Method for extracting vanadium element from chlorination process titanium dioxide dust collection slag

Abstract

The invention provides a method for extracting a vanadium element from chlorination process titanium dioxide dust collection slag, and belongs to the technical field of resources and environments. The method comprises the following steps: mixing the chlorination process titanium dioxide dust collection slag, a reducing auxiliary agent, acid and water to obtain acidic mixed slurry; the acid environment can inhibit interference of hetero-ion precipitation, pentavalent vanadium of the chlorination process titanium dioxide dust collection slag can be converted into tetravalent vanadium, the selectivity of vanadium during extraction is improved, and then the recovery efficiency of vanadium is improved. The leaching solution and the compound organic phase are mixed for extraction, an alcohol solvent or a neutral organic phosphorus extraction agent in the extraction improver in the compound organic phase can prevent the emulsification phenomenon during extraction, phase splitting is facilitated, and the vanadium extraction effect is improved. According to the method, the vanadium-containing strip liquor is mixed with the oxidizing agent and the ammonium salt, ammonium metavanadate precipitates or ammonium polyvanadate precipitates are obtained during oxidation and vanadium precipitation, and then a vanadium product is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of resources and environment, in particular to a method for extracting vanadium from titanium dioxide dust collected by a chloride process. Background Art

[0002] Titanium dioxide is an important chemical raw material and plays a crucial role in the national economy. The chloride process is the primary process for producing titanium dioxide, offering advantages such as high-quality titanium dioxide. However, the production process is accompanied by the generation of large amounts of chloride-process titanium dioxide dust residue. Currently, the conventional method for disposing of chloride-process titanium dioxide dust residue is landfill. However, chloride-process titanium dioxide dust residue primarily consists of unreacted titanium-rich slag and petroleum coke. It also contains ferric chloride, ferrous chloride, and small amounts of metal chlorides such as aluminum chloride, manganese chloride, and magnesium chloride, produced by the chlorination reaction. It also contains a variety of high-value precious metals such as vanadium, scandium, zirconium, and niobium. Landfilling chloride-process titanium dioxide dust residue not only occupies land and wastes resources, but also poses environmental concerns such as soil and groundwater contamination caused by the leaching of metal elements.

[0003] Vanadium is a vital resource, and vanadium pentoxide is widely used in metallurgy, chemical engineering, aerospace, atomic energy, and vanadium batteries. Therefore, recovering vanadium from chloride-process titanium dioxide dust residue is of great significance. However, the composition of chloride-process titanium dioxide dust residue is complex, typically containing multiple elements such as vanadium, iron, aluminum, silicon, calcium, and magnesium, as well as impurities such as chlorine, sulfur, and phosphorus. This makes the separation and purification of vanadium difficult, resulting in low recovery rates. Summary of the Invention

[0004] The object of the present invention is to provide a method for extracting vanadium from titanium dioxide dust collected by chloride process with high vanadium recovery rate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for extracting vanadium from titanium dioxide dust collected by a chloride process, comprising the following steps: (1) mixing titanium dioxide dust collection residue from the chloride process, a reducing agent, an acid and water to obtain an acidic mixed slurry, and subjecting the acidic mixed slurry to reduction leaching to obtain leaching residue and a leachate; (2) mixing the leachate obtained in step (1) with the composite organic phase and performing extraction to obtain an organic extract phase and an aqueous phase; The composite organic phase includes a vanadium extractant, an extraction improver and a diluent; (3) mixing the organic extract phase obtained in step (2) with a soluble alkali salt solution and performing stripping to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with an oxidant and an ammonium salt, and vanadium precipitation and solid-liquid separation are sequentially performed to obtain a vanadium product.

[0006] Preferably, the mass ratio of the chloride process titanium dioxide dust collection residue to water in step (1) is 1:1-15.

[0007] Preferably, the reducing aid in step (1) includes one or more of sodium formate, sodium sulfite, sodium thiosulfate and hydrogen peroxide.

[0008] Preferably, the pH value of the acidic mixed slurry in step (1) is 1.2-2.5.

[0009] Preferably, the reduction leaching temperature in step (1) is 45-80° C., and the reduction leaching time is 0.5-6 h.

