A production system and method for low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag

Abstract

This invention discloses a production system and method for low-carbon molten steel, silicon-vanadium alloy, and titanium-rich slag, belonging to the field of comprehensive utilization technology of vanadium-titanium magnetite. It solves the problems of low iron utilization value, low vanadium recovery rate, and difficulty in titanium recovery in existing technologies. In this system, a gas-based reduction shaft furnace converts vanadium-titanium magnetite oxide pellets with reducing gas into metallized pellets; a primary melting electric furnace, without adding a reducing agent, converts the metallized pellets into low-carbon molten steel and iron-vanadium-titanium slag; a secondary melting electric furnace is used to convert the iron-vanadium-titanium slag and coke into silicon-vanadium alloy and titanium-rich slag. This invention can be used for the smelting of vanadium-titanium magnetite.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of comprehensive utilization of vanadium-titanium magnetite, and particularly relates to a production system and method of low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag. BACKGROUND

[0002] At present, for the comprehensive utilization of vanadium-titanium magnetite, a method of preparing vanadium-containing molten iron by adopting gas-based reduction shaft furnace pre-reduction and electric furnace deep melting separation is usually adopted. The vanadium-containing molten iron is blown with oxygen in a vanadium extraction converter, V is oxidized to V2O5 to form vanadium slag, then the vanadium slag is used to produce vanadium flake, and the molten iron is used for steelmaking.

[0003] However, the iron utilization value in the above method is low, resulting in low iron utilization value of vanadium-titanium magnetite, low vanadium recovery utilization rate and difficulty in recycling and utilizing titanium. SUMMARY

[0004] In view of the above analysis, the application aims to provide a production system and method of low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag, to solve the problems of low iron utilization value of vanadium-titanium magnetite, low vanadium recovery utilization rate and difficulty in recycling and utilizing titanium in the prior art.

[0005] The purpose of the application is mainly achieved through the following technical solutions.

[0006] The application provides a production system of low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag, comprising an oxidized pellet supply unit, a gas-based reduction shaft furnace, a primary melting separation electric furnace and a secondary melting separation electric furnace.

[0007] The oxidized pellet is a vanadium-titanium magnetite oxidized pellet;

[0008] The gas-based reduction shaft furnace is provided with a reducing gas inlet, and the secondary melting separation electric furnace is provided with a coke inlet;

[0009] The oxidized pellet outlet of the oxidized pellet supply unit is connected with the oxidized pellet inlet of the gas-based reduction shaft furnace, the metallized pellet outlet of the gas-based reduction shaft furnace is connected with the metallized pellet inlet of the primary melting separation electric furnace, and the slag outlet of the primary melting separation electric furnace is connected with the slag inlet of the secondary melting separation electric furnace;

[0010] The gas-based reduction shaft furnace is used for converting the vanadium-titanium magnetite oxidized pellet and the reducing gas into metallized pellets; the primary melting separation electric furnace is used for converting the metallized pellets into low-carbon molten steel and iron-vanadium-titanium slag without adding a reducing agent; and the secondary melting separation electric furnace is used for converting the iron-vanadium-titanium slag and the coke into silicon-vanadium alloy and titanium-rich slag.

[0011] Further, the gas-based reduction shaft furnace is connected with the primary melting separation electric furnace through a heat preservation conveying assembly.

[0012] Further, the gas-based reduction shaft furnace is directly connected with the primary melting separation electric furnace.

[0013] Furthermore, the reducing gas inlets include multiple CO inlets and multiple H2 inlets.

[0014] Furthermore, multiple CO inlets are evenly arranged circumferentially along the gas-based reduction shaft furnace, and multiple H2 inlets are evenly arranged circumferentially along the gas-based reduction shaft furnace.

[0015] Furthermore, the ratio of CO import flow to H2 import flow is 11–14:6–9.

[0016] Furthermore, the mass percentage of C in the low-carbon steel molten steel is <0.1%, and the mass percentage of Fe is >99.0%.

