and the requirements of the oxidation reaction. The weak oxidizing property of CO2 selectively oxidizes phosphorus (P), generating P2O5 which is then volatilized and removed. Because CO2 has a weak oxidizing effect on chromium (Cr) and vanadium (V), over-oxidation of these two precious metals is avoided, thus protecting their effective recovery. Furthermore, the endothermic effect of CO2 decomposition helps stabilize the molten pool temperature, preventing localized overheating and uneven reaction.

[0045] Integrated Alloy Quenching and Tempering System: This device also includes an integrated alloy quenching and tempering system, connected to the outlet of the smelting furnace. The system precisely controls the composition of the molten iron through the following steps: Online component analyzer: In this embodiment, the online component analyzer uses a laser-induced breakdown spectrometer (LIBS) or a mobile direct-reading spectrometer to perform real-time component analysis on the flowing molten iron, detecting elements including Cr, Ni, C, etc.

[0046] Precision feeding device: Based on the composition analysis results, the precision feeding device automatically adds alloying elements (such as nickel, ferrochrome, carbonaceous reducing agents, etc.). The feeding device is equipped with weighing and rate control functions to ensure the accurate addition of alloying elements, thereby stabilizing the composition of the molten iron.

[0047] Electromagnetic stirrer: To ensure uniform dissolution of alloying elements in the melt and avoid component segregation, an electromagnetic stirrer is used in this embodiment. The electromagnetic field can uniformly dissolve alloying elements, ensuring the quality stability of the final alloy.

[0048] Thermal coupling pipeline and waste heat recovery system: In this embodiment, the thermal coupling pipeline consists of a first flue gas duct and a second flue gas duct. First flue gas duct: The high-temperature flue gas from the smelting furnace is transported through the first flue gas duct to the roasting kiln of the preceding vanadium roasting unit. The sensible heat of the high-temperature flue gas (temperature approximately 1200-1500℃) is used to preheat the combustion air or materials in the roasting kiln, and heat exchange occurs through the first heat exchanger, thereby reducing energy consumption during the roasting process.

[0049] Second flue gas duct: The second flue gas duct is connected to the outlet flue gas of the roasting kiln or a bypass of the first flue gas duct. Through the second heat exchanger, the waste heat of the outlet flue gas of the roasting kiln is transferred to the feed slurry of the hydrothermal reactor, preheating the slurry to 70-90℃, thereby saving the external heating energy required for the hydrothermal reaction.

[0050] Example 2 Vanadium-phosphorus-iron tailings resource utilization system System Composition: In this embodiment, the vanadium-phosphorus iron tailings resource utilization system includes the above-mentioned melting reduction device, a hydrothermal pre-dephosphorization unit and a low-temperature roasting vanadium extraction unit connected in sequence. Hydrothermal pre-dephosphorization unit: This unit includes a high-pressure reactor for hydrothermal reaction of vanadium-containing iron phosphate raw materials to remove phosphorus (P). After processing, the dephosphorized slag is output and prepared for downstream low-temperature roasting vanadium extraction unit.

[0051] Low-temperature roasting vanadium extraction unit: This unit uses a rotary kiln to roast and leach the dephosphorization slag to recover vanadium and convert it into vanadium extraction tailings. These tailings are then sent to a smelting furnace for further resource recovery.

[0052] Smelting and Alloying: The vanadium extraction tailings from the low-temperature roasting vanadium extraction unit are added to the smelting furnace and melted together with an appropriate amount of carbonaceous reducing agent. During this process, CO2 gas is injected into the molten pool through a CO2 injection system, and the temperature is controlled at 1500-1600℃. The weak oxidizing properties of CO2 can preferentially remove residual phosphorus while avoiding the oxidation loss of precious metals such as chromium and vanadium. The molten iron after smelting enters an integrated alloying and tempering system. The composition of the molten iron is monitored in real time using an online composition analyzer, and the amount of alloying elements (such as nickel and chromium) added is adjusted according to the test results to ensure that the final product meets the composition standards of the stainless steel master alloy.

