Method for extracting vanadium and chromium through self-catalysis of vanadium and chromium-containing sludge reinforced by micro-nano bubbles in aqueous alkali

Abstract

The invention relates to a method for extracting vanadium and chromium through self-catalysis of vanadium-containing and chromium-containing mud reinforced by micro-nano bubbles in an alkaline solution, which comprises the following steps: introducing micro-nano oxygen-containing bubbles into mixed slurry of the alkaline solution and the vanadium-containing and chromium-containing mud to carry out synchronous reaction which comprises a Fenton-like reaction and an alkaline leaching reaction which are synchronously carried out, and in the synchronous reaction process, an alkali solution and vanadium-containing and chromium-containing sludge are intermittently supplemented, and a vanadium-containing and chromium-containing leaching solution is obtained. According to the method, active oxygen generated by strengthening of the microbubbles and hydroxyl free radicals generated by Fenton-like reaction are used for jointly strengthening damage of phase structures containing vanadium and chromium in the sludge containing vanadium and chromium, and oxidation dissolution of vanadium and chromium is promoted. And efficient leaching of vanadium and chromium in the vanadium-containing chromium mud is achieved under the conditions of low alkali concentration and low temperature, and industrial large-scale production is easy to achieve.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium and chromium chemical metallurgy, and in particular to a method for extracting vanadium and chromium from vanadium-containing chromium mud by self-catalysis enhanced by micro-nano bubbles in an alkaline solution. Background Art

[0002] Vanadium slag is the main raw material for vanadium extraction. Since vanadium and chromium coexist, chromium is the main impurity that must be removed during the vanadium extraction process. However, due to the similar physical and chemical properties of vanadium and chromium, it is often difficult to separate them during the extraction process. Therefore, in the existing vanadium slag sodium roasting process for vanadium extraction, part of the chromium will be leached into the vanadium-containing liquid along with the vanadium. After the vanadium product ammonium salt precipitation and separation, a small amount of unprecipitated vanadium and chromium remain in the vanadium precipitation mother liquor, forming vanadium precipitation wastewater containing chromium and vanadium. For the treatment of vanadium precipitation wastewater, the industry mainly uses chemical reduction method to achieve the removal and separation of chromium, such as adding reducing agent sodium pyrosulfite to reduce chromium from hexavalent to trivalent, and vanadium from pentavalent to tetravalent or trivalent, and adjusting the solution pH to about 8 to precipitate vanadium and chromium as precipitates to obtain vanadium-containing chromium mud.

[0003] The contents of vanadium and chromium in vanadium-chromium mud can reach 1-30wt% and 5-30wt% respectively, which is much higher than the contents of vanadium and chromium in primary resources such as vanadium-titanium magnetite, and has great extraction value. At the same time, the storage of chromium resources in vanadium-chromium mud will not only cause waste of resources, but more importantly, the small amount of hexavalent chromium contained in it is a carcinogenic toxic substance that harms the ecological environment. Therefore, the recovery and utilization of vanadium and chromium in vanadium-chromium mud is of great significance to the safety of vanadium and chromium resources.

[0004] At present, the main methods for extracting vanadium and chromium from vanadium-chromium mud include roasting-leaching method, pressure oxidation-leaching method and oxidant oxidation-leaching method.

[0005] CN104178637A discloses a method for extracting vanadium and chromium from vanadium-containing chromium mud by two-step roasting. The first step is calcification roasting at a temperature of 800-950°C. The roasted product is acid-leached to obtain a vanadium-containing leachate and a solid phase. In the second step, the solid phase obtained by the first roasting is sodium-roasted at 800-900°C, and the roasted product is water-leached to obtain a chromium-containing leachate. In order to reduce the roasting temperature, CN104178638A discloses a method for extracting vanadium and chromium by roasting and leaching chromium salts. The roasting temperature of the method is 300-400°C, and the roasted product is water-leached to obtain a vanadium-containing leachate and a solid phase. The solid phase is then acid-leached or alkaline-leached to obtain a chromium-containing leachate, thereby realizing the step-by-step extraction of vanadium and chromium. In order to simplify the vanadium-chromium extraction steps, CN107619941A discloses a single-step vanadium-chromium co-extraction method, in which vanadium-chromium mud is mixed with soda ash and aluminum salt to form pellets, and then roasted at 840-870°C to obtain roasted clinker, and the clinker is soaked in water to obtain a vanadium-chromium mixed solution.

[0006] The above roasting-leaching method has the disadvantages of high roasting temperature and long process. In order to improve resource utilization, reduce reaction energy consumption and simplify the process, wet extraction of vanadium and chromium from vanadium-chromium mud has gradually developed.

[0007] CN110564979A discloses a method for extracting vanadium and chromium by pressurized alkali leaching, wherein the vanadium-containing chromium mud is mixed with alkali solution and then deaminated, and then reacted under the conditions of alkali concentration of 30-40wt%, reaction temperature of 150-180°C, and reaction oxygen pressure of 5.5-7.5MPa, and solid-liquid separation to obtain vanadium-containing chromium leaching solution and leaching residue, and the leaching solution is crystallized to obtain sodium vanadate and sodium chromate products. This method requires high reaction pressure and temperature, and has high requirements on equipment.

