Method for smelting high-proportion sefstromite by using oxygen blast furnace

Abstract

A method for smelting high-proportion sefstromite by using an oxygen blast furnace. The method comprises the following steps: with pure oxygen blowing being used in a blast furnace, injecting pure oxygen, hot coal gas and pulverized coal from a tuyere, adding an iron charge and coke from the top of the furnace, wherein the volume percentage of N2 in coal gas at the top of the furnace is less than 25%, removing CO2 from the coal gas at the top of the furnace, and then recycling same. The method for smelting high-proportion sefstromite by using an oxygen blast furnace in the present invention can achieve such smelting that the proportion of sefstromite in the blast furnace is greater than 60%, the mass fraction of TiO2 in blast-furnace slag is greater than 15%, but smaller than 45%, and the emission of CO2 is reduced by 30% or more, and solves the problems of thick furnace slag, difficulties in slag-iron separation, blast wandering, high costs, high carbon emissions, etc., of conventional blast furnace smelting in the case of an increase in the proportion of sefstromite, thereby achieving higher utilization efficiency of vanadium-titanium resources, lower smelting costs and lower carbon emissions.

Description

Method for smelting high-proportion vanadium-titanium iron ore in oxygen blast furnace

[0001] The present application claims priority to the Chinese patent application No. 202410846712.9 filed on June 27, 2024, and entitled "Method for smelting high-proportion vanadium-titanium iron ore in oxygen blast furnace", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of metallurgy, in particular to a method for smelting high-proportion vanadium-titanium iron ore in oxygen blast furnace. BACKGROUND

[0003] The current mature ironmaking processes mainly include blast furnace ironmaking, smelting reduction (HIsmelt, COREX, Finex), direct reduction (gas-based direct reduction, coal-based direct reduction), etc., but these processes have their own advantages and disadvantages, mainly including:

[0004] (1) Blast furnace ironmaking process: mature technology, can realize single equipment annual capacity of more than one million tons, but its shortcomings are excessive dependence on high-quality metallurgical coke, need to build supporting coking, sintering, pelletizing, large system investment; difficult to operate, difficult to recover after abnormal and fluctuating furnace conditions; high cost, high carbon emission and high energy consumption, etc.; at the same time, the N2 content in the traditional blast furnace accounts for more than 40% of the total gas phase, which is easy to generate Ti(C,N) and form foaming slag in the furnace, which is not conducive to smooth production and index optimization;

[0005] (2) Smelting reduction: ①HIsmelt process has poor heat transfer effect, the molten iron temperature is only 1400-1450℃, and the flue gas volume is as high as 2700Nm 3 / t iron, the flue gas temperature reaches 1600℃, a large amount of physical heat is lost with the flue gas outside the furnace, resulting in high iron loss, high fuel consumption and high carbon emission; ②COREX, Finex molten iron [Si] content is high, coal gas generation is too large, and primary carbon consumption is high; ③The chemical energy utilization rate of carbon is not sufficient, part of the carbon elements escape with the coal gas in the form of CO, and the chemical energy cannot be further utilized;

[0006] (3) Direct reduction: ①Hydrogen-based shaft furnace has high requirements for ore quality; ②Coal-based direct reduction needs solid fuel, so the carbon consumption is high, and there is the same problem of high ore quality requirement for gas-based shaft furnace.

[0007] Vanadium-titanium magnetite is a composite ore with multiple metal elements, mainly including iron, vanadium and titanium. Vanadium-titanium magnetite is the main raw material for producing vanadium and the main mineral raw material for extracting Ti and Fe. At the same time, vanadium-titanium magnetite is also one of the most difficult smelting minerals recognized by the world, and its comprehensive utilization is difficult.

[0008] The main smelting process of vanadium-titanium-iron ore is blast furnace smelting method, and there are two technical problems in smelting vanadium-titanium-iron ore by blast furnace:

[0009] Firstly, the proportion of vanadium-titanium-iron ore is difficult to increase. In the prior art, when the proportion of vanadium-titanium-iron ore in blast furnace (the proportion of vanadium-titanium-iron ore in blast furnace in the present application refers to the ratio of the amount of vanadium-titanium-iron ore in the iron-containing raw material used for producing sinter and pellet to the sum of the total amount of iron-containing raw material used for producing sinter and pellet and the amount of iron-containing lump ore used for blast furnace) increases, the content of slag (TiO2) in blast furnace increases, Ti(C, N), TiC and TiN are produced, which causes the phenomena of sticky slag, difficult separation of slag and iron, foaming slag and the like; meanwhile, if the proportion of vanadium-titanium-iron ore in blast furnace is increased by increasing the proportion of vanadium-titanium-iron ore in sintering raw material, with the increase of the content of (TiO2) in sinter, a series of technical problems such as the decrease of sinter drum strength, the increase of reduction pulverization, the deterioration of blast furnace smoothness, the increase of sinter return rate, the increase of fuel cost per ton of iron and the like are caused.

[0010] Secondly, the carbon emission and energy consumption of the process are high. The proportion of CO in blast furnace top gas is about 20-30%, and the chemical energy of this part of CO cannot be effectively utilized in the prior art, but is utilized by combustion power generation, and the thermal energy conversion efficiency of blast furnace gas combustion power generation is less than 40%, so the system energy consumption and carbon emission are high. SUMMARY

[0011] The purpose of the present application is to provide a method for smelting high-proportion vanadium-titanium-iron ore by oxygen blast furnace, which is used to solve the technical problems of the prior art that the proportion of vanadium-titanium-iron ore is difficult to increase and the carbon emission and cost of the process are high.

