Method for extracting vanadium by roasting high-manganese vanadium slag

Abstract

The invention provides a method for extracting vanadium by roasting high-manganese vanadium slag, which comprises the following steps: (1) mixing high-manganese vanadium slag, return slag, industrial salt and sodium carbonate to obtain a mixture; the manganese content of the high-manganese vanadium slag is more than 8wt%; (2) roasting the mixture in a rotary kiln to obtain a roasted material; the roasting treatment comprises an oxidation stage at the temperature of 300-500 DEG C and a sodium modification stage at the temperature of 510-750 DEG C; and (3) the roasted material is cooled and then subjected to water leaching, and a sodium vanadate solution and tailings are obtained. Through the roasting treatment process, the occurrence of a soft melting state of the manganese element is inhibited, and the phenomena of balling and skinning in the kiln are reduced, so that the recovery rate of vanadium is improved, and the TV content in the tailings is low.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium extraction from vanadium slag, and in particular to a method for extracting vanadium by roasting high-manganese vanadium slag. Background Art

[0002] The comprehensive utilization of vanadium-titanium magnetite has great development potential, leading to the emergence of vanadium-titanium smelting in blast furnaces. However, the complex composition of vanadium-titanium magnetite creates numerous challenges for blast furnace production, hindering stable operation. To address blast furnace agglomeration and charge remelting, large amounts of manganese ore are added during production, leading to a surge in manganese content in the molten iron. This results in low-grade vanadium slag, with manganese oxide content approaching or exceeding the vanadium grade. This poses significant challenges for the subsequent roasting and extraction of vanadium pentoxide, leading to pelletization and kiln skin formation in the roasting kiln. In severe cases, pellets can form within the kiln, resulting in low vanadium conversion and high tailings TV after roasting.

[0003] CN103898329A discloses a method for extracting vanadium from manganized roasted vanadium slag. The method comprises the following steps: a) crushing the vanadium slag, mixing the crushed vanadium slag with an oxidant, and then roasting it at high temperature to obtain clinker; b) crushing the clinker, mixing the crushed clinker with water, and then adding acid for leaching to obtain a vanadium-containing leachate and vanadium-extracted tailings, wherein the oxidant is a material containing tetravalent manganese. The present invention uses a material containing high-valent manganese as an oxidant, allowing vanadium and manganese to combine during the roasting process to form a manganese vanadate compound, effectively preventing ringing of the vanadium slag during the roasting process and reducing the roasting temperature of the vanadium slag.

[0004] CN118256745A discloses a method for pre-treating and roasting high-calcium vanadium slag to extract vanadium, comprising: mixing the high-calcium vanadium slag with sulfuric acid to obtain vanadium slag A; drying and grinding the vanadium slag A to obtain vanadium slag B; oxidatively roasting the vanadium slag B at a first temperature, then heating it to a second temperature and continuing oxidative roasting, cooling it, and grinding it to obtain roasted material C; and using the roasted material C as a raw material for leaching and extracting vanadium.

[0005] CN102851507A discloses a method for sodium-roasting vanadium slag. The method comprises the following steps: mixing vanadium slag with a sodium-roasting agent to form a mixture; adding the mixture to a first roasting device and performing a primary roasting in an atmosphere with an oxygen content of 3-5% by volume to obtain a primary roasted product; adding the primary roasted product to a second roasting device at a temperature of 600-700°C and performing a secondary roasting in an atmosphere with an oxygen content of 13-21% by volume to obtain sodium-roasted clinker. The method employs two consecutive roastings in different oxidizing atmospheres to effectively control the amount of liquid phase in the material, avoid material sintering and rake tooth sticking, and improve the operating efficiency of the equipment.

