Furnace baking method of Anshan type magnetizing roasting shaft furnace

Abstract

The invention discloses a method for baking an Anshan type magnetizing roasting shaft furnace. The method is suitable for baking operation of the magnetizing roasting shaft furnace after major repair or medium repair. In the roasting process, a 480-hour furnace baking curve is selected, roasted ore and raw ore raw materials are mixed and loaded in a lower-layer combustion chamber, ignition furnace baking is carried out, the temperature in the furnace rises in a stepped mode, normal furnace baking is about to be finished, a reduction chamber is started to form a reduction zone, and transition from the furnace baking curve to a normal curve is achieved. In the furnace baking process, roasted ore and raw ore are mixed in the lower-layer combustion chamber according to the ratio of 1: 2, and impact on refractory materials is reduced; ignition adopts a diagonal crossing mode to ensure that the furnace temperature rises uniformly. And through stepped temperature control, moisture of brick bodies and mortar is slowly discharged, so that the mortar and the clay bricks are sintered into a whole, and deformation or cracking of a furnace body is avoided. The problems that a traditional oven is uneven in temperature and not thorough in water discharge are solved, and the service life of the shaft furnace is remarkably prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical industrial equipment and relates to a furnace baking method for an "Anshan type" magnetized roasting vertical furnace, which is suitable for drying refractory materials in a furnace after overhaul or medium repair. Background Art

[0002] my country's existing vertical furnaces are available in two sizes: 50m³ and 100m³. The first vertical furnace was built in 1926 at the Anshan Iron and Steel Sintering Plant, hence its nickname, the "Anshan-style" vertical furnace. The 100m³ vertical furnace has either a single- or double-combustion chamber. Its dimensions are 12.76 meters long, 5.74 meters wide, and 9.7 meters high. The effective volume is 115m³ for a double-combustion chamber vertical furnace and 147m³ for a single-combustion chamber vertical furnace. The 100m³ vertical furnace is divided into three zones from top to bottom: a preheating zone, a heating zone, and a reduction zone, each with a different function. For large and medium-sized roasting shaft furnaces, since the "Anshan-style" furnace uses different specifications of refractory materials for different temperature zones, and also uses spray coatings and mortar, the moisture content in each temperature zone in the furnace is different, and the furnace drying temperature and time are also different. It is necessary to use a certain temperature and cycle to drain the moisture so that the mortar and clay bricks become a whole and ensure that the furnace body does not deform or crack. However, during the furnace drying process, if the furnace drying is not strictly followed, the furnace body will cause the temperature to be too high in some areas, and the moisture cannot be fully drained, which will affect the service life of the roasting shaft furnace.

[0003] The current drying process of vertical furnaces presents several shortcomings: 1. Temperature control is difficult and uneven due to the varying moisture content of the refractory materials in each temperature zone. 2. The refractory materials are heated unevenly during the drying process, causing deformation of the entire furnace body and the refractory materials in each zone. 3. The drying process significantly damages the furnace lining. During the loaded drying process, raw ore must be used to load the furnace, causing direct impact damage to the newly repaired furnace lining. Summary of the Invention

[0004] The present invention addresses the shortcomings of the aforementioned prior art by providing a baking method for an "Anshan-style" magnetized roasting shaft furnace. This method is suitable for rebuilding the refractory material within a double-combustion chamber shaft furnace during production after major or intermediate repairs. This method slowly and evenly drains moisture from the bricks and mortar, allowing the mortar and clay bricks to sinter into a single unit. This method effectively ensures uniform temperature distribution throughout the furnace, preventing deformation and cracking, and extending the service life of the furnace.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions.

[0006] An "Anshan-style" vertical furnace baking method, a 480-hour staged baking curve is used during the baking process of the double-layer combustion chamber baking furnace: The first stage is to bake the oven with coke oven gas in an empty oven state for a total of 240 hours: the temperature is 20~200℃, and the coke oven gas pressure is not less than 2000KPa; The second stage is the transition from coke oven gas to high coke oven mixed gas, which takes 48 hours in total: the temperature is 200-20℃; The third stage uses high-pressure coke oven mixed gas to bake the oven for a total of 192 hours: the temperature is 200~500℃; In the fourth stage, reducing gas is introduced and normal production is started: the temperature is 900~1200℃.

[0007] In a loaded furnace, roasted ore is used as a bedding material in the lower combustion chamber of the furnace. Raw ore is then mixed in at a ratio of 1:2. This bedding material (the unqualified raw ore that is roasted and then fed into the shaft furnace) effectively reduces the impact of the ore on the refractory material in the reduction zone of the shaft furnace, preventing damage to the lining of the recently repaired furnace. Mixing raw ore in the preheating and heating zones facilitates temperature control in these zones.