[0012] In order to achieve the above purpose, one embodiment of the present application provides a method for smelting high-proportion vanadium-titanium-iron ore by oxygen blast furnace, which comprises the following steps:

[0013] The blast furnace adopts pure oxygen injection, and pure oxygen, hot coal gas and coal powder are injected into the tuyere; iron materials and coke are added from the top of the blast furnace; wherein the volume percentage of N2 in the top gas is <25%; the top gas is recycled after removing CO2;

[0014] The iron material is pellet or the iron material is at least one of the following materials: sinter and lump ore;

[0015] The TiO2 content in the pellet is 3%-13%, the iron raw material used for producing the pellet is vanadium-titanium-iron ore, and the proportion of the pellet in the iron material charged into the blast furnace is >30%; the TiO2 content in the sinter is <5%;

[0016] The mass fraction of TiO2 in the blast furnace slag generated by smelting is >15% and <45%, the proportion of vanadium-titanium-iron ore in blast furnace is >60%, and the CO2 emission of blast furnace is reduced by 30%.

[0017] In one preferred embodiment of the present application, the hot coal gas is the gas heated in a coal gas heating furnace, and the sources of the gas in the coal gas heating furnace include coke oven gas, steam and purified coal gas, wherein the flow rate of the coke oven gas fed into the coal gas heating furnace is 20 Nm 3 / t-200 Nm 3 / t, the ratio of the steam to the coke oven gas in terms of the amount of substance fed into the heating furnace is 0.10-0.30:1.

[0018] In one preferred embodiment of the present application, in the blast furnace smelting process,

[0019] When the mass fraction of TiO2 in the blast furnace slag is >15% and ≤18%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is ≥0.4% and ≤0.8%;

[0020] When the mass fraction of TiO2 in the blast furnace slag is >18% and ≤20%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is ≥0.3% and ≤0.7%;

[0021] When the mass fraction of TiO2 in the blast furnace slag is >20% and ≤25%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is ≥0.10% and ≤0.6%;

[0022] When the mass fraction of TiO2 in the blast furnace slag is >25%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is ≥0.05% and ≤0.55%.

[0023] In one preferred embodiment of the present application, the mass ratio of the blast furnace iron charge to the coke is 5.5-7.5:1, and the mass ratio of the blast furnace iron charge to the coal powder is 15-40:1; the blast furnace fuel ratio in the blast furnace smelting is <400 kg / t, and the coke ratio is <300 kg / t.

[0024] In one preferred embodiment of the present application, the distribution coefficient of the vanadium element in the molten iron and the slag in the blast furnace smelting process is [V] / (V2O5)>1.1.

[0025] In one preferred embodiment of the present application, the flow rate of the hot coal gas injected is 700 Nm 3 / t-1280 Nm 3 / t, the flow rate of the pure oxygen injected is 145 Nm 3 / t-245 Nm 3 / t.

[0026] In one preferred embodiment of the present application, the charging method of iron materials and coke is as follows: taking a horizontal cross section of the blast furnace at the blast furnace charging level, the cross section is equally divided into 11 rings, and the rings are numbered from the inner ring to the outer ring; the distribution of the materials is as follows: 60%-80% of the coke is distributed in the 9th ring to the 11th ring and the 1st ring to the 5th ring, 20%-40% of the coke is distributed in the 6th ring to the 8th ring, 70%-90% of the iron materials is distributed in the 4th ring to the 10th ring, and 10%-30% of the iron materials is distributed in the 1st ring to the 3rd ring and the 11th ring.

[0027] In summary, the present application has the following advantages:

[0028] 1. The problem of sticky and foamy slag in the smelting of vanadium-titanium iron ore is solved. The volume percentage of N2 in the top gas in the smelting method of the present application is less than 25%, which is significantly reduced compared with the volume percentage of N2 in the traditional blast furnace gas, which is 45%-60%. Compared with the traditional blast furnace, the partial pressure of N2 is reduced, the partial pressure of CO is increased, and the furnace temperature is reasonably controlled, which effectively inhibits the generation of Ti(C,N), prevents the sticky and difficult separation of slag and iron from the source, controls the foamy slag, and further solves one of the problems affecting the increase of the proportion of vanadium-titanium iron ore in the blast furnace.

[0029] 2. The problem of poor metallurgical properties of vanadium-titanium sinter is solved. By optimizing the ore blending structure, controlling the TiO2 content in the sinter to be less than 5%, and adding as much vanadium-titanium iron ore as possible to the pellet blending, the present application solves a series of technical problems such as the decrease of the drum strength of vanadium-titanium sinter, the high reduction pulverization, the high return rate of the blast furnace, the poor blast furnace operation, the poor furnace condition, the increase of the fuel cost per ton of sinter, and further solves another problem affecting the increase of the proportion of vanadium-titanium iron ore in the blast furnace.

[0030] 3. The ore blending cost of the present application is significantly reduced. By optimizing the ore blending structure, the present application realizes the proportion of vanadium-titanium iron ore of 60%-100% and the comprehensive titanium load of the charging raw materials of 110-220 kg / t. The average price difference between domestic vanadium-titanium iron ore and ordinary iron ore is 200 yuan / ton. According to the proportion of vanadium-titanium iron ore of 60% and the iron ore consumption of 1.6 t / t, the ore blending cost of each ton of molten iron can be reduced by 192 yuan.

[0031] 4. The mass percentage of TiO2 in the slag is significantly improved. When the mass percentage of TiO2 in the vanadium-titanium iron ore is less than 12%, the mass percentage of TiO2 in the blast furnace slag is less than 23% in the traditional blast furnace smelting of vanadium-titanium iron ore. The mass percentage of TiO2 in the blast furnace slag can be in the range of 15-45% by the present application, wherein when the mass percentage of TiO2 in the vanadium-titanium iron ore reaches 8%, the mass percentage of TiO2 in the blast furnace slag can reach 27%; when the mass percentage of TiO2 in the vanadium-titanium iron ore reaches 10%, the mass percentage of TiO2 in the blast furnace slag can reach 30%; and when the mass percentage of TiO2 in the vanadium-titanium iron ore is greater than 12%, the mass percentage of TiO2 in the blast furnace slag can reach 40%. The increase of the mass percentage of TiO2 in the blast furnace slag greatly improves the utilization value of the slag.

