A COREX method for smelting vanadium-titanium magnetite

Abstract

The invention discloses a COREX method for smelting vanadium-titanium magnetite, which belongs to the field of iron and steel metallurgy, including: using granular coal instead of lump coal to enter the gasifier, increasing the fluidity of granular coal in the molten pool to avoid accumulation; adding thermal crushing, heat recovery, grinding and selection, and granular coal premixing processes to the vanadium-titanium magnetite direct reduced iron produced by the pre-reduction vertical furnace before entering the gasifier, increasing the thermal utilization efficiency of the overall production process, thereby reducing fuel consumption; adding a molten pool side-blowing spray gun, on the basis of circulating the pre-reduction vertical furnace gas to the gasifier, using the pre-reduction vertical furnace venting gas and the converter by-product venting gas for direct blasting. The method of the invention avoids the production and use problems of sintered ore raw materials and coke raw materials, as well as the permeability problem of the soft melting zone, thereby effectively improving the stability and continuity of the smelting process, and effectively reducing the generation of titanium carbonitride, eliminating the problem of reduced effective volume of the blast furnace, and improving the overall utilization rate of the furnace.

Description

Technical Field

[0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a COREX method for smelting vanadium-titanium magnetite. Background Art

[0002] At present, blast furnace ironmaking uses scarce high-quality powdered ore and pulverized coal to produce artificial agglomerates, namely sintered ore and metallurgical coke, through sintering and coking processes. However, there are the following defects when smelting vanadium-titanium magnetite in blast furnace:

[0003] 1. When smelting vanadium-titanium magnetite in a blast furnace, almost all of the TiO 2 It will be enriched in the slag, and about 50% of the vanadium will enter the molten iron, resulting in a low utilization rate of vanadium and titanium resources. Under the action of coke, the titanium-containing blast furnace slag will convert the TiO 2 Reduced to titanium carbide TiC, and under the action of hot air blast, the N in the hot air 2 It will convert TiC into TiN and solid-dissolve with TiC to form titanium carbonitride TiC x N y Solid solution, this high-temperature solid solution will cause the viscosity of blast furnace slag to increase sharply, causing the slag to thicken, making it difficult for the charge to flow downward, thus affecting the smooth operation of the blast furnace. In severe cases, slag will surge from the tuyere or even "freeze the furnace".

[0004] 2. There will be a "dead material pile" formed by the accumulation of coke in the blast furnace hearth. The molten iron and slag will continue to react around the dead material pile to generate titanium carbonitride, which will adhere to the hearth and reduce the effective volume of the hearth.

[0005] 3. When the molten iron mixed with titanium carbonitride enters the ladle, foam slag will appear, causing the molten iron to become viscous and adhere to the wall of the ladle. After several uses, the wall of the ladle will be greatly thickened and the effective volume will be reduced.

[0006] 4. The formation of titanium carbonitride has a great influence on the morphology of the soft melting zone. The soft melting zone of the vanadium-titanium magnetite blast furnace is not the traditional inverted V or W type, but a multi-layer inverted C type with poor air permeability.

[0007] 5. The sintered ore of vanadium-titanium magnetite has poor quality, is prone to reduction and pulverization, and has poor low-temperature reducibility. In addition, there is also high sulfur emission in the production process, which causes environmental pollution.

[0008] 6. In the production process of vanadium-titanium blast furnace, unlike general blast furnace, the furnace temperature cannot be too high, nor can a large proportion of oxygen-enriched injection be used, otherwise it will promote the formation of titanium carbonitride. Therefore, low furnace temperature smelting is required, and low furnace temperature requires low wind temperature, which reduces the difficulty of smelting, but also reduces the smelting intensity. Secondly, the [Si] reduction process in the blast furnace is one of the main sources of heat. The vanadium-titanium blast furnace needs to control the [Ti] / [Si] ratio to achieve "physical heat, chemical cold" blast furnace operation. In the actual production process, this requirement is difficult to achieve because the raw materials are very unstable. In other words, it is feasible to smelt vanadium-titanium magnetite in a blast furnace, but the difficulty is higher than that of a general blast furnace and the conditions are more limited.

[0009] The CO in COREX stands for coal, RE stands for reduction, and EX stands for extreme, which means that the ultimate goal of ironmaking is to use coal reduction directly. Therefore, there is no need for pre-iron processes such as coke and sintered ore. The process and process are relatively long and the process is less, the cost investment and manpower use are relatively low, and the energy consumption and pollution emissions are relatively light. The Ouye furnace inherits the advantages of the blast furnace itself. It includes two parts of the blast furnace. One is the block area at the top of the blast furnace, that is, the pre-reduction shaft furnace part of the Ouye furnace, and the other is the high-temperature melting reduction area of ​​the blast furnace (the lower part of the soft melting zone), that is, the melting gasification furnace part of the Ouye furnace. The entire smelting process still starts from the upper part of the pre-reduction shaft furnace, and lump ore, pellet ore, and slag-making solvent are added, which react indirectly with the high-temperature furnace gas added in the middle to generate sponge iron. Then, sponge iron and lump coal are added to the upper part of the melting gasification furnace, and oxygen or oxygen-enriched air is blown into the middle and lower parts to form a high-temperature oxygen-enriched environment. Finally, the slag and iron are separated in the lower part. The Ouye furnace can be regarded as an open blast furnace without a "soft melting zone" and has excellent air permeability. As a whole, it is a high-filling-rate metallurgical reactor like a blast furnace. The main equipment has added a furnace gas purification and temperature control system, and the utilization rate of secondary energy is high. However, the Ouye furnace still has obvious disadvantages. First, the coal ratio is very high, generally reaching 950kg / t-Fe, which is more than 1.5 times the coke ratio (converted) of the existing equivalent blast furnace. This is because the sponge iron reduced by the pre-reduction vertical furnace needs to reabsorb higher heat to melt, and sometimes it is necessary to spray cold coal powder from the side of the gasifier dome to supplement the heat. Therefore, the role of providing heat to maintain the temperature of the molten pool through the combustion of non-coking coal is increased, so the consumption increases. Second, the coal lumps accumulate at the bottom of the molten pool, forming a "dead material pile" like the one in the blast furnace hearth. The permeability of the dead material pile determines whether the slag iron can pass through the dead material pile well and flow to the iron mouth from all directions to be discharged from the furnace, or whether it cannot pass through the dead material pile well and mainly circulates along the furnace wall to be discharged from the furnace. The former has good furnace activity, stable slag iron liquid level, uniform iron tapping time, weaker scouring of the furnace wall, and significantly extends the life of the blast furnace. The lump coal of the Ouye furnace is non-coking coal with poor liquid permeability. Third, pure oxygen blast is highly corrosive to the carbon-containing furnace lining, and further oxidizes the molten iron. The temperature inside the gasifier is uneven, and the amount of furnace gas smoke is large, which increases the difficulty of subsequent furnace gas treatment.

