Blast furnace oxygen-enriched coal injection smelting method

Abstract

The invention relates to the technical field of ferrous metallurgy, and discloses a blast furnace oxygen-enriched coal injection smelting method which is characterized in that the oxygen-enriched rate and coal ratio parameters in blast furnace smelting are adjusted according to the rule that the coal ratio is increased by 10-14 kg / tFe every time the oxygen-enriched rate is increased by 1%. According to the method, the balance problem of the oxygen enrichment amount and the coal injection amount is solved, an appropriate oxygen enrichment coal injection interval for blast furnace smelting is found, and the oxygen enrichment coal injection amount is increased under the condition that smooth operation of the blast furnace is guaranteed, so that the coke ratio of the blast furnace is reduced, pollution emission is reduced, and the national overall requirement for the iron and steel industry is met; meanwhile, the blast furnace yield index is improved, and the smelting cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of iron and steel metallurgy, and in particular to a blast furnace oxygen-enriched coal injection smelting method. Background Art

[0002] Pulverized coal injection in blast furnaces is an effective way to reduce the coke ratio. Replacing some metallurgical coke with inexpensive pulverized coal can significantly reduce pig iron costs. However, excessive injection rates can cause unburned coal to block the coke window and carbon deposits in the hearth, hindering smooth operation of the blast furnace. Oxygen-enriched blast, which adds industrial oxygen to the blast furnace air to increase the oxygen content above atmospheric oxygen, can effectively increase smelting intensity and output, but this effect decreases with increasing oxygen enrichment. Research and practice have shown that due to the significant complementary effects of pulverized coal injection and oxygen enrichment on the blast furnace smelting process, the combined process of pulverized coal injection and oxygen-enriched blast has been widely used in blast furnace production and has become one of the main technical measures for energy conservation and consumption reduction in the ironmaking process. The combination of oxygen-enriched blast and pulverized coal injection in blast furnace production can not only intensify smelting but also significantly save coke, making it an energy-saving, emission-reduction, and low-carbon green technology for modern blast furnace ironmaking.

[0003] Oxygen-enriched blast involves adding industrial oxygen to the hot air before it enters the blast furnace, increasing its oxygen content to a level exceeding that of atmospheric oxygen. The yield-increasing effect of oxygen enrichment follows a diminishing trend: as the oxygen enrichment rate increases, the yield increase for each 1% of oxygen enrichment decreases. For example, when the oxygen content of the air in the blast inlet is 21% to 25% during production, each 1% increase in O2 increases production by 3.2% to 3.5%; when the oxygen content is 25% to 30%, each 1% increase in O2 increases production by 3%; when the oxygen content is 30% to 35%, each 1% increase in O2 increases production by 2.7%; and when the oxygen enrichment reaches 40%, each 1% increase in O2 increases production by less than 2.4%. Practical experience shows that as oxygen levels increase, the amount of molten iron added decreases, and fuel consumption also increases to a certain extent. Therefore, there is an optimal oxygen enrichment rate for oxygen-enriched coal injection in blast furnaces. However, numerous scientific studies and industrial experiments have shown that increasing oxygen enrichment can also introduce new challenges to blast furnace smelting. Exceeding a certain oxygen enrichment rate will result in insufficient gas flow within the furnace, causing insufficient heating of the furnace charge, severely hindering furnace reduction, and significantly reducing the degree of indirect reduction. Excessively high oxygen enrichment rates can increase theoretical combustion temperatures, reduce hearth gas flow, and lower direct reduction rates, leading to excessively high hearth temperatures, ultimately causing a rapid increase in the blast furnace fuel ratio and poor furnace conditions.

[0004] Under zero oxygen enrichment conditions, if the pulverized coal injection rate exceeds a certain range, the decomposition of the pulverized coal absorbs heat and generates increased gas, leading to a decrease in the theoretical combustion temperature at the tuyere and insufficient furnace hearth temperature. Furthermore, the increased gas volume and decreased coke ratio also lead to poor charge permeability. Production practice has demonstrated that when the air temperature reaches 1000°C, under no oxygen enrichment conditions, the pulverized coal injection rate should not exceed 100kg per ton of iron. Therefore, as the pulverized coal injection rate increases, sufficient oxygen is required to promote pulverized coal combustion, improve the coal-coke replacement ratio, and ensure smooth operation of the blast furnace.