[0008] CN111575490A discloses a method for extracting vanadium and chromium from vanadium-chromium mud by aeration and pressurized oxidation alkali leaching. The method introduces calcium oxide as a stabilizer to enhance the performance of bubble formation and promote the extraction efficiency of vanadium and chromium. The method achieves efficient extraction of vanadium and chromium under the conditions of alkali concentration of 30-40wt%, reaction temperature of 155-180℃ and reaction oxygen pressure of 0.5-0.8MPa. The method has high requirements on reaction alkali concentration and temperature.

[0009] CN107201445A discloses a method for extracting vanadium and chromium by hydrogen peroxide oxidation and alkali leaching. The method first uses a 100g / L NaOH solution as a leaching agent to extract vanadium from vanadium-chromium mud at 70°C and nitrogen protective gas. After solid-liquid separation, the filtered residue is oxidized by adding hydrogen peroxide, and then the chromium extraction reaction is carried out under 100g / L NaOH solution, 70°C, and nitrogen protective gas. The method realizes the step-by-step extraction of vanadium and chromium, but requires the introduction of a nitrogen protective atmosphere, and the process is relatively long.

[0010] In summary, there are many problems in the existing recovery and treatment methods of vanadium-containing chromium mud, and it is urgent to develop a mild treatment method for vanadium-containing chromium mud with low equipment requirements, relatively low energy consumption and simple process flow. Summary of the invention

[0011] In order to solve the above technical problems, the present invention provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud in an alkaline solution by using micro-nano bubbles to enhance the autocatalytic extraction of vanadium and chromium from vanadium-containing chromium mud. The method can be carried out under normal pressure, with mild reaction conditions, high vanadium leaching rate in the vanadium-containing chromium mud, good operating environment, and no dust or waste gas generation.

[0012] To achieve this object, the present invention adopts the following technical solutions:

[0013] In a first aspect, the present invention provides a method for extracting vanadium and chromium from vanadium-containing chromium mud by autocatalysis enhanced by micro-nano bubbles in an alkaline solution, the method comprising:

[0014] Micro-nano oxygen-containing bubbles are introduced into a mixed slurry of an alkali solution and vanadium-chromium mud to carry out a synchronous reaction, wherein the synchronous reaction includes a Fenton-like reaction and an alkali leaching reaction, and the alkali solution and the vanadium-chromium mud are intermittently replenished during the synchronous reaction to obtain a vanadium-chromium leaching solution.

[0015] The present invention introduces micro-nano oxygen-containing bubbles. Compared with ordinary bubbles, the micro-nano oxygen-containing bubbles have a small radius and a large internal pressure, and produce a local cavitation effect during the explosion process of the reaction system, which not only produces a certain shear effect on the vanadium-containing chromium mud, but also is accompanied by the generation of strong oxidizing active oxygen substances, mainly hydrogen peroxide, during the explosion process.

[0016] The Fenton reaction is a chain reaction between divalent iron and hydrogen peroxide, which produces highly oxidizing hydroxyl radicals. In the present invention, the peroxyl radicals produced by trivalent chromium and micro-nano oxygen-containing bubbles can form a Fenton-like system, and trivalent chromium can catalyze the Fenton-like reaction to produce highly oxidizing hydroxyl radicals, thereby strengthening the oxidation leaching process. Therefore, by continuously introducing micro-nano oxygen-containing bubbles, the generation of peroxyl radicals is strengthened, and the trivalent chromium in the vanadium-containing chromium mud catalyzes the Fenton-like reaction to produce hydroxyl radicals to enhance the oxidation ability. At the same time, the vanadium-containing chromium mud is added at regular intervals to ensure a stable supply of Fenton-like reaction catalysts, and the stable supply of the concentrations of the two ensures the efficient oxidation leaching of vanadium and chromium in the vanadium-containing chromium mud.

[0017] Preferably, after the synchronous reaction is completed, a vanadium-chromium-containing leaching solution and a leaching residue are obtained by solid-liquid separation. The solid-liquid separation can be carried out by any method known to those skilled in the art for solid-liquid separation, such as filtration, sedimentation or centrifugation.

[0018] Preferably, the source of the vanadium-containing chromium mud includes the vanadium-containing chromium mud generated during the chromium removal process of wastewater after vanadium precipitation in the sodium roasting process of vanadium slag.

[0019] Preferably, the vanadium content of the vanadium-containing chromium mud is 1 to 30wt%, for example, it can be 1wt%, 2wt%, 3wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt% or 30wt%, etc.

[0020] Preferably, the valence state of vanadium in the vanadium-containing chromium mud includes trivalent and / or tetravalent.

[0021] Preferably, the vanadium in the vanadium-containing chromium mud exists in the form of vanadium hydroxide and / or vanadium oxide, preferably vanadium oxide.

[0022] Preferably, the chromium content of the vanadium-containing chromium mud is 5-30wt%, for example, it can be 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt% or 30wt%.

[0023] Preferably, the valence state of chromium in the vanadium-containing chromium mud includes trivalent.

[0024] Preferably, the chromium in the vanadium-containing chromium mud exists in the form of chromium hydroxide and chromium trioxide.

[0025] The present invention promotes the leaching of vanadium and chromium by oxidizing trivalent or tetravalent vanadium in the vanadium-containing chromium mud into pentavalent vanadium and oxidizing trivalent chromium into hexavalent chromium. Meanwhile, the trivalent chromium in the vanadium-containing chromium mud raw material can catalyze the conversion of hydrogen peroxide generated by oxygen-containing microbubbles into hydroxyl radicals. On the one hand, the oxidation of trivalent chromium is achieved. On the other hand, the generated hydroxyl radicals with stronger oxidizing ability can further oxidize the vanadium and chromium in the vanadium-containing chromium mud, and the leaching of vanadium and chromium is promoted by synergistic effect.