[0053] Heat recovery: High-temperature flue gas generated during the smelting process is recovered and reused through a heat coupling pipeline. First flue gas duct: Through the first flue gas duct, high-temperature flue gas is introduced into the calcining rotary kiln to provide a heat source for combustion inside the kiln, while reducing external fuel consumption.

[0054] Second flue gas duct: After the low-temperature flue gas is processed by the second heat exchanger, the residual heat is transferred to the slurry in the hydrothermal reactor to complete the preheating process of the slurry and save the external heating energy required for the hydrothermal reaction.

[0055] Example 3 Specific methods for processing vanadium-containing ferrophosphorus using this system Processing steps: Step S1: Add the vanadium extraction tailings from the low-temperature roasting vanadium extraction unit and the carbonaceous reducing agent to the smelting furnace.

[0056] Step S2: CO2 gas is injected into the molten pool through a CO2 injection system, and the smelting temperature is maintained at 1500-1600℃ to selectively remove phosphorus.

[0057] Step S3: After smelting, the melt enters the integrated alloy tempering system for composition control. Through online composition detection and precise addition of alloying elements, a standard-compliant stainless steel master alloy is produced.

[0058] Step S4: The generated high-temperature flue gas is introduced into the preceding vanadium extraction unit through a thermal coupling pipeline for further heat recovery.

[0059] Step S5: The low-temperature flue gas is introduced into the hydrothermal pre-dephosphorization unit through the second flue gas duct for waste heat utilization.

[0060] The following examples illustrate this point.

[0061] Example 4: Targeted treatment of high-phosphorus-content vanadium-phosphorus iron tailings For high-phosphorus vanadium-containing ferrophosphate tailings with a phosphorus content ≥0.8%, this product enhances dephosphorization while ensuring chromium and vanadium recovery rates, and is suitable for the stringent composition requirements of high-end stainless steel master alloys.

[0062] Smelting and Dephosphorization Control: High-phosphorus vanadium extraction tailings and carbonaceous reducing agent are added to the smelting furnace at a ratio of 100:8. The CO2 injection system is started, using a combination of multi-hole injection lances at the bottom and side walls of the furnace. The injection intensity is adjusted to 35-50 Nm. 3 / (t·h), the smelting temperature is controlled at 1500℃; the CO2 injection rate is adjusted in real time by online oxygen content monitoring to achieve deep oxidation and removal of phosphorus.

[0063] Precise alloying adaptation: The integrated alloying and tempering system adopts dual-component online composition detection (laser-induced breakdown spectrometer + mobile direct-reading spectrometer) to detect the content of Cr, Ni, P and C elements in real time and synchronously; in view of the slightly high chromium loss of high phosphorus tailings, the precision feeding device automatically adds low phosphorus ferrochrome (Cr≥99%, P≤0.008%), and increases the stirring power to 12kW through electromagnetic stirrer to ensure uniform diffusion of alloying elements.

[0064] Waste heat is utilized in stages: the high-temperature flue gas of 1400-1500℃ generated by smelting is directly introduced into the burner section of the roasting rotary kiln through the first flue gas pipeline, replacing 30% of the natural gas fuel; the 600-700℃ flue gas after being utilized by the roasting kiln is used by the regenerative heat exchanger of the second flue gas pipeline to preheat the feed slurry of the hydrothermal pre-dephosphorization unit to 90-95℃, further improving the waste heat recovery efficiency.

[0065] Phosphorus in the tailings is removed to below 0.012%, Cr recovery rate is ≥96%, and Ni recovery rate is ≥98%; the composition of the prepared stainless steel master alloy meets the 304 stainless steel standard (Cr 18.2-19.5%, Ni 8.5-9.2%, P≤0.015%); fuel consumption in the roasting process is reduced by 32%, and preheating energy consumption in the hydrothermal process is reduced by 40%.

[0066] Example 5 Optimization of thermal energy coupling system based on heat storage heat exchange To address the problem of insufficient waste heat recovery efficiency in traditional heat exchangers, the heat exchange structure of the thermal coupling pipeline is optimized to improve the cascade utilization efficiency of flue gas waste heat and further reduce the overall energy consumption of the process.

