A method for smelting vanadium-titanium ore in a blast furnace to improve the furnace condition recovery speed

Abstract

The present invention provides a vanadium-titanium ore blast furnace smelting method that improves the speed of furnace condition recovery. The method includes: improving the charging system, improving the furnace condition recovery system, improving the charging system, and improving the lower air supply system. The improvement of the furnace condition recovery system includes: reducing the pellet ratio when the blast furnace has abnormal furnace condition; changing the type of pellets to pellets that meet the requirements of TFe content ≥ 63%, TiO2 content ≤ 0.5%, and compressive strength ≥ 2500N / piece; and using natural lump ore that meets the requirements of TFe content ≥ 63% and TiO2 content ≤ 0.5%, with a usage ratio of 6% to 12%. The method provided by the present invention can effectively reduce the adjustment variables and adjustment amplitudes during the process of furnace condition fluctuation in vanadium-titanium magnetite blast furnace smelting, shorten the blast furnace recovery time, and promote the recovery and rapid stabilization of the blast furnace condition.

Description

Technical Field

[0001] The present invention relates to the technical field of ironmaking, and in particular to a method for smelting vanadium-titanium ore in a blast furnace for improving furnace condition recovery speed. Background Art

[0002] During the blast furnace smelting of vanadium-titanium magnetite, especially high-titanium vanadium-titanium magnetite, the TiO2 load entering the furnace is high due to its resource characteristics, and the TiO2 content in the blast furnace slag can reach 15% to 25%. In the presence of a large amount of hot coke, if the temperature is controlled too high and a certain reaction time is given, the TiO2 in the furnace is easily reduced to TiC, TiN, and its solid solution Ti(C, N), which have melting points exceeding 2900°C. The over-reduction of TiO2 is more likely to react at the slag-coke interface. The formation of high-melting-point substances will coat the coke surface, further deteriorating the permeability of the coke column and the coke's "coke window" function. At the same time, the slag of the CaO-SiO2-MgO-Al2O3-TiO2 quinary blast furnace slag with a high TiO2 content has a high melting point temperature of 1360-1400℃, which is 50-100℃ higher than the melting point of the ordinary CaO-SiO2-MgO-Al2O3 quaternary blast furnace slag. It also exhibits obvious short slag characteristics. That is, when the slag temperature drops to near the melting point, the slag viscosity will increase rapidly and lose fluidity, causing the furnace hearth to freeze. In the main tapping channel outside the blast furnace, it will also make it difficult to separate the slag and iron. The loss of metallic iron will increase significantly, and the slag and iron may even flow onto the tapping platform in front of the furnace, causing safety accidents. For these reasons, during the smelting process of vanadium-titanium magnetite blast furnace, the furnace temperature cannot be raised to around 1500℃ like the smelting of ordinary ores, nor can the furnace temperature be controlled below 1400℃. The furnace temperature control window left for blast furnace operators is often only 30-50℃, making operation more difficult.