[0006] However, the above-mentioned vanadium slag roasting method still has problems such as complex process flow, high roasting temperature, and the vanadium recovery rate needs to be further improved. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for extracting vanadium by roasting high-manganese vanadium slag. For high-manganese vanadium slag waste and returned slag, appropriate amounts of industrial salt and sodium carbonate are prepared, and roasting treatment is carried out in two temperature stages to achieve oxidation and sodiumization of vanadium, thereby significantly improving the recovery rate of vanadium.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for extracting vanadium by roasting high-manganese vanadium slag, which comprises the following steps:

[0010] (1) mixing high manganese vanadium slag, returned slag, industrial salt and sodium carbonate to obtain a mixture; wherein the manganese content of the high manganese vanadium slag is greater than 8wt%;

[0011] (2) The mixed material is calcined in a rotary kiln to obtain a calcined material; the calcination process includes an oxidation stage at 300-500° C. and a sodiumization stage at 510-750° C.;

[0012] (3) The calcined material is cooled and then soaked in water to obtain a sodium vanadate solution and tailings.

[0013] The method for extracting vanadium by roasting high manganese vanadium slag of the present invention is directed to extracting vanadium by roasting high manganese vanadium slag containing more than 8wt% manganese. The portion of the tailings with a higher total vanadium content after water leaching is used as returned slag, mixed with industrial salt and sodium carbonate, and then roasted in a rotary kiln. The mixture undergoes an oxidation reaction between iron and vanadium at 300-500°C to generate vanadate, and manganese and vanadate generate water-insoluble manganese vanadate. As the temperature of the rotary kiln increases, a sodiumization reaction of vanadium is performed at 510-750°C to form soluble sodium vanadate. The temperature range of 510-750°C effectively inhibits the reaction between manganese and vanadate, thereby preventing the generation of water-insoluble manganese vanadate. Furthermore, the soft melting state of manganese is prevented, which results in the manganese being wrapped into balls, leading to balling and crusting in the rotary kiln and causing difficulties in subsequent cooling and water leaching operations. The method for extracting vanadium by roasting high manganese vanadium slag of the present invention has a simple process flow, a low roasting treatment temperature, reduces the maintenance cost of rotary kiln equipment, solves the problem of accumulation of a large amount of high manganese vanadium slag, reduces environmental pollution, realizes the effective utilization of high manganese vanadium slag, and meets the requirements of green production.

[0014] The manganese content of the high manganese vanadium slag of the present invention is 8 wt% or more, for example, 8 wt%, 8.2 wt%, 8.5 wt%, 9 wt%, 10 wt%, 12 wt% or 15 wt%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0015] The calcination treatment includes an oxidation stage at 300-500°C, for example, 300°C, 350°C, 400°C, 450°C, 480°C, 490°C or 500°C, but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0016] and a sodium stage of 510 to 750° C., for example, 510° C., 520° C., 550° C., 580° C., 600° C., 650° C., 700° C. or 750° C., etc., but are not limited to the enumerated values, and other unenumerated values within this numerical range are equally applicable.

[0017] Preferably, the high manganese vanadium slag in step (1) further comprises 12 wt% to 13.63 wt% of V2O5, for example, 12 wt%, 12.2 wt%, 12.4 wt%, 12.8 wt%, 13 wt%, 13.5 wt% or 13.63 wt%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0018] 30.04 wt% to 31 wt% TFe, for example, 30.04 wt%, 30.1 wt%, 30.3 wt%, 30.5 wt%, 30.8 wt%, 30.9 wt%, or 31 wt%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0019] 1.94 wt% to 2.2 wt% CaO, for example, 1.94 wt%, 1.95 wt%, 1.98 wt%, 2 wt%, 2.05 wt%, 2.1 wt% or 2.2 wt%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0020] 14.82wt% to 15wt% SiO2, for example, it can be 14.82wt%, 14.85wt%, 14.9wt%, 14.95wt%, 14.97wt% or 15wt%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0021] Preferably, the returned slag in step (1) is a part of the tailings in step (3).