[0010] Preferably, the vanadium extractant in step (2) includes one or more of an acidic phosphorus extractant, an amine extractant, a quaternary ammonium salt extractant, a composite extractant, a neutral oxygen-containing extractant and a chelating extractant.

[0011] Preferably, the alcohol solvent in step (2) includes one or more of octanol and isoamyl alcohol; and the neutral organophosphorus extractant is tributyl phosphate.

[0012] Preferably, the volume ratio of the vanadium extractant, the extraction improver and the diluent in step (2) is (1-2): (1-2): (7-8).

[0013] Preferably, the oxidant in step (4) includes one or more of hydrogen peroxide, sodium hypochlorite and ozone.

[0014] Preferably, the temperature of the oxidation precipitation of vanadium in step (4) is 80-100°C.

[0015] The present invention provides a method for extracting vanadium from titanium dioxide dust residue collected by the chloride process, comprising the following steps: mixing the titanium dioxide dust residue collected by the chloride process, a reducing agent, an acid, and water to obtain an acidic mixed slurry; subjecting the acidic mixed slurry to reduction leaching to obtain a leached residue and a leachate; mixing the leachate with a composite organic phase and extracting to obtain an organic extract phase and an aqueous phase; the composite organic phase comprises a vanadium extractant, an extraction improver, and a diluent; mixing the organic extract phase with a soluble alkali salt solution and stripping to obtain a vanadium-containing stripping solution and an organic phase; mixing the vanadium-containing stripping solution with an oxidant and an ammonium salt, and sequentially subjecting the stripping solution to vanadium oxidation precipitation and solid-liquid separation to obtain a vanadium product. The present invention obtains an acidic mixed slurry by mixing the titanium dioxide dust residue collected by the chloride process, a reducing agent, an acid, and water. During reduction leaching, the acidic environment can inhibit the precipitation or interference of impurity ions and can also convert pentavalent vanadium in the titanium dioxide dust residue into tetravalent vanadium, thereby improving the selectivity of vanadium during extraction, reducing impurity interference, and thereby improving the recovery efficiency of vanadium. The present invention extracts by mixing a leachate with a composite organic phase. The alcohol solvent or neutral organophosphorus extractant in the extraction improver in the composite organic phase prevents emulsification during extraction, facilitates phase separation, and improves the extraction efficiency of vanadium. The present invention strips the organic extract phase by mixing it with a soluble alkali salt solution, transferring the vanadium element to a vanadium-containing stripping solution. The present invention mixes the vanadium-containing stripping solution with an oxidant and an ammonium salt, and upon oxidation and precipitation of the vanadium, produces an ammonium metavanadate precipitate or an ammonium polyvanadate precipitate, thereby obtaining a vanadium product. The results of the examples show that the method provided by the present invention can achieve a vanadium leaching rate of over 92% and an extraction rate of over 91%, with a high vanadium recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the process for extracting vanadium from titanium dioxide dust collected by the chloride process according to Examples 1 to 3 of the present invention. DETAILED DESCRIPTION

[0017] The present invention provides a method for extracting vanadium from titanium dioxide dust collected by a chloride process, comprising the following steps: (1) mixing titanium dioxide dust collection residue from the chloride process, a reducing agent, an acid and water to obtain an acidic mixed slurry, and subjecting the acidic mixed slurry to reduction leaching to obtain leaching residue and a leachate; (2) mixing the leachate obtained in step (1) with the composite organic phase and performing extraction to obtain an organic extract phase and an aqueous phase; The composite organic phase includes a vanadium extractant, an extraction improver and a diluent; the extraction improver includes an alcohol solvent or a neutral organophosphorus extractant; (3) mixing the organic extract phase obtained in step (2) with a soluble alkali salt solution and performing stripping to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with an oxidant and an ammonium salt, and vanadium precipitation and solid-liquid separation are sequentially performed to obtain a vanadium product.

[0018] The invention mixes chloride titanium dioxide dust collecting residue, a reducing agent, acid and water to obtain an acidic mixed slurry, and performs reduction leaching on the acidic mixed slurry to obtain leached residue and leaching liquid.

[0019] The present invention has no special limitation on the source of the titanium dioxide dust residue collected by the chloride process, and conventional titanium dioxide dust residue collected by the chloride process can be used.

