In-furnace high-ventilation efficient sintering process

Abstract

The invention relates to the technical field of sintering, and discloses an in-furnace high-permeability efficient sintering process which comprises the following steps: step 1, selecting raw ore; step 2, proportioning raw ore; 3, high-quality lime application; step 4, steam preheating; step 5, sintering process control; and 6, sintering is completed. In the first step, the proportion of small-particle-size raw ore in the proportion is increased to 20%, the compactness and uniformity of a sintered block are improved, combination is easier during sintering, and therefore the strength and stability of a final product are improved, in the second step, the average particle size is controlled to be 5 mm, the particle size smaller than 1 mm is smaller than 5%, and the particle size larger than 3 mm is larger than 65%. The method ensures good fluidity and effective reaction of the material in the sintering process, the moisture content is controlled to 6.8-8%, pulverization is reduced, the strength and stability of the sintered ore are improved, and the beneficial effects of improving the drum strength and metallurgical performance of the sintered ore and ensuring long-period stable and smooth operation of the blast furnace condition are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sintering, in particular to a high-permeability and high-efficiency sintering process in a furnace. Background Art

[0002] At present, there are many types of imported and domestic ores, and there are great differences in quality and price. Under this circumstance, the rational use of iron ore resources to meet the needs of the steel industry to reduce costs and increase efficiency is one of the key research focuses of various steel companies.

[0003] Through the practice and technical research of high-permeability and high-efficiency sintering process in the furnace, we can reasonably and economically determine the sintering ore and ingredient structure, and find the best ratio range as much as possible, which has a wide range of practical significance for our company. The iron raw materials of steel enterprises come from a variety of channels, and they have their own differences. The high and low grades of iron ore powders from various sources, the amount of harmful impurities, and the differences in slag composition are all objective. Summary of the invention

[0004] Technical issues solved:

[0005] In view of the deficiencies in the prior art, the present invention provides a highly breathable and efficient sintering process in a furnace, which has the advantages of improving the drum strength and metallurgical properties of the sintered ore, ensuring the long-term stable operation of the blast furnace condition; eliminating some of the cost increases caused by the decrease in sintered ore grade, the increase in ore unit consumption caused by high silicon and high aluminum, and the increase in coke ratio, thereby solving the problems of the above-mentioned technologies.

[0006] Technical solution:

[0007] To achieve the above object, the present invention provides the following technical solution: a high-permeability and high-efficiency sintering process in a furnace, comprising the following steps:

[0008] Step 1: Selection of raw ore: Increase the proportion of small-sized raw ore in the mix to 20%;

[0009] Step 2: Raw ore proportion: monitor the particle size distribution of the mixture, control the average particle size at 5mm, the content of particles below 1mm is less than 5%, and the content of particles above 3mm is greater than 65%;

[0010] Step 3: Application of high-quality lime: Replace low-quality lime with high-quality lime, maintaining R = 1.92;

[0011] Step 4: Steam preheating: Send the materials with selected proportions into a primary mixer, introduce steam into the water inlet pipe of the primary mixer, configure multiple steam inlets, and the temperature of the mixture reaches above 60°C;

[0012] Step 5: Sintering process control: stabilize the main exhaust door opening, control the air volume in the ignition section, keep the ignition negative pressure within the range of 6000-8000PA, and promote uniform gas flow;

[0013] Step 6: Sintering is completed: After sintering is completed, the air doors of the ring cooler are opened in a "step-by-step" manner to control the cooling speed and avoid the rapid cooling and pulverization of the sintered ore.

[0014] Preferably, in the step 4, a mixed water inlet pipe plus steam technology is used, steam is introduced into a mixed water inlet pipe, and multiple steam inlets are set on the water inlet pipe to mix the water flow and the steam in the water inlet pipe, ensuring that the steam can be evenly distributed in the pipeline and the steam and the water flow are evenly mixed, and the number of steam inlets is at least two.

[0015] Preferably, the primary mixer is installed at an inclination angle of 2.5° and a mixing time of 2.35 min, and the filling rate is controlled at 12.7%-15.09%, which is conducive to controlling the moisture content of the material at 6.8%-8%. At the same time, a steam heating device is used to control the water temperature at 80°C.