[0010] The use of Ouye furnace to smelt vanadium-titanium magnetite avoids the problem of soft melting zone permeability in the blast furnace smelting process. At the same time, there is no need to use sintered ore and coke, which greatly reduces energy consumption and pollutant emissions. In addition, the use of pure oxygen injection blast avoids the formation of titanium nitride and also inhibits the formation and re-oxidation of titanium carbide, thereby improving the high-temperature metallurgical physical and chemical properties of titanium-containing blast furnace slag, especially improving the wettability and fluidity of the slag. However, there are still several important issues that affect the smelting of vanadium-titanium magnetite:

[0011] 1. There is still a large amount of titanium carbide generated, which makes it difficult to separate foamy slag and slag iron. Since the way of tapping iron in Ouye furnace is to drill the iron mouth regularly, the mixture of foamy slag and slag iron can easily cause the iron mouth to gush out. In addition, titanium carbide is generated by attaching to the dead material pile. Titanium carbide and coal have good wettability, which will adhere to coal particles and enter the slag iron. It will continue to react in the ladle, forming the problem of foamy slag and thickening of the ladle.

[0012] 2. The heat demand in the furnace is large, and pure oxygen needs to be sprayed to burn pulverized coal, which is costly and has a high coal ratio. Moreover, when lump coal and sponge iron are mixed and added to the molten pool, the combustion effect of the lump coal in the molten pool cannot be fully exerted, and it can only serve as a reducing agent, which can easily cause the titanium oxide in the titanium-containing blast furnace slag to be over-reduced to titanium carbide. When drilling the iron hole to discharge slag iron, in order to maintain the temperature of the furnace body, pulverized coal must continue to be burned, which can easily cause problems such as furnace gas leakage.

[0013] 3. When the Ouye furnace melting gasifier is in service, in order to save fuel and produce high-quality furnace gas, cold coal powder is blown into the side of the gasifier arch. The blown cold coal powder directly impacts the arch, causing a large area of ​​​​stripping of the arch refractory material, which brings hidden dangers to the safe production of Ouye furnace.

[0014] 4. Pure oxygen injection will increase the FeO content in the slag, that is, the molten iron is oxidized and the iron loss increases.

[0015] It should be mentioned that the law of generating titanium carbonitride from blast furnace smelting of vanadium-titanium magnetite shows that titanium nitride in titanium carbonitride is obtained by nitriding titanium carbide. If the content of titanium carbide is not reduced, the impact on titanium-containing blast furnace slag is still obvious. One of the sufficient conditions for reducing the formation of titanium carbide is to increase the partial pressure of CO, and the necessary condition is to increase the oxygen potential. Summary of the invention

[0016] In view of the above-mentioned problems, the present invention discloses a method for smelting vanadium-titanium magnetite by COREX. It includes the following methods: first, using granular coal instead of lump coal to enter the gasifier, increasing the fluidity of granular coal in the molten pool and avoiding accumulation. Secondly, before the vanadium-titanium magnetite direct reduced iron produced by the pre-reduction vertical furnace enters the gasifier, hot crushing, heat recovery, grinding and selection, and granular coal premixing processes are added to increase the thermal utilization efficiency of the overall production process, thereby reducing fuel consumption. Hot crushing refers to the crushing of furnace charge at a temperature of 200-500°C, with low crushing difficulty and high efficiency, and a heat recovery process is added at the same time. After cooling, it is premixed with cold granular coal. Thirdly, a molten pool side-blowing lance is added, and on the basis of circulating the pre-reduction vertical furnace gas to the gasifier, the pre-reduction vertical furnace venting gas and the converter by-product venting gas are added for direct blasting, thereby improving the furnace gas quality, and no additional furnace gas heat recovery system is added, while increasing the heat supply of the Ouye furnace, reducing carbon consumption, and strengthening the molten pool stirring, increasing the oxygen potential in the furnace, and reducing the dust in the furnace gas.

[0017] A COREX method for smelting vanadium-titanium magnetite, specifically comprising the following steps:

[0018] (1) Pre-reduction: The vanadium-titanium magnetite concentrate is prepared into pellets and lump ore, or self-fluxing pellets with a binary basicity in the range of 1.0-1.3 are prepared, and then reduced by the furnace gas generated by the melt gasifier in the COREX pre-reduction shaft furnace to obtain the reducing material. The main components and contents of the reducing material are TFe 60-75%, TiO 2 15~25%, V 2 O 5 0.5~1.5%, Cr 2 O 3 0.5~1.5%; During the pre-reduction process, the iron oxides in the raw materials are reduced to metallic iron and low-oxidation vanadium-titanium compounds. The temperature in the pre-reduction shaft furnace is maintained between 1000~1250℃ to ensure the effective reduction reaction;