[0003] Regarding raw material control for vanadium-titanium magnetite blast furnace smelting, the high TiO2 content in iron-containing raw materials and the high content of weaker perovskites in the main raw material sintered ore result in low blast furnace drum strength (71%-74%). Furthermore, the sintered ore has a high low-temperature pulverization rate, which can lead to poor blast furnace permeability when the sintered ore is fed to the furnace at a high ratio. The TiO2 content in vanadium-titanium pellets, another main raw material, is higher than that in vanadium-titanium sintered ore. Under current process conditions, the average compressive strength of vanadium-titanium pellets often falls below the national standard requirement of 2000N per pellet. Currently, blast furnace ironmaking generally adopts a production and smelting model with high air volume, high oxygen enrichment, high coal injection, and high smelting intensity to improve production efficiency and reduce unit energy consumption. For vanadium-titanium magnetite blast furnace smelting, accelerating the production pace can even reduce the residence time of slag with high TiO2 content in the furnace, thereby reducing the formation of high-melting-point titanium carbonitride. However, intensified smelting places even more stringent demands on raw material and fuel quality. However, the challenges of blast furnace smelting high-titanium vanadium-titanium magnetite, such as low feed grade, large slag volumes, high TiO2 content in the slag, high slag melting temperature, and low strength of the sinter and pellets, remain unresolved. This intensifies the conflict between intensified smelting and meeting raw material quality requirements, significantly increasing the difficulty of maintaining stable furnace temperature. This leads to frequent fluctuations and abnormal furnace conditions in blast furnaces producing high-titanium vanadium-titanium magnetite, along with prolonged recovery times, resulting in significant resource waste and economic losses. Another factor contributing to this long recovery time is that existing recovery strategies often involve significantly reducing or even eliminating the proportion of vanadium-titanium pellets, which have the highest TiO2 content, while increasing the proportion of vanadium-titanium sinter to reduce the TiO2 content in the slag and thus prepare for further increases in furnace temperature. In conjunction with adjustments to the charge structure, the chute distribution angle has been significantly reduced, reducing the number of ore distribution steps from 4-5 to 1, ensuring smooth airflow along the blast furnace edges. This also significantly reduces ore batch weight and coke load. Lower-stage adjustments also require significant reductions in air volume, cessation of oxygen enrichment and coal injection, lowering blast furnace smelting intensity and minimizing hearth temperature and heat fluctuations. However, to ensure sufficient heat in the hearth, the furnace temperature is often elevated, generating large amounts of high-melting-point titanium carbonitride (TiCN) within the hearth. These, combined with slag and iron, form bonds and deposits, leading to accumulation in the hearth's center and adhesion along its edges. This compresses the effective working volume, further deteriorating hearth activity and complicating blast furnace recovery. With these significant adjustments to the various upper and lower-stage adjustments, the recovery process requires significant time to reapply and adjust these adjustments, finding a balance point for stable and properly distributed gas flow. Furthermore, due to the varying time lags in the effects of various adjustments within the blast furnace, these adjustments interfere with each other, leading to a high probability of misjudging the recovery process, frequent recovery failures, and frequent relapses. Therefore, it is crucial to develop a more suitable vanadium-titanium magnetite blast furnace smelting method that reduces adjustment factors during fluctuating conditions and accelerates recovery. Summary of the Invention

[0004] In response to the aforementioned technical problem of slow furnace condition recovery in existing vanadium-titanium blast furnace smelting methods, a method for smelting vanadium-titanium blast furnaces that improves furnace condition recovery is provided. The present invention reduces adjustment factors during furnace condition fluctuations and improves furnace condition recovery.

[0005] The technical means adopted in the present invention are as follows:

[0006] A vanadium-titanium blast furnace smelting method for improving furnace condition recovery speed, comprising:

[0007] Improved charging system: TiO2 content of sintered ore used in blast furnaces is ≥5%, TiO2 content of pelleted ore is ≥8.5%, and TiO2 content of lump ore is ≤1%; TFe content of sintered ore is between 48.5% and 52%, TFe content of pelleted ore is between 52% and 54%, and TFe content of lump ore is between 40% and 48%; the proportion of sintered ore is between 55% and 78%, the proportion of pelleted ore is between 20% and 40%, and the proportion of lump ore is between 1% and 5%; TiO2 content of blast furnace slag is ≥20%;

[0008] Improvements to the furnace condition recovery system: When the blast furnace condition is abnormal, reduce the pellet ratio; change the type of pellets to pellets that meet the requirements of TFe content ≥ 63%, TiO2 content ≤ 0.5%, and compressive strength ≥ 2500N / piece; and use natural lump ore that meets the requirements of TFe ≥ 63% and TiO2 content ≤ 0.5%, with a usage ratio of 6% to 12%.