[0017] Furthermore, the mass percentage of V in the silicon-vanadium alloy is >3%, and the mass percentage of TiO2 in the titanium-rich slag is >50%.

[0018] Furthermore, the metallization rate of the metallized pellets is 85%–90%.

[0019] The present invention also provides a method for producing low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag, wherein the above-mentioned production system is used to produce low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects.

[0021] A) The production system for low-carbon steel, silicon-vanadium alloy and titanium-rich slag provided by the present invention adopts a gas-based reduction vertical furnace, a primary melting and separation electric furnace and a secondary melting and separation electric furnace to recover iron, vanadium and titanium resources in vanadium-titanium magnetite in a cascade manner, and respectively prepares low-carbon steel, silicon-vanadium alloy and titanium-rich slag, thereby realizing the high-value utilization of iron, vanadium and titanium in vanadium-titanium magnetite.

[0022] B) The production system for low-carbon steel, silicon-vanadium alloy, and titanium-rich slag provided by this invention reduces iron oxide in vanadium-titanium magnetite to iron in the first melting electric furnace. The resulting iron has a low impurity content and can be used to prepare other ultra-pure steels. This is because, on the one hand, SiO2, MnO, and vanadium oxide cannot be reduced by CO and cannot enter the iron, remaining in the slag; on the other hand, CO reduced by gas is difficult to react with metallic iron to form Fe3C, resulting in very low carburization in the metallized pellets. In the second melting electric furnace, coke is added to the iron-vanadium-titanium slag for secondary deep reduction. Based on the principle of selective reduction, the secondary deep reduction reduces iron oxide, vanadium oxide, and some silicon dioxide in the slag into the alloy, thus obtaining a silicon-vanadium alloy. This silicon-vanadium alloy can be used for oxygen blowing to extract vanadium or to replace ferrovanadium alloy. Since iron, vanadium, and some titanium are reduced into the alloy, the remaining slag is titanium-rich slag, from which TiO2 can be further extracted for the production of titanium dioxide.

[0023] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0024] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0025] Figure 1 The structural block diagram of the production system for low-carbon molten steel, silicon-vanadium alloy and titanium-rich slag provided by the present invention.

[0026] Figure label:

[0027] 1-Induction furnace; 2-Gas-based reduction vertical furnace; 3-Gas generator; 4-Primary melting and separation electric furnace; 5-Oxygen-coal lance; 6-Secondary melting and separation electric furnace; 7-Gas riser pipe; 8-Air guide duct; 9-Gas downcomer pipe; 10-First settling chamber; 11-Second settling chamber; 12-Reforming furnace body. Detailed Implementation

[0028] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0029] This invention provides a production system for low-carbon molten steel, silicon-vanadium alloy, and titanium-rich slag. (See also...) Figure 1 The system comprises an oxide pellet supply unit, a gas-based reduction shaft furnace 2, a primary melting electric furnace 4, and a secondary melting electric furnace 6, connected in sequence. The oxide pellets are vanadium-titanium magnetite oxide pellets. The gas-based reduction shaft furnace 2 has a reducing gas inlet, and the secondary melting electric furnace 6 has a coke inlet. The oxide pellet outlet of the oxide pellet supply unit is connected to the oxide pellet inlet of the gas-based reduction shaft furnace 2, the metallized pellet outlet of the gas-based reduction shaft furnace 2 is connected to the metallized pellet inlet of the primary melting electric furnace 4, and the slag outlet of the primary melting electric furnace 4 is connected to the slag inlet of the secondary melting electric furnace 6. The gas-based reduction shaft furnace 2 is used to convert vanadium-titanium magnetite oxide pellets and reducing gas into metallized pellets. The primary melting electric furnace 4 does not add a reducing agent and is used to convert the metallized pellets into low-carbon steel and iron-vanadium-titanium slag. The secondary melting electric furnace 6 is used to convert iron-vanadium-titanium slag and coke into silicon-vanadium alloy and titanium-rich slag.

