Method for promoting alkali leaching vanadium extraction through mechanical activation of iron trioxide-containing tailings

Abstract

The invention relates to a method for promoting alkali leaching and vanadium extraction by using mechanical activation of iron trioxide-containing tailings, which comprises the following steps: (1) mixing iron trioxide-containing tailings and vanadium slag, and carrying out ball milling for mechanical activation to obtain activated slurry; and (2) alkali and the activated slurry obtained in the step (1) are mixed, oxygen-containing gas is introduced for an alkaline leaching reaction, and vanadium-containing leachate is obtained. According to the method, mechanical activation of the tailings is utilized, the structure of a vanadium-containing ore phase in the vanadium slag is destroyed through the method of combining physical and chemical means, oxidation dissolution of vanadium is promoted, then efficient oxidation leaching of vanadium in the vanadium slag under the low-temperature and low-alkali conditions is achieved, the conditions are mild, the vanadium extraction rate is high, and industrial large-scale production is easy to achieve.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium chemical metallurgy, and in particular to a method for promoting alkali leaching of vanadium by mechanically activating tailings containing ferric oxide. Background Art

[0002] Vanadium slag is a vanadium-rich material produced by blowing vanadium-containing hot metal in the presence of oxygen-containing gas. As a direct raw material for vanadium extraction, vanadium slag accounts for about 70% of global vanadium production. The most common method for extracting vanadium from vanadium slag is the sodium roasting-water leaching method. This process combines vanadium slag with sodium salt at high temperature (750-850℃) to produce sodium vanadate. Although this method is widely used, it faces several significant disadvantages, including low vanadium extraction efficiency, large amounts of wastewater, and the release of waste gases such as hydrogen chloride (HCl), chlorine (Cl2), and sulfur dioxide (SO2). In response to these environmental issues, a cleaner calcium roasting-acid leaching method has been developed. This method uses calcium oxide or calcium salt as a roasting additive to convert vanadium spinel in vanadium slag into calcium vanadate at high temperature, thereby reducing the emission of harmful gases and the generation of wastewater. However, this method still faces challenges, including low vanadium extraction efficiency and the generation of large amounts of solid waste. These results highlight the limitations of current high-temperature roasting technology in achieving sustainable vanadium extraction, and new methods are urgently needed to address these environmental and efficiency challenges.

[0003] In order to improve resource utilization and reduce reaction energy consumption, vanadium slag wet vanadium extraction has gradually developed into a new clean and energy-saving method. CN102127655A proposes a method for decomposing vanadium slag with NaOH solution at normal pressure, with a reaction temperature of 180-260°C. Compared with the roasting process, the temperature and energy consumption of the vanadium extraction process are significantly reduced, and the vanadium extraction efficiency is significantly increased. However, due to the alkali concentration of up to 80%, the energy consumption of circulating alkali solution evaporation is very large. CN101812588A proposes a method for decomposing vanadium slag with potassium hydroxide solution at normal pressure, with a reaction temperature of 180-260°C, and a greatly reduced temperature. The disadvantage is that the potassium hydroxide medium cost is relatively high, and the generated potassium vanadate is not an industrial product and needs further separation and purification. CN111575495B proposes a method for strengthening the oxidation and decomposition of vanadium slag in NaOH solution with microbubbles, with a NaOH solution concentration of 30-40wt% and a temperature of 100-140°C. The NaOH solution concentration and reaction temperature are greatly reduced, but the disadvantage is that the aeration device is easily blocked and frequently replaced, which is not conducive to industrial continuous production. CN 117265297 A proposes a method for promoting alkali leaching of vanadium by co-grinding peroxide and vanadium slag, and further reducing the concentration of NaOH solution and the reaction temperature. The disadvantages are that the cost of peroxide is high and there are safety hazards in the ball milling process.

[0004] Therefore, how to achieve efficient and low-cost vanadium extraction under mild conditions has become a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide. The method can be carried out under normal pressure, with mild reaction conditions, high vanadium leaching rate in vanadium slag, good operating environment, and no dust or waste gas generation.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide, the method comprising the following steps:

[0008] (1) mixing tailings containing iron oxide and vanadium slag and ball milling them for mechanical activation to obtain an activated slurry;

[0009] (2) mixing an alkali and the activated slurry described in step (1), and introducing an oxygen-containing gas to carry out an alkali leaching reaction to obtain a vanadium-containing leaching solution.

