Vanadium titano-magnetite smelting method

Abstract

The invention provides a vanadium titano-magnetite smelting method. The preparation method comprises the steps that vanadium titano-magnetite oxidized pellets make contact with reducing gas to be subjected to a reduction reaction, and metallized vanadium-titanium pellets are obtained; the metallized vanadium-titanium pellets are subjected to first melting separation treatment under the carbon adding condition, and iron-containing vanadium-titanium slag and molten iron are obtained; in the first melt separation treatment process, the FeO content in the slag, the alkalinity of the slag, the carbon matching ratio, the melt separation temperature and the melt separation time are controlled; the iron-containing vanadium-titanium slag is subjected to secondary melting separation treatment under the carbon adding condition, and titanium slag and vanadium-containing molten iron are obtained; and in the second melting separation treatment process, the titanium slag layer temperature, the slag-iron boundary layer temperature, the vanadium-containing molten iron layer temperature, the slag tapping temperature, the iron tapping temperature, the carbon matching ratio and the melting separation time are controlled. According to the vanadium titano-magnetite smelting method provided by the invention, three valuable elements of iron, vanadium and titanium can be effectively utilized under the condition of no converter.

Description

Technical Field

[0001] This invention relates to a method for smelting vanadium-titanium magnetite. Background Technology

[0002] Vanadium-titanium magnetite is a polymetallic associated mineral containing vanadium, titanium, iron, and other metals, and is involved in multiple fields such as steel, chemicals, and energy. Currently, the overall level of comprehensive utilization of vanadium-titanium magnetite resources is not high, and vanadium-titanium magnetite smelting processes are mainly divided into two categories. One is the blast furnace-converter smelting process, where titanium enters the blast furnace slag and vanadium is recovered in the converter. This process suffers from problems such as a long process flow, low titanium grade in the slag that cannot be recovered, high carbon emissions, serious pollutant emissions from sintering and coking processes, and a vanadium blowing loss rate in the converter often reaching 5-15%. The other is the direct reduction-electric furnace smelting process, which is currently only used in a few schemes, specifically a rotary hearth furnace coal-based direct reduction-electric furnace smelting process. This process suffers from problems such as low titanium slag grade due to ash content, poor stability, and low efficiency.

[0003] Currently, for non-blast furnace smelting of vanadium-titanium magnetite, the gas-based coal-based direct reduction followed by electric furnace deep reduction method is commonly used to produce vanadium-containing molten iron and titanium slag. The drawback of this method is the need for subsequent converter oxygen blowing for vanadium extraction; given the current need to replace existing capacity, using this route in new steel plants would be too costly.

[0004] Existing technologies disclose a vanadium-titanium magnetite smelting method based on gas-based vertical shaft furnace direct reduction followed by electric furnace smelting. This method first reduces vanadium-titanium oxide pellets in a vertical shaft furnace to obtain hot direct reduced iron (DRI). Then, the hot DRI is sent to a smelting electric furnace for deep reduction to obtain vanadium-containing molten iron and titanium slag. Finally, the vanadium-containing molten iron is sent to a converter for oxygen blowing to extract vanadium. This method has the following problems: Firstly, during deep reduction, excess carbon in the reducing agent easily leads to over-reduction of titanium oxides in the slag, generating high-melting-point substances such as titanium carbonitride, increasing slag viscosity, making slag-iron separation difficult, resulting in high iron content in the slag, high iron loss, and difficulty in controlling the vanadium-titanium orientation. Secondly, this method is not suitable for steel plants without converters. Existing technologies disclose a vanadium-titanium magnetite smelting method based on vertical shaft furnace reduction followed by electric furnace smelting. This method first reduces vanadium-titanium oxide pellets in a vertical shaft furnace to obtain hot direct reduced iron (DRI), then sends the DRI to a smelting electric furnace for processing to obtain vanadium-titanium slag and molten iron. This method suffers from problems such as excessively high temperatures, the need for ferrous oxide in the slag, low iron recovery, increased lining erosion, and difficulty in controlling vanadium ingress into the slag. Specifically: In this method, the smelting temperature is 1500-1700℃, and a mixed gas is used to reduce the vanadium-titanium oxide pellets, inevitably resulting in metallized pellets containing carbon. During smelting, carbon is added to the electrodes, and according to the oxygen potential diagram, vanadium is reduced by carbon and incorporated into the molten iron above 1450℃. Therefore, this method struggles to ensure vanadium ingress into the slag at the smelting temperature of 1500-1700℃. Generally, under these conditions, adding FeO to the slag is necessary to induce vanadium ingress, which not only exacerbates lining erosion but also reduces the vanadium-titanium content in the slag, making vanadium-titanium recovery difficult.

