Method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas

Abstract

The invention relates to the field of chemical engineering and steel smelting, and discloses a method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas, which comprises the following steps: S1, measuring the temperature of overline-crossing molten iron, sampling, and testing and analyzing the components of the molten iron; s2, measuring the temperature of the molten iron mixed into the converter; s3, according to the temperature measurement result in the S1 and the temperature measurement result in the S2, the charging temperature is corrected; s4, according to the corrected charging temperature, the proportion of the mixed gas is adjusted in a staged mode for blowing; s5, adding a coolant and pig iron into the furnace according to an analysis result in S1; and S6, after blowing is completed, slag and steel are separated, and vanadium slag and low-residue vanadium semisteel are obtained. According to the scheme, in order to solve the problems that in an existing vanadium extraction process, the temperature of a molten pool rises too fast, the stirring effect is insufficient, and the vanadium oxidation rate is limited, the recovery rate of vanadium is increased and the content of residual vanadium in semi-steel is reduced by accurately controlling the nitrogen-oxygen mixed blowing proportion, reasonably distributing the blowing time and combining heat balance calculation and end point control; and meanwhile, molten steel quality and subsequent steelmaking process requirements are guaranteed.

Description

Technical Field

[0001] The present invention relates to the fields of chemical engineering and iron and steel smelting, and particularly to a method for extracting vanadium by top-blowing a nitrogen-oxygen mixed gas. Background Art

[0002] Vanadium, as an important strategic resource, has extensive applications in multiple fields such as iron and steel smelting, chemical engineering, aerospace, etc. One of the main sources of vanadium is vanadium-titanium magnetite, which often contains associated elements such as Ti and Fe. In China, currently the mainstream vanadium extraction process mainly relies on blast furnace ironmaking to obtain vanadium-containing hot metal from vanadium-titanium magnetite, and then through the method of blowing oxygen in an oxygen converter, the vanadium in the hot metal is selectively oxidized to form V2O5 and enter the slag, realizing the separation of slag and steel, and finally obtaining crude vanadium slag. Subsequently, the crude vanadium slag undergoes processes such as crushing and magnetic separation to be prepared into fine vanadium slag suitable for wet vanadium extraction. During the vanadium extraction process in the oxygen converter, based on the principle of selective oxidation, the oxidation sequence of carbon and vanadium is affected by temperature. When the molten bath temperature reaches about 1357 °C, the oxidation of vanadium takes precedence over carbon, and when the temperature exceeds this threshold, carbon is preferentially oxidized. Therefore, in order to improve the recovery rate of vanadium, it is necessary to reasonably control the molten bath temperature during the converter operation to make it rise slowly so that more vanadium is oxidized and enters the slag. In addition, after meeting the thermodynamic conditions for carbon-vanadium conversion, it is also necessary to optimize the kinetic conditions. By adjusting the top-blowing oxygen flow rate, enhancing the stirring intensity of the molten bath, increasing the mass transfer rate of vanadium in the hot metal, and expanding the reaction zone area, the full oxidation of vanadium can be promoted. However, the traditional oxygen converter vanadium extraction process has certain limitations. Relying solely on top-blowing oxygen may cause the molten bath temperature to rise too fast, affecting the selective oxidation of vanadium, and at the same time increasing the risk of over-oxidation of the molten steel, thereby affecting the final recovery rate of vanadium.

[0003] Therefore, there is still room for improvement in the existing technology. Summary of the Invention

[0004] In view of this, the purpose of the embodiments of the present invention is to propose a method for extracting vanadium by top-blowing a nitrogen-oxygen mixed gas. This method addresses the problems in the existing vanadium extraction process such as too fast rise of the molten bath temperature, insufficient stirring effect, and limited vanadium oxidation rate, and proposes a more optimized operation plan. By precisely controlling the nitrogen-oxygen mixed blowing ratio, reasonably allocating the blowing time, and combining heat balance calculation and endpoint control, the recovery rate of vanadium is increased, the residual vanadium content in semi-steel is reduced, while ensuring the quality of molten steel and the requirements of subsequent steelmaking processes.