[0010] The present invention promotes alkaline leaching of vanadium by adding tailings containing ferric oxide during the ball milling mechanical activation process. The main component of the tailings is Fe2O3, which is considered to be a very effective catalyst in the advanced oxidation process and can produce a large number of strong oxidizing active oxygen species through a variety of substrates and treatment methods (including hydrogen peroxide, persulfate, visible light / ultraviolet light, electricity and ultrasound). When the tailings are added during the ball milling process, under the action of mechanical force, the Fe2O3 in the tailings can stimulate the generation of active oxygen, promote the pre-oxidation of vanadium, and convert the trivalent vanadium in the vanadium spinel into tetravalent vanadium and / or pentavalent vanadium, so that its early partial dissolution promotes the disintegration of vanadium slag and enhances the leaching of vanadium in the vanadium slag. At the same time, the refinement of vanadium slag particles and the exposure of vanadium-containing phases under mechanical activation can improve the utilization rate of active oxygen and strengthen the oxidation reaction. It is worth noting that the tailings composition is similar to the tailings after alkaline oxidation leaching of vanadium slag, which means that the tailings as an additive will not introduce additional impurities into the system.

[0011] Preferably, after the alkaline leaching reaction is completed, solid-liquid separation is performed to obtain a vanadium-containing leaching solution and leaching residue.

[0012] The present invention has no limitation on the solid-liquid separation, and any method known to those skilled in the art for solid-liquid separation may be used, and may also be adjusted according to actual conditions, such as filtration, sedimentation or centrifugation.

[0013] Preferably, the vanadium slag in step (1) is the vanadium slag produced by converter blowing during the smelting process of vanadium-titanium magnetite.

[0014] Preferably, the content of vanadium in the vanadium slag calculated as vanadium pentoxide is 8-20wt%, for example, it can be 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%, etc.

[0015] Preferably, the vanadium slag also contains any one of Cr, Fe, Ti, Si, Mg, Ca, Mn or Al, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of Cr and Fe, a combination of Ti and Fe, a combination of Cr and Ti, a combination of Si and Fe, a combination of Cr and Mg, or a combination of Ca and Al, etc.

[0016] The vanadium slag of the present invention contains vanadium iron spinel, which has the characteristics of complex mineral phase structure and difficult conversion, resulting in difficulty in extracting vanadium.

[0017] Preferably, the ferric oxide-containing tailings in step (1) include any one of vanadium extraction tailings, red mud or electrolytic aluminum anode mud, or a combination of at least two thereof, preferably vanadium extraction tailings.

[0018] Preferably, the vanadium extraction tailings include tailings produced after sodium roasting of vanadium slag and water leaching for vanadium extraction.

[0019] Preferably, the red mud comprises residues produced during the Bayer process of extracting alumina from bauxite.

[0020] Preferably, the aluminum electrolysis anode mud includes anode mud gradually formed during the aluminum electrolysis process due to the loss of anode materials, accumulation of impurities and the influence of electrolytic cell operating conditions.

[0021] Preferably, the content of ferric oxide in the ferric oxide-containing tailings in step (1) is 30-50wt%, for example, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%.

[0022] Preferably, the ferric oxide tailings also contain any one of Ti, Si, Mg, Ca, Mn or Al, or a combination of at least two of them.

[0023] The present invention preferably uses vanadium extraction tailings, which can achieve secondary recovery of vanadium in the vanadium extraction tailings.

[0024] Preferably, the mass ratio of the ferric oxide-containing tailings to the vanadium slag is 0.05-0.4:1, for example, it can be 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1 or 0.4:1, etc., preferably 0.1-0.3:1.

[0025] The present invention preferably controls the mass ratio of tailings to vanadium slag within the above range. When the amount is too small, there is a defect of low vanadium extraction rate, and when the amount is too large, there is a defect of low production efficiency.

[0026] Preferably, a solvent is also added during the ball milling in step (1).

[0027] Preferably, the solvent comprises water.