[0005] Oxygen enrichment and coal injection in blast furnaces are mutually dependent and conditional. However, achieving a balanced balance in industrial production is challenging, especially when oxygen enrichment rates exceed 10%. Regulating the relationship between oxygen enrichment and coal injection requires extensive experimentation and exploration. Only by achieving a balanced balance between oxygen enrichment and coal injection can we fully master oxygen-enriched blast furnace smelting technology. Summary of the Invention

[0006] In view of this, in order to address the problems existing in the above-mentioned prior art, the present invention provides a blast furnace oxygen-enriched coal injection smelting method to solve the problem of the balance between oxygen enrichment and coal injection, find the appropriate oxygen-enriched coal injection range for blast furnace smelting, and thus achieve the purpose of reducing smelting costs.

[0007] To solve the above technical problems, the technical solution of the present invention provides a blast furnace oxygen-enriched coal injection smelting method, which adjusts the oxygen enrichment rate and coal ratio parameters in blast furnace smelting according to the rule that for every 1% increase in oxygen enrichment rate, the coal ratio increases by 10-14kg / tFe.

[0008] Even better, the oxygen enrichment rate and coal ratio parameters in blast furnace smelting are adjusted according to the rule that for every 1% increase in oxygen enrichment rate, the coal ratio increases by 12.5kg / tFe.

[0009] With reference to the above-mentioned rules for improving oxygen enrichment rate and coal ratio, in some technical solutions of the present invention, the blast furnace is operated at an oxygen enrichment rate of 12500 Nm 3 / h, and the coal injection rate is 26t / h for smelting.

[0010] The present invention collects technical indicator parameters of normal blast furnace production, calculates the bosh gas volume with reference to Formula I, calculates the air permeability resistance coefficient with reference to Formula II, and calculates the theoretical combustion temperature with reference to Formula III. According to the calculation results, linear relationships between the oxygen enrichment rate and the coal ratio and the bosh gas volume, the air permeability resistance coefficient, and the theoretical combustion temperature are obtained, and then, according to the linear relationship, the relationship between the oxygen enrichment rate and the coal ratio is calculated as follows: for every 1% increase in the oxygen enrichment rate, the coal ratio is reasonably increased by 10-14 kg / tFe, and the optimal coal ratio increase is 12.5 kg / tFe.

[0011] About Bosh Gas Volume V BG The empirical formula for calculation is as follows:

[0012]

[0013] Where V B -Air volume (excluding oxygen enrichment), Nm 3 / min; V O2 -Oxygen enrichment, Nm 3 / min; W B -Humidity, g / Nm 3 ;P C -Amount of pulverized coal injected, kg / h; H-hydrogen content of pulverized coal, %.

[0014] About Bosh Gas Volume V BG It is generally believed that the coal generated in the circulation zone enters the furnace after leaving the circulation zone, so the amount of gas in the furnace is the amount of gas in the circulation zone. Therefore, the volume change of gas generated by the tuyere wind and the combustion of the front coke and injected fuel determines V BG The numerical value of .

[0015] The tuyere combustion zone is the source of blast furnace gas. The combustion of coke and carbon in the injected fuel, and the reaction between the air and H₂O in the injected fuel and carbon, determine changes in gas composition and volume. Because the combustion zone has the highest temperature and a relative excess of carbon, it can be considered that the H₂O and O₂ in the blast air, as well as the H₂O in the injected fuel, are completely consumed during the reaction, resulting in CO and H₂ as the products. Therefore, the following equations apply:

[0016] C reacts with O2 in the blast

[0017] 2C+O2=2CO

[0018] C reacts with H2O in the blast air and injected fuel

[0019] C+H20=CO+H2

[0020] The reaction equation shows that the first term is the sum of the volume of air in the blast furnace after entering the blast furnace and the volume of gas increased by the combustion of O2 in the air; the last three terms are the changes in gas volume caused by the combustion of O2 and H2O in the blast furnace. The volume of CO produced by the combustion of O2 per unit volume should be twice the volume of O2, even if the gas volume increase should be equal to V O2 Therefore, the coefficient in the second term should be 1. If the percentage of hydrogen content in pulverized coal is directly included in the fourth term, it should be multiplied by 100%. Therefore, it is more reasonable to calculate the amount of bosh gas according to Formula I.

