A low-cost coke feeding method and device for large blast furnaces

Abstract

The present invention discloses a method for charging coke in a low-cost large blast furnace, belonging to the field of blast furnace production, which includes coke grading and separation, top-of-furnace parallel bin sequential burden distribution, and control of the central coke charging amount. Among them: the coke grading and separation is to divide the coke into high-price high-quality coke and low-price secondary coke, and store them in separate bins under the bunker; the top-of-furnace parallel bin sequential burden distribution is to distribute the burden in the order of "main coke → central coke → ore → central coke → ore"; the control of the central coke charging amount is to control the central coke charging amount to be less than 5% of the coke batch weight. Compared with the prior art, it has the characteristics of cost reduction and efficiency increase.

Description

Technical Field

[0001] The present invention relates to an iron-making device and a charging operation method for a blast furnace, in particular to a method and device for charging coke into a large blast furnace at low cost. Background Art

[0002] Coke is the main raw material for blast furnace ironmaking. Coke burns in the tuyere area to generate carbon dioxide and release heat. These heats are almost all the heat sources for ore reduction and melting in the blast furnace. At the same time, coke also plays the roles of a reducing agent and a skeleton support, and the carbon in coke can also make the carbon content of pig iron reach about 4%. However, in the prior art, due to the size of the hearth of large blast furnaces, especially the large hearth diameter, the hearth activity is low. Industrial production has to be forced to consume a high proportion of high-price high-quality coke to ensure the hearth activity, the proportion of low-price secondary coke is low, and the molten iron cost remains high.

[0003] Therefore, in the "Method for Matching Coke into the Furnace during the Blast Furnace Smelting Process" (CN201610456027.0), according to the smelting requirements, coke is matched and added to the blast furnace in the order of the index from high to low; the indexes from high to low are: CSR > M > average particle size > M > ash content > CRI > sulfur content. However, this method only feeds materials by component matching, the proportion of high-price high-quality coke is high, the proportion of low-price secondary coke is low, and the molten iron cost is high.

[0004] The "Blasting Method of Coke for a Blast Furnace" (CN202210850763.X) considers from the perspective of the skeleton channel and ensures the smooth production of the blast furnace by improving the coke blasting method. The method includes: a. screening the coke particle size; b. preparing a passivator; step c. performing passivation treatment according to the particle size respectively; d. placing passivated materials of different levels into different intermediate charging bins; e. feeding materials using a batcher. The particle size classification of this method has six levels, and the passivation procedure and the storage and charging methods are complex, which are divorced from the actual production.

[0005] In addition, in actual work, the non-mining area in the center is large, the gas utilization rate is low, the fuel consumption is high, and the central gas flow is thick and weak, and the furnace condition's ability to resist fluctuations is poor. To ensure the central gas flow, when the large blast furnace is designed as a parallel hopper, the central coke addition ratio of the large blast furnace reaches more than 20%. When the large blast furnace is designed as a series hopper, although it is beneficial to the central gas flow, the central coke addition amount ratio is even more uncontrollable, and only the central coke addition position and the central coke addition amount can be calculated based on the ring position and the number of circles. In addition, the prior art also has defects such as unstable central coke addition amount, the central coke addition occupying the main ore and main coke charging process, lacking an independent charging system, being prone to material shortage in the charging line, and non-concentrated central coke charging. Summary of the Invention

[0006] The technical task of the present invention is to provide a low-cost coke feeding method and device for large blast furnaces in view of the above deficiencies of the prior art. The device of the present invention stores in separate bins under the silo, measures separately, and the pipe belt conveyor feeds independently. The top-of-furnace parallel bin sequential charging mode is center coke addition, realizing accurate measurement and independent feeding, creating conditions for accurate burden distribution. In the process of the present invention, through the coke grading and separation technology, a suitable proportion of high-quality center coke, reducing the proportion of high-price high-quality coke in large blast furnaces and increasing the proportion of low-price secondary coke, while ensuring the stable and smooth operation of the blast furnace, the molten iron cost is greatly reduced.

[0007] The technical solution for the present invention to solve its technical problems is: a low-cost coke feeding method for large blast furnaces, characterized in that: it includes coke grading and separation, top-of-furnace parallel bin sequential charging, and center coke addition amount control, wherein: the coke grading and separation is: dividing coke into high-price high-quality coke and low-price secondary coke, and storing in separate bins under the silo;

[0008] The top-of-furnace parallel bin sequential charging is: charging in the order of "main coke → center coke → ore → center coke → ore"; the center coke addition amount control is: controlling the center coke addition amount to be less than 5% of the coke batch weight.