[0022] Preferably, the returned slag in step (1) comprises 0.08 wt% to 0.12 wt% of soluble vanadium, for example, 0.08 wt%, 0.09 wt%, 0.095 wt%, 0.105 wt%, 0.115 wt% or 0.12 wt%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;

[0023] and 0.5wt% to 0.8wt% of total vanadium, for example, 0.5wt%, 0.55wt%, 0.62wt%, 0.68wt%, 0.75wt% or 0.8wt%, etc., but are not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0024] The present invention preferably includes 0.08 wt% to 0.12 wt% of soluble vanadium in the returned slag. When the content of soluble vanadium is low, it indicates that the water leaching treatment effect in step (3) is poor, which will result in a reduced vanadium recovery rate.

[0025] The present invention preferably uses 0.5wt% to 0.8wt% of total vanadium as the returned slag, thereby realizing the recycling of tailings generated by water immersion treatment and further improving the recovery rate of vanadium.

[0026] Preferably, the industrial salt in step (1) comprises sodium chloride.

[0027] Preferably, the mass ratio of the high manganese vanadium slag, returned slag, industrial salt and sodium carbonate in step (1) is (60-65):(20-25):(2-3):(10-12), for example, it can be 60:20:2:10, 61:22:2:11, 62.5:21:2.3:10.7, 63:23:2.5:10.4, 64:21:2.7:11 or 65:25:3:12, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0028] The present invention preferably adopts a mass ratio of the high manganese vanadium slag, the returned slag, the industrial salt and the sodium carbonate of (60-65):(20-25):(2-3):(10-12), thereby achieving efficient recovery of vanadium from the high manganese vanadium slag and the returned slag, reducing the TV content in the tailings, reducing waste emissions and lowering environmental pollution.

[0029] Preferably, the mass content of TV in the mixture of step (1) is 4.2wt% to 4.8wt%, for example, it can be 4.2wt%, 4.3wt%, 4.45wt%, 4.55wt%, 4.7wt% or 4.8wt%, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0030] The TV in the present invention refers to the total amount of vanadium in various forms contained in the material, equivalent to the total amount of vanadium. The advantage of limiting the mass content of TV in the mixture to 4.2wt% to 4.8wt% is that it facilitates the batching of the mixture and the temperature control of the rotary kiln.

[0031] Preferably, water is added to the mixture so that the water content of the mixture is 5wt% to 6wt%, for example, it can be 5wt%, 5.2wt%, 5.35wt%, 5.5wt%, 5.75wt% or 6wt%, etc., but it is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0032] The present invention preferably adds water to the mixture to adjust the water content of the mixture to 5wt% to 6wt%, thereby reducing the generation of smoke and dust from the material and improving the fluidity of the material. By adding a specific amount of industrial salt and sodium carbonate, the temperature of the entire roasting process can be lowered, which is beneficial for the solid-phase reaction. The contact between manganese and impurities such as silicon and aluminum can also be suppressed, thereby reducing the occurrence of side reactions.

[0033] Preferably, the total time of the roasting treatment in step (2) is 3 to 5 hours, for example, it can be 3 hours, 3.3 hours, 3.7 hours, 4.2 hours, 4.6 hours or 5 hours, etc., but it is not limited to the listed time points, and other unlisted time values within the time range are also applicable.

[0034] Preferably, the calcined material in step (3) is cooled to below 500°C, for example, it can be 500°C, 480°C, 450°C, 400°C, 300°C, 200°C or 100°C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0035] Preferably, the solid-liquid ratio of the water immersion in step (3) is 1:(3-4), for example, it can be 1:3, 1:3.2, 1:3.5, 1:3.7, 1:3.9 or 1:4, etc., but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0036] The material of the rotary kiln of the present invention needs to be high temperature resistant and corrosion resistant; the material after roasting is cooled in a cooling device, which needs to have a rapid cooling function; the water immersion is carried out in a water immersion device, which needs to have good stirring and filtering functions.

