A smelting reduction ironmaking plant

Abstract

The utility model relates to a smelting reduction ironmaking device belongs to smelting reduction ironmaking technical field. Including smelting furnace, composite lance, solid lance, preposition stove, slag port, the upper portion of smelting furnace is gas chamber, and gas chamber is equipped with gas export and composite lance installation mouth, the middle portion lateral wall of smelting furnace is equipped with solid lance, and the iron ore powder and granular coal are blown to the molten pool through solid lance, the lower portion of smelting furnace is molten pool, and the upper layer of molten pool is slag, and the lower layer of molten pool is iron, and the slag layer position is equipped with slag port, the preposition stove is connected with the lower portion of iron layer, the composite lance passes through gas chamber and extends downward to the middle portion of smelting furnace, the composite lance is water -cooling combination spare, and including water -cooling outer cover, water -cooling cyclone insert, baffle, outer ring passageway, inner ring passageway, the carbon-containing powder is blown to outer ring passageway, and oxygen is blown to inner ring passageway. The advantage is that the CO content in the gas increases, and the gas reducing property is enhanced, the bituminous coal is sprayed into the composite lance, the amount of anthracite sprayed into the molten pool is reduced, and the heat consumption of coal cracking in the molten pool is saved.

Description

Technical Field

[0001] This utility model relates to a molten reduction ironmaking apparatus, belonging to the field of molten reduction ironmaking technology. Background Technology

[0002] The smelting reduction furnace directly uses iron ore powder and pulverized coal for ironmaking, eliminating the need for coking and sintering processes. In smelting reduction ironmaking, the ore powder and pulverized coal are directly injected into the slag-iron molten pool, where a reduction reaction occurs, generating CO. The rising CO from the molten pool, along with the injected iron ore powder and pulverized coal carrier gas, carries the molten slag and iron droplets into the upper space, forming a "fountain" of slag and iron droplets. The rising CO gas and the hot air injected from the top hot air lance undergo a secondary combustion reaction, generating a large amount of heat. The heated "fountain" of slag and iron droplets carries this heat back to the molten pool. This secondary combustion reaction is the primary source of heat for the smelting furnace; the large amount of secondary combustion consumes CO in the gas, resulting in a very low calorific value for the gas.

[0003] Current smelting technology involves injecting only oxygen-enriched hot air into the composite blast gun, with an oxygen content of 30-40%. Due to the large amount of nitrogen introduced by the oxygen-enriched blast, the proportion of reducing gas components in the coal gas is low, with only about 23% (CO+H2) in the coal gas. This results in low calorific value and poor reducibility of the coal gas.

[0004] Currently, during the smelting process, all pulverized coal is injected into the molten pool. The carbon (C) from the pulverized coal cracking dissolves into the molten iron, undergoing a reduction reaction of iron oxides at the slag-iron interface to produce molten iron. Only about 60% of the injected carbon is used to reduce iron oxides; the majority rises to the upper part of the molten pool, participating in combustion or being discharged with the coal gas. The pulverized coal injected into the molten pool only achieves good production efficiency and fuel ratio when it is anthracite. Injecting too much pulverized coal into the molten pool results in high-temperature cracking, consuming a large amount of heat from the molten pool.

[0005] Patent CN96193097.7 discloses a method for producing metals and metal alloys, specifically a method and apparatus for producing metals and metal alloys from metal oxides within a smelting vessel comprising a molten pool having a metal layer and a slag layer. The method is characterized by injecting a gas carrier and solid carbon material and / or metal oxides into the molten pool from the side of the vessel in contact with the molten pool or from above the molten pool. These solid particles then penetrate the molten pool and eject molten metal into a gas space above the molten pool, forming a transition zone. Another feature of the method is the injection of oxygen-containing gas into the gas space to perform a secondary combustion reaction on the gas released from the molten pool and entering the transition zone. In this patent, all the solid carbon material is injected into the molten pool.

[0006] Patent CN01101575.6 discloses an apparatus for injecting gas into a metallurgical furnace. The apparatus includes a spray gun with a longitudinally extending airflow duct from the front end to the rear end for discharging gas. An elongated guide rod installed within the front end of the duct is fitted with fluid guide vanes to create a swirling flow in the discharged gas. The nozzle is internally cooled by supply and return water flowing through supply and return water channels. The cooling water passes through the supply and return water channels within the duct and through internal cooling channels located within the vanes and the central guide rod. This patent's gas injection apparatus is for injecting hot air into a metallurgical furnace.