[0028] Preferably, the liquid-to-solid ratio of the solvent to the vanadium slag is 0.1-5 mL / g, for example, 0.1 mL / g, 1 mL / g, 1.2 mL / g, 1.5 mL / g, 2 mL / g, 2.5 mL / g, 3 mL / g, 3.2 mL / g, 3.5 mL / g, 4.0 mL / g, 4.5 mL / g or 5 mL / g, etc., preferably 0.5-2 mL / g.

[0029] Preferably, the ball milling time in step (1) is 1 to 120 min, for example, it can be 1 min, 10 min, 20 min, 30 min, 50 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, preferably 10 to 50 min.

[0030] The present invention can improve the vanadium extraction rate by further controlling the mechanical activation time and the vanadium slag particle size within a certain range. When the mechanical activation time is too short, the vanadium slag particles have not yet been refined, and the surface lattice defects have not yet been formed, resulting in reduced vanadium extraction efficiency. When the mechanical activation time is too long, energy consumption will increase, resulting in reduced economic efficiency of vanadium extraction.

[0031] Preferably, the ball-to-material ratio of the ball mill is 5:1 to 40:1, for example, it can be 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1 or 40:1, and is preferably 15:1 to 25:1.

[0032] Preferably, the rotation speed of the ball mill is 100-500 rpm, for example, it can be 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, etc., preferably 200-400 rpm.

[0033] Preferably, the particle size of the vanadium slag in the activation slurry in step (1) is 13 to 48 μm, for example, it can be 13 μm, 18 μm, 23 μm, 28 μm, 33 μm, 38 μm, 43 μm or 48 μm, etc., preferably 18 to 38 μm.

[0034] Preferably, the oxygen-containing gas in step (2) comprises any one of air, oxygen-enriched air or oxygen, or a combination of at least two of them, wherein a typical but non-limiting combination is a combination of air and oxygen, a combination of oxygen-enriched air and oxygen, or a combination of oxygen-enriched air and air, etc.

[0035] Preferably, the inlet flow rate of the oxygen-containing gas is 0.1 to 1.5 L / min, for example, it can be 0.1 L / min, 0.2 L / min, 0.3 L / min, 0.5 L / min, 0.8 L / min, 1.0 L / min, 1.2 L / min or 1.5 L / min, etc.

[0036] Preferably, the oxygen-containing gas is introduced continuously.

[0037] Preferably, the temperature of the alkali leaching reaction in step (2) is 50-130°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C, etc., preferably 70-110°C.

[0038] Preferably, the alkali leaching reaction time is 1 to 7 hours, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h or 7 h, etc., preferably 3 to 5 hours.

[0039] Preferably, the concentration of the mixed alkali and the alkali after activating the slurry in step (1) in the mixed system is 1 to 40 wt%, for example, it can be 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt% or 40 wt%, etc., preferably 5 to 20 wt%.

[0040] Preferably, the base comprises sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide.

[0041] The present invention can reduce the temperature and alkali concentration of the alkali leaching reaction to the above range by adding tailings for mechanical activation. Too low temperature and too low alkali concentration lead to reduced system activity and reduced vanadium extraction efficiency. Too high temperature and alkali concentration increase energy consumption and alkali dosage, reduce economic efficiency, and increase impurity concentration in the vanadium-containing leaching solution. The temperature and alkali concentration range of the present invention significantly reduce energy consumption compared to the prior art, and is a green, economical and efficient vanadium extraction method, which is of great significance for the efficient and clean extraction of vanadium slag.

[0042] Preferably, the liquid-to-solid ratio of the alkali leaching reaction is 2 to 10 mL / g, for example, it can be 2 mL / g, 3 mL / g, 4 mL / g, 5 mL / g, 6 mL / g, 7 mL / g, 8 mL / g, 9 mL / g or 10 mL / g, etc., preferably 3 to 6 mL / g.

[0043] The alkali leaching method of vanadium in the present invention can be carried out under normal pressure, and the reaction conditions are mild. Normal pressure refers to a pressure environment without pressurization or decompression, which is the same as the atmospheric pressure condition. Depending on the geographical location, altitude and temperature, its absolute pressure range is generally within the range of 98 to 102 kPa.