[0021]

[0022] The air resistance coefficient K is calculated according to the empirical formula II, and the theoretical combustion temperature T f Calculated according to empirical formula III.

[0023]

[0024] In formula II, P B -wind pressure, kPa; P T -Top pressure, kPa; X BG - Bosh gas volume, m 3 / min.

[0025] T f =1570+0.8T1+4.37f×10 / 0.785-5.85W-2.5×10 6 ×M / (Q×60) (Ⅲ),

[0026] In formula III, T1 is wind temperature, °C; f is oxygen enrichment rate, %; W is humidity, g / m 3 ;M-coal injection rate, t / h;Q-air volume, km 3 / min.

[0027] Furthermore, in the above technical solution, the coke load of blast furnace smelting is ≥4.65. According to the present invention, experiments have found that when high coal injection is used, the coke load increases and the coke consumption decreases, which is beneficial to reducing production costs.

[0028] Furthermore, in the above technical solution, an oxygen-enriched operation mode with a stable air volume is adopted. It is well known to those skilled in the art that blast furnace oxygen-enriched blast can be summarized into three operation modes: (1) maintaining the air volume unchanged and increasing the oxygen input, i.e., oxygen-enriched operation with a stable air volume; (2) increasing the oxygen input and reducing the air volume to maintain the stability of the furnace gas volume, i.e., oxygen-enriched operation with a stable furnace gas volume; (3) maintaining the oxygen volume unchanged and reducing the air volume to cope with the increase in the pressure difference in the furnace, so that the pressure difference is relatively stable to maintain the furnace condition, i.e., oxygen-enriched operation with a stable pressure difference. In blast furnace ironmaking, high production capacity and economic benefits are achieved under the premise of stable furnace condition, and different oxygen-enriched operation modes have different effects on furnace condition stability and high production capacity. Under oxygen-enriched operation with a stable air volume, despite relatively large bosh gas volumes, it offers high blast kinetic energy, excellent swirl zone operation, and increased permeability to air and liquid in the dripping zone. These characteristics significantly contribute to addressing high-capacity and smooth-running blast furnace issues, such as increased material flow within the furnace. This makes it a preferred oxygen-enriched operation method for high-capacity blast furnaces. When the blast volume remains constant, increasing the blast oxygen enrichment rate increases the amount of carbon burned in front of the tuyere, raising the theoretical combustion temperature accordingly. Maintaining a high oxygen enrichment rate and high air temperature not only ensures the appropriate theoretical combustion temperature in front of the tuyere required for large-scale coal injection, improving the pulverized coal combustion rate, but also significantly impacts the slag formation zone within the furnace.

[0029] Furthermore, in the above technical solution, a mixture of high-ash pulverized coal and low-ash pulverized coal is injected, where the high-ash pulverized coal has an ash content of ≥25% and the low-ash pulverized coal has an ash content of ≤10%. The high ash content of high-ash pulverized coal limits the increase in the coal ratio. While low-ash pulverized coal can increase the coal ratio, it has a high displacement ratio and, even after increasing the coal ratio, still does not burn fully. This results in poor slag fluidity, unstable forward flow, and unstable upper coal flow, which can easily lead to sudden collapse of suspended material. However, using a mixed coal mixture improves the combustion rate of the pulverized coal and improves forward flow.

[0030] Furthermore, in the above technical solution, the blast furnace top pressure is controlled to be ≥65kPa. When the coal ratio is increased, the gas volume increases, making it difficult to stabilize the upper gas flow. Increasing the furnace pressure can stabilize the gas flow and improve gas utilization.