[0032] 5. The fuel cost of the blast furnace is reduced, and the CO2 emission is reduced. The present application uses pure oxygen injection, and the CO2 in the top gas is removed and then heated and injected back into the furnace. This increases the amount of reducing gas CO in the furnace and reduces the amount of solid fuel that needs to be burned at the tuyere (the purpose of burning solid fuel at the tuyere is to provide heat and provide CO reducing gas). The consumption of solid fuel is reduced by 30-40%, and the comprehensive cost of fuel and power is reduced by about 50-100 yuan / ton of molten iron (different regions have different prices, resulting in differences in cost reduction data). BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a smelting process flow diagram of an embodiment of the present application.

[0034] Among them, 1-blast furnace, 2-gas purification facility, 3-gas pipe network, 4-gas heating furnace. DETAILED DESCRIPTION

[0035] The present application provides a method for smelting high-proportion vanadium-titanium iron ore by oxygen blast furnace, which involves a device including a blast furnace 1, a gas purification facility 2, and a gas heating furnace 4. The smelting method includes the following steps: adding blast furnace iron material and coke into the blast furnace 1, using pure oxygen injection at the blast furnace 1, injecting pure oxygen, hot coal gas, and coal powder at the tuyere for smelting, generating liquid slag and molten iron, and discharging the slag and molten iron out of the furnace through a slag-iron port.

[0036] The specific process flow and process parameters are as follows:

[0037] (1) Process flow

[0038] As shown in Figure 1, the process flow of smelting high-proportion vanadium-titanium iron ore by oxygen blast furnace is as follows:

[0039] ① hot coal gas is blown into the blast furnace 1 through the blast pipe of the air supply branch pipe, and then through the large set, the second set and the small set of the tuyere in sequence; the pulverized coal is blown into the blast furnace 1 through the coal injection gun located at the blast pipe of the air supply branch pipe, and then through the large set, the second set and the small set of the tuyere in sequence; and the oxygen is blown into the blast furnace 1 from the small set of the tuyere;

[0040] ② the coke and iron materials of the blast furnace are loaded into the blast furnace from the top of the blast furnace through the loading equipment, wherein the iron material is the pellet or the iron material is the pellet and at least one of the following materials: sintered ore and lump ore; the blast furnace fuel includes but is not limited to pulverized coal and coke;

[0041] ③ the coal gas generated by the combustion of the oxygen and the fuel in front of the tuyere, the hot coal gas injected through the small set of the tuyere and the coal gas generated by the chemical reaction of the hearth jointly form the bosh gas, the bosh gas generates the liquid slag and molten iron through the physical and chemical reaction with the descending iron material in the upward process, and the slag and molten iron are discharged out of the furnace from the slag-iron hole;

[0042] ④ the top gas generated by the reaction in the furnace is discharged from the top gas pipeline, the top gas is de-dusted, de-CO2 and de-H2O through the gas purification facility 2 to become purified gas, the purified gas reaches the gas pipeline network 3, part of the purified gas is transmitted to other users for use, and the other part of the purified gas is mixed with the coke oven gas and water vapor to be delivered into the gas heating furnace 4, and after being heated, becomes hot gas. The above entire smelting process realizes carbon cycle.

[0043] (2) Material structure and slagging system

[0044] Due to the poor sintering characteristics of vanadium-titanium iron ore, the sinter prepared therefrom has poor quality, mainly in the aspects of low falling strength, low drum strength, low yield, and serious low-temperature reduction pulverization, etc. Therefore, the industrial application of vanadium-titanium iron ore is limited, and when the proportion of vanadium-titanium iron ore in the sinter is too large, a series of problems such as high return ore rate of blast furnace, rising fuel cost per ton of iron, poor blast furnace permeability and unstable furnace condition, etc. will be caused. In order to increase the proportion of vanadium-titanium iron ore into the blast furnace, while controlling the cost and stabilizing the furnace condition, the vanadium-titanium iron ore is preferentially added in the pellet burden, and the surplus part is added in the sinter burden in a small amount, and the TiO2 content in the sinter is controlled to be <5%. Specifically:

[0045] ① In the process of pellet burdening, the proportion of vanadium-titanium iron ore in the iron material is selected as the maximum value, for example, 100% vanadium-titanium iron ore is used for balling, and no other iron material except vanadium-titanium iron ore is added, and the TiO2 content in the pellet is determined by the TiO2 content in the vanadium-titanium iron ore, and according to the present situation of vanadium-titanium iron ore resources at home and abroad, the TiO2 content in the pellet is in the range of 3%-13%;

[0046] ② In the process of blast furnace burdening, the proportion of vanadium-titanium iron ore in blast furnace is increased by increasing the proportion of pellet (the proportion of pellet refers to the mass proportion of pellet in the iron charge of blast furnace). The optimal proportion of pellet in blast furnace is 100%. When the production capacity of pellet production line is insufficient, the insufficient part can be replaced by sinter. The minimum production capacity of pellet production line should ensure that the proportion of pellet in blast furnace is greater than 30%.

[0047] ③ When the proportion of pellet in blast furnace has reached the upper limit, but the proportion of vanadium-titanium iron ore in blast furnace still needs to be further increased, for example, when the production capacity of pellet production line can only ensure that the maximum proportion of pellet in blast furnace is 30%, but the desired proportion of vanadium-titanium iron ore in blast furnace is greater than 60%, vanadium-titanium iron ore is added in sinter.

[0048] ④ In the process of sintering burdening, the proportion of vanadium-titanium iron ore should not be too large to reduce the negative impact of TiO2 on sinter quality and blast furnace production. The TiO2 content in sintered product should be controlled to be less than 5%.