[0016] Preferably, the average particle size in step 2 is calculated as:

[0017]

[0018] Where: MPS is the average particle size; w i is the percentage content of the i-th particle size interval; d i is the average particle size of the ith particle size interval.

[0019] Preferably, the content of particles with a diameter of less than 1 mm in step 2 is calculated as:

[0020]

[0021] The particle size distribution data are: 0-0.5mm-2.5%; 0.5-1mm-1.5%; 1-2mm-15%; 2-3mm-25%; 3-4mm-20%; 4-5mm-15%; 5-6mm-10%; 6-7mm-5%; 7-8mm-2.5%; 8-9mm-2%; 9-10mm-1.5%;

[0022] Where: w 1 It is the percentage content of each interval with particle size less than 1mm.

[0023] Preferably, in step 2

[0024]

[0025] Where: w 3It is the percentage content of each interval with a particle size greater than or equal to 3mm.

[0026] Preferably, the effectiveness of lime in step 3 is calculated as:

[0027]

[0028] Where: C eff C is the content of effective calcium oxide (CaO) in lime; total is the total calcium oxide CaO content; R is the effectiveness ratio of lime;

[0029] In order to maintain R = 1.92, when replacing inferior lime with high-quality lime, ensure that the ratio of the effective calcium oxide content to the total calcium oxide content of the new lime meets the following conditions:

[0030] Preferably, the steam preheating calculation in step 4 is:

[0031] Q steam =m steam ·(h steam -h cond )

[0032] Where: m steam is the total energy transferred by steam J; h steam is the enthalpy of steam J / kg; Q steam is the total energy transferred by steam; h cond is the enthalpy of condensed water.

[0033] Preferably, the temperature rise of the mixture in step 4 is calculated by energy balance:

[0034] Q steam =m mix ·c mix ·(T final -T initial )

[0035] Where: m mix is the mass of the mixture; c mix is the specific heat capacity; T initial is the initial temperature; T initial is the final temperature; Q steam is the total energy transferred by the steam.

[0036] Preferably, in step 5, the flow is regulated by the damper area and calculated as:

[0037] P target =P ambient -ΔP

[0038] Where: P targetis the target negative pressure Pa, between 6000 and 8000 Pa; ΔP is the pressure difference in the ignition section (Pa), i.e. the required negative pressure; P ambient is the ambient air pressure;

[0039] Set the flow coefficient and gas density: C d =0.95;

[0040] Set pressure difference: Select 6500Pa as the target ΔP;

[0041] Assume the effective cross-sectional area of ​​the damper is A = 0.01m 2 , then the gas flow rate is:

[0042]

[0043] Perform the calculation:

[0044] Compared with the prior art, the present invention provides a high-permeability and high-efficiency sintering process in a furnace, which has the following beneficial effects:

[0045] 1. The present invention improves the compactness and uniformity of the sintered block by increasing the proportion of small-size ore in the mix to 20% in step one, making it easier to combine during sintering, thereby improving the strength and stability of the final product. The particle size distribution in step two controls the average particle size to be 5 mm, the particle size below 1 mm is less than 5%, and the particle size above 3 mm is greater than 65%, thereby ensuring good fluidity and effective reaction of the material during the sintering process. The reasonable distribution of particle size not only enhances the strength of the sintered ore, but also improves the air permeability, thereby improving the metallurgical properties. Replacing inferior lime with high-quality lime to maintain R=1.92 ensures the content of effective calcium oxide in the lime, increases the effectiveness of the reaction and the strength of the product, and increases the temperature of the mixture to above 60°C through the steam preheating technology in step four, so that the chemical reaction between the materials is more sufficient, providing better conditions for the subsequent sintering process. The moisture content is controlled at 6.8%-8% to reduce pulverization, improve the strength and stability of the sintered ore, and achieve the beneficial effects of improving the drum strength and metallurgical properties of the sintered ore and ensuring the long-term stable and smooth operation of the blast furnace condition.