[0005] In summary, there is still a need to research new non-blast furnace smelting methods for vanadium-titanium magnetite that can effectively utilize the three valuable elements of iron, vanadium, and titanium without a converter. Summary of the Invention

[0006] The purpose of this invention is to provide a non-blast furnace smelting technology for vanadium-titanium magnetite that enables the effective utilization of three valuable elements—iron, vanadium, and titanium—without a converter.

[0007] To achieve the above objectives, the present invention provides a method for smelting vanadium-titanium magnetite, wherein the method comprises: Reduction step: Vanadium-titanium magnetite oxide pellets and reducing gas enter the reduction equipment. In the reduction equipment, the vanadium-titanium magnetite oxide pellets come into contact with the reducing gas to carry out a reduction reaction, and metallized vanadium-titanium pellets are obtained. First melting step: The metallized vanadium-titanium pellets are fed into the first melting equipment, where they undergo a first melting treatment under carbon-added conditions to obtain iron-vanadium-titanium slag and molten iron. During the first melting treatment, the FeO content in the slag is controlled at 8-9 wt% (e.g., 8.5 wt%), the slag basicity is 0.8-1.0, the carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is 1.3-1.5, the melting temperature is 1400-1450℃ (e.g., 1450℃), and the melting time is 100-120 min (e.g., 120 min). The second melting step: Iron-vanadium-titanium slag enters the second melting equipment and undergoes a second melting treatment under carbon addition conditions to obtain titanium slag and vanadium-containing molten iron. During the second melting treatment, the temperature of the titanium slag layer is controlled to be greater than that of the slag-iron interface layer, which is greater than that of the vanadium-containing molten iron layer. The temperature of the titanium slag layer inside the second melting equipment is controlled to be 1650-1750℃, the temperature of the slag-iron interface layer is controlled to be 1550-1650℃, and the temperature of the vanadium-containing molten iron layer is controlled to be 1450-1550℃ (e.g., 1500-1550℃). The slag discharge temperature is controlled to be 1630-1670℃ (e.g., 1650℃), and the iron discharge temperature is controlled to be 1450-1470℃. The carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is controlled to be 1.4-1.5, and the melting time is controlled to be 100-120 min.

[0008] In the vanadium-titanium magnetite smelting method provided by this invention, vanadium-titanium magnetite oxide pellets are first reduced with reducing gas to produce metallized vanadium-titanium pellets. Then, the vanadium-titanium magnetite oxide pellets undergo a first smelting under specific conditions to obtain molten iron and iron-containing vanadium-titanium slag. The molten iron can be used for casting high-purity iron and / or steelmaking. The iron-containing vanadium-titanium slag then undergoes a second smelting under specific conditions to obtain titanium slag and vanadium-containing molten iron. The vanadium-containing molten iron can be directly cast into vanadium-containing iron blocks, and the titanium slag is a high-grade titanium slag that can be sold directly or used in the sulfuric acid process to produce titanium dioxide. The vanadium-titanium magnetite smelting method provided by this invention can obtain molten iron with high iron purity, vanadium-containing molten iron with high vanadium grade that can be directly cast into vanadium-containing iron blocks for sale, and high-grade titanium slag that can be sold directly or used in the sulfuric acid process to produce titanium dioxide, achieving effective utilization of the three valuable elements—iron, vanadium, and titanium—without a converter.

