A method for reducing residual vanadium at the end point of a converter vanadium extraction

Abstract

The application discloses a method for reducing residual vanadium in a converter vanadium extraction endpoint. In the converter vanadium extraction process, a production organization mode of blowing multiple heats and then discharging vanadium slag once is adopted, the multiple heats include non-slagging heats and slagging heats, in the non-slagging heats, vanadium-containing molten iron is mixed into a converter, oxygen lance top blowing gas blowing is adopted, bottom blowing stirring is carried out at the bottom of the converter, based on the target temperature of the blowing endpoint, the first time of adding a vanadium extraction cooling agent is within 3 minutes after the beginning of the blowing stage, the first time of adding the vanadium extraction cooling agent is 30-50 kg / tFe, the second time of adding the vanadium extraction cooling agent is within 0.5 minutes before the end of the blowing, the second time of adding the vanadium extraction cooling agent is 5-10 kg / tFe, and the endpoint temperature is controlled to be 1350-1360 DEG C; in the slagging heats, the cooling agent is added completely within 3 minutes before blowing, and then the converter is discharged and the slag is discharged after oxygen blowing is completed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a method for reducing residual vanadium at the end of converter vanadium extraction. BACKGROUND

[0002] China is a large country of vanadium-titanium magnetite and a large country of vanadium resource utilization. Vanadium-titanium magnetite is smelted by a blast furnace to obtain vanadium-containing molten iron, and the vanadium-containing molten iron is used to prepare vanadium slag. At present, there are many production methods for preparing vanadium slag at home and abroad, mainly including a New Zealand ladle vanadium extraction process, a South African ladle vanadium extraction process, a converter vanadium extraction process in Russia and China, and other vanadium extraction processes such as vanadium extraction from vanadium-containing steel slag and stone coal vanadium extraction process. Among them, the converter vanadium extraction process is the best, and the technical and economic indicators are the best.

[0003] The most core control point of the production process system of the converter vanadium extraction at home and abroad is the control of temperature. The molten iron vanadium extraction is a selective oxidation technology, and the converter gas supply vanadium extraction is an exothermic process. The oxidation of the easily oxidized elements in the molten iron causes the molten pool to rapidly heat up. The oxidation of Si and Mn occurs before the oxidation of V, and the vanadium extraction cannot inhibit the reaction. When the temperature exceeds a certain temperature, the oxidation rate of carbon increases, and the oxidation rate of vanadium decreases. This temperature is called the carbon-vanadium conversion temperature. The carbon-vanadium conversion temperature is generally between 1340-1385℃, which is affected by the composition of the molten iron. Therefore, in order to obtain a high vanadium oxidation rate, a vanadium extraction coolant must be added to reduce the temperature of the molten iron to an appropriate range, the temperature of the molten pool must be controlled to be higher than the carbon-vanadium conversion temperature, and the purpose of vanadium extraction and carbon preservation must be achieved. In the current converter vanadium extraction process, one vanadium slag is extracted from 2-3 smelting furnaces, and the non-slag tapping furnace and the slag tapping furnace are operated according to the same schedule. The flexibility of different furnace times is greatly affected, and the high residual vanadium content at the end of the converter vanadium extraction makes the common problem in the prior art.

[0004] Therefore, there is a need for improvement in the converter vanadium extraction method in the prior art. SUMMARY

[0005] Therefore, the purpose of the embodiments of the present application is to provide a method for reducing residual vanadium at the end of converter vanadium extraction, which can improve the oxidation rate of vanadium and reduce the residual vanadium of semi-steel, and is beneficial to the utilization of vanadium resources and the reduction of subsequent steelmaking production cost.

[0006] In order to achieve the above purpose, the embodiments of the present application provide a method for reducing residual vanadium at the end of converter vanadium extraction, which adopts a production organization mode of smelting multiple furnace times and then extracting one vanadium slag. The multiple furnace times include non-slag tapping furnace times and slag tapping furnace times, and the method is characterized in that,

[0007] In non-slag-discharging furnaces, vanadium-containing molten iron is added to the converter and smelted using top-blowing oxygen lances and bottom-blowing stirring. Based on the target temperature at the end of the smelting process, vanadium-extracting coolant is added for the first time within 3 minutes after the start of the smelting stage, with the first addition amount being 30-50 kg / tFe. Vanadium-extracting coolant is added for the second time within 0.5 minutes before the end of the smelting process, with the second addition amount being 5-10 kg / tFe. The final temperature is controlled at 1350-1360℃.