[0031] Furthermore, in the above technical solution, the blast furnace iron yield is ≥15 times / day. Increasing the iron yield can accommodate increased blast furnace smelting intensity, which continues to increase with increasing oxygen enrichment and coal ratio. If the iron yield is too low, severe pressure buildup before slag tapping, uneven material flow, and rising slag surface can lead to increased unburned coal in the slag, making the slag sticky. Increasing ferromagnetism can reduce this pressure buildup before slag tapping and improve air permeability.

[0032] Compared with existing technologies, the blast furnace oxygen-enriched coal injection smelting method provided by this invention solves the problem of balancing the amount of oxygen enrichment and coal injection, identifies the appropriate oxygen-enriched coal injection range for blast furnace smelting, and increases the amount of oxygen-enriched coal injection while ensuring smooth blast furnace operation. With this increased oxygen-enriched coal injection rate, the blast furnace coke ratio is reduced, saving coke and reducing pollution emissions, meeting the overall national requirements for the steel industry. It also improves blast furnace output indicators and reduces smelting costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a relationship diagram of the effect of oxygen-enriched coal injection on the amount of bosh gas in Example 1;

[0034] Figure 2 This is a relationship diagram of the effect of oxygen-enriched coal injection on the air permeability resistance coefficient in Example 1;

[0035] Figure 3 This is a relationship diagram of the effect of oxygen-enriched coal injection on the theoretical combustion temperature in Example 1;

[0036] Figure 4 2 is a trend diagram of the change of oxygen enrichment over time in Example 2;

[0037] Figure 5 The figure is a trend diagram of the coal injection amount changing with time in Example 2;

[0038] Figure 6 The figure is a trend diagram of the change of the ore batch weight over time in Example 2;

[0039] Figure 7 This is a trend chart of blast furnace output over time in Example 2;

[0040] Figure 8 This is a graph showing the changing trend of coal injection amount before and after the coke load changes in Example 2. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example 1: Exploring the improvement rules of oxygen enrichment rate and coal ratio

[0043] Refer to formula I to calculate the amount of furnace gas, refer to formula II to calculate the air permeability resistance coefficient, and refer to formula III to calculate the theoretical combustion temperature.

[0044]

[0045] In Formula I, V B -Air volume (excluding oxygen enrichment), Nm 3 / min; V O2 -Oxygen enrichment, Nm 3 / min; W B -Humidity, g / Nm 3 ;P C -Amount of pulverized coal injected, kg / h; H-hydrogen content of pulverized coal, %.

[0046]

[0047] In formula II, P B -wind pressure, kPa; P T -Top pressure, kPa; X BG - Bosh gas volume, m 3 / min.

[0048] T f =1570+0.8T1+4.37f×10 / 0.785-5.85W-2.5×10 6 ×M / (Q×60) (Ⅲ),

[0049] In formula III, T1 is wind temperature, °C; f is oxygen enrichment rate, %; W is humidity, g / m 3 ;M-coal injection rate, t / h;Q-air volume, km 3 / min.

[0050] When raw material and fuel conditions are constant, the initial temperature and composition of the pre-tuyere gas are relatively stable. Assuming the gas consumption per ton of pig iron is essentially constant, the bosh gas volume becomes a key factor affecting production. Appropriately increasing the bosh gas volume helps accelerate the smelting process, improve smelting intensity and pig iron production, and facilitate smooth blast furnace operation. However, excessive bosh gas volume can cause fluidization and flooding, leading to adverse consequences such as suspended material and pipework. Oxygen enrichment in the blast furnace increases the oxygen concentration and relatively decreases the nitrogen concentration in the blast air, reducing the air consumption per unit mass of carbon burned and, consequently, reducing the gas volume generated by pre-tuyere combustion. The reaction products of hydrocarbons in the injected pulverized coal are CO and low-density H₂. Therefore, pulverized coal injection increases gas volume and expands the combustion zone. While maintaining stable furnace conditions and a constant fuel ratio, oxygen enrichment combined with pulverized coal injection can maintain a relatively stable bosh gas volume while accelerating carbon combustion in the tuyere combustion zone. This increases the amount of reducing gases in the gas, facilitating indirect reduction. In addition, the density and viscosity of H2 in coal gas are both small, and its penetration ability is greater than that of CO, which is more conducive to maintaining the active state of the furnace.