[0008] Ignition and furnace baking are carried out in a diagonal cross-interchange manner. By using this diagonal cross-interchange method, the temperature of the preheating zone, heating zone and reduction zone in the furnace can be better controlled, ensuring the temperature balance of each area in the vertical furnace, and avoiding the deformation of the newly built refractory materials in the furnace due to uneven heating, which will affect the service life of the vertical furnace.

[0009] In the early stage of the furnace drying, the temperature in the furnace without raw ore rises in a step-by-step manner and does not need to reach the maximum temperature required by the furnace drying.

[0010] The normal furnace baking is about to end, and the reduction zone gas is started to become the reduction zone, transitioning from the furnace baking curve to the normal curve.

[0011] The method of the present invention can extend the life of the furnace body and prevent chamber sinking and cracking during baking. In particular, the preferential use of roasted ore as a bedding material during loaded charging, mixed with raw ore at a ratio of 1:2, significantly reduces damage to the refractory materials, crossbeams, and ancillary equipment within the furnace body during charging. It also slowly and evenly drains moisture from the bricks and mortar, allowing the mortar and clay bricks to sinter into a single unit. This ensures uniform temperature throughout the furnace body, prevents deformation and cracking, and extends the service life of the roasting shaft furnace.

[0012] Beneficial effects of the present invention: The present invention provides a scientific and efficient "Anshan-style" vertical furnace baking method. By combining a 480-hour staged temperature control curve with an innovative process, it achieves a significant improvement in the structural integrity and service life of the furnace body. This method adopts a step-by-step conversion strategy of coke oven gas and high coke oven mixed gas, combined with a gradual temperature increase design of 20-1200°C, so that the moisture in the refractory bricks and mortar can be slowly and evenly discharged, effectively avoiding the problems of thermal stress concentration and structural deformation caused by traditional rapid baking. The design of a 1:2 mixed loading scheme of roasted ore and raw ore not only protects the newly built refractory materials from ore impact, but also achieves temperature buffering through the roasted ore padding in the lower combustion chamber. The application of diagonal cross ignition technology further ensures the temperature balance of each area of ​​the furnace, and the clear gas pressure (≥2000kPa) and time control parameters form a standardized operating procedure. From the perspective of practical benefits, this method not only solves industry problems such as insufficient slurry sintering and easy cracking of the furnace body, but also reduces maintenance costs by extending the overhaul cycle. Its phased transition to normal production strategy enables the vertical furnace to operate stably after it is put into production. It combines technological advancement with economic benefits, and provides an innovative solution for the maintenance of large vertical furnaces in the metallurgical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the coke oven gas baking curve; Figure 2 This is the high coke oven mixed gas baking curve. DETAILED DESCRIPTION

[0014] The present invention will be further described below through specific embodiments: A method for baking an "Anshan-style" vertical furnace: (1) Develop a scientific baking curve. This curve uses a 480-hour curve to extend the baking time as much as possible, remove moisture from the mortar and clay bricks, and ensure the baking quality. The curve is as follows: The first stage is to bake the oven with coke oven gas in the empty oven state for a total of 240 hours: the temperature is 20~200℃, and the coke oven gas pressure is not less than 2000KPa.

[0015] The second stage is the transition from coke oven gas to high coke oven mixed gas, which takes a total of 48 hours: the temperature is 200~20℃.

[0016] The third stage of high coke oven mixed gas baking is 192 hours in total: temperature 200~500℃ In the fourth stage, reducing gas is introduced and normal production is started: the temperature is 900~1200℃.

[0017] (2) In a loaded drying furnace, after the lower combustion chamber in the furnace is paved with roasted ore, it is mixed with raw ore. The mixing ratio is roasted ore: raw ore = 1:2.

[0018] (3) The ignition and baking furnace are carried out in a diagonal cross manner.

[0019] (4) In the early stage of the furnace drying, the temperature in the furnace without raw ore rises in a step-by-step manner and does not need to reach the maximum temperature required by the furnace drying.

[0020] (5) The normal furnace baking is about to end, and the reduction zone gas is started to become the reduction zone, and the furnace baking curve transitions to the normal curve.

[0021] Example: The gas properties of the 5# roasting vertical furnace in the first selection of Jiugang Ore Dressing are: coke oven gas and high-pressure coke oven mixed gas.

[0022] Specific method of baking oven: (1) The water seal pool before the furnace is dried should be filled with water, and the ore trough on the top of the furnace should be covered tightly with a cover plate and the ore should be pressed.

[0023] (2) Coke oven gas baking oven for 240 hours (20~200℃), coke oven gas pressure is not less than 2000KPa, the specific requirements are as follows: combustion chamber baking oven: ignite two baking oven tubes diagonally in the lower layer, temperature rise to 50℃ in 24 hours, temperature rise to 100℃ in 48 hours, keep warm for 48 hours, after 96 hours, switch the baking oven tubes diagonally and ignite the two baking oven tubes on the upper layer, temperature rise to 150℃ in 120 hours, switch four baking oven tubes, temperature rise to 200℃, keep warm for 24 hours, a total of 168 hours. Coke oven gas baking oven curve is as follows Figure 1 .

