Method for smelting ferrovanadium from high alkali metal vanadium oxide

Abstract

The invention relates to the technical field of vanadium smelting, and discloses a method for smelting ferrovanadium from a high alkali metal vanadium oxide, which comprises the following steps: mixing conventional vanadium pentoxide, an aluminum product and lime in proportion to form a first prefabricated material, mixing the high alkali metal vanadium oxide, the conventional vanadium pentoxide, the aluminum product and the lime in proportion to form a second prefabricated material, adding the first prefabricated material to the bottom of a smelting furnace, adding the second prefabricated material to the upper part of the smelting furnace, and igniting at the upper part for self-propagating smelting; after smelting is finished, the molten slag is subjected to supplementary heating; after supplementary heating, a reducing agent is injected into the molten slag for alkali removal, and corundum slag is obtained. By optimizing the raw material ratio and improving the smelting process, high-alkali-metal vanadium oxide is efficiently utilized, meanwhile, corrosion of alkali metal oxide to a furnace lining is reduced, smelting safety and stability are guaranteed, meanwhile, the quality of ferrovanadium and corundum slag products is improved, and the requirement of the industry for improving the smelting technology of the high-alkali-metal vanadium oxide is met.

Description

Technical Field

[0001] This invention relates to the field of vanadium metallurgy, and more particularly to a method for smelting ferrovanadium from high-alkali metal vanadium oxides. Background Technology

[0002] Ferrovanadium alloys are currently the most widely used vanadium microalloying master alloys. Vanadium can combine with carbon and nitrogen in steel to form fine and dispersed carbonitrides, which play a role in grain refinement and precipitation strengthening, thereby improving the comprehensive mechanical properties of steel. At present, ferrovanadium alloys are mainly prepared by electroaluminothermic reduction or electrosiliconothermic reduction processes. The electroaluminothermic reduction method has become the mainstream ferrovanadium alloy preparation process due to its advantages such as high heat release per unit area, good product quality, and environmental friendliness.

[0003] The smelting of ferrovanadium requires the use of magnesia-based refractory materials, primarily magnesia sand, which has poor resistance to the corrosion of low-melting-point alkali metal oxides in the slag. Currently, the aluminothermic process for ferrovanadium smelting in China mainly uses vanadium pentoxide, aluminum products, lime, and iron filings as raw materials. More than 90% of the vanadium pentoxide produced domestically is produced using the sodium-based process. Based on the V₂O₅-Na₂O and V₂O-K₂O phase diagrams, it can be seen that some vanadium pentoxide contains extremely high levels of alkali metal oxides, resulting in a low liquid phase formation temperature, which is beneficial for improving the fluidity of liquid vanadium pentoxide. However, in the traditional electrothermal process, when using vanadium flakes with high alkali metal oxide content to smelt high-vanadium ferrovanadium, the corrosion of the furnace lining by these oxides is extremely severe, even posing a risk of furnace leakage.

[0004] Therefore, there is a need to improve the existing methods for smelting ferrovanadium from high-alkali metal vanadium oxides. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for smelting ferrovanadium from high-alkali metal vanadium oxides. By optimizing the raw material ratio and improving the smelting process, this method can achieve efficient utilization of high-alkali metal vanadium oxides while reducing the erosion of the furnace lining by alkali metal oxides, ensuring safe and stable smelting, and improving the quality of ferrovanadium and corundum slag products, thus meeting the industry's demand for improved smelting technology of high-alkali metal vanadium oxides.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for smelting ferrovanadium from high-alkali vanadium oxide, comprising: S1 mixes conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form the first pre-material. It also mixes high-alkali metal vanadium oxide, conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form the second pre-material. The first pre-material is added to the bottom of the smelting furnace, and the second pre-material is added to the top of the smelting furnace. The furnace is then ignited at the top for self-propagating smelting. After the S2 smelting is completed, the molten slag is reheated. After S3 is heated, a reducing agent is injected into the molten slag to remove alkali, resulting in corundum slag.

