Smelting method of high-vanadium molten iron

Abstract

The invention relates to the technical field of ironmaking, in particular to a smelting method of high-vanadium molten iron. The smelting method of the high-vanadium molten iron comprises the following steps that on the basis that a central coke adding and material distributing mode is adopted for blast furnace ironmaking, a viscosity reducer is added in the central area of a blast furnace, the material distributing system of the blast furnace is adjusted, and stable and smooth operation of blast furnace smelting of the high-vanadium molten iron is achieved; the viscosity reducer is prepared from SiC and Si3N4; the material distribution system of the blast furnace is adjusted by reducing the height of a material line and reducing the material distribution angle of an inner ring. The viscosity reducer is added in the central area of the blast furnace, so that the problem of hearth accumulation of the high-vanadium molten iron is effectively solved. Compared with a traditional smelting technology, on the basis that an existing blast furnace operation mode is not changed, the process steps are simplified, and the stability of the high-vanadium molten iron smelting furnace condition is improved.

Description

Technical Field

[0001] The invention relates to the technical field of iron making, in particular to a method for smelting high-vanadium molten iron. Background Art

[0002] High-vanadium hot metal mainly comes from the smelting process of vanadium-titanium magnetite. In recent years, with the extensive mining of vanadium-titanium magnetite in Panzhihua and other areas, the production of high-vanadium hot metal has become increasingly important in the metallurgical industry. Due to its high vanadium content, this molten iron exhibits the problem of excessive viscosity during the ironmaking process, especially in the blast furnace hearth area. The poor fluidity of the molten iron leads to serious accumulation, which in turn affects the stability of the furnace condition and the quality of the molten iron. In addition, the smelting of high-vanadium hot metal also faces other difficulties, such as harsh smelting conditions and difficult operation and control. These problems greatly limit the smelting efficiency and economic benefits of high-vanadium hot metal, and new methods are urgently needed to improve the fluidity of molten iron and improve production efficiency.

[0003] At present, there have been many studies and patents on the smelting technology of high-vanadium hot metal. Patent CN103966382B proposes a method for treating vanadium-containing hot metal and a method for smelting vanadium-titanium magnetite concentrate, with the focus on controlling the temperature of vanadium-containing hot metal to be higher than its theoretical liquidus temperature, and adding desiliconizing agent to the ladle in batches through bottom blowing operation, thereby extracting vanadium slag and hot metal. This technology mainly focuses on increasing the temperature of molten iron in order to improve the forward ability of subsequent processes. However, this method still has the problems of complex process and high energy consumption. In addition, patent CN103421923B proposes a method for smelting vanadium-containing hot metal, which uses vanadium-containing ore and carbonaceous reducing agent for direct reduction, and obtains vanadium-containing hot metal by further smelting. This patent takes into account the difference in characteristics between high-vanadium hot metal and ordinary hot metal, and improves the grade of extracted vanadium slag by optimizing the reduction process. However, this method still fails to fundamentally solve the furnace condition problem in the smelting of high-vanadium hot metal, especially in terms of furnace accumulation and excessive viscosity of molten iron. There are still great challenges. Summary of the invention

[0004] Based on the above content, the present invention provides a method for smelting high-vanadium molten iron to solve the problems of furnace accumulation and excessive viscosity of molten iron in the current smelting of high-vanadium molten iron.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for smelting high-vanadium molten iron, comprising the following steps:

[0007] On the basis of the central coke distribution mode in blast furnace ironmaking, viscosity reducer is added in the central area of ​​blast furnace, and the distribution system of blast furnace is adjusted to achieve stable and smooth smelting of high-vanadium hot metal in blast furnace;

[0008] The viscosity reducing agent includes SiC and Si3N4;

[0009] The adjustment of the charging system of the blast furnace includes lowering the charging line height and reducing the inner ring charging angle.

[0010] The second technical solution of the present invention is a method for reducing the viscosity during the smelting of high-vanadium molten iron, which adopts the above-mentioned smelting method of high-vanadium molten iron.