[0037] As a preferred technical solution of the present invention, the method comprises the following steps:

[0038] (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of (60-65):(20-25):(2-3):(10-12) to obtain a mixture; the manganese content of the high manganese vanadium slag is 8wt% or more; the high manganese vanadium slag further comprises 12wt%-13.63wt% V2O5, 30.04wt%-31wt% TFe, 1.94wt%-2.2wt% CaO, and 14.82wt%-15wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.08wt%-0.12wt% soluble vanadium and 0.5wt%-0.8wt% total vanadium; the industrial salt comprises sodium chloride; the mass content of TV in the mixture is 4.2wt%-4.8wt%; water is added to the mixture to make the water content of the mixture 5wt%-6wt%;

[0039] (2) the mixed material is calcined in a rotary kiln for 3 to 5 hours to obtain a calcined material; the calcination process includes an oxidation stage at 300 to 500° C. and a sodiumization stage at 510 to 750° C.;

[0040] (3) After the calcined material is cooled to below 500° C., it is soaked in water at a solid-liquid ratio of 1:(3-4) to obtain a sodium vanadate solution and tailings.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] (1) The method for extracting vanadium by roasting high manganese vanadium slag provided by the present invention prolongs the sodium stage time, optimizes the roasting process, inhibits the soft melting state of manganese element, reduces the formation of manganese vanadate, reduces the balling and crusting phenomenon in the kiln, thereby improving the vanadium recovery rate and reducing the TV content in the tailings;

[0043] (2) The method for extracting vanadium by roasting high manganese vanadium slag provided by the present invention effectively utilizes high manganese vanadium slag and returned slag, reduces waste discharge, reduces environmental pollution, and meets the requirements of green production.

[0044] (3) The method for extracting vanadium by roasting high manganese vanadium slag provided by the present invention can be implemented on the basis of existing equipment without the need for additional investment, while improving the recovery rate of vanadium and having significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a process flow chart of the method for extracting vanadium by roasting high manganese vanadium slag provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0047] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0048] Example 1

[0049] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag, and its process flow chart is as follows: Figure 1 The method comprises the following steps:

[0050] (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of 63:25:2:10, placing the mixture in a mixer and mixing evenly to obtain a mixture; the manganese content of the high manganese vanadium slag is 8%; the high manganese vanadium slag further comprises 13.63wt% V2O5, 30.04wt% TFe, 1.94wt% CaO and 14.82wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.1wt% soluble vanadium and 0.55wt% total vanadium; the industrial salt is sodium chloride; the mass content of TV in the mixture is 4.5wt%; water is added to the mixture to make the water content of the mixture 5.2wt%;

[0051] (2) The mixed material is fed into a metering bin through an elevator and then fed into a rotary kiln for calcination for 4 hours to obtain a calcined material; the calcination process includes an oxidation stage at 400°C and a sodiumization stage at 700°C;

[0052] (3) After the calcined material is cooled to 400° C., it is soaked in water at a solid-liquid ratio of 1:3 to obtain a sodium vanadate solution and tailings.

[0053] In this embodiment, the recovery rate of vanadium is 85%, and the TV content in the tailings is 0.70%.

[0054] Example 2

[0055] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag, the method comprising the following steps:

[0056] (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of 62:25:2.5:10.5, placing the mixture in a mixer and mixing evenly to obtain a mixture; the manganese content of the high manganese vanadium slag is 10%; the high manganese vanadium slag further comprises 13.63wt% V2O5, 30.04wt% TFe, 1.94wt% CaO and 14.82wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.08wt% soluble vanadium and 0.8wt% total vanadium; the industrial salt is sodium chloride; the mass content of TV in the mixture is 4.3wt%; water is added to the mixture to make the water content of the mixture 5.4wt%;

[0057] (2) The mixed material is fed into a metering bin through an elevator and then fed into a rotary kiln for calcination for 4 hours to obtain a calcined material; the calcination process includes an oxidation stage at 300-500°C and a sodiumization stage at 510-750°C;

[0058] (3) After the calcined material is cooled to 480° C., it is soaked in water at a solid-liquid ratio of 1:(3-4) to obtain a sodium vanadate solution and tailings.

[0059] In this embodiment, the vanadium recovery rate is 86%, and the TV content in the tailings is 0.65%.