[0024] (3) Transition from coke oven gas to blast furnace gas (48 hours in total); 24 hours for natural cooling, and 24 hours for furnace loading and preparation.

[0025] (4) Baking furnace with mixed gas of high coke oven: After turning on the smoke exhaust fan for 15 minutes, turn on the blower, close the air cock valve, and open the air vent pipe; ignite the combustion chamber burners, ignite the heating gas burners one by one, and switch the burners every 4 hours. Heat to 200℃ in 24 hours, and then to 350℃ in 96 hours and keep warm for 24 hours. Then ignite the remaining burners, and increase the temperature by 50℃ every 24 hours on average. The temperature rises to 500℃ in 72 hours. The total baking time is 192 hours. Then, introduce reducing gas and put into production. The baking curve of mixed gas of high coke oven is as follows: Figure 2 .

[0026] The specific requirements for the oven are as follows: (1) After the major or medium repair, the vertical furnace must be dried out. Before the drying out, the vertical furnace chute, furnace door, furnace, and all auxiliary equipment should be thoroughly inspected and tested. The gas, water, air, and steam systems should be checked to see if they are complete and the gas ejection tower should be unobstructed and intact. (2) Preparation for oven baking: ① Cover the ore chute on the furnace roof and cover the top of the square leak with an iron plate; ② Open the rectangular flue covers on both sides one by one and close all gas valves tightly; ③ Install oven baking pipes using coke oven gas in the combustion chambers on both sides; (3) Ignition and baking furnace: ① Turn on the smoke exhauster, light the baking furnace pipe outside the furnace, stop the smoke exhauster, and insert the baking furnace pipe into the combustion chamber; ② Use coke oven gas to bake the furnace, and when the combustion chamber temperature rises to 100-200℃, keep it warm for 2-3 days; ③ Remove the plugging plate of the square leak mouth in the ore chute, and then load the return ore into the furnace or dry the original ore if there is a problem with the return ore, block the drain valve, and fill the water seal pool with water; ④ Remove the gas blind plate at the Φ500 valve gate of the vertical furnace gas branch pipe, open the end of the branch pipe beside the furnace to vent, and guide the gas into the branch pipe until it passes the gas explosion test, and then close the vent; ⑤ Turn on the heating gas burner one by one to heat up the furnace. When the combustion chamber temperature rises to 350-500℃, keep it warm for one week, and remove the baking furnace pipe at an appropriate time; (4) The furnace drying time should be no less than 7-10 days in summer and no less than half a month in winter. When using blast furnace gas to dry the furnace, if the fire eye is hot, you can remove a little of the ore to transfer the heat to the bottom of the furnace. When the removed ore is hot to the touch, you can start the furnace operation.

Claims

1. A method for baking an "Anshan-type" magnetized roasting shaft furnace, characterized in that: Using a 480-hour staged oven curve: The first stage: the coke oven gas is baked for 240 hours in an empty oven state, the temperature is 20-200℃, and the coke oven gas pressure is ≥2000kPa; The second stage: the transition from coke oven gas to high coke oven mixed gas lasts 48 hours at a temperature of 20-200°C; The third stage: baking the oven with mixed gas from high-pressure coke oven for 192 hours at a temperature of 200-500°C; The fourth stage: introducing reducing gas and starting normal production, the temperature is 900~1200℃; After the lower combustion chamber is paved with roasted ore, roasted ore and raw ore are mixed in a mass ratio of 1:2; Ignition and baking of the furnace is carried out in a diagonal cross manner; In the early stage of furnace baking, the temperature in the furnace rises in a step-like manner. At the end of the furnace baking, the reducing gas is started, and the furnace baking curve transitions to the normal production curve.

2. The oven baking method according to claim 1, wherein: The specific operation of the coke oven gas baking furnace in the first stage is: ignite two baking furnace tubes diagonally in the lower combustion chamber, heat up to 50°C in 24 hours, heat up to 100°C in 48 hours and keep warm for 48 hours; after 96 hours, switch the baking furnace tubes and ignite the two upper baking furnace tubes, heat up to 150°C in 120 hours, switch all the baking furnace tubes and heat up to 200°C and keep warm for 24 hours.

3. The oven baking method according to claim 1, wherein: The specific operation of the third stage high coke oven mixed gas baking oven is: ignite the combustion chamber burners at intervals of 1.1, and switch the burners every 4 hours; raise the temperature to 200℃ in the first 24 hours, raise the temperature to 350℃ in 96 hours and keep it warm for 24 hours; then ignite the remaining burners and raise the temperature to 500℃ in 72 hours.

4. The oven baking method according to claim 1, wherein: In the early stage of the baking furnace, the temperature in the furnace rises in a step-by-step manner and does not reach the maximum temperature of the baking furnace; in the late stage of the baking furnace, the reducing gas is started to achieve a smooth transition of the temperature curve to the normal production range.

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