A method for combined treatment of blast furnace slag micro-powder preparation and hot blast furnace flue gas purification

Abstract

The application discloses a blast furnace slag powder preparation and hot blast furnace flue gas purification combined treatment method, and relates to the field of resource recycling. The blast furnace slag powder preparation and hot blast furnace flue gas purification combined treatment method provided by the application is characterized in that: the blast furnace slag after blast furnace treatment is conveyed to a grinding mill to be crushed into blast furnace slag powder, meanwhile, the hot blast furnace flue gas of the blast furnace hot blast furnace is conveyed to the grinding mill to dry the blast furnace slag powder, and the blast furnace slag powder is mixed and reacted to remove sulfur dioxide in the hot blast furnace flue gas; the blast furnace slag powder produced by the grinding mill is collected by a bag dust collector, and then is conveyed to a powder storage bin for storage; and the hot blast furnace flue gas filtered by the bag dust collector is pressurized and discharged through a chimney. The blast furnace slag powder preparation and hot blast furnace flue gas purification combined treatment method provided by the application uses the hot blast furnace flue gas of the blast furnace to dry the water in the blast furnace slag powder, and uses calcium oxide in the blast furnace slag powder to remove sulfur dioxide in the hot blast furnace flue gas, so that energy consumption is saved and carbon and sulfur emission is reduced.

Description

Technical Field

[0001] This application relates to the field of resource recycling, and more specifically, to a method and procedure for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification. Background Technology

[0002] Slag powder is an ultrafine powder obtained by grinding blast furnace slag. It can be used as a high-quality admixture for cement and concrete to increase the added value of slag. However, the grinding and drying hot air in slag powder processing is mostly provided by coal-fired or gas-fired heating furnaces, which consumes a lot of energy and emits a lot of carbon. The secondary flue gas generated by the heating furnace needs further treatment, which makes it difficult to meet environmental protection requirements.

[0003] The SO2 content in the flue gas from the blast furnace hot blast stove is 150 mg / Nm³. 3 The SO2 content does not meet the regulatory requirement of ≤50 mg / Nm³. 3 The requirement is that desulfurization treatment is necessary. Currently, the main desulfurization technologies for hot blast stoves in China include SDS nano-based dry desulfurization, fixed-bed dry desulfurization, and moving-bed dry desulfurization. These methods all have problems such as high initial investment and operating costs, difficulty in handling by-products, and large land area requirements. Summary of the Invention

[0004] The purpose of this application is to provide a method for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification, which uses the hot blast stove flue gas to dry the moisture in the slag powder and uses the calcium oxide in the slag powder to remove sulfur dioxide in the hot blast stove flue gas, thereby saving energy and reducing carbon and sulfur emissions.

[0005] This application is implemented as follows:

[0006] This application provides a method for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification, including the following steps:

[0007] Blast furnace slag after blast furnace treatment is transported to a grinding mill to be crushed into blast furnace slag powder. At the same time, the flue gas from the hot blast stove of the blast furnace is transported to the grinding mill to dry the blast furnace slag powder, and the blast furnace slag powder is mixed and reacted to remove sulfur dioxide from the flue gas from the hot blast stove.

[0008] After collecting the blast furnace slag powder discharged from the grinding mill using a baghouse dust collector, it is transported to the powder silo for storage. The hot blast stove flue gas filtered by the baghouse dust collector is pressurized and discharged through the chimney.

[0009] In some alternative implementations, water mist is sprayed into the hot blast furnace flue gas before it is conveyed to the grinding mill.

[0010] In some alternative implementations, quicklime is added to the blast furnace slag when it is fed into a grinding mill to be pulverized into blast furnace slag powder.

[0011] In some alternative implementations, when quicklime is added into the grinding mill, a bag filter is used to collect the unreacted quicklime discharged from the grinding mill and it is then transported back to the grinding mill using an air chute.