[0060] Example 3

[0061] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag, the method comprising the following steps:

[0062] (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of 60:20:3:10, placing the mixture in a mixer and mixing evenly to obtain a mixture; the manganese content of the high manganese vanadium slag is 11%; the high manganese vanadium slag further comprises 12wt% V2O5, 31wt% TFe, 2wt% CaO and 15wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.088wt% soluble vanadium and 0.5wt% total vanadium; the industrial salt is sodium chloride; the mass content of TV in the mixture is 4.8wt%; water is added to the mixture to make the water content of the mixture 5wt%;

[0063] (2) The mixed material is fed into a metering bin through an elevator for metering and then enters a rotary kiln for roasting for 3 hours to obtain a roasted material; the roasting process includes an oxidation stage at 300°C and a sodiumization stage at 510°C;

[0064] (3) After the calcined material is cooled to 380° C., it is soaked in water at a solid-liquid ratio of 1:3.4 to obtain a sodium vanadate solution and tailings.

[0065] In this embodiment, the recovery rate of vanadium is 86.4%, and the TV content in the tailings is 0.6%.

[0066] Example 4

[0067] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag, the method comprising the following steps:

[0068] (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of 65:21:2:12, placing the mixture in a mixer and mixing evenly to obtain a mixture; the manganese content of the high manganese vanadium slag is 8.9%; the high manganese vanadium slag further comprises 13wt% V2O5, 30.07wt% TFe, 2.2wt% CaO and 14.9wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.12wt% soluble vanadium and 0.5wt% total vanadium; the industrial salt is sodium chloride; the mass content of TV in the mixture is 4.2wt%; water is added to the mixture to make the water content of the mixture 6wt%;

[0069] (2) The mixed material is fed into a metering bin through an elevator for metering and then enters a rotary kiln for roasting for 5 hours to obtain a roasted material; the roasting process includes an oxidation stage at 500°C and a sodiumization stage at 750°C;

[0070] (3) After the calcined material is cooled to 500° C., it is soaked in water at a solid-liquid ratio of 1:4 to obtain a sodium vanadate solution and tailings.

[0071] In this embodiment, the recovery rate of vanadium is 85.2%, and the TV content in the tailings is 0.6%.

[0072] Example 5

[0073] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag. The method is the same as that of Example 1 except that the mass ratio of high manganese vanadium slag, returned slag, industrial salt and sodium carbonate is 63:25:1:10.

[0074] Example 6

[0075] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag. The method is the same as that of Example 1 except that the mass ratio of high manganese vanadium slag, returned slag, industrial salt and sodium carbonate is 63:25:4:10.

[0076] From Example 1 and Examples 5 to 6, it can be seen that in Example 5, due to the lower quality of industrial salt sodium chloride, the vanadium conversion rate is low and the manganese interference is enhanced; in Example 6, due to the higher quality of industrial salt sodium chloride, the vanadium recovery rate is also reduced.

[0077] Example 7

[0078] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag. The method is the same as that of Example 1 except that the mass ratio of high manganese vanadium slag, returned slag, industrial salt and sodium carbonate is 63:25:2:8.

[0079] Example 8

[0080] This embodiment provides a method for extracting vanadium by roasting high manganese vanadium slag. The method is the same as that of Example 1 except that the mass ratio of high manganese vanadium slag, returned slag, industrial salt and sodium carbonate is 63:25:2:14.

[0081] From Example 1 and Examples 7 to 8, it can be seen that in Example 7, due to the lower quality of sodium carbonate, insufficient vanadium fixation will result, impurities will compete for reaction, and thus the vanadium recovery rate will be reduced; in Example 8, due to the higher quality of sodium carbonate, the cost of vanadium extraction will increase and sintering risk will be generated.

[0082] Comparative Example 1

[0083] This comparative example provides a method for extracting vanadium by roasting high-manganese vanadium slag. The method is the same as Example 1 except that the temperature in the oxidation stage is 280°C.

[0084] In this comparative example, due to the low temperature in the oxidation stage, the utilization rate of the sodium salt decreased and the interference of impurities increased, which led to a significant decrease in the vanadium recovery rate.