[0009] Improvements to the charging system: The charging gears are reduced from 4-5 to 3 at most, the maximum charging angle is reduced to 34-36° at most, the angle range corresponding to the charging gears is maintained at 3-4°, the difference between the maximum charging angle and the maximum charging angle is 3°, the difference between the minimum charging angle and the minimum charging angle is 4°, the charging line depth is controlled at 1.7m-1.85m, the sum of the charging ratios of the outermost gear and the second outermost gear accounts for ≥40% of the total charging ratio, and the sum of the charging ratios of the innermost gear and the second innermost gear accounts for ≥40% of the total charging ratio;

[0010] Improvement of the lower air supply system: in terms of air volume control, the air volume is met to be ≥85% of the normal air volume, and the air inlet area of the air inlet is adjusted only by adding a circle to the air inlet, so that the kinetic energy of the blast is ≥140kJ / s; the coal injection is not stopped continuously, and the coal injection adjustment is mainly used, supplemented by the wind temperature adjustment, to achieve overall control of the furnace temperature.

[0011] Furthermore, in the improvement of the furnace condition recovery system, the pellet ratio is reduced by 2% to 5%.

[0012] Furthermore, in the improvement of the furnace condition recovery system: when the blast furnace utilization coefficient of the furnace condition is ≤1.8t / (m³·d) and the air volume is ≤80% of the normal air volume, natural lump ore is used at the same time as ferromanganese ore with a low TFe content of 2% and a Mn content ≥18%.

[0013] Furthermore, in the improvement of the lower air supply system, the TiO2 content of the slag is controlled to 13%~15%, the R2 of the slag is controlled to 0.98~1.05, and the molten iron content is controlled to 0.6%~0.8%.

[0014] Furthermore, the abnormal furnace conditions include disordered coal gas flow distribution, asymmetric relationship between blast furnace air volume and air pressure, significant changes and bifurcation in the static pressure ratio of the upper and lower layers, and pipeline travel in the blast furnace.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The improved charging system and furnace condition recovery system provided by the present invention, compared with the existing method for adjusting the charge structure when recovering from furnace condition fluctuations, can achieve a relatively stable charge structure with a small fluctuation range. The existing method reduces the pellet ratio to 10%, or even eliminates pellets, while the present method only adjusts it by 2-5 percentage points; the present method can significantly improve the comprehensive iron grade of the blast furnace input. The existing method reduces the comprehensive input TFe from 51%-52% to 47%-50%, while the present method increases the comprehensive charge TFe to 55%-57%; the present method can significantly reduce the amount of blast furnace slag. The existing method increases the slag amount to more than 700kg / t iron, while the present method reduces the slag amount to 400-450kg / t iron; the present method makes it easier to obtain slag with lower TiO2. The existing method eliminates the use of vanadium-titanium pellets, and the TiO2 content of the slag can only be reduced to 14.5%-16%. The present method can reduce the TiO2 content of the slag to 13%-14%;

[0017] 2. Regarding charge reduction properties, the high-iron-grade lump ore used in this method has a higher melting dripping temperature than the low-grade lump ore used. This helps maintain a low melting zone during furnace recovery, preventing the upward shift of the melting zone caused by using an excessively high proportion of low-grade lump ore, which would further impair charge heat exchange and indirect reduction. This also avoids a significant increase in slag volume and deterioration in blast furnace permeability due to a decrease in overall iron grade. Low-titanium pellets also have a wider source of raw materials, and their particle size is more uniform than that of sintered ore, further enhancing blast furnace permeability.

[0018] 3. The improved method for the charging system provided by the present invention ensures that there is sufficient coke at the edge and center of the blast furnace throat, forming a coke peak during the charging process, preventing the ore from rolling excessively toward the edge and center of the throat during the charging process, while also ensuring that the ore has a certain distribution width band, reducing the rolling effect of the ore, thereby ensuring that the ore-to-coke ratio at the edge and center of the blast furnace throat is small, achieving the goals of open airflow paths at the edge and center of the blast furnace, making it easy for the blast furnace to accept air volume, and also making it easy to maintain a certain air volume. At the same time, the ore batch weight and coke batch weight are adjusted according to the air volume, using the ore batch weight to coke batch weight ratio as a flexible adjustment method; avoiding excessive opening of the edge airflow caused by large adjustments to the charging angle and the number of charging gears, which significantly reduces the gas utilization rate and significantly increases the furnace temperature fluctuation, and at the same time avoids increasing the difficulty and uncertainty of the gas flow distribution reformation during the air addition process.

