A method for extracting vanadium from a converter

Abstract

The present application relates to the technical field of metallurgy, in particular to a converter vanadium extraction method, vanadium-containing molten iron is mixed into a vanadium extraction converter, after shaking the converter, the bottom of the converter is supplied with gas, the bottom blowing element of the bottom gas supply adopts a single ring slit combined with a central cluster tube mode, the single ring slit is sleeved outside the central cluster tube, the central cluster tube sprays iron red powder with CO2 as the carrier gas, the single ring slit passes CO2 and CH4 mixed gas, and the single ring slit adopts pulse control.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method for vanadium extraction in a converter. Background Technology

[0002] Vanadium is an important transition metal element, primarily derived from vanadium-titanium magnetite. Converter vanadium extraction is one of the main industrial routes for indirect vanadium extraction from vanadium-titanium magnetite, and it is widely used in China (e.g., by Panzhihua Iron and Steel Group and Chengde Iron and Steel Group). The principle involves using oxygen blowing in a converter to oxidize vanadium-containing molten iron, achieving selective oxidation of vanadium into the slag phase to form vanadium slag. During the converter blowing process, temperature control and kinetic improvement are crucial for reducing residual vanadium.

[0003] Patent CN201910093569.X provides a method for vanadium extraction using a binary gas-supply converter. Based on the silicon content and temperature of the vanadium-containing molten iron, the gas supply and blowing conditions are determined. Specifically, when the Si content of the vanadium-titanium molten iron is less than 0.15 wt% and the temperature is 1280–1300 °C, after the vanadium-containing molten iron enters the converter, it is blown with gas through an oxygen lance. O2 is blown in during the period from the start of blowing to 60–120 seconds before the end of blowing. During the period from 60 to 120 seconds before the end of the blowing process to the end of the blowing process, a mixture of O2 and N2 gas is blown in, with the N2 consumption ratio being 20% ​​to 40%; the vanadium extraction coolant is added within 2 minutes after the start of the blowing process. When the Si content of vanadium-titanium molten iron is ≥0.15wt% and the temperature is 1280~1300℃, after the vanadium-containing molten iron enters the converter, it is blown by oxygen lance to blow gas. O2 is blown from the start of blowing to 60~120s after the start of blowing. During the period from 60 to 120 seconds after the start of blowing to 60 to 120 seconds before the end of blowing, a mixture of O2 and N2 gas is blown and sprayed, with the N2 consumption ratio being 10% to 30%; during the period from 60 to 120 seconds before the end of blowing to the end of blowing, a mixture of O2 and N2 gas is blown and sprayed, with the N2 consumption ratio being 20% ​​to 40%. The vanadium-containing coolant is added within 2 minutes after the start of the blowing process. When the temperature of the vanadium-titanium molten iron is >1300℃, after the vanadium-containing molten iron enters the converter, it is blown by gas through an oxygen lance. During the period from the start of the blowing process to 60 to 120 seconds before the end of the blowing process, a mixture of O2 and N2 gas is blown, with the N2 consumption ratio being 20% ​​to 30%. From 60-120 seconds before the end of blowing to the end of blowing, a mixture of O2 and N2 gas is blown in, with N2 consumption at 30%-40%; the vanadium extraction coolant is added within 2 minutes of the start of blowing. This solves the problem of high residual vanadium and low V2O5 in vanadium slag under different temperatures and silicon contents of molten iron. Although top blowing of binary gas slows down the temperature rise of the molten pool, the temperature control and stirring effect of bottom blowing N2 is not as good as that of CO2, and there is still room for further reduction in residual vanadium.