[0005] Based on the above purpose, the embodiments of the present invention provide a method for extracting vanadium by top-blowing a nitrogen-oxygen mixed gas, including: S1, measuring the temperature of the hot metal on the transfer line and sampling and analyzing the composition of the hot metal; S2, measuring the temperature of the hot metal charged into the converter; S3, correcting the furnace charging temperature according to the temperature measurement results in S1 and the temperature measurement results in S2; S4. Adjust the proportion of the mixed gas in stages for blowing according to the corrected tapping temperature. S5. Add coolants and pig iron blocks to the furnace according to the analysis results in S1. S6. After the blowing is completed, separate the slag and steel to obtain vanadium slag and semi-steel with low residual vanadium.

[0006] According to an embodiment of the present invention, in step S1, the molten iron composition analysis includes the detection of the contents of carbon and vanadium elements.

[0007] According to an embodiment of the present invention, step S2 includes: using an infrared thermometer to measure the temperature of the molten iron in real time during the process of charging molten iron into the converter.

[0008] According to an embodiment of the present invention, step S3 includes: comparing the temperature measurement results in S1 and the temperature measurement results in S2, and correcting the tapping temperature with the lower value thereof. According to an embodiment of the present invention, in step S4, the mixed gas includes oxygen and nitrogen.

[0009] According to an embodiment of the present invention, in step S4, the proportion of nitrogen in the mixed gas is 20% - 40%.

[0010] According to an embodiment of the present invention, step S4 includes: blowing the mixed gas into the furnace by top-blowing nitrogen through an oxygen lance, and adjusting the proportion of nitrogen according to the tapping temperature for blowing.

[0011] According to an embodiment of the present invention, in step S4, the blowing stage includes the early blowing stage, the middle blowing stage, and the late blowing stage.

[0012] According to an embodiment of the present invention, step S5 includes: determining the carbon content of the molten iron according to the analysis results, performing a heat balance calculation based on the carbon content and the temperature of the molten iron to obtain the addition amount of the coolant, the addition amount of the pig iron block, and the blowing time.

[0013] According to an embodiment of the present invention, in step S5, the blowing time is 4 - 8 minutes.

[0014] The present invention has at least the following beneficial technical effects: The present invention provides a method for vanadium extraction by top-blowing a nitrogen-oxygen mixed gas. A method of blowing a mixture of nitrogen and oxygen into hot metal is adopted on a 200t large-scale vanadium extraction converter. By precisely controlling the ratio of nitrogen-oxygen mixed blowing, optimizing the blowing time, and reasonably distributing the addition amount of coolant, while slowing down the rising rate of the molten bath temperature, good stirring kinetic conditions are ensured, enabling as much vanadium in the hot metal as possible to be oxidized and enter the slag. On the premise of ensuring good stirring of the molten bath, the rising rate of the molten bath temperature is effectively reduced. At the same time, by blowing an inert gas, the risk of over-oxidation of the molten steel is reduced, thereby promoting the further oxidation of vanadium into the slag, increasing the recovery rate of vanadium, reducing the residual vanadium in semi-steel, and reducing the blowing loss of carbon. This improvement not only optimizes the converter vanadium extraction process but also further enhances the economy and controllability of the vanadium extraction process. Each step is closely linked, not only increasing the recovery rate of vanadium but also reducing the residual vanadium in semi-steel, while ensuring the quality of the molten steel and the requirements of the subsequent steelmaking process, with significant economic benefits and process optimization effects. Detailed implementation manners

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the embodiments of the present invention in conjunction with specific embodiments.

[0016] The terms "including" and "having" in the description and claims of the present invention, as well as any variations thereof, are intended to cover non-exclusive inclusion; the terms "first", "second", etc. in the description and claims of the present invention are used to distinguish different objects, rather than to describe a specific order. The meaning of "a plurality" is two or more, unless otherwise specifically and clearly defined.