[0012] In some alternative implementations, the following steps are also included: pulverizing baking soda and feeding it into a baghouse dust collector, so that the hot air furnace flue gas entering the baghouse dust collector and the baking soda powder react to remove sulfur dioxide, and using the baghouse dust collector to collect the sodium sulfide generated in the reaction and transport it to a sodium sulfate powder silo for storage.

[0013] In some alternative implementations, the baking soda is pulverized and fed into a baghouse dust collector via a baking soda desulfurization reactor. The flue gas from the hot air furnace is also fed into the baking soda desulfurization reactor, where the flue gas and the pulverized baking soda are mixed and reacted before entering the baghouse dust collector.

[0014] In some alternative implementations, the flue gas from the hot blast stove is cooled to 190-200°C by passing it through a gas preheater and an air preheater, respectively, before being fed into the grinding mill. The gas and air preheated to above 180°C in the gas preheater and air preheater are then fed into the blast furnace hot blast stove.

[0015] In some alternative implementations, the air is heated to 600-800°C using a heating furnace and then mixed with the flue gas from the hot air furnace before it enters the grinding mill, so that the flue gas temperature entering the grinding mill is 280-300°C.

[0016] In some alternative implementations, the blast furnace slag after blast furnace treatment is dried until the moisture content is reduced to below 20% before being fed into a grinding mill for crushing.

[0017] The beneficial effects of this application are as follows: The combined treatment method for blast furnace slag powder preparation and hot blast stove flue gas purification provided by this application includes the following steps: blast furnace slag after blast furnace treatment is conveyed to a grinding mill and pulverized into blast furnace slag powder; simultaneously, the hot blast stove flue gas is conveyed to the grinding mill to dry the blast furnace slag powder, and the blast furnace slag powder is mixed and reacted to remove sulfur dioxide from the hot blast stove flue gas; the blast furnace slag powder discharged from the grinding mill is collected using a bag filter and then conveyed to a powder silo for storage; the hot blast stove flue gas filtered by the bag filter is pressurized and discharged through a chimney. The combined treatment method for blast furnace slag powder preparation and hot blast stove flue gas purification provided by this application uses the hot blast stove flue gas to dry the moisture in the slag powder and utilizes the calcium oxide in the slag powder to remove sulfur dioxide from the hot blast stove flue gas, thereby saving energy and reducing carbon and sulfur emissions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of the method for combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 1 of this application.

[0020] Figure 2 This is a schematic diagram of the blast furnace slag powder preparation and hot blast stove flue gas purification system used in the combined treatment method of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 1 of this application.

[0021] Figure 3 This is a schematic flowchart of the method for combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 2 of this application;

[0022] Figure 4 This is a schematic diagram of the blast furnace slag powder preparation and hot blast stove flue gas purification system used in the combined treatment method of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 2 of this application.

[0023] Figure 5 This is a schematic flowchart of the combined treatment method for blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 3 of this application.

[0024] Figure 6 This is a schematic diagram of the blast furnace slag powder preparation and hot blast stove flue gas purification system used in the combined treatment method of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 3 of this application.

[0025] Figure 7 This is a schematic flowchart of the method for combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 4 of this application;

[0026] Figure 8 This is a schematic diagram of the blast furnace slag powder preparation and hot blast stove flue gas purification system used in the combined treatment method of blast furnace slag powder preparation and hot blast stove flue gas purification provided in Embodiment 4 of this application.

