Titanium-containing blast furnace slag smelting method

Abstract

The invention discloses a titanium-containing blast furnace slag smelting method which is characterized in that a hollow graphite electrode is adopted as a conductive material, a high-temperature-resistant ceramic tube is arranged in the hollow graphite electrode, CH4 gas is introduced from the top of the graphite electrode to the bottom of the graphite electrode through the ceramic tube in the smelting process, the CH4 gas is heated and decomposed into C and H2, and the C generated through decomposition has extremely high activity. According to the smelting method, under the condition that the temperature of the slag at the initial stage of smelting is low, compared with traditional coke powder serving as a reducing agent, the slag can rapidly react with the titanium-containing blast furnace slag to generate CO gas, the generated CO stirs the melt in the rising and escaping process from the bottom of a molten pool, hot slag at the pole center circle position of an electric furnace floats upwards and flows to the periphery, and therefore the smelting efficiency is improved. Cold slag outside a pole center circle sinks and flows to the center, is heated and then floats upwards to promote dynamic circulation of the slag, so that the reaction kinetics of the titanium-containing blast furnace slag is improved, and the reaction efficiency of the titanium-containing blast furnace slag is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rare metal refining, and in particular to a method for smelting titanium-containing blast furnace slag. Background Art

[0002] my country's Panxi region is rich in vanadium-titanium magnetite resources. The proven reserves of vanadium-titanium magnetite account for more than 95% of the country's total reserves, and the titanium resources are 870 million tons, accounting for 90.54% and 35.17% of my country's and the world's titanium resources respectively. After the "blast furnace ironmaking" process, about 50% of the titanium in Panxi vanadium-titanium magnetite enters the blast furnace slag and becomes titanium-containing blast furnace slag, with a TiO2 content of 20-25%. In order to comprehensively recycle the titanium resources in the titanium-containing blast furnace slag and turn the titanium-containing blast furnace slag into treasure, Pansteel independently developed the "high-temperature carbonization-low-temperature chlorination" titanium extraction process route of titanium-containing blast furnace slag.

[0003] Among them, the main principle of preparing carbide slag by high-temperature carbonization of titanium-containing blast furnace slag is: using titanium-containing blast furnace slag as raw material and conventional metallurgical coke as reducing agent, smelting is carried out in an AC furnace at a high temperature of 1300~1600℃ to obtain molten carbide slag, and the slag removal process adopts a water quenching process to obtain water-quenched slag, and the water-quenched slag is then dehydrated and ground to obtain finished carbide slag of suitable particle size. The main smelting reactions are: TiO2+2C = TiC +2CO2TiO2+C = Ti2O3+CO FeO+C=Fe+CO At present, the reducing agent used in the process of producing carburized slag by high-temperature carbonization of titanium-containing blast furnace slag is mainly conventional metallurgical coke. Conventional metallurgical coke has the characteristics of high mechanical strength, high strength after reaction, and low reactivity, while the coke used for high-temperature carbonization of titanium-containing blast furnace slag requires high reactivity, but does not require high coke strength. Therefore, the use of conventional metallurgical coke to smelt titanium-containing blast furnace slag has the disadvantages of poor reaction kinetics in the early stage of smelting and low reaction efficiency.

[0004] Therefore, it is of great significance to develop a reducing agent that can replace metallurgical coke and make it more suitable for the high reactivity of coke for high-temperature carbonization of titanium-containing blast furnace slag, thereby improving the reaction kinetics of titanium-containing blast furnace slag and improving the reaction efficiency of titanium-containing blast furnace slag. Summary of the invention

[0005] The object of the present invention is to provide a method for smelting titanium-containing blast furnace slag. In the method, CH4 is introduced through a graphite electrode and electrolytically decomposed into C with higher activity. Compared with the traditional coke powder as a reducing agent, the method can quickly react with the titanium-containing blast furnace slag to generate CO gas. The generated CO rises from the bottom of the molten pool and stirs the melt during its escape, so that the hotter slag at the polar center circle of the electric furnace floats to the periphery, and the colder slag outside the polar center circle sinks to the center, and then floats after being heated, thereby promoting the dynamic circulation of the slag, thereby improving the reaction kinetics of the titanium-containing blast furnace slag, improving the reaction efficiency of the titanium-containing blast furnace slag, and solving the problems of poor reaction kinetics and low reaction efficiency in the early stage of smelting titanium-containing blast furnace slag when conventional metallurgical coke is used to smelt titanium-containing blast furnace slag.