[0011] The present invention discloses the following technical effects:

[0012] The present invention effectively solves the problem of high-vanadium hot metal accumulation in the hearth by adding a viscosity reducer in the central area of ​​the blast furnace. Compared with the traditional smelting technology, the method of the present invention simplifies the process steps and improves the stability of the high-vanadium hot metal smelting furnace condition without changing the existing blast furnace operation mode.

[0013] The present invention is based on the central coke distribution mode in blast furnace ironmaking, combined with adding a certain amount of viscosity reducer in the central area of ​​the blast furnace, controlling its dosage and performance requirements, and reasonably adjusting the distribution system and coke quality indicators. By reasonably adding viscosity reducer in the blast furnace, the accumulation phenomenon in the hearth can be effectively reduced, and the smoothness of high-vanadium molten iron smelting can be maintained. The present invention has a simple process, controllable operation, significant production efficiency improvement, is suitable for large-scale industrial application, and has broad prospects. DETAILED DESCRIPTION

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0015] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0016] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0017] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0018] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0019] The "%" described in the present invention, unless otherwise specified, refers to mass percentage.

[0020] Although a number of technologies have been explored for the treatment of high-vanadium hot metal, most of these technologies focus on extracting vanadium slag or controlling smelting temperature, but are insufficient in reducing the viscosity of hot metal and improving the smoothness of furnace conditions. These technologies have not yet been able to effectively address the problem of hearth accumulation caused by excessively high hot metal viscosity in blast furnaces, making the smelting process of high-vanadium hot metal still face challenges in terms of stability and operational difficulty.

[0021] The present invention is based on the blast furnace center coke operation method, and a certain amount of highly reactive semi-coke is added to the coke arranged in the center area. From the perspective of reducing the CO2 and the blast furnace center coke to generate CO, a method for reducing the blast furnace coke ratio is proposed. The method has a simple production process, safe operation, and is easy to implement. At the same time, it reduces the amount of coke used, and has great significance for practical application.

[0022] The present invention provides a method for smelting high-vanadium molten iron, aiming to solve the problems of difficult furnace operation and serious accumulation in the furnace of high-vanadium molten iron in the prior art. The present invention is based on the central coke distribution mode, and achieves stable operation of the blast furnace by adding an appropriate amount of viscosity reducer to the central area of ​​the blast furnace, optimizing the distribution system and coke quality indicators. The viscosity reducer has special composition and performance requirements, and can effectively improve the fluidity and smoothness of the smelting process. The method of the present invention can significantly improve the smelting efficiency and furnace stability of high-vanadium molten iron, and has broad application prospects.

[0023] The first aspect of the present invention provides a method for smelting high-vanadium molten iron, comprising the following steps:

[0024] On the basis of the central coke distribution mode in blast furnace ironmaking, viscosity reducer is added in the central area of ​​blast furnace, and the distribution system of blast furnace is adjusted to achieve stable and smooth smelting of high-vanadium hot metal in blast furnace;

[0025] The viscosity reducing agent includes SiC and Si3N4;

[0026] The adjustment of the charging system of the blast furnace includes lowering the charging line height and reducing the inner ring charging angle.

[0027] In a preferred embodiment of the present invention, the amount of center coke added accounts for 22% to 28% of the mass of the total coke (excluding coke pieces).

[0028] In the present invention, the central coke amount is limited to the above parameter range for the following reasons: if the central coke amount is too high, coke will accumulate in the center, forming a ore-free space in a certain area. In this area, the gas flow is large, the gas utilization rate is significantly reduced, and the fuel consumption is high. If the central coke amount is too low, the blast furnace permeability will deteriorate, and the raw material requirements for vanadium-titanium magnetite smelting will become higher. Due to the regionality of steel enterprises and the economics of steel production, it is difficult to change their raw material requirements.

[0029] In a preferred embodiment of the present invention, the coke has a reactivity CRI of 18% to 26%, a CSR of 62% to 65%, and an average particle size of 51 mm to 53 mm.