[0027] In the diagram: 100, Raw material silo; 110, Belt conveyor; 120, Vertical grinding mill; 130, Slag quantitative feeder; 140, Hot blast furnace flue gas duct; 150, Baghouse dust collector; 160, Fine ore silo; 170, Micro powder conveying device; 180, Chimney; 190, Exhaust pipe; 200, Exhaust fan; 210, Flue gas pre-processor; 220, Spraying device; 230, Lime silo; 240, Quicklime reactor; 250, Screw feeder; 260, Mixing device; 270, Water supply pipe; 280, Return pipe; 290, Air chute; 300, First shut-off valve; 310, Baking soda silo; 320, Baking soda grinder; 330, Baking soda metering feeder; 340, Conveying pipe; 350, Baking soda desulfurization reactor; 360, Connecting pipe; 370, Second shut-off valve; 380, Flue gas conveying pipe; 390, Third shut-off valve; 400, Gas preheater; 410, Air preheater; 420, Heating furnace; 430, Hot air conveying pipe; 440, Recovery conveying device; 450, Sodium sulfate powder silo; 500, Blast furnace hot blast stove. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The following detailed description of the features and performance of the combined treatment method for blast furnace slag powder preparation and hot blast stove flue gas purification of this application is provided in conjunction with the embodiments.

[0036] Example 1

[0037] like Figure 1 and Figure 2As shown, this application provides a combined method for preparing blast furnace slag powder and purifying hot blast stove flue gas. This method utilizes a blast furnace slag powder preparation and hot blast stove flue gas purification system, which includes a raw material silo 100 for storing blast furnace slag, a belt conveyor 110 for conveying blast furnace slag to the raw material silo 100, a vertical grinding mill 120 for grinding the received blast furnace slag, a slag metering feeder 130 for conveying materials from the raw material silo 100 to the vertical grinding mill 120, and a hot blast stove flue gas discharged from the blast furnace hot blast stove 500 for conveying the flue gas into the vertical grinding mill 120. The system includes a hot blast furnace flue gas duct 140, a bag filter 150 for receiving the grinding products of the vertical grinding mill 120, a powder silo 160, a powder conveying device 170 for conveying the powder collected by the bag filter 150 to the powder silo 160, a chimney 180, an exhaust pipe 190 for conveying the purified flue gas from the bag filter 150 to the chimney 180, and an induced draft fan 200 for pressurizing the flue gas in the exhaust pipe 190. A flue gas pre-processor 210 is provided between the vertical grinding mill 120 and the hot blast furnace flue gas duct 140, and a spray device 220 is provided inside the flue gas pre-processor 210. In this embodiment, the powder conveying device 170 is a pneumatic conveying device.

[0038] The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas provided in this application embodiment is as follows: Blast furnace slag with a moisture content of approximately 25% after blast furnace treatment is piled and dried in a blast furnace slag stockpile and an indoor stockpile until the moisture content decreases to 15-20%. Then, a belt conveyor 110 is used to transport the dried blast furnace slag to a raw material silo 100 for storage. Next, the blast furnace slag in the raw material silo 100 is transported to a vertical grinding mill 120 via a bottom-connected slag metering feeder 130. The slag is then crushed and pulverized in the vertical grinding mill 120 to prepare blast furnace slag powder. Simultaneously, hot blast stove flue gas is transported to the vertical grinding mill 120 via a hot blast stove flue gas pipe 140 connected to the blast furnace hot blast stove 500. Within 20 minutes, the blast furnace slag powder pulverized in the vertical grinding mill 120 is dried using hot blast stove flue gas, reducing the moisture content of the blast furnace slag powder discharged from the vertical grinding mill 120 to about 1%. Finally, the pulverized powder of suitable particle size is discharged from the vertical grinding mill 120 and enters a bag filter dust collector 150 connected to the discharge port of the vertical grinding mill 120. The bag filter dust collector 150 collects the blast furnace slag powder, which is then transported to the powder silo 160 for storage via a powder conveying device 170 connected to the bottom of the bag filter dust collector 150. Simultaneously, the flue gas filtered by the bag filter dust collector 150 is pressurized by an induced draft fan 200 and discharged through an exhaust pipe 190 into a chimney 180. The dust concentration of the discharged flue gas is ≤10mg / Nm³. 3 The micro powder conveying device 170 is a pneumatic conveying device.