[0009] According to a specific implementation of the first aspect, preferably, the method further includes: Preparation steps of oxidized pellets: Vanadium-titanium magnetite green pellets are prepared using vanadium-titanium magnetite powder; after drying, the vanadium-titanium magnetite green pellets are calcined under an oxygen atmosphere to obtain vanadium-titanium magnetite oxidized pellets; More preferably, the diameter of the vanadium-titanium magnetite green pellets is 6-12 mm; More preferably, vanadium-titanium magnetite powder, bentonite, and water are mixed and pelletized to obtain vanadium-titanium magnetite green pellets; even more preferably, based on 100% by weight of vanadium-titanium magnetite powder, the amount of binder is 1-2%, and the amount of water is 7-9%. More preferably, based on the mass of vanadium-titanium magnetite powder as 100%, the content of vanadium-titanium magnetite powder with a particle size of less than 200 mesh (0.074 mm) is not less than 90%; More preferably, the drying temperature is 100-110°C; even more preferably, the drying time is 300-350 min; More preferably, the calcination temperature is 1100-1200℃; even more preferably, the calcination time is 25-35 min; More preferably, the oxygen-rich atmosphere is an air atmosphere; More preferably, based on the total mass of vanadium-titanium magnetite powder as 100%, the vanadium-titanium magnetite powder contains 70-72% TFe, 12-16% TiO2, and 0.5-1.5% V2O5.

[0010] According to a specific embodiment of the first aspect, preferably, in the reduction step, the reducing gas is hydrogen or a mixture of hydrogen and carbon monoxide. More preferably, in the reduction step, the reducing gas is a mixture of hydrogen and carbon monoxide with a molar ratio of hydrogen to carbon monoxide of 1.5-1.7. More preferably, in the reduction step, the reduction temperature is 950-1050℃ and the pressure is 0.6-0.8MPa; More preferably, in the reduction step, the temperature of the reducing gas entering the reduction equipment is 950-1050°C.

[0011] According to a specific implementation of the first aspect, preferably, in the reduction step, the reduction equipment is a hydrogen-based vertical shaft furnace; The hydrogen-based vertical shaft furnace equipment may, but is not limited to, adopt existing hydrogen-based vertical shaft furnace equipment in the industry. Specifically, the hydrogen-based vertical shaft furnace equipment includes a metallurgical vertical shaft furnace, an electric heating furnace for heating reducing gas, and supporting facilities. The supporting facilities include: vertical shaft furnace steel structure frame, pellet feeding facilities, DRI storage and transportation facilities, waste heat recovery facilities, gas circulation pressurization system, dust removal facilities, water treatment facilities, power supply and distribution and electrical drive, etc.

[0012] According to the specific implementation of the first aspect, preferably, in the first melting step, the FeO content in the slag is controlled by adding iron oxide scale.

[0013] According to a specific implementation of the first aspect, preferably, in the first melting step, the alkalinity of the slag is controlled by adding lime (CaO).

[0014] According to a specific implementation of the first aspect, preferably, in the first melting step, carbon addition is achieved by adding at least one of coke, semi-coke, and anthracite.

[0015] According to a specific implementation of the first aspect, preferably, in the first melting step, the temperature of the metallized vanadium-titanium pellets entering the first melting equipment is 600-700°C.