[0085] Comparative Example 2

[0086] This comparative example provides a method for extracting vanadium by roasting high manganese vanadium slag. The method is the same as Example 1 except that the temperature in the sodiumization stage is 780°C.

[0087] In this comparative example, due to the high temperature in the sodium stage, the manganese element exhibits a soft melting ball phenomenon, which is not conducive to the sodium reaction. The formation of dense material is not conducive to the precipitation of vanadium during water immersion, which leads to a high TV content in the tailings and a significant reduction in the vanadium recovery rate.

[0088] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for extracting vanadium by roasting high manganese vanadium slag, characterized in that: The method comprises the following steps: (1) mixing high manganese vanadium slag, returned slag, industrial salt and sodium carbonate to obtain a mixture; wherein the manganese content of the high manganese vanadium slag is greater than 8wt%; (2) The mixed material is calcined in a rotary kiln to obtain a calcined material; the calcination process includes an oxidation stage at 300-500° C. and a sodiumization stage at 510-750° C.; (3) The calcined material is cooled and then soaked in water to obtain a sodium vanadate solution and tailings.

2. The method according to claim 1, characterized in that In terms of mass percentage, the high manganese vanadium slag in step (1) further comprises 12 wt% to 13.63 wt% of V2O5, 30.04 wt% to 31 wt% of TFe, 1.94 wt% to 2.2 wt% of CaO, and 14.82 wt% to 15 wt% of SiO2.

3. The method according to claim 1 or 2, characterized in that The returned slag in step (1) is a part of the tailings in step (3); Preferably, the returned slag comprises 0.08 wt% to 0.12 wt% of soluble vanadium and 0.5 wt% to 0.8 wt% of total vanadium.

4. The method according to any one of claims 1 to 3, characterized in that The industrial salt in step (1) includes sodium chloride.

5. The method according to any one of claims 1 to 4, characterized in that The mass ratio of the high manganese vanadium slag, returned slag, industrial salt and sodium carbonate in step (1) is (60-65):(20-25):(2-3):(10-12).

6. The method according to any one of claims 1 to 5, characterized in that The mass content of TV in the mixture of step (1) is 4.2wt% to 4.8wt%; Preferably, water is added to the mixture so that the water content of the mixture is 5 wt % to 6 wt %.

7. The method according to any one of claims 1 to 6, characterized in that The total time of the roasting treatment in step (2) is 3 to 5 hours.

8. The method according to any one of claims 1 to 7, characterized in that After the calcination in step (3), the material is cooled to below 500°C.

9. The method according to any one of claims 1 to 8, characterized in that The solid-liquid ratio of the water immersion in step (3) is 1:(3-4).

10. The method according to any one of claims 1 to 9, characterized in that The method comprises the following steps: (1) mixing high manganese vanadium slag, return slag, industrial salt and sodium carbonate in a mass ratio of (60-65):(20-25):(2-3):(10-12) to obtain a mixture; the manganese content of the high manganese vanadium slag is 8wt% or more; the high manganese vanadium slag further comprises 12wt%-13.63wt% V2O5, 30.04wt%-31wt% TFe, 1.94wt%-2.2wt% CaO, and 14.82wt%-15wt% SiO2; the return slag is a part of the tailings in step (3); the return slag comprises 0.08wt%-0.12wt% soluble vanadium and 0.5wt%-0.8wt% total vanadium; the industrial salt comprises sodium chloride; the mass content of TV in the mixture is 4.2wt%-4.8wt%; water is added to the mixture to make the water content of the mixture 5wt%-6wt%; (2) the mixed material is calcined in a rotary kiln for 3 to 5 hours to obtain a calcined material; the calcination process includes an oxidation stage at 300 to 500° C. and a sodiumization stage at 510 to 750° C.; (3) After the calcined material is cooled to below 500° C., it is soaked in water at a solid-liquid ratio of 1:(3-4) to obtain a sodium vanadate solution and tailings.

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