[0026] Preferably, the alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution, preferably a sodium hydroxide solution.

[0027] Preferably, the concentration of the alkaline solution is 2-40wt%, for example, it can be 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc., preferably 5-20wt%.

[0028] Preferably, the liquid-to-solid ratio of the alkaline solution to the vanadium-containing chromium mud is 3 to 15 mL / g, for example, 3 mL / g, 5 mL / g, 8 mL / g, 10 mL / g, 12 mL / g or 15 mL / g, etc., preferably 7 to 12 mL / g.

[0029] Preferably, the diameter of the micro-nano oxygen-containing bubbles is ≤100 μm, for example, 0-200 nm, 300-500 nm, 800 nm-1 μm or 50 μm-100 μm, etc., preferably the diameter is ≤5 μm.

[0030] The invention further controls the size of the introduced micro-nano oxygen-containing bubbles within a preferred range, thereby enhancing the process of the micro-nano oxygen-containing bubbles bursting to generate perhydroxyl radicals, promoting the self-catalytic Fenton-like reaction, and improving the extraction rate of vanadium and chromium.

[0031] Preferably, the gas of the micro-nano oxygen-containing bubbles is 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 oxygen and air, a combination of air and oxygen-enriched air, or a combination of oxygen and oxygen-enriched air, etc.

[0032] Preferably, the micro-nano oxygen-containing bubbles are introduced in a continuous manner.

[0033] Preferably, the continuous introduction uses an aeration device.

[0034] Preferably, the continuous flow rate is 0.1-1.5 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.

[0035] Preferably, the interval time of the intermittent supplementation is 30 to 90 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, etc., preferably 30 to 60 min.

[0036] Preferably, the single replenishment amount of the vanadium-chromium mud in the intermittent replenishment is 0.5 to 2 times the mass of the initial vanadium-chromium mud, for example, it can be 0.5 times, 0.6 times, 0.7 times, 0.8 times, 0.9 times, 1.0 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times or 2.0 times, etc., preferably 0.5 to 1 times.

[0037] The present invention further preferably intermittently replenishes the amount of vanadium-chromium mud so that the content of trivalent chromium in the slurry system maintains a relative dynamic balance, so as to continuously catalyze the Fenton-like reaction and promote the oxidation and leaching of vanadium and chromium. The flow rate of continuous gas introduction is preferably such that the amount of micro-nano oxygen-containing bubbles introduced is sufficient to generate a large amount of perhydroxyl radicals, and the oxygen therein can be fully utilized in the oxidation reaction, thereby improving the utilization rate of the oxidizing gas.

[0038] Preferably, the concentration of the alkaline solution in the intermittent supplementation is 2 to 40 wt%, for example, it can be 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc., preferably 5 to 20wt%.

[0039] Preferably, the liquid-to-solid ratio of the intermittently replenished alkali solution and the vanadium-containing chromium mud is 3-15 mL / g, for example, it can be 3 mL / g, 5 mL / g, 8 mL / g, 10 mL / g, 12 mL / g or 15 mL / g, etc., preferably 7-12 mL / g.

[0040] Preferably, the number of intermittent supplementation is 3 to 10 times, for example, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, etc., preferably 3-6 times.

[0041] Preferably, the temperature of the synchronous reaction is 40-100°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, etc., preferably 70-100°C.

[0042] The present invention further optimizes the temperature of the synchronous reaction so that the reaction temperature satisfies the requirements of the alkali leaching reaction and the Fenton-like reaction at the same time.

[0043] Preferably, the synchronous reaction time is 2 to 17 hours, for example, it can be 2 hours, 3 hours, 5 hours, 10 hours, 15 hours or 17 hours.

[0044] As a preferred technical solution of the present invention, the method comprises:

[0045] An aeration device is used to continuously introduce oxygen-containing gas with a flow rate of 0.1 to 1.5 L / min into a mixed slurry of an alkaline solution with a concentration of 2 to 40 wt% and vanadium-containing chromium mud to form micro-nano oxygen-containing bubbles with a diameter of ≤100 μm, and a synchronous reaction is carried out at 40 to 100° C. for 2 to 17 hours. The synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out synchronously. The liquid-to-solid ratio of the alkaline solution to the vanadium-containing chromium mud is 3 to 15 mL / g. During the synchronous reaction, the alkaline solution with a concentration of 2 to 40 wt% and the vanadium-containing chromium mud with a liquid-to-solid ratio of 3 to 15 mL / g are supplemented once every 30 to 90 minutes. The single supplement amount of the vanadium-containing chromium mud is 0.5 to 2 times the mass of the initial vanadium-containing chromium mud, and the number of intermittent supplements is 3 to 10 times to obtain a vanadium-containing chromium leaching solution.