[0007] The disadvantages of the existing technology are: 1. The heat of the smelting furnace mainly comes from the secondary combustion of CO generated by the reaction in the molten pool and oxygen injected by the composite spray gun. The secondary combustion rate is about 55%. Because a large amount of CO in the gas is burned off, the calorific value and reducibility of the gas discharged from the smelting furnace are low. 2. The oxygen content of the gas injected by the composite spray gun is 35-40%, and it contains a large amount of nitrogen, which is also an important reason for the low calorific value of the gas discharged from the smelting furnace. 3. The coal injected into the molten pool needs to have a high carbon content. Only anthracite can be injected effectively, but anthracite is about 20% more expensive than bituminous coal.

[0008] The available publicly available information does not provide solutions to the shortcomings of existing technologies. Summary of the Invention

[0009] Methods for solving technical problems:

[0010] A molten reduction ironmaking apparatus includes a smelting furnace, a composite spray lance, a solid spray lance, a preheating furnace, and a slag outlet;

[0011] The upper part of the smelting furnace is a gas chamber with a gas outlet. The middle part of the smelting furnace is a combustion zone and a heat exchange space. The lower part of the smelting furnace is a molten pool. The upper part of the molten pool is slag, and the lower part of the molten pool is iron. A slag outlet is provided at the slag layer position. The bottom of the iron layer is connected to the preheater.

[0012] The solid spray gun is installed on the middle side wall of the smelting furnace. The solid spray gun is connected to the smelting furnace through a flange. The outlet of the solid spray gun is in the slag layer above the molten pool. The solid spray gun sprays iron-containing materials and carbon-containing particles into the molten pool.

[0013] The composite spray gun is a water-cooled assembly with at least two channels: one channel sprays carbon-containing powder and the other channel sprays oxygen-containing gas. The composite spray gun is installed on the top of the gas chamber or the upper side of the smelting furnace. There is at least one composite spray gun, and the outlet of the composite spray gun is above the molten pool of the smelting furnace. The composite spray gun is connected to the smelting furnace via a flange.

[0014] Preferably, the composite spray gun includes a water-cooled jacket, a water-cooled swirl insert, a baffle, an outer ring channel, and an inner ring channel; the baffle is located between the water-cooled jacket and the water-cooled swirl insert, the baffle and the water-cooled jacket form the outer ring channel, and the baffle and the water-cooled swirl insert form the inner ring channel.

[0015] Preferably, the outer ring channel sprays carbon-containing powder, and the inner ring channel sprays oxygen-containing gas.

[0016] Preferably, there are at least two solid spray guns, and the center line of the solid spray gun is at an angle of 35 to 55° with the center line of the smelting furnace.

[0017] Preferably, the carbon-containing powder is one or more of coal, coke powder, semi-coke powder, biomass pellets, and dry quenching dust, which are ground into powder by a grinding mill. The preferred carbon-containing powder has an average particle size of ≤0.074mm.

[0018] Preferably, the carbon-containing powder is made from high-volatile bituminous coal. The bituminous coal has good combustibility and low cost, and its price is 20% to 30% lower than that of anthracite.

[0019] Preferably, the coal is bituminous coal.

[0020] Preferably, the oxygen-containing gas has an oxygen content of ≥35%.

[0021] Preferably, the oxygen-containing gas has an oxygen content of ≥90%.

[0022] Preferably, the angle between the centerline of the gas outlet and the horizontal line is ≥15°.

[0023] Preferably, the solid spray gun sprays iron-containing material, solvent, and carbon-containing particles into the smelting furnace; the iron-containing material is preferably iron ore powder; the solvent includes lime and dolomite; and the carbon-containing particles include anthracite particles and / or biochar particles.

