Method for reducing alkalinity of high-titanium slag in blast furnace smelting of schreyerite

Abstract

The invention relates to the technical field of blast furnace ironmaking, and discloses a method for reducing alkalinity of high-titanium slag in blast furnace smelting of schreyerite, which comprises the following steps: (1) adjusting a furnace charge structure: controlling the mass ratio of sintered ore to vanadium-titanium pellets to be (9-11): (9-10), and controlling the raw ore proportion to be 2-6wt%; (2) the furnace condition and the furnace temperature are stabilized, the air quantity fluctuation is controlled within 100 m < 3 >, and the oxygen quantity fluctuation is controlled within 1000 m < 3 >; and (3) the temperature of the blast furnace molten iron is controlled to be 1430-1470 DEG C. By reducing the alkalinity of the slag, the normal emission of the slag iron is not influenced, and the effect of reducing the fuel consumption of each ton of iron is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace ironmaking, and in particular to a method for reducing the basicity of high-titanium slag by smelting vanadium-titanium ore in a blast furnace. Background Art

[0002] Vanadium-titanium magnetite is a symbiotic composite ore with multiple valuable elements such as iron, vanadium, and titanium. It is also an important vanadium and titanium resource. Vanadium-titanium magnetite is highly concentrated in Panxi region of my country, but the sulfur load of vanadium-titanium ore resources in this region is generally high, and the sulfur load level of blast furnace is about 5-6.0kg / TFe. In order to ensure the desulfurization capacity of slag and the qualified rate of molten iron (sulfur content), the basicity of blast furnace slag (slag binary basicity = CaO mass percentage in slag / SiO in slag) was calculated in the early stage. 2 The mass percentage of slag is generally controlled at a high level of 1.18-1.23 times, and its slag iron discharge is good, and the molten iron desulfurization and slag fluidity meet the production needs. However, in order to achieve a slag binary basicity of 1.18-1.23, a large amount of limestone flux needs to be added to dilute the sintered ore grade, and the cost of molten iron metal materials will increase. It has been calculated that a slag basicity of 1.20 requires an increase in metal material cost of 15-20 yuan / ton of iron relative to a slag basicity of 1.10 under the same ore blending conditions; and if the slag binary basicity is simply reduced, the desulfurization capacity of the blast furnace slag will drop significantly. In order to maintain the desulfurization capacity of the molten iron, the furnace temperature level will inevitably be greatly increased, resulting in high blast furnace smelting fuel consumption indicators and increased coke ratio, which is unfavorable to the company's operating costs.

[0003] In addition, during the smelting process of high-titanium vanadium-titanium ore, the high-melting-point minerals generated in the slag phase increase the melting temperature of the slag, increase the slag viscosity, make it difficult to separate the slag from the iron, and easily produce foamy slag, which restricts the production of blast furnaces. 2 The grade entering the furnace is nearly 5.0% lower than that of ordinary ore smelting, and the slag ratio is high. The larger the slag volume, the higher the iron loss, which is not conducive to the company's energy conservation and consumption reduction. Summary of the invention

[0004] In view of the above shortcomings, the present invention aims to provide a method for reducing the basicity of high-titanium slag in blast furnace smelting vanadium-titanium ore, which can reduce the fuel consumption per ton of iron without affecting the normal discharge of slag by reducing the basicity of slag.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions.

[0006] A method for reducing the basicity of high-titanium slag by smelting vanadium-titanium ore in a blast furnace comprises the following steps:

[0007] (1) Adjusting the charge structure: controlling the mass ratio of sintered ore to vanadium-titanium pellets to (9-11):(9-10), and controlling the raw ore ratio to 2-6wt%;

[0008] (2) Stabilize furnace conditions and temperature, and control air volume fluctuation within 100m 3 The oxygen fluctuation is controlled within 1000m 3 within;

[0009] (3) The temperature of molten iron in blast furnace is controlled at 1430~1470℃.

[0010] Furthermore, the binary basicity of the slag is 1.05-1.15.

[0011] Furthermore, in the furnace charge structure, the flux for slag making is selected from limestone powder and quicklime.

[0012] Furthermore, the mixture of the sintered ore includes 25-45wt% of vanadium-titanium concentrate powder.

[0013] More preferably, the mixture of the sintered ore includes 30wt% of vanadium-titanium concentrate powder.

[0014] Furthermore, the coal ratio of the blast furnace is controlled at 155-180kg / ton iron.

[0015] Furthermore, the fuel ratio of the blast furnace is controlled at 530-560 kg / ton iron.

