A method for preparing vanadium trioxide by using vanadium-containing leaching solution short process

Abstract

The present application relates to the technical field of hydrometallurgy, and provides a method for preparing vanadium trioxide by using vanadium-containing leaching solution, in which the tetravalent vanadium in the vanadium-containing leaching solution is oxidized to pentavalent vanadium, then the pH value is adjusted to 4-6, and vanadium trioxide slurry is obtained through two reduction reactions; the vanadium trioxide slurry is subjected to wet magnetic separation, the tailing slurry obtained through the magnetic separation is subjected to solid-liquid separation and then dried to obtain vanadium trioxide. The present application greatly simplifies the preparation process of vanadium trioxide by using vanadium-containing leaching solution as raw material to carry out liquid-phase hydrogen reduction vanadium precipitation; the present application uses nickel powder and nickel sulfate as catalysts for catalysis in batches, which can effectively reduce the preparation cost of vanadium trioxide, and the vanadium precipitation product is easy to separate by magnetic separation, and the purity of the obtained vanadium trioxide product is greater than or equal to 99.5%. In summary, the method provided by the present application has the advantages of short process, low cost and high product purity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and particularly relates to a method for preparing vanadium trioxide by using vanadium-containing leaching solution short process. BACKGROUND

[0002] Vanadium trioxide is an important raw material for preparing vanadium-iron alloy, vanadium nitride alloy and other alloy materials. At present, reduction roasting is the mainstream process for preparing vanadium trioxide. The general method is to pass reducing gas into a push plate kiln for high-temperature roasting, which has the advantages of large processing capacity, high reaction efficiency and simple operation. However, the reaction temperature of the reduction roasting process is generally higher than 600℃, which has high energy consumption and increases carbon emissions. At the same time, the raw materials used in reduction roasting are mainly ammonium metavanadate, vanadium pentoxide and other precursors. These precursors need to be prepared through a complex process of "vanadium-containing leaching solution extraction, stripping, ammonium salt vanadium precipitation, filtration, calcination", etc. Therefore, a large amount of ammonia-nitrogen wastewater and waste gas will be generated. This leads to high pollution treatment cost and difficulty in meeting environmental protection requirements, which seriously restricts the green and sustainable development of the vanadium extraction industry.

[0003] Therefore, liquid phase hydrogen reduction technology is introduced to overcome the shortcomings of high energy consumption, large carbon emissions, long process and heavy pollution of reduction roasting. Zhang Guobin et al. (doi:10.3390 / min7100182) used liquid phase hydrogen reduction technology to prepare vanadium trioxide product by using palladium chloride as catalyst, and the rich vanadium liquid was reacted at a reaction temperature of 250℃ and a hydrogen partial pressure of 4MPa for 2h. Although this study reduces the roasting temperature and eliminates ammonia-nitrogen pollution, the catalyst used is palladium chloride, which is expensive (>1500 ￥ / g) and difficult to recover. At the same time, the rich vanadium liquid is obtained after "vanadium-containing leaching solution N235 extraction-stripping", which reduces the processes of vanadium precipitation and calcination, but the process is still relatively long.

[0004] In Chinese patent CN114132962A, nickel powder is used as a catalyst to achieve good catalytic effect. After liquid phase hydrogen reduction and magnetic separation, the purity of the final vanadium trioxide product is about 99.2%. However, the raw materials used in this patent are vanadium pentoxide powder, sodium orthovanadate powder, sodium metavanadate powder or sodium pyrovanadate powder. The preparation of these raw materials still needs to go through a complex process of "vanadium-containing leaching solution extraction, stripping, ammonium salt vanadium precipitation, filtration, calcination", etc. Therefore, the problems of ammonia-nitrogen pollution and complex process have not been solved. At the same time, it is found through experiments that nickel powder will play a "seed" role in the process of liquid phase hydrogen reduction, i.e. a large amount of vanadium precipitation products will be wrapped around the nickel powder particles. Therefore, in the subsequent magnetic separation process, even under a relatively high magnetic field strength (8-13kOe), it is difficult to achieve an ideal separation effect of vanadium and nickel, which will affect the purity of the final vanadium trioxide product.