[0016] According to a specific implementation of the first aspect, preferably, in the first melting step, the first melting equipment is a melting electric furnace; In one specific embodiment, the smelting electric furnace is equipped with one or more (two or more) feed ports (e.g., four feed ports), one or more (two or more) tapping ports (e.g., two tapping ports), and one or more (two or more) slag tapping ports (e.g., two slag tapping ports). The furnace chamber of the smelting electric furnace is constructed with an inverted arched bottom to facilitate long-term immersion of molten iron. When the smelting electric furnace is equipped with multiple slag tapping ports, each slag tapping port can discharge slag in turn, for example, changing the slag tapping port every 60 minutes. When the smelting electric furnace is equipped with multiple tapping ports, each tapping port can discharge iron in turn, for example, changing the iron tapping port every 120 minutes. A suspended tapping port opening and closing mechanism is installed next to the iron tapping port and the slag tapping port of the smelting electric furnace for opening or closing the iron tapping port and the slag tapping port. More preferably, in the initial stage of the metallized vanadium-titanium pellets entering the melting furnace, the electrode is inserted into the metallized vanadium-titanium pellet material layer to a depth of 1-1.5 times the electrode diameter, and the electrode submerged arc operation is started. As the electrode arc is ignited, the current begins to increase. When the furnace temperature exceeds 1200°C and iron-containing vanadium-titanium slag and molten iron are formed, open arc operation is adopted. More preferably, an iron-retaining operation is adopted, wherein the amount of iron retained is 30-40% of the total amount of molten iron.

[0017] According to a specific implementation of the first aspect, preferably, the method further includes: First molten iron treatment step: Use the molten iron obtained from the first melting step to cast iron and / or make steel.

[0018] According to a specific implementation of the first aspect, preferably, in the second melting step, carbon addition is achieved by adding at least one of coke, semi-coke, and anthracite.

[0019] According to a specific implementation of the first aspect, preferably, in the second melting step, the second melting equipment is a melting electric furnace.

[0020] According to a specific implementation of the first aspect, preferably, the method further includes: The second molten iron treatment step: cast the vanadium-containing molten iron obtained from the second melting step into vanadium-containing iron blocks.

[0021] According to a specific implementation of the first aspect, preferably, the method further includes: Titanium dioxide preparation steps: Titanium slag obtained from the second melting step can be used to produce titanium dioxide using the sulfuric acid process.

[0022] Traditional coal-based direct reduction methods utilize the solid-solid phase reaction between coal and iron oxide, which suffers from drawbacks such as slow reaction rate, low productivity, low thermal efficiency, high energy consumption, and numerous product impurities. The technical solution provided by this invention first uses reducing gas to reduce vanadium-titanium magnetite oxide pellets, then performs a first smelting under specific conditions to obtain molten iron and iron-vanadium-titanium slag, and then performs a second smelting under specific conditions to obtain titanium slag and vanadium-containing molten iron. Compared with existing technologies, this method offers the following advantages: 1. The technical solution provided by this invention has a clean and environmentally friendly reduction process and a fast reduction rate.

[0023] 2. In the primary smelting process provided by this invention, vanadium does not enter the molten iron. Instead, by controlling the smelting conditions, the metallized vanadium-titanium pellets are smelted into iron-vanadium-titanium slag and molten iron. The molten iron can be used to cast high-purity iron and / or steelmaking. Then, the iron-vanadium-titanium slag is subjected to secondary smelting under specific conditions to obtain titanium slag and vanadium-containing molten iron. The vanadium-containing molten iron can be directly cast into vanadium-containing iron blocks, and the titanium slag is high-grade titanium slag that can be sold directly or used to produce titanium dioxide using the sulfuric acid process. On the one hand, this eliminates the step of building a vanadium-extraction converter, and on the other hand, it achieves the effective utilization of the three valuable elements, iron, vanadium, and titanium. In short, it achieves the effective utilization of the three valuable elements, iron, vanadium, and titanium, without a converter. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0025] In the following examples, unless otherwise stated, all chemical reagents used are commercially available.

[0026] Example 1

[0027] This embodiment provides a method for smelting vanadium-titanium magnetite.