[0020] In the present invention, the reducing aid preferably includes one or more of sodium formate, sodium sulfite, sodium thiosulfate, and hydrogen peroxide, more preferably sodium formate, sodium sulfite, or hydrogen peroxide. Using these reducing aids, the present invention generates the reaction: 2VOCl3 + Na2SO3 + H2O → 2VOCl2 + Na2SO4 + 2HCl, which converts pentavalent vanadium into tetravalent vanadium, improving vanadium selectivity during extraction and thereby increasing vanadium recovery efficiency. Using these reducing aids, the present invention exhibits a superior vanadium reduction effect.

[0021] In the present invention, the acid preferably includes one or more of hydrochloric acid, sulfuric acid, and phosphoric acid, more preferably hydrochloric acid. The present invention uses an acid to adjust the pH value of the mixed slurry to obtain an acidic mixed slurry. The present invention does not particularly limit the concentration of the acid; any acid of a conventional concentration that can bring the pH value of the mixed slurry to the desired range can be used. In the present invention, the mass concentration of the acid is preferably 32-36%.

[0022] In the present invention, the mass ratio of the titanium dioxide chloride dust collection residue to water is preferably 1:1 to 15. As one embodiment of the present invention, the mass ratio of the titanium dioxide chloride dust collection residue to water can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15. The present invention controls the mass ratio of titanium dioxide chloride dust collection residue to water within the above range, which has better fluidity and is more conducive to increasing the vanadium leaching rate. In the embodiments of the present invention, the mass ratio of titanium dioxide chloride dust collection residue to water is simply referred to as the solid-liquid ratio.

[0023] In the present invention, the pH value of the acidic mixed slurry is preferably 1.2 to 2.5, more preferably 1.5 to 2. The present invention controls the pH value of the acidic mixed slurry within the above range, which is more conducive to suppressing the precipitation or interference of foreign ions, thereby improving the purity of vanadium in the vanadium product.

[0024] In the present invention, the molar ratio of vanadium in the chloride process titanium dioxide dust collection slag to the reducing agent is preferably 1:1 to 1.5, and more preferably 1:1.2 to 1.3. By controlling the molar ratio of vanadium in the chloride process titanium dioxide dust collection slag to the reducing agent within the above range, the pentavalent vanadium in the chloride process titanium dioxide dust collection slag can be fully reduced to tetravalent vanadium.

[0025] The present invention does not specifically limit the method for mixing the chloride titanium dioxide dust collection residue, reducing agent, acid, and water, as long as a uniformly mixed acidic mixed slurry is formed. In an embodiment of the present invention, the mixing method may include slurrying the chloride titanium dioxide dust collection residue and water to obtain a slurry, adding an acid to the slurry to adjust the pH, then adding the reducing agent, and mixing to obtain the acidic mixed slurry. In the present invention, the pH value is the pH value of the acidic mixed slurry.

[0026] In the present invention, the reduction leaching temperature is preferably 45 to 80°C. As an embodiment of the present invention, the reduction leaching temperature may be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C. In the present invention, the reduction leaching time is preferably 0.5 to 6 hours. As an embodiment of the present invention, the reduction leaching time may be 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours. The present invention, at the above temperature and time, is more conducive to fully converting pentavalent vanadium into tetravalent vanadium and fully leaching it.

[0027] In the present invention, the reduction leaching is preferably carried out under stirring. Stirring can promote solid-liquid mass transfer and improve the leaching effect of vanadium ions. The present invention does not specifically limit the stirring speed.

[0028] The present invention preferably performs solid-liquid separation on the system obtained by the reduction leaching to obtain a leach residue and a leachate. The present invention does not particularly limit the method of the solid-liquid separation, and any conventional solid-liquid separation method can be used. In an embodiment of the present invention, the solid-liquid separation method can be plate and frame filter pressing.

[0029] After obtaining the leachate, the present invention mixes the leachate with the composite organic phase and performs extraction to obtain an organic extraction phase and an aqueous phase.

[0030] In the present invention, the composite organic phase includes a vanadium extractant, an extraction improver and a diluent.