[0019] 4. The improved method of the lower air supply system provided by the present invention reduces the TiO2 content in the slag and the binary basicity R2 in the slag by ensuring a certain air volume, thereby improving the fluidity of the slag and ensuring that the TiO2 in the slag is not excessively reduced to form titanium carbonitride, thereby reducing the amount of high-melting-point adhesives in the furnace hearth; on the basis of adjusting the charge structure, the charging grade is improved, the slag amount is reduced, and the air permeability of the blast furnace is ensured; while ensuring the air volume and charging grade, a certain iron output is guaranteed, and the adhesives in the furnace hearth are flushed and melted by continuously generated molten iron with a viscosity far lower than that of the slag, thereby removing as much high-melting-point material as possible and avoiding serious accumulation in the center of the furnace hearth and adhesion at the edge. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0026] like Figure 1 As shown, the present invention provides a vanadium-titanium blast furnace smelting method for improving the furnace condition recovery speed, including: charging system improvement, furnace condition recovery system improvement, material distribution system improvement and lower air supply system improvement.

[0027] During the daily production process of vanadium-titanium magnetite smelting in blast furnaces, the TiO2 content of blast furnace slag is ≥20%, the TiO2 content of sintered ore used in the blast furnace is ≥5%, the TiO2 content of pellets is ≥8.5%, and the TiO2 content of lump ore is ≤1%. The TFe content of sintered ore is between 48.5% and 52%, the TFe content of pellets is between 52% and 54%, and the TFe content of lump ore is between 40% and 48%. The sintered ore mix is between 55% and 78%, the pellet mix is between 20% and 40%, and the lump mix is between 1% and 5%. This is especially true when the blast furnace experiences significant gas flow distribution disturbances, an asymmetric relationship between blast furnace air volume and pressure, a significant change and bifurcation in the static pressure ratio between the upper and lower layers, or pipe travel in the blast furnace, and the blast furnace is forced to reduce air flow to adjust the gas flow distribution. The blast furnace will no longer significantly reduce the proportion of vanadium-titanium pellets, nor will it use the stopped furnace block ore with low TFe content (40%~48%) and high FeO content (20%~22%); the method of restoring the furnace condition is changed to: only make a small adjustment to the pellet ratio (reduction of 2%~5%), change the type of pellets, and use pellets that meet the requirements of TFe content ≥63%, TiO2 content ≤0.5%, and compressive strength ≥2500N / piece; in the use of natural block ore, use natural block ore that meets the requirements of TFe ≥63% and TiO2 content ≤0.5%, with a usage ratio of 6%~12%. In the case of deteriorating furnace conditions, 2% iron-manganese ore with low TFe content and high Mn content can be used at the same time. Compared with the existing method of adjusting the charge structure when the furnace condition fluctuates and recovers, this method can achieve a relatively stable charge structure with a small fluctuation range (the existing method reduces the pellet ratio to 10%, or even eliminates pellets, while this method only adjusts it by 2 to 5 percentage points), significantly improves the comprehensive iron grade of the blast furnace (the existing method reduces the comprehensive charge TFe from 51% to 52% to 47% to 50%, while this method increases the comprehensive charge TFe to 55% to 57%), and significantly reduces the amount of blast furnace slag (the existing method increases the slag amount to more than 700kg / t iron, while the existing method increases the slag amount to more than 100kg / t iron). The content of TiO2 in the slag is reduced to 400~450kg / t iron), and it is easier to obtain slag with lower TiO2 (the original method eliminates the use of vanadium-titanium pellets, and the TiO2 content of the slag can be reduced to 14.5%~16%. The TiO2 content of the slag in this method can be reduced to 13%~14%). Although the FeO content of the high-TFe content lump ore used in this method is lower than that of the original low-grade lump ore, during the blast furnace smelting process, as the ore heats up and is reduced, the large amount of Fe2O3 and Fe4O3 originally present in the ore will generate more FeO or Fe xO, and also does not affect the FeO content in the primary slag and intermediate slag during the slag-making process. Therefore, the present method can also achieve the purpose of reducing the TiO2 content in the slag, increasing the FeO content in the slag, and improving the fluidity of the slag as in the original method. At the same time, it also reduces the amount of slag, stabilizes the structure of the charge, and improves the overall compressive strength of the blast furnace charge. Furthermore, in terms of the reduction properties of the charge, the soft melting dripping temperature of the high-iron-grade lump ore is higher than that of the low-grade lump ore used, which helps to maintain a low soft melting zone position during the furnace condition recovery process, avoids the use of too high a proportion of low-grade lump ore causing the soft melting zone to move upward, further leading to a deterioration in the heat exchange and indirect reduction effects of the charge; it also avoids a significant increase in slag volume due to a reduction in the overall iron grade, which deteriorates the blast furnace permeability. The source of raw materials for low-titanium pellets is also more extensive, and the pellet size is more uniform than that of sintered ore, which is also more conducive to maintaining the permeability of the blast furnace.