[0028] The vanadium-titanium magnetite smelting method includes: 1. Preparation steps of oxidized pellets: Vanadium-titanium magnetite powder, bentonite and water are mixed in a mass ratio of 92:1:7 to form green vanadium-titanium magnetite pellets; green vanadium-titanium magnetite pellets are prepared using vanadium-titanium magnetite powder; the green vanadium-titanium magnetite pellets are dried at 100℃ for 5 hours and then calcined at 1200℃ for 30 minutes in air atmosphere to obtain vanadium-titanium magnetite oxidized pellets. Among them, the diameter of the green pellets of vanadium-titanium magnetite is 6 mm; Specifically, based on the mass of vanadium-titanium magnetite powder as 100%, the content of vanadium-titanium magnetite powder with a particle size of less than 200 mesh (0.074 mm) is >90%; Of which, based on the total mass of vanadium-titanium magnetite powder as 100%, vanadium-titanium magnetite powder contains 86.97 TFe, 12.53% TiO2, and 0.5% V2O5.

[0029] 2. Reduction step: Vanadium-titanium magnetite oxide pellets at 600℃ and reducing gas (a mixture of hydrogen and carbon monoxide with a molar ratio of 1.6:1) at 1000℃ are introduced into a hydrogen-based vertical shaft furnace (reduction equipment). In the hydrogen-based vertical shaft furnace, the vanadium-titanium magnetite oxide pellets are in contact with the reducing gas and undergo a reduction reaction at 0.6MPa and 1000℃ to obtain metallized vanadium-titanium pellets. The hydrogen-based vertical shaft furnace equipment adopts existing hydrogen-based vertical shaft furnace equipment in the industry. The hydrogen-based vertical shaft furnace equipment includes a metallurgical vertical shaft furnace, an electric heating furnace for heating reducing gas, and supporting facilities. The supporting facilities include: vertical shaft furnace steel structure frame, pellet feeding facilities, DRI storage and transportation facilities, waste heat recovery facilities, gas circulation pressurization system, dust removal facilities, water treatment facilities, power supply and distribution and electrical drive, etc.

[0030] 3. First melting step: Metallized vanadium-titanium pellets at 700℃ are fed into the first melting equipment (melting electric furnace). The first melting process is carried out in the first melting equipment under carbon addition conditions to obtain iron-containing vanadium-titanium slag and molten iron. During the first melting process, the FeO content in the slag is controlled at 8.5wt%, the basicity of the slag is 1.0, the carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is 1.5, the melting temperature is 1450℃, and the melting time is 120min. Among these methods, the FeO content in the slag is controlled by adding iron oxide scale. Among these methods, the alkalinity of the slag is controlled by adding lime. Carbon addition is achieved by adding coke. The electric furnace for smelting and separating is equipped with 4 feed ports, 2 tapping ports, and 2 slag ports to achieve continuous charging and unloading. The furnace chamber of the electric furnace for smelting and separating is constructed with an inverted arch bottom. Slag is discharged from each tapping port in turn, and the tapping port is changed every 60 minutes. Iron is discharged from each tapping port in turn, and the tapping port is changed every 120 minutes. Suspended tapping and separating port opening and closing mechanisms are installed next to the tapping and slag ports of the electric furnace for opening or closing the tapping and slag ports. In the initial stage of the vanadium-titanium metallized pellets entering the melting furnace, the electrode is inserted into the vanadium-titanium metallized pellet material layer to a depth of 1.05 times the electrode diameter, and the electrode submerged arc operation is started. As the electrode arc is ignited, the current begins to increase. When the furnace temperature is greater than 1250℃ and iron-containing vanadium-titanium slag and molten iron are formed, the open arc operation is adopted. At the same time as the open arc operation, the iron retention operation is adopted (the amount of iron retained is 35% of the total amount of molten iron).

[0031] 4. Second Melting Step: The iron-vanadium-titanium slag enters the second melting equipment (melting electric furnace), where it undergoes a second melting process under carbon addition conditions to obtain titanium slag and vanadium-containing molten iron. During the second melting process, the temperature of the titanium slag layer is controlled to be greater than that of the slag-iron interface layer, which is greater than that of the vanadium-containing molten iron layer. The internal temperature of the titanium slag layer is controlled at 1700℃, the temperature of the slag-iron interface layer is controlled at 1600℃, and the temperature of the vanadium-containing molten iron layer is controlled at 1500℃. The slag discharge temperature is controlled at 1650℃, the iron discharge temperature is controlled at 1450℃, the carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is controlled at 1.4, and the melting time is controlled at 120 min. Carbon addition is achieved by adding coke.