[0017] In addition, the mention of "embodiment" in this article means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0018] The method for vanadium extraction by top-blowing a nitrogen-oxygen mixed gas provided by the present invention includes the following steps: S1. Measure the temperature of the hot metal on the transfer line and take samples for chemical analysis of the hot metal composition; S2. Measure the temperature of the hot metal charged into the converter; S3. Correct the tapping temperature according to the temperature measurement results in S1 and the temperature measurement results in S2; S4. Adjust the ratio of the mixed gas in stages for blowing according to the corrected tapping temperature; S5. Add coolant and pig iron blocks to the furnace according to the analysis results in S1; S6. After the blowing is completed, the slag and steel are separated to obtain vanadium slag and semi-steel with low residual vanadium.

[0019] According to an embodiment of the present invention, in step S1, during the transfer of hot metal through the transfer line, the temperature of the hot metal is measured in real time by automatic temperature measurement, and samples are taken for chemical analysis of the composition to obtain the initial composition and temperature data of the hot metal. This ensures that the subsequent blowing parameters are adjusted based on the accurate composition of the hot metal, improving the process stability.

[0020] According to an embodiment of the present invention, in step S2, during the process of charging hot metal into the vanadium extraction converter, an infrared temperature measurement device is used to monitor the temperature of the charged hot metal in real time to obtain accurate hot metal temperature data. Infrared temperature measurement can provide fast and non-contact temperature measurement, ensuring the accuracy of the temperature data during the hot metal charging process. Combining with the temperature measurement data on the transfer line in step S1 can effectively avoid the errors of a single temperature measurement method, improve the reliability of the furnace inlet temperature, and provide a basis for determining the subsequent blowing parameters.

[0021] According to an embodiment of the present invention, in step S3, combining the temperature measurement data on the transfer line in step S1 and the infrared temperature measurement data of the charged hot metal in step S2, a low-value correction strategy is adopted, that is, the lower value of the two measurements is taken as the furnace inlet temperature. This can avoid the out-of-control oxidation rate caused by local overheating, ensure the stable increase of the molten pool temperature during the blowing process, and is conducive to optimizing the ratio of nitrogen and oxygen in the mixed gas according to the corrected furnace inlet temperature later, improving the selectivity of vanadium oxidation into the slag, and increasing the vanadium recovery rate.

[0022] According to an embodiment of the present invention, in step S4, according to the corrected furnace inlet temperature, a suitable nitrogen-oxygen mixed blowing ratio is selected in stages. For example, in the early stage of blowing, the temperature rise rate of the hot metal is controlled by adjusting the nitrogen proportion in the mixed gas to avoid local overheating of the molten pool. In the middle stage of blowing, the stirring intensity of the molten pool is enhanced by adjusting the nitrogen proportion in the mixed gas to improve the mass transfer rate of vanadium in the hot metal and promote the oxidation of vanadium into the slag. In the late stage of blowing, the nitrogen proportion in the mixed gas is adjusted to balance the vanadium oxidation and the quality of the molten steel, enabling the oxidation reaction to proceed fully, optimizing the endpoint control, and increasing the vanadium recovery rate. By dynamically adjusting the nitrogen-oxygen ratio in the mixed gas, the flexibility and control accuracy of the blowing process are improved, ensuring the selective oxidation of vanadium and increasing the content of vanadium pentoxide in the vanadium slag.

[0023] According to an embodiment of the present invention, in step S5, based on the initial carbon content and temperature of the hot metal obtained from the component analysis, the addition amounts of the coolant and the pig iron are calculated to ensure that the temperature of the molten bath in the furnace is maintained within a reasonable range. Calculate the blowing time of this heat to ensure the full oxidation of vanadium in the hot metal, while avoiding over-oxidation that affects the quality of the semi-steel. Accurately calculate the coolant consumption through the carbon temperature of the incoming material to avoid insufficient vanadium oxidation or a decrease in the quality of the semi-steel caused by overheating. Calculate a reasonable blowing time, which can not only ensure the full oxidation of vanadium but also reduce carbon blowing loss and improve the overall vanadium extraction efficiency.