[0019] (2) Hot crushing and grinding: After the high-temperature reducing material passes through the water-cooled heat exchanger at the discharge port and is cooled, the reducing material at a temperature of 200-500°C is sent to the crusher through a conveyor for crushing. The average particle size of the crushed reducing material is 10-30mm, and the temperature is 60-90°C. The crushed and cooled raw materials are ground to select vanadium-rich titanium materials and reduced iron, and the vanadium-rich titanium materials are sent to the wet process for vanadium and titanium extraction. The composition and content of the vanadium-rich titanium materials after grinding are TFe 5-20%, TiO 2 30~50%, V 2 O 5 1~3%, Cr 2 O 3 0.5~1.5%. The composition and content of reduced iron are TFe 90~99%, TiO 2 5~15%, V 2 O 5 0.05~0.25%, Cr 2 O 3 0.5~1.5%;

[0020] (3) Raw material premixing: The crushed and ground direct reduced iron particles are premixed with granular coal. The granular coal used is non-coking coal or semi-coke (lignite), and the average particle size of the granular coal is 5-30 mm. After mixing, the mixture is stored in the silo for standby use;

[0021] (4) Gasification and melting reduction: The premixed raw materials are added to the melting gasifier, and the molten pool temperature is maintained above 1450°C by spraying coal powder, heavy oil or natural gas and pure oxygen through the spray gun. The slag composition is adjusted by controlling the atmosphere in the furnace and adding solvents, such as TiO in the slag. 2If the content is too high, more than 10%, high-grade iron ore powder or CaO, SiO 2 , MgO and other oxidizing solvents. When the furnace temperature is too high, reduce the intensity of fuel injection. When slag is discharged and iron is discharged, increase the injection of high-temperature furnace gas to maintain the molten pool temperature. Maintaining TiO in the slag 2 Content 5~10%, titanium carbonitride content 1~5%, viscosity 0.1~1.5Pa·s. TFe in molten iron 95~99%, TiO 2 0.1~1%, V 2 O 5 0.1~0.5%, Cr 2 O 3 1~3%. The molten iron and slag are discharged separately through their respective discharge ports. The molten iron is further fed into the steelmaking process, while the slag is recycled as a by-product.

[0022] (5) Side blowing of vented gas: The gas generated in the entire pre-reduction vertical furnace process is directly recovered and mixed with the vented gas generated by the basic oxygen converter in the relay hot blast furnace at a volume fraction of 20-80%. The position of the vented gas gun is adjusted and the vented gas is sprayed into the slag-iron interface layer. The composition (volume fraction%) of the vented gas from the converter is CO 20-40%, CO 2 30~40%, the rest is N 2 , the temperature is 900~1100℃. The gas composition (volume fraction%) of the pre-reduction shaft furnace is CO 20~40%, CO 2 40~70%, the rest is CH 4 、SO 2 , H 2 wait.

[0023] In the early stage of smelting, the thickness of the slag layer and the molten iron layer are relatively shallow. At this time, the slag-metal liquid level is about 900~1200mm, the ratio of the slag layer thickness to the molten iron layer thickness is 0.4~0.6, the side-blowing gun angle is about 65~85°, the gauge pressure is 0.1~0.25MPa, and the gas supply intensity is 0.8~1.6 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 50~80%, CO30~40% in the mixed injection gas, CO 2 30~40%, the remaining main components are CH 4 , H 2 The mixed gas temperature is 800~1000℃, the slag and iron stirring is less intense, the reduction potential is high, and it is in the initial reduction slag-making period. The slag phase gradually increases, and the molten iron layer gradually becomes thicker. However, due to the addition of a large amount of cold charge, the overall temperature of the furnace body and the molten pool is relatively low, about 1350~1450℃;

[0024] In the middle stage of smelting, the thickness of slag layer and molten iron layer reaches 1500~1800mm, the ratio of slag layer thickness to molten iron layer thickness is 0.6~0.8, the side blowing gun angle is about 45~65°, the gauge pressure is 0.25~0.45MPa, and the gas supply intensity is 1.8~2.8 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 40~60%, CO in the mixed injection gas is 25~35%, CO 2 35~45%, the remaining main components are N 2 The mixed gas temperature is 800-1000℃. At this time, the slag-iron interface reacts violently, a large number of metal elements are reduced, the thickness of the slag layer and the molten iron layer increases further, the side blowing stirring effect is intense, and the slag-iron interface layer forms a "spring-like" stirring vortex. The granular coal in the molten pool and the CO 2 The reaction generates CO gas, which overflows to the combustion zone above the molten pool and burns. The overall temperature of the furnace body and the molten pool rises to 1600~1800℃;

[0025] At the end of smelting, the thickness of the slag layer and the molten iron reached 2000~2500mm, the ratio of the slag layer thickness to the molten iron layer thickness was 1.0~1.3, the side-blowing lance angle was about 25~45°, the gauge pressure was 0.15~0.25MPa, and the gas supply intensity was 1.0~2.0 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 20~50%, CO in the mixed injection gas is 20~30%, CO 2 40~50%, the remaining main components are N 2 The mixed gas temperature is 800~1000℃, at which time the slag-iron interface reaction activity is reduced, the injection intensity is reduced, and the CO 2 The ratio can reduce the intensity of the molten pool reaction and the furnace gas dust, promote the separation of the slag layer and the molten iron layer, and make full use of the physical heat of the furnace gas to supplement the heat of the furnace body, reduce the injection intensity of the fuel, and the overall temperature of the furnace body and the molten pool is still maintained at 1600~1800℃;

[0026] During the slag and iron discharge stage, the furnace temperature drops to about 1350~1450℃ and the thickness of the slag iron layer drops to below 900mm due to the heat taken away by the molten iron and slag. At this time, the amount of diffused furnace gas injection can be appropriately increased to maintain the molten pool temperature. The angle of the spray gun is adjusted between 15~30° and located above the molten pool. The proportion of converter diffused furnace gas in the injected mixed gas is about 45~75%, and the gas supply intensity is 1.3~2.3 m 3 / (t·min), CO 25~35% in the mixed gas, CO 2 35~45%, the remaining main components are N 2The furnace gas temperature is 800-1000℃, the molten pool is not stirred, the air pressure above the molten pool is increased compared with that without the side-blowing lance, the slag and iron removal speed is accelerated, the production efficiency is increased, and the furnace body and the molten pool temperature can be maintained at 1450-1550℃. Among them, the vented furnace gas refers to the furnace gas generated in the converter production process, which is burned and released into the atmosphere because the average CO content is less than 40% and cannot meet the recovery standard. The furnace gas of the general pre-reduction vertical furnace also belongs to the low calorific value furnace gas. In the present invention, it is used as one of the self-circulating injection fuels to improve the energy utilization rate of the system.