[0030] In the present invention, the reason why coke is required to have low CRI (18% to 26%) and high CSR (62% to 65%) is as follows: because the low-temperature reduction pulverization rate and slag-iron ratio of vanadium-titanium sintered ore are much higher than those of ordinary ore blast furnace smelting, when CRI ≥ 26% and CRI < 62%, the smooth operation of the blast furnace cannot be guaranteed, and pipeline travel and suspended materials frequently occur, which seriously affects the air volume and output. Therefore, thermal reactivity is required to avoid the above phenomenon in coke.

[0031] In the present invention, the particle size of coke is limited to the above parameter range for the following reasons:

[0032] The particle size of coke is too small: Although the specific surface area is large, which is conducive to accelerating the carbon-oxygen reaction, for the smelting of vanadium-titanium ore, the too fast reaction rate may lead to local excessive reduction, producing substances such as TIC and TIN, affecting the recovery rate of vanadium.

[0033] The particle size of coke is too large: the reactivity is reduced and the full reduction of elements such as vanadium and titanium cannot be guaranteed.

[0034] In a preferred embodiment of the present invention, the viscosity reducer comprises SiC 75% to 95%, Si3N4 4% to 20%, and the remainder impurities, calculated by mass percentage. The sum of the mass percentages of SiC, Si3N4 and impurities is 100%.

[0035] Further preferably, the viscosity reducer used has a composition of 80%-85% SiC, 5%-8% Si3N4, and the remainder impurities in terms of mass percentage. The impurities may be one or more of CaO, MgO and Al2O3.

[0036] In the present invention, SiC and Si3N4 are both used to add Si to high-vanadium molten iron to reduce the viscosity of high-vanadium molten iron. When SiC and Si3N4 are added to the central area of ​​the blast furnace together with coke, they do not react with coke, thus avoiding affecting the quality of coke due to the addition of materials.

[0037] In a preferred embodiment of the present invention, the particle size of the viscosity reducer is 5 mm to 15 mm.

[0038] The reasons why the particle size of the viscosity reducer is limited to the above parameter range are as follows:

[0039] The particle size of the viscosity reducer is too large: when added to high-vanadium molten iron, the release of silicon will be too slow and the viscosity of the molten iron cannot be reduced in time. The regulation speed of the high-vanadium molten iron is slow, affecting the smelting efficiency.

[0040] The particle size of the viscosity reducer is too small: it will cause SiC to decompose quickly, silicon to be released too quickly, and it will not be able to fully react with the oxides in the high-vanadium molten iron, which will easily lead to uneven distribution of silicon in the molten iron and make it difficult to control the stability of the molten iron viscosity.

[0041] In a preferred embodiment of the present invention, the added amount of the viscosity reducer accounts for 0.4% to 1.1% of the mass of the high-vanadium molten iron.

[0042] The reasons why the amount of viscosity reducer added is limited to the above parameter range are as follows:

[0043] Too much viscosity reducer added: If too much viscosity reducer is added and the silicon content is too high, the silica in the molten iron will increase, and the reaction will generate a large amount of high-melting-point titanosilicate, thereby increasing the viscosity of the slag, which will worsen the fluidity of the molten iron and hinder the reduction of vanadium and iron.

[0044] Too little viscosity reducer added: Vanadium titanosite contains high levels of titanium and vanadium oxides, which melt at high temperatures to form molten iron with high viscosity. If too little viscosity reducer is added, the amount of silicon released is insufficient, and the viscosity of the molten iron of the vanadium titanosite cannot be effectively reduced, resulting in poor fluidity of the molten iron, which in turn affects the fluidity of the molten iron, resulting in inadequate reduction reaction, especially low reduction efficiency for vanadium and iron.

[0045] In a preferred embodiment of the present invention, when the viscosity reducer is loaded into a blast furnace, the viscosity reducer is first placed in a material tank so that the viscosity reducer preferentially falls into the central area of ​​the blast furnace.

[0046] In a preferred embodiment of the present invention, the adjustment of the charging system of the blast furnace includes: reducing the height of the charging line by 0.1-0.2 m and reducing the inner ring charging angle by 0.5°-1°.