[0005] In summary, the current liquid phase hydrogen reduction technology still has problems such as long process and low product purity, and it is urgent to provide a vanadium trioxide preparation method with short process, low cost and high product purity. SUMMARY

[0006] Therefore, the application provides a method for preparing vanadium trioxide by using vanadium-containing leaching solution with short process.

[0007] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0008] A method for preparing vanadium trioxide by using vanadium-containing leaching solution with short process, comprising the following steps:

[0009] (1) Oxidizing vanadium (IV) in the vanadium-containing leaching solution to vanadium (V) by using an oxidizing agent, and then adjusting the pH value to 4-6 to obtain a feed liquid; the vanadium concentration of the feed liquid is >5g / L;

[0010] (2) Mixing the feed liquid and nickel powder, and performing a first reduction reaction under hydrogen condition to obtain a primary slurry;

[0011] (3) Mixing the primary slurry and nickel sulfate, and performing a second reduction reaction under hydrogen condition to obtain a vanadium trioxide slurry;

[0012] (4) Performing wet magnetic separation on the vanadium trioxide slurry to obtain a magnetic separation concentrate slurry and a magnetic separation tailing slurry; sequentially performing solid-liquid separation and drying on the magnetic separation tailing slurry to obtain vanadium trioxide.

[0013] Preferably, the vanadium-containing leaching solution is one or more of vanadium shale leaching solution, vanadium-containing steel slag leaching solution, waste vanadium catalyst leaching solution, vanadium-titanium magnetite leaching solution and clay vanadium ore leaching solution.

[0014] The pH value of the vanadium-containing leaching solution is -0.5-3; the vanadium concentration of the vanadium-containing leaching solution is ≥6.0g / L, the phosphorus concentration is ≤1.0g / L, the iron concentration is ≤1.8g / L, and the silicon concentration is ≤1.0g / L.

[0015] Preferably, the oxidizing agent is one or more of sodium chlorate, potassium chlorate, perchloric acid, chloric acid, hypochlorous acid, hydrogen peroxide, sodium perchlorate, potassium perchlorate, sodium hypochlorite and potassium hypochlorite.

[0016] Preferably, the first reduction reaction is carried out in an autoclave; the filling rate of the autoclave is 40% to 60%; the amount of the nickel powder is 1 to 3 g / L; the temperature of the first reduction reaction is 250 to 300℃, the reaction time is 0.5 to 2 h, the hydrogen partial pressure is 3 to 6 MPa, and the first reduction reaction is carried out under stirring at a stirring speed of 300 to 600 r / min.

[0017] Preferably, the content of elemental nickel in the nickel powder is ≥ 99.5 wt%, and the particle size of the nickel powder is less than 0.037 mm.

[0018] Preferably, the second reduction reaction is carried out in an autoclave; the filling rate of the autoclave is 40% to 60%; the amount of the nickel sulfate is 15 to 25 g / L; the temperature of the second reduction reaction is 250 to 300℃, the time is 1.5 to 3 h, and the hydrogen partial pressure is 3 to 6 MPa; and the first reduction reaction is carried out under stirring at a stirring speed of 300 to 600 r / min.

[0019] Preferably, the nickel sulfate is one or both of anhydrous nickel sulfate and nickel sulfate hexahydrate; and the purity of the nickel sulfate is ≥ 99 wt%.

[0020] Preferably, the wet magnetic separation is a wet high-gradient magnetic separation; the magnetic field strength of the wet magnetic separation is 2 to 10 kOe; and the diameter of the magnetic medium wire is 1.5 to 3 mm.