[0008] In the slag-removing furnace cycle, the vanadium-raising coolant is added within 3 minutes before the blowing process, and steel and slag are removed after the oxygen blowing is finished.

[0009] In some embodiments, the vanadium extraction coolant includes one or more combinations of pig iron blocks, dust collector ash, iron oxide scale, and ore.

[0010] In some embodiments, the intensity of O2 blown from the oxygen lance is 1.5–2.5 Nm. 3 / min·tFe.

[0011] In some embodiments, the gases used during bottom blowing agitation include CO2 and N2.

[0012] In some embodiments, the blowing process is carried out in a low gun position in the early stage, in a high gun position in the middle stage, and in a low gun position in the later stage, with the gun position height being 1.7 to 2.0 m.

[0013] In some embodiments, vanadium-containing molten iron is added to the converter and its temperature is measured and its composition is sampled for analysis.

[0014] The present invention has at least the following beneficial technical effects:

[0015] This invention differentiates the control of non-slag-discharging furnace cycles and slag-discharging furnace cycles. In non-slag-discharging furnace cycles, vanadium extraction coolant is added in stages based on the blowing endpoint temperature. This effectively improves the oxidizability of slag, reduces the endpoint temperature and residual vanadium in semi-steel, and lowers the residual vanadium content at the endpoint of vanadium extraction in converters. This is beneficial for the comprehensive utilization of resources and the reduction of vanadium extraction production costs, saving costs and creating benefits for enterprises. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0017] The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification and claims of this invention are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0018] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0019] This invention proposes a method to reduce residual vanadium at the end point of vanadium extraction in converters. It employs a production organization model of multiple heat cycles followed by one vanadium slag discharge cycle, for example, a model of 2-3 heat cycles followed by one vanadium slag discharge cycle. The multiple heat cycles include both non-slag discharge cycles and slag discharge cycles.

[0020] In non-slag-discharging furnaces, vanadium-containing molten iron is added to the converter and smelted using top-blowing oxygen lances, with bottom-blowing stirring at the furnace bottom. Based on the target temperature at the end of the smelting process, vanadium-extracting coolant is added for the first time within 3 minutes after the start of the smelting stage. The first addition amount is 30-50 kg / tFe, which is about 50%-80% of the total coolant usage. The second addition of vanadium-extracting coolant is added 0.5 minutes before the end of the smelting process. The second addition amount is 5-10 kg / tFe. The final temperature is controlled at 1350-1360℃.

[0021] In the slag-removing furnace cycle, the vanadium-raising coolant is added within 3 minutes before the blowing process, and steel and slag are removed after the oxygen blowing is finished.

[0022] Furthermore, the vanadium extraction coolant includes one or more combinations of pig iron blocks, dust collector ash, iron oxide scale, and ore. Among these, the dust collector ash from the vanadium extraction converter needs to be pelletized with a binder to obtain blocky material.

[0023] Furthermore, the intensity of O2 blown from the oxygen lance is 1.5–2.5 Nm. 3 / min·tFe, the gases used during bottom blowing stirring include CO2 and N2.

[0024] Furthermore, the blowing process involves low-position blowing in the early stage, high-position blowing in the middle stage, and low-position blowing in the later stage, with the gun position height ranging from 1.7 to 2.0 meters.

[0025] Furthermore, after the vanadium-containing molten iron is added to the converter, its temperature is measured and its composition is sampled for analysis.

[0026] The method of this invention provides differentiated control for non-slag-discharging furnace cycles and slag-discharging furnace cycles, which can improve the oxidation rate of vanadium and reduce the carbon loss rate, thus benefiting the utilization of vanadium resources and reducing subsequent steelmaking production costs. The main function of adding vanadium-extraction coolant in the non-slag-discharging furnace cycle is to control the furnace temperature, keeping it at around 1360℃, which is beneficial for controlling vanadium oxidation and carbon loss. In the second stage, in addition to temperature control, the addition of vanadium-extraction coolant, due to its high iron oxide content, enhances the oxidizing properties of the vanadium slag at the final stage. After oxygen blowing stops, this reduces the reduction of vanadium oxides in the vanadium slag by carbon in the semi-steel, thereby reducing the vanadium content in the semi-steel. In the slag-discharging furnace cycle, the vanadium slag grade and iron content are controlled, and the coolant is still added within 3 minutes, without being added in batches.

[0027] The present invention will be further explained below with reference to specific embodiments.