[0046] 2. The present invention improves the reaction efficiency of lime at high temperature and enhances the reactivity of sintered ore in a blast furnace by replacing inferior lime with high-quality lime and ensuring the effective calcium oxide content ratio R=1.92. The reasonable particle size distribution: the average particle size is controlled to be 5 mm, and the particle size above 3 mm is greater than 65%, thereby improving the air permeability and sintering effect of the pile, ensuring a more complete reaction, and increasing the proportion of small-size ore in the proportion to 20%, further improving the uniformity and strength of the sintered ore, thereby reducing the unit consumption of ore. By introducing steam into the mixture to increase its temperature, the reactivity of the raw materials is improved, and at the same time, the optimal moisture content of the material is ensured to be 6.8%-8%. This not only reduces the pulverization phenomenon of the material during the sintering process, but also effectively controls the coke ratio and reduces the overall production cost, thereby achieving the beneficial effect of eliminating part of the cost increase problems caused by the decrease in the taste of the sintered ore, the increase in the unit consumption of the ore caused by the high silicon and high aluminum, and the increase in the coke ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the steps of the present invention; DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] See also Figure 1 , a high-permeability and high-efficiency sintering process in a furnace, comprising the following steps:

[0050] Step 1: Selection of raw ore: Increase the proportion of small-sized raw ore in the mix to 20%;

[0051] Step 2: Raw ore proportion: monitor the particle size distribution of the mixture, control the average particle size at 5mm, the content of particles below 1mm is less than 5%, and the content of particles above 3mm is greater than 65%;

[0052] Step 3: Application of high-quality lime: Replace low-quality lime with high-quality lime, maintaining R = 1.92;

[0053] Step 4: Steam preheating: Send the materials with selected proportions into a primary mixer, introduce steam into the water inlet pipe of the primary mixer, configure multiple steam inlets, and the temperature of the mixture reaches above 60°C;

[0054] Step 5: Sintering process control: stabilize the main exhaust door opening, control the air volume in the ignition section, maintain the ignition negative pressure within the range of 6000-8000PA, and promote uniform gas flow;

[0055] Step 6: Sintering is completed: After sintering is completed, the air doors of the ring cooler are opened in a "step-by-step" manner to control the cooling speed and avoid the rapid cooling and pulverization of the sintered ore.

[0056] Specifically, in step 4, a mixed water inlet pipe plus steam technology is used, steam is introduced into a mixed water inlet pipe, and multiple steam inlets are set on the water inlet pipe to mix the water flow and steam in the water inlet pipe, ensuring that the steam can be evenly distributed in the pipeline, so that the steam and water flow are evenly mixed, and there are at least two steam inlets.

[0057] By increasing the proportion of small-sized ore in the mix to 20% in step 1, the density and uniformity of the sintered block are improved, making it easier to combine during sintering, thereby improving the strength and stability of the final product. The particle size distribution in step 2 controls the average particle size to be 5mm, the particle size below 1mm is less than 5%, and the particle size above 3mm is greater than 65%, ensuring good fluidity and effective reaction of the material during the sintering process. Reasonable particle size distribution not only enhances the strength of the sintered ore, but also improves the permeability, thereby improving the metallurgical properties.

[0058] Replacing low-quality lime with high-quality lime to maintain R = 1.92 ensures the content of effective calcium oxide in the lime, increasing the effectiveness of the reaction and the strength of the product.

[0059] High-quality lime can better participate in the melting process and improve the quality of the sintered ore. The steam preheating technology in step 4 increases the temperature of the mixture to above 60°C, making the chemical reaction between the materials more complete and providing better conditions for the subsequent sintering process. The moisture content is controlled at 6.8%-8% to reduce pulverization and improve the strength and stability of the sintered ore.

[0060] Specifically, the installation angle of the primary mixer is designed to be 2.5°, the mixing time is 2.35 minutes, and the filling rate is controlled at 12.7%-15.09%, which is conducive to controlling the moisture content of the material at 6.8%-8%. At the same time, the steam heating device is used to control the water temperature at 80°C.

[0061] Specifically, the average particle size in step 2 is calculated as:

[0062]

[0063] Where: MPS is the average particle size; w i is the percentage content of the i-th particle size interval; d i is the average particle size of the ith particle size interval.