[0046] Compared with the prior art, the present invention has at least the following beneficial effects:

[0047] (1) The method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud by micro-nano bubbles in an alkaline solution provided by the present invention can significantly increase the solubility of oxygen in the alkaline solution and the oxidizing capacity of the solution under the participation of nano-micro-nano oxygen-containing bubbles. At the same time, due to the high internal pressure of the micro-nano oxygen-containing bubbles, a local cavitation effect will be generated when the bubbles burst, which will not only produce a shear effect on the minerals, but also stimulate the generation of substances with strong oxidizing activity during the bursting process, mainly hydrogen peroxide. The trivalent chromium in the vanadium-containing chromium mud can react with hydrogen peroxide to produce a Fenton-like reaction, which can achieve the oxidation of chromium on the one hand and generate hydroxyl radicals with stronger oxidizing ability on the other hand, which can further enhance the oxidation of vanadium and chromium in the vanadium-containing chromium mud. The simultaneous alkali leaching reaction and the Fenton-like reaction greatly promote the oxidation leaching of vanadium and chromium. Under optimal conditions, the vanadium extraction rate reaches more than 92%, and the chromium extraction rate reaches more than 90%.

[0048] (2) The method for extracting vanadium and chromium from vanadium and chromium-containing mud by self-catalytic extraction of vanadium and chromium by micro-nano bubbles in an alkaline solution provided by the present invention does not generate saline wastewater, and the reaction alkaline solution is relatively stable, not easy to volatilize, and can be recycled. In addition, only oxygen is introduced into the reaction process without adding other reagents, which not only avoids the separation problem caused by the introduction of other substances, but also makes the whole process clean and pollution-free.

[0049] (3) The method provided by the present invention for the self-catalytic extraction of vanadium and chromium from vanadium and chromium-containing mud by micro-nano bubbles in an alkaline solution can be carried out at normal pressure and low temperature, without the need for non-standard equipment such as pressure vessels and special corrosion-resistant equipment, and is easy for industrial production.

[0050] (4) The method for extracting vanadium and chromium from vanadium and chromium-containing mud by micro-nano bubbles in an alkaline solution provided by the present invention does not require preliminary roasting, thus avoiding the generation of waste gas during the roasting process, and no dust and waste gas harmful to the environment are generated during the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a process flow chart of the method for extracting vanadium and chromium from vanadium and chromium-containing mud by micro-nano bubble enhanced autocatalysis in alkaline solution 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] The source of the vanadium-containing chromium mud used in this embodiment is the vanadium-containing chromium mud produced in the process of removing chromium from wastewater after vanadium precipitation in the sodium roasting process of vanadium slag, wherein the vanadium content is 20.56wt%, and the vanadium exists in the form of vanadium oxide, and the chromium content is 16.74wt%, and the chromium exists in the form of chromium trioxide.

[0055] This embodiment provides a method for extracting vanadium and chromium from vanadium and chromium-containing mud by autocatalytic enhancement of micro-nano bubbles in a sodium hydroxide solution. Figure 1 As shown, the method includes:

[0056] A 5wt% sodium hydroxide solution and a vanadium-containing chromium mud are mixed at a liquid-solid ratio of 10mL / g to obtain a mixed slurry, and oxygen with a flow rate of 1.5L / min is continuously introduced into the mixed slurry by an aeration device to form micro-nano oxygen-containing bubbles with a diameter of ≤5μm, and a synchronous reaction is carried out at 95°C for 7h. The synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out simultaneously. During the reaction, a 5wt% sodium hydroxide solution and a vanadium-containing chromium mud with a liquid-solid ratio of 10mL / g are supplemented once every 60min; the single supplement amount of the vanadium-containing chromium mud is 1 times the mass of the initial vanadium-containing chromium mud, and the number of intermittent supplements is 6 times. After the reaction is completed, the vanadium-containing chromium leaching solution is obtained by filtration.

[0057] Example 2

[0058] The source of the vanadium-containing chromium mud used in this embodiment is the vanadium-containing chromium mud produced in the process of removing chromium from wastewater after vanadium precipitation in the sodium roasting process of vanadium slag, wherein the vanadium content is 25.67%, and the vanadium exists in the form of vanadium oxide, and the chromium content is 15.24%, and the chromium exists in the form of chromium hydroxide.

[0059] This embodiment provides a method for extracting vanadium and chromium from vanadium and chromium-containing mud by autocatalytic enhancement of micro-nano bubbles in a sodium hydroxide solution. Figure 1 As shown, the method includes:

[0060] A 40wt% sodium hydroxide solution and a vanadium-chromium mud are mixed at a liquid-solid ratio of 3mL / g to obtain a mixed slurry, and oxygen is continuously introduced into the mixed slurry at a flow rate of 1.2L / min using an aeration device to form micro-nano oxygen-containing bubbles with a diameter of ≤100μm, and a synchronous reaction is carried out at 70°C for 4h, wherein the synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out simultaneously. During the reaction, a 40wt% sodium hydroxide solution and a vanadium-chromium mud with a liquid-solid ratio of 3mL / g are supplemented once every 60min; a single supplement amount of the intermittently supplemented vanadium-chromium mud is 0.8 times the mass of the initial vanadium-chromium mud, and the intermittent supplementation is performed 3 times. After the reaction is completed, filtration is performed to obtain a vanadium-chromium leaching solution.

[0061] Example 3

[0062] The source of the vanadium-containing chromium mud used in this embodiment is the vanadium-containing chromium mud produced in the process of removing chromium from wastewater after vanadium precipitation in the sodium roasting process of vanadium slag, wherein the vanadium content is 18.26%, and the vanadium exists in the form of vanadium hydroxide. The chromium content is 12.48%, and the chromium exists in the form of chromium trioxide.