[0030] Compared with existing technologies, the production system for low-carbon steel, silicon-vanadium alloy and titanium-rich slag provided by the present invention adopts a gas-based reduction vertical furnace 2, a primary melting electric furnace 4 and a secondary melting electric furnace 6 to recover iron, vanadium and titanium resources in vanadium-titanium magnetite in a cascade manner, and respectively prepare low-carbon steel, silicon-vanadium alloy and titanium-rich slag, thereby realizing the high-value utilization of iron, vanadium and titanium in vanadium-titanium magnetite.

[0031] Specifically, in the first melting furnace 4, iron oxide in vanadium-titanium magnetite is reduced to iron. The resulting iron has a low impurity content and can be used to prepare other ultra-pure steels. This is because, on the one hand, SiO2, MnO, and vanadium oxide cannot be reduced by CO and cannot enter the iron, remaining in the slag; on the other hand, CO reduced by gas is difficult to react with metallic iron to form Fe3C, resulting in very low carburization in the metallized pellets. In the second melting furnace 6, coke is added to the iron-vanadium-titanium slag for secondary deep reduction. Based on the principle of selective reduction, the iron oxide, vanadium oxide, and some silicon dioxide in the slag are reduced into the alloy, thus obtaining a silicon-vanadium alloy. This silicon-vanadium alloy can be used for oxygen blowing to extract vanadium or as a substitute for ferrovanadium alloys. Since iron, vanadium, and some titanium are reduced into the alloy, the remaining slag is titanium-rich slag, from which TiO2 can be further extracted for the production of titanium dioxide.

[0032] To reduce carburization during the cooling process of the metallized pellets, the gas-based reduction shaft furnace 2 is connected to the primary melting electric furnace 4 via an insulated conveying assembly, or the gas-based reduction shaft furnace 2 is directly connected to the primary melting electric furnace 4. This allows the metallized pellets to be hot-charged into the electric furnace. Hot charging not only reduces the electric furnace's melting power consumption but also prevents carburization during cooling, resulting in steel with very low carbon content.

[0033] For example, the reducing gases are CO and H2, and accordingly, the reducing gas inlets include multiple CO inlets and multiple H2 inlets.

[0034] In order to improve the uniformity of CO and H2 gas supply, multiple CO inlets are evenly arranged around the circumference of the gas-based reduction vertical furnace 2, and multiple H2 inlets are evenly arranged around the circumference of the gas-based reduction vertical furnace 2.

[0035] To ensure stable operation of the reduction production, the flow rate ratio of CO inlet to H2 inlet is 11–14:6–9. This is because CO reduction of iron is an exothermic reaction, while H2 reduction of iron is an endothermic reaction. With the CO and H2 contents limited to the aforementioned range, the exothermic and endothermic effects of reduction are roughly equal, which is beneficial for stable operation of the reduction production.

[0036] In order to provide CO, the above-mentioned production system also includes a coal gasification unit for CO production, including an intermediate frequency furnace 1 and a gasifier 3 connected in sequence. The gasifier 3 is located above the intermediate frequency furnace 1. The top of the intermediate frequency furnace 1 is open, and the bottom of the gasifier 3 is open. The top opening and the bottom opening are connected to realize the connection between the gasifier 3 and the top of the intermediate frequency furnace 1. The intermediate frequency furnace 1 is provided with a molten iron pool. The gasifier 3 includes a gasifier 3 body and an oxygen-coal lance 5. The gas outlet of the oxygen-coal lance 5 is located in the gasifier 3 body and faces the molten iron pool. The oxygen-coal lance 5 is used to inject a mixture of pulverized coal and slagging agent, as well as O2, into the molten iron pool.