[0006] Furthermore, the H2 generated by decomposition becomes a part of the recovered flue gas through flue gas recovery, thereby increasing the calorific value of the recovered flue gas.

[0007] In order to achieve the above object, the present invention provides a method for smelting titanium-containing blast furnace slag, comprising the following steps: Step (1): when adding the titanium-containing blast furnace slag into the carbonization furnace through the slag turning pot, adding the pre-mixed coke powder into the carbonization electric furnace; the mass of the pre-mixed coke powder is 4%-7% of the mass of the titanium-containing blast furnace slag; Step (2): inserting a graphite electrode into a first position in the titanium-containing blast furnace slag in the carbonization furnace, wherein the graphite electrode is a hollow conductive material with a built-in ceramic tube, and CH4 gas is continuously introduced from the top to the bottom of the graphite electrode through the ceramic tube to supply electricity for smelting; Step (3): during the smelting process, the CO gas concentration is monitored, and when the CO gas concentration reaches 40%, the remaining coke powder is added, and the graphite electrode is raised to the second position to recover the flue gas; the mass of the remaining coke powder is 4%-5% of the mass of the titanium-containing blast furnace slag; Step (4): During the addition of the remaining coke powder, the power supply for smelting and the introduction of CH4 gas are continued; after the remaining coke powder is completely added, the graphite electrode is inserted down to the first position of step (2), and the introduction of CH4 gas is stopped, and the power supply for smelting is continued; Step (5): monitor the CO gas concentration, and start slag tapping when the CO gas concentration drops to 30%. The slag tapping process uses high-pressure water to directly impact the molten slag to obtain water-quenched slag. After the water-quenched slag is left to cool, it is dried and crushed using a crushing process to obtain finished carbonized slag.

[0008] The titanium-containing blast furnace slag smelting method of the present invention adopts a hollow graphite electrode as a conductive material, and a high-temperature resistant ceramic tube is built in. During the smelting process, a ceramic tube is used to pass CH4 gas from the top to the bottom of the graphite electrode. The CH4 gas is decomposed into C and H2 by heat. The decomposed C has extremely high activity. When the slag temperature is low in the initial stage of smelting, compared with the traditional use of coke powder as a reducing agent, it can quickly react with the titanium-containing blast furnace slag and generate CO gas. The generated CO stirs the melt during the process of rising and escaping from the bottom of the molten pool, so that the hotter slag at the pole center circle of the electric furnace floats to the periphery, and the colder slag outside the pole center circle sinks to the center, and then floats after being heated, promoting the dynamic circulation of the slag, thereby improving the reaction kinetics of the titanium-containing blast furnace slag and improving the reaction efficiency of the titanium-containing blast furnace slag. At the same time, the H2 generated by decomposition becomes a part of the recovered flue gas through flue gas recovery, thereby improving the calorific value of the recovered flue gas. Therefore, the smelting kinetic conditions of the titanium-containing blast furnace slag, the reaction efficiency of the titanium-containing blast furnace slag, and the calorific value of the recovered flue gas can be improved.

[0009] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in the step (1), the mass of the titanium-containing blast furnace slag added to the carbonization furnace is 55t-70t, and the number of tank turnovers is 3-6.

[0010] According to the method for smelting titanium-containing blast furnace slag described in the present invention, preferably, in the step (1), the titanium-containing blast furnace slag and the pre-mixed coke powder are premixed in the following manner: for the first two slag turning pots, the titanium-containing blast furnace slag in each slag turning pot is poured into a carbonizing electric furnace for slag turning, and then 1 t of the pre-mixed coke powder is added; the titanium-containing blast furnace slag in the third slag turning pot is poured into a carbonizing electric furnace for slag turning, and then the remaining pre-mixed coke powder is added.

[0011] The premixing method of the present invention is advantageous for fully mixing the premixed coke powder with the titanium-containing blast furnace slag, and is advantageous for the carbonization reaction of the titanium-containing blast furnace slag.

[0012] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in the step (2), the first position is the position where the bottom of the graphite electrode is flush with the lower edge of the slag outlet.

[0013] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in the step (2), the first position is 10 cm away from the refractory bricks at the bottom of the furnace.

[0014] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in step (2), the flow rate of CH4 gas introduced is 500-800m 3 / h.

[0015] According to the method for smelting titanium-containing blast furnace slag described in the present invention, preferably, in the step (3), the second position is where the bottom of the graphite electrode is flush with the upper edge of the slag outlet. At this time, lifting the graphite electrode by 20 cm can reduce the temperature of the refractory material at the bottom of the furnace, which is beneficial to reducing the erosion of the refractory material at the bottom of the furnace.