[0031] In the present invention, the vanadium extractant preferably includes one or more of an acidic phosphorus extractant, an amine extractant, a quaternary ammonium salt extractant, a composite extractant, a neutral oxygen-containing extractant, and a chelating extractant. In the present invention, the acidic phosphorus extractant is preferably di(2-ethylhexyl) phosphate (codenamed P204) and / or 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (codenamed P507); the amine extractant is preferably a linear (C19-C23) saturated primary amine (codenamed N1923) and / or a trialkylamine (C8-C10) (codenamed N235); the quaternary ammonium salt extractant is preferably trioctylmethylammonium chloride (codenamed N263); the composite extractant is preferably a mixed long-chain (C7-C9) carboxylic acid extractant (codenamed LK-N21); the neutral oxygen-containing extractant is preferably methyl isobutyl ketone (codenamed MIBK); and the chelating extractant is preferably a bifunctional modified phosphonate extractant (codenamed C902). The present invention utilizes these vanadium extractants to achieve excellent extraction of vanadium ions.

[0032] In the present invention, the extraction improver includes an alcohol solvent or a neutral organophosphorus extractant. In the present invention, the alcohol solvent preferably includes one or more of octanol and isoamyl alcohol; the neutral organophosphorus extractant is preferably tributyl phosphate, abbreviated as TBP. The present invention uses the above-mentioned extraction improver to prevent emulsification during extraction, facilitate phase separation, and improve vanadium extraction efficiency. In the present invention, the diluent preferably includes one or more of sulfonated kerosene, 206# kerosene, 260# kerosene and solvent white oil. The present invention is more conducive to promoting phase separation by adding the diluent.

[0033] In the present invention, the volume ratio of the vanadium extractant, the extraction improver, and the diluent is preferably (1-2):(1-2):(7-8). In an embodiment of the present invention, the volume ratio of the vanadium extractant, the extraction improver, and the diluent may be 1:2:7, 1:1:8, or 2:1:7.

[0034] In the present invention, the volume ratio of the composite organic phase to the leachate is preferably 1:1 to 10. As one embodiment of the present invention, the volume ratio of the composite organic phase to the leachate can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. Controlling the volume ratio of the composite organic phase to the leachate within the above range is more conducive to fully extracting vanadium ions in the leachate into the organic extraction phase.

[0035] In the present invention, the volume ratio of the leachate to the composite organic phase is preferably 1:1-3, more preferably 1:1.2-2.5.

[0036] The present invention has no particular limitation on the method of mixing the leachate with the composite organic phase, as long as the two are mixed uniformly. In the present invention, the method of mixing the leachate with the composite organic phase is preferably stirring.

[0037] The present invention does not particularly limit the extraction method, and conventional liquid-liquid extraction methods can be used. In an embodiment of the present invention, the extraction is preferably carried out in an extraction tank. The extraction method can be to mix the leachate and the composite organic phase in the extraction tank, stir, and then stand for phase separation to obtain an organic extract phase and an aqueous phase.

[0038] After obtaining the organic extraction phase and the aqueous phase, the present invention mixes the organic extraction phase with a soluble alkali salt solution and performs stripping to obtain a vanadium-containing stripping solution and an organic phase.

[0039] In the present invention, the aqueous phase is preferably used as water to mix with the chloride process titanium dioxide dust collection residue, a reducing agent, and an acid. In the present invention, the aqueous phase is mixed with the chloride process titanium dioxide dust collection residue, a reducing agent, and an acid to replace part of the water used for reduction leaching of the next batch of chloride process titanium dioxide dust collection residue, thereby reducing the generation of wastewater.

[0040] In the present invention, the soluble alkali salt solution preferably includes one or more of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, potassium carbonate solution, ammonia water, sodium chloride solution and potassium chloride solution, more preferably sodium hydroxide solution, potassium hydroxide solution or sodium carbonate solution. In the present invention, the mass concentration of the soluble alkali salt solution is preferably 8-12%. As an embodiment of the present invention, the mass concentration of the soluble alkali salt solution can be 8%, 9%, 10%, 11% or 12%. The present invention uses a soluble alkali salt solution as a stripping agent, which can transfer vanadium ions in the organic extract phase to a vanadium-containing stripping solution. Controlling the mass concentration of the soluble alkali salt solution within the above range is more conducive to improving the stripping effect of vanadium.

[0041] In the present invention, when the mass concentration of the soluble alkali salt solution is 8-12%, the volume ratio of the organic extract phase to the soluble alkali salt solution is preferably (1-5):(1-3), more preferably (2-4):(1-2).