[0021] Preferably, after obtaining the magnetic concentrate slurry, the magnetic concentrate slurry is subjected to solid-liquid separation, and the obtained solid is dried and returned to step (2).

[0022] Preferably, after the magnetic tailing slurry is subjected to solid-liquid separation, the obtained alkali liquor is concentrated and returned to step (1) for recycling.

[0023] The present application provides a method for preparing vanadium trioxide by a short process using vanadium-containing leaching solution, which comprises the following steps: (1) oxidizing tetravalent vanadium in the vanadium-containing leaching solution to pentavalent vanadium by using an oxidizing agent, and then adjusting the pH value to 4 to 6 to obtain an input liquid; the vanadium concentration of the input liquid is > 5 g / L; (2) mixing the input liquid and nickel powder, and carrying out a first reduction reaction under hydrogen to obtain a primary slurry; (3) mixing the primary slurry and nickel sulfate, and carrying out a second reduction reaction under hydrogen to obtain a vanadium trioxide slurry; and (4) carrying out wet magnetic separation on the vanadium trioxide slurry to obtain a magnetic concentrate slurry and a magnetic tailing slurry; and sequentially subjecting the magnetic tailing slurry to solid-liquid separation and drying to obtain vanadium trioxide. The present application uses vanadium-containing leaching solution as raw material to carry out liquid-phase hydrogen reduction vanadium precipitation, completely eliminating the complicated processes such as "extraction, stripping, ammonium salt vanadium precipitation, filtration, and calcination" of the vanadium-containing leaching solution, and greatly simplifying the preparation process of vanadium trioxide.

[0024] The present application uses nickel powder as the catalyst for the first reduction reaction and nickel sulfate as the catalyst for the second reduction reaction to carry out liquid-phase hydrogen reduction of vanadium precipitation, and compared with the price of palladium chloride, more than 9000 yuan per ton of vanadium trioxide product can be saved; and compared with the price of using nickel powder as the catalyst alone, more than 1000 yuan per ton of vanadium trioxide product can be saved. Therefore, the method of using nickel powder and nickel sulfate as catalysts for catalysis in batches effectively reduces the preparation cost of vanadium trioxide.

[0025] In addition, the vanadium precipitation rate of the primary slurry in step (2) has already exceeded 99.5%, which can effectively prevent most of the catalyst surface from being wrapped by the vanadium precipitation product, and the added secondary catalyst (i.e. nickel sulfate) is used to activate hydrogen, and the activated hydrogen is used to reduce the vanadium precipitation product to prepare vanadium trioxide. Therefore, in the subsequent magnetic separation process, since the vanadium precipitation product is not wrapped around the catalyst, a lower magnetic field strength can achieve a better vanadium-nickel separation effect, and the final vanadium trioxide product has a purity of ≥99.5%.

[0026] In summary, the method provided by the present application has the advantages of short process, low cost and high product purity. DETAILED DESCRIPTION

[0027] The present application provides a method for preparing vanadium trioxide by using a vanadium-containing leaching solution in a short process, which comprises the following steps:

[0028] (1) using an oxidizing agent to oxidize tetravalent vanadium in the vanadium-containing leaching solution to pentavalent vanadium, and then adjusting the pH value to 4-6 to obtain an input liquid; the vanadium concentration of the input liquid is >5 g / L;

[0029] (2) mixing the input liquid and nickel powder, and carrying out a first reduction reaction under hydrogen to obtain a primary slurry;

[0030] (3) mixing the primary slurry and nickel sulfate, and carrying out a second reduction reaction under hydrogen to obtain a vanadium trioxide slurry;

[0031] (4) carrying out wet magnetic separation on the vanadium trioxide slurry to obtain a magnetic separation concentrate slurry and a magnetic separation tailing slurry; sequentially carrying out solid-liquid separation and drying on the magnetic separation tailing slurry to obtain vanadium trioxide.