[0032] 5. First molten iron treatment step: Use the molten iron obtained from the first melting step to cast iron and make steel.

[0033] The second molten iron treatment step: cast the vanadium-containing molten iron obtained from the second melting step into vanadium-containing iron blocks.

[0034] Titanium dioxide preparation steps: Titanium slag obtained from the second melting step can be used to produce titanium dioxide using the sulfuric acid process.

[0035] In the vanadium-titanium magnetite smelting method provided in this embodiment, the metallization rate of the metallized vanadium-titanium pellets is 77%, the iron concentration in the molten iron obtained in the first melting step is 99 wt%, the titanium concentration in the titanium slag obtained in the second melting step is 55 wt%, the vanadium concentration in the vanadium-containing molten iron obtained in the second melting step is 10 wt%, the titanium recovery rate (based on titanium in the titanium slag) is 93%, the iron recovery rate (based on iron in the molten iron and vanadium-containing molten iron) is 94%, and the vanadium recovery rate (based on vanadium in the vanadium-containing molten iron) is 95%.

[0036] Example 2

[0037] This embodiment provides a method for smelting vanadium-titanium magnetite.

[0038] The vanadium-titanium magnetite smelting method includes: 1. Preparation steps of oxidized pellets: Vanadium-titanium magnetite powder, bentonite and water are mixed in a mass ratio of 92:1:7 to form green vanadium-titanium magnetite pellets; green vanadium-titanium magnetite pellets are prepared using vanadium-titanium magnetite powder; the green vanadium-titanium magnetite pellets are dried at 100℃ for 5 hours and then calcined at 1200℃ for 30 minutes in air atmosphere to obtain vanadium-titanium magnetite oxidized pellets. Among them, the diameter of the green pellets of vanadium-titanium magnetite is 8 mm; Of which, based on the total mass of vanadium-titanium magnetite powder as 100%, vanadium-titanium magnetite powder contains 86.97 TFe, 12.53% TiO2, and 0.5% V2O5.

[0039] 2. Reduction step: Vanadium-titanium magnetite oxide pellets at 700℃ and reducing gas (a mixture of hydrogen and carbon monoxide with a molar ratio of 1.6:1) at 1050℃ are introduced into a hydrogen-based vertical shaft furnace (reduction equipment). In the hydrogen-based vertical shaft furnace, the vanadium-titanium magnetite oxide pellets are in contact with the reducing gas and undergo a reduction reaction at 0.7MPa and 1050℃ to obtain metallized vanadium-titanium pellets. The hydrogen-based vertical shaft furnace equipment adopts existing hydrogen-based vertical shaft furnace equipment in the industry. The hydrogen-based vertical shaft furnace equipment includes a metallurgical vertical shaft furnace, an electric heating furnace for heating reducing gas, and supporting facilities. The supporting facilities include: vertical shaft furnace steel structure frame, pellet feeding facilities, DRI storage and transportation facilities, waste heat recovery facilities, gas circulation pressurization system, dust removal facilities, water treatment facilities, power supply and distribution and electrical drive, etc.