[0007] In some embodiments, in S1, the raw material ratio of the first preform is conventional vanadium pentoxide: aluminum product: lime at a ratio of 2:(0.98-1):(0.9-0.1) by mass. The raw material ratio of the second precast material by mass is (0.5-1.5): (1.5-0.5): (0.95-1): (1.2-1.5).

[0008] In some embodiments, in S1, the total content of Na2O and K2O in the high alkali metal vanadium oxide is ≤8% by mass percentage, the content of V2O5 is ≥90%, and the particle size of the high alkali metal vanadium oxide is less than 20 mm.

[0009] In some implementations, in S2, a graphite electrode is used for supplementary heating, and the supplementary heating time is 3-6 minutes.

[0010] In some embodiments, in S3, the reducing agent is aluminum powder, and the aluminum powder contains ≥98% Al by mass percentage.

[0011] In some embodiments, in S3, the power source for the injection is high-pressure nitrogen, and the O content in the high-pressure nitrogen is ≤0.5% by volume percentage.

[0012] In some implementations, the smelting furnace is a cylindrical furnace.

[0013] In some embodiments, in S1, the aluminum product is aluminum granules or aluminum shavings, wherein the particle size of the aluminum granules is 3-8 mm, the length of the aluminum shavings is no more than 10 mm, and the mass percentage content of Al in the aluminum product is ≥97%.

[0014] In some implementations, during S1, the maximum temperature inside the smelting furnace is controlled at 2000-2400°C, and the smelting reaction lasts for 15-25 minutes.

[0015] In some embodiments, the total content of Na2O and K2O in the corundum slag is ≤0.1%.

[0016] The present invention has at least the following beneficial technical effects: This invention achieves efficient smelting of ferrovanadium from high-alkali metal oxides by placing vanadium oxides at the top and using a self-propagating reaction while simultaneously increasing the lime ratio to ensure a more complete aluminothermic reaction. Under high-temperature conditions, some alkali metal oxides are reduced by aluminum and discharged with the reaction fumes. After the reaction is complete, heat is replenished by electric heating, and low-melting-point alkali metals are used for further focusing. Then, aluminum powder is injected to reduce the alkali metal oxides again. The alkali metals produced by reduction are vaporized in the molten high temperature and discharged with the nitrogen flow. This achieves efficient smelting of ferrovanadium from high-alkali metal oxides. Ultimately, the alkali metal oxide content in corundum slag is no higher than 0.03%, the vanadium recovery rate reaches over 98.1%, the ferrovanadium product quality meets the requirements of GB / T 4139-2012, the MgO content in the slag is reduced to below 10%, and the slag-to-iron ratio is reduced by more than 10%. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of an embodiment of a method for smelting ferrovanadium from high-alkali metal vanadium oxides provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0020] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0021] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] like Figure 1The present invention illustrates a method for smelting ferrovanadium from high-alkali metal vanadium oxides, comprising: S1 mixes conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form the first pre-material. It also mixes high-alkali metal vanadium oxide, conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form the second pre-material. The first pre-material is added to the bottom of the smelting furnace, and the second pre-material is added to the top of the smelting furnace. The furnace is then ignited at the top for self-propagating smelting. After the S2 smelting is completed, the molten slag is reheated. After S3 is heated, a reducing agent is injected into the molten slag to remove alkali, resulting in corundum slag.

[0023] Furthermore, in S1, the first preform is composed of conventional vanadium pentoxide, aluminum products, and lime in a mass ratio of 2:(0.98-1):(0.9-0.1). Conventional vanadium pentoxide serves as the basic vanadium source, the aluminum products can be aluminum granules or aluminum shavings (aluminum granules with a particle size of 3-8 mm, aluminum shavings with a length ≤10 mm, and an Al content ≥97%) as the reducing agent, and lime (CaO) plays a role in adjusting the basicity of the slag.