[0028] Furthermore, in order to cooperate with the adjustment and use of the charge structure, the charge system requires that the ore distribution gear be reduced from 4-5 gears to 3 gears at most, the maximum ore distribution angle be reduced to 34-36° at most, the angle range corresponding to the ore distribution gear is maintained at 3-4°, the difference between the maximum coking angle and the maximum ore distribution angle is 3°, the difference between the minimum ore distribution angle and the minimum coking angle is 4°, the control material line depth is 1.7m-1.85m, the sum of the coking ratios of the outermost gear and the second outermost gear accounts for ≥40% of the total coking ratio, and the sum of the coking ratios of the innermost gear and the second innermost gear accounts for ≥40% of the total coking ratio. Through the above-mentioned distribution system control, it is ensured that there is enough coke at the edge and center of the blast furnace throat, and a coke pile is formed during the distribution process, which prevents the ore from rolling too much to the edge and center of the furnace throat during the distribution process. At the same time, it is ensured that the ore has a certain distribution width band to reduce the rolling effect of the ore, thereby ensuring that the ore-coke ratio at the edge and center of the blast furnace throat is small, achieving the purpose of opening the airflow passages at the edge and center of the blast furnace, making it easy for the blast furnace to accept air volume, and also easy to maintain a certain air volume. At the same time, the ore batch weight and coke batch weight are adjusted according to the air volume, and the ore batch weight and coke batch weight ratio are used as a flexible adjustment method; avoid excessive opening of the edge airflow caused by large adjustments in the distribution angle and the number of distribution gears, which will greatly reduce the gas utilization rate and increase the furnace temperature fluctuation. At the same time, avoid increasing the difficulty and uncertainty of the gas flow distribution reform during the air addition process.

[0029] Regarding the lower air supply system, air volume control maintains a nominal air volume of ≥85%. Adjustment of the tuyere inlet area is achieved solely through the addition of rings to the tuyere, ensuring a blast energy of ≥140 kJ / s. Furthermore, pulverized coal injection (CPI) is discontinued, ensuring its use as a flexible means of lower-level adjustment, primarily through CPI, supplemented by air temperature control, to achieve overall furnace temperature control. Through the coordinated adjustments of the upper charging system and the lower air supply system, the TiO2 content in the slag is controlled at 13%-15%, the R2 (CaO / SiO2 mass ratio) in the slag is controlled at 0.98-1.05, and the [Ti+Si] content in the hot metal is controlled at 0.6%-0.8%. By ensuring a certain air volume, reducing the TiO2 content in the slag, reducing the binary basicity R2 of the slag, improving the fluidity of the slag, and ensuring that the TiO2 in the slag is not excessively reduced to form titanium carbonitride, the amount of high-melting-point adhesives in the furnace hearth is reduced; on the basis of adjusting the charge structure, the incoming furnace grade is improved, the slag amount is reduced, and the air permeability of the blast furnace is guaranteed; while ensuring the air volume and incoming furnace grade, a certain iron output is guaranteed, relying on the continuously generated molten iron with a viscosity much lower than that of the slag (molten iron viscosity 0.001~0.01Pa·S, slag viscosity 0.2~0.5Pa·S) to flush and melt the adhesives in the furnace hearth, bringing out as much high-melting-point material as possible, and avoiding serious accumulation in the center of the furnace hearth and adhesion at the edge. Smelt under this condition for 2 to 7 days, wait until the blast furnace airflow is completely stabilized and the air volume is fully restored, and the charging system is advanced to the 4th gear charging system, then gradually replace the ordinary pellets with vanadium-titanium pellets, increase the TiO2 content of the slag, and finally gradually reduce the high iron grade lump ore, returning to the normal production charge structure and system.