[0039] In this process, the flue gas from the hot blast stove is transported through the hot blast stove flue gas pipeline 140 to the flue gas pre-processor 210 for spray treatment before being fed into the vertical grinding mill 120. A spray device 220 sprays water mist into the flue gas pre-processor 210, causing the water mist to react with SO2 in the hot blast stove flue gas to generate H2SO3. This H2SO3 is then fed into the vertical grinding mill 120, where the CaO in the blast furnace slag powder reacts fully with the H2SO3 in the flue gas to generate CaSO3, achieving a flue gas desulfurization effect and ensuring that the SO2 concentration at the chimney outlet 180 is ≤35 mg / Nm³. 3 The temperature of the flue gas from the hot air furnace entering the vertical grinding mill 120 is 280-300℃, and the temperature of the flue gas discharged from the discharge port of the vertical grinding mill 120 is 85-95℃.

[0040] In this embodiment, the filtration velocity of the bag filter 150 is ≤0.65m / min, ensuring that the dust concentration in the flue gas at the outlet of the chimney 180 is ≤10mg / Nm³. 3 It meets the requirements for ultra-low emissions.

[0041] Example 2

[0042] like Figure 3 and Figure 4 As shown, this application provides a method for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification. The difference between the blast furnace slag powder preparation and hot blast stove flue gas purification system used in this method and the blast furnace slag powder preparation and hot blast stove flue gas purification system provided in Example 1 is that, in this example, a lime silo 230, a quicklime reactor 240 for receiving lime in the lime silo 230, and a screw feeder 250 for conveying the material in the quicklime reactor 240 to the feed inlet of the vertical grinding mill 120 are also included. The quicklime reactor 240 is connected to a stirring device 260 and a water supply pipe 270. The bottom of the bag dust collector 150 is connected to an air chute 290 through a return pipe 280. The air chute 290 is used to convey the material in the return pipe 280 to the vertical grinding mill 120. The return pipe 280 is equipped with a first shut-off valve 300.

[0043] The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas provided in this application embodiment involves drying blast furnace slag with a moisture content of approximately 25% after blast furnace treatment in blast furnace slag stockpiles and indoor stockpiles until the moisture content is reduced to 15-20%. Then, a belt conveyor 110 transports the dried blast furnace slag to a raw material silo 100 for storage. Next, the blast furnace slag in the raw material silo 100 is conveyed to a vertical grinding mill 120 via a bottom-connected slag metering feeder 130. The slag is then crushed and pulverized in the vertical grinding mill 120 to prepare blast furnace slag powder. Simultaneously, a hot blast stove flue gas duct 140 connected to the blast furnace hot blast stove 500 is used to transport the hot blast stove flue gas to the vertical grinding mill 120. Within 20 minutes, the blast furnace slag powder pulverized in the vertical grinding mill 120 is dried using hot blast stove flue gas, reducing the moisture content of the blast furnace slag powder discharged from the vertical grinding mill 120 to about 1%. Finally, the pulverized powder of suitable particle size is discharged from the vertical grinding mill 120 and enters a bag filter dust collector 150 connected to the discharge port of the vertical grinding mill 120. The bag filter dust collector 150 collects the blast furnace slag powder, which is then transported to the powder silo 160 for storage via a powder conveying device 170 connected to the bottom of the bag filter dust collector 150. Simultaneously, the flue gas filtered by the bag filter dust collector 150 is pressurized by an induced draft fan 200 and discharged through an exhaust pipe 190 into a chimney 180. The dust concentration of the discharged flue gas is ≤10mg / Nm³. 3 Simultaneously, lime is stored in a lime silo 230, and a quicklime reactor 240 located below the lime silo 230 receives the lime stored in the lime silo 230. Water is added to the quicklime reactor 240 via a water supply pipe 270, and the reaction is stirred by a stirring device 260 to obtain quicklime. Subsequently, a screw feeder 250 transports the quicklime from the quicklime reactor 240 to a vertical grinding mill 120, where the quicklime reacts with H2SO3 in the flue gas of the hot blast stove to produce CaSO3, achieving a flue gas desulfurization effect. The feed rate of the screw feeder 250 is adjusted according to the SO2 concentration discharged from the chimney 180 to ensure that the SO2 content in the flue gas discharged from the chimney 180 is ≤35mg / Nm³. 3 .