[0027] In the step (1), the main components and contents (mass percentage %) of the vanadium-titanium magnetite used are TFe 30-55%, TiO 2 9~15%, V 2 O 5 0.3~0.8%,Cr 2 O 3 0.1~0.5%. The main components and content of vanadium-titanium magnetite concentrate are TFe55~65%, TiO 2 15~25%, V 2 O 5 0.5~1.5%, Cr 2 O 3 0.5~1.5%, the rest is SiO 2 、CaO、Al 2 O 3 , MgO, etc.

[0028] In the step (2), the high-temperature raw material is cooled by heat exchange in the water-cooled heat exchanger at the discharge port to prevent damage to the conveying device and the crushing device caused by excessive temperature.

[0029] In the step (2), the reducing material at a temperature of 200-500° C. is sent to the crusher through a conveyor for crushing. The furnace charge is crushed at a temperature of 200-500° C., with low crushing difficulty and high efficiency. At the same time, a heat recovery process is added.

[0030] In the step (2), the grinding process is to grind the ore into a certain particle size of ore powder, and then separate the reduced iron from the vanadium-rich titanium material by gravity separation, strong magnetic separation, weak magnetic separation, etc.

[0031] In the step (3), the crushed and ground direct reduced iron particles are premixed with granular coal, and the coal-iron mass ratio is preferably 0.4-1. The mixing ratio of coal and iron is determined based on economic efficiency.

[0032] In the step (4), the premixed raw materials are added to the melter-gasifier, and the temperature of the molten pool is maintained at 1450-1530° C. by burning fuels such as pulverized coal, heavy oil or natural gas and pure oxygen through a spray gun.

[0033] In the step (4), the current average viscosity index of the all-vanadium titanium blast furnace slag is 1~3Pa·s, generally 2.5Pa·s, while the viscosity fluidity of the blast furnace slag is about 0.5Pa·s, and it will deteriorate when it exceeds 1Pa·s. The vanadium titanium blast furnace has the particularity that the slag is relatively viscous.

[0034] In step (5), the vented gas refers to a portion of the gas that is not recycled by the enterprise, because CO 2 High content and CO content that does not meet the standard result in low calorific value, which is generally directly ignited and released into the atmosphere, so it is called released furnace gas. The CO content compliance rate described in the present invention is based on 40%.

[0035] In the step (5), the pre-reduction vertical furnace venting furnace gas and the converter by-product venting furnace gas are used for direct blasting to improve the furnace gas quality without adding an additional furnace gas heat recovery system. While increasing the heat supply of the Ouye furnace, carbon consumption is reduced, and the stirring of the molten pool is enhanced, the oxygen potential in the furnace is increased, and the dust in the furnace gas is reduced.

[0036] Beneficial effects of the present invention:

[0037] 1. Ouye furnace replaces the traditional blast furnace to smelt vanadium-titanium magnetite, avoiding the production and use problems of sintered ore raw materials and coke raw materials, as well as the permeability problem of the soft melting zone, thereby effectively improving the stability and continuity of the smelting process.

[0038] 2. Effectively reduce the amount of titanium carbonitride generated, eliminate the problem of reduced effective volume of the blast furnace, and improve the overall utilization rate of the furnace.

[0039] 3. After thermal crushing, the heat inside the charge can be released more fully, increasing the amount of waste heat recovery and energy utilization.

[0040] 4. After the pre-reduction vertical furnace produces the reduced raw materials, the thermal crushing and grinding processes are added to increase the process energy recovery. At the same time, the vanadium-containing and titanium-rich materials are separated, which greatly improves the recovery rate of vanadium and titanium resources in vanadium-titanium magnetite.

[0041] 5. The molten pool side blowing is added to directly act on the slag-iron interface, stirring the molten pool, promoting the uniform distribution of coal particles, avoiding the formation of dead material piles, and improving the reactivity of the molten pool.

[0042] 6. The injection gas is CO and CO 2 The mixed exhaust gas with a high content from the converter and pre-reduction vertical furnace increases the secondary recycling rate of the system's by-product energy and reduces the system's energy consumption and carbon emissions.

[0043] 7. The physical heat of the released furnace gas is fully utilized to provide non-combustion external heating to the furnace body and the molten pool, thus reducing fuel consumption, lowering production costs, and improving the energy utilization rate of the system.

[0044] 8. Make full use of the CO in the released furnace gas 2 Regulating the production process, CO 2 As a weak oxidant, it can increase the oxygen potential at the slag-iron interface and inhibit the oxidation of TiO 2 While over-reducing to TiC, the molten iron will not be over-oxidized to FeO.

[0045] 9. In addition to providing a portion of CO in the vented furnace gas, CO 2 It will also react with the granular coal in the molten pool to generate CO. Due to the barrier of the slag layer, the partial pressure of CO at the slag-metal interface will increase significantly, which will further inhibit the formation of TiC, which will significantly improve the high-temperature metallurgical physical and chemical properties of titanium-containing blast furnace slag, especially improve fluidity.

[0046] 10. Even if the mixed gas contains N 2 The conversion amount of TiN will also decrease due to the reduction of TiC content, and TiN, as a beneficial nitride inclusion, has a beneficial effect on the subsequent steel smelting.

[0047] 11. Release CO in furnace gas 2 It can reduce the intensity of molten pool gushing and reduce the dust in the flue gas. At the same time, its stirring effect is equivalent to Ar. Strengthening the stirring effect of the molten pool helps to improve the reaction efficiency, reduce the dust content in the furnace gas, reduce the impact on the pre-reduction vertical furnace, and effectively reduce the risk of furnace gas flue blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the side-blowing structure of COREX smelting vanadium-titanium magnetite.