[0004] Patent CN202011380715.6 describes a method for asymmetric bottom-blowing CO2 vanadium extraction in a converter. The method involves adding vanadium-containing molten iron to the converter, shaking the furnace, and then starting CO2 blowing from the bottom of the converter while simultaneously using an oxygen lance for top-blowing O2. The oxygen supply intensity of the oxygen lance is 1.5–3.0 Nm. 3 / min·t iron, lance position controlled at 1.7~2.0m, add coolant within 2 minutes of oxygen lance starting to blow, and blow to the end point; The bottom of the converter is laid with permeable bricks in three zones: Zone I, Zone II, and Zone III. The permeable bricks in Zones I and III are symmetrically distributed, while those in Zone II are asymmetrically distributed, with an included angle of 80°–100°. The bottom-blown CO2 flow rate of a single permeable brick in Zone I is controlled at 100–120 Nm³. 3 / min, the bottom-blown CO2 flow rate of a single permeable brick in Zone II is 130-150 Nm³. 3 The CO2 flow rate from the bottom blown onto a single permeable brick in Zone III is 160–180 Nm³ / min. 3 / min. Carbon dioxide recovery for vanadium extraction in the converter was achieved, suppressing molten pool temperature rise and effectively reducing residual vanadium content. Despite improved molten pool kinetics, the presence of top-blown O2 leading to excessively high oxidation temperatures means there is still room for further reduction in residual vanadium. Summary of the Invention

[0005] The purpose of this invention is to provide a converter vanadium extraction method that solves the technical problem that existing technologies cannot further reduce residual vanadium.

[0006] This invention discloses a method for vanadium extraction in a converter. Vanadium-containing molten iron is added to the vanadium extraction converter, and gas is supplied to the bottom of the converter after shaking. The bottom blowing element of the bottom gas supply adopts a combination mode of single-ring slit and central cluster tube. The single-ring slit is sleeved outside the central cluster tube. The central cluster tube uses CO2 as the carrier gas to blow iron oxide powder. The single-ring slit is circulated with a mixture of CO2 and CH4 gas. The single-ring slit is controlled by pulse.

[0007] Furthermore, the space between the central bundle tubes is filled with magnesium-carbon refractory material, and both the central bundle tubes and the single circumferential seam are stainless steel tubes.

[0008] Furthermore, the central bundle tube has a diameter of 2-4 mm and a wall thickness of 1-2 mm.

[0009] Furthermore, the pressure of the central bundle tube is 0.8~1.2MPa.

[0010] Furthermore, the flow rate in the central bundle tube is 150–180 Nm³. 3 / min, powder-to-air ratio: 25~35 kg / Nm 3 .

[0011] Furthermore, the iron oxide powder is 200-350 mesh.

[0012] Furthermore, the single-ring seam pressure is 0.7~1MPa, and the single-ring seam width is 1~2.5mm.

[0013] Furthermore, the pulse control specifically refers to a flow rate of 40~60 Nm. 3 / min air supply for 20s, then 100~120Nm 3 Supply air at 20 seconds per minute, and repeat this cycle until the blowing process is complete.

[0014] Furthermore, the volume fraction of CH4 in the CO2 and CH4 mixture is 20-40%.

[0015] Furthermore, it also includes top blowing, which supplies CO2 and O2 at a supply intensity of 2.0–3.0 Nm³. 3 / min·t iron.

[0016] Furthermore, when the molten iron temperature is greater than 1300℃, the volume fraction of top-blown CO2 is controlled at 35~50%; when the molten iron temperature is less than 1250℃, the volume fraction of top-blown CO2 is controlled at 10~20%; and when the temperature is between the two, the volume fraction of top-blown CO2 is controlled at 20~35%.

[0017] Furthermore, the position of the top-blown oxygen lance is controlled at 1.7-2.0m, and 15-22 kg / t of coolant is added within 2 minutes of the oxygen lance starting to blow, until the final temperature is below 1390℃.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Using CO2 as the carrier gas to inject iron oxide powder helps slow down the heating of the molten pool, accelerating the oxidation of vanadium in the early stages. Top blowing with O2-CO2 reduces the rate of oxidation and creates favorable thermodynamic conditions for vanadium oxidation. Pulsed bottom blowing enhances stirring and significantly improves vanadium extraction kinetics. The overall effect is lower residual vanadium and better quality semi-steel.

[0019] 2. This invention makes full use of bottom blowing elements and gas supply methods, enhances molten pool dynamics and temperature control, and compared with traditional combined blowing converter for vanadium extraction, the vanadium oxidation rate is increased by more than 2%, and the economic benefit generated per ton of vanadium-containing molten iron is greater than RMB 2.0. Attached Figure Description To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the bottom blowing element structure of the present invention.