[0049] According to the above method of burdening, when the proportion of pellet is not limited, i.e. full pellet proportion = 100%, the proportion of vanadium-titanium iron ore in blast furnace can reach 100%, and the mass fraction of TiO2 in blast furnace slag is 15% to 45%. When the proportion of pellet is limited, it will affect the increase of the mass fraction of TiO2 in blast furnace slag and the increase of the proportion of vanadium-titanium iron ore in blast furnace. Specifically, when 30% < pellet proportion < 100%, for low-titanium vanadium-titanium iron ore with TiO2 content in ore < 5.0%, the proportion of vanadium-titanium ore can reach 100%, and the mass fraction of TiO2 in blast furnace slag is 15% to 22%; when 30% < pellet proportion < 100%, for medium-titanium vanadium-titanium iron ore with 5% ≤ TiO2 content in ore < 8%, the proportion of vanadium-titanium iron ore in blast furnace can reach 100%, and the mass fraction of TiO2 in blast furnace slag is 16% to 26%; when 30% < pellet proportion < 100%, for high-titanium vanadium-titanium iron ore with TiO2 content in ore ≥ 8%, the proportion of vanadium-titanium iron ore in blast furnace is > 60%, and the mass fraction of TiO2 in blast furnace slag is 23% to 45%.

[0050] The above summary is: the mass fraction of TiO2 in blast furnace slag can be 15% to 45%, and the proportion of vanadium-titanium iron ore in blast furnace is > 60%.

[0051] Through the above burdening, the proportion of vanadium-titanium iron ore in blast furnace is 60-100%. For vanadium-titanium iron ore with TiO2 content in ore > 8%, by adjusting the proportion of vanadium-titanium pellet to more than 50%, the titanium load of the iron charge can be 110-220 kg / t.

[0052] (3) Thermal system

[0053] Furnace temperature is the basis of stable production of blast furnace, and is also an important index to judge the furnace condition. For vanadium-titanium iron ore smelting, too low furnace temperature will cause the softening zone in the furnace to become thin, uneven distribution of initial coal gas flow, and local coal gas pipeline in the material column, uneven feeding, partial material, and material collapse, etc. Too high furnace temperature will cause a large amount of Ti(C, N) to be generated, sticky and foamy slag, difficulty in separating slag and iron, furnace lining sticking, blast furnace pressure difference rising, and abnormal production, etc. Through simulation analysis of the temperature field distribution in the furnace, and calculation of the thermodynamic and kinetic conditions of Ti(C, N) generation, it is concluded that, in order to ensure the smooth operation of the furnace, the furnace temperature control target range needs to be determined according to the mass fraction of TiO2 in the blast furnace slag.

[0054] On the other hand, for vanadium-titanium iron ore smelting, it is necessary to reduce and dissolve as much vanadium element as possible in the molten iron to improve the utilization rate of vanadium resources. The furnace temperature is an important factor to determine the distribution coefficient Lv of vanadium element in the molten iron and the slag. Maintaining a suitable furnace temperature can achieve a better vanadium distribution coefficient Lv, wherein the vanadium distribution coefficient Lv = [V] / (V2O5), [V] refers to the mass percentage of vanadium element in the molten iron, and (V2O5) refers to the mass percentage of V2O5 in the slag.

[0055] The present application adjusts the furnace temperature by adjusting the mass ratio of iron charge and fuel, the amount of coal injection, and the hot coal gas temperature, and detects and feeds back the furnace temperature level through the mass fraction of [Si] and [Ti] in the molten iron. Specifically:

[0056] ①Reasonable furnace temperature control range

[0057] When 15% < mass fraction of TiO2 in the blast furnace slag ≤ 18%, 0.4% ≤ the sum of the mass fractions of [Si] and [Ti] in the molten iron ≤ 0.8% should be controlled;

[0058] When 18% < mass fraction of TiO2 in the blast furnace slag ≤ 20%, 0.3% ≤ the sum of the mass fractions of [Si] and [Ti] in the molten iron ≤ 0.7% should be controlled;

[0059] When 20% < mass fraction of TiO2 in the blast furnace slag ≤ 25%, 0.10% ≤ the sum of the mass fractions of [Si] and [Ti] in the molten iron ≤ 0.6% should be controlled;

[0060] When the mass fraction of TiO2 in the blast furnace slag > 25%, 0.05% ≤ the sum of the mass fractions of [Si] and [Ti] in the molten iron ≤ 0.55% should be controlled.

[0061] ②Reasonable ore-coke ratio and ore-coal ratio

[0062] The blast furnace iron material and coke are charged from the top of the furnace in a mass ratio of 5.5-7.5:1 of iron material to coke, and the iron material and coal powder are charged and injected into the furnace in a mass ratio of 15-40:1 of iron material to coal powder.

[0063] When the furnace temperature is temporarily low, the amount of coal injection into the blast furnace can be adjusted so that the ratio of iron material to coal powder is reduced; when the furnace temperature is temporarily high, the amount of coal injection into the blast furnace can be adjusted so that the ratio of iron material to coal powder is increased.

[0064] When the furnace temperature is long-term low, the amount of coke charged into the blast furnace can be adjusted so that the ratio of iron material to coke is reduced; when the furnace temperature is long-term high, the amount of coke charged into the blast furnace can be adjusted so that the ratio of iron material to coke is increased.

[0065] According to the above parameter control, a reasonable charging system and injection parameters are matched, so that the fuel ratio of the blast furnace is <400 kg / t, the coke ratio is <300 kg / t, and the typical value range is coal ratio 50-100 kg / t, coke ratio 260-280 kg / t. The distribution coefficient of vanadium element in molten iron and slag [V] / (V2O5) is >1.1.

[0066] (4) Charging system

[0067] The charging system of the blast furnace plays an important role in the gas flow distribution of the blast furnace, the energy utilization rate of the blast furnace and the smooth operation of the furnace. The charging of the blast furnace is realized by the charging equipment at the top of the furnace. At present, there are two kinds of charging equipment, namely the minute top of the furnace and the top of the furnace without the bell. The parameters of the charging equipment of different volumes of the blast furnace are also very different. For example, for the same top of the furnace without the bell, the falling points of the furnace charge in the furnace are different corresponding to different distribution angles. Therefore, a unified method is needed to regulate the distribution of the furnace charge in the furnace. The present application focuses on the top of the furnace without the bell and gives a reasonable distribution method.