[0049] Figure 2 Schematic diagram of the COREX process for smelting vanadium-titanium magnetite. DETAILED DESCRIPTION

[0050] A COREX method for smelting vanadium-titanium magnetite, such as Figure 1-2 As shown, the specific steps include:

[0051] (1) Pre-reduction: The main components and content of vanadium-titanium magnetite concentrate are TFe 55~65%, TiO 2 15~25%, V 2 O 5 0.5~1.5%, Cr 2 O 3 0.5~1.5%, the rest is SiO 2、CaO、Al 2 O 3 , MgO, etc. The vanadium-titanium magnetite concentrate is prepared into pellets and lump ore, or self-fluxing pellets with a binary basicity of 1.0-1.3 are prepared, and then reduced by the furnace gas generated by the melt gasifier in the COREX pre-reduction shaft furnace to obtain a reducing material. The main components and contents of the reducing material are TFe 60-75%, TiO 2 15~25%, V 2 O 5 0.5~1.5%, Cr 2 O 3 0.5~1.5%; During the pre-reduction process, the iron oxides in the raw materials are reduced to metallic iron and low-oxidation vanadium-titanium compounds. The temperature in the pre-reduction shaft furnace is maintained between 1000~1250℃ to ensure the effective reduction reaction;

[0052] (2) Hot crushing and grinding: After the high-temperature reducing material passes through the water-cooled heat exchanger at the discharge port and is cooled, the reducing material at a temperature of 200-500°C is sent to the crusher through a conveyor for crushing. The average particle size of the crushed reducing material is 10-30mm, and the temperature is 60-90°C. The crushed and cooled raw materials are ground to select vanadium-rich titanium materials and reduced iron, and the vanadium-rich titanium materials are sent to the wet process for vanadium and titanium extraction. The composition and content of the vanadium-rich titanium materials after grinding are TFe 5-20%, TiO 2 30~50%, V 2 O 5 1~3%, Cr 2 O 3 0.5~1.5%. The composition and content of reduced iron are TFe 90~99%, TiO 2 5~15%, V 2 O 5 0.05~0.25%, Cr 2 O 3 0.5~1.5%;

[0053] (3) Raw material premixing: The crushed and ground direct reduced iron particles are premixed with coal particles. The coal-iron mass ratio is preferably 0.4-1. The coal particles used are non-coking coal or semi-coke (lignite). The average particle size of the coal particles is 5-30 mm. After mixing, the mixture is stored in the silo for later use.

[0054] (4) Gasification and smelting reduction: The premixed raw materials are added to the melt gasifier, and the molten pool temperature is maintained at 1450~1530℃ by spraying coal powder, heavy oil or natural gas and pure oxygen through the spray gun. The slag composition is adjusted by controlling the atmosphere in the furnace and adding solvents, such as TiO in the slag. 2 If the content is too high, more than 10%, high-grade iron ore powder or CaO, SiO 2, MgO and other oxidizing solvents. When the furnace temperature is too high, reduce the intensity of fuel injection. When slag is discharged and iron is discharged, increase the injection of high-temperature furnace gas to maintain the molten pool temperature. Maintaining TiO in the slag 2 Content 5~10%, titanium carbonitride content 1~5%, viscosity 0.1~1.5Pa·s. TFe in molten iron 95~99%, TiO 2 0.1~1%, V 2 O 5 0.1~0.5%, Cr 2 O 3 1~3%. The molten iron and slag are discharged separately through their respective discharge ports. The molten iron is further fed into the steelmaking process, while the slag is recycled as a by-product.

[0055] (5) Side blowing of vented gas: The gas generated in the entire pre-reduction vertical furnace process is directly recovered and mixed with the vented gas generated by the basic oxygen converter in the relay hot blast furnace at a volume fraction of 20-80%. The position of the vented gas gun is adjusted and the vented gas is sprayed into the slag-iron interface layer. The composition (volume fraction%) of the vented gas from the converter is CO 20-40%, CO 2 30~40%, the rest is N 2 , the temperature is 900~1100℃. The gas composition (volume fraction) of the pre-reduction shaft furnace is CO 20~40%, CO 2 40~70%, the rest is CH 4 、SO 2 , H 2 The specific spraying method is as follows:

[0056] In the early stage of smelting, the thickness of the slag layer and the molten iron layer are relatively shallow. At this time, the slag-metal liquid level is about 900~1200mm, the ratio of the slag layer thickness to the molten iron layer thickness is 0.4~0.6, the side-blowing gun angle is about 65~85°, the gauge pressure is 0.1~0.25MPa, and the gas supply intensity is 0.8~1.6 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 50~80%, CO30~40% in the mixed injection gas, CO 2 30~40%, the remaining main components are CH 4 , H 2 , the mixed gas temperature is 800~1000℃, the slag and iron stirring is less intense, the reduction potential is high, it is in the initial reduction slag-making period, the slag phase gradually increases, and the molten iron layer gradually becomes thicker. However, due to the addition of a large amount of cold charge, the overall temperature of the furnace body and the molten pool is relatively low, about 1350~1450℃;

[0057] In the middle stage of smelting, the thickness of slag layer and molten iron layer reaches 1500~1800mm, the ratio of slag layer thickness to molten iron layer thickness is 0.6~0.8, the side blowing gun angle is about 45~65°, the gauge pressure is 0.25~0.45MPa, and the gas supply intensity is 1.8~2.8 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 40~60%, CO in the mixed injection gas is 25~35%, CO 2 35~45%, the remaining main components are N 2 The mixed gas temperature is 800-1000℃. At this time, the slag-iron interface reacts violently, a large number of metal elements are reduced, the thickness of the slag layer and the molten iron layer increases further, the side blowing stirring effect is intense, and the slag-iron interface layer forms a "spring-like" stirring vortex. The granular coal in the molten pool and the CO 2 The reaction generates CO gas, which overflows to the combustion zone above the molten pool and burns. The overall temperature of the furnace body and the molten pool rises to 1600~1800℃;