[0044] As a preferred technical solution of the present invention, the present invention provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide, the method comprising the following steps:

[0045] (1) mixing tailings containing iron oxide and vanadium slag in a mass ratio of 0.05 to 0.4:1, adding water, wherein the liquid-solid ratio of water to vanadium slag is 0.1 to 5 mL / g, and mechanically activating the mixture by ball milling at a ball-to-material ratio of 5:1 to 40:1 and a rotation speed of 100 to 500 rpm for 1 to 120 min to obtain an activated slurry containing vanadium slag with a particle size of 13 to 48 μm;

[0046] (2) mixing an alkali and the activated slurry to an alkali concentration of 1 to 40 wt %, wherein the alkali comprises sodium hydroxide and / or potassium hydroxide, and continuously introducing an oxygen-containing gas at a flow rate of 0.1 to 1.5 L / min to carry out an alkali leaching reaction at 50 to 130° C. and a liquid-to-solid ratio of 2 to 10 mL / g for 1 to 7 hours to obtain a vanadium-containing leaching solution.

[0047] Compared with the prior art, the present invention has at least the following beneficial effects:

[0048] (1) The present invention provides a method for promoting vanadium extraction by alkaline leaching by mechanical activation of tailings containing ferric oxide. Under the action of mechanical activation, the vanadium slag undergoes lattice distortion and dislocation, and the arrangement of particles in the lattice lattice partially loses periodicity, forming lattice defects, resulting in increased lattice internal energy, changes in surface properties, and enhanced reaction activity, thereby significantly improving the leaching efficiency of the vanadium slag. In addition, the tailings catalytically produce active oxygen, which can promote the pre-oxidation of vanadium and strengthen the leaching of vanadium. The vanadium extraction rate is ≥80%, which can reach more than 93% under preferred conditions, and can reach more than 98% at the highest. The impurity element content of the vanadium-containing leaching solution is less than 6ppm, and the lowest can reach 2.89ppm, indicating that the method provided by the present invention can achieve efficient extraction of vanadium.

[0049] (2) The method provided by the present invention for promoting vanadium extraction by alkaline leaching by mechanical activation of tailings containing ferric oxide does not require preliminary roasting, thus avoiding the generation of waste gas during the roasting process at the source, and no dust or waste gas harmful to the environment is generated during the reaction process.

[0050] (3) The method provided by the present invention utilizes mechanical activation of tailings containing ferric oxide to promote alkaline leaching of vanadium. It does not require the addition of expensive catalysts such as peroxides, thereby achieving the reuse of solid waste (tailings) as a catalyst, reducing production costs and minimizing environmental pollution. It is a potential alternative for the green treatment of vanadium slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a flow chart of the method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only 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.

[0053] Example 1

[0054] This embodiment provides a method for promoting vanadium extraction by alkaline leaching by mechanical activation of tailings containing ferric oxide, such as Figure 1 As shown, the method comprises the following steps:

[0055] (1) mixing vanadium extraction tailings (the vanadium extraction tailings are tailings produced after sodium roasting of vanadium slag and water leaching of vanadium, and the Fe2O3 content in the vanadium extraction tailings is 39.8wt%) and vanadium slag (the V2O5 content in the vanadium slag is 13.8wt%) in a mass ratio of 0.3:1, adding water, the liquid-solid ratio of water to vanadium slag is 1mL / g, and mechanical activation is performed by ball milling for 20min, the ball-to-material ratio is 20:1, and the rotation speed is 400rpm, to obtain an activated slurry containing vanadium slag with an average particle size of 28μm;

[0056] (2) mixing sodium hydroxide and the activated slurry until the concentration of the sodium hydroxide solution is 15 wt % and adjusting the liquid-to-solid ratio to 5 mL / g, then continuously introducing oxygen at a flow rate of 1 L / min to carry out an alkaline leaching reaction at 100° C. for 5 h, filtering after the alkaline leaching reaction to obtain a vanadium-containing leaching solution and leaching residue.

