Steelmaking process for slowing down burning loss of blast-furnace tuyere

Abstract

The invention belongs to the field of blast furnace smelting, and relates to a steelmaking process for slowing down burning loss of a blast-furnace tuyere. According to the technical scheme, the method comprises the steps that when the hearth accumulation phenomenon occurs in the smelting process, MgO, MnO2 and SiO2 are added into molten iron, the binary alkalinity of slag is kept to be 1.15-1.18, the magnesium-aluminum ratio of the slag is larger than or equal to 0.60-0.62, the quaternary alkalinity of the slag is kept to be 1.01-1.03, and omega [Mn] in the molten iron is kept to be 0.80%-1.00%. The temperature of the molten iron in the blast furnace hearth is kept at 1490-1515 DEG C; and the increment of the slag-iron ratio is controlled to be 5kg / t to 42kg / t.

Description

Technical Field

[0001] The invention belongs to the field of blast furnace smelting and relates to a steelmaking process for slowing down the burning loss of blast furnace tuyere. Background Art

[0002] During the blast furnace smelting process, accumulation occurs in the furnace due to reasons such as the quality of the cannon mud or the failure of the swing chute, resulting in frequent burning of the subsequent blast furnace tuyere, which in turn aggravates the accumulation in the furnace.

[0003] Generally, the furnace condition can be improved by strengthening management, improving raw material quality and using furnace cleaning agents. Generally, furnace cleaning agents can be cleaned with fluorite or acidic materials, mainly by controlling the alkalinity of slag to ensure the fluidity of slag. During the furnace cleaning period, the furnace temperature needs to be kept high to facilitate the melting of the deposits. Summary of the invention

[0004] In order to overcome the defects in the above-mentioned related technologies, the present invention proposes a steelmaking process for reducing the burning of blast furnace tuyere.

[0005] In order to achieve the above technical objectives, the present invention provides a steelmaking process for slowing down the burning of blast furnace tuyere, which is suitable for a furnace with a capacity of 1680m 3 The steelmaking process for slowing down the burning of blast furnace tuyere includes:

[0006] When the hearth accumulation phenomenon occurs during the smelting process, MgO, MnO2 and SiO2 are added to the molten iron to keep the binary basicity of the slag at 1.15-1.18, the magnesium-aluminum ratio of the slag is greater than or equal to 0.60-0.62, the quaternary basicity of the slag is kept at 1.01-1.03, and ω[Mn] in the molten iron is 0.80%-1.00%;

[0007] The temperature of molten iron in the blast furnace hearth is maintained at 1490℃~1515℃;

[0008] The increase in slag-iron ratio is controlled to be 5kg / t~42kg / t.

[0009] The method of adding MgO, MnO2 and SiO2 to the molten iron comprises: simultaneously adding manganese ore, serpentine and silica into a blast furnace.

[0010] The method for controlling the increase in the slag-iron ratio to 5kg / t to 42kg / t also includes increasing the coke ratio by 10kg / t to 60kg / t, that is, the coke ratio variation range is 390kg / t to 340kg / t, which is higher than the normal coke ratio of 330kg / t (10kg / t to 60kg / t), and its purpose is to improve the permeability of the material column.

[0011] The steelmaking process for slowing down the burning of blast furnace tuyere also includes:

[0012] When the blast furnace air pressure stably reaches 420 kPa and the slag-iron ratio increase is adjusted down to 24.0 kg / t, stop adding serpentine into the blast furnace;

[0013] When the increase in the slag-iron ratio is adjusted down to 16.0 kg / t, adding manganese ore into the blast furnace is stopped;

[0014] When the increase in slag-iron ratio decreases by 8.00 kg / t, adding silica into the blast furnace is stopped.

[0015] The beneficial effects of the present invention are:

[0016] The present invention can restore the blast furnace parameter indicators to normal levels and achieve the expected effect. The coal ratio is gradually, orderly and steadily increased from 120.0-130.0kg / t to 160.0kg / t, the air volume and wind speed are restored to normal levels, the coal gas utilization rate is improved, and the generation cost is reduced.

[0017] The daily output of the blast furnace recovered from 3697.89 tons / day to the normal 6450.00 tons / day; the center temperature of the furnace bottom rose to 284.4℃, reaching the normal level of 279.0℃, and the furnace hearth condition improved.

[0018] The present invention adopts serpentine, which is rich in silicon and magnesium, and controls the addition of silica to control the binary basicity of the slag and adjust the quaternary basicity of the slag. It can adjust the viscosity of the slag while performing desulfurization, increase the furnace temperature, and slow down the accumulation of the furnace.