[0016] The physical properties of the slag change during the smelting of vanadium-titanium ore. As the proportion of vanadium-titanium ore increases, the apparent viscosity changes from small to large, and the slag becomes thicker, which is an important reason affecting blast furnace smelting. Controlling the fluidity of slag iron and adjusting and optimizing the chemical composition, organizational structure and content of related phases in the slag are conducive to improving the smelting conditions of vanadium-titanium ore. 2 The different contents are mainly achieved by adjusting the slag basicity to improve the slag fluidity, and increasing the MgO content accordingly to improve the slag desulfurization capacity and alkali removal capacity. In other words, while reducing the binary basicity of the slag, the MgO content in the slag is appropriately increased in order to obtain a higher ternary basicity.

[0017] The present invention increases the content of MgO and MnO in the slag by adjusting the charge structure, that is, increasing the proportion of pelletized ore; by stabilizing the furnace condition and temperature, the blast furnace operation adjustment is operated in a small range (the air volume fluctuation is controlled within 100m 3 The oxygen fluctuation is controlled within 1000m 3 In daily operation, the physical heat is controlled within the range of 1430℃-1470℃. Under this temperature, the overall viscosity of the high titanium slag system is low and the fluidity is good. In the process of reducing the slag basicity, it can better meet the production needs; thus achieving the effect of controlling the slag basicity within the range of 1.05-1.15.

[0018] By reducing the slag basicity, the following technical effects can be achieved:

[0019] (1) Suppressing the content of TiO in slag 2 ) Over-reduction: After the slag basicity is reduced, the charge needs to be adjusted to ensure the fluidity of the slag. By increasing the proportion of pellets and reducing the amount of flux added, the MnO content in the slag can be increased. The MnO in the slag composition has a great influence on (TiO 2 ) has an inhibitory effect on over-reduction. At the same time, the presence of (MnO) in the slag weakens the reduction of (TiO2) by C to a certain extent.

[0020] (2) Improve the fluidity of slag: When the basicity of high-titanium slag is 0.8, the corresponding crystallization temperature of perovskite is 1320℃. When the basicity changes to 1.3, its crystallization temperature increases to 1452.3℃. At the same time, in the process of increasing the basicity from 0.8 to 1.3, the crystallization temperature of titanium spinel also increases from 1277.8℃ to 1396.8℃. The increase in the crystallization temperature of perovskite and titanium spinel is manifested in the increase of slag viscosity in the macroscopic properties of slag. Therefore, the temperature of high-titanium slag is in a relatively low range, and its viscosity increases with the increase of basicity. Considering that in order to ensure that the precipitated mineral phase in high-titanium slag is relatively concentrated and the viscosity is appropriate, TiO 2 The mass fraction is 23%, and the binary basicity of high titanium slag should be controlled to be 1.05-1.15. In addition, due to the guarantee of ternary basicity of slag, the MgO content in slag can reduce slag viscosity and improve slag fluidity, which is conducive to various reactions between slag and iron.

[0021] (3) Improve the desulfurization capacity of slag: Ion migration process is carried out at the interface between liquid slag and iron. Neutral atomic sulfur in molten iron absorbs electrons in slag and turns into sulfur anions S at the interface between slag and iron. 2- Enter the slag, and the oxygen negative ions O in the slag 2- At the interface, it loses electrons and becomes a neutral atom, enters the molten iron, and combines with C in the molten iron to form CO, which is discharged from the molten iron. Due to the presence of other elements such as Si and Mn in the molten iron, these elements also interact with S in the molten iron, accelerating the desulfurization reaction in the form of coupled reactions. Due to the reduction in slag viscosity, the flowability of the slag-iron mixture in the furnace is improved, and the kinetic conditions of slag desulfurization are improved, thereby accelerating desulfurization. The equilibrium distribution coefficient of sulfur between slag and iron increases with the increase of slag flowability. Analysis shows that: first, with the decrease of slag binary basicity, the equilibrium distribution coefficient of sulfur between slag and iron gradually increases due to the improvement of kinetic conditions LS. Second, because it improves the fluidity of the slag, it improves the kinetic conditions of desulfurization, further exerting the desulfurization capacity of high titanium, which is not high originally, thereby achieving the purpose of improving the fluidity of the slag and the desulfurization effect. From the basic principle of blast furnace smelting kinetics, the disadvantage of increasing the coke ratio caused by deliberately increasing the furnace temperature to obtain better desulfurization capacity during blast furnace high vanadium-titanium ratio smelting is avoided. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The technical solution of the present invention is to increase the content of MgO and MnO in the slag by adjusting the charge structure, that is, increasing the proportion of pellets and reducing the amount of flux added; by stabilizing the furnace condition and temperature, the blast furnace operation adjustment is operated in a small range (the air volume fluctuation is controlled within 100m 3 The oxygen fluctuation is controlled within 1000m 3 In daily operation, the physical heat is controlled within the range of 1430℃-1470℃. Under this temperature, the overall viscosity of the high titanium slag system is low and the fluidity is good. In the process of reducing the slag basicity, it can better meet the production needs; thus achieving the effect of controlling the slag basicity within the range of 1.05-1.15.