[0024] The second pre-formulated material is a mixture of high-alkali vanadium oxide, conventional vanadium pentoxide, aluminum products, and lime in a mass ratio of (0.5-1.5):(1.5-0.5):(0.95-1):(1.2-1.5). The high-alkali vanadium oxide must meet the following requirements: total Na₂O and K₂O content ≤8%, V₂O₅ content ≥90%, and particle size <20mm. Its combination with conventional vanadium pentoxide can balance the vanadium content and alkali metal concentration in the raw materials.

[0025] Specifically, the first pre-formed material is added to the bottom of the cylindrical furnace as a bottom reaction bed, which reduces direct contact between the high-alkali metal raw material and the furnace lining. The second pre-formed material is laid on top, forming a layered structure. Ignition in the upper part initiates a self-propagating reaction, with the maximum temperature controlled at 2000-2400℃ for 15-25 minutes. The self-propagating reaction is sustained by the exothermic reaction of the raw material itself, reducing external energy consumption. Simultaneously, the layered structure slows the diffusion of alkali metal oxides into the furnace lining, allowing them to be discharged with the flue gas. In this invention, high-alkali metal vanadium oxides are placed in the upper layer, and the self-propagating reaction begins from the top. The high temperature promotes the preferential discharge of alkali metal oxides with the flue gas. The bottom first pre-formed material acts as a "buffer layer," reducing direct contact between the high-alkali metal raw material and the furnace lining, thus delaying erosion.

[0026] In S2, after the smelting reaction is complete, the molten slag may partially solidify due to a drop in temperature. Graphite electrodes are used to supplement this solidification for 3-6 minutes. The purpose of this supplementary heating is to maintain the fluidity of the slag, creating a uniform reaction environment for the subsequent alkali removal process, and to prevent premature solidification of the slag, which would make the alkali metal coating difficult to remove.

[0027] In step S3, aluminum powder is used as a reducing agent, with an Al content ≥98%. The strong reducing properties of aluminum are utilized to reduce residual alkali metal oxides in the molten slag to elemental alkali metals. High-pressure nitrogen is used as the injection power source. The amount of aluminum powder injected is determined based on the molten slag mass. The aluminum powder is uniformly injected into the molten slag using high-pressure nitrogen, promoting a complete reduction reaction and achieving the purpose of removing alkali metals. In some embodiments, the injection time is ≥100s, and the nitrogen content in the high-pressure nitrogen is ≤0.5%.

[0028] After the reaction is completed, corundum slag is obtained, in which the total content of Na2O and K2O is ≤0.1% and the vanadium recovery rate is ≥98.1%. It can be recycled as a raw material for refractory materials to achieve resource recycling.

[0029] This invention uses high-alkali metal vanadium oxide as one of the main raw materials. By placing the high-alkali metal vanadium oxide in the upper part, a self-propagating reaction is carried out. At the same time, the proportion of lime is increased to make the aluminothermic reaction more complete. Under high temperature conditions, some alkali metal oxides are reduced by aluminum and discharged with the reaction fumes. After the reaction is completed, heat is supplemented by electric heating, and low-melting-point alkali metals are used for further focusing. Then, aluminum powder is sprayed to reduce the alkali metal oxides again. The alkali metals produced by reduction are vaporized in the molten high temperature and discharged with the nitrogen flow. This realizes the efficient smelting of ferrovanadium from high-alkali metal oxides.

[0030] This invention is applicable to self-propagating ferrovanadium smelting. By placing high-alkali metal vanadium oxide in the upper layer, it facilitates the removal of alkali metal oxides. These oxides are then removed through secondary deep reduction using injected aluminum powder. This ensures the smooth progress of the reactions Na₂O + Al = Al₂O₃ + Na(g) and K₂O + Al = Al₂O₃ + K(g), preventing alkali metal oxides from remaining in the slag for extended periods, which could damage the mineral lattice of magnesia refractories and compromise refractory quality. Rapid removal of alkali metals helps improve vanadium recovery, ultimately enabling the smelting of ferrovanadium using high-alkali metal oxides. This achieves an alkali metal oxide content in corundum slag not exceeding 0.03%, a vanadium recovery rate of over 98.1%, and ferrovanadium product quality meeting the requirements of GB / T 4139-2012. The MgO content in the slag is reduced to below 10%, and the slag-to-iron ratio is reduced by more than 10%.

