Method for improving fluidity of high titanium slag in blast furnace smelting of vanadium titano-magnetite

Abstract

The invention relates to the technical field of blast furnace smelting, and discloses a method for improving the flowability of high titanium slag in blast furnace smelting of vanadium titano-magnetite, and the method comprises the following steps: stabilizing a furnace charge structure of 48wt% of vanadium-titanium sintered ore, 48wt% of vanadium-titanium pellet ore and 4wt% of vanadium-titanium magnetite raw ore, smelting in the furnace, and adding 2-5wt% of dolomite and a proper amount of manganese powder into the vanadium-titanium sintered ore to improve the flowability of the slag. More preferably, the flowability of the high titanium slag is further improved by combining optimization of operation parameters such as large air volume, high air temperature, high oxygen enrichment rate and high top pressure of the blast furnace. According to the method for improving the flowability of the high-titanium slag, on the premise that the charging proportion of schreyerite is not reduced, generation of a high-melting-point phase in the slag can be effectively controlled, the viscosity of the slag is reduced, the flowability of the slag is improved, the smelting efficiency of a blast furnace is improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnace smelting, in particular to a method for improving the fluidity of high-titanium slag in blast furnace smelting of vanadium-titanium magnetite. BACKGROUND

[0002] Vanadium-titanium magnetite is a kind of complex ore with iron, vanadium and titanium as main components. China is one of the countries with the richest vanadium-titanium magnetite resources, mainly concentrated in the Panxi region of Sichuan and also distributed in Chengde, Hebei.

[0003] The main method for blast furnace smelting of vanadium-titanium magnetite is to produce sintered ore by sintering vanadium-titanium iron concentrate and ordinary fine ore, and to produce oxidized pellet by pelletizing vanadium-titanium iron concentrate and ordinary iron concentrate. Then, the sintered ore, pellet and a small amount of lump ore are added into the blast furnace together with coke in a certain proportion, the coke is combusted by blast at the lower part to produce reducing gas, the reducing gas rises and falls with the descending of the ore to reduce the ore, and then the smelting process is completed by melting and dropping into the hearth to realize the separation of slag and iron.

[0004] Compared with smelting ordinary iron ore, the core difficulty of blast furnace smelting of vanadium-titanium magnetite lies in that, under the strong reducing atmosphere and high temperature smelting conditions of the blast furnace, the titanium (Ti) reduced in the blast furnace combines with carbon and nitrogen in the blast furnace to form high-melting-point compounds titanium carbide (TiC) and titanium nitride (TiN) into high-titanium slag, which makes the slag and iron viscous, and the slag and iron cannot be separated, the fluidity is poor, the slag and iron are difficult to discharge, and the blast furnace hearth is seriously blocked.

[0005] At present, the blast furnace smelting of vanadium-titanium magnetite mainly improves the fluidity of the slag by reducing the proportion of vanadium-titanium entering the furnace and strictly controlling the content of titanium dioxide in the slag ≤22.5% during the batching process. However, for steel enterprises in the Panxi region, vanadium-titanium magnetite is the most cost-effective ore, and reducing the proportion of vanadium-titanium entering the furnace will inevitably increase the proportion of imported ore and increase the cost of ironmaking. Therefore, under the premise of maintaining the existing proportion of vanadium-titanium ore, how to improve the fluidity of the slag is a problem to be solved. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a method for improving the fluidity of high-titanium slag in blast furnace smelting of vanadium-titanium magnetite, which improves the viscosity and fluidity of high-titanium slag under the premise of maintaining a high proportion of vanadium-titanium magnetite, and ensures the smooth operation of the blast furnace and the improvement of smelting efficiency.

[0007] In order to achieve the above technical effects, the present application provides the following technical solutions.

[0008] The application discloses a method for improving the fluidity of high-titanium slag in blast furnace smelting of vanadium-titanium magnetite, which comprises the following steps: mixing vanadium-titanium magnetite, fuel, flux and returned ore according to a proportion to prepare vanadium-titanium sinter, mixing fine powder of vanadium-titanium magnetite and a binder according to a proportion to prepare vanadium-titanium pellet, and taking a composition structure of "48wt% vanadium-titanium sinter+48wt% vanadium-titanium pellet+4wt% vanadium-titanium magnetite" as the iron-containing raw material for smelting. The fuel is a mixture of coke powder and manganese powder, the mass ratio of the coke powder to the manganese powder in the mixture is (2-4):1, and the adding amount of the fuel is 5-6wt%. The flux comprises limestone and dolomite, the adding amount of the limestone is used to control the CaO / SiO2 ratio of the vanadium-titanium sinter to be 1.8-2.2, and the adding amount of the dolomite is 2-5wt%.