[0009] Further, the above-mentioned high-price high-quality coke is top-charged first-class dry quenched coke, and other coke is defined as low-price secondary coke.

[0010] Further, the above-mentioned top-of-furnace parallel bin has three charging bins, the two sides are the first main bin and the second main bin, and the middle is the center coke bin. The discharge port of the center coke bin is between the discharge ports of the first main bin and the second main bin.

[0011] Further, the first main bin and the second main bin take turns receiving and discharging main coke and main ore.

[0012] Further, the above-mentioned three charging bins are arranged in an isosceles triangle.

[0013] Further, no charging line is released when distributing center coke.

[0014] Further, in the above-mentioned sequential charging, the addition amount of primary ore ≥ the addition amount of secondary ore, and the addition amount of secondary ore is not less than the critical ore batch weight.

[0015] Further, in the above-mentioned sequential charging, the addition amount distribution of center coke is based on the addition amount of ore: the addition amount of primary center coke: the addition amount of secondary center coke = the addition amount of primary ore: the addition amount of secondary ore.

[0016] Further, it is set to 3 - 5% in the case of collapse and sliding of the blast furnace.

[0017] Further, it is set to 1.5 - 3% in the case of smooth operation of the blast furnace furnace condition.

[0018] Compared with the prior art, the present invention has the following prominent beneficial effects:

[0019] 1. The device of the present invention stores in separate bins under the trough, measures separately, the pipe belt conveyor feeds independently, and the charging mode of the parallel bins at the furnace top is central coke addition, realizing accurate metering and independent feeding, creating conditions for accurate burden distribution;

[0020] 2. In the process of the present invention, through the coke grading and separation technology and a suitable proportion of high-quality coke in the center, the proportion of high-price high-quality coke in large blast furnaces is reduced, and the proportion of low-price secondary coke is increased, resulting in a significant reduction in the cost of hot metal;

[0021] 3. While reducing the cost of hot metal, the present invention also maintains the stable and smooth operation of the blast furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings of the specification and the specific embodiments.

[0024] For the purposes of the following detailed description, it should be understood that, unless explicitly stated to the contrary, the present invention may assume various alternative variations and step sequences. In addition, except in any operating examples or where otherwise indicated, all numbers representing amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits reported and by applying ordinary rounding techniques.

[0025] Although the numerical ranges and parameters setting forth the broad scope of the present invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviations found in their respective test measurements.

[0026] It should also be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0027] In this application, unless otherwise specifically stated, the use of the singular includes the plural and the plural encompasses the singular. Additionally, in this application, unless otherwise clearly stated, the use of "or" means "and / or", even though in some cases "and / or" may be explicitly used. Further, in this application, unless otherwise specifically stated, the use of "a" or "an" means "at least one". For example, "a" first material, "a" coating composition, etc. refer to one or more of any of these items.

[0028] The present invention relates to a method and device for charging coke into a large blast furnace at low cost.

[0029] As Figure 1 shown, the low-cost large blast furnace coke charging device involved in the present invention.

[0030] It includes: a coke bin, a receiving hopper, a top double-bell and a feeding system. The feeding system includes a main belt feeding assembly and a pipe belt machine feeding assembly. An independent weighing device is provided in each receiving hopper.

[0031] The present invention adopts bin storage under the bunker: the coke bin includes a high-price coke bin and a low-price coke bin.

[0032] There is one high-price coke bin, corresponding to two receiving hoppers, namely the main coke receiving hopper and the central coke receiving hopper 3, which are respectively used for preparing main coke and preparing central coke charging. In the prior art, most of the top of the blast furnaces in other factories are series tanks, and the central coke charging and the main coke are mixed and fed together, so there is no independent weighing device under the bunker, and the amount of central coke charging is determined according to the proportion of the number of rings of the central coke distribution in the coke, which is inaccurate.

[0033] There are three low-price coke bins, which are used to store low-price secondary coke, and each corresponds to a low-price coke receiving hopper.

[0034] The top double-bell includes a main tank 6 and a central coke tank 4. The main tank 6 is a large tank, and the central coke tank 4 is a small tank.

[0035] The feeding system includes a main belt feeding assembly and a pipe belt machine feeding assembly.

[0036] The main belt feeding assembly includes a main belt 1. The upstream of the main belt 1 is the main coke receiving hopper and the low-price coke receiving hopper, and the downstream is the main tank receiving hopper 5 at the top of the furnace. Below the main tank receiving hopper 5 is the main tank 6, which is used for the feeding of main ore (including coke breeze) and main coke.