[0068] The specific distribution method is as follows: at the height of the blast furnace charge surface, take the horizontal direction of the cross section of the blast furnace, divide the cross section into 11 equal area rings, and number them from the inner ring to the outer ring as 1 ring, 2 ring, 3 ring, 4 ring, 5 ring, 6 ring, 7 ring, 8 ring, 9 ring, 10 ring and 11 ring. The charging system is: 60%-80% of the coke is distributed in the 9th-11th ring and the 1st-5th ring, 20%-40% of the coke is distributed in the 6th-8th ring, 70%-90% of the iron material is distributed in the 4th-10th ring, and 10%-30% of the iron material is distributed in the 1st-3rd ring and the 11th ring.

[0069] Because of the vanadium-titanium sinter and pellet, the reduction process in the blast furnace is more serious than ordinary ore powder, therefore, in order to make the oxygen blast furnace have good permeability, the strength of the iron ore into the furnace is required to be higher, generally the compressive strength of the pellet is required to be greater than or equal to 2500N, which increases the processing cost, energy consumption and carbon emission of raw materials. The present application adopts the above distribution system, so that even under the condition of lower iron ore strength, the blast furnace can still obtain suitable permeability, smooth discharge and higher iron yield after the proportion of vanadium-titanium ore is increased. Through test verification, by adopting the above distribution system, the compressive strength of the pellet can be reduced to 1800N at the lowest, without affecting the normal production and technical and economic indexes of the blast furnace.

[0070] (5) The tuyere injection parameters

[0071] In the production of the blast furnace, the combustion reaction (reaction product CO) of carbon in front of the tuyere is the main source of heat and reducing agent of the blast furnace. The substances injected into the tuyere of the traditional blast furnace include hot air, oxygen and coal powder. Under the condition of releasing the same heat and CO, the traditional blast furnace process brings a large amount of N2, and this part of N2 does not participate in the reduction reaction of iron oxides, but plays the role of increasing the blast kinetic energy, stirring and activating the hearth.

[0072] Especially in the smelting process of vanadium-titanium ore, the generation of Ti(C, N) needs to be inhibited, and the requirement for blast kinetic energy is more stringent. Insufficient blast kinetic energy will cause local inactivity of the hearth, and the residence time of Ti elements in the furnace increases, which increases the generation of Ti(C, N), and further makes the slag viscous and difficult to separate from the iron. The amount of coal gas in the bosh is an important parameter affecting the blast kinetic energy and the activity of the hearth.

[0073] The method for smelting high-proportion vanadium-titanium iron ore in the oxygen blast furnace of the present application is different from the injection process flow of the traditional blast furnace. In the present application, the substances injected into the tuyere of the blast furnace include hot coal gas, oxygen and coal powder. Only a small amount of carbon needs to be burned to meet the heat and reducing agent requirements in the furnace. However, in order to meet the reasonable requirements for blast kinetic energy and hearth activity, it is necessary to control the reasonable amount of bosh coal gas. The production test shows that the amount of bosh coal gas in the oxygen blast furnace smelting high-proportion vanadium-titanium iron ore is controlled in the range of 1200Nm 3 / t-1750Nm 3 / t, which is more appropriate. According to the amount of bosh coal gas and the amount of coke needed to be burned in the furnace, the tuyere injection parameters are further determined as follows:

[0074] The amount of hot coal gas injected into the furnace in the present application is 700Nm 3 / t-1280Nm 3 / t, and the amount of oxygen injected into the furnace is 145Nm 3 / t-245Nm 3The hot coal gas is the gas heated by the coal gas heating furnace, the coal gas heating furnace includes coke oven gas, water vapor and purified coal gas, the input amount of the coke oven gas delivered into the coal gas heating furnace is 20 Nm 3 / t-200 Nm 3 / t, the ratio of the water vapor to the coke oven gas in the coal gas heating furnace is 0.10-0.30 mol:1 mol.

[0075] The present application delivers a part of the coke oven gas, water vapor and purified coal gas into the coal gas heating furnace, the purpose of adding the water vapor into the mixed gas is to make the water vapor and the coke oven gas have a series of reforming reactions, so that the complex hydrocarbon is reformed to generate H2 and CO, for example, CH4+H2O→CO+H2, C2H2+H2O→CO+H2. The mixing ratio of the water vapor is determined according to the composition of the coke oven gas, the reaction thermodynamics and kinetics in the heating furnace, and the best value range is that the ratio of the water vapor to the coke oven gas in the coal gas heating furnace is 0.10-0.30:1.

[0076] According to the above blowing parameter control, the blast furnace top gas after removing the dust, CO2 and H2O becomes the purified coal gas, the amount of the purified coal gas is greater than the required amount of the purified coal gas of the coal gas heating furnace, and the surplus part is used by the external users, that is, the coal gas semi-sealed recycling is realized.

[0077] Since the compressed air used for blowing the pulverized coal contains about 79% N2, the top equipment needs to be sealed and purged by N2, and the coke oven gas also contains 6%-10% N2. Therefore, the present application cannot be realized in a zero nitrogen environment. After the coal gas removes the dust, CO2 and H2O, the N2 is easily enriched in the recycling process. However, according to the above blowing parameter control, through the coal gas semi-sealed recycling, that is, a part of the N2 enriched purified coal gas is exported to be used by other users, and a part of the coke oven gas with low N2 content is reformed and heated to be injected into the furnace, so that the N2 volume percentage in the blast furnace top gas is less than 25% after the system is balanced, and the more optimal range is 7-15%, which is significantly lower than the N2 volume percentage 45%-60% in the traditional blast furnace gas.

[0078] The role of supplementing the coke oven gas reforming gas in the heating furnace has two points: one is to increase the blast kinetic energy and ensure the activity of the hearth, and the other is to dilute the N2 content of the furnace gas.