[0063] This embodiment provides a method for extracting vanadium and chromium from vanadium and chromium-containing mud by autocatalytic enhancement of micro-nano bubbles in a sodium hydroxide solution. Figure 1 As shown, the method includes:

[0064] An 8wt% sodium hydroxide solution and a vanadium-chromium mud are mixed at a liquid-solid ratio of 15mL / g to obtain a mixed slurry, and air with a flow rate of 1L / min is continuously introduced into the mixed slurry by an aeration device to form micro-nano oxygen-containing bubbles with a diameter of ≤10μm, and a synchronous reaction is carried out at 100°C for 3h, wherein the synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out simultaneously. During the reaction, an 8wt% sodium hydroxide solution and a vanadium-chromium mud with a liquid-solid ratio of 15mL / g are supplemented once every 30min; a single supplement amount of the intermittently supplemented vanadium-chromium mud is 0.5 times the mass of the initial vanadium-chromium mud, and the intermittent supplementation is performed 5 times. After the reaction is completed, filtration is performed to obtain a vanadium-chromium leaching solution.

[0065] Example 4

[0066] The source of the vanadium-containing chromium mud used in this embodiment is the vanadium-containing chromium mud produced in the process of removing chromium from wastewater after vanadium precipitation in the sodium roasting process of vanadium slag, wherein the vanadium content is 16.36%, and the vanadium exists in the form of vanadium oxide. The chromium content is 17.29%, and the chromium exists in the form of chromium trioxide and chromium hydroxide.

[0067] This embodiment provides a method for extracting vanadium and chromium from vanadium and chromium-containing mud by autocatalytic enhancement of micro-nano bubbles in a sodium hydroxide solution. Figure 1 As shown, the method includes:

[0068] A 10wt% sodium hydroxide solution and a vanadium-chromium mud are mixed at a liquid-solid ratio of 12mL / g to obtain a mixed slurry, and oxygen is continuously introduced into the mixed slurry at a flow rate of 1.2L / min using an aeration device to form micro-nano oxygen-containing bubbles with a diameter of ≤100μm, and a synchronous reaction is carried out at 90°C for 8.3h, wherein the synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out simultaneously. During the reaction, a 10wt% sodium hydroxide solution and a vanadium-chromium mud with a liquid-solid ratio of 12mL / g are supplemented once every 45min; a single supplement amount of the intermittently supplemented vanadium-chromium mud is 1.5 times the mass of the initial vanadium-chromium mud, and the intermittent supplementation is performed 10 times. After the reaction is completed, the vanadium-chromium leaching solution is obtained by filtering.

[0069] Example 5

[0070] The source of the vanadium-containing chromium mud used in this embodiment is the vanadium-containing chromium mud produced in the process of removing chromium from wastewater after vanadium precipitation in the sodium roasting process of vanadium slag, wherein the vanadium content is 13.25%, and the vanadium exists in the form of vanadium oxide and vanadium hydroxide. The chromium content is 18.74%, and the chromium exists in the form of chromium trioxide.

[0071] This embodiment provides a method for extracting vanadium and chromium from vanadium and chromium-containing mud by autocatalytic enhancement of micro-nano bubbles in a sodium hydroxide solution. Figure 1 As shown, the method includes:

[0072] A 20wt% sodium hydroxide solution and a vanadium-chromium mud are mixed at a liquid-solid ratio of 7mL / g to obtain a mixed slurry, and oxygen-enriched air with a flow rate of 0.1L / min is continuously introduced into the mixed slurry by an aeration device to form micro-nano oxygen-containing bubbles with a diameter of ≤2μm, and a synchronous reaction is carried out at 80°C for 9h, wherein the synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction carried out simultaneously, and during the reaction, a 10wt% sodium hydroxide solution and a vanadium-chromium mud with a liquid-solid ratio of 7mL / g are supplemented once every 90min; a single supplement amount of the intermittently supplemented vanadium-chromium mud is 1 times the mass of the initial vanadium-chromium mud, and the intermittent supplementation is performed 5 times. After the reaction is completed, the vanadium-chromium leaching solution is obtained by filtration.

[0073] Example 6

[0074] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud by using micro-nano bubbles in an alkaline solution. The method is the same as that of Embodiment 1 except that the concentration of the sodium hydroxide solution is 2 wt %.

[0075] Example 7

[0076] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium and chromium-containing mud by micro-nano bubbles in a sodium hydroxide solution. The method is the same as that of Embodiment 1 except that the sodium hydroxide solution is replaced by a potassium hydroxide solution.

[0077] Example 8

[0078] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-chromium-containing mud in an alkaline solution by using micro-nano bubbles. The method is the same as that in Embodiment 1 except that the synchronous reaction temperature is 40°C.

[0079] Example 9

[0080] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-chromium-containing mud in an alkaline solution by using micro-nano bubbles. The method is the same as that in Embodiment 1 except that the synchronous reaction temperature is 110°C.

[0081] Example 10

[0082] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud in an alkaline solution by using micro-nano bubbles to enhance the size of the micro-nano oxygen-containing bubbles, which is the same as that of embodiment 1 except that the size of the micro-nano oxygen-containing bubbles is 10-100 μm.

[0083] Embodiment 11

[0084] The present embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud in an alkaline solution by using micro-nano bubbles to enhance the extraction of vanadium and chromium from vanadium-containing chromium mud. The method is the same as that of Embodiment 1 except that the single replenishment amount of the vanadium-containing chromium mud in the intermittent replenishment is 0.1 times the mass of the initial vanadium-containing chromium mud.