[0058] At the end of smelting, the thickness of the slag layer and the molten iron reached 2000~2500mm, the ratio of the slag layer thickness to the molten iron layer thickness was 1.0~1.3, the side-blowing lance angle was about 25~45°, the gauge pressure was 0.15~0.25MPa, and the gas supply intensity was 1.0~2.0 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 20~50%, CO in the mixed injection gas is 20~30%, CO 2 40~50%, the remaining main components are N 2 , the mixed gas temperature is 800~1000℃, at this time, the slag iron interface reaction activity is reduced, the injection intensity is reduced, and the CO 2 The ratio can reduce the intensity of the molten pool reaction and the furnace gas dust, promote the separation of the slag layer and the molten iron layer, and make full use of the physical heat of the furnace gas to supplement the heat of the furnace body, reduce the injection intensity of the fuel, and the overall temperature of the furnace body and the molten pool is still maintained at 1600~1800℃;

[0059] During the slag and iron discharge stage, the furnace temperature drops to about 1350~1450℃ and the thickness of the slag iron layer drops to below 900mm due to the heat taken away by the molten iron and slag. At this time, the amount of diffused furnace gas injection can be appropriately increased to maintain the molten pool temperature. The angle of the spray gun is adjusted between 15~30° and located above the molten pool. The proportion of converter diffused furnace gas in the injected mixed gas is about 45~75%, and the gas supply intensity is 1.3~2.3 m 3 / (t·min), CO 25~35% in the mixed gas, CO 2 35~45%, the remaining main components are N 2The furnace gas temperature is 800~1000℃, there is no stirring in the molten pool, the air pressure above the molten pool is higher than that without a side-blowing spray gun, the slag and iron discharge speed is accelerated, the production efficiency is increased, and the furnace body and molten pool temperature can be maintained at 1450~1550℃.

[0060] Comparative Example 1: Blast Furnace Smelting of Vanadium Titanium Magnetite

[0061] Objective: To study the smelting effect of vanadium-titanium magnetite in conventional blast furnace.

[0062] Mineral composition: The main components and content of vanadium-titanium magnetite concentrate are TFe: 60%, TiO 2 :25%,V 2 O 5 :1.5%.

[0063] Raw material particle size: 10~20mm.

[0064] Smelting temperature: 1530℃.

[0065] result:

[0066] Ti(CN) content: 6%.

[0067] Viscosity: 2.5 Pa·s.

[0068] When TiO 2 When the content is 25%, the blast furnace permeability deteriorates to 30% (the percentage decrease relative to the standard permeability), the slag fluidity becomes worse, and serious poor permeability problems occur during the smelting process.

[0069] Example 1: Smelting of vanadium-titanium magnetite in an Ouye furnace

[0070] Purpose: To use Ouye furnace technology to replace the traditional blast furnace, and use the converter by-product diffused furnace gas as the blast air source.

[0071] Mineral composition: The main components and content of vanadium-titanium magnetite concentrate are TFe: 60%, TiO 2 :25%,V 2 O 5 :1.5%. The vanadium-titanium magnetite concentrate is prepared into pellets and lump ore, or self-fluxing pellets with a binary basicity of 1.0 to 1.3 are prepared, and the reduced material is obtained after being reduced by the coal gas produced by the gasification and melting furnace in the COREX pre-reduction shaft furnace. The temperature in the pre-reduction shaft furnace is maintained between 1000 and 1250°C.

[0072] Raw material particle size: After the high-temperature reducing material passes through the water-cooled heat exchanger at the discharge port and is cooled, the reducing material at a temperature of 200-500°C is sent to the crusher through a conveyor for crushing. The average particle size of the crushed reducing material is 10-30mm, and the temperature is 60-90°C. The crushed and cooled raw materials are ground to select vanadium-rich titanium materials and reduced iron, and the vanadium-rich titanium materials are sent to the wet process for vanadium and titanium extraction. The main components and contents of the vanadium-rich titanium materials after grinding are TFe 18%, TiO 2 45%, V 2 O 5 2.3%,Cr 2 O 3 1.2%. The composition of reduced iron is TFe 95%, TiO 2 3.9%, V 2 O 5 0.18%,Cr 2 O 3 1.1%.

[0073] Coal-iron mixing: The crushed and ground direct reduced iron particles are premixed with granular coal, with a coal-iron mass ratio of 0.8. The granular coal used is semi-coke, with an average particle size of 5-30mm, of which 10-25mm accounts for more than 90%. After mixing, they are put into the silo.

[0074] Smelting temperature: 1500℃.

[0075] Composition of byproduct gas: 20~35% CO, 30~40% CO 2 , the rest N 2 .

[0076] The furnace gas produced in the entire pre-reduction vertical furnace process is directly recovered and mixed with the vented furnace gas produced by the basic oxygen converter in the relay hot blast furnace. The average proportion of by-product vented furnace gas (volume fraction) is 45~60%.