[0028] Example 1

[0029] The 200t combined blowing converter used N2 for bottom blowing agitation of the permeable bricks at the bottom. After vanadium slag was removed and molten iron was added to the converter, the temperature was measured at 1320℃, and the composition of the molten iron sample was 4.20% [C] and 0.33% [V]. Oxygen blowing was used throughout the process. Based on the required final temperature of 1360℃, 42 kg / t Fe vanadium-extraction coolant was added, completed 3 minutes before blowing. 10 kg / t Fe coolant was added 0.5 minutes before the end of blowing. The final blowing temperature was 1347℃, and the residual vanadium content of the semi-steel after tapping was measured to be 0.030%.

[0030] Example 2

[0031] The 120t combined blowing converter used N2 for bottom blowing and stirring of the permeable bricks at the bottom. After the vanadium slag was removed and the molten iron was added to the converter, the temperature was measured at 1290℃, and the composition of the molten iron sample was 4.27% [C] and 0.303% [V]. Oxygen blowing was used throughout the process. According to the requirement of a final temperature of 1380℃, 32kg / tFe vanadium-extraction coolant was added, which was completed 3 minutes before blowing. 5kg / tFe coolant was added 0.5 minutes before the end of blowing. The final blowing temperature was 1367℃, and the residual vanadium content of the semi-steel after tapping was measured to be 0.027%.

[0032] Example 3

[0033] The 200t combined blowing converter used N2 for bottom blowing agitation of the permeable bricks at the bottom. After vanadium slag was removed and molten iron was added to the converter, the temperature was measured at 1320℃, and the composition of the molten iron sample was [C] 4.30% and [V] 0.331%. Oxygen blowing was used throughout the process. Based on the required final temperature of 1360℃, 44 kg / t Fe vanadium-extraction coolant was added, completed 3 minutes before blowing. 7.5 kg / t Fe coolant was added 0.5 minutes before the end of blowing. The final blowing temperature was 1345℃, and the residual vanadium content of the semi-steel after tapping was measured to be 0.028%.

[0034] Comparative Example

[0035] The 200t combined blowing converter used N2 for bottom blowing and stirring of the permeable bricks at the bottom. After the molten iron was added to the converter, the temperature was measured to be 1308℃, and the composition of the molten iron sample was 4.17% [C] and 0.329% [V]. Oxygen blowing was used for top blowing throughout the process. According to the requirement of a final temperature of 1360℃, 38kg / tFe vanadium-extracting coolant was added and added 3 minutes before blowing. The final blowing temperature was 1358℃, and the vanadium content of the semi-steel was 0.041%.

[0036] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0037] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0038] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0039] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for reducing residual vanadium at the end point of vanadium extraction in a converter, employing a production organization mode of blowing vanadium slag in 2-3 heats, wherein the multiple heats include non-slag-discharging heats and slag-discharging heats, characterized in that, In the non-slag-discharging furnace, vanadium-containing molten iron is added to the converter, and oxygen lance top blowing is used for blowing, while bottom blowing and stirring are performed at the bottom of the furnace. Based on the target temperature at the end of the blowing stage, vanadium-extracting coolant is added for the first time within 3 minutes after the start of the blowing stage. The amount of coolant added for the first time is 50% to 80% of the total amount of coolant, and the amount added for the first time is 30 to 50 kg / tFe. Vanadium-extracting coolant is added for the second time within 0.5 minutes before the end of the blowing stage, and the amount added for the second time is 5 to 10 kg / tFe. The final temperature is controlled at 1350 to 1360℃. In the slag-removing furnace cycle, the vanadium-raising coolant is added within 3 minutes before the blowing process, and steel and slag are removed after the oxygen blowing is finished.

2. The method for reducing residual vanadium at the end point of vanadium extraction in a converter according to claim 1, characterized in that, The vanadium extraction coolant includes one or more combinations of pig iron blocks, dust collector ash, iron oxide scale, and ore.

3. The method for reducing residual vanadium at the end point of vanadium extraction in a converter according to claim 1, characterized in that, The intensity of the O2 blown from the oxygen lance is 1.5–2.5 Nm. 3 / min·tFe.

4. The method for reducing residual vanadium at the end point of vanadium extraction in a converter according to claim 1, characterized in that, The gases used in bottom blowing agitation include CO2 and N2.

5. The method for reducing residual vanadium at the end point of vanadium extraction in a converter according to claim 1, characterized in that, The process involves blowing the gun at a low position in the early stage, blowing it at a high position in the middle stage, and blowing it at a low position in the later stage, with the gun position height ranging from 1.7 to 2.0 meters.

6. The method for reducing residual vanadium at the end point of vanadium extraction in a converter according to claim 1, characterized in that, After vanadium-containing molten iron is added to the converter, its temperature is measured and its composition is sampled for analysis.