[0051] The relationship between oxygen-enriched coal injection and the amount of bosh gas is calculated and can be found in Figure 1 As shown, according to Figure 1 It can be calculated that the linear relationship between the bosh gas volume (y) and the oxygen enrichment rate (x) is: y = 1911x + 10325, and the linear relationship between the bosh gas volume (y) and the coal ratio (x) is: y = 2.84x + 4937.

[0052] Depend on Figure 1 It can be seen that oxygen enrichment and coal injection have opposite effects on the amount of gas in the furnace. The amount of gas in the furnace decreases with the increase of oxygen enrichment and increases with the increase of coal ratio. The results of calculating the effects of oxygen enrichment and coal ratio on the amount of gas in the furnace show that for every 1% increase in oxygen enrichment, the amount of gas in the furnace decreases by about 12m3. 3 / min,; for every 1kg / t increase in coal ratio, the amount of bosh gas increases by about 1.1m 3 / min. Therefore, the impact of increasing oxygen enrichment by 1% on bosh gas volume is roughly equivalent to increasing the coal ratio by 10kg / t. Assuming a pulverized coal combustion rate of 80%, a 1% oxygen enrichment increase in the coal ratio creates approximately 12.5kg / t of space. Therefore, the proper combination of oxygen enrichment and coal injection can directly reduce the coke ratio.

[0053] The air resistance coefficient, K, is a parameter related to top pressure, wind pressure, and bosh gas volume. It reflects, to a certain extent, the relative movement of charge and gas within the blast furnace and the permeability of the charge column, thus predicting blast furnace conditions. A larger air resistance coefficient indicates increased resistance to charge descent, a larger pressure differential, and poorer charge column permeability, potentially leading to suspended charge. A too small air resistance coefficient results in excessively fast gas flow, poor indirect reduction and gas utilization, reduced blast furnace energy efficiency, and an increased fuel ratio.

[0054] The relationship between the influence of oxygen-enriched coal injection on the air permeability resistance coefficient is calculated by referring to Figure 2 As shown, according to Figure 2 It can be calculated that the linear relationship between the air resistance coefficient (y) and the oxygen enrichment rate (x) is: y = 2.55x-2.34, and the linear relationship between the air resistance coefficient (y) and the coal ratio (x) is: y = -0.003x+4.854.

[0055] Depend on Figure 2 It can be seen that the K value increases with increasing oxygen enrichment and decreases with increasing coal ratio, but the fluctuation range is small and relatively stable, which can also reflect the current stable state of the blast furnace. Increasing oxygen enrichment leads to an increase in the K value. Since oxygen enrichment can significantly increase the theoretical combustion temperature, excessively high theoretical combustion temperatures can also lead to smelting difficulties and increase the pressure difference, causing the K value to rise. It is worth noting that within the current calculation range, the K value decreases with increasing coal ratio. This is because when the K value is within a reasonable range, the permeability of the material column is good, creating conditions for increasing the coal ratio. However, as the coal ratio continues to increase, due to the influence of the replacement ratio and the decrease in the combustion rate of the pulverized coal in front of the tuyere, unburned coal is prone to carbon deposition. Some unburned coal enters with the coal gas and blocks the coke window, causing the permeability of the material column to deteriorate and the K value to increase. At this time, it is not advisable to continue to increase the coal ratio.

[0056] Theoretical Combustion Temperature: Combustion in the combustion zone is generally considered a constant-pressure adiabatic process. Therefore, the theoretical combustion temperature is the temperature that the system can reach after the incomplete combustion of the carbon in front of the tuyere, the injected fuel, and the H2O in the blast air, all of the heat generated is used to heat the reaction products. As can be seen from the formula, the theoretical combustion temperature involves important parameters such as air temperature, oxygen enrichment, air volume, coal ratio, and humidity. Therefore, the theoretical combustion temperature can be considered an important indicator for determining the thermal state of the furnace.