[0021] In the above figures, the meanings of each mark are as follows: 1-single circumferential seam, 2-central cluster, 3-stainless steel pipe, 4-magnesium carbon refractory material. Detailed Implementation

[0022] 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 will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0023] The bottom blowing element used in the following embodiments is as follows: Figure 1 As shown, a combination of a single annular seam 1 and a central bundled tube 2 is adopted. The single annular seam 1 is sleeved outside the central bundled tube 2, and the space between the central bundled tubes is filled with magnesia-carbon refractory material 4. Both the central bundled tube and the single annular seam are stainless steel tubes 3. Example 1 This embodiment discloses a converter vanadium extraction method, including the following steps: The vanadium-containing molten iron is added to the vanadium extraction converter, and gas is supplied to the bottom of the converter after shaking. The bottom blowing element adopts a combination of a single annular slot and a central bundled tube. The central bundled tube has a diameter of 2mm and a wall thickness of 1mm. CO2 is used as the carrier gas to blow 200-mesh iron oxide powder at a pressure of 0.8MPa and a flow rate of 150Nm³. 3 / min, Powder-to-air ratio: 25 kg / Nm 3 .

[0024] A single annular slit with a width of 1 mm is used to purge CO2 and CH4 at a pressure of 0.7 MPa. The volume fraction of CH4 is 20%, and the flow rate is 40 Nm³. 3 / min air supply for 20s, then 100Nm 3 Supply air at 20 seconds per minute, and repeat this cycle until the blowing process is complete.

[0025] The top-blown oxygen lance supplies CO2+O2, with a supply intensity of 2.0–3.0 Nm³. 3 / min·t iron, when the molten iron temperature is greater than 1300℃, the CO2 volume fraction is controlled at 35%; when the molten iron temperature is less than 1250℃, the CO2 volume fraction is controlled at 10%; when the temperature is between the two, the CO2 volume fraction is controlled at 30%; the lance position is controlled at 1.7~2.0m; 15kg / t iron coolant is added within 2 minutes of the oxygen lance starting to blow; the blowing is carried out until the final temperature is below 1390℃.

[0026] By making full use of bottom powder injection and gas supply methods, the dynamics and temperature control of the molten pool are enhanced, and the vanadium oxidation rate is 90%, which is 2% higher than that of traditional combined blowing converter for vanadium extraction. The economic benefit of 2 yuan per ton of vanadium-containing molten iron is generated.

[0027] Example 2 The vanadium-containing molten iron is added to the vanadium extraction converter, and gas is supplied to the bottom of the converter after shaking. The bottom blowing element adopts a combination of a single annular slot and a central bundled tube. The central bundled tube has a diameter of 3mm and a wall thickness of 1.5mm. CO2 is used as the carrier gas to blow 270-mesh iron oxide powder at a pressure of 1.0MPa and a flow rate of 165Nm³. 3 / min, Powder-to-air ratio: 30 kg / Nm 3 .

[0028] The single annular slit width is 1.7 mm, CO2 + CH4 is introduced, the pressure is 0.85 MPa, the volume fraction of CH4 is 30%, and the flow rate is 50 Nm³. 3 / min air supply for 20s, then 110Nm 3 Supply air at 20 seconds per minute, and repeat this cycle until the blowing process is complete.

[0029] The top-blown oxygen lance supplies CO2+O2, with a supply intensity of 2.0–3.0 Nm³. 3 / min·t iron, when the molten iron temperature is greater than 1300℃, the CO2 volume fraction is controlled at 42%; when the molten iron temperature is less than 1250℃, the CO2 volume fraction is controlled at 15%; when the temperature is between the two, the CO2 volume fraction is controlled at 30%; the lance position is controlled at 1.7~2.0m; 18kg / t iron coolant is added within 2 minutes of the oxygen lance starting to blow; the blowing is carried out until the final temperature is below 1390℃.

[0030] By making full use of bottom powder injection and gas supply methods, the dynamics and temperature control of the molten pool are enhanced, and the vanadium oxidation rate is 90.5%, which is 2.5% higher than that of traditional combined blowing converter for vanadium extraction. The economic benefit generated per ton of vanadium-containing molten iron is 2.5 yuan.

[0031] Example 3 The vanadium-containing molten iron is added to the vanadium extraction converter, and gas is supplied to the bottom of the converter after shaking. The bottom blowing element adopts a combination of a single annular slot and a central bundled tube. The central bundled tube has a diameter of 4mm and a wall thickness of 2mm. CO2 is used as the carrier gas to blow 350-mesh iron oxide powder at a pressure of 1.2MPa and a flow rate of 180Nm³. 3 / min, Powder-to-air ratio: 35 kg / Nm 3 .