[0047] In the present invention, if the material line is lowered too much, the material will be piled up more tightly, which will hinder the flow of gas in the furnace and reduce the permeability of the blast furnace. This will affect the distribution of coal gas in the furnace, resulting in a decrease in the efficiency of the reduction reaction. At the same time, the contact area between the coke and the gas in the furnace is reduced, and the heat conduction and reaction rate are reduced, resulting in uneven temperature distribution in the furnace, reduced thermal efficiency, and possibly unstable composition of high-vanadium molten iron.

[0048] If the inner ring material angle is too low, the viscosity reducer cannot be evenly added to the center.

[0049] In a preferred embodiment of the present invention, the vanadium content of the high-vanadium molten iron is 0.35wt% to 0.50wt%.

[0050] A second aspect of the present invention provides a method for reducing viscosity during the smelting of high-vanadium molten iron, using the above-mentioned smelting method of high-vanadium molten iron.

[0051] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0052] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] The blast furnace ironmaking in the embodiment of the present invention is adjusted on the basis of the conventional blast furnace ironmaking process, and the conventional blast furnace ironmaking process is carried out in the on-site blast furnace of Jiuquan Iron and Steel Enterprise; the high vanadium molten iron produced by the conventional blast furnace ironmaking process has a vanadium content of 0.37% and a viscosity of 4.51 mPa·s.

[0054] Example 1

[0055] A method for smelting high-vanadium molten iron comprises the following steps:

[0056] In the blast furnace ironmaking process, the central coke distribution mode is adopted, in which the central coke addition accounts for 24.55% of the total coke (excluding coke diced) mass. The CRI of the coke used is 20.36%, the CSR is 62.45%, and the average particle size is 51.98mm. To optimize the smelting process, a viscosity reducer is added to the central area of ​​the blast furnace (the viscosity reducer is added to the material tank at the same time as the coke, and the viscosity reducer is first laid in the material tank). Its main components include 81.22% SiC and 7.13% Si3N4. The particle size range of the viscosity reducer is 5mm to 13mm, and the amount added accounts for 0.83% of the mass of the high-vanadium molten iron. When the viscosity reducer is loaded into the blast furnace, the viscosity reducer is first laid in the material tank, and then the blast furnace distribution system is adjusted. The specific adjustments include: reducing the material line height by 0.13m and reducing the inner ring distribution angle by 0.5° to ensure that the viscosity reducer plays a full role in the central area. The vanadium content of the high-vanadium molten iron in this embodiment is 0.41%.

[0057] Through the above adjustment, the viscosity of high vanadium molten iron is 3.18mPa·s at 1450℃.

[0058] Example 2

[0059] A method for smelting high-vanadium molten iron comprises the following steps:

[0060] In the blast furnace ironmaking process, the central coke distribution mode is adopted, in which the central coke addition accounts for 26.20% of the total coke (excluding coke diced) mass. The CRI of the coke used is 22.56%, the CSR is 63.12%, and the average particle size is 51.88mm. To optimize the smelting process, a viscosity reducer is added to the central area of ​​the blast furnace (the viscosity reducer is added to the material tank at the same time as the coke, and the viscosity reducer is first laid in the material tank). Its main components include 84.51% SiC and 6.67% Si3N4. The particle size range of the viscosity reducer is 5mm to 11.5mm, and the amount added accounts for 1.02% of the mass of the high-vanadium molten iron. When the viscosity reducer is loaded into the blast furnace, the viscosity reducer is first laid in the material tank, and then the blast furnace distribution system is adjusted. The specific adjustments include: reducing the material line height by 0.16m and reducing the inner ring distribution angle by 0.8° to ensure that the viscosity reducer plays a full role in the central area. The vanadium content of the high-vanadium molten iron in this embodiment is 0.43%.

[0061] Through the above adjustment, the viscosity of high vanadium molten iron is 2.96mPa·s at 1450℃.