[0067] Heat exchange structure upgrade: The first heat exchanger of the first flue gas duct is replaced with a regenerative ceramic heat exchanger, increasing the heat exchange area to 1.5 times the original; the second flue gas duct adopts a spiral wound heat exchanger to increase the contact area and heat exchange time between the flue gas and the feed slurry.

[0068] Flue gas diversion and control: A temperature control valve is installed in the first flue gas pipeline. When the flue gas temperature of the smelting furnace is ≥1300℃, it is directly introduced into the burner of the roasting rotary kiln. When the temperature is 1000-1300℃, the combustion air of the roasting kiln is preheated to 800-900℃ through a regenerative heat exchanger. All medium and low temperature flue gas (400-600℃) is introduced into a spiral wound heat exchanger to preheat the hot feed slurry.

[0069] System linkage control: Establish a linkage control model between the thermal energy coupling system and the preceding process, and automatically adjust the flue gas split ratio and the operating parameters of the heat exchanger according to the temperature requirements of the roasting kiln and the preheating target of the hydrothermal slurry.

[0070] The utilization rate of waste heat from high-temperature flue gas has increased from 65% to 82%, and the utilization rate of waste heat from medium and low-temperature flue gas has increased from 50% to 75%. The overall energy consumption of the entire process has been further reduced by about 8-10%, and the carbon emission reduction ratio has been increased to about 46%. The temperature stability of the roasting kiln has been improved by 15%, and the reaction cycle of the hydrothermal pre-dephosphorization unit has been shortened by 10%.

[0071] Example 6 Multimetal recovery of complex vanadium-phosphorus-iron tailings containing molybdenum and tungsten For complex vanadium-containing ferrophosphate tailings containing Mo (0.2-0.5%) and W (0.1-0.3%), the simultaneous recovery and targeted alloying of multiple valuable metals can be achieved, expanding the application areas of the products.

[0072] Selective dephosphorization and metal retention control: Adjust the spray gun angle of the CO2 injection system so that the side wall spray gun is tilted at 45° towards the center of the molten pool, and the bottom spray gun is vertically upward, with the injection intensity controlled at 20-30 Nm. 3 / (t·h), the smelting temperature is maintained at 1520-1550℃; by controlling the weak oxidizing atmosphere of CO2, dephosphorization is preferentially oxidized, while the oxidation loss of Mo and W is suppressed.

[0073] Multi-element precision alloying: The integrated alloy quenching and tempering system adds an online detection module for Mo and W elements, and the precision feeding device adds a special silo for ferromolybdenum and ferrotungsten. The addition amount is automatically adjusted according to the content of Mo and W in the tailings, and the composition of the master alloy is controlled to meet the standard of molybdenum-containing stainless steel (Cr 17-18%, Ni 8-9%, Mo 2-3%, W 0.5-1%).

[0074] Adaptive thermal coupling: Since the complex tailings smelting flue gas contains a small amount of Mo and W oxides, a ceramic filter device is added to the first flue gas pipeline to remove dust and metal oxides in the flue gas before it is introduced into the roasting and vanadium extraction unit; the second flue gas pipeline maintains the original heat exchange structure to ensure the preheating effect of hydrothermal slurry.

[0075] P was removed to 0.013%, Cr recovery rate ≥95%, Mo recovery rate ≥92%, and W recovery rate ≥90%; the prepared molybdenum-containing stainless steel master alloy met the 316LMo standard requirements; the dust content after flue gas purification was ≤10mg / Nm³. 3 This is to avoid contaminating the vanadium extraction unit during roasting.

[0076] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A molten reduction apparatus for the vanadium-phosphorus-iron graded separation, characterized in that, include: The smelting furnace is equipped with a CO2 injection system that leads to the molten pool. CO2 is injected into the molten pool to selectively oxidize residual phosphorus by utilizing its weak oxidizing properties. An integrated alloy quenching and tempering system is connected to the outlet of the smelting furnace and is used for online control and alloying of molten iron composition to directly produce master alloys. The thermal coupling pipeline includes a first flue gas pipeline and a second flue gas pipeline. The first flue gas pipeline connects the high-temperature flue gas outlet of the smelting furnace to the air intake system of the roasting kiln of the preceding roasting and vanadium extraction unit. The second flue gas pipeline connects the flue gas outlet of the roasting kiln of the preceding roasting and vanadium extraction unit or a bypass of the first flue gas pipeline to the feed preheating system of the external hydrothermal reactor.