[0032] The present application adopts an oxidant to oxidize the tetravalent vanadium in the vanadium-containing leaching solution to pentavalent vanadium, and then adjusts the pH value to 4-6 to obtain a feed liquid; the vanadium concentration of the feed liquid is >5g / L. In the present application, the vanadium-containing leaching solution is preferably one or more of vanadium shale leaching solution, vanadium-containing steel slag leaching solution, waste vanadium catalyst leaching solution, vanadium-titanium magnetite leaching solution and clay vanadium ore leaching solution; the pH value of the vanadium-containing leaching solution is preferably -0.5-3; the vanadium concentration of the vanadium-containing leaching solution is preferably ≥6.0g / L, more preferably 6-45g / L, the phosphorus concentration is preferably ≤1.0g / L, more preferably ≤0.5g / L, the iron concentration is preferably ≤1.8g / L, more preferably ≤1.5g / L, and the silicon concentration is preferably ≤1.0g / L, more preferably ≤0.5g / L. In the present application, the vanadium in the vanadium-containing leaching solution exists in the form of VO 2+ .

[0033] In the present application, the oxidant is preferably one or more of sodium chlorate, potassium chlorate, perchloric acid, chloric acid, hypochlorous acid, hydrogen peroxide, sodium perchlorate, potassium perchlorate, sodium hypochlorite and potassium hypochlorite. The present application adopts an oxidant to completely oxidize the tetravalent vanadium in the vanadium-containing leaching solution to pentavalent vanadium, and the present application does not have special requirements for the amount of the oxidant, which can completely oxidize the tetravalent vanadium in the vanadium-containing leaching solution.

[0034] In the present application, the reagent for adjusting the pH value is preferably sodium hydroxide solution, and the pH value of the system is preferably adjusted to 4.5-5.5; the present application does not have special requirements for the concentration of the sodium hydroxide solution, which can adjust the pH value of the system to the above range.

[0035] In the present application, the vanadium concentration of the feed liquid is >5g / L, more preferably 6-45g / L.

[0036] After obtaining the feed liquid, the present application mixes the feed liquid with nickel powder, and carries out a first reduction reaction under hydrogen condition to obtain a primary slurry. In the present application, the content of elemental nickel in the nickel powder is preferably ≥ 99.5wt%, and the particle size of the nickel powder is preferably less than 0.037mm. In the present application, the first reduction reaction is preferably carried out in an autoclave; the filling rate of the autoclave is preferably 40% to 60%, more preferably 45% to 55%, and the filling rate of the autoclave specifically refers to the percentage of the volume of liquid to the volume of the autoclave. In the present application, the amount of the nickel powder is preferably 1 to 3g / L, more preferably 1.5 to 2.5g / L (i.e. the amount of nickel powder added per liter of feed liquid); the temperature of the first reduction reaction is preferably 250 to 300℃, more preferably 260 to 280℃, the time of the first reduction reaction is preferably 0.5 to 2h, more preferably 1 to 1.5h, the hydrogen partial pressure of the first reduction reaction is preferably 3 to 6MPa, more preferably 4 to 5MPa, and the first reduction reaction is preferably carried out under stirring condition, and the stirring speed is preferably 300 to 600r / min. The main reactions occurring during the first reduction reaction are as follows:

[0037] 3HV 10 O 28 5- +10Na + +5H + +11H2O=5Na2V6O 16 ·3H2O(↓)

[0038] 2Na2V6O 16 ·3H2O+3H2+2OH - +2Na + =6Na(V2O5)+7H2O

[0039] After the first reduction reaction is completed, the autoclave is cooled and depressurized to obtain the primary slurry.