[0024] The operating method embodiments of the present invention are as follows:

[0025] During blast furnace production, iron-containing raw materials, coke fuel, and slag-making flux are loaded from the top of the furnace, and preheated air and pulverized coal fuel are blown in from the tuyere located at the bottom of the furnace along the furnace periphery. At high temperatures, the carbon in the fuel burns with the oxygen in the blown air to produce carbon monoxide and hydrogen. The oxygen in the iron-containing raw materials is removed during the rising process in the furnace, thereby reducing iron. The molten iron is discharged from the iron mouth, and the impurities in the iron-containing raw materials that are not reduced combine with the slag-making flux to produce slag, which is discharged from the slag mouth.

[0026] The iron-containing raw materials include sintered ore and vanadium-titanium pellets, the mass ratio of the sintered ore to the vanadium-titanium pellets is (9-11):(9-10), and the raw ore ratio is controlled to be 2-6wt%. Furthermore, the sintered ore mixture includes 25-45wt% of vanadium-titanium concentrate powder, and more preferably, the sintered ore mixture includes 30wt% of vanadium-titanium concentrate powder.

[0027] The fuel includes coke and pulverized coal. The blast furnace fuel ratio is controlled at 530-560kg / ton iron, and the coal ratio is controlled at 155-180kg / ton iron, which is economical and reasonable and ensures smooth furnace operation.

[0028] The slag-making flux includes limestone powder and quicklime, and the grade of sintered ore is improved by adjusting the charge structure, reducing the flux amount, and reducing the iron-to-slag ratio.

[0029] To stabilize the furnace condition and temperature, the blast furnace operation and adjustment are all carried out within a small range (the air volume fluctuation is controlled within 100m3 The oxygen fluctuation is controlled within 1000m 3 within).

[0030] In daily operation, physical heat is controlled within the range of 1430℃-1470℃. At this temperature, the overall viscosity of the high-titanium slag system is low and the fluidity is good, which can better meet production needs in the process of reducing the basicity of the slag.

[0031] Expected benefits: According to the empirical formula for ironmaking, if the slag basicity decreases by 0.1, the fuel consumption will decrease by 0.2%, that is, if the slag basicity is reduced from 1.18 to 1.13, the fuel consumption can be reduced by 570×(1.18-1.13)×0.2=5.7kg / ton iron in theory, saving 2.286 yuan / ton of cost. kg燃料 ×5.7kg / ton iron=13.03 yuan / ton iron.

[0032] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for reducing the basicity of high-titanium slag in smelting vanadium-titanium ore in a blast furnace, characterized in that: The following steps are involved: (1) Adjusting the charge structure: controlling the mass ratio of sintered ore to vanadium-titanium pellets to (9-11):(9-10), and controlling the raw ore ratio to 2-6wt%; (2) Stabilize furnace conditions and temperature, and control air volume fluctuation within 100m 3 The oxygen fluctuation is controlled within 1000m 3 within; (3) The temperature of molten iron in blast furnace is controlled at 1430~1470℃.

2. The method for reducing the basicity of high-titanium slag in blast furnace smelting of vanadium-titanium ore according to claim 1, characterized in that: The binary basicity of the high titanium slag is 1.05-1.

15.

3. The method for reducing the basicity of high-titanium slag in blast furnace smelting of vanadium-titanium ore according to claim 1, characterized in that: The slag-making flux in the furnace charge structure includes limestone powder and quicklime.

4. The method for reducing the basicity of high-titanium slag in blast furnace smelting of vanadium-titanium ore according to claim 1, characterized in that: The mixed material of the sintered ore includes 25-45wt% of vanadium-titanium concentrate powder.

5. The method for reducing the basicity of high-titanium slag in smelting vanadium-titanium ore in a blast furnace according to claim 4, characterized in that: The mixed material of the sintered ore includes 30wt% of vanadium-titanium concentrate powder.

6. The method for reducing the basicity of high-titanium slag in blast furnace smelting of vanadium-titanium ore according to claim 1, characterized in that: Control the coal ratio of the blast furnace at 155-180kg / ton iron.

7. The method for reducing the basicity of high-titanium slag in blast furnace smelting of vanadium-titanium ore according to claim 1, characterized in that: Control the fuel ratio of the blast furnace at 530-560kg / ton iron.