[0016] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in the step (3), the rate of adding the remaining coke powder is 80 kg / min.

[0017] According to the method for smelting titanium-containing blast furnace slag described in the present invention, preferably, in the step (4), the graphite electrode is inserted down to the first position of step (2). At this time, a large amount of TiC is generated in the slag. TiC is a solid particle with a density greater than that of liquid slag, and will gradually sink to the bottom of the slag, causing the viscosity of the slag at the bottom of the furnace to be high. The insertion of the graphite electrode is conducive to increasing the temperature of the slag at the bottom of the furnace, reducing the viscosity of the slag at the bottom of the furnace, facilitating the slag discharge at the bottom of the furnace, and avoiding the phenomenon of slag accumulation at the bottom of the furnace due to the low temperature and high viscosity of the slag at the bottom of the furnace.

[0018] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, in the step (5), the crushing process dries the water-quenched slag and crushes it to 100 mesh-400 mesh.

[0019] According to the method for smelting titanium-containing blast furnace slag of the present invention, preferably, the carbonization furnace is a three-phase AC electric furnace with a rated power of 25 MVA.

[0020] The beneficial effects of the present invention are: The method for smelting titanium-containing blast furnace slag of the present invention adopts a hollow graphite electrode as a conductive material, and is internally provided with a high-temperature resistant ceramic tube. During the smelting process, CH4 gas is introduced from the top to the bottom of the graphite electrode through the ceramic tube. The CH4 gas is decomposed into C and H2 by heat. The decomposed C has extremely high activity. When the slag temperature is relatively low at the initial stage of smelting, it can react quickly with the titanium-containing blast furnace slag to generate CO gas compared with traditional coke powder. The generated CO rises from the bottom of the molten pool and stirs the melt during the process of escaping, so that the hotter slag at the pole center circle of the electric furnace floats to the periphery, and the colder slag outside the pole center circle sinks to the center, and then floats after being heated, thereby promoting the dynamic circulation of the slag, thereby improving the reaction kinetics of the titanium-containing blast furnace slag and improving the reaction efficiency of the titanium-containing blast furnace slag.

[0021] At the same time, the H2 generated by decomposition becomes part of the recovered flue gas through flue gas recovery, thereby increasing the calorific value of the recovered flue gas. Compared with the existing technology, it can improve the smelting kinetic conditions of titanium-containing blast furnace slag, increase the reaction efficiency of titanium-containing blast furnace slag, and increase the calorific value of recovered flue gas, and can be further extended to other slag smelting industries. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments.

[0023] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0024] The main components of the titanium-containing blast furnace slag and the industrial analysis components of the coke powder used in the examples and comparative examples of the present invention are shown in Table 1 and Table 2, respectively.

[0025] Table 1 Main component indexes of titanium-containing blast furnace slag / %

[0026] Table 2 Industrial analysis composition of coke powder / % reducing agent <![CDATA[Volatile matter d > <![CDATA[Fixed carbon d > <![CDATA[Ash d > Coke powder 2.31 84.60 13.09 Example 1 The carbonization furnace used in this embodiment is a three-phase AC electric furnace with a rated power of 25MVA; the particle size of the coke powder is 200 mesh-1mm.

[0027] The titanium-containing blast furnace slag used is molten titanium-containing blast furnace slag which is transported by rail to the slag turning point of the carbonization electric furnace through a slag tank car, and then is broken by a heavy hammer and added to the carbonization electric furnace through a chute. The main components of the titanium-containing blast furnace slag are shown in Table 1.

[0028] The smelting method of titanium-containing blast furnace slag of Example 1 comprises the following steps: Step (1): adding 60 tons of titanium-containing blast furnace slag into the carbonization furnace through a slag turning pot in four batches; when turning the first two pots, the titanium-containing blast furnace slag in each slag pot is poured into the carbonization electric furnace for slag turning, and then 1 tons of pre-mixed coke powder is added; the titanium-containing blast furnace slag in the third slag pot is poured into the carbonization electric furnace for slag turning, and then 2 tons of pre-mixed coke powder is added; Step (2): After the titanium-containing blast furnace slag is added, the bottom of the graphite electrode is inserted down to the same level as the bottom edge of the slag outlet, 10 cm away from the refractory bricks at the bottom of the furnace, and power is supplied for smelting. The transformer gear of the carbonization furnace is controlled at gear 5, and a ceramic tube is set in the middle of the graphite electrode to continuously introduce CH4 gas from the top to the bottom of the graphite electrode, with a flow rate of 600m 3 / h.