[0031] The present invention will be further explained and described below with reference to specific embodiments.

[0032] Example 1 The first ratio of mixed precast material was selected using a conventional vanadium pentoxide:aluminum products:lime mass ratio of 2:0.94:0.91. The second ratio of mixed precast material was selected using a high-alkali metal vanadium oxide:conventional vanadium pentoxide:aluminum products:lime mass ratio of 1:1:0.95:1.4. The first ratio of material was added first, followed by the second ratio. A self-propagating reaction was initiated by top ignition. The reaction was stable, and the reaction flue gas was normal. After the reaction, a high-power graphite electrode was used to supplement the heat of the slag for 4 minutes. After electric heating, aluminum powder was injected into the slag for 135 seconds. After smelting, the Na₂O + Ka₂O content in the corundum slag was measured to be 0.2%. The alloy cake had an intact appearance and minimal corrosion to the furnace lining. The high-vanadium ferrometallurgical quality met the requirements of GB / T According to the requirements of Grade A of "4139-2012", the Na2O content in the corundum slag is 0.01%, the K2O content is 0.02%, the vanadium recovery rate is 98.4%, the MgO content in the slag is 8.42%, and the slag-to-gold ratio is 1.32.

[0033] Example 2 The first ratio of mixed precast material was selected using a conventional vanadium pentoxide:aluminum products:lime mass ratio of 2:0.95:0.91. The second ratio of mixed precast material was selected using a high-alkali metal vanadium oxide:conventional vanadium pentoxide:aluminum products:lime mass ratio of 0.5:1.5:0.93:1.2. The second ratio was added first, followed by the first ratio, and a self-propagating reaction was initiated by top ignition. Severe splashing and large amounts of reaction fumes were generated. After the reaction, high-power graphite electrodes were used to supplement the heat of the slag for 3 minutes. After electric heating, aluminum powder was sprayed into the slag for 125 seconds. After smelting, the Na₂O + Ka₂O content in the corundum slag was measured to be 0.7%. The alloy cake had an intact appearance and minimal corrosion of the furnace lining. The high-vanadium ferrometallurgical quality met the requirements of GB / T 4139-2012. Grade A requirements include a Na2O content of 0.01%, a K2O content of 0.01%, a vanadium recovery rate of 98%, an MgO content of 8.33%, and a slag-to-gold ratio of 1.31.

[0034] Example 3 The first ratio of mixed precast material was selected using a conventional vanadium pentoxide:aluminum products:lime mass ratio of 2:0.97:0.91. The second ratio of mixed precast material was selected using a high-alkali metal vanadium oxide:conventional vanadium pentoxide:aluminum products:lime mass ratio of 1.5:0.5:0.9:1.5. The first ratio of material was added first, followed by the second ratio. A self-propagating reaction was initiated by top ignition. The reaction involved splashing, and the reaction fumes were normal. After the reaction, a high-power graphite electrode was used to supplement the heat of the slag for 5 minutes. After electric heating, aluminum powder was sprayed into the slag for 156 seconds. After smelting, the Na₂O + Ka₂O content in the corundum slag was measured to be 0.2%. The alloy cake had an intact appearance and minimal corrosion of the furnace lining. The high-vanadium ferrometallurgical quality met the requirements of GB / T 4139-2012. Grade A requirements include a Na2O content of 0.02%, a K2O content of 0.01%, a vanadium recovery rate of 98.3%, an MgO content of 8.22%, and a slag-to-gold ratio of 1.29.