[0009] The application ensures the relative stability of the burden composition in the blast furnace smelting process by taking the stable burden structure "48wt% vanadium-titanium sinter+48wt% vanadium-titanium pellet+4wt% vanadium-titanium magnetite" for smelting, and reduces the influence of the burden composition fluctuation on the slag; the dolomite provides MgO, and the application controls the MgO content in the slag in the range of 8.0-9.5% and the magnesium-aluminum ratio in the range of 0.60-0.65 by adding 2-5wt% of the dolomite in the vanadium-titanium sinter, thereby improving the desulfurization capacity of the slag and providing O 2- The long chain structure formed by Al2O3 or SiO2 is broken, and the slag viscosity is reduced; the application can make the manganese content in the slag be 0.8-1.5% by adding manganese powder in the sinter fuel, and the reduction damage and inhibition of TiO2 are realized by using the MnO in the high-temperature direct reduction strong endothermic region of the blast furnace, so that the high-melting-point phases TiC, TiN and TiCN are inhibited from reacting, thereby reducing the slag viscosity and improving the slag fluidity.

[0010] Further, in some embodiments of the application, the blast furnace smelting air volume is controlled to be 3250-3350 m 3 / min.

[0011] Further, in some embodiments of the application, the blast furnace smelting air temperature is controlled to be greater than or equal to 1200℃ Further, in some embodiments of the application, the blast furnace smelting oxygen enrichment rate is controlled to be greater than or equal to 4.5%.

[0012] Further, in some embodiments of the application, the blast furnace smelting pressure is controlled to be greater than or equal to 180Kpa.

[0013] The application optimizes the blast furnace operation parameters, uses large air volume (3250-3350 m 3The high-titanium slag has high TiO2 content, high TiO content, high [Ti] content, high TiC content, high TiN content and high TiCN content, and has high viscosity and poor fluidity. The present application is characterized in that the high-titanium slag is prepared by using a high-titanium vanadium ore, a high proportion of vanadium-titanium ore, a high proportion of return fines, a high proportion of flux, a high proportion of coke, a high proportion of limestone, a high proportion of binder, a high proportion of fluxing agent, a high proportion of fuel, a high proportion of oxygen, a high proportion of wind temperature, a high proportion of oxygen enrichment and a high proportion of top pressure operation, so that the reduction process of TiO2→TiO→[Ti]→TiC, TiN and TiCN is not fully reacted, and the generation of TiC, TiN and TiCN is greatly reduced, so that the fluidity of the high-titanium slag is improved.

[0014] Further, the binder is added in an amount of 1-1.5wt% in the vanadium-titanium pellet.

[0015] Further, the binder is selected from bentonite.

[0016] Bentonite is an organic binder commonly used in pellet, which mainly functions to improve the balling rate and green ball strength (falling strength and compressive strength) of the green ball, but bentonite is an acidic gangue, which can introduce SiO2 and Al2O3, thus increasing the slag amount, so the addition amount thereof needs to be controlled to 1-1.5wt%.

[0017] Further, the return fines are added in an amount of 30-35wt% in the vanadium-titanium sinter. In the vanadium-titanium sinter, the return fines are the nucleation core, and the addition amount of 30-35wt% of the return fines can ensure the formation of sufficient ball cores.

[0018] Compared with the prior art, the present application has the following beneficial effects: The method for improving the fluidity of high-titanium slag provided by the present application can effectively control the generation of high-melting-point phases in the slag, reduce the viscosity of the slag, improve the fluidity of the slag, and thus improve the smelting efficiency of the blast furnace and reduce the production cost, without reducing the proportion of vanadium-titanium ore entering the furnace. DETAILED DESCRIPTION

[0019] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to specific embodiments.

[0020] Embodiment 1 Embodiment 1 of the present application was carried out on the applicant's 1# sintering trolley, 1# chain grate, 2# rotary kiln and 3# blast furnace.

[0021] 1. Preparation of vanadium-titanium sinter: 5wt% coke powder, an appropriate amount of limestone (to control the basicity (CaO / SiO2 ratio) of the sinter to 1.8-2.2), 35wt% return fines and the rest vanadium-titanium magnetite powder were mixed and granulated to obtain a mixture, and the mixture was uniformly laid on the 1# sintering trolley through a distributor and sintered, and then cooled, crushed and sieved to obtain vanadium-titanium sinter (particle size 10-50mm) for entering the blast furnace.