[0040] 3. First melting step: Metallized vanadium-titanium pellets at 700℃ are fed into the first melting equipment (melting electric furnace). The first melting process is carried out in the first melting equipment under carbon addition conditions to obtain iron-containing vanadium-titanium slag and molten iron. During the first melting process, the FeO content in the slag is controlled at 8.5wt%, the basicity of the slag is 0.85, the carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is 1.5, the melting temperature is 1450℃, and the melting time is 120min. Among these methods, the FeO content in the slag is controlled by adding iron oxide scale. Among these methods, the alkalinity of the slag is controlled by adding lime. The carbon addition is achieved by adding semi-coke. The electric furnace for smelting and separating is equipped with 4 feed ports, 2 tapping ports, and 2 slag ports to achieve continuous charging and unloading. The furnace chamber of the electric furnace for smelting and separating is constructed with an inverted arch bottom. Slag is discharged from each tapping port in turn, and the tapping port is changed every 60 minutes. Iron is discharged from each tapping port in turn, and the tapping port is changed every 120 minutes. Suspended tapping and separating port opening and closing mechanisms are installed next to the tapping and slag ports of the electric furnace for opening or closing the tapping and slag ports. In the initial stage of the vanadium-titanium metallized pellets entering the melting furnace, the electrode is inserted into the vanadium-titanium metallized pellet material layer to a depth of 1.2 times the electrode diameter, and the electrode submerged arc operation is started. As the electrode arc is ignited, the current begins to increase. When the furnace temperature is greater than 1250℃ and iron-containing vanadium-titanium slag and molten iron are formed, the open arc operation is adopted. At the same time as the open arc operation, the iron retention operation is adopted (the amount of iron retained is 40% of the total amount of molten iron).

[0041] 4. Second Melting Step: The iron-vanadium-titanium slag enters the second melting equipment (melting electric furnace), where it undergoes a second melting process under carbon-added conditions to obtain titanium slag and vanadium-containing molten iron. During the second melting process, the temperature of the titanium slag layer is controlled to be greater than that of the slag-iron interface layer, which is greater than that of the vanadium-containing molten iron layer. The internal temperature of the titanium slag layer is controlled at 1650℃, the temperature of the slag-iron interface layer is controlled at 1550℃, and the temperature of the vanadium-containing molten iron layer is controlled at 1450℃. The slag discharge temperature is controlled at 1650℃, the iron discharge temperature is controlled at 1420℃, the carbon ratio (the mass ratio of added carbon to oxygen in the metallized pellets) is controlled at 1.5, and the melting time is controlled at 120 min. The carbonization is achieved by adding semi-coke.

[0042] 5. First molten iron treatment step: Use the molten iron obtained from the first melting step to cast iron and make steel.

[0043] The second molten iron treatment step: cast the vanadium-containing molten iron obtained from the second melting step into vanadium-containing iron blocks.

[0044] Titanium dioxide preparation steps: Titanium slag obtained from the second melting step can be used to produce titanium dioxide using the sulfuric acid process.

[0045] In the vanadium-titanium magnetite smelting method provided in this embodiment, the metallization rate of the metallized vanadium-titanium pellets is 78%, the iron concentration in the molten iron obtained in the first smelting step is 99.2 wt%, the titanium concentration in the titanium slag obtained in the second smelting step is 58 wt%, the vanadium concentration in the vanadium-containing molten iron obtained in the second smelting step is 11 wt%, the titanium recovery rate (based on titanium in the titanium slag) is 95%, the iron recovery rate (based on iron in the molten iron and vanadium-containing molten iron) is 98%, and the vanadium recovery rate (based on vanadium in the vanadium-containing molten iron) is 92%.

[0046] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for smelting vanadium-titanium magnetite, wherein, The vanadium-titanium magnetite smelting method includes: Reduction step: Vanadium-titanium magnetite oxide pellets and reducing gas enter the reduction equipment. In the reduction equipment, the vanadium-titanium magnetite oxide pellets come into contact with the reducing gas to carry out a reduction reaction, and metallized vanadium-titanium pellets are obtained. First melting step: Metallized vanadium-titanium pellets are fed into the first melting equipment, where they undergo a first melting treatment under carbon addition conditions to obtain iron-vanadium-titanium slag and molten iron. During the first melting treatment, the FeO content in the slag is controlled at 8-9 wt%, the slag basicity at 0.8-1.0, the carbon ratio at 1.3-1.5, the melting temperature at 1400-1450℃, and the melting time at 100-120 min. The second melting step: Iron-vanadium-titanium slag enters the second melting equipment and undergoes a second melting treatment under carbon addition conditions to obtain titanium slag and vanadium-containing molten iron. During the second melting treatment, the temperature of the titanium slag layer is controlled to be greater than that of the slag-iron interface layer, which is greater than that of the vanadium-containing molten iron layer. The internal temperature of the titanium slag layer is controlled at 1650-1750℃, the temperature of the slag-iron interface layer is controlled at 1550-1650℃, and the temperature of the vanadium-containing molten iron layer is controlled at 1450-1550℃. The slag discharge temperature is controlled at 1630-1670℃, the iron discharge temperature is controlled at 1450-1470℃, the carbon ratio is controlled at 1.4-1.5, and the melting time is controlled at 100-120 minutes.