[0057] Example 2

[0058] This embodiment provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide, the method comprising the following steps:

[0059] (1) mixing vanadium extraction tailings (the vanadium extraction tailings are tailings produced after sodium roasting of vanadium slag and water leaching of vanadium, and the Fe2O3 content in the vanadium extraction tailings is 32.42wt%) and vanadium slag (the V2O5 content in the vanadium slag is 18.2wt%) in a mass ratio of 0.2:1, adding water, the liquid-solid ratio of water to vanadium slag is 1mL / g, and mechanical activation is performed by ball milling for 40 minutes, the ball-to-material ratio is 15:1, and the rotation speed is 300rpm, to obtain an activated slurry containing vanadium slag with an average particle size of 18μm;

[0060] (2) mixing sodium hydroxide and the activated slurry until the concentration of the sodium hydroxide solution is 20 wt %, and adjusting the liquid-to-solid ratio to 3 mL / g, and then continuously introducing oxygen at a flow rate of 1.5 L / min to carry out an alkaline leaching reaction at 70° C. for 5 h, and filtering after the alkaline leaching reaction to obtain a vanadium-containing leaching solution and a leaching residue.

[0061] Example 3

[0062] This embodiment provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide, the method comprising the following steps:

[0063] (1) mixing vanadium extraction tailings (the vanadium extraction tailings are tailings produced after sodium roasting of vanadium slag and water leaching of vanadium, and the Fe2O3 content in the vanadium extraction tailings is 41.65wt%) and vanadium slag (the V2O5 content in the vanadium slag is 16.9wt%) in a mass ratio of 0.25:1, adding water, the liquid-solid ratio of water to vanadium slag is 1.5mL / g, and mechanically activating by ball milling for 30min, the ball-to-material ratio is 25:1, and the rotation speed is 300rpm, to obtain an activated slurry containing vanadium slag with an average particle size of 23μm;

[0064] (2) mixing sodium hydroxide and the activated slurry until the concentration of the sodium hydroxide solution is 18 wt % and adjusting the liquid-to-solid ratio to 3 mL / g, then continuously introducing oxygen at a flow rate of 1 L / min to carry out an alkaline leaching reaction at 95° C. for 4 h, filtering after the alkaline leaching reaction to obtain a vanadium-containing leaching solution and leaching residue.

[0065] Example 4

[0066] This embodiment provides a method for promoting alkali leaching of vanadium by mechanical activation of tailings containing ferric oxide, the method comprising the following steps:

[0067] (1) mixing vanadium extraction tailings (the vanadium extraction tailings are tailings produced after sodium roasting of vanadium slag and water leaching of vanadium, and the Fe2O3 content in the vanadium extraction tailings is 47.52wt%) and vanadium slag (the V2O5 content in the vanadium slag is 17.4wt%) in a mass ratio of 0.2:1, adding water, the liquid-solid ratio of water to vanadium slag is 2mL / g, and mechanical activation is performed by ball milling for 30 minutes, the ball-to-material ratio is 25:1, and the rotation speed is 500rpm to obtain an activated slurry containing vanadium slag with an average particle size of 18μm;

[0068] (2) mixing sodium hydroxide and the activated slurry until the concentration of the sodium hydroxide solution is 20 wt% and adjusting the liquid-to-solid ratio to 6 mL / g, then continuously introducing oxygen at a flow rate of 1 L / min to carry out an alkaline leaching reaction at 110° C. for 3 h, filtering after the alkaline leaching reaction to obtain a vanadium-containing leaching solution and leaching residue.

[0069] Example 5

[0070] This embodiment provides a method for promoting vanadium extraction by alkaline leaching by mechanical activation of tailings containing ferric oxide. The method is the same as that of embodiment 1 except that the vanadium extraction tailings in step (1) are replaced by red mud (the red mud is the residue produced in the process of extracting aluminum oxide from bauxite by the Bayer process, and the Fe2O3 content in the red mud is 41.5wt%).

[0071] Example 6

[0072] The present embodiment provides a method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide. The method is the same as that of Example 1, except that the vanadium extraction tailings in step (1) are replaced by over-electrolytic aluminum anode mud (the electrolytic aluminum anode mud includes anode mud gradually formed during the aluminum electrolysis process due to the loss of anode materials, accumulation of impurities and the influence of electrolytic cell operating conditions, and the Fe2O3 content in the electrolytic aluminum anode mud is 38.1wt%).