[0024] During the smelting process, iron ore powder, flux, and pulverized coal are injected into the molten pool through a solid lance. A reduction reaction occurs in the molten pool, producing iron and CO. The rising CO and the injected pulverized coal carry the molten slag and iron droplets into the upper space, forming a "fountain" of slag and iron droplets. The rising CO gas and the hot air injected from the top hot air lance undergo a secondary combustion reaction, generating a large amount of heat. The heated "fountain" of slag and iron droplets are then carried back to the molten pool. The slag in the molten pool is discharged periodically through the slag outlet. The quenched slag is used as building material. The iron in the molten pool is continuously or periodically discharged into a ladle through a preheater and sent to the iron casting machine or steelmaking process. The gas produced by the smelting furnace is discharged from the gas chamber and gas outlet, and after treatment, it is used for the pre-reduction of iron ore powder, as fuel, and for power generation, etc.

[0025] Compared with existing technologies, its advantages are:

[0026] 1. The composite spray gun injects a high oxygen content, which reduces the N2 content in the coal gas and increases its calorific value.

[0027] 2. Carbon-containing powder is injected into the composite spray gun. The coal powder burns in the combustion zone, which reduces the amount of CO burned, increases the CO content in the coal gas, and enhances the reducing power of the coal gas.

[0028] The three-component spray gun injects bituminous coal into the furnace for combustion, providing heat to the smelting furnace and reducing the amount of anthracite injected into the molten pool, thus saving the heat consumed by coal cracking in the molten pool. Attached Figure Description

[0029] Figure 1 It is a molten reduction ironmaking device Figure I

[0030] Figure 2 It is a molten reduction ironmaking device Figure II

[0031] Figure 3 This is a schematic diagram of a composite spray gun.

[0032] Legend markings

[0033] 1. Smelting furnace, 2. Gas chamber, 3. Composite spray gun, 301. Oxygen gas inlet, 302. Pulverized coal inlet, 303. Water-cooled cyclone insert cooling water inlet, 304. Water-cooled cyclone insert cooling water outlet, 305. Water-cooled jacket, 306. Baffle, 307. Water-cooled cyclone insert, 308. Inner ring channel, 309. Outer ring channel, 310. Water-cooled jacket cooling water inlet, 311. Water-cooled jacket cooling water outlet, 312. Cyclone vane, 4. Combustion zone, 5. Slag layer, 6. Iron layer, 7. Solid spray gun, 8. Slag port, 9. Preheater, 10. Gas outlet, 11. Composite spray gun mounting port. Detailed Implementation

[0034] Example 1

[0035] The following is based on Figure 1 , Figure 3 For reference, the implementation of the present invention will be described in detail so that those skilled in the art can easily implement it. The present invention can be embodied in many different forms and is not limited thereto.

[0036] The present invention relates to a molten reduction ironmaking apparatus, comprising a smelting furnace 1, a composite spray lance 3, a solid spray lance 7, a preheater 9, and a slag inlet 8; the upper part of the smelting furnace 1 is a gas chamber 2, which is provided with a gas outlet 10 and a composite spray lance mounting port 11; the large angle of 20° between the centerline of the gas outlet 10 and the horizontal line is conducive to the return of the liquid slag and iron carried in the gas from the gas pipeline into the furnace;

[0037] A solid spray gun 7 is installed on the middle side wall of the smelting furnace 1. Iron ore powder and carbon-containing particles are sprayed into the molten pool through the solid spray gun 7. The lower part of the smelting furnace 1 is the molten pool, the upper layer of the molten pool is the slag layer 5, the lower layer of the molten pool is the iron layer 6, and the slag outlet 8 is provided at the position of the slag layer 3. The lower part of the iron layer 6 is connected to the preheater 9. The middle part of the smelting furnace 1 is the combustion and heat exchange space. The oxygen-containing gas and coal powder injected by the composite spray gun 3 react with the CO generated by the reaction with the molten pool and are burned in the combustion zone 4.

[0038] The solid spray gun has a center line at an angle of 45° to the horizontal line, and its outlet is in the slag layer above the molten iron surface, 200-300 mm away from the molten iron surface. The iron ore powder and carbon particles sprayed in enter the molten iron together under the high-speed impact of the conveying gas.

[0039] The transport gas can be nitrogen, reducing gas, CO2, etc.