[0019] The present invention adds manganese ore, and MnO2 in the manganese ore is easily reduced by CO and H2 indirectly. (1) MnO combines with SiO2 to form a low-melting-point MnSiO3 compound (1291°C) to improve slag fluidity; (2) the reaction of (MnO)+[C]=[Mn]+CO is beneficial to weakening the accumulation of graphite carbon in the furnace. The blast furnace adopts manganese ore to increase the molten iron ω[Mn] from 0.35-0.40% to 0.80-1.00%, thereby improving the furnace hot washing effect. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0023] Example 1

[0024] Take 1# blast furnace as an example.

[0025] The 1# blast furnace was shut down for replacement and water reduction maintenance of 19#, 23#, 24# tuyere small sets. The 4#, 7#, 25#, 26# tuyere small sets that had been online for a long time were replaced and full tuyere air supply was adopted.

[0026] In view of the continuous fluctuations in the furnace condition of No. 1 blast furnace and the trend of deterioration, the following measures are taken to improve the furnace condition:

[0027] First, optimization and adjustment of coke quality

[0028] The top-loading coke ratio was adjusted from 75% to 100.00%, all of which were dry-quenched coke. Subsequently, according to the coke inventory and furnace conditions, the reasonable adjustment and matching of the structure are as follows:

[0029] Table 1 Coke structure adjustment

[0030] time Adjustment of coke structure Day 1 10:00 Coke dry quenching 100.0%, top loading 100.0% (Gengyang 30.0% + Shanjiao quasi-first grade 20.0% + Meijin 50.0%) 14:00 on the first day Coke dry quenching 100.0%, top loading 100.0% (Gengyang 30.0% + Shanjiao quasi-first grade 20.0% + Meijin 50.0%) 2:00 p.m. the next day Coke dry quenching 100.0%, top loading 100.0% (Gengyang 30.0% + Meijin 50.0% + Linxin 20.0%) 22:00 the next day Coke dry quenching 100.0%, tamping 15.0% (Zhongxin 15.0%) + top loading 85.0% (Linxin 20.0% + Gengyang 30.0% + Meijin 35.0%)

[0031] Table 2 Comparison of coke composition Unit: %

[0032]

[0033] At 10:00 on the first day, the blast furnace was restored, the coke ratio of the blast furnace was increased to 390kg / t, and the coal ratio was adjusted to 100-110kg / t; as the furnace condition improved, the blast furnace increased the coal ratio and reduced the coke ratio in an orderly manner, as follows:

[0034] (1) At 1:00 on the second day, the blast furnace coke ratio was gradually adjusted to 370kg / t, and the coal ratio was increased to 120-130kg / t; at 7:00, the blast furnace coke ratio was gradually adjusted to 365kg / t, and the coal ratio was increased to 130-135kg / t; at 11:00, the blast furnace coke ratio was gradually adjusted to 360kg / t, and the coal ratio was increased to 135-140kg / t; at 14:00, the blast furnace coke ratio was gradually adjusted to 355kg / t, and the coal ratio was increased to 140-145kg / t;

[0035] (2) On the third day at 1:00 am, the blast furnace coke ratio was gradually adjusted to 350 kg / t, and the coal ratio was increased to 145-150 kg / t; at 7:00 am, the blast furnace coke ratio was gradually adjusted to 340 kg / t, and the coal ratio was increased to 150-155 kg / t;

[0036] (3) At 1:00 am on the fourth day, the blast furnace coke ratio was gradually adjusted to 330 kg / t, and the coal ratio was increased to 160-165 kg / t. It remained stable and no adjustment was made for the time being.

[0037] Second, mine batch adjustment

[0038] The material rate is 5.5-6.0 batches / hour, and the ore batch size is selected as follows:

[0039] At 10:00 on the first day, the blast furnace was resumed and the blast furnace ore batch was reduced to 50.0 tons; the furnace condition recovered smoothly, the air volume increased, and the material speed became faster, and the ore batch was increased to 55.0 tons at 22:00; it was increased to 60 tons at 1:00 on the second day; and it was increased to 62.0 tons at 0:00 on the third day, and it remained stable and no adjustment was made for the time being.