[0073] Example 7

[0074] This embodiment provides a method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide. The method is the same as that of Embodiment 1 except that the mass ratio of the vanadium extraction tailings to the vanadium slag is 1:1.

[0075] Example 8

[0076] This embodiment provides a method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide. The method is the same as that of Embodiment 1 except that the mass ratio of vanadium extraction tailings to vanadium slag is 0.05:1.

[0077] Example 9

[0078] This embodiment provides a method for promoting alkaline leaching of vanadium by mechanical activation of tailings containing ferric oxide. The method is the same as Example 1 except that the mechanical activation time is 5 minutes and an activated slurry containing vanadium slag with an average particle size of 45 μm is obtained.

[0079] Example 10

[0080] This embodiment provides a method for promoting alkaline leaching of vanadium by mechanical activation of tailings containing ferric oxide. The method is the same as that of Embodiment 1 except that in step (2), sodium hydroxide and the activation slurry are mixed until the concentration of the sodium hydroxide solution is 3wt%.

[0081] Embodiment 11

[0082] This embodiment provides a method for promoting alkaline leaching of vanadium by mechanical activation of tailings containing ferric oxide. The method is the same as that of Embodiment 1 except that in step (2), sodium hydroxide and the activation slurry are mixed until the concentration of the sodium hydroxide solution is 40wt%.

[0083] Example 12

[0084] This embodiment provides a method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide. The method is the same as that of embodiment 1 except that the temperature of the alkaline leaching reaction in step (2) is 50°C.

[0085] Example 13

[0086] This embodiment provides a method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide. The method is the same as that of embodiment 1 except that the temperature of the alkaline leaching reaction in step (2) is 130°C.

[0087] Comparative Example 1

[0088] This comparative example provides a method for extracting vanadium by alkaline leaching, which is the same as Example 1 except that ball milling is not performed.

[0089] Comparative Example 2

[0090] This comparative example provides a method for extracting vanadium by alkaline leaching, which is the same as Example 1 except that no vanadium extraction tailings are added.

[0091] Comparative Example 3

[0092] This comparative example provides a method for extracting vanadium by alkali leaching, which is the same as Example 1 except that the vanadium extraction tailings are added to step (2) instead of step (1).

[0093] Comparative Example 4

[0094] This comparative example provides a method for extracting vanadium by alkaline leaching, which is the same as Example 1 except that no vanadium extraction tailings are added and no ball milling mechanical activation is performed.

[0095] Test method: The mass of the iron oxide tailings and the vanadium content in the above embodiments and comparative examples were detected by ICP method, and the vanadium extraction rate was calculated according to the mass of the raw materials and the content of each element therein. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] The test results show that:

[0100] (1) It can be seen from Examples 1 to 6 that the method for extracting vanadium by alkaline leaching by mechanical and chemical synergistic activation provided by the present invention can achieve good vanadium extraction, and the vanadium extraction rate can reach more than 93%, and the highest can reach more than 98%. The impurity element content of the vanadium-containing leachate is less than 6 ppm, and the lowest can reach 2.89 ppm, and the process economy is high.

[0101] (2) It can be seen from the combination of Example 1 and Examples 5-6 that the leaching rate of mechanical activation using vanadium extraction tailings in Example 1 is not much different from that using red mud and electrolytic aluminum anode mud in Examples 5 and 6, respectively. Any one or a combination of at least two of vanadium extraction tailings, red mud or electrolytic aluminum anode mud can be used as an additive, but since vanadium extraction tailings also contain a small amount of vanadium, using vanadium extraction tailings as an additive can achieve secondary recovery of vanadium in vanadium extraction tailings.

[0102] (3) It can be seen from Example 1 and Examples 7 to 8 that the mass ratio of vanadium extraction tailings to vanadium slag in Example 7 is 4:1, and the leaching rate of vanadium remains unchanged. However, excessive use of vanadium extraction tailings leads to a reduction in the amount of vanadium slag processed and a decrease in production efficiency. In Example 8, the mass ratio of vanadium extraction tailings to vanadium slag is 0.5:1, and the leaching rate of vanadium is reduced from 96% to 87%. Since the amount of vanadium extraction tailings used is too low, it is not enough to achieve the pre-oxidation of low-valent vanadium in the vanadium slag in the ball milling stage, which limits the leaching and dissolution behavior of the vanadium slag in the subsequent leaching process. This shows that the present invention significantly improves the leaching rate and effectively saves costs by controlling the addition amount of vanadium extraction tailings within a specific range.