[0062] Example 3

[0063] A method for smelting high-vanadium molten iron comprises the following steps:

[0064] In the blast furnace ironmaking process, the central coke distribution mode is adopted, in which the central coke addition accounts for 25.14% of the total coke (excluding coke diced) mass. The CRI of the coke used is 23.16%, the CSR is 62.75%, and the average particle size is 51.44mm. To optimize the smelting process, a viscosity reducer is added to the central area of ​​the blast furnace (the viscosity reducer is added to the material tank at the same time as the coke, and the viscosity reducer is first laid in the material tank). Its main components include 84.24% SiC and 5.80% Si3N4. The particle size range of the viscosity reducer is 6.5mm to 15mm, and the amount added accounts for 0.65% of the mass of the high-vanadium molten iron. When the viscosity reducer is loaded into the blast furnace, the viscosity reducer is first laid in the material tank, and then the blast furnace distribution system is adjusted. The specific adjustments include: reducing the material line height by 0.11m and reducing the inner ring distribution angle by 0.5° to ensure that the viscosity reducer plays a full role in the central area. The vanadium content of the high-vanadium molten iron in this embodiment is 0.36%.

[0065] Through the above adjustment, the viscosity of high vanadium molten iron is 2.85mPa·s at 1450℃.

[0066] Comparative Example 1

[0067] The only difference from Example 2 is that the addition of the viscosity reducer is omitted, and the remaining steps and parameters are the same as those of Example 2.

[0068] At 1450°C, the viscosity of the high-vanadium molten iron prepared in this comparative example is 4.15 mPa·s.

[0069] Comparative Example 2

[0070] The only difference from Example 2 is that the main component of the viscosity reducer includes 91.18% SiC, the particle size range of the viscosity reducer is 5 mm to 11.5 mm (ie, Si3N4 is replaced by SiC), and the remaining steps and parameters are the same as those in Example 2.

[0071] At 1450°C, the viscosity of the high-vanadium molten iron prepared in this comparative example is 3.29 mPa·s.

[0072] Comparative Example 3

[0073] The only difference from Example 2 is that the step of adjusting the charging system of the blast furnace is omitted, and the remaining steps and parameters are the same as those of Example 2.

[0074] At 1450°C, the viscosity of the high-vanadium molten iron prepared in this comparative example is 3.43 mPa·s.

[0075] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for smelting high-vanadium molten iron, characterized in that: The following steps are involved: On the basis of the central coke distribution mode in blast furnace ironmaking, viscosity reducer is added in the central area of ​​blast furnace, and the distribution system of blast furnace is adjusted to achieve stable and smooth smelting of high-vanadium hot metal in blast furnace; The viscosity reducing agent includes SiC and Si3N4; The adjustment of the charging system of the blast furnace includes lowering the charging line height and reducing the inner ring charging angle.

2. The smelting method of high vanadium hot metal according to claim 1, characterized in that: The amount of center coke added accounts for 22% to 28% of the total coke (excluding coke cubes) mass.

3. The smelting method of high vanadium hot metal according to claim 2, characterized in that: The reactivity CRI of the coke is 18% to 26%, the CSR is 62% to 65%, and the average particle size is 51 mm to 53 mm.

4. The smelting method of high vanadium hot metal according to claim 1, characterized in that: Calculated by mass percentage, the viscosity reducer includes 75% to 95% SiC, 44% to 20% Si3N, and the remainder impurities.

5. The smelting method of high vanadium hot metal according to claim 1, characterized in that: The particle size of the viscosity reducer is 5 mm to 15 mm.

6. The smelting method of high vanadium hot metal according to claim 1, characterized in that: The added amount of the viscosity reducer accounts for 0.4% to 1.1% of the mass of the high-vanadium molten iron.

7. The smelting method of high vanadium hot metal according to claim 1, characterized in that: When the viscosity reducer is loaded into the blast furnace, the viscosity reducer is first placed in the material tank so that the viscosity reducer falls into the central area of ​​the blast furnace first.

8. The smelting method of high vanadium hot metal according to claim 1, characterized in that: The adjustment of the charging system of the blast furnace includes: lowering the charging line height by 0.1-0.2 m and lowering the inner ring charging angle by 0.5°-1°.

9. The smelting method of high vanadium hot metal according to claim 1, characterized in that: The vanadium content in the high-vanadium iron water is 0.35wt% to 0.50wt%.

10. A method for reducing the viscosity of high-vanadium hot metal during smelting, characterized in that: A smelting method for high-vanadium molten iron according to any one of claims 1 to 9.