[0022] 2. Preparation of vanadium-titanium pellet: 1.2 wt% bentonite and the balance of vanadium-titanium magnetite concentrate powder are mixed uniformly, and then the qualified green balls are uniformly laid on the grate bed of the 1# chain grate machine through the distributor after preheating, and then enter the 2# rotary kiln for roasting and solidification to obtain vanadium-titanium pellet for blast furnace.

[0023] 3. The composition structure of "48 wt% vanadium-titanium sinter + 48 wt% vanadium-titanium pellet + 4 wt% vanadium-titanium magnetite green ore" is used as the iron-containing raw material for smelting, and the fuel (coke) and flux (limestone, dolomite, etc.) are adjusted in real time according to the furnace condition. In the smelting process of the blast furnace, the viscosity of the slag is analyzed by sampling. According to the analysis results, the viscosity of the slag is 0.264 Pa·S at a working temperature of 1460℃.

[0024] Example 2: Example 2 of the present application is carried out on the applicant's 1# sintering trolley, 1# chain grate machine, 2# rotary kiln and 3# blast furnace. Example 2 is an improvement on Example 1, aiming to improve the slag fluidity.

[0025] 1. Preparation of vanadium-titanium sinter: 4 wt% coke powder, 1 wt% manganese powder, appropriate amount of limestone (to control the sinter basicity (CaO / SiO2 ratio) at 1.8-2.2), 2 wt% dolomite, 35 wt% return fines and the balance of vanadium-titanium magnetite powder are mixed to obtain a mixture, and the mixture is uniformly laid on the 1# sintering trolley through the distributor after sintering, and then cooled, crushed and screened to obtain vanadium-titanium sinter (particle size 10-50mm) for blast furnace.

[0026] 2. Preparation of vanadium-titanium pellet: 1.2 wt% bentonite and the balance of vanadium-titanium magnetite concentrate powder are mixed uniformly, and then the qualified green balls are uniformly laid on the grate bed of the 1# chain grate machine through the distributor after preheating, and then enter the 2# rotary kiln for roasting and solidification to obtain vanadium-titanium pellet for blast furnace.

[0027] 3. The composition structure of "48 wt% vanadium-titanium sinter + 48 wt% vanadium-titanium pellet + 4 wt% vanadium-titanium magnetite green ore" is used as the iron-containing raw material for smelting, and the fuel (coke) and flux (limestone, dolomite, etc.) are adjusted in real time according to the furnace condition. At the same time, the blast furnace smelting operation parameters are optimized, and the blast furnace smelting operation parameters of large air volume (3250-3350 m3 / min), high air temperature (≥1200℃), high oxygen enrichment rate (≥4.5%) and high top pressure (≥180kpa) are adopted. In the smelting process of the blast furnace, the viscosity of the slag is analyzed by sampling. According to the analysis results, the viscosity of the slag is 0.124 Pa·S at a working temperature of 1460℃.

[0028] Compared with Example 1, the slag viscosity is reduced by 0.14 Pa·S, the reduction rate is 53%, the slag fluidity is obviously improved, the stability of the furnace condition is promoted, at the same time, the reduction of the slag viscosity promotes the substantial reduction of the iron content in the slag, the iron loss of the blast furnace is reduced from 2.5% to 1.6%, the reduction rate is 0.9%, and the cost reduction per ton of iron is 25 yuan / ton of iron.

[0029] Example 3 Example 1 of the application is carried out on the applicant's 1# sintering trolley, 1# chain grate machine, 2# rotary kiln and 4# blast furnace.

[0030] 1. Preparation of vanadium-titanium sinter: take 6wt% coke powder, appropriate amount of limestone (control sinter basicity (CaO / SiO2 ratio) at 1.8-2.2), 30wt% return fines and the rest of vanadium-titanium magnetite powder to mix and granulate to obtain the mixture, uniformly spread the mixture on the 1# sintering trolley through the distributor, and after sintering, cooling, crushing and screening, vanadium-titanium sinter for blast furnace (particle size 10-50mm) is obtained.

[0031] 2. Preparation of vanadium-titanium pellet: take 1.2wt% bentonite and the rest of vanadium-titanium magnetite concentrate powder to mix and ball, and the qualified green balls are uniformly spread on the grate bed of the 1# chain grate machine through the distributor, preheated and then enter the 2# rotary kiln for roasting and solidification to obtain vanadium-titanium pellet for blast furnace.