[0057] In a properly operating blast furnace, the theoretical combustion temperature typically maintains a stable fluctuation range. A too low theoretical combustion temperature indicates deteriorated heat exchange in the hearth and lower portion of the blast furnace, resulting in insufficient physical heat transfer between the slag and iron, which affects the reduction process and the quality of the pig iron. Furthermore, a too low theoretical combustion temperature reduces the combustion rate of pulverized coal, causing some unburned pulverized coal to settle in the hearth while others rise with the gas to block the coke window, impairing the permeability of the charge column. Excessively high theoretical combustion temperatures significantly accelerate the reaction between carbon, H2O, and O2 within the tuyere combustion zone, rapidly increasing gas volume in a short period of time and potentially causing flooding, pipework, and blast furnace operation difficulties. Furthermore, a too high theoretical combustion temperature can easily damage blowpipes and lances.

[0058] The relationship between the influence of oxygen-enriched coal injection on the theoretical combustion temperature is calculated by referring to Figure 3 As shown, according to Figure 3It can be calculated that the linear relationship between the theoretical combustion temperature (y) and the oxygen enrichment rate (x) is: y = 121x + 2013, and the linear relationship between the theoretical combustion temperature (y) and the coal ratio (x) is: y = 1.821x + 2624.

[0059] Depend on Figure 3 It can be seen that the theoretical combustion temperature increases with increasing oxygen enrichment and decreases with increasing coal ratio, and the linear correlation between coal ratio and theoretical combustion temperature is stronger than that of oxygen enrichment. Under current smelting conditions, considering the effects of oxygen enrichment and coal ratio on theoretical combustion temperature separately, calculations show that for every 1% increase in oxygen enrichment, the theoretical combustion temperature increases by approximately 55°C, while for every 10kg / t increase in coal ratio, the theoretical combustion temperature decreases by approximately 19°C. This infers that if the theoretical combustion temperature is maintained constant, a 1% increase in oxygen enrichment can increase the coal ratio by approximately 29kg / t. However, as shown in the formula, the coal ratio cannot be significantly increased due to the limited amount of gas in the large bosh furnace.

[0060] Increasing the oxygen enrichment rate can raise the theoretical combustion temperature. The increased oxygen content in the blast creates favorable conditions for carbon combustion and H2O reactions, accelerating the combustion process and rapidly increasing the amount of heat generated per unit time. Combined with the reduced amount of coal gas, the heat generated by combustion can heat the reaction products to a higher temperature. Increasing the coal ratio causes the theoretical combustion temperature to decrease, primarily due to the heat absorption from the decomposition of hydrocarbons in the pulverized coal and the increased amount of coal gas generated. Therefore, only a reasonable combination of oxygen enrichment and coal injection can achieve the best smelting conditions.

[0061] Therefore, the following conclusions are drawn:

[0062] (1) Oxygen enrichment and coal injection have significant complementary effects on the bosh gas volume, air resistance coefficient, and theoretical combustion temperature. In actual production, a reasonable combination of the two is a practical means to reduce smelting costs. Calculations show that for every 1% increase in oxygen enrichment, the coal ratio increases by approximately 12.5 kg / t.

[0063] (2) The bosh gas volume and air resistance coefficient play an important reference role in the prediction of blast furnace conditions. In daily production, the monitoring and control of these two parameters should be strengthened to maintain the above parameters within a reasonable range and maintain a smooth operation state.

[0064] Example 2: Sichuan Desheng Group Vanadium Titanium Co., Ltd., the applicant of the present invention, 3 From September to December 2024, the No. 3 blast furnace conducted practical exploration on increasing the oxygen enrichment and coal injection amount by referring to the rule of increasing the oxygen enrichment rate and coal ratio obtained in Example 1, that is, "for every 1% increase in oxygen enrichment rate, the coal ratio increases by 10-14kg / tFe".