[0024] According to an embodiment of the present invention, in step S6, based on the calculated blowing time, the addition amounts of the coolant and the pig iron, and the nitrogen-oxygen mixed blowing ratio, operations are carried out and the endpoint control is optimized. Control the carbon content and the semi-steel temperature at the endpoint to meet the requirements of the subsequent steelmaking process. By adjusting the blowing time and the nitrogen-oxygen ratio, control the vanadium pentoxide content in the vanadium extraction slag. Accurately control the carbon content at the endpoint to stabilize the semi-steel composition and improve the steelmaking quality. By dynamically adjusting the endpoint parameters, improve the recovery rate of vanadium, reduce the residual vanadium loss, ensure the quality stability of the product after vanadium extraction, and improve the economic efficiency and process reliability.

[0025] The present invention provides a method for extracting vanadium by top-blowing a nitrogen-oxygen mixed gas. On a 200t large-scale vanadium extraction converter, a method of blowing a mixture of nitrogen and oxygen into the hot metal is adopted. By accurately controlling the nitrogen-oxygen mixed blowing ratio, optimizing the blowing time, and reasonably distributing the addition amount of the coolant, while slowing down the rising rate of the molten bath temperature, good stirring conditions are ensured, and as much vanadium as possible in the hot metal is oxidized and enters the slag. On the premise of ensuring good stirring of the molten bath, effectively reduce the rising rate of the molten bath temperature. At the same time, blow in an inert gas to reduce the risk of over-oxidation of the molten steel, thereby promoting the further oxidation of vanadium into the slag, improving the recovery rate of vanadium, reducing the residual vanadium in the semi-steel, and reducing the carbon blowing loss. This improvement not only optimizes the vanadium extraction process of the converter but also further improves the economy and controllability of the vanadium extraction process. Each step is closely linked, which not only improves the recovery rate of vanadium but also reduces the residual vanadium in the semi-steel. At the same time, it ensures the quality of the molten steel and the requirements of the subsequent steelmaking process, with significant economic benefits and process optimization effects.

[0026] According to an embodiment of the present invention, in step S1, the hot metal component analysis includes the detection of the contents of carbon and vanadium elements.

[0027] According to an embodiment of the present invention, step S2 includes: using an infrared thermometer to measure the temperature of the hot metal in real time during the process of charging the converter with hot metal.

[0028] According to an embodiment of the present invention, step S3 includes: comparing the temperature measurement results in S1 and S2, and correcting the incoming furnace temperature with the lower value among them. According to an embodiment of the present invention, in step S4, the mixed gas includes oxygen and nitrogen.

[0029] According to an embodiment of the present invention, in step S4, the proportion of nitrogen in the mixed gas is 20% - 40%.

[0030] According to an embodiment of the present invention, step S4 includes: blowing the mixed gas into the furnace by top - blowing nitrogen through an oxygen lance, and adjusting the proportion of nitrogen according to the temperature of the molten iron entering the furnace for smelting.

[0031] According to an embodiment of the present invention, in step S4, the smelting stage includes the early stage of smelting, the middle stage of smelting, and the late stage of smelting.

[0032] According to an embodiment of the present invention, step S5 includes: determining the carbon content of the hot metal according to the analysis result, performing a heat balance calculation based on the carbon content and the temperature of the hot metal to obtain the addition amount of the coolant, the addition amount of the pig iron, and the smelting time.

[0033] According to an embodiment of the present invention, in step S5, the smelting time is 4 - 8 min.