[0085] Example 12

[0086] The present embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud in an alkaline solution by using micro-nano bubbles to enhance the extraction of vanadium and chromium from vanadium-containing chromium mud. The method is the same as that of Embodiment 1 except that the single replenishment amount of the vanadium-containing chromium mud in the intermittent replenishment is 2.5 times the mass of the initial vanadium-containing chromium mud.

[0087] Example 13

[0088] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium- and chromium-containing mud by using micro-nano bubbles in an alkaline solution. The method is the same as that of Embodiment 1 except that the flow rate of oxygen is 0.1 L / min.

[0089] Embodiment 14

[0090] This embodiment provides a method for the self-catalytic extraction of vanadium and chromium from vanadium- and chromium-containing mud by using micro-nano bubbles in an alkaline solution. The method is the same as that of Embodiment 1 except that the flow rate of oxygen is 2 Lmi / n.

[0091] Comparative Example 1

[0092] This comparative example provides a method for extracting vanadium and chromium from vanadium-chromium mud. The method is the same as Example 1 except that oxygen is directly introduced instead of introducing micro-nano oxygen-containing bubbles through an aeration device.

[0093] In this comparative example, since micro-nano oxygen-containing bubbles were not introduced, hydrogen peroxide and hydroxyl radicals with higher oxidation activity could not be generated during the alkali leaching process, so the extraction rates of vanadium and chromium were reduced.

[0094] Comparative Example 2

[0095] This comparative example provides a method for extracting vanadium and chromium from vanadium-chromium mud, which is the same as Example 1 except that oxygen is not introduced.

[0096] In this comparative example, since no oxygen is introduced and there is no oxidant in the system, only soluble pentavalent vanadium and hexavalent chromium in the vanadium-chromium mud enter the solution, and low-valent vanadium and chromium are not leached, so the extraction rate of vanadium and chromium is reduced.

[0097] Comparative Example 3

[0098] This comparative example provides a method for the self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud by using micro-nano bubbles in an alkaline solution. The method does not intermittently replenish the alkaline solution and the vanadium-containing chromium mud, and the rest is the same as Example 1.

[0099] Since the vanadium-containing chromium mud was not supplemented in this comparative example, the concentration of trivalent chromium with Fenton-like catalytic activity in the medium could not be maintained at a certain level during the alkali leaching process, resulting in the inability to subsequently catalyze hydrogen peroxide to generate hydroxyl radicals with higher oxidative activity, so the extraction rate of vanadium and chromium was reduced.

[0100] Comparative Example 4

[0101] This comparative example provides a method for extracting vanadium and chromium from vanadium-chromium mud. The method is the same as Example 1 except that micro-nano oxygen-containing bubbles are not introduced and alkali solution and vanadium-chromium mud are not supplemented.

[0102] In this comparative example, since no micro-nano oxygen-containing bubbles are introduced and no alkali solution and vanadium-chromium mud are supplemented, no oxygen and strong oxidizing active substances are generated, and vanadium and chromium in the vanadium-chromium mud are difficult to oxidize and leach, so the extraction rate of vanadium and chromium is greatly reduced.

[0103] Comparative Example 5

[0104] This comparative example provides a method for extracting vanadium from an alkaline solution. The method is the same as Example 1 except that the vanadium-containing chromium mud is replaced by vanadium slag.

[0105] In this comparative example, since the chromium in the vanadium slag mainly exists in the form of ferrochrome spinel, which is difficult to dissolve in alkaline solution to form a form that can catalyze Fenton-like reactions, only a small amount of vanadium in the vanadium slag is leached under the oxidation of oxygen, so the extraction rate of vanadium and chromium is greatly reduced.

[0106] Test Method

[0107] The mass of the tailings and the vanadium and chromium contents 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 contents of each element therein. The results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] The test results show that:

[0112] (1) It can be seen from Examples 1-5 and Example 7 that the method for extracting vanadium and chromium from vanadium-containing chromium mud by self-catalytic extraction of vanadium and chromium by micro-nano bubbles in an alkaline solution provided by the present invention can achieve good extraction of vanadium and chromium, with a vanadium extraction rate of ≥92% and a chromium extraction rate of ≥90%, and high process economy.

[0113] (2) It can be seen from Examples 1 and 6 that the sodium hydroxide concentration in Example 1 is 5 wt %. Compared with the sodium hydroxide concentration in Example 6 being 2 wt %, the vanadium extraction rate in Example 1 is 99%, and the chromium extraction rate is 95%, while the vanadium extraction rate in Example 6 is 82%, and the chromium extraction rate is 73%. This indicates that the present invention achieves higher vanadium and chromium extraction rates by further controlling the alkali concentration within the preferred range.

[0114] (3) It can be seen from Examples 1 and 7 that by changing the alkaline solution from sodium hydroxide to potassium hydroxide, the extraction rate of vanadium remains unchanged, and the extraction rate of chromium increases by 3%. However, considering that the price of potassium hydroxide is higher than that of sodium hydroxide, and the market demand for sodium salt products is much higher than that for potassium salt products, the alkaline solution is preferably a sodium hydroxide solution.