[0037] During implementation, pig iron is loaded into the medium-frequency furnace 1 and melted into molten iron through induction heating, forming a molten iron pool in the medium-frequency furnace 1. Powdered coal, slagging agent and O2 are injected into the molten iron pool through the oxygen-coal injection lance 5. The sulfur in the powdered coal reacts with the slagging agent on the surface of the molten iron pool, fixing the sulfur in the molten iron and slag. O2 and powdered coal react on the surface of the molten iron pool to generate coal gas. The ash in the powdered coal reacts with the slagging agent on the surface of the molten iron pool to generate slag with a lower melting point, thereby producing high-quality coal gas with a lower sulfur content.

[0038] This process, combining O2 and pulverized coal injection for gasification with molten iron pool slag formation, enables online desulfurization during coal gasification, resulting in low-sulfur gas. Specifically, the gasifier 3 is installed above the intermediate frequency furnace 1, which contains a molten iron pool. O2 and pulverized coal are injected into the molten iron pool, where the molten iron and slag absorb the sulfur from the pulverized coal, solidifying it in the molten iron and slag. This produces high-temperature gas with low sulfur content, which can be directly used in a gas-based reduction shaft furnace, eliminating the need for subsequent cooling, desulfurization, and heating processes. This effectively solves the problems of long process flow, high sulfur removal costs, and difficulty in heating coal gas, which require cooling, desulfurization, and heating processes. Meanwhile, since the ash in the pulverized coal (e.g., SiO2 and Al2O3) has a high melting point, the slag-forming agent is injected into the molten iron pool through the oxygen-coal lance 5. The ash reacts with the slag-forming agent to generate slag with a lower melting point. This slag floats on the surface of the molten iron in a liquid state, making it easy to be discharged from the medium-frequency furnace 1.

[0039] In order to perform post-treatment such as dust removal and dehumidification on the produced coal gas, the coal gasification unit for direct reduction in the gas-based reduction shaft furnace also includes a post-treatment utilization unit. The post-treatment unit includes a dust removal component and a coal gas reformer connected in sequence. The inlet of the dust removal component is connected to the outlet of the gasifier 3.

[0040] The gas reformer includes a reformer body 12 and multiple evenly arranged natural gas nozzles. The natural gas nozzles are connected to the inner cavity of the reformer body 12, and the gas outlet of the reformer body 12 is directly connected to the CO inlet. This is because in the gasifier 3, pulverized coal reacts with O2 in an oxidation reaction, inevitably generating CO2 during the process. With the gas reformer, CO2 in the high-temperature coal gas reacts with CH4 in the natural gas to generate CO and H2 (CO2 + CH4 = 2CO + 2H2), reducing the CO2 content in the hot coal gas and increasing the reducing potential of the coal gas. Thus, the gas reformer can reform and regulate the temperature of the coal gas. The reformed coal gas does not need to be cooled, desulfurized, or heated again and can be directly used for direct reduction in a gas-based reduction shaft furnace.

[0041] For example, along the gas flow direction, the reformer body 12 includes an expanding section, a constant diameter section, and a narrowing section connected in sequence. In this way, the gas enters the reformer body 12 from the expanding section, which facilitates the uniform mixing of the gas and natural gas and is beneficial to the reforming reaction. The constant diameter section provides sufficient reaction space for the gas and natural gas to react. The narrowing section can increase the flow rate of the reformed gas and facilitate the gas discharge from the gas reformer. The natural gas nozzle is located in the expanding section at the bottom of the reformer body 12, at a distance of 15-20 cm from the bottom of the reformer body 12. The gas outlet angle of the natural gas nozzle is 15-50° with the tangent of the reformer body 12. The natural gas enters the reformer body 12 in a swirling flow, which facilitates the uniform mixing with the gas, thereby extending the flow path of the natural gas and gas and thus extending the reaction time.

[0042] Specifically, the structure of the dust removal assembly includes a dust removal pipeline, a first settling chamber 10, and a second settling chamber 11 connected in sequence. The first settling chamber 10 and the second settling chamber 11 are connected by a high-temperature resistant pipeline. The air inlet of the dust removal pipeline is connected to the air outlet of the gasifier 3, and the air outlet of the second settling chamber 11 is connected to the air inlet of the gas reformer. In this way, the gas can undergo secondary dust removal after passing through the first settling chamber and tertiary dust removal after passing through the second settling chamber.