2. The molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to claim 1, characterized in that, The CO2 injection system includes several CO2 injection guns installed on the side wall, top, or bottom of the furnace body.

3. The molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to claim 2, characterized in that, The CO2 spray gun is a multi-hole spray gun that can be raised, lowered, and has an adjustable angle, with a CO2 spray intensity of 1-50 Nm. 3 / (t·h).

4. The molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to claim 1, characterized in that, The integrated alloy quenching and tempering system includes: An online composition analyzer is used for real-time composition analysis of the flowing molten iron; The precision feeding device adds the required alloying elements to the molten iron flow based on the composition analysis results.

5. A molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to claim 4, characterized in that, Also includes: An electromagnetic stirrer uses an electromagnetic field to promote the uniform dissolution of alloying elements, avoid component segregation, and ensure the stability of the final product composition.

6. A molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to claim 4, characterized in that, The online component analyzer is a laser-induced breakdown spectrometer or a mobile direct-reading spectrometer, and the precision feeding device is a hopper with weighing and rate control. The precision feeding device automatically adds one or more of nickel, ferrochrome, and carbonaceous reducing agents according to the feedback signal from the online component analyzer.

7. A molten reduction apparatus for the vanadium-phosphorus-iron graded separation according to any one of claims 1-6, characterized in that, The thermal coupling pipeline is also equipped with a first heat exchanger and a second heat exchanger. The first heat exchanger is installed on the first flue gas duct and is used to transfer the waste heat of the flue gas to the combustion air or materials of the kiln. The second heat exchanger is installed on the second flue gas duct and is used to transfer the waste heat of the outlet flue gas from the roasting kiln of the preceding vanadium extraction unit to the feed slurry of the hydrothermal reactor.

8. A resource utilization system for vanadium-phosphorus-iron tailings, characterized in that, include: The melting reduction apparatus according to any one of claims 1 to 7, and the hydrothermal pre-dephosphorization unit and the low-temperature roasting vanadium extraction unit connected in sequence; The hydrothermal pre-dephosphorization unit is used to dephosphorize vanadium-containing iron phosphorus raw materials and output dephosphorized slag. The low-temperature roasting vanadium extraction unit is used to roast, leach and recover vanadium from the dephosphorization slag, and output vanadium extraction tailings. The feed inlet of the molten reduction device is used to receive the vanadium extraction tailings.

9. A resource utilization system for vanadium-phosphorus-iron tailings according to claim 8, characterized in that, The low-temperature roasting vanadium extraction unit includes a rotary kiln, and the first flue gas duct is connected to the burner or preheating section of the rotary kiln. The hydrothermal pre-dephosphorization unit includes a high-pressure reactor and a feed pipeline, and the second flue gas pipeline is coupled to the feed pipeline through the second heat exchanger.

10. A method for treating vanadium-containing ferrophosphorus tailings using the resource recovery system of claim 8 or 9, characterized in that, Includes the following steps: Step S1: Add the vanadium extraction tailings from the low-temperature roasting vanadium extraction unit into the smelting furnace for melting; Step S2: Inject CO2 gas into the molten pool through the CO2 injection system to control the smelting temperature at 1500-1600℃; Step S3: After smelting, the melt is transferred to the integrated alloy quenching and tempering system. Through online composition detection and element addition, the stainless steel master alloy is obtained through quenching and tempering. Step S4: The high-temperature flue gas generated in steps S2 and S3 is introduced into the preceding vanadium extraction unit through the thermal coupling pipeline; Step S5: The low-temperature flue gas generated in step S4 is introduced into the preceding hydrothermal pre-dephosphorization unit through the thermal coupling pipeline for waste heat utilization.

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