[0040] After obtaining the primary slurry, the primary slurry is mixed with nickel sulfate, and a second reduction reaction is carried out under hydrogen to obtain a vanadium trioxide slurry. In the present application, the nickel sulfate is preferably one or both of anhydrous nickel sulfate and nickel sulfate hexahydrate; the purity of the nickel sulfate is preferably ≥ 99wt%; the second reduction reaction is preferably carried out in an autoclave, the filling rate of the autoclave is preferably 40% to 60%, more preferably 45% to 55%; the amount of nickel sulfate used is preferably 15 to 25 g / L (i.e. the amount of nickel sulfate added per liter of primary slurry); the temperature of the second reduction reaction is preferably 250 to 300°C, more preferably 260 to 280°C; the time of the second reduction reaction is preferably 1.5 to 3 hours, more preferably 2 to 2.5 hours; the hydrogen partial pressure of the second reduction reaction is preferably 3 to 6 MPa, more preferably 4 to 5 MPa; the second reduction reaction is preferably carried out under stirring, and the stirring speed is preferably 300 to 600 r / min. The main reactions occurring during the second reduction reaction are as follows:

[0041] 2Na(V2O5) + 3H2 + 2H2O = 4VO2(H2O) 0.5 + 2Na + + 2OH -

[0042] 2VO2(H2O) 0.5 + H2 = V2O3 + 2H2O

[0043] After the second reduction reaction is completed, the autoclave is cooled and depressurized to obtain a vanadium trioxide slurry.

[0044] After obtaining the vanadium trioxide slurry, the vanadium trioxide slurry is subjected to wet magnetic separation to obtain a magnetic concentrate slurry and a magnetic tailings slurry; the magnetic tailings slurry is sequentially subjected to solid-liquid separation and drying to obtain vanadium trioxide. In the present application, the wet magnetic separation is preferably wet high gradient magnetic separation; the magnetic field strength of the wet magnetic separation is preferably 2 to 10 kOe, more preferably 2 kOe, 5 kOe or 7 kOe, and the magnetic medium wire diameter is preferably 1.5 to 3 mm.

[0045] The application has no special requirements for the method of solid-liquid separation and drying of the magnetic separation tailings slurry, and conditions well known to those skilled in the art can be used; the solid and the alkali liquor are obtained after the solid-liquid separation of the magnetic separation tailings slurry (the reaction process continuously releases hydroxyl ions, resulting in an increase in the pH value of the solution to about 13), the solid is vanadium trioxide, and the purity of the vanadium trioxide is ≥ 99.5%; the alkali liquor is preferably concentrated and then returned to step (1) for recycling, specifically, the alkali liquor is returned to step (1) to replace the sodium hydroxide solution; the main components of the alkali liquor are sodium hydroxide and sulfate, and the application returns the concentrated alkali liquor to step (1) for adjusting the pH value of the vanadium-containing leaching liquor, so that new NaOH does not need to be added subsequently, which is conducive to further reducing the cost.

[0046] After obtaining the magnetic separation concentrate slurry, the application preferably performs solid-liquid separation on the magnetic separation concentrate slurry, dries the obtained solid, and returns the solid to step (2), specifically, the solid is returned to step (2) to replace the nickel powder; the main components in the solid are metallic nickel and a small amount of vanadium trioxide, and the application returns the solid to step (2), which can realize the recycling of the nickel powder and reduce the cost of the catalyst.

[0047] The technical solutions in the application will be clearly and completely described below in combination with the embodiments in the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0048] Embodiment 1

[0049] A method for preparing vanadium trioxide by using a vanadium-containing leaching liquor in a short process, steps are as follows:

[0050] (1) Vanadium shale leaching liquor is used as raw material, the initial pH value of the vanadium shale leaching liquor is -0.5, the vanadium concentration is 6.0 g / L, the phosphorus concentration is 0.8 g / L, the iron concentration is 1.2 g / L, and the silicon concentration is 0.7 g / L; sodium hypochlorite is used to completely oxidize tetravalent vanadium in the vanadium shale leaching liquor to pentavalent vanadium, and then sodium hydroxide solution is used to adjust the pH value to 4.5, to obtain an inlet liquid with a vanadium concentration of 5.6 g / L.