[0043] To enable the dust removal function of the dust removal pipeline, for example, the dust removal pipeline includes a gas riser pipe 7 and a gas downcomer pipe 9 connected sequentially along the gas flow direction. Along the gas flow direction, the gas riser pipe 7 is inclined upwards, and the gas downcomer pipe 9 is inclined downwards, extending to the lower part of the first settling chamber 10. In this way, on the one hand, after the gas flowing out of the gasifier 3 enters the gas riser pipe 7, the larger dust particles in the gas will fall onto the side wall of the gas riser pipe 7 under the action of gravity, and move downwards back into the gasifier 3, and finally fall into the intermediate frequency furnace 1, thereby enabling the gas to be dusted once; on the other hand, the setting of the gas downcomer pipe 9 can facilitate the transportation of gas.

[0044] Specifically, the structure of the second settling chamber 11 is a cyclone separation structure, including a cyclone cone and a guide tube 8. A cyclone inlet is opened on the side of the cyclone cone, and the outlet direction of the cyclone inlet is inclined relative to the radial direction of the cyclone cone. The cyclone inlet is connected to the outlet of the first settling chamber 10. The bottom end of the cyclone cone is closed. The guide tube 8 is located inside the cyclone cone and is coaxially arranged with it. An airflow loop exists between the bottom end of the guide tube 8 and the cyclone cone, and the top end of the guide tube 8 is sealed to the cyclone cone. In this way, the gas enters the cyclone cone from the cyclone inlet and flows downwards along the cyclone cone to its bottom end. Because the bottom end of the cyclone cone is closed, the gas can only flow into the guide tube 8 through the airflow loop, and then move upwards along the guide tube 8 and out of the second settling chamber 11. Dust in the gas will be deposited at the bottom of the cyclone cone.

[0045] Based on the dust removal assembly with the above structure, the first settling chamber 10 and the second settling chamber 11 are arranged in series and connected by a high-temperature resistant pipeline. The gas downcomer 9 extends to the lower part of the first settling chamber 10. As the gas velocity decreases significantly after passing through the gas riser 7 and the gas downcomer 9, the dust particles correspondingly lose their momentum. Some larger dust particles will settle at the bottom of the first settling chamber 10. The airflow flows upward along the space between the gas downcomer 9 and the inner wall of the first settling chamber 10 into the high-temperature resistant pipeline, and then flows from the second settling chamber through the high-temperature resistant pipeline. The gas enters the second settling chamber 11 through the side (i.e., the cyclone inlet). Since the second settling chamber 11 is a cyclone dust removal structure, the gas flows downward along the inner wall of the cyclone cone of the second settling chamber 11 to the bottom of the second settling chamber 11. The dust falls into the bottom of the second settling chamber 11. After the gas swirls to the bottom of the second settling chamber 11, it enters the air guide duct 8 through the airflow loop and flows upward in the opposite direction along the center line of the air guide duct, and further enters the gas reformer. The bottom of both the first settling chamber 10 and the second settling chamber 11 has ash discharge ports to facilitate dust cleaning.

[0046] It should be emphasized here that in the coal gasification unit for direct reduction in a gas-based reduction shaft furnace in this embodiment, before the coal gas is supplied to the gas-based reduction shaft furnace, dust removal and reforming are carried out using tanks (e.g., reforming furnace body 12, first settling chamber 10 and second settling chamber 11) and pipelines (gas riser pipe 7 and gas downcomer pipe 9). Dust removal is achieved by utilizing the gravity and change in the motion state of the dust itself, without the need to cool the coal gas. Effective dust removal can be achieved without cooling, so that the dust-removed and reformed coal gas can be directly used in the gas-based reduction shaft furnace.