[0040] Third, fabric matrix optimization and adjustment

[0041] While the material speed is matched with the ore batch, the material distribution matrix is ​​adjusted accordingly. The main idea is to first guide the central airflow and then dredge it, and adjust it to the "platform + funnel + center coke" material distribution mode to improve the central airflow, take care of the edges, and stabilize the two airflows. The translation adjustment of the distribution matrix platform is based on the principle of 0.5 meter loss per material line and 1° contraction of the coke and ore platform. The normal material line is 1.5 meters:

[0042]

[0043] Fourth, the theoretical combustion temperature should be reasonably controlled

[0044] Table 3: According to the reasonable combination of wind temperature, coal ratio and oxygen enrichment rate, the theoretical combustion temperature can be stabilized as follows:

[0045]

[0046] Through the above adjustments, the blast furnace air temperature gradually recovered to above 1200℃, the coal ratio reached 160kg / t, and the theoretical combustion temperature was maintained at 2400-2430℃; the furnace temperature gradually stabilized from 0.70-0.90% to 0.40-0.60%, the physical heat of molten iron averaged 1515℃, the highest was 1530℃, the lowest was 1490℃, and the furnace heat was sufficient; the blast furnace air volume returned to normal above 3700m3 / min, the wind speed gradually reached above 240m / s, and the furnace was active.

[0047] Fifth, add solvent, optimize and adjust the slag system, strengthen the hot washing of blast furnace and adjust the furnace state

[0048] Combined with the above-mentioned first and second improvement measures, the iron tapping in front of the furnace is stable, the permeability of the material column is improved, the heat of the furnace is sufficient (gradually stabilized from 0.70-0.90% to 0.40-0.60%, the average physical heat of molten iron is 1515℃, the highest is 1530℃, and the lowest is 1490℃), the wind speed is stable, and the blast furnace simultaneously adopts different degrees of adding manganese ore, serpentine, silica and other solvents, and appropriately increases the specific heat of slag and iron for washing, and strengthens the improvement of the furnace. The situation is as follows:

[0049] Table 4: Manganese ore, serpentine and silica added with the ore batch

[0050]

[0051] Through the above adjustments, the furnace state continues to improve, and the slag adjustment changes are as follows:

[0052] (1) Changes in slag magnesium-aluminum ratio

[0053] On the first day, 400-500kg / batch of serpentine was added to the blast furnace. The ω(MgO) in the slag increased from 9.50% to 10.50%, and reached a maximum of 11.20% on the second day. The binary basicity of the slag was reduced from 1.20-1.22 to 1.15-1.16, and the magnesium-aluminum ratio was increased from 0.58-0.59 to 0.70-0.72, reaching a maximum of 0.74-0.75. The quaternary basicity of the slag was maintained at 1.01-1.03.

[0054] By 0:00 on the third day, the blast furnace wind pressure stabilized at 420kpa, the furnace condition was smooth, and the specified full wind state was reached. The sintering ingredient structure: increased dolomite ratio, ω (MgO) in the sintered ore was adjusted from 2.20% to 2.31%, reduced high aluminum material ratio, ω (Al2O3) in the sintered ore was reduced from 2.20% to 2.10%, and the pellet inventory was tight. At 5:50, serpentine was stopped, and the blast furnace resumed 5.0% lump ore ratio, ω (MgO) in the slag gradually recovered to 9.20%, the binary basicity of blast furnace slag gradually increased to 1.18-1.19, the magnesium-aluminum ratio was maintained at 0.60-0.62, and the quaternary basicity of the slag continued to remain at 1.00-1.02, meeting the expected requirements.

[0055] (2) Changes in [Mn] in molten iron

[0056] On the first day, 800-900kg / batch of manganese ore was added to the blast furnace. The ω[Mn] in the molten iron gradually increased from 0.35-0.40% to 0.80-0.90%. On the second day, it reached a maximum of 1.01-1.03%. At 10:00 on the third day, the blast furnace wind pressure stabilized at 435kpa, the furnace condition went smoothly, the blast furnace wind pressure returned to normal levels, the furnace hearth condition improved significantly, and the center temperature of the furnace bottom at 6.394 meters rose to 284.4℃, reaching the normal level of 279.0℃, meeting the expected requirements. At 18:00, manganese ore was discontinued, and [Mn] in the molten iron gradually returned to the normal level of 0.35-0.40%.

[0057] (3) Changes in slag-iron ratio adjustment

[0058] On the second day from 7:50 to 10:00, the blast furnace was shut down and the tuyere was replaced and the air was restored, the dosage of manganese ore, serpentine and silica was increased to enhance the effect of hot washing the furnace hearth. The increase in slag-iron ratio increased from 28-29kg / t to 41.73kg / t, the air supply furnace condition was restored smoothly, the blast furnace wind pressure stabilized at 420kpa, and the increase in slag-iron ratio was reduced to about 24.0kg / t at 22:00; on the third day at 5:50, serpentine was stopped, and the increase in slag-iron ratio was reduced to about 16.0kg / t; at 18:00, manganese ore was stopped, and the increase in slag-iron ratio was reduced to about 8.00kg / t; as the condition of the blast furnace hearth improved, the smelting strength continued to increase in an orderly manner, and the coal ratio was gradually increased to 140-145kg / t on the fourth day. In order to continuously improve the air permeability of the lower material column, silica in the blast furnace was stopped at 10:00.