[0034] According to an embodiment of the present invention, the advantages of the above - mentioned operation steps include: adopting the method of blowing nitrogen and oxygen into the hot metal on a 200t large - scale vanadium - extracting converter. By precisely controlling the ratio of nitrogen - oxygen mixed blowing, optimizing the smelting time, and reasonably distributing the addition amount of the coolant, while slowing down the rising rate of the molten bath temperature, good stirring kinetic conditions are ensured, enabling as much vanadium in the hot metal as possible to be oxidized and enter the slag. On the premise of ensuring good stirring of the molten bath, the rising rate of the molten bath temperature is effectively reduced. At the same time, by blowing inert gas, the risk of over - oxidation of the molten steel is reduced, thereby promoting the further oxidation of vanadium into the slag, increasing the recovery rate of vanadium, reducing the residual vanadium in the semi - steel, and reducing the blowing loss of carbon. This improvement not only optimizes the vanadium - extracting process of the converter but also further enhances the economy and controllability of the vanadium - extracting process. Each step is closely linked, not only increasing the recovery rate of vanadium but also reducing the residual vanadium in the semi - steel, while ensuring the quality of the molten steel and the requirements of the subsequent steel - making process, with significant economic benefits and process optimization effects.

[0035] The following further explains the present invention with specific embodiments and comparative examples.

[0036] Example 1 a. Temperature measurement and sampling: The hot metal is automatically temperature - measured and sampled across the transfer line. The temperature of the hot metal across the line is measured to be 1394 °C. After chemical analysis, the carbon content in the hot metal composition is 4.26% and the vanadium content is 0.354%.

[0037] b. Infrared temperature measurement during hot metal charging: During the process of charging hot metal into the vanadium - extracting converter, the temperature of the charged hot metal is measured in real - time by infrared temperature measurement, and the infrared temperature measurement result is 1315 °C.

[0038] c. Revised tapping temperature: Considering the molten iron temperature across the transfer line and the infrared temperature measurement result of the hot metal being poured, the lower value of 1315 °C is used to revise the tapping temperature.

[0039] d. Nitrogen-oxygen mixed blowing: According to the tapping temperature, adjust the nitrogen proportion in the mixed gas during the early stage of blowing to 20%, during the middle stage to 30%, and during the late stage to 40%.

[0040] e. Heat balance calculation: Based on the carbon content and the temperature of the hot metal, the coolant addition amount is calculated to be 15840 kg, the pig iron addition amount is 15 t, and the blowing time is 7 min.

[0041] f. Endpoint control: Based on the calculated blowing time, coolant addition amount, and the nitrogen proportion in the mixed gas at each stage, perform the blowing operation to control the carbon content at the end of blowing to 3.52% and the semi-steel tapping temperature to 1348 °C, meeting the smelting requirements of the next process. The vanadium recovery rate can be increased to 85%, and the residual vanadium in the semi-steel is reduced to 0.022%.

[0042] Comparative Example 1 Directly blow the hot metal with pure oxygen. The blowing time is 5.5 min. After blowing, the vanadium recovery rate is 78.4%, and the residual vanadium in the semi-steel is 0.036%.

[0043] In Example 1, based on operations such as revised tapping temperature, nitrogen-oxygen mixed blowing, heat balance calculation, and endpoint control, the temperature rise rate during the blowing process is reduced compared to traditional pure oxygen blowing to optimize the oxidation rate of vanadium and increase the vanadium recovery rate. In Comparative Example 1, during the blowing process, the blowing time and coolant control are inaccurate and pure oxygen blowing is used, resulting in a faster temperature rise rate, insufficient stirring in some stages, and unstable vanadium mass transfer rate, reducing the vanadium recovery rate.