[0047] This invention also provides a method for producing low-carbon molten steel, silicon-vanadium alloy, and titanium-rich slag, see [link to relevant documentation]. Figure 1 It includes the following steps:

[0048] Step I: Vanadium-titanium magnetite oxide pellets are directly reduced in a vertical shaft furnace using gas-based reduction to obtain metallized pellets;

[0049] Step II: The metallized pellets are hot-charged into an electric furnace (e.g., an open-arc operation electric furnace) and subjected to a single melting process without the addition of a reducing agent to produce low-carbon molten steel and iron-vanadium-titanium slag. The low-carbon molten steel contains less than 0.1% C by mass, more than 99.0% Fe by mass, and very low levels of elements such as silicon, manganese, P, and S.

[0050] It should be noted that, on the one hand, the metallized pellets themselves do not contain carbon, and no reducing agent is added during electric furnace melting. Since there is no carbon in the melting process, the molten iron will not be carburized, thus producing low-carbon molten iron. On the other hand, during the first melting process, the low-carbon molten iron and the iron-vanadium-titanium slag are mainly separated by density difference.

[0051] Step III: Mix the iron-vanadium-titanium slag with coke and charge it into an electric furnace (e.g., a submerged arc furnace) for secondary melting and reduction. The secondary melting temperature is 1600-1800℃ and the secondary melting time is 60-120 min, generating silicon-vanadium alloy and titanium-rich slag. The mass percentage of V in the silicon-vanadium alloy is >3%, and the mass percentage of TiO2 in the titanium-rich slag is >50%.

[0052] In order to obtain a high metallization rate, in step I above, the gas-solid ratio is 1.2 to 1.6 m. 3 Under the condition of / kg, gas-based reduction is carried out in a vertical shaft furnace for direct gas-based reduction. In practical applications, the metallization rate of the obtained metallized pellets is 85% to 90%, thus effectively ensuring the iron recovery rate.

[0053] To reduce the energy consumption of the electric furnace, the charging temperature of the metallized pellets in step II above is 700–900°C. This is because if the charging temperature is too low, the energy consumption of the electric furnace melting process will be high; if the charging temperature is too high, the conveying equipment will be unable to withstand the high temperature.

[0054] To ensure sufficient melting, in step II above, the melting temperature is 1550–1650℃ and the melting time is 30–90 minutes. This is because if the melting temperature is too low and the melting time is too short, sufficient melting cannot be achieved, reducing melting efficiency; if the melting temperature is too high and the melting time is too long, it will not only lead to high power consumption but also shorten the service life of the electric furnace.

[0055] To improve the alloy recovery rate, in step III above, the amount of coke added is 15-25% of the mass of the iron-vanadium-titanium slag. This ensures a sufficient amount of coke, thereby promoting alloy reduction and improving the alloy recovery rate.

[0056] The present invention will be further described below with reference to embodiments.

[0057] Example 1

[0058] The composition of the vanadium-titanium magnetite oxide pellets in this embodiment, by mass percentage, includes: TFe 54.50%, FeO 14.84%, V2O 51.62%, and TiO 213.23%.

[0059] The production method in this embodiment is as follows:

[0060] Vanadium-titanium magnetite oxide pellets were charged into a gas-based reduction shaft furnace for reduction. The reducing gas composition was 61.5% CO and 30.8% H2, with a gas-to-solid ratio of 1.2 m³ / s. 3 / kg, the reducing gas heating temperature is 950℃, the reduction time is 240min, and the metallization rate of the metallized pellets obtained by reduction is 88.5%. The metallized pellets are hot-charged into the electric furnace at a charging temperature of 750℃. The primary melting temperature of the electric furnace is 1550℃, and the melting time is 90min. The molten steel obtained by melting has an Fe content of 99.1% and a C content of 0.08%. The low-carbon molten steel is used to produce silicon steel. The iron-vanadium-titanium slag obtained by melting has an FeO content of 31.2%, a V2O5 content of 5.2%, and a TiO2 content of 36.9%. The iron-vanadium-titanium slag obtained by primary melting is mixed with 20% coke by mass and subjected to secondary melting in the electric furnace at a melting temperature of 1750℃ and a melting time of 90min. The melting yields silicon-vanadium alloy and titanium-rich slag. The silicon-vanadium alloy has a V content of 9.8% and a Si content of 6.4%, and the titanium-rich slag has a TiO2 content of 56.8%.