[0051] (2) The inlet liquid is placed in an autoclave, and nickel powder is added as a catalyst; under the conditions of an autoclave filling rate of 40%, a nickel powder dosage of 1 g / L, a temperature of 250°C, a hydrogen partial pressure of 3 MPa, and a stirring speed of 400 r / min, a first reduction reaction is performed for 0.5 h, and after cooling and pressure release, a primary slurry is obtained.

[0052] (3) adding anhydrous nickel sulfate into the primary slurry, and performing a second reduction reaction under the conditions of a high-pressure kettle filling rate of 40%, an anhydrous nickel sulfate dosage of 15 g / L, a temperature of 250°C, a hydrogen partial pressure of 3 MPa, and a stirring speed of 400 r / min for 1.5 h, and then obtaining a vanadium trioxide slurry after cooling and pressure release;

[0053] (4) performing wet high-gradient magnetic separation on the vanadium trioxide slurry under the conditions of a magnetic field strength of 2 kOe and a magnetic medium wire of 3 mm, and obtaining a magnetic separation concentrate slurry and a magnetic separation tailings slurry; obtaining a vanadium trioxide product after solid-liquid separation and vacuum drying of the magnetic separation tailings slurry; concentrating the alkali liquor obtained by solid-liquid separation of the magnetic separation tailings slurry and returning it to step (1) for recycling; and performing solid-liquid separation on the magnetic separation concentrate slurry, drying the obtained solid, and returning it to step (2) for recycling.

[0054] In the embodiment, the nickel recovery rate is 99.8%, the vanadium precipitation rate is 99.6%, and the purity of vanadium trioxide is 99.6%; wherein the nickel recovery rate is the percentage of the content of nickel in the solid obtained by solid-liquid separation of the magnetic separation concentrate to the total amount of nickel in step (2); and the vanadium precipitation rate is the percentage of the content of vanadium in the obtained vanadium trioxide product to the content of vanadium in the vanadium-containing leaching solution.

[0055] Example 2

[0056] A method for preparing vanadium trioxide by using a vanadium-containing leaching solution in a short process, the steps being as follows:

[0057] (1) using a vanadium-containing steel slag leaching solution as a raw material, the initial pH value of the vanadium-containing steel slag leaching solution being 0.8, the vanadium concentration being 13.3 g / L, the phosphorus concentration being 0.1 g / L, the iron concentration being 1.8 g / L, and the silicon concentration being 0.1 g / L, completely oxidizing tetravalent vanadium in the vanadium-containing steel slag leaching solution into pentavalent vanadium by using sodium chlorate, and then adjusting the pH value to 5.5 by using a sodium hydroxide solution to obtain a feed liquid with a vanadium concentration of 12.8 g / L;

[0058] (2) placing the feed liquid in a high-pressure kettle, using nickel powder as a catalyst, performing a first reduction reaction under the conditions of a high-pressure kettle filling rate of 50%, a nickel powder dosage of 2 g / L, a temperature of 280°C, a hydrogen partial pressure of 4 MPa, and a stirring speed of 300 r / min for 1 h, and then obtaining a primary slurry after cooling and pressure release;

[0059] (3) adding anhydrous nickel sulfate into the primary slurry, and performing a second reduction reaction under the conditions of a high-pressure kettle filling rate of 40%, an anhydrous nickel sulfate dosage of 15 g / L, a temperature of 250°C, a hydrogen partial pressure of 3 MPa, and a stirring speed of 400 r / min for 1.5 h, and then obtaining a vanadium trioxide slurry after cooling and pressure release;

[0060] (4) The vanadium trioxide slurry is subjected to wet high gradient magnetic separation under the conditions of a magnetic field strength of 5 kOe and a magnetic medium wire of 2.0 mm to obtain a magnetic separation concentrate slurry and a magnetic separation tailing slurry; the magnetic separation tailing slurry is subjected to solid-liquid separation and vacuum drying to obtain a vanadium trioxide product; the alkali liquor obtained by solid-liquid separation of the magnetic separation tailing slurry is concentrated and returned to step (1) for recycling, and the magnetic separation concentrate slurry is subjected to solid-liquid separation, and the obtained solid is dried and returned to step (2) for recycling.