[0103] (4) It can be seen from Example 1 and Example 9 that the mechanical activation time in Example 1 is 20 minutes, and the activated slurry with a vanadium slag particle size of 28 μm is obtained. The mechanical activation time in Example 9 is 5 minutes, and the activated slurry with an average vanadium slag particle size of 45 μm is obtained. The vanadium extraction rate in Example 1 is 96%, and the vanadium extraction rate in Example 9 is 84%. The leaching rate is significantly reduced. This is because the mechanical activation time is too short, the vanadium slag particles have not been refined, and the surface lattice defects have not been formed, so the vanadium leaching rate is greatly reduced. This shows that the present invention can improve the vanadium extraction rate by further controlling the mechanical activation time and the vanadium slag particle size within a certain range.

[0104] (5) It can be seen from Example 1 and Examples 10 to 13 that the lowering of the alkali concentration and the temperature of the alkali leaching reaction in Example 10 and Example 12 resulted in a decrease in the activity of the system, and the leaching rate of vanadium was reduced to 81% and 80%, respectively. In Example 11 and Example 13, the leaching rate of vanadium was not further improved by increasing the alkali concentration and the temperature of the alkali leaching reaction, while the content of impurity elements in the vanadium leaching solution increased to 6.63 ppm and 7.12 ppm, respectively. This shows that the present invention can improve the vanadium extraction rate and reduce the impurity content in the vanadium-containing leaching solution by further controlling the reaction temperature and the alkali leaching concentration within a certain range.

[0105] (6) It can be seen from Example 1 and Comparative Example 1 that Example 1 uses mechanical activation to strengthen the extraction of vanadium. Compared with Comparative Example 1 without mechanical activation, the extraction rate of vanadium in Example 1 is 97%, and the extraction rate of vanadium in Comparative Example 1 is 71%. This shows that under the action of mechanical activation, the mineral structure of the vanadium slag is destroyed, the reaction activity of the vanadium slag is improved, and the extraction of vanadium is promoted.

[0106] (7) It can be seen from Example 1 and Comparative Example 2 that Example 1 uses mechanical activation of tailings to enhance the extraction of vanadium. Compared with Comparative Example 2 in which no vanadium-extracting tailings are added, the vanadium extraction rate in Example 1 is 97%, and the vanadium extraction rate in Comparative Example 2 is 77%. This shows that the addition of vanadium-extracting tailings can promote the generation of active oxygen species during the mechanical activation process, achieve pre-oxidation of vanadium slag, and improve the vanadium extraction rate.

[0107] (8) It can be seen from Example 1 and Comparative Example 3 that in Comparative Example 3, the vanadium extraction tailings are added to step (2) instead of to step (1), and the vanadium leaching rate is reduced from 97% to 85%. This shows that the main function of the vanadium extraction tailings is to promote the generation of active oxygen species in the system during the mechanical activation stage, thereby achieving pre-oxidation of the vanadium slag and improving the vanadium leaching rate. The present invention selects to first use mechanical activation of the tailings and then perform alkaline leaching reaction to better improve the extraction rate.

[0108] (9) It can be seen from Example 1 and Comparative Example 4 that in Comparative Example 4, when neither ball mill mechanical activation nor vanadium extraction tailings was added, the leaching rate of vanadium decreased significantly from 97% to 52%. This shows that the present invention significantly promotes the leaching of vanadium from vanadium slag through the synergistic effect of ball mill mechanical activation and the introduction of ferric oxide-containing tailings.

[0109] In summary, the method for extracting vanadium from vanadium slag by mechanical activation of tailings provided by the present invention causes lattice distortion and dislocation of vanadium slag, and at the same time, the arrangement of particles in the lattice lattice partially loses periodicity, forming lattice defects, resulting in increased lattice internal energy, changes in surface properties, and enhanced reaction activity; at the same time, the tailings can stimulate the generation of active oxygen, promote the pre-oxidation of vanadium, and convert trivalent vanadium in vanadium spinel into tetravalent vanadium and / or pentavalent vanadium, so that its early part is dissolved to promote the disintegration of vanadium slag and enhance the leaching of vanadium in vanadium slag. Under optimal conditions, the vanadium extraction rate is above 96%, and the economic benefits are relatively high.