[0042] The present invention has no particular limitation on the method for mixing the organic extract phase with the soluble alkali salt solution, as long as the two are mixed uniformly. In the present invention, the method for mixing the organic extract phase with the soluble alkali salt solution is preferably stirring.

[0043] The present invention does not particularly limit the stripping method; conventional liquid-liquid extraction methods may be employed. In embodiments of the present invention, the stripping is preferably performed in a stripping tank. The stripping method may include mixing the organic extract phase with a soluble alkali salt solution in a stripping tank, stirring, and then allowing the mixture to stand for phase separation, thereby obtaining a vanadium-containing stripping solution and an organic phase.

[0044] After obtaining the vanadium-containing stripping solution and the organic phase, the present invention mixes the vanadium-containing stripping solution with an oxidant and an ammonium salt, and sequentially performs oxidation precipitation of vanadium and solid-liquid separation to obtain a vanadium product.

[0045] The present invention preferably separates the vanadium-containing stripping solution from the organic phase and uses the organic phase as a composite organic phase. Using the organic phase as a composite organic phase can be used to mix the next batch of leachate with the composite organic phase for extraction, thereby recycling the organic phase and reducing wastewater generation.

[0046] In the present invention, the oxidant preferably includes one or more of hydrogen peroxide, sodium hypochlorite, and ozone, more preferably hydrogen peroxide or sodium hypochlorite. The oxidant can oxidize vanadium ions in the vanadium-containing strip solution, reacting with ammonium salts to form ammonium metavanadate precipitates or ammonium polyvanadate precipitates.

[0047] In the present invention, the ammonium salt preferably includes one or more of ammonium chloride, ammonium bicarbonate and ammonium sulfate, more preferably ammonium sulfate. The use of the ammonium salt in the present invention can cause the oxidized vanadium ions in the vanadium-containing stripping solution to form ammonium metavanadate precipitate or ammonium polyvanadate precipitate.

[0048] In the present invention, the molar ratio of vanadium ions to the oxidant and ammonium salt in the vanadium-containing strip solution is preferably 1:(1-1.2):(1-1.2). By controlling the molar ratio of the vanadium-containing strip solution to the oxidant and ammonium salt within the above range, the vanadium in the vanadium-containing strip solution can be fully precipitated.

[0049] The present invention does not particularly limit the method for mixing the vanadium-containing stripping solution, the oxidant, and the ammonium salt; the three can be uniformly mixed. In the present invention, the method for mixing the vanadium-containing stripping solution, the oxidant, and the ammonium salt is preferably as follows: after mixing the vanadium-containing stripping solution with the oxidant, heating the mixture to a temperature at which the vanadium precipitate is oxidized, and then mixing the mixture with the ammonium salt while stirring.

[0050] In the present invention, the temperature of the vanadium oxidation precipitation is preferably 80-100° C. As an embodiment of the present invention, the temperature of the vanadium oxidation precipitation can be 80° C., 85° C., 90° C., 95° C. or 100° C. The present invention has no particular limitation on the time of the vanadium oxidation precipitation, as long as no precipitation is generated.

[0051] The present invention has no particular limitation on the solid-liquid separation method. Conventional solid-liquid separation methods can be used to fully separate the solid and liquid in the vanadium oxide precipitation system. In an embodiment of the present invention, the solid-liquid separation method can be filter press.

[0052] The schematic flow chart of the method for extracting vanadium from titanium dioxide dust collected by the chloride process provided by the present invention is preferably as follows: Figure 1 As shown. Figure 1 It can be seen that the present invention mixes the dust residue (i.e., titanium dioxide dust residue from the chloride process) with an auxiliary agent (i.e., a reducing auxiliary agent) and hydrochloric acid, and then dissolves the mixture (i.e., reduction leaching), and then filters it to obtain waste residue (i.e., leaching residue) and a leachate; the leachate is mixed with an extractant (i.e., a composite organic phase) and then subjected to liquid extraction to obtain an organic extraction phase (organic phase) and an aqueous phase, and then the aqueous phase is reused as water for the next batch of reduction leaching; the organic phase is stripped, and the obtained organic phase is reused as a composite organic phase; the vanadium-containing stripping liquid is oxidized and precipitated with vanadium and filtered to obtain a solid vanadium product and a liquid wastewater.