[0032] 3. Take "48wt% vanadium-titanium sinter + 48wt% vanadium-titanium pellet + 4wt% vanadium-titanium magnetite ore" as the iron-containing raw material for smelting, and adjust the fuel (coke) and flux (limestone, dolomite, etc.) according to the furnace condition. In the smelting process of the blast furnace, the slag viscosity is analyzed by sampling. According to the analysis result, at the working temperature of 1460℃, the slag viscosity is 0.274Pa·S.

[0033] Example 4 Example 1 of the application is carried out on the applicant's 1# sintering trolley, 1# chain grate machine, 2# rotary kiln and 4# blast furnace. Example 4 is an improvement of Example 3, aiming to improve the slag fluidity.

[0034] 1. Preparation of vanadium-titanium sinter: take 4wt% coke powder, 2wt% manganese powder, appropriate amount of limestone (control sinter basicity (CaO / SiO2 ratio) at 1.8-2.2), 5wt% dolomite, 30wt% return fines and the rest of vanadium-titanium magnetite powder to mix and granulate to obtain the mixture, uniformly spread the mixture on the 1# sintering trolley through the distributor, and after sintering, cooling, crushing and screening, vanadium-titanium sinter for blast furnace (particle size 10-50mm) is obtained.

[0035] 2. Preparation of vanadium-titanium pellet: 1.2wt% bentonite and the rest of vanadium-titanium magnetite concentrate powder are mixed uniformly and then balling, qualified green balls are evenly laid on the grate bed of 1# chain grate through the distributor, preheated and then enter 2# rotary kiln for roasting and solidification to obtain vanadium-titanium pellet for blast furnace.

[0036] 3. The composition structure of "48wt% vanadium-titanium sinter + 48wt% vanadium-titanium pellet + 4wt% vanadium-titanium magnetite green ore" is used as the iron-containing raw material for smelting, the fuel (coke) and flux (limestone, dolomite, etc.) are adjusted in real time according to the furnace condition. At the same time, the blast furnace smelting operation parameters are optimized, and the blast furnace smelting operation parameters of large air volume (3250-3350 m3 / min), high air temperature (≥1200℃), high oxygen enrichment rate (≥4.5%) and high top pressure (≥180kpa) are adopted. In the smelting process of the blast furnace, the viscosity of the slag is analyzed by sampling. According to the analysis results, at the working temperature of 1460℃, the viscosity of the slag is 0.136Pa·S.

[0037] Compared with example 1, the slag viscosity is reduced by 0.138 Pa·S, and the decline rate is 50%.

[0038] The above is only the preferred embodiment of the present application, it should be pointed out that the above preferred embodiment should not be regarded as limiting the present application, the protection scope of the present application should be limited by the scope defined by the claims. For ordinary skilled in the art, without departing from the spirit and scope of the present application, a number of improvements and refinements can also be regarded as the protection scope of the present application.

Claims

1. A method for improving the fluidity of high-titanium slag in blast furnace smelting of vanadium-titanium magnetite, characterized in that: Vanadium-titanium magnetite, fuel, flux and returned ore are mixed in proportion to prepare vanadium-titanium sinter, and vanadium-titanium magnetite fine powder and binder are mixed in proportion to prepare vanadium-titanium pellet, and a composition of "48wt% vanadium-titanium sinter + 48wt% vanadium-titanium pellet + 4wt% vanadium-titanium raw ore" is used as the iron-containing raw material for smelting in a blast furnace; The fuel is a mixture of coke powder and manganese powder, the mass ratio of coke powder to manganese powder in the mixture is (2-4) : 1, and the addition amount of the fuel is 5-6wt%. The flux includes limestone and dolomite, the addition amount of the limestone is to control the CaO / SiO2 ratio of the vanadium-titanium sinter to be 1.8-2.2, and the addition amount of the dolomite is 2-5wt%.

2. The method of claim 1, wherein: The blast volume for controlling the blast furnace smelting is 3250-3350 m 3 / min.

3. The method of claim 1, wherein: The blast furnace smelting is controlled to have a wind temperature of ≥1200℃.

4. The method of claim 1, wherein: The blast furnace smelting is controlled to have an oxygen enrichment rate of ≥4.5%.

5. The method of claim 1, wherein: The blast furnace smelting is controlled to have a pressure of ≥180Kpa.

6. The method of claim 1, wherein: The addition amount of the binder in the vanadium-titanium pellet is 1-1.5wt%.

7. The method of claim 6, wherein: The binder is selected from bentonite.

8. The method of claim 1, wherein: The addition amount of the returned ore in the vanadium-titanium sinter is 30-35wt%.