[0115] (4) It can be seen from Example 1 and Examples 8-9 that the alkali leaching temperature in Example 1 is 95°C, the temperature of the simultaneous reaction in Example 8 is 40°C, and the temperature of the simultaneous reaction in Example 9 is 110°C. The vanadium extraction rate in Example 1 is 99%, and the chromium extraction rate is 95%, the vanadium extraction rate in Example 8 is 88%, and the chromium extraction rate is 68%, and the vanadium extraction rate in Example 9 is 96%, and the chromium extraction rate is 90%. This shows that the present invention further controls the alkali leaching temperature within the preferred range, so that the reaction temperature satisfies the preferred temperature of the Fenton-like reaction and the alkali leaching reaction at the same time, thereby obtaining a higher vanadium and chromium extraction rate.

[0116] (5) It can be seen from Examples 1 and 10 that the diameter of the micro-nano oxygen-containing bubbles introduced in Example 1 is ≤5 μm, and the diameter of the micro-nano oxygen-containing bubbles introduced in Example 10 is 10-100 μm. The vanadium extraction rate in Example 1 is 99%, and the chromium extraction rate is 95%. The vanadium extraction rate in Example 10 is 94%, and the chromium extraction rate is 85%. This shows that the present invention further controls the size of the introduced micro-nano oxygen-containing bubbles within a preferred range, and the extraction rates of vanadium and chromium are higher.

[0117] (6) It can be seen from Example 1 and Examples 11 to 14 that the present invention further preferably intermittently supplements the amount of vanadium-containing chromium mud so that the content of trivalent chromium in the slurry system maintains a relative dynamic balance to adapt to the conditions of the Fenton-like reaction and promote the oxidation and leaching of vanadium and chromium. When the single supplement amount of vanadium-containing chromium mud is 0.1 times the mass of the initial vanadium-containing chromium mud, the amount of trivalent chromium is insufficient to self-catalyze the Fenton-like reaction, the vanadium extraction rate decreases from 99% in Example 1 to 90% in Example 11, and the chromium extraction rate decreases from 95% to 78%. When the single supplement amount of vanadium-containing chromium mud is 2.5 times the mass of the initial vanadium-containing chromium mud, vanadium and chromium cannot be fully oxidized and leached during the interval time, the vanadium extraction rate decreases to 73%, and the chromium extraction rate decreases to 61%. The gas flow rate is preferably continuously introduced so that the amount of micro-nano oxygen-containing bubbles introduced is sufficient to generate a large amount of peroxygen ions, and the oxygen therein can be fully utilized in the oxidation reaction to improve the utilization rate of the oxidizing gas. When the oxygen flow rate is 0.1 L / min, the micro-nano oxygen-containing bubbles generated are insufficient, the vanadium extraction rate drops to 66%, and the chromium extraction rate drops to 49%. When the oxygen flow rate is 2 L / min, the extraction rates of vanadium and chromium are not improved compared with Example 1, resulting in a waste of oxidizing gas.

[0118] (7) It can be seen from Example 1 and Comparative Examples 1-2 that Example 1 uses micro-nano oxygen-containing bubbles to pass into the reaction slurry, compared with Comparative Example 1 in which oxygen is directly passed without passing micro-nano oxygen-containing bubbles, and Comparative Example 2 in which oxygen-containing gas is not passed, the extraction rate of vanadium in Example 1 is 99%, and the extraction rate of chromium is 95%, the extraction rate of vanadium in Comparative Example 1 is 46%, and the extraction rate of chromium is 9%, and the extraction rate of vanadium in Comparative Example 2 is 5%, and the extraction rate of chromium is 1%. This shows that the introduction of micro-nano oxygen-containing bubbles improves the extraction rates of vanadium and chromium, that is, the present invention utilizes hydrogen peroxide generated during the bursting of micro-nano oxygen-containing bubbles to promote the self-catalytic Fenton-like reaction of vanadium-containing chromium mud, thereby significantly improving the extraction rates of vanadium and chromium.

[0119] (8) It can be seen from Example 1 and Comparative Example 3 that Example 1 adopts the method of supplementing a certain amount of alkaline solution and vanadium-containing chromium mud at regular intervals. Compared with Comparative Example 3 in which no alkaline solution and vanadium-containing chromium mud are supplemented, the vanadium extraction rate in Example 1 is 99%, and the chromium extraction rate is 95%. The vanadium extraction rate in Comparative Example 3 is 53%, and the chromium extraction rate is 16%. This shows that the supplemented vanadium-containing chromium mud ensures the continuous occurrence of Fenton-like reactions, thereby ensuring the continuous generation of hydroxyl radicals in the system, thereby improving the extraction rates of vanadium and chromium.

[0120] (9) It can be seen from Example 1 and Comparative Example 4 that Example 1 uses micro-nano bubbles to enhance leaching, and supplements a certain amount of alkaline solution and vanadium-containing chromium mud at regular intervals. Compared with Comparative Example 4 in which no micro-nano bubbles are introduced and no alkaline solution and vanadium-containing chromium mud are supplemented, the vanadium extraction rate in Example 1 is 99%, and the chromium extraction rate is 95%. The vanadium extraction rate in Comparative Example 4 is 45%, and the chromium extraction rate is 2%. This shows that the vanadium and chromium extraction rates are significantly improved under the strengthening effect of micro-nano bubbles and the continuous addition of Fenton-like catalysts. That is, the present invention introduces micro-nano bubbles on the one hand, and utilizes the hydrogen peroxide generated during the bursting of micro-nano bubbles to enhance the oxidation of vanadium and chromium in the vanadium-containing chromium mud. On the other hand, by continuously supplementing the vanadium-containing chromium mud, a stable supply of Fenton-like catalysts is guaranteed, thereby ensuring the stable generation of hydroxyl radicals with strong oxidizing activity, thereby improving the extraction rates of vanadium and chromium.