[0044] The present invention provides a method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas. On a 200 t large-scale vanadium extraction converter, a method of blowing a mixture of nitrogen and oxygen into the hot metal is adopted. By precisely controlling the nitrogen-oxygen mixed blowing ratio, optimizing the blowing time, and reasonably distributing the coolant addition amount, while slowing down the molten pool temperature rise rate, good stirring conditions are ensured, enabling as much vanadium in the hot metal as possible to be oxidized into the slag. On the premise of ensuring good stirring of the molten pool, the molten pool heating rate is effectively reduced. At the same time, by blowing inert gas, the risk of steel water over-oxidation is reduced, thereby promoting the further oxidation of vanadium into the slag, increasing the vanadium recovery rate, reducing the residual vanadium in the semi-steel, and reducing the carbon blow loss. This improvement not only optimizes the converter vanadium extraction process but also further enhances the economy and controllability of the vanadium extraction process. Each step is closely linked, not only increasing the vanadium recovery rate but also reducing the residual vanadium in the semi-steel, while ensuring the quality of the steel water and the requirements of the subsequent steelmaking process, with significant economic benefits and process optimization effects.

[0045] The foregoing are exemplary embodiments disclosed by the present invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments disclosed by the present invention as defined by the claims. The functions, steps, and / or actions of the method claims according to the disclosed embodiments herein need not be performed in any particular order. In addition, although the elements disclosed by the embodiments of the present invention may be described or claimed in individual form, they can also be understood as plural unless explicitly limited to the singular form.

[0046] It should be understood that, as used herein, unless the context clearly supports an exception, the singular form "a" is also intended to include the plural form. It should also be understood that the "and / or" used herein refers to any and all possible combinations including one or more of the associated listed items.

[0047] The serial numbers of the foregoing disclosed embodiments of the present invention are merely for description and do not represent the superiority or inferiority of the embodiments.

[0048] Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features between the above embodiments or different embodiments can also be combined, and there are many other variations in different aspects of the embodiments of the present invention as above, which are not provided in detail for the sake of brevity. Therefore, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present invention shall be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for extracting vanadium by top-blowing a nitrogen-oxygen mixed gas, characterized in that Including: S1, measuring the temperature of the molten iron passing through the cross-line, sampling and analyzing the composition of the molten iron; S2, measuring the temperature of the molten iron poured into the converter; S3, correcting the temperature of the molten iron entering the furnace according to the temperature measurement results in S1 and the temperature measurement results in S2; S4, adjusting the proportion of the mixed gas in stages for blowing according to the corrected temperature of the molten iron entering the furnace; S5, adding a coolant and pig iron blocks to the furnace according to the analysis results in S1; S6, after the blowing is completed, separating the slag and steel to obtain vanadium slag and semi-steel with low residual vanadium.

2. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 1, characterized in that, In step S1, the analysis of the molten iron composition includes the detection of the contents of carbon and vanadium elements.

3. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 1, characterized in that Step S2 includes: using an infrared thermometer to measure the temperature of the molten iron in real time during the process of pouring molten iron into the converter.

4. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 1, wherein Step S3 includes: comparing the temperature measurement results in S1 and the temperature measurement results in S2, and correcting the temperature of the molten iron entering the furnace with the lower value.

5. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 1, characterized in that, In step S4, the mixed gas includes oxygen and nitrogen.

6. The method for vanadium extraction by top-blowing nitrogen-oxygen mixed gas according to claim 5, wherein In step S4, the proportion of nitrogen in the mixed gas is 20% - 40%.

7. The method for vanadium extraction by top-blowing nitrogen-oxygen mixed gas according to claim 1, characterized in that, Step S4 includes: blowing the mixed gas into the furnace by top-blowing nitrogen through an oxygen lance, and adjusting the proportion of nitrogen for blowing according to the temperature of the molten iron entering the furnace.

8. The method for vanadium extraction by top-blowing nitrogen-oxygen mixed gas according to claim 1, characterized in that, In step S4, the blowing stage includes the early stage of blowing, the middle stage of blowing, and the late stage of blowing.

9. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 1, wherein, Step S5 includes: determining the carbon content of the molten iron according to the analysis results, performing a heat balance calculation based on the carbon content and the temperature of the molten iron to obtain the addition amount of the coolant, the addition amount of the pig iron blocks, and the blowing time.

10. The method for extracting vanadium by top-blowing nitrogen-oxygen mixed gas according to claim 7, characterized in that, In step S5, the blowing time is 4 - 8 minutes.