[0077] The specific spraying method is as follows:

[0078] In the early stage of smelting, the thickness of the slag layer and the molten iron layer are relatively shallow. At this time, the slag-metal liquid level is about 900~1200mm, the ratio of the slag layer thickness to the molten iron layer thickness is 0.4~0.6, the side-blowing gun angle is about 65~85°, the gauge pressure is 0.1~0.25MPa, and the gas supply intensity is 0.8~1.6 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 55%, CO in the mixed injection gas is 31%, CO 2 37%, the remaining main components are CH 4 , H 2, the mixed gas temperature is 900℃, the slag and iron stirring is less intense, the reduction potential is high, it is in the initial reduction slag-making period, the slag phase gradually increases, and the molten iron layer gradually becomes thicker. However, due to the addition of a large amount of cold charge, the overall temperature of the furnace body and the molten pool is relatively low, about 1440℃;

[0079] In the middle stage of smelting, the thickness of slag layer and molten iron layer reaches 1500~1800mm, the ratio of slag layer thickness to molten iron layer thickness is 0.6~0.8, the side blowing gun angle is about 45~65°, the gauge pressure is 0.25~0.45MPa, and the gas supply intensity is 1.8~2.8 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 60%, CO in the mixed injection gas is 33%, CO 2 45%, the remaining main components are N 2 The mixed gas temperature is 900℃. At this time, the slag-iron interface reacts violently, a large number of metal elements are reduced, the thickness of the slag layer and the molten iron layer increases further, the side blowing stirring effect is intense, and the slag-iron interface layer forms a "spring-like" stirring vortex. The granular coal in the molten pool and the CO 2 The reaction generates CO gas, which overflows to the combustion zone above the molten pool and burns. The overall temperature of the furnace body and the molten pool rises to 1700℃.

[0080] At the end of smelting, the thickness of the slag layer and the molten iron reached 2000~2500mm, the ratio of the slag layer thickness to the molten iron layer thickness was 1.0~1.3, the side-blowing lance angle was about 25~45°, the gauge pressure was 0.15~0.25MPa, and the gas supply intensity was 1.0~2.0 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 50%, CO in the mixed injection gas is 28%, CO 2 44%, the remaining main components are N 2 , the mixed gas temperature is 900℃, at this time, the slag iron interface reaction activity is reduced, the injection intensity is reduced, and the CO 2 The ratio can reduce the intensity of the molten pool reaction and the furnace gas dust, promote the separation of the slag layer and the molten iron layer, and make full use of the physical heat of the furnace gas to supplement the heat of the furnace body, reduce the injection intensity of the fuel, and the overall temperature of the furnace body and the molten pool is still maintained at 1600~1800℃;

[0081] During the slag and iron discharge stage, the furnace temperature drops to about 1450℃ and the thickness of the slag and iron layer drops to below 900mm due to the heat taken away by the molten iron and slag. At this time, the amount of diffused furnace gas injection can be appropriately increased to maintain the temperature of the molten pool. The angle of the spray gun is adjusted between 15 and 30° and located above the molten pool. The proportion of converter diffused furnace gas in the injected mixed gas is about 45%, and the gas supply intensity is 1.3 to 2.3 m 3 / (t·min), CO 28% in the mixed gas, CO 239%, the remaining main components are N 2 The furnace gas temperature is 900℃, there is no stirring in the molten pool, the air pressure above the molten pool is higher than that without the side blowing spray gun, the slag and iron discharge speed is accelerated, the production efficiency is increased, and the temperature of the furnace body and the molten pool can be maintained at 1540℃.

[0082] result:

[0083] Ti(CN) content: 4%.

[0084] Viscosity: 1.2 Pa·s.

[0085] Although TiO 2 The content is still relatively high, but the use of Ouye furnace and the use of converter by-product gas as the blast air source has significantly improved the slag fluidity, and the permeability has only deteriorated to 10% (a percentage decrease relative to the standard permeability), and the permeability problem has been effectively alleviated.

[0086] Example 2: Increasing the usage of by-product gas in Ouye furnace

[0087] Purpose: On the basis of Example 1, the amount of by-product venting furnace gas used in the blast of the Ouye furnace is increased, and the partial pressure of CO in the mixed gas is higher, so as to further reduce the formation of titanium carbonitride (Ti(CN)).

[0088] Mineral composition: TFe: 60%, TiO 2 :25%,V 2 O 5 :1.5%.

[0089] Raw material particle size: 10~20mm.

[0090] Smelting temperature: 1480℃.

[0091] Furnace gas temperature: 1000℃.

[0092] Composition of by-product gas released from furnace:

[0093] Initial stage 36% CO, 34% CO 2 , the rest N 2 ;

[0094] Mid-term 35% CO, 43% CO 2 , the rest N 2 ;

[0095] 30% CO, 41% CO at the end of the period 2 , the rest N 2 ;

[0096] 29% CO, 38% CO during slag and iron discharge period 2 , the rest N2 ;

[0097] The average ratio of side-blowing by-product gas release is 60-75%, including 70% in the initial stage, 75% in the middle stage, 65% in the final stage, and 60% in the slag and iron discharge stage.

[0098] result:

[0099] Ti(CN) content: 2%.

[0100] Viscosity: 0.7 Pa·s.

[0101] The slag fluidity is further improved, the permeability deterioration is reduced to 5% (a percentage decrease relative to the standard permeability), and the permeability problem is more effectively alleviated.

[0102] Analysis and summary

[0103] In Comparative Example 1, when TiO 2 When the content is 25%, the Ti(CN) content in the slag reaches 6%, exceeding the critical value of 5%, causing the slag viscosity to increase to 2.5 Pa·s, which indicates that the slag fluidity is poor, which in turn causes the blast furnace permeability to deteriorate to 30%.

[0104] Example 1 shows that the Ouye furnace technology can significantly improve the slag fluidity, even in high TiO 2 When the Ti(CN) content in the slag is 0.1%, the Ti(CN) content in the slag is reduced to 4%, the slag viscosity is 1.2 Pa·s, and the permeability deterioration is only 10%.

[0105] Example 2 further improves the permeability, the Ti(CN) content in the slag is reduced to 2%, the slag viscosity is reduced to 0.7 Pa·s, and the permeability deterioration is reduced to 5%, which shows that the slag fluidity is very good and the permeability problem is almost solved.

Claims

1. A COREX method for smelting vanadium-titanium magnetite, characterized in that: The following steps are involved: Use granular coal instead of lump coal to enter the gasifier to increase the fluidity of granular coal in the molten pool and avoid accumulation; The vanadium-titanium magnetite direct reduced iron produced by the pre-reduction shaft furnace is put into the process of thermal crushing, heat recovery, grinding and premixing of granular coal before entering the gasifier, which increases the thermal utilization efficiency of the overall production process and reduces fuel consumption. Add a side-blowing lance to the molten pool. On the basis of circulating the pre-reduction vertical furnace gas to the gasifier, the pre-reduction vertical furnace vent gas and the converter by-product vent gas are used for direct blasting. (1) Pre-reduction: The vanadium-titanium magnetite concentrate is prepared into pellets and lumps, or self-fluxing pellets with a binary basicity in the range of 1.0-1.