[0110] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for promoting vanadium extraction by alkaline leaching using mechanical activation of tailings containing ferric oxide, characterized in that: The method comprises the following steps: (1) mixing tailings containing iron oxide and vanadium slag and ball milling them for mechanical activation to obtain an activated slurry; (2) mixing an alkali and the activated slurry described in step (1), and introducing an oxygen-containing gas to carry out an alkali leaching reaction to obtain a vanadium-containing leaching solution.

2. The method according to claim 1, characterized in that The vanadium slag in step (1) is the vanadium slag produced by converter blowing during the smelting process of vanadium-titanium magnetite.

3. The method according to claim 1 or 2, characterized in that: The ferric oxide-containing tailings in step (1) include any one of vanadium extraction tailings, red mud or electrolytic aluminum anode mud, or a combination of at least two thereof, preferably vanadium extraction tailings; Preferably, the content of ferric oxide in the ferric oxide-containing tailings is 30-50wt%; Preferably, the mass ratio of the ferric oxide-containing tailings to the vanadium slag is 0.05-0.4:1, preferably 0.1-0.3:

1.

4. The method according to any one of claims 1 to 3, characterized in that: In step (1), a solvent is also added during the ball milling; Preferably, the solvent comprises water; Preferably, the liquid-to-solid ratio of the solvent to the vanadium slag is 0.1 to 5 mL / g, preferably 0.5 to 2 mL / g.

5. The method according to any one of claims 1 to 4, characterized in that: The ball milling time in step (1) is 1 to 120 min, preferably 10 to 50 min; Preferably, the ball-to-material ratio of the ball mill is 5:1 to 40:1, preferably 15:1 to 25:1; Preferably, the rotation speed of the ball mill is 100 to 500 rpm, preferably 200 to 400 rpm.

6. The method according to any one of claims 1 to 5, characterized in that: The particle size of the vanadium slag in the activation slurry in step (1) is 13 to 48 μm, preferably 18 to 38 μm.

7. The method according to any one of claims 1 to 6, characterized in that: The oxygen-containing gas in step (2) includes any one of air, oxygen-enriched air or oxygen, or a combination of at least two thereof; Preferably, the oxygen-containing gas has an inlet flow rate of 0.1 to 1.5 L / min.

8. The method according to any one of claims 1 to 7, characterized in that: The temperature of the alkali leaching reaction in step (2) is 50 to 130° C., preferably 70 to 110° C.; Preferably, the alkali leaching reaction time is 1 to 7 hours, preferably 3 to 5 hours; Preferably, the concentration of the mixed alkali and the alkali after activating the slurry in step (1) in the mixed system is 1 to 40 wt%, preferably 5 to 20 wt%; Preferably, the base comprises sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide.

9. The method according to any one of claims 1 to 8, characterized in that: The liquid-to-solid ratio of the alkali leaching reaction is 2 to 10 mL / g, preferably 3 to 6 mL / g.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) mixing tailings containing iron oxide and vanadium slag in a mass ratio of 0.05 to 0.4:1, adding water, wherein the liquid-solid ratio of water to vanadium slag is 0.1 to 5 mL / g, and mechanically activating the mixture by ball milling at a ball-to-material ratio of 5:1 to 40:1 and a rotation speed of 100 to 500 rpm for 1 to 120 min to obtain an activated slurry containing vanadium slag with a particle size of 13 to 48 μm; (2) mixing an alkali and the activated slurry to an alkali concentration of 1 to 40 wt %, wherein the alkali comprises sodium hydroxide and / or potassium hydroxide, and continuously introducing an oxygen-containing gas at a flow rate of 0.1 to 1.5 L / min to carry out an alkali leaching reaction at 50 to 130° C. and a liquid-to-solid ratio of 2 to 10 mL / g for 1 to 7 hours to obtain a vanadium-containing leaching solution.

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