[0035] Comparative Example 1 The first ratio of mixed precast material was selected using a conventional vanadium pentoxide: aluminum product: lime mass ratio of 2:1:0.91. The second ratio of mixed precast material was selected using a high-alkali metal vanadium oxide: conventional vanadium pentoxide: aluminum product: lime mass ratio of 1:1:0.98:1.4. The first ratio of material was added first, followed by the second ratio. The reaction was initiated by top ignition and self-propagating reaction. The reaction was stable and the reaction flue gas was normal. After the reaction, the Na2O + Ka2O content in the corundum slag was measured to be 1.22%. The alloy cake was incomplete in appearance and severely corroded the furnace lining. The high vanadium iron quality met the requirements of Grade B of GB / T 4139-2012. The N2O content in the corundum slag was 2.21%, the K2O content was 1.42%, the vanadium recovery rate was 97.4%, the MgO content in the slag was 15.42%, and the slag-to-metal ratio was 1.52.

[0036] In comparison, the total Na2O+K2O content of the corundum slag in Examples 1-3 was as low as 0.03%-0.2%, far lower than the 1.22% in Comparative Example 1, and the MgO content in the slag was also lower, indicating that this method can effectively reduce the erosion of alkali metals on magnesia furnace linings.

[0037] The vanadium recovery rate of the embodiments of the present invention reaches 98.0%-98.4%, which is higher than that of Comparative Example 1 (97.4%). Furthermore, the vanadium-iron products of the embodiments all meet the Grade A requirements of GB / T 4139-2012, while Comparative Example 1 only reaches Grade B. In addition, the slag-gold ratio of the embodiments is reduced by more than 10% compared to Comparative Example 1, resulting in higher resource utilization efficiency. The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0038] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0039] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0040] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for smelting ferrovanadium from high-alkali metal vanadium oxides, characterized in that, include: S1 mixes conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form a first pre-material. It also mixes high-alkali metal vanadium oxide, conventional vanadium pentoxide, aluminum products, and lime in a certain proportion to form a second pre-material. The first pre-material is added to the bottom of the smelting furnace, and the second pre-material is added to the upper part of the smelting furnace. The furnace is then ignited at the top for self-propagating smelting. After the S2 smelting is completed, the molten slag is reheated. After S3 is heated, a reducing agent is injected into the molten slag to remove alkali, resulting in corundum slag.

2. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S1, By mass ratio, the raw material ratio of the first preform is conventional vanadium pentoxide: aluminum products: lime at a ratio of 2:(0.98-1):(0.9-0.1). The raw material ratio of the second preform is (0.5-1.5): (1.5-0.5): (0.95-1): (1.2-1.5) by mass ratio of high alkali metal vanadium oxide: conventional vanadium pentoxide: aluminum products: lime.

3. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S1, by mass percentage, the total content of Na2O and K2O in the high-alkali metal vanadium oxide is ≤8%, the content of V2O5 is ≥90%, and the particle size of the high-alkali metal vanadium oxide is less than 20mm.

4. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S2, a graphite electrode is used for supplementary heating, and the supplementary heating time is 3-6 minutes.

5. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S3, the reducing agent is aluminum powder, and the aluminum powder contains ≥98% Al by mass percentage.

6. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S3, the power source for the injection is high-pressure nitrogen gas, and the O content in the high-pressure nitrogen gas is ≤0.5% by volume percentage.

7. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, The smelting furnace is a cylindrical furnace.

8. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S1, the aluminum product is aluminum granules or aluminum shavings, wherein the particle size of the aluminum granules is 3-8 mm, the length of the aluminum shavings is no more than 10 mm, and the mass percentage content of Al in the aluminum product is ≥97%.

9. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, In S1, during the self-propagating smelting process, the maximum temperature inside the smelting furnace is controlled at 2000-2400℃, and the smelting reaction lasts for 15-25 minutes.

10. The method for smelting ferrovanadium from high-alkali metal vanadium oxides according to claim 1, characterized in that, The total content of Na2O and K2O in the corundum slag is ≤0.1%.

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