[0059] Table 5: Comparison of solvent composition used in blast furnaces Unit: %

[0060] name Tf <![CDATA[Si02]]> Ca0 MgO <![CDATA[A1203]]> Mn Manganese Ore 23.05 5.85 0.35 0.30 10.00 29.25 Serpentine - 37.52 0.03 40.83 0.30 - Silica - 96.72 0.26 0.36 0.98 -

[0061] After the 1# blast furnace adopted the above measures, the furnace condition recovered smoothly after the wind was stopped and the tuyere was replaced on the second day. By 0:00 on the third day, the wind pressure of the blast furnace had stabilized to 420kpa, reaching the required full wind state. The parameters and indicators were optimized and adjusted in an orderly manner, and the furnace condition continued to be stable and smooth. From the second day to the seventh day, the furnace condition was stabilized and improved significantly, and the improvement of parameters and indicators reached the expected effect, as follows:

[0062] 1. Zero slow wind rate and zero air outlet damage

[0063] From the second day to the seventh day, the furnace condition was stable. There was no hanging material or reduced wind. The slow wind rate of the blast furnace was 0%. The blast furnace air volume recovered to 3750m3 / min, the wind speed reached 245m / s, and the tuyere was not damaged.

[0064] 2. Increased coal ratio

[0065] The coal ratio is gradually and orderly increased from 120-130kg / t to 160.0kg / t, an increase of about 30.0kg / t, and the cost is reduced by 30.0*1.0=30.0 yuan / t (the price difference of coal and coke is 1,000 yuan / t).

[0066] 3. The furnace condition is stable and the gas utilization rate is steadily improved.

[0067] The gas utilization increased from 43.86% to 46.56%, and the gas utilization increased by 2.70% relatively. Its benefits (coke unit price 2100 yuan / t; gas utilization increased by 1%, coke ratio reduced by 5kg / t) are:

[0068] Reduce the coke ratio: 5*2.7=13.50kg / t; (2) Reduce the molten iron cost by 13.50*2.1=28.35 yuan / t.

[0069] 4. Increased blast furnace output

[0070] Blast furnace output recovered from 3,697.89 tons / day to normal 6,450 tons / day.

[0071] Other improvements: The center temperature of the furnace bottom rose to 284.4℃, reaching the normal level of 279.0℃.

[0072] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0073] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A steelmaking process for slowing down the burning of blast furnace tuyere, suitable for furnaces with a capacity of 1680m 3 A blast furnace, characterized in that The steelmaking process for slowing down the burning of blast furnace tuyere comprises: When the hearth accumulation phenomenon occurs during the smelting process, MgO, MnO2 and SiO2 are added to the molten iron to keep the binary basicity of the slag at 1.15-1.18, the magnesium-aluminum ratio of the slag is greater than or equal to 0.60-0.62, the quaternary basicity of the slag is kept at 1.01-1.03, and ω[Mn] in the molten iron is 0.80%-1.00%; The temperature of molten iron in the blast furnace is maintained at 1490℃~1515℃; The increase in slag-iron ratio is controlled to be 5kg / t~42kg / t.

2. The steelmaking process for mitigating blast furnace tuyere burning loss according to claim 1, characterized in that: The method of adding MgO, MnO2 and SiO2 to the molten iron comprises: Manganese ore, serpentine and silica are added simultaneously to the blast furnace.

3. The steelmaking process for mitigating blast furnace tuyere burning loss according to claim 2, characterized in that: The method for controlling the increase in the slag-iron ratio to be 5kg / t to 42kg / t also includes increasing the coke ratio by 10kg / t to 60kg / t.

4. The steelmaking process for mitigating blast furnace tuyere burning loss according to claim 3, characterized in that: The steelmaking process for slowing down the burning of blast furnace tuyere also includes: When the blast furnace air pressure stably reaches 420 kPa and the slag-iron ratio increase is adjusted down to 24.0 kg / t, stop adding serpentine into the blast furnace; When the increase in the slag-iron ratio is adjusted down to 16.0 kg / t, adding manganese ore into the blast furnace is stopped; When the increase in slag-iron ratio decreases by 8.00 kg / t, adding silica into the blast furnace is stopped.

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