[0029] Step (3): After smelting for 26 minutes, the flue gas detection system detected that the CO gas concentration reached 40%, the average current fluctuation value was 2550A, and the average flue gas flow rate was 7190m 3 / h, CO generation is 1198.3m 3, start adding 3t of remaining coke powder at a rate of 80kg / min. When starting to add the remaining coke powder, lift the bottom of the graphite electrode by 20cm to the same level as the upper edge of the slag outlet, continue to introduce CH4 gas, and start to recover the flue gas.

[0030] Step (4): After the coke powder is completely added, the bottom of the graphite electrode is inserted down to the same level as the lower edge of the slag outlet, 10 cm away from the refractory bricks at the bottom of the furnace, and the CH4 gas is stopped, and the power supply for smelting is continued.

[0031] Step (5): After smelting for 17 minutes, the CO gas concentration is monitored by the flue gas detection system to drop to 30%, and slag discharge is started and flue gas recovery is stopped. The recovered flue gas composition is shown in Table 3; the slag discharge process uses high-pressure water to directly impact the molten slag to obtain water-quenched slag; after the water-quenched slag is stored in the slag yard for 2-3 days, the water-quenched slag is dried and crushed to 100 mesh-400 mesh by a crushing process to obtain a finished carbonized slag as shown in Table 4, which is used for the low-temperature chloride titanium dioxide process.

[0032] Comparative Example 1 The existing smelting process used in Comparative Example 1, in which the carbonization furnace, titanium-containing blast furnace slag and coke powder used are the same as those in Example 1, comprises the following steps: Step (1): adding 60 tons of titanium-containing blast furnace slag into the carbonization furnace through the slag turning pot in four times; when turning the first two pots, the titanium-containing blast furnace slag in each slag pot is poured into the carbonization electric furnace for slag turning, and then 1 tons of pre-mixed coke powder is added; the titanium-containing blast furnace slag in the third slag pot is poured into the carbonization electric furnace for slag turning, and then 2.2 tons of pre-mixed coke powder is added; Step (2): After the titanium-containing blast furnace slag is added, the bottom of the graphite electrode is inserted down to the same level as the lower edge of the slag outlet, 10 cm away from the refractory bricks at the bottom of the furnace, and power is supplied for smelting. The transformer gear of the carbonization furnace is controlled at gear 5.

[0033] Step (3): After 26 minutes of smelting, the flue gas detection system detected that the CO gas concentration reached 26%, the average current fluctuation value was 1750A, and the average flue gas flow rate was 7140m 3 / h, CO generation is 773.5m 3 After smelting for 42 minutes, the flue gas detection system detected that the CO gas concentration reached 40%, and 3 tons of residual coke powder was added at a rate of 80 kg / min. When the residual coke powder was added, the bottom of the graphite electrode was lifted 20 cm to the same level as the upper edge of the slag outlet, and the flue gas was recovered. The flue gas composition is shown in Table 3.

[0034] Step (4): After the coke powder is completely added, insert the bottom of the graphite electrode to the same level as the lower edge of the slag outlet, 10 cm away from the refractory bricks at the bottom of the furnace, and continue to supply electricity for smelting.

[0035] Step (5): After smelting for 20 minutes, the CO gas concentration is monitored by the flue gas detection system and drops to 30%, then slag discharge is started and flue gas recovery is stopped. The recovered flue gas composition is shown in Table 3. The slag discharge process uses high-pressure water to directly impact the molten slag to obtain water-quenched slag. After the water-quenched slag is stored in the slag yard for 2-3 days, the water-quenched slag is dried and crushed to 100 mesh-400 mesh by a crushing process to obtain a finished carbonized slag as shown in Table 4, which is used for the low-temperature chloride titanium dioxide process.