[0064] Specifically, the content of particles with a diameter of less than 1 mm in step 2 is calculated as follows:

[0065]

[0066] The particle size distribution data is: 0-0.5mm-2.5%; 0.5-1mm-1.5%; 1-2mm-15%; 2-3mm-25%; 3-4mm-20%; 4-5mm-15%; 5-6mm-10%; 6-7mm-5%; 7-8mm-2.5%; 8-9mm-2%; 9-10mm-1.5%;

[0067] Where: w 1 It is the percentage content of each interval with particle size less than 1mm.

[0068] Specifically, in step 2

[0069]

[0070] Where: w 3 It is the percentage content of each interval with a particle size greater than or equal to 3mm.

[0071] Specifically, the effectiveness of lime in step 3 is calculated as:

[0072]

[0073] Where: C eff C is the content of effective calcium oxide (CaO) in lime; total is the total calcium oxide CaO content; R is the effectiveness ratio of lime;

[0074] In order to maintain R = 1.92, when replacing inferior lime with high-quality lime, ensure that the ratio of the effective calcium oxide content to the total calcium oxide content of the new lime meets the following conditions:

[0075] Specifically, the steam preheating calculation in step 4 is:

[0076] Q steam =m steam ·(h steam -h cond )

[0077] Where: m steam is the total energy transferred by steam J; h steam is the enthalpy of steam J / kg; Q steam is the total energy transferred by steam; h cond is the enthalpy of condensed water.

[0078] Specifically, the temperature rise of the mixture in step 4 is calculated by energy balance:

[0079] Q steam =m mix ·c mix·(T final -T initial )

[0080] Where: m mix is the mass of the mixture; c mix is the specific heat capacity; T initial is the initial temperature; T initial is the final temperature; Q steam is the total energy transferred by the steam.

[0081] Specifically, in step 5, the flow is adjusted by the damper area and calculated as:

[0082] P target =P ambient -ΔP

[0083] Where: P target is the target negative pressure Pa, between 6000 and 8000 Pa; ΔP is the pressure difference in the ignition section (Pa), i.e. the required negative pressure; P ambient is the ambient air pressure;

[0084] Set the flow coefficient and gas density: C d =0.95;

[0085] Set pressure difference: Select 6500Pa as the target ΔP;

[0086] Assume the effective cross-sectional area of ​​the damper is A = 0.01m 2 , then the gas flow rate is:

[0087]

[0088] Perform the calculation:

[0089] By replacing inferior lime with high-quality lime and ensuring the effective calcium oxide content ratio R=1.92, the reaction efficiency of lime at high temperature is improved, and the reactivity of sintered ore in the blast furnace is enhanced. Through reasonable particle size distribution: the average particle size is controlled to be 5mm, and the particle size above 3mm is greater than 65%, the permeability of the pile and the sintering effect are improved, ensuring a more complete reaction, and increasing the proportion of small-size ore in the mix to 20%, the uniformity and strength of the sintered ore are further improved, thereby reducing the unit consumption of ore. By introducing steam into the mixture to increase its temperature, the reactivity of the raw materials is improved, and at the same time, the optimal moisture content of the material is ensured to be 6.8%-8%. This not only reduces the pulverization of the material during the sintering process, but also effectively controls the coke ratio and reduces the overall production cost.

[0090] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-permeability and high-efficiency sintering process in a furnace, characterized in that: The following steps are involved: Step 1: Selection of raw ore: Increase the proportion of small-sized raw ore in the mix to 20%; Step 2: Raw ore proportion: monitor the particle size distribution of the mixture, control the average particle size at 5mm, the content of particles below 1mm is less than 5%, and the content of particles above 3mm is greater than 65%; Step 3: Application of high-quality lime: Replace low-quality lime with high-quality lime, maintaining R = 1.92; Step 4: Steam preheating: Send the materials with selected proportions into a primary mixer, introduce steam into the water inlet pipe of the primary mixer, configure multiple steam inlets, and the temperature of the mixture reaches above 60°C; Step 5: Sintering process control: stabilize the main exhaust door opening, control the air volume in the ignition section, maintain the ignition negative pressure within the range of 6000-8000PA, and promote uniform gas flow; Step 6: Sintering is completed: After sintering is completed, the air doors of the ring cooler are opened in a "step-by-step" manner to control the cooling speed and avoid the rapid cooling and pulverization of the sintered ore.