[0040] The oxygen-containing gas has an oxygen content of ≥90%. The increased oxygen content significantly increases the combustion temperature, improves the heat transfer efficiency between the high-temperature flue gas and the molten pool, reduces the amount of N2 introduced, increases the calorific value of the generated gas, significantly increases the CO content in the gas, and enhances the reducing properties of the gas, which is beneficial for the pre-reduction of iron ore powder.

[0041] The composite spray lance 3 extends downwards through the gas chamber 2 to the central combustion zone 4 of the smelting furnace. The airflow velocity and height of the outlet of the composite spray lance 3 are crucial. If the position is too high, the combustion zone is too far from the molten pool, resulting in poor heat exchange; if the position is too low, the combustion zone is too close to the molten pool, causing the oxygen in the combustion zone to oxidize the splashed iron from the molten pool and also burn the carbon in the molten pool, resulting in a reverse reaction. The optimal position needs to be adjusted and explored during production. The composite spray lance 3's height can be adjusted; by adjusting the height of the composite spray lance 3, the optimal position can be found. The seal between the composite spray lance 3 and the smelting furnace 1 uses nitrogen gas, which can meet the operating pressure of the smelting furnace 1 at 300 kPa or even higher.

[0042] The composite spray gun 3 is a water-cooled assembly, including a water-cooled jacket 305, a water-cooled swirl insert 307, a baffle 306, an outer ring channel 309, an inner ring channel 308, an oxygen-containing gas inlet 301, a pulverized coal inlet 302, a cooling water inlet 303 for the water-cooled swirl insert 307, a cooling water outlet 304 for the water-cooled swirl insert 307, a cooling water inlet 310 for the water-cooled jacket 305, a cooling water outlet 311 for the water-cooled jacket 305, and a swirl vane 312. The baffle 306 is located between the water-cooled jacket 305 and the water-cooled swirl insert 307, forming the outer ring channel 309 with the baffle 306, and the inner ring channel 308 between the baffle 306 and the water-cooled swirl insert 307. The outer ring channel 309 sprays carbon-containing powder, and the inner ring channel 308 sprays oxygen-containing gas, wherein the oxygen-containing gas has an oxygen content ≥90%. The water-cooled swirl insert 307 has a swirl vane 312 at its end, which allows oxygen to enter the smelting furnace 1 in a swirling manner, effectively improving the mixing and combustion effect of the injected carbon powder and CO in the furnace.

[0043] The carbon-containing powder is made from bituminous coal ground into powder using a grinding mill, with an average particle size ≤0.074mm. Alternatively, the carbon-containing powder can be made from coke powder, dry quenching coke dust, etc., ground into powder using a grinding mill. After being injected into the smelting furnace 1, the carbon-containing powder burns with oxygen in the combustion zone 4, providing heat for smelting. This reduces the secondary combustion rate of the coal gas and also reduces the amount of granular coal injected into the molten pool. The reduction in granular coal injected into the molten pool decreases the heat absorbed by the molten pool due to coal cracking. Furthermore, the carbon-containing powder injected into the composite spray gun 3 is mainly bituminous coal, reducing the amount of carbon-containing particles (mainly granular coal made from anthracite) injected into the molten pool, which can also reduce costs and broaden the range of coal types that can be used.

[0044] The carbon-containing particles are made by drying and crushing a mixture of anthracite, coke powder, semi-coke powder, biochar, etc., with a particle size ≤3mm. Anthracite, semi-coke powder, or biochar can also be used alone.

[0045] During the smelting process in the smelting furnace 1, iron ore powder, solvent, and granular coal are injected into the molten pool through the solid spray gun 7. The reduction reaction of the iron ore powder occurs in the molten pool, generating iron and CO. The CO rising from the molten pool and the conveying gas for injecting iron ore powder and granular coal carry the molten slag and iron droplets into the upper space, forming a "fountain"-shaped slag and iron droplet. The rising CO gas and the oxygen injected by the composite spray gun 3 undergo a secondary combustion reaction, generating a large amount of heat. The "fountain"-shaped slag and iron droplets are heated and carry the heat back to the molten pool. The slag in the molten pool is discharged periodically through slag outlet 8. The quenched slag is used as building material. The iron in the molten pool is continuously or periodically discharged into the molten iron ladle through the preheater 9 and sent to the iron casting machine or steelmaking process. The gas generated by the smelting furnace 1 at a temperature of 1450°C or higher is discharged from the gas chamber and gas outlet. After being used for waste heat utilization in the waste heat boiler and after gas dust removal, it is used for the pre-reduction of iron ore powder, as fuel, and for power generation. Due to the significantly increased oxygen content of the oxygen-containing gas used in smelting, or the use of pure oxygen and compound spray guns to inject bituminous coal, the gas produced by smelting can contain about 70% (CO+H2). Using gas at a temperature of 850°C or higher, and using fluidized bed reduction of iron ore powder, the reduction degree can reach more than 40%, which can greatly improve production efficiency.