[0044] When not producing slag powder, the slag feeder 130 can be stopped from conveying material from the raw material silo 100 to the vertical mill 120. Only the screw feeder 250 is used to convey quicklime from the quicklime reactor 240 to the vertical mill 120. By adjusting the input of quicklime, the SO2 content in the flue gas at the chimney outlet 180 is ensured to be ≤35mg / Nm³. 3 Dust concentration in flue gas ≤10mg / Nm 3When the reaction time is limited and the quicklime cannot completely react with the H2SO3 in the flue gas of the hot blast stove, the first shut-off valve 300 is opened, so that a portion of the unreacted quicklime collected at the bottom of the bag dust collector 150 is transported back to the vertical grinding mill 120 for desulfurization reaction through the return pipe 280 and the air chute 290, and the other portion of quicklime is sent to the powder silo 160 for storage by the micro powder conveying device 170.

[0045] Example 3

[0046] like Figure 5 and Figure 6 As shown, this application provides a method for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification. The difference between the blast furnace slag powder preparation and hot blast stove flue gas purification system used in this method and the system provided in Example 1 is that this embodiment further includes a baking soda silo 310, a baking soda mill 320 for crushing baking soda, a baking soda quantitative feeder 330 for conveying the material in the baking soda silo 310 to the baking soda mill 320 for crushing, and a conveying system for conveying the crushed material from the baking soda mill 320 to the bag filter dust collector 150. A sodium bicarbonate desulfurization reactor 350 is provided between pipe 340, sodium bicarbonate mill 320 and conveying pipe 340. Hot air furnace flue gas pipe 140 and sodium bicarbonate desulfurization reactor 350 are connected by connecting pipe 360. A second shut-off valve 370 for controlling its opening and closing is provided on connecting pipe 360. Flue gas pre-processor 210 and vertical grinding mill 120 are connected by flue gas conveying pipe 380 with a third shut-off valve 390. Bag dust collector 150 is also connected to sodium sulfate powder silo 450 through recovery conveying device 440. In this embodiment, recovery conveying device 440 is a pneumatic conveying device.

[0047] The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas provided in this application embodiment involves drying blast furnace slag with a moisture content of approximately 25% after blast furnace treatment in blast furnace slag stockpiles and indoor stockpiles until the moisture content is reduced to 15-20%. Then, a belt conveyor 110 is used to transport the dried blast furnace slag to a raw material silo 100 for storage. Next, the blast furnace slag in the raw material silo 100 is conveyed to a vertical grinding mill 120 via a bottom-connected slag metering feeder 130. The slag is then crushed and pulverized in the vertical grinding mill 120 to prepare blast furnace slag powder. Simultaneously, a heat exchanger connected to the blast furnace hot blast stove 500 is used... The blast furnace flue gas duct 140 transports the hot blast furnace flue gas to the vertical grinding mill 120. The hot blast furnace flue gas is used to dry the blast furnace slag powder pulverized in the vertical grinding mill 120, reducing the moisture content of the blast furnace slag powder discharged from the vertical grinding mill 120 to 1%. Finally, the pulverized powder of suitable particle size is discharged from the vertical grinding mill 120 and enters a bag filter dust collector 150 connected to the discharge port of the vertical grinding mill 120. The bag filter dust collector 150 collects the blast furnace slag powder, which is then transported to the powder silo 160 for storage via a powder conveying device 170 connected to the bottom of the bag filter dust collector 150. Simultaneously, the flue gas filtered by the bag filter dust collector 150 is also used to dry the powder. After being pressurized by the induced draft fan 200, the gas is discharged through the exhaust pipe 190 into the chimney 180. When the vertical grinding mill 120 malfunctions or is shut down for maintenance, the third shut-off valve 390 on the flue gas conveying pipe 380 between the flue gas pre-processor 210 and the vertical grinding mill 120 is shut off, and the second shut-off valve 370 on the connecting pipe 360 ​​between the hot blast stove flue gas pipeline 140 and the sodium bicarbonate desulfurization reactor 350 is connected. This allows the hot blast stove flue gas conveyed by the hot blast stove flue gas pipeline 140 to bypass the flue gas pre-processor 210 and the vertical grinding mill 120, instead being fed into the chimney through the connecting pipe 360. The sodium bicarbonate desulfurization reactor 350 uses a sodium bicarbonate metering feeder 330 to transport sodium bicarbonate from the sodium bicarbonate silo 310 to a sodium bicarbonate mill 320 for grinding to 20-30μm. The sodium bicarbonate is then transported to the sodium bicarbonate desulfurization reactor 350 to mix and react with the flue gas from the hot blast stove. The reaction causes the sodium bicarbonate and SO2 in the flue gas to react and generate Na2SO4, which is then desulfurized. The Na2SO4 is then transported via a conveying pipe 340 to a bag filter 150. The Na2SO4 is then transported to a sodium sulfate powder silo 450 for storage via a recovery conveying device 440 connected to the bag filter 150. The dust concentration in the flue gas filtered by the bag filter 150 is ≤10mg / Nm³. 3 SO2 content ≤35mg / Nm 3 After being pressurized by the induced draft fan 200, it is discharged from the chimney 180.