3. The main components and contents of the vanadium-titanium magnetite concentrate are TFe 55-65%, TiO2 15-25%, V2O5 0.5-1.5%, Cr2O3 0.5-1.5%, and the rest are SiO2, CaO, Al2O3, and MgO. The concentrate is reduced by the furnace gas generated by the melt gasifier in the COREX pre-reduction shaft furnace to obtain a reducing material. The temperature in the pre-reduction shaft furnace is maintained between 1000 and 1250°C to ensure the effective reduction reaction. The main components and contents of the reducing material are TFe 60-75%, TiO2 15-25%, V2O5 0.5-1.5%, and Cr2O3 0.5-1.5%; (2) Hot crushing and grinding: After the high-temperature reducing material is cooled by heat exchange, the reducing material at a temperature of 200-500°C is crushed, and the crushed and cooled raw material is ground to select vanadium-containing titanium-rich material and reduced iron, and the vanadium-containing titanium-rich material is sent to the wet process for vanadium and titanium extraction; the composition and content of the vanadium-containing titanium-rich material after grinding are TFe 5-20%, TiO2 30-50%, V2O5 1-3%, Cr2O3 0.5-1.5%; the composition and content of the reduced iron are TFe 90-99%, TiO2 5-15%, V2O5 0.05-0.25%, Cr2O3 0.5-1.5%; (3) Raw material premixing: The crushed and ground direct reduced iron particles are premixed with granular coal. The granular coal used is non-coking coal or semi-coking coal, and the average particle size of the granular coal is 5-30 mm. After mixing, the mixture is stored in the silo for standby use; (4) Gasification and smelting reduction: Add the premixed raw materials into the molten gasifier, and maintain the molten pool temperature above 1450°C by spraying fuel and burning pure oxygen through a spray gun. Control the atmosphere in the furnace and add solvents to adjust the composition of the slag to maintain the TiO2 content of 5-10%, the titanium carbonitride content of 1-5%, and the viscosity of 0.1-1.5 Pa·s; TFe 95-99%, TiO2 0.1-1%, V2O5 0.1-0.5%, and Cr2O3 1-3% in the molten iron; (5) Side blowing of vented gas: The gas generated in the entire pre-reduction vertical furnace process is directly recovered and mixed with the vented gas generated by the alkaline oxygen converter in the relay hot blast furnace at a volume fraction of 20-80%. The gas is then sprayed into the slag-iron interface layer by adjusting the position of the side-blowing spray gun. The composition of the vented gas from the converter is 20-40% CO, 30-40% CO2, and the rest is N2. The temperature is 900-1100°C. The composition of the gas from the pre-reduction vertical furnace is 20-40% CO, 40-70% CO2, and the rest is CH4, SO2, and H2.

2. A COREX method for smelting vanadium-titanium magnetite according to claim 1, characterized in that: In the step (2), the average particle size of the crushed reducing material is 10-30 mm, and the temperature is 60-90° C.

3. A COREX method for smelting vanadium-titanium magnetite according to claim 1, characterized in that: In the step (5), at the initial stage of smelting, the thickness of the slag layer and the thickness of the molten iron layer are shallow. At this time, the slag-metal liquid level is 900-1200 mm, the ratio of the slag layer thickness to the molten iron layer thickness is 0.4-0.6, the side-blowing lance angle is 65-85°, the gauge pressure is 0.1-0.25 MPa, and the air supply intensity is 0.8-1.6 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 50~80%, the mixed injection gas composition is CO 30~40%, CO2 30~40%, and the other main components are CH4 and H2. The temperature of the mixed gas is 800~1000℃.

4. A COREX method for smelting vanadium-titanium magnetite according to claim 1, characterized in that: In the step (5), in the middle stage of smelting, the thickness of the slag layer and the thickness of the molten iron layer reach 1500-1800 mm, the ratio of the slag layer thickness to the molten iron layer thickness is 0.6-0.8, the side-blowing lance angle is 45-65°, the gauge pressure is 0.25-0.45 MPa, and the air supply intensity is 1.8-2.8 m 3 / (t·min), the proportion of converter gas in the mixed injection gas is 40~60%, the mixed injection gas composition is CO 25~35%, CO2 35~45%, and the other main component is N2, and the mixed gas temperature is 800~1000℃.

5. A COREX method for smelting vanadium-titanium magnetite according to claim 1, characterized in that: In the step (5), at the end of smelting, the thickness of the slag layer and the thickness of the molten iron reach 2000-2500 mm, the ratio of the slag layer thickness to the molten iron layer thickness is 1.0-1.3, the side-blowing lance angle is 25-45°, the gauge pressure is 0.15-0.25 MPa, and the air supply intensity is 1.0-2.0 m 3 / (t·min), the proportion of converter vent gas in the mixed injection gas is 20~50%, the mixed injection gas composition is CO 20~30%, CO2 40~50%, and the other main component is N2, and the mixed gas temperature is 800~1000℃.

6. A COREX method for smelting vanadium-titanium magnetite according to claim 1, characterized in that: In the step (5), during the slag and iron discharge stage, the furnace temperature drops to 1350-1450°C and the thickness of the slag and iron layer drops to below 900 mm due to the heat taken away by the molten iron and slag. At this time, the spray gun angle is adjusted to between 15° and 30° and is located above the molten pool. The proportion of converter gas in the sprayed mixed gas is 45-75%, and the gas supply intensity is 1.3-2.3 m 3 / (t·min), CO 25~35%, CO2 35~45% in the mixed gas, the remaining main component is N2, and the furnace gas temperature is 800~1000℃.

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