[0079] The thermodynamic calculation shows that the generation of Ti(C, N) in the blast furnace smelting vanadium-titanium iron ore has a close relationship with the N2 content, the starting temperatures of reactions (1) and (2) are 1136℃ and 1108℃ respectively, that is, TiN is generated slightly earlier than TiC, and in fact, pure TiN and TiC rarely exist in the blast furnace, and the complex solid solution promotes the generation of each other.

[0080] TiO2+ 3C = TiC + 2CO ΔG θ = 524130 - 333.55T (J / mol) (1)

[0081] Critical for precipitating TiC is:

[0082] Critical for precipitating TiN is:

[0083] Critical for precipitating Ti(C,N) is:

[0084] Because of the high N2 content in the traditional blast furnace, when the mass ratio of slag (TiO2) reaches 23%, the Ti(C,N) generated in the furnace will make the blast furnace unable to produce normally. In the present application, the N2 partial pressure is reduced and the CO partial pressure is increased, and at the same time, the sum of the mass fractions of [Si] and [Ti] in the molten iron is monitored to control the furnace temperature T, which effectively inhibits the generation of Ti(C,N). Tests show that when the volume fraction of N2 in the top gas is controlled to be < 25%, the slag-iron separation effect and the fluidity of the slag are still good when the mass ratio of slag (TiO2) reaches 45%, and the blast furnace can still produce stably and normally.

[0085] In addition, in the smelting method of the present application, a part of the coke oven gas, water vapor and purified gas are mixed and delivered into a gas heating furnace, and after heating, become hot gas, and the temperature range of the hot gas is 900-2300 DEG C. Within the range of 900-2300 DEG C, the higher the temperature of the hot gas, the more conducive to reducing the solid fuel ratio and carbon emissions of the blast furnace, wherein the solid fuel ratio includes coal ratio and coke ratio. At the same time, the gas heating furnace can use electric heating method, or hot blast furnace heating method, or plasma gas heating method, and the ultimate goal is to obtain high-temperature gas at low cost, and according to the current technical level, different heating equipment can obtain different hot gas temperatures. The most economical method is to recommend the hot blast furnace heating method to obtain 1250-1280 DEG C gas temperature.

[0086] Example 1: High-titanium slag smelting of high-titanium vanadium-titanium iron ore resources

[0087] The composition of the high-titanium vanadium-titanium iron ore in a certain place is shown in Table 1:

[0088] Table 1: Composition table of vanadium-titanium iron ore in Example 1

[0089] The vanadium-titanium iron ore is used to produce the pellet, and no other iron-containing raw material is added in the ore blending process, and the composition of the produced pellet is shown in Table 2.

[0090] Table 2: Composition table of the pellet produced by the vanadium-titanium iron ore in Example 1

[0091] The ratio of the blast furnace pellet in the blast furnace iron material is 100% pellet, no sinter and lump ore is added, and the ratio of the blast furnace vanadium-titanium iron ore is 100%. The composition of the generated blast furnace slag is shown in Table 3.

[0092] Table 3: Composition table of the blast furnace slag produced in Example 1

[0093] According to the method for smelting high-proportion vanadium-titanium iron ore in the oxygen blast furnace according to the application (including the heat system, the charging method and the tuyere gas injection parameter), the actual obtained results are that the [V] content in the molten iron is 0.536%, the coke ratio is 260 kg / t, the coal ratio is 100 kg / t, the distribution coefficient of the vanadium element in the molten iron and the slag [V] / (V2O5) = 1.35 > 1.3, the titanium load of the comprehensive raw material into the furnace is 180 kg / t, the slag (TiO2) content reaches 31.25%, which is much higher than the current international leading level (the titanium load into the furnace is 110-130 kg / t, and the slag TiO2 content is 22-23%). Compared with the traditional blast furnace, the fuel and power cost used in the smelting method of the application is reduced by 57 yuan / t of iron, and further, since the price of vanadium-titanium iron ore is lower than that of ordinary iron ore, the ore blending cost of the application is reduced by 420 yuan / t, and the CO2 physical emission is reduced by 33.3%.

[0094] Example 2: Smelting of titanium slag in high-titanium vanadium-titanium iron ore resources

[0095] The composition of the high-titanium vanadium-titanium iron ore in a certain place is shown in Table 4.

[0096] Table 4: Composition table of the vanadium-titanium iron ore in Example 2

[0097] The vanadium-titanium iron ore is used to produce the pellet, and no other iron-containing raw material is added in the ore blending process, and the composition of the produced pellet is shown in Table 5:

[0098] Table 5: Composition table of the pellet produced by the vanadium-titanium iron ore in Example 2

[0099] Due to insufficient production of the pellet, but in order to obtain good sintering performance of the sinter, for the vanadium-titanium-iron ore with TiO2 content > 8%, it is recommended that the proportion of the pellet in the blast furnace iron charge > 50%, for example, the blast furnace charging ore ratio is 60% pellet and 40% sinter, without adding lump ore. The TiO2 content of the sinter is controlled to be < 3.5 to obtain good sintering performance. Therefore, the vanadium-titanium-iron ore is preferentially used for pellet production, and the remaining part is used for sinter production. The iron raw material for sinter production is partly vanadium-titanium-iron ore and partly other iron ore. Since the TiO2 content of the vanadium-titanium sinter is controlled to be < 3.5, the metallurgical performance of the vanadium-titanium sinter can be greatly improved, and special control of the MgO content in the sinter is not required, thereby saving the amount of high-MgO flux added in the sinter production process, and further reducing the production cost. The composition of the sinter is shown in Table 6, and the proportion of the vanadium-titanium-iron ore in the blast furnace is > 75%.

[0100] Table 6: Sinter composition table of Example 2

[0101] Compared with the traditional smelting, after the implementation, the sinter drum strength is increased from an average of 72.0% to an average of 77.3%, and the sinter drum strength after the implementation is > 76%; the sinter low-temperature reduction differentiation rate is improved from an average of 55% to an average of 26.1%, and the sinter low-temperature reduction pulverization rate after the implementation is < 30%.