[0037] The independent pipe belt 2 of the pipe belt machine feeding assembly is parallel to the main belt 1 of the main belt feeding assembly. The upstream of the independent pipe belt 2 is the high-price coke bin, and the downstream is the central coke receiving hopper 3 at the furnace top. Below the central coke receiving hopper 3 is the central coke pot 4, which is specifically used for central coke feeding. In the prior art, it is a single main belt feeding, occupying the feeding process and prone to material shortage in the line. The receiving hoppers are distributed in different ways, including short-range and long-range, which is beneficial for more accurate weighing. The central coke receiving hopper 3 and the central coke pot 4 are distributed in the short range, enabling more precise weighing, while the main coke receiving hopper and the low-price coke receiving hopper are distributed remotely from the main pot 6, facilitating saving the top space and quickly adding coke and ore. The proportional relationship between the high-price coke and the low-price coke fed by the main pot is determined according to on-site requirements and is related to the coke composition, which will not be elaborated here.

[0038] In the optimization plan, the three charging pots at the furnace top are arranged in an isosceles triangle. The two sides are the first main pot and the second main pot, and the middle is the central coke pot 4. Figure 1 The front and rear positions of the first main pot and the second main pot in [description] coincide. The discharge port of the central coke pot 4 is between the discharge ports of the first main pot and the second main pot. The first main pot and the second main pot alternately receive and discharge the main coke and the main ore, which can avoid the problem of material distribution segregation caused by the parallel charging pots.

[0039] The process of the present invention is a method for coke feeding in a large blast furnace with low cost. Through the coke grading and separation technology, a suitable proportion of high-quality central coke is achieved, reducing the proportion of high-price high-quality coke in the large blast furnace and increasing the proportion of low-price secondary coke. While ensuring the stable and smooth operation of the blast furnace, the molten iron cost is significantly reduced.

[0040] The steps of this process invention include:

[0041] 1. Coke grading and separation

[0042] The coke is divided into high-price high-quality coke and low-price secondary coke. The high-price high-quality coke is the top-charged first-class dry quenched coke, and other coke is defined as low-price secondary coke. This simplifies the coke grading and separation standard.

[0043] The coke is stored in bins under the chute: the high-price coke bin stores the high-price high-quality coke, and the low-price coke bin stores the low-price secondary coke. The high-price high-quality coke plays the role of the burden column framework; the secondary-quality coke plays the functions of heat release, carburization, reduction, as well as improving the reduction and heat demand of the ore in the edge area, protecting the furnace lining and playing the heat insulation effect, and promoting the stable and smooth operation of the blast furnace.

[0044] 2. Sequential charging of parallel charging pots at the furnace top

[0045] The three charging pots at the furnace top are arranged in an isosceles triangle. The two sides are the first main pot and the second main pot, and the middle is the central coke pot 4. Figure 1The first main tank and the second main tank are overlapped in the front-back position. The discharging opening of the central coke pot 4 is between the discharging openings of the first main tank and the second main tank. The first main tank and the second main tank are alternately used to receive and discharge main coke and main ore, which can avoid the problem of material distribution segregation caused by parallel tanks.

[0046] The material is distributed in the order of "main coke → central coke → ore → central coke → ore".

[0047] When distributing the central coke, the material line is not discharged, saving time.

[0048] According to different blast furnaces and different equipment, the feeding angle of the central coke is different. The key is to ensure that it neither passes through the launder nor touches the front tension bar of the launder, so as to concentrate the central coke and distribute it to the central area. In this embodiment, the central coke is distributed at an angle of 3°.

[0049] In the case of the three-tank sequential material distribution method at the top of the furnace, even when the addition amount of the central coke is low, it can still effectively ensure that there is no ore in the center, and the addition amount of the central coke is only 10-27% of the existing technology.

[0050] 3. Control of the central coke addition amount

[0051] Control the central coke addition amount to be less than 5% of the coke batch weight. In the optimized plan, when there are collapse and sliding materials in the blast furnace, it is set to 3-5%, which can improve the smoothness of the furnace condition; when the furnace condition of the blast furnace is smooth, it is set to 1.5-3%, which can reduce the consumption of high-quality coke.

[0052] In the order of material distribution of "main coke → primary central coke → primary ore → secondary central coke → secondary ore", the following controls are carried out:

[0053] (1) The addition amount of the primary ore ≥ the addition amount of the secondary ore, and the addition amount of the secondary ore is not less than the critical ore batch weight;

[0054] (2) The distribution of the addition amount of the central coke is based on the addition amount of the ore: the addition amount of the primary central coke: the addition amount of the secondary central coke = the addition amount of the primary ore: the addition amount of the secondary ore.