[0048] Example 4

[0049] like Figure 7 and Figure 8As shown, this application provides a method for the combined treatment of blast furnace slag powder preparation and hot blast stove flue gas purification. The difference between the blast furnace slag powder preparation and hot blast stove flue gas purification system used in this method and the blast furnace slag powder preparation and hot blast stove flue gas purification system provided in Example 2 is that, in this example, a gas preheater 400, an air preheater 410, a heating furnace 420, and a hot air conveying pipe 430 connecting the heating furnace 420 and the flue gas conveying pipe 380 are also included. One end of the gas preheater 400 and the air preheater 410 are connected to the flue gas pre-processor 210, and the other end is connected to the blast furnace hot blast stove 500.

[0050] The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas provided in this application embodiment involves drying blast furnace slag with a moisture content of approximately 25% after blast furnace treatment in blast furnace slag stockpiles and indoor stockpiles until the moisture content is reduced to 15-20%. Then, a belt conveyor 110 is used to transport the dried blast furnace slag to a raw material silo 100 for storage. Next, the blast furnace slag in the raw material silo 100 is conveyed to a vertical grinding mill 120 via a bottom-connected slag metering feeder 130. The slag is then crushed and pulverized in the vertical grinding mill 120 to prepare blast furnace slag powder. Simultaneously, a gas preheater 400 and an air preheater 410 connected to the blast furnace hot blast stove 500 are used to process the powder. The blast furnace flue gas duct 140 transports the hot blast furnace flue gas to the vertical grinding mill 120. The hot blast furnace flue gas is used to dry the blast furnace slag powder pulverized in the vertical grinding mill 120, reducing the moisture content of the blast furnace slag powder discharged from the vertical grinding mill 120 to approximately 1%. Finally, the pulverized powder of suitable particle size is discharged from the vertical grinding mill 120 and enters a bag filter dust collector 150 connected to the discharge port of the vertical grinding mill 120. The bag filter dust collector 150 collects the blast furnace slag powder, which is then transported to the powder silo 160 for storage via a powder conveying device 170 connected to the bottom of the bag filter dust collector 150. Simultaneously, the flue gas filtered by the bag filter dust collector 150 is pressurized by the induced draft fan 200 and then discharged through the exhaust pipe. The gas enters the chimney at 190°C and exits at 180°C. Through a gas preheater 400 and an air preheater 410 connected to the blast furnace hot blast stove 500, the 280-320°C hot blast stove flue gas inside the blast furnace hot blast stove 500 is divided into two paths. One path passes through the gas preheater 400, preheating the blast furnace hot blast stove 500 to above 180°C with blast furnace gas. The other path passes through the air preheater 410, preheating the blast furnace hot blast stove 500 to above 180°C with combustion air. This increases the temperature of the gas and combustion air entering the blast furnace hot blast stove 500, thereby raising the furnace temperature. Simultaneously, the hot blast stove flue gas, reduced to 190-200°C after passing through the gas preheater 400 and air preheater 410, is further heated... The flue gas from the blast furnace is transported through duct 140 to the flue gas pre-processor 210, where it is sprayed by a spray device 220. The water mist reacts with SO2 in the hot blast furnace flue gas to generate H2SO3. Air is then heated to 600-800℃ using a heating furnace 420 and transported through a hot air conveying pipe 430 to the flue gas conveying pipe 380. This air mixes with the flue gas from the outlet of the flue gas pre-processor 210 and is heated to 280-300℃ before being fed into a vertical grinding mill 120 for turbulent drying of the blast furnace slag powder. During the drying process, the CaO in the slag powder reacts fully with the H2SO3 in the flue gas to generate CaSO3, achieving a desulfurization effect and ensuring that the SO2 concentration at the chimney outlet is ≤35mg / Nm³. 3 .