[0032] The single circumferential slit width is 2.5 mm, CO2 + CH4 is introduced, the pressure is 1 MPa, the volume fraction of CH4 is 40%, and the flow rate is 60 Nm³. 3 / min air supply for 20s, then 120Nm 3Supply air at 20 seconds per minute, and repeat this cycle until the blowing process is complete.

[0033] The top-blown oxygen lance supplies CO2+O2, with a supply intensity of 2.0–3.0 Nm³. 3 / min·t iron, when the molten iron temperature is greater than 1300℃, the CO2 volume fraction is controlled at 50%; when the molten iron temperature is less than 1250℃, the CO2 volume fraction is controlled at 20%; when the temperature is between the two, the CO2 volume fraction is controlled at 40%; the lance position is controlled at 1.7~2.0m; 22kg / t iron of coolant is added within 2 minutes of the oxygen lance starting to blow; the blowing is carried out until the final temperature is below 1390℃.

[0034] By making full use of bottom-blowing elements and gas supply methods, the dynamics and temperature control of the molten pool are enhanced, and the vanadium oxidation rate is 91%, which is 3% higher than that of traditional combined blowing converter for vanadium extraction. The economic benefit of each ton of vanadium-containing molten iron is 3 yuan.

[0035] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A method for vanadium extraction in a converter, characterized in that: The vanadium-containing molten iron is added to the vanadium extraction converter. After the converter is shaken, gas is supplied from the bottom. The bottom blowing element of the bottom gas supply adopts a combination mode of single ring slit and central cluster tube. The single ring slit is sleeved outside the central cluster tube. The central cluster tube uses CO2 as the carrier gas to blow iron oxide powder. The single ring slit is circulated with a mixture of CO2 and CH4 gas. The single ring slit is controlled by pulse.

2. The method for vanadium extraction in a converter according to claim 1, characterized in that: The space between the central bundle tubes is filled with magnesium-carbon refractory material, and both the central bundle tubes and the single circumferential seam are stainless steel tubes.

3. The method for vanadium extraction in a converter according to claim 1, characterized in that: The central bundle tube has a diameter of 2-4 mm and a wall thickness of 1-2 mm. And / or, the pressure of the central bundle tube is 0.8~1.2MPa; And / or, the flow rate in the central bundle tube is 150–180 Nm³. 3 / min, powder-to-air ratio: 25~35 kg / Nm 3 .

4. The method for vanadium extraction in a converter according to claim 1, characterized in that: The iron oxide powder is 200-350 mesh.

5. The method for vanadium extraction in a converter according to claim 1, characterized in that: The pressure of the single ring seam is 0.7~1MPa, and the width of the single ring seam is 1~2.5mm.

6. The method for vanadium extraction in a converter according to claim 1, characterized in that: The pulse control specifically refers to a flow rate of 40~60 Nm. 3 / min air supply for 20s, then 100~120Nm 3 Supply air at 20 seconds per minute, and repeat this cycle until the blowing process is complete.

7. The method for vanadium extraction in a converter according to claim 1, characterized in that: The volume fraction of CH4 in the CO2 and CH4 mixture is 20-40%.

8. The method for vanadium extraction in a converter according to claim 1, characterized in that: It also includes top blowing, which supplies CO2 and O2 at a supply intensity of 2.0–3.0 Nm. 3 / min·t iron.

9. A converter vanadium extraction method according to claim 8, characterized in that: When the molten iron temperature is above 1300℃, the volume fraction of top-blown CO2 should be controlled at 35~50%; when the molten iron temperature is below 1250℃, the volume fraction of top-blown CO2 should be controlled at 10~20%; and when the temperature is between the two, the volume fraction of top-blown CO2 should be controlled at 20~35%.

10. A converter vanadium extraction method according to claim 8, characterized in that: The position of the top-blown oxygen lance is controlled at 1.7-2.0m. Within 2 minutes of starting the oxygen lance, 15-22 kg / t of coolant is added to the lance, and the smelting is carried out until the final temperature is below 1390℃.

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