[0046] The solvents mentioned are mainly lime, dolomite, etc., used to smelt slag with good fluidity and dephosphorization capability, and the binary basicity (CaO / SiO2) of the slag is ≥1.1.

[0047] Achieved technical specifications:

[0048] Furnace diameter: 6m;

[0049] Secondary combustion rate: 45%

[0050] Oxygen output of the composite spray gun: 500m³ 3 / t;

[0051] The amount of bituminous coal injected by the composite spray gun is 200 kg / t.

[0052] Solid spray gun injection rate of anthracite: 500 kg / t;

[0053] Annual output of smelting furnace: 1.1 million tons.

[0054] Example 2

[0055] Reference Appendix Figure 2 The difference from Example 1 is that the composite spray gun 3 is installed on the side wall of the smelting furnace 1, and there are 4 spray guns. As the production scale expands, the diameter of the smelting furnace 1 is correspondingly expanded. The coverage of one composite spray gun 3 installed in the gas chamber is not enough, so it is necessary to increase the number of composite spray guns 3 and expand the area of ​​the combustion zone 4, which is beneficial to improving the heat exchange efficiency.

[0056] Achieved technical specifications:

[0057] Furnace diameter: 8m;

[0058] Secondary combustion rate: 45%

[0059] Oxygen output of the composite spray gun: 500m³ 3 / t;

[0060] The amount of bituminous coal injected by the composite spray gun is 200 kg / t.

[0061] Solid spray gun injection rate of anthracite: 500 kg / t;

[0062] Annual output of smelting furnace: 2 million tons.

[0063] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A molten reduction ironmaking apparatus, characterized in that, This includes smelting furnaces, composite spray guns, solid spray guns, preheating furnaces, and slag inlets; The upper part of the smelting furnace is a gas chamber with a gas outlet. The middle part of the smelting furnace is a combustion zone and a heat exchange space. The lower part of the smelting furnace is a molten pool. The upper part of the molten pool is slag, and the lower part of the molten pool is iron. A slag outlet is provided at the slag layer position. The bottom of the iron layer is connected to the preheater. The solid spray gun is installed on the middle side wall of the smelting furnace. The solid spray gun is connected to the smelting furnace through a flange. The outlet of the solid spray gun is in the slag layer above the molten pool. The solid spray gun sprays iron-containing materials and carbon-containing particles into the molten pool. The composite spray gun is a water-cooled assembly with at least two channels: one channel sprays carbon-containing powder and the other channel sprays oxygen-containing gas. The composite spray gun is installed on the top of the gas chamber or the upper side of the smelting furnace. There is at least one composite spray gun, and the outlet of the composite spray gun is above the molten pool of the smelting furnace. The composite spray gun is connected to the smelting furnace via a flange.

2. The smelting reduction ironmaking apparatus as described in claim 1, characterized in that, The composite spray gun includes a water-cooled jacket, a water-cooled swirl insert, a baffle, an outer ring channel, and an inner ring channel; the baffle is located between the water-cooled jacket and the water-cooled swirl insert, the baffle and the water-cooled jacket form the outer ring channel, and the baffle and the water-cooled swirl insert form the inner ring channel.

3. The smelting reduction ironmaking apparatus as described in claim 2, characterized in that, The outer ring channel sprays carbon-containing powder, and the inner ring channel sprays oxygen-containing gas.

4. The smelting reduction ironmaking apparatus as described in claim 1, characterized in that, The solid spray guns are at least two in number, and the center line of the solid spray guns is at an angle of 35 to 55° with the center line of the smelting furnace.

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