[0061] Example 2

[0062] The composition of the vanadium-titanium magnetite oxide pellets in this embodiment, by mass percentage, includes: TFe 57.2%, FeO 32.56%, V2O 50.65%, and TiO 212.10%.

[0063] The production method in this embodiment is as follows:

[0064] Vanadium-titanium magnetite oxide pellets were charged into a gas-based reduction shaft furnace for reduction. The reducing gas composition was 60% CO and 30% H2, with a gas-to-solid ratio of 1.6 m³ / s. 3 / kg, the reducing gas heating temperature is 900℃, the reduction time is 300min, and the metallization rate of the metallized pellets obtained by reduction is 86.0%. The metallized pellets are hot-charged into the electric furnace at a charging temperature of 900℃. The primary melting temperature of the electric furnace is 1600℃, and the melting time is 60min. The molten steel obtained by melting has an Fe content of 99.3% and a C content of 0.06%. The low-carbon molten steel is used to produce industrial pure iron. The iron-vanadium-titanium slag obtained by melting has an FeO content of 34.5%, a V2O5 content of 2.1%, and a TiO2 content of 38.3%. The iron-vanadium-titanium slag obtained by primary melting is mixed with 25% coke by mass and subjected to secondary melting in the electric furnace at a melting temperature of 1800℃ and a melting time of 30min. The melting yields silicon-vanadium alloy and titanium-rich slag. The silicon-vanadium alloy has a V content of 3.6% and a Si content of 5.6%, and the titanium-rich slag has a TiO2 content of 60.2%.

[0065] Example 3

[0066] The composition of the vanadium-titanium magnetite oxide pellets in this embodiment, by mass percentage, includes: TFe 48.0%, FeO 20.3%, V2O 51.70%, and TiO 20.6%.

[0067] The production method in this embodiment is as follows:

[0068] Vanadium-titanium magnetite oxide pellets were charged into a gas-based reduction shaft furnace for reduction. The reducing gas composition was 62% CO and 33% H2, with a gas-to-solid ratio of 1.3 m³ / s. 3 / kg, the reducing gas heating temperature is 950℃, the reduction time is 180min, and the metallization rate of the metallized pellets obtained by reduction is 85%. The metallized pellets are hot-charged into the electric furnace at a charging temperature of 800℃. The primary melting temperature of the electric furnace is 1650℃, and the melting time is 90min. The molten steel obtained by melting has an Fe content of 99.0% and a C content of 0.09%. The low-carbon molten steel is used to produce silicon steel. The iron-vanadium-titanium slag obtained by melting has an FeO content of 25.6%, a V2O5 content of 6.3%, and a TiO2 content of 43.5%. The iron-vanadium-titanium slag obtained by primary melting is mixed with 15% coke by mass and subjected to secondary melting in the electric furnace at a melting temperature of 1800℃ and a melting time of 60min. The melting yields silicon-vanadium alloy and titanium-rich slag. The silicon-vanadium alloy has a V content of 12.3% and a Si content of 4.5%, and the titanium-rich slag has a TiO2 content of 66.5%.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for producing low carbon steel, silicon vanadium alloy and titanium-rich slag, characterized in that, The production system comprises an oxidized pellet supply unit, a gas-based reduction shaft furnace, a primary smelting electric furnace and a secondary smelting electric furnace; the oxidized pellet is a vanadium-titanium magnetite oxidized pellet; the gas-based reduction shaft furnace is provided with a reduction gas inlet; the secondary smelting electric furnace is provided with a coke inlet; the oxidized pellet outlet of the oxidized pellet supply unit is connected with the oxidized pellet inlet of the gas-based reduction shaft furnace; the metallized pellet outlet of the gas-based reduction shaft furnace is connected with the metallized pellet inlet of the primary smelting electric furnace; the slag outlet of the primary smelting electric furnace is connected with the slag inlet of the secondary smelting electric furnace; the gas-based reduction shaft furnace is used for converting the vanadium-titanium magnetite oxidized pellet and the reduction gas into metallized pellet; the primary smelting electric furnace is used for converting the metallized pellet into low-carbon molten steel and iron vanadium titanium slag without adding a reducing agent; and the secondary smelting electric furnace is used for converting the iron vanadium titanium slag and the coke into silicon vanadium alloy and titanium-rich slag. The reduction gas inlet comprises a plurality of CO inlets and a plurality of H2 inlets; the production system further comprises a coal gasification unit for preparing CO, the coal gasification unit comprising a post-treatment unit and a medium-frequency furnace and a gasifier connected in sequence, the gasifier being arranged above the medium-frequency furnace; the post-treatment unit comprises a dust removal assembly; the dust removal assembly comprises a dust removal pipeline, a first sedimentation chamber and a second sedimentation chamber connected in sequence, and the gas outlet of the gasifier is connected with the gas inlet of the dust removal pipeline. The dust removal pipeline comprises a coal gas upward pipe and a coal gas downward pipe connected in sequence along the coal gas flow direction; along the coal gas flow direction, the coal gas upward pipe is inclined upward, and the coal gas downward pipe is inclined downward; the coal gas downward pipe extends to the lower part of the first sedimentation chamber. The second sedimentation chamber comprises a cyclone cone and a wind guide cylinder; a cyclone inlet is arranged on the side surface of the cyclone cone; the gas outlet direction of the cyclone inlet is arranged in an inclined manner relative to the radial direction of the cyclone cone; the cyclone inlet is connected with the gas outlet of the first sedimentation chamber; the bottom end of the cyclone cone is closed; the wind guide cylinder is arranged in the cyclone cone; the bottom end of the wind guide cylinder and the cyclone cone have an airflow annular channel; and the top end of the wind guide cylinder is sealingly connected with the cyclone cone.

2. The production system for low-carbon molten steel, silicon vanadium alloy and titanium-rich slag according to claim 1, wherein the gas-based reduction shaft furnace is connected with the primary smelting electric furnace through a heat preservation conveying assembly.

3. The production system for low-carbon molten steel, silicon vanadium alloy and titanium-rich slag according to claim 1, wherein the gas-based reduction shaft furnace is directly connected with the primary smelting electric furnace.

4. The production system for low-carbon molten steel, silicon vanadium alloy and titanium-rich slag according to claim 1, wherein the plurality of CO inlets are uniformly arranged along the circumference of the gas-based reduction shaft furnace, and the plurality of H2 inlets are uniformly arranged along the circumference of the gas-based reduction shaft furnace.

5. The production system for low-carbon molten steel, silicon vanadium alloy and titanium-rich slag according to claim 4, wherein the flow rate ratio of the CO inlets to the H2 inlets is 11-14:6-9.

6. The production system for low-carbon molten steel, silicon vanadium alloy and titanium-rich slag according to any one of claims 1 to 5, wherein the mass percentage of C in the low-carbon molten steel is <0.1%, and the mass percentage of Fe is >99.0%.

7. The production system of low carbon steel, silicon-vanadium alloy and titanium-rich slag according to any one of claims 1 to 5, wherein the mass percentage of V in the silicon-vanadium alloy is > 3%, and the mass percentage of TiO2 in the titanium-rich slag is > 50%.

8. The production system of low carbon steel, silicon-vanadium alloy and titanium-rich slag according to any one of claims 1 to 5, wherein the metallization rate of the metallized pellets is 85% to 90%.

9. A method for producing low carbon steel, silicon vanadium alloy and titanium-rich slag, characterized in that, The production system according to any one of claims 1 to 8 is used to produce low carbon steel, silicon-vanadium alloy and titanium-rich slag.

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