[0055] The following table shows the comparison of the material distribution methods between the original technology (control example) and the process scheme of the present invention (Examples 1-3):

[0056]

[0057] The following table shows the comparison of the index situations after the start-up of a large blast furnace between the original technology and device, the original technology + the device of the present invention, and the process of the present invention + the device of the present invention. Among them, the original device is a double parallel tank (coke tank, ore tank), and the original technology is the sequential material distribution of "main coke → central coke → ore".

[0058] Utilization factor Fuel ratio kg / t Coal ratio kg / t Proportion of high-price high-quality coke Proportion of low-price secondary coke Prior art + original device 2.301 564.9 152.7 76.73％ 23.27％ Prior art + the device of the present invention 2.532 523.2 159.2 34.45％ 65.55％ The process of the present invention + the device of the present invention 2.608 487.6 168.0 22.66％ 77.34％

[0059] As can be seen from the data in the above table, by adopting the process of the present invention + the device of the present invention, the high-quality coke (top-charged dry quenched coke) in the blast furnace is reduced to 22.66%, and while the center coke charging amount is reduced to 2.2%, the fuel consumption is reduced to 487.6 kg / t; at the same time, the utilization coefficient is also improved.

[0060] Since the ore and coal structures for large and small blast furnaces are the same, the difference in hot metal cost mainly lies in coke. The main gap in coke is the proportion of high-price high-quality coke. By adopting the process of the present invention + the device of the present invention, the hot metal cost is greatly reduced.

[0061] It should be noted that specific embodiments of the present invention have been described in detail. For those skilled in the art, various obvious changes made without departing from the spirit and scope of the present invention are within the protection scope of the present invention.

Claims

1. A method for charging coke in a low-cost large blast furnace, characterized in that: It includes coke grading and separation, top-of-furnace parallel-hopper sequential batching, and control of the central coke charging amount, where: It includes a coke bin, a receiving hopper, top-of-furnace parallel hoppers, and a feeding system; the feeding system includes a main belt feeding assembly and a pipe belt machine feeding assembly; the coke bin includes a high-price coke bin and a low-price coke bin; there is one high-price coke bin, corresponding to two receiving hoppers, a main coke receiving hopper and a central coke receiving hopper, which are respectively used for preparing main coke and preparing central coke charging; the main belt feeding assembly includes a main belt, the upstream of the main belt is the main coke receiving hopper and the low-price coke receiving hopper, and the downstream is the main hopper at the top of the furnace. Below the main hopper is the main tank, which is used for ore and main coke feeding; the independent pipe belt of the pipe belt machine feeding assembly is parallel to the main belt of the main belt feeding assembly. The upstream of the independent pipe belt is the high-price coke bin, and the downstream is the central coke receiving hopper at the top of the furnace. Below the central coke receiving hopper is the central coke tank, which is specially used for central coke feeding; The coke grading and separation is: classifying coke into high-price high-quality coke and low-price secondary coke, and storing them in separate bins under the trough; The top-of-furnace parallel-hopper sequential batching is: batching is carried out in the order of "main coke → central coke → ore → central coke → ore"; the top-of-furnace parallel hoppers are three feeding hoppers, with the first main hopper and the second main hopper on both sides and the central coke hopper in the middle. The discharge port of the central coke hopper is between the discharge ports of the first main hopper and the second main hopper; the first main hopper and the second main hopper take turns receiving and discharging main coke and ore; in the sequential batching, the amount of primary ore added ≥ the amount of secondary ore added, and the amount of secondary ore added is not less than the critical ore batch weight; The control of the central coke charging amount is: controlling the central coke charging amount to be less than 5% of the coke batch weight.

2. The method for charging coke in a low-cost large blast furnace according to claim 1, characterized in that: The high-price high-quality coke is top-charged first-class dry quenched coke, and other coke is defined as low-price secondary coke.

3. The method for charging coke in a low-cost large blast furnace according to claim 1, characterized in that: The three feeding hoppers are arranged in an isosceles triangle.

4. The method for charging coke in a low-cost large blast furnace according to claim 1, characterized in that: No discharge line is set when charging central coke.

5. The method for charging coke in a low-cost large blast furnace according to claim 1, characterized in that: In the sequential batching, the distribution of the amount of central coke added is based on the amount of ore added: the amount of primary central coke added: the amount of secondary central coke added = the amount of primary ore added: the amount of secondary ore added.

6. The method for charging coke in a low-cost large blast furnace according to claim 1, characterized in that: Controlling the central coke charging amount to be less than 5% of the coke batch weight, and setting it to 1.5 - 3% under the condition that the furnace condition of the blast furnace is smooth.

Images