[0051] In other alternative embodiments, the micro powder conveying device 170 and the recovery conveying device 440 may also be an air chute in conjunction with a bucket elevator.

[0052] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas, characterized in that, Includes the following steps: Blast furnace slag after blast furnace treatment is conveyed to a grinding mill to be crushed into blast furnace slag powder. At the same time, the flue gas from the hot blast stove of the blast furnace is conveyed to the grinding mill to dry the blast furnace slag powder, and to mix and react the blast furnace slag powder to remove sulfur dioxide from the flue gas. Before the flue gas from the hot blast stove is conveyed to the grinding mill, water mist is sprayed into the flue gas through a flue gas pre-processor. The blast furnace slag powder discharged from the grinding mill is collected by a bag dust collector and then transported to the powder silo for storage. The hot blast stove flue gas filtered by the bag dust collector is pressurized and discharged through the chimney. After the baking soda is crushed, it is put into the bag dust collector so that the hot air furnace flue gas entering the bag dust collector and the baking soda powder are mixed and reacted to remove sulfur dioxide. The bag dust collector is used to collect the sodium sulfide generated by the reaction and transport it to the sodium sulfate powder silo for storage. When the grinding mill malfunctions or is shut down for maintenance or repair, the pulverized baking soda is fed into the baghouse dust collector via the baking soda desulfurization reactor. This prevents the hot air furnace flue gas from passing through the flue gas pre-processor and the grinding mill. The hot air furnace flue gas is then introduced into the baking soda desulfurization reactor, where it mixes and reacts with the pulverized baking soda before entering the baghouse dust collector.

2. The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas according to claim 1, characterized in that, When the blast furnace slag after blast furnace treatment is transported to a grinding mill to be crushed into blast furnace slag powder, quicklime is added to the grinding mill.

3. The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas according to claim 2, characterized in that, When quicklime is added into the grinding mill, the bag filter is used to collect the unreacted quicklime discharged from the grinding mill and it is transported back to the grinding mill using an air chute.

4. The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas according to claim 1, characterized in that, The flue gas from the hot blast stove is cooled to 190-200°C by passing it through a gas preheater and an air preheater, respectively, before being fed into the grinding mill. The gas and air preheated to above 180°C in the gas preheater and air preheater are then fed into the blast furnace hot blast stove.

5. The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas according to claim 4, characterized in that, After heating the air in a heating furnace, the air heated to 600-800°C is mixed with the flue gas from the hot air furnace before it enters the grinding mill, so that the temperature of the flue gas entering the grinding mill is 280-300°C.

6. The method for combined preparation of blast furnace slag powder and purification of hot blast stove flue gas according to claim 1, characterized in that, After being processed in the blast furnace, the blast furnace slag is dried until the moisture content is reduced to below 20% before being fed into the grinding mill for crushing.

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