[0030] Example 1

[0031] A vanadium-titanium blast furnace smelting method for improving furnace condition recovery speed is disclosed. Blast furnace A uses high-titanium vanadium-titanium magnetite as the main raw material. During stable and forward production, the charge structure used is 63% sintered ore + 35% pellets + 2% lump ore. The TiO2 content of the sintered ore is 5.2%, the TiO2 content of the pellets is 9.6%, the TiO2 content of the lump ore is 0.3%, the TiO2 content of the slag is 21.6%, the binary basicity R2 of the slag is 1.08-1.10, the blast furnace utilization coefficient is 2.56t / (m³·d), and the fuel ratio is 545kg / t. Due to the long-term use of a material system with heavy edge airflow suppression:

[0032] ,

[0033] Ore batch weight reached 44t / batch, and coke load reached 4.35t / t. Despite a blast furnace gas utilization rate exceeding 44.5%, the furnace throat temperature remained chronically low, at only around 60°C. After five months of continuous smelting, in March 2021, following a blast break to replace a faulty tuyeres, airflow became turbulent, with frequent surges and bifurcations in the furnace body static pressure. Local piping trips in the blast furnace were frequent, forcing the furnace to reduce airflow, with average air volume dropping from 4100m³ / min to 3600m³ / min, and the blast furnace utilization factor dropping to around 1.6 t / (m³·d). In view of the historical lessons learned from dealing with fluctuations in blast furnace conditions, measures such as a significant reduction in the distribution angle, the reduction in the ore distribution gear to gear 2 or 1, the reduction and elimination of the proportion of vanadium-titanium pellets, a significant increase in the proportion of low-grade, high-FeO lump ore, the reduction of slag TiO2 to 14-15%, and the increase of furnace temperature to a level where the [Ti+Si] content of molten iron is ≥ 0.9% have resulted in a serious change in the blast furnace airflow distribution, a significant reduction in gas utilization, and a sharp increase in furnace temperature volatility. During the slag and iron tapping process, the furnace temperature is prone to repeated cooling and heating. The blast furnace is forced to repeatedly reduce air flow, which significantly prolongs the time for furnace condition recovery. In the end, the furnace condition is even difficult to recover, resulting in a huge waste of resources and economic losses. Therefore, when the furnace condition fluctuated, the ash content of the furnace condition was adjusted. At the beginning of the furnace condition decline, high iron grade, low titanium pellets and lump ore were actively purchased. The TFe content of the pellets reached 64.5%, the TiO2 content was 0.1%, and the average compressive strength reached 2800N / piece. The TFe content of the lump ore reached 63.5%, and the TiO2 content was 0.2%. In terms of operation, the feeding angle was gradually reduced, but the basic feeding system of 3 gears was maintained. The commonly used feeding system is:

[0034] ,

[0035] By flexibly changing the ore batch weight and coke load, using 32% low-titanium pellets + 10% high-iron lump ore, the TiO2 content in the slag was reduced to 13.5%-14%. Although the gas utilization rate dropped to about 41% after the development of the edge and center airflows, as the comprehensive iron grade of the charge increased to 56.2%, the air volume was maintained at about 3600 m³ / min, ensuring a certain amount of iron. The slag-iron ratio was reduced from 610 kg / t to 455 kg / t. The blast furnace airflow distribution was stabilized two days after the charge structure was changed, and then gradually improved. On the fourth day, the air volume was increased to 4000 m³ / min, and the ore distribution gear was restored to gear 4, but the maximum coke distribution angle was limited to 39.5°, and the maximum ore distribution angle was 36.5°. The blast furnace utilization coefficient was restored to 2.1 t / (m³·d), the fuel ratio was also reduced from 590 kg / t to 550 kg / t, and the furnace condition was basically restored. By the sixth day of smelting, the furnace condition had stabilized, and the blast furnace utilization factor reached 2.45 t / (m³·d). The pellets were gradually changed to vanadium-titanium pellets, the lump ore ratio was reduced to 3%, and low-grade lump ore was used. After one day of smelting, all operating systems were stabilized and controlled, and the blast furnace returned to normal production and smelting.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vanadium-titanium blast furnace smelting method for improving furnace condition recovery speed, characterized in that: include: Improved charging system: TiO2 content of sintered ore used in blast furnaces is ≥5%, TiO2 content of pelleted ore is ≥8.5%, and TiO2 content of lump ore is ≤1%; TFe content of sintered ore is between 48.5% and 52%, TFe content of pelleted ore is between 52% and 54%, and TFe content of lump ore is between 40% and 48%; the proportion of sintered ore is between 55% and 78%, the proportion of pelleted ore is between 20% and 40%, and the proportion of lump ore is between 1% and 5%; TiO2 content of blast furnace slag is ≥20%; Improvements to the furnace condition recovery system: When the blast furnace condition is abnormal, reduce the pellet ratio by 2% to 5%; change the type of pellets to pellets that meet the requirements of TFe content ≥ 63%, TiO2 content ≤ 0.5%, and compressive strength ≥ 2500N / piece; and use natural lump ore that meets the requirements of TFe ≥ 63% and TiO2 content ≤ 0.5%, with a usage ratio of 6% to 12%; Improvements to the charging system: The charging gears are reduced from 4-5 to 3 at most, the maximum charging angle is reduced to 34-36° at most, the angle range corresponding to the charging gears is maintained at 3-4°, the difference between the maximum charging angle and the maximum charging angle is 3°, the difference between the minimum charging angle and the minimum charging angle is 4°, the charging line depth is controlled at 1.7m-1.85m, the sum of the charging ratios of the outermost gear and the second outermost gear accounts for ≥40% of the total charging ratio, and the sum of the charging ratios of the innermost gear and the second innermost gear accounts for ≥40% of the total charging ratio; Improvement of the lower air supply system: in terms of air volume control, the air volume is met to be ≥85% of the normal air volume, and the air inlet area of the air inlet is adjusted only by adding a circle to the air inlet, so that the kinetic energy of the blast is ≥140kJ / s; the coal injection is not stopped continuously, and the coal injection adjustment is mainly used, supplemented by the wind temperature adjustment, to achieve overall control of the furnace temperature.

2. The method for smelting vanadium-titanium ore in a blast furnace to improve furnace condition recovery speed according to claim 1, characterized in that: In the improvement of the furnace condition recovery system: when the blast furnace utilization coefficient of the furnace condition is ≤1.8t / (m³·d) and the air volume is ≤80% of the normal air volume, natural lump ore is used at the same time as ferromanganese ore with a low TFe content of 2% and a Mn content ≥18%.

3. The method for smelting vanadium-titanium ore in a blast furnace to improve furnace condition recovery speed according to claim 1, characterized in that: In the improvement of the lower air supply system, the TiO2 content of the slag is controlled to 13%~15%, the R2 of the slag is controlled to 0.98~1.05, and the molten iron content is controlled to 0.6%~0.8%.

4. The method for smelting vanadium-titanium ore in a blast furnace to improve furnace condition recovery speed according to claim 1, characterized in that: The abnormal furnace conditions include disordered coal gas flow distribution, asymmetric relationship between blast furnace air volume and air pressure, large changes and bifurcations in the static pressure ratio of the upper and lower layers, and pipeline travel in the blast furnace.

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