[0102] The composition of the generated blast furnace slag is shown in Table 7. It is verified by tests that in order to improve the fluidity of the slag, the high-proportion vanadium-titanium-iron ore smelting needs to control the slag basicity R2 < 1.12.

[0103] Table 7: Sinter composition table of Example 2

[0104] According to the oxygen blast furnace smelting method of the high-proportion vanadium-titanium-iron ore of the present application (including the heat system, the charging method and the tuyere gas blowing parameters), the actual obtained results are: the [V] content in the molten iron is 0.313%, the coke ratio is 270 kg / t, the coal ratio is 100 kg / t, the distribution coefficient of the vanadium element in the molten iron and the slag [V] / (V2O5) = 1.38 > 1.3, the titanium load of the charging comprehensive raw material is 135 kg / t, and the slag (TiO2) content reaches 23.57%, which is superior to the current international leading level. Compared with the traditional blast furnace, the fuel and power cost used in the smelting method of the present application is reduced by 57 yuan / ton of iron, further, due to the price of the vanadium-titanium-iron ore being lower than that of the ordinary iron ore, the ore matching cost is reduced by 13 yuan / ton of iron, and the CO2 physical emission is reduced by 31.5%.

[0105] Example 3: Titanium slag smelting in low-titanium vanadium-titanium-iron ore resources

[0106] The composition of the low-titanium vanadium-titanium iron ore in a certain place is shown in Table 8:

[0107] Table 8: Composition table of low-titanium vanadium-titanium iron ore in Example 3

[0108] The above vanadium-titanium iron ore is used to produce pellets, and no other iron-containing raw materials are added in the ore blending process. Flux and binder are added in the ore blending process, and the composition of the produced pellets is shown in Table 9:

[0109] Table 9: Composition table of pellets produced by vanadium-titanium iron ore in Example 3

[0110] The proportion of blast furnace pellets in the blast furnace iron charge is 100%, without adding sinter and lump ore, and the proportion of vanadium-titanium iron ore in the blast furnace is 100%. The composition of the generated blast furnace slag is shown in Table 10:

[0111] Table 10: Composition table of blast furnace slag produced in Example 3

[0112] According to the method of the present application for smelting high-proportion vanadium-titanium iron ore in an oxygen blast furnace (including the heat schedule, charging method and tuyere gas injection parameters), the actual results obtained are: the [V] content in the molten iron is 0.767%, the coke ratio is 260 kg / t, the coal ratio is 90 kg / t, and the distribution coefficient of vanadium element in the molten iron and slag [V] / (V2O5) = 1.51 > 1.3. Compared with the traditional blast furnace, the fuel and power costs used in the smelting method of the present application are reduced by 53 yuan / ton of iron, and further, due to the lower price of vanadium-titanium iron ore than ordinary iron ore, the ore blending cost of the present application is reduced by 310 yuan / ton, and CO2 physical emission is reduced by 35.2%.

[0113] Example 4: Smelting of titanium slag in low-titanium vanadium-titanium iron ore resources

[0114] The composition of the low-titanium vanadium-titanium iron ore in a certain place is shown in Table 11:

[0115] Table 11: Composition table of low-titanium vanadium-titanium iron ore in Example 4

[0116] Due to insufficient production of pellet production line, the blast furnace charging ore ratio is 55% acidic pellets and 45% alkaline sinter, without adding lump ore. The above vanadium-titanium iron ore is used to produce pellets, and no other iron-containing raw materials and flux are added in the pellet blending process. Binder is added in the pellet blending process, and the composition of the produced pellets is shown in Table 12:

[0117] Table 12: Composition table of pellets produced by vanadium-titanium iron ore in Example 4

[0118] Vanadium titano-magnetite is preferentially used for pellet production, the rest is used for sinter production, the Ti02 content of sinter ore is controlled to be <3.5 to obtain better sintering performance, and after balancing, when the proportion of vanadium titano-magnetite in the iron raw material for sinter production is 100%, the Ti02 content of sinter ore <3.5 can be met. At this time, the proportion of vanadium titano-magnetite in the blast furnace is 100%. The composition of sinter is shown in Table 13:

[0119] Table 13: Sinter composition table produced by vanadium titano-magnetite in Example 4

[0120] The composition of the generated blast furnace slag is shown in Table 14:

[0121] Table 14: Blast furnace slag composition table produced in Example 4

[0122] The actual results obtained by smelting according to the method of smelting high proportion of vanadium titano-magnetite in an oxygen blast furnace (including the heat schedule, charging method and tuyere gas injection parameters) of the present application are: the [V] content in the molten iron is 0.767%, the coke ratio is 260 kg / t, the coal ratio is 90 kg / t, and the distribution coefficient of vanadium element in molten iron and slag [V] / (V2O5) = 1.53 > 1.3. Compared with the traditional blast furnace, the fuel and power cost used in the smelting method of the present application is reduced by 53 yuan / ton of iron, and further, since the price of vanadium titano-magnetite is lower than that of ordinary iron ore, the ore matching cost of the present application is reduced by 310 yuan / ton, and CO2 emission is reduced by 35.2%.

[0123] Example 5: Top gas circulation example

[0124] The composition of the coke oven gas in the steel plant is shown in Table 15 below.

[0125] Table 15: Coke oven gas composition of Example 5

[0126] The composition of the reducing gas obtained after reforming the coke oven gas with steam in the heating furnace is shown in Table 16 below, the coke oven gas flow is 75 m 3 / t, and the steam flow is 15.9 m 3 / t.

[0127] Table 16: Reducing gas composition after reforming of coke oven gas in Example 5

[0128] According to the coke ratio 0.26 t / t, the coal ratio 0.07 t / t, and the tuyere oxygen blowing amount 191 Nm 3 / t, the composition of the bosh gas generated in the furnace is shown in Table 17 below, and the bosh gas amount is 1500 m 3 / t.