[0053] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] Example 1 A method for extracting vanadium from titanium dioxide dust residue produced by a chloride process, comprising the following steps: (1) Chloride titanium dioxide dust collection residue and water are slurried at a solid-liquid ratio of 1:3 to obtain a slurry, hydrochloric acid is added to the slurry to adjust the pH value to 2.5, and then sodium formate as a reducing aid is added (the molar ratio of vanadium in the chloride titanium dioxide dust collection residue to sodium formate is 1:1.2), and after mixing, an acidic mixed slurry with a pH value of 2.5 is obtained, the acidic mixed slurry is heated to 70°C, stirred for 2 hours for reduction leaching, and then plate and frame filter pressing is performed to obtain leached residue and leachate; (2) the leachate obtained in step (1) is mixed with a composite organic phase (N235, TBP and sulfonated kerosene in a volume ratio of 1:2:7) in a volume ratio of 1:1, extracted in an extraction tank, stirred and allowed to stand for phase separation to obtain an organic extract phase and an aqueous phase; (3) mixing the organic extract obtained in step (2) with a sodium hydroxide solution having a mass concentration of 10% in a volume ratio of 1:1 in a stripping tank, stirring, and then standing to separate the phases to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with sodium hypochlorite, heated to 85° C., and then ammonium sulfate is added under stirring (the molar ratio of vanadium ions, sodium hypochlorite and ammonium sulfate in the vanadium-containing stripping solution is 1:1:1). Vanadium is oxidized and precipitated at 85° C. until no precipitate is generated, and then filtered to obtain a solid vanadium product.

[0055] Example 2 A method for extracting vanadium from titanium dioxide dust residue produced by a chloride process, comprising the following steps: (1) Chloride titanium dioxide dust collection residue and water are slurried at a solid-liquid ratio of 1:5 to obtain a slurry, acid is added to the slurry to adjust the pH value to 2.2, and then sodium sulfite as a reducing aid is added (the molar ratio of vanadium in the chloride titanium dioxide dust collection residue to sodium sulfite is 1:1), and after mixing, an acidic mixed slurry with a pH value of 2.2 is obtained, the acidic mixed slurry is heated to 65°C, stirred for 4 hours for reduction leaching, and then plate and frame filter pressing is performed to obtain leached residue and leachate; (2) The leachate obtained in step (1) is mixed with a composite organic phase (P204, TBP and 260# kerosene in a volume ratio of 1:1:8) in a volume ratio of 1:2, extracted in an extraction tank, stirred and allowed to stand for phase separation to obtain an organic extract phase and an aqueous phase; (3) mixing the organic extract obtained in step (2) with a sodium hydroxide solution having a mass concentration of 12% in a volume ratio of 1:1 in a stripping tank, stirring, and then standing to separate the phases to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with sodium hypochlorite, and the temperature is raised to 90° C., and then ammonium sulfate is added under stirring (the molar ratio of vanadium ions, sodium hypochlorite and ammonium sulfate in the vanadium-containing stripping solution is 1:1:1.2). Vanadium is oxidized and precipitated at 90° C. until no precipitate is generated, and then filter press is performed to obtain a solid vanadium product.

[0056] Example 3 A method for extracting vanadium from titanium dioxide dust residue produced by a chloride process, comprising the following steps: (1) Chloride titanium dioxide dust collection residue and water are slurried at a solid-liquid ratio of 1:4 to obtain a slurry, acid is added to the slurry to adjust the pH value to 2.3, and then a reducing aid hydrogen peroxide is added (the molar ratio of vanadium in the chloride titanium dioxide dust collection residue to hydrogen peroxide is 1:1), and after mixing, an acidic mixed slurry with a pH value of 2.3 is obtained, the acidic mixed slurry is heated to 60°C, stirred for 5 hours for reduction leaching, and then plate and frame filter pressing is performed to obtain leached residue and leachate; (2) the leachate obtained in step (1) is mixed with a composite organic phase (P204, P507, TBP and sulfonated kerosene in a volume ratio of 1:1:1:7) in a volume ratio of 1:2.5, extracted in an extraction tank, stirred and allowed to stand for phase separation to obtain an organic extract phase and an aqueous phase; (3) mixing the organic extract obtained in step (2) with