2. The high-permeability and high-efficiency sintering process in a furnace according to claim 1, characterized in that: In the step 4, a mixed water inlet pipe adding steam technology is used, steam is introduced into a mixed water inlet pipe, and multiple steam inlets are set on the water inlet pipe to mix the water flow and steam in the water inlet pipe, ensuring that the steam can be evenly distributed in the pipeline, so that the steam and water flow are evenly mixed, and the number of steam inlets is at least two.

3. The high-permeability and high-efficiency sintering process in a furnace according to claim 1, characterized in that: The primary mixer is designed to be installed at an inclination angle of 2.5° and a mixing time of 2.35 min, which controls the filling rate at 12.7%-15.09%, and is conducive to controlling the moisture content of the material at 6.8%-8%. At the same time, the steam heating device is used to control the water temperature at 80°C.

4. The high-permeability and high-efficiency sintering process in a furnace according to claim 1, characterized in that: The average particle size in step 2 is calculated as: Where: MPS is the average particle size; w i is the percentage content of the i-th particle size interval; d i is the average particle size of the ith particle size interval.

5. The high-permeability and high-efficiency sintering process in a furnace according to claim 4, characterized in that: The content of particles with a diameter of less than 1 mm in step 2 is calculated as follows: The particle size distribution data are: 0-0.5mm-2.5%; 0.5-1mm-1.5%; 1-2mm-15%; 2-3mm-25%; 3-4mm-20%; 4-5mm-15%; 5-6mm-10%; 6-7mm-5%; 7-8mm-2.5%; 8-9mm-2%; 9-10mm-1.5%; Where: w1 is the percentage content of each interval with a particle size less than 1 mm.

6. A high-permeability and high-efficiency sintering process in a furnace according to claim 5, characterized in that: In step 2 Wherein: w3 is the percentage content of each interval with a particle size greater than or equal to 3 mm.

7. The high-permeability and high-efficiency sintering process in a furnace according to claim 6, characterized in that: The effectiveness of the lime in step 3 is calculated as: Where: C eff C is the content of effective calcium oxide (CaO) in lime; total is the total calcium oxide CaO content; R is the effectiveness ratio of lime; In order to maintain R = 1.92, when replacing inferior lime with high-quality lime, ensure that the ratio of the effective calcium oxide content to the total calcium oxide content of the new lime meets the following conditions:

8. The high-permeability and high-efficiency sintering process in a furnace according to claim 7, characterized in that: The steam preheating calculation in step 4 is: Q steam =m steam ·(h steam -h cond ) Where: m steam is the total energy transferred by steam J; h steam is the enthalpy of steam J / kg; Q steam is the total energy transferred by steam; h cond is the enthalpy of condensed water.

9. The high-permeability and high-efficiency sintering process in a furnace according to claim 8, characterized in that: The temperature rise of the mixture in step 4 is calculated by energy balance: Q steam =m mix ·C mix ·(T final -T initial ) Where: m mix is the mass of the mixture; c mix is the specific heat capacity; T initial is the initial temperature; T initial is the final temperature; Q steam is the total energy transferred by the steam.

10. The high-permeability and high-efficiency sintering process in a furnace according to claim 9, characterized in that: In step 5, the flow is regulated by the damper area and calculated as: P target =P ambient -ΔP Where: P target is the target negative pressure Pa, between 6000 and 8000 Pa; ΔP is the pressure difference in the ignition section (Pa), i.e. the required negative pressure; P ambient is the ambient air pressure; Set the flow coefficient and gas density: C d =0.95; Set pressure difference: Select 6500Pa as the target ΔP; Assume the effective cross-sectional area of ​​the damper is A = 0.01m 2 , then the gas flow rate is: Perform the calculation:

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