[0129] Table 17: Composition of Furnace Gas in Example 5

[0130] As the gas rises from the furnace belly, it undergoes a reduction reaction with iron oxides inside the furnace, producing metallic iron, H2O, and CO2. The composition of the top gas is shown in Table 18 below. The volume of top gas is 1500 m³. 3 / t.

[0131] Table 18: Composition of Top Gas in Example 5

[0132] The composition of the purified gas after removing CO2, H2O, and dust from the furnace top gas is shown in Table 19 below. The purified gas volume is 989 m³. 3 / t. It is evident that N2 is enriched in the purified coal gas. If a portion is not exported, N2 will further enrich and rise to over 25% in the next or multiple cycles of recycling. Therefore, a method is adopted to reduce the purified coal gas volume to 989m³. 3 55m in / t 3 / t of purified coal gas is delivered to other users, 934m 3 / t of purified coal gas is fed into the heating furnace for heating and then supplied to the blast furnace for recycling, but this 934m 3 The purified coal gas produced per ton cannot meet the blast furnace's blast energy requirements, so a portion of coke oven gas reforming is added. The purpose of supplementing with coke oven gas reforming is twofold: first, to increase blast energy and ensure hearth activity; and second, to dilute the N2 content of the gas inside the furnace.

[0133] Table 19: Composition of purified coal gas in Example 5

[0134] 934m 3 / t of purified coal gas enters the next round of recycling: In the coal gas heating furnace, purified coal gas with an N2 content of 21.09% is mixed with coke oven gas reforming gas with an N2 content of 4.7% to become high-temperature reducing gas and sent into the furnace. It is then mixed with CO produced by carbon combustion and reduction reaction in the furnace to become furnace gas with an N2 content of 13.91%. This cycle repeats, and the N2 content of the coal gas in the furnace remains stable at around 13.91%.

[0135] In summary, the smelting method of the present invention achieves blast furnace smelting with a vanadium-titanium iron ore ratio greater than 60%, a TiO2 mass fraction in blast furnace slag greater than 15% and less than 45%, and a CO2 emission reduction of more than 30%.

[0136] Although the specific embodiments of the present application are described in detail with reference to the accompanying drawings, it is not understood as a limitation to the scope of protection of the present patent. Various modifications and changes made by those skilled in the art which come within the scope of the claims described below are intended to fall within the scope of the present patent.

Claims

1. A method of oxygen blast smelting of high proportion vanadium titano-magnetite characterized in that, The method comprises the following steps: The blast furnace adopts pure oxygen injection, pure oxygen and hot coal gas are injected into the tuyere, iron materials and coke are added from the top of the blast furnace, the volume percentage of N2 in the top gas of the blast furnace is less than 25%, and the top gas of the blast furnace is recycled after removing CO2; The iron materials are pellet ores or the iron materials are pellet ores and at least one of the following materials: sintered ores and lump ores; The TiO2 content in the pellet ores is 3%-13%, the iron raw materials for producing the pellet ores are vanadium-titanium iron ores, and the mass percentage of the pellet ores in the iron materials of the blast furnace is greater than 30%; the mass fraction of TiO2 in the sintered ores is less than 5%; The mass fraction of TiO2 in the smelting generated blast furnace slag is greater than 15% and less than 45%, the blast furnace vanadium-titanium iron ore ratio is greater than 60%, and the blast furnace CO2 emission is reduced by 30%.

2. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by: The hot coal gas is the gas heated by a coal gas heating furnace, the gas sources of the coal gas heating furnace include coke oven gas, water vapor and purified coal gas, the flow of the coke oven gas sent into the coal gas heating furnace is 20 Nm 3 / t-200 Nm 3 / t, the ratio of the water vapor to the coke oven gas in terms of the amount of substance sent into the heating furnace is 0.10-0.30:

1.

3. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by: In the blast furnace smelting process, When the mass fraction of TiO2 in the blast furnace slag is greater than 15% and less than or equal to 18%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is greater than or equal to 0.4% and less than or equal to 0.8%; When the mass fraction of TiO2 in the blast furnace slag is greater than 18% and less than or equal to 20%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is greater than or equal to 0.3% and less than or equal to 0.7%; When the mass fraction of TiO2 in the blast furnace slag is greater than 20% and less than or equal to 25%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is greater than or equal to 0.10% and less than or equal to 0.6%; When the mass fraction of TiO2 in the blast furnace slag is greater than 25%, the sum of the mass fractions of [Si] and [Ti] in the molten iron is greater than or equal to 0.05% and less than or equal to 0.55%.

4. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by: The mass ratio of the iron materials to the coke in the blast furnace is 5.5-7.5:1, the mass ratio of the iron materials to the coal powder in the blast furnace is 15-40:1, the blast furnace fuel ratio in the blast furnace smelting process is less than 400 kg / t, and the coke ratio is less than 300 kg / t.

5. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by: The distribution coefficient of vanadium elements in the molten iron and the slag in the blast furnace smelting process is greater than 1.

1.

6. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by: The flow rate of the injected hot coal gas is 700 Nm 3 / t-1280 Nm 3 / t, the flow rate of the injected pure oxygen is 145 Nm 3 / t-245 Nm 3 / t.

7. A method of smelting high proportion vanadium titano-magnetite in an oxygen blast furnace as claimed in claim 1, characterized by, The charging method of the iron materials and the coke is as follows: at the blast furnace material surface height, a horizontal blast furnace section is taken, the section is equally divided into 11 equal-area annular rings, the rings are sequentially numbered from the inner ring to the outer ring, and the distribution system is as follows: 60%-80% of the coke is distributed in the 9th ring-11th ring and the 1st ring-5th ring, 20%-40% of the coke is distributed in the 6th ring-8th ring, 70%-90% of the iron materials are distributed in the 4th ring-10th ring, and 10%-30% of the iron materials are distributed in the 1st ring-3rd ring and the 11th ring.

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