2. The vanadium-titanium magnetite smelting method according to claim 1, wherein, The method also includes: Preparation steps of oxidized pellets: Vanadium-titanium magnetite green pellets are prepared using vanadium-titanium magnetite powder; after drying, the vanadium-titanium magnetite green pellets are calcined under an oxygen atmosphere to obtain vanadium-titanium magnetite oxidized pellets.

3. The vanadium-titanium magnetite smelting method according to claim 2, wherein, The diameter of green vanadium-titanium magnetite pellets is 6-12 mm; and / or The drying temperature is 100-110℃; and / or The roasting temperature is 1100-1200℃; and / or Based on the total mass of vanadium-titanium magnetite powder as 100%, vanadium-titanium magnetite powder contains 70-72% TFe, 12-16% TiO2, and 0.5-1.5% V2O5.

4. The vanadium-titanium magnetite smelting method according to claim 2 or 3, wherein, The preparation of vanadium-titanium magnetite green pellets using vanadium-titanium magnetite powder includes: Vanadium-titanium magnetite powder, bentonite and water are mixed and pelletized to obtain vanadium-titanium magnetite green pellets; Of which, based on 100% by mass of vanadium-titanium magnetite powder, the amount of binder is 1-2% and the amount of water is 7-9%; Of which, based on the mass of vanadium-titanium magnetite powder as 100%, the content of vanadium-titanium magnetite powder with a particle size of less than 200 mesh is not less than 90%.

5. The vanadium-titanium magnetite smelting method according to claim 1, wherein, In the reduction step, the reducing gas is hydrogen or a mixture of hydrogen and carbon monoxide.

6. The vanadium-titanium magnetite smelting method according to claim 5, wherein, In the reduction step, the reducing gas is a mixture of hydrogen and carbon monoxide with a molar ratio of hydrogen to carbon monoxide of 1.5-1.7; and / or In the reduction step, the reduction temperature is 950-1050℃, and the pressure is 0.6-0.8MPa; and / or During the reduction process, the temperature of the reducing gas entering the reduction equipment is 950-1050℃.

7. The vanadium-titanium magnetite smelting method according to claim 1, wherein, In the reduction step, the reduction equipment uses a hydrogen-based vertical shaft furnace; and / or In the first melting step, the first melting equipment is a melting electric furnace; and / or In the second melting step, the second melting equipment is a melting electric furnace.

8. The vanadium-titanium magnetite smelting method according to claim 1, wherein, In the first melting step, the FeO content in the slag is controlled by adding iron oxide scale; and / or In the first melting step, the alkalinity of the slag is controlled by adding lime; and / or In the first melting step, the temperature of the metallized vanadium-titanium pellets entering the first melting equipment is 600-700℃.

9. The vanadium-titanium magnetite smelting method according to claim 1, wherein, In the first melting step, carbon addition is achieved by adding at least one of anthracite, coke, and semi-coke; and / or In the second melting step, carbon is added by adding at least one of coke, semi-coke, and anthracite.

10. The vanadium-titanium magnetite smelting method according to claim 1, wherein, The method also includes: First molten iron treatment step: using the molten iron obtained from the first melting step to cast iron and / or steel; and / or Second molten iron treatment step: Casting the vanadium-containing molten iron obtained from the second melting step into vanadium-containing iron blocks; and / or Titanium dioxide preparation steps: Titanium slag obtained from the second melting step can be used to produce titanium dioxide using the sulfuric acid process.