[0121] (10) It can be seen from Example 1 and Comparative Example 5 that when the raw material used in Comparative Example 5 is vanadium slag that does not contain soluble trivalent chromium, the autocatalytic Fenton-like reaction cannot occur and the vanadium extraction rate is greatly reduced.

[0122] In summary, the method for self-catalytic extraction of vanadium and chromium from vanadium-containing chromium mud by using micro-nano bubbles in an alkaline solution provided by the present invention adopts a sodium hydroxide solution as a leaching agent, and introduces micro-nano bubbles to generate strong oxidizing active oxygen substances to effectively promote the oxidation reaction of vanadium and chromium compounds in the vanadium-containing chromium mud, thereby improving the extraction rate of vanadium and chromium. Further, by using a specific sodium hydroxide concentration, micro-nano bubble size, and oxidation leaching reaction temperature, under optimal conditions, the extraction rate of vanadium is above 92%, and the extraction rate of chromium is above 90%, with high economic benefits.

[0123] 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 extracting vanadium and chromium from vanadium-chromium mud by autocatalysis enhanced by micro-nano bubbles in an alkaline solution, characterized in that: The method comprises: Micro-nano oxygen-containing bubbles are introduced into a mixed slurry of an alkali solution and vanadium-chromium mud to carry out a synchronous reaction, wherein the synchronous reaction includes a Fenton-like reaction and an alkali leaching reaction, and the alkali solution and the vanadium-chromium mud are intermittently replenished during the synchronous reaction to obtain a vanadium-chromium leaching solution.

2. The method according to claim 1, characterized in that The vanadium content of the vanadium-containing chrome mud is 1 to 30 wt%; Preferably, the valence state of vanadium in the vanadium-containing chromium mud includes trivalent and / or tetravalent.

3. The method according to claim 1 or 2, characterized in that: The chromium content of the vanadium-containing chromium mud is 5 to 30 wt%; Preferably, the valence state of chromium in the vanadium-containing chromium mud includes trivalent.

4. The method according to any one of claims 1 to 3, characterized in that: The alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution, preferably a sodium hydroxide solution; Preferably, the concentration of the alkaline solution is 2 to 40 wt%, preferably 5 to 20 wt%.

5. The method according to any one of claims 1 to 4, characterized in that: The liquid-to-solid ratio of the alkaline solution to the vanadium-containing chromium mud is 3-15 mL / g, preferably 7-12 mL / g.

6. The method according to any one of claims 1 to 5, characterized in that: The diameter of the micro-nano oxygen-containing bubbles is ≤100 μm, preferably ≤5 μm.

7. The method according to any one of claims 1 to 6, characterized in that: The gas of the micro-nano oxygen-containing bubbles is any one of air, oxygen-enriched air or oxygen, or a combination of at least two of them; Preferably, the method of introducing micro-nano oxygen-containing bubbles is continuous introduction; Preferably, the continuous introduction uses an aeration device; Preferably, the continuous flow rate is 0.1 to 1.5 L / min.

8. The method according to any one of claims 1 to 7, characterized in that: The interval time of intermittent supplementation is 30 to 90 minutes, preferably 30 to 60 minutes; Preferably, the single replenishment amount of the vanadium-containing chromium mud in the intermittent replenishment is 0.5 to 2 times the mass of the initial vanadium-containing chromium mud, preferably 0.5 to 1 times; Preferably, the concentration of the alkaline solution in the intermittent supplementation is 2 to 40 wt%, preferably 5 to 20 wt%; Preferably, the liquid-to-solid ratio of the intermittently supplemented alkali solution and the vanadium-containing chromium mud is 3 to 15 mL / g, preferably 7 to 12 mL / g; Preferably, the number of intermittent supplementation is 3 to 10 times, preferably 3 to 6 times.

9. The method according to any one of claims 1 to 8, characterized in that: The temperature of the synchronous reaction is 40-100°C, preferably 70-100°C; Preferably, the synchronous reaction time is 2 to 12 hours.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises: An aeration device is used to continuously introduce oxygen-containing gas with a flow rate of 0.1 to 1.5 L / min into a mixed slurry of an alkaline solution with a concentration of 2 to 40 wt% and vanadium-containing chromium mud to form micro-nano oxygen-containing bubbles with a diameter of ≤100 μm, and a synchronous reaction is carried out at 40 to 100° C. for 2 to 17 hours. The synchronous reaction includes a Fenton-like reaction and an alkaline leaching reaction that are carried out simultaneously. The liquid-to-solid ratio of the alkaline solution to the vanadium-containing chromium mud is 3 to 15 mL / g. During the synchronous reaction, the alkaline solution with a concentration of 2 to 40 wt% and the vanadium-containing chromium mud with a liquid-to-solid ratio of 3 to 15 mL / g are supplemented once every 30 to 90 minutes. The single supplement amount of the vanadium-containing chromium mud is 0.5 to 2 times the mass of the initial vanadium-containing chromium mud, and the number of intermittent supplements is 3 to 10 times to obtain a vanadium-containing chromium leaching solution.

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