[0061] In this embodiment, the nickel recovery rate is 99.5%, the vanadium precipitation rate is 99.8%, and the purity of vanadium trioxide is 99.5%.

[0062] Example 3

[0063] A method for preparing vanadium trioxide by a short process using vanadium-containing leaching solution, the steps are as follows:

[0064] (1) Using clay vanadium ore leaching solution as raw material, the initial pH value of the clay vanadium ore leaching solution is 3, the vanadium concentration is 35.8 g / L, the phosphorus concentration is 1.0 g / L, the iron concentration is 0.6 g / L, and the silicon concentration is 1.0 g / L, hydrogen peroxide is used to completely oxidize tetravalent vanadium in the clay vanadium ore leaching solution to pentavalent vanadium, and then sodium hydroxide solution is used to adjust the pH value to 6 to obtain a feed liquid with a vanadium concentration of 30.5 g / L;

[0065] (2) The feed liquid is placed in an autoclave, and nickel powder is used as a catalyst to perform a first reduction reaction under the conditions of an autoclave filling rate of 60%, a nickel powder dosage of 3 g / L, a temperature of 300°C, a hydrogen partial pressure of 6 MPa, and a stirring speed of 600 r / min for 2 h, and then cooled and depressurized to obtain a primary slurry;

[0066] (3) Anhydrous nickel sulfate is added to the primary slurry, and a second reduction reaction is performed under the conditions of an autoclave filling rate of 60%, a nickel sulfate dosage of 25 g / L, a temperature of 260°C, a hydrogen partial pressure of 6 MPa, and a stirring speed of 600 r / min for 3 h, and then cooled and depressurized to obtain a vanadium trioxide slurry;

[0067] (4) The vanadium trioxide slurry is subjected to wet high gradient magnetic separation under the conditions of a magnetic field strength of 10 kOe and a magnetic medium wire of 1.5 mm to obtain a magnetic separation concentrate slurry and a magnetic separation tailing slurry; the magnetic separation tailing slurry is subjected to solid-liquid separation and vacuum drying to obtain a vanadium trioxide product; the alkali liquor obtained by solid-liquid separation of the magnetic separation tailing slurry is concentrated and returned to step (1) for recycling, and the magnetic separation concentrate slurry is subjected to solid-liquid separation, and the obtained solid is dried and returned to step (2) for recycling.

[0068] In this embodiment, the nickel recovery rate is 99.4%, the vanadium precipitation rate is 99.5%, and the purity of vanadium trioxide is 99.7%.

[0069] Comparative Example 1

[0070] Step (1): same as example 1;

[0071] Step (2): the feed liquid is placed in an autoclave, and reduction reaction is carried out under the conditions of 60% autoclave filling rate, 3g / L nickel powder, 260℃ reaction temperature, 4MPa hydrogen partial pressure, and 300r / min stirring speed, using nickel powder as catalyst, for 2h, and then the primary slurry is obtained after cooling and pressure release.

[0072] Step (3): the primary slurry is directly subjected to wet high gradient magnetic separation under the conditions of 2kOe magnetic field intensity and 3mm magnetic medium wire, to obtain magnetic separation concentrate slurry and magnetic separation tailings slurry; the magnetic separation tailings slurry is subjected to solid-liquid separation and vacuum drying to obtain vanadium trioxide product; the alkali liquor obtained by solid-liquid separation of the magnetic separation tailings slurry is concentrated and returned to step (1) for recycling, and the magnetic separation concentrate slurry is subjected to solid-liquid separation, and the obtained solid is dried and returned to step (2) for recycling.