[0065] Figure 4 This is a graph showing the trend of oxygen enrichment from September to December. Figure 4 It can be seen that during the period from September to December 2024, Desheng Vanadium Titanium Ironmaking Plant maintained the oxygen enrichment at 8000Nm in the early October. 3 / h, and then gradually increase the oxygen enrichment under the premise of ensuring the smooth operation of the furnace. In mid-November, the oxygen enrichment was increased to 12500Nm 3 / h level and maintain it. During this period, the furnace condition is stabilized and the hourly coal injection rate is also increased. Figure 5 shown.

[0066] like Figure 5 As shown in the figure, in the early stage of increasing the oxygen enrichment, the coal injection rate is about 22-23t / h. With the gradual increase of oxygen enrichment, the smelting intensity gradually increases, and the coal injection rate gradually increases to about 26t / h. At the same time, the coke ratio gradually decreases. Because the purchase price of coke is more expensive than coal powder, the smelting cost is on a downward trend with the increase of oxygen enrichment coal injection rate.

[0067] Figure 6 This is the trend chart of the batch weight of the mine. Figure 6 It can be seen that in the early October, the condition of the blast furnace showed a trend of deterioration, so the ore batch was reduced to about 33t. Subsequently, after a breakthrough in research, while increasing the amount of oxygen-enriched coal injection, the ore batch weight was increased according to the real-time changes in the furnace condition. After nearly two months of practice, the ore batch was finally increased to about 34.5t, and at the same time, the goal of smooth furnace condition was achieved.

[0068] Figure 7 The blast furnace output trend chart is as follows: Figure 7 It can be seen that during the September-December period, the blast furnace's performance remained under control, with production increasing from approximately 3,300 t / d before the practice to 3,750 t / d. This also confirms that increasing the amount of oxygen-enriched coal injection can improve blast furnace smelting intensity.

[0069] On November 13, 2024, due to the maintenance of No. 4 blast furnace, No. 3 blast furnace adopted reduced load production, from the normal coke load of 4.65 to 4.1, and the coal injection amount changed as follows: Figure 8 As shown, at normal load, the coal injection rate is about 31t / h. After the load is reduced, the coal injection rate drops to about 22t / h.

[0070] Two different coke loads were used, and two coal injection rates were adopted to stabilize the furnace conditions. When the furnace conditions were basically stable, two cost results were obtained: when the coke load was 4.65, the blast furnace adopted a coal injection rate of 31t / h, and the daily output was 4000t depending on the furnace conditions. Through calculation, the cost was 2988.89 yuan / tfe; when the coke load was 4.1, the blast furnace adopted a coal injection rate of 22t / h, and the daily output was 4000t depending on the furnace conditions. Through calculation, the cost was 3043.81 yuan / tfe. It can be seen that when high coal rates are injected, the coke load increases and the coke consumption decreases, which is conducive to reducing production costs.

[0071] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A blast furnace oxygen-enriched coal injection smelting method, characterized in that: The oxygen enrichment rate and coal ratio parameters in blast furnace smelting are adjusted according to the rule that for every 1% increase in oxygen enrichment rate, the coal ratio increases by 10-14kg / tFe.

2. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: The oxygen enrichment rate and coal ratio parameters in blast furnace smelting are adjusted according to the rule that for every 1% increase in oxygen enrichment rate, the coal ratio increases by 12.5kg / tFe.

3. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: The oxygen enrichment of the blast furnace is 12500Nm 3 / h, and the coal injection rate is 26t / h.

4. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: The coke load of blast furnace smelting is ≥4.

65.

5. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: Adopt oxygen-enriched operation mode with stable air volume.

6. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: A mixture of high-ash pulverized coal and low-ash pulverized coal is sprayed, wherein the ash content of the high-ash pulverized coal is ≥25%, and the ash content of the low-ash pulverized coal is ≤10%.

7. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: Control the blast furnace top pressure ≥65kpa.

8. The blast furnace oxygen-enriched coal injection smelting method according to claim 1, characterized in that: Blast furnace iron production ≥15 times / day.

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