[0036] Table 3 Main components and calorific value of recovered flue gas

[0037] Table 4 Main components of carbonized slag / %

[0038] The patented method is used for smelting. When the smelting time is 26 minutes, the CH4 inlet flow rate is 600m 3 / h, the CH4 input mass is about 260kg for 26min, assuming that it is completely decomposed into C and H2, the mass of C generated by decomposition is 195kg, and the pre-provisioned coke powder is 4t, then the mass of carbon that can participate in the reaction in the carbonization furnace molten pool is 4.195t, which is basically the same as the 4.2t coke powder pre-provisioned by the traditional smelting method in Comparative Example 1. When the smelting method of this patent is used, when smelting for 26min, under the condition of consistent transformer gear position (consistent power supply voltage), the average current fluctuation value of the smelting method of this patent is larger, indicating that the reaction in the electric furnace in the early stage of smelting of the smelting method of this patent is more active, and when the mass of C that can participate in the reaction in the carbonization furnace molten pool is basically the same, the higher CO gas concentration and larger generation amount indicate that the carbonization reaction efficiency is faster. This shows that through the patented smelting method, when the molten pool temperature is low in the initial smelting stage, compared with the traditional smelting method, the C generated by the thermal decomposition of CH4 gas quickly reacts with the titanium-containing blast furnace slag to generate CO gas, and the generated CO rises from the bottom of the molten pool and stirs the melt during the process of escaping, so that the hotter slag at the center of the electric furnace floats to the periphery, and the colder slag outside the center sinks to the center, and then floats after being heated, promoting the dynamic circulation of the slag, thereby improving the reaction kinetics of the titanium-containing blast furnace slag and improving the reaction efficiency of the titanium-containing blast furnace slag.

[0039] It should be particularly pointed out that the various components or steps in the above-mentioned embodiments can be cross-linked, replaced, added, or deleted with each other. Therefore, the combinations formed by these reasonable arrangements and combinations should also fall within the scope of protection of the present invention, and the scope of protection of the present invention should not be limited to the embodiments.

[0040] The above are exemplary embodiments disclosed in the present invention. The order disclosed in the above embodiments of the present invention is for description only and does not represent the advantages and disadvantages of the embodiments. However, it should be noted that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope disclosed in the embodiments of the present invention (including the claims) is limited to these examples. Various changes and modifications may be made without departing from the scope defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0041] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for smelting titanium-containing blast furnace slag, characterized in that: The steps include: Step (1): when adding the titanium-containing blast furnace slag into the carbonization furnace through the slag turning pot, adding the pre-mixed coke powder into the carbonization electric furnace; the mass of the pre-mixed coke powder is 4%-7% of the mass of the titanium-containing blast furnace slag; Step (2): inserting a graphite electrode into a first position in the titanium-containing blast furnace slag in the carbonization furnace, wherein the graphite electrode is a hollow conductive material with a built-in ceramic tube, and CH4 gas is continuously introduced from the top to the bottom of the graphite electrode through the ceramic tube to supply electricity for smelting; Step (3): during the smelting process, the CO gas concentration is monitored, and when the CO gas concentration reaches 40%, the remaining coke powder is added, and the graphite electrode is raised to the second position to recover the flue gas; the mass of the remaining coke powder is 4%-5% of the mass of the titanium-containing blast furnace slag; Step (4): During the addition of the remaining coke powder, the power supply for smelting and the introduction of CH4 gas are continued; after the remaining coke powder is completely added, the graphite electrode is inserted down to the first position of step (2), and the introduction of CH4 gas is stopped, and the power supply for smelting is continued; Step (5): monitor the CO gas concentration, and start slag tapping when the CO gas concentration drops to 30%. The slag tapping process uses high-pressure water to directly impact the molten slag to obtain water-quenched slag. After the water-quenched slag is left to cool, it is dried and crushed using a crushing process to obtain finished carbonized slag.

2. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (1), the mass of titanium-containing blast furnace slag added to the carbonization furnace is 55t-70t, and the number of tank turnovers is 3-6.

3. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (1), the titanium-containing blast furnace slag and the pre-mixed coke powder are premixed in the following manner: for the first two slag turning pots, the titanium-containing blast furnace slag in each slag turning pot is poured into the carbonization electric furnace for slag turning, and then 1 t of the pre-mixed coke powder is added; the titanium-containing blast furnace slag in the third slag turning pot is poured into the carbonization electric furnace for slag turning, and then the remaining pre-mixed coke powder is added.

4. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (2), the first position is where the bottom of the graphite electrode is flush with the lower edge of the slag outlet.

5. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (2), the first position is 10 cm away from the refractory bricks at the bottom of the furnace.

6. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In step (2), the flow rate of CH4 gas is 500-800m 3 / h.

7. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (3), the second position is where the bottom of the graphite electrode is flush with the upper edge of the slag outlet.

8. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (3), the remaining coke powder is added at a rate of 80 kg / min.

9. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: In the step (5), the crushing process dries the water-quenched slag and crushes it to 100-400 meshes.

10. The method for smelting titanium-containing blast furnace slag according to claim 1, characterized in that: The carbonization furnace is a three-phase AC electric furnace with a rated power of 25MVA.

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