[0073] It is calculated that the vanadium precipitation rate is 99.6%, the magnetic separation recovery rate of nickel powder is 85.4%, and the purity of vanadium trioxide is 72.1%.

[0074] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for preparing vanadium trioxide using a short-process vanadium-containing leaching solution, characterized in that, Includes the following steps: (1) The tetravalent vanadium in the vanadium-containing leaching solution is oxidized to pentavalent vanadium using an oxidizing agent, and then the pH value is adjusted to 4-6 to obtain the feed solution; the vanadium concentration of the feed solution is >5g / L; (2) The feed liquid and nickel powder are mixed and a first reduction reaction is carried out under hydrogen conditions to obtain a primary slurry; (3) The primary slurry and nickel sulfate are mixed and a second reduction reaction is carried out under hydrogen conditions to obtain vanadium trioxide slurry; (4) The vanadium trioxide slurry is subjected to wet magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry; the magnetic tailings slurry is subjected to solid-liquid separation and drying in sequence to obtain vanadium trioxide.

2. The method according to claim 1, characterized in that, The vanadium-containing leaching solution is one or more of the following: vanadium shale leaching solution, vanadium-containing steel slag leaching solution, waste vanadium catalyst leaching solution, vanadium-titanium magnetite leaching solution, and clay vanadium ore leaching solution. The pH value of the vanadium-containing leachate is -0.5 to 3; the vanadium concentration of the vanadium-containing leachate is ≥6.0 g / L, the phosphorus concentration is ≤1.0 g / L, the iron concentration is ≤1.8 g / L, and the silicon concentration is ≤1.0 g / L.

3. The method according to claim 1, characterized in that, The oxidant is one or more of sodium chlorate, potassium chlorate, perchloric acid, chloric acid, hypochlorous acid, hydrogen peroxide, sodium perchlorate, potassium perchlorate, sodium hypochlorite, and potassium hypochlorite.

4. The method according to claim 1, characterized in that, The first reduction reaction is carried out in an autoclave; the autoclave is filled with 40% to 60% of its capacity; the amount of nickel powder used is 1 to 3 g / L; the temperature of the first reduction reaction is 250 to 300°C, the reaction time is 0.5 to 2 h, the hydrogen partial pressure is 3 to 6 MPa, and the first reduction reaction is carried out under stirring conditions, with the stirring speed being 300 to 600 r / min.

5. The method according to claim 1 or 4, characterized in that, The nickel powder contains ≥99.5wt% nickel and has a particle size of less than 0.037mm.

6. The method according to claim 1, characterized in that, The second reduction reaction is carried out in an autoclave with a filling rate of 40% to 60%; the amount of nickel sulfate used is 15 to 25 g / L; the temperature of the second reduction reaction is 250 to 300 °C, the time is 1.5 to 3 h, the hydrogen partial pressure is 3 to 6 MPa, and the first reduction reaction is carried out under stirring conditions with a stirring speed of 300 to 600 r / min.

7. The method according to claim 1 or 6, characterized in that, The nickel sulfate is one or both of anhydrous nickel sulfate and nickel sulfate hexahydrate; the purity of the nickel sulfate is ≥99wt%.

8. The method according to claim 1, characterized in that, The wet magnetic separation is a wet high-gradient magnetic separation; the magnetic field strength of the wet magnetic separation is 2 to 10 kOe, and the diameter of the magnetic medium wire is 1.5 to 3 mm.

9. The method according to claim 1, characterized in that, After obtaining the magnetic concentrate slurry, the process also includes solid-liquid separation of the magnetic concentrate slurry, drying the resulting solid, and returning it to step (2).

10. The method according to claim 1, characterized in that, The alkaline solution obtained after solid-liquid separation of the magnetic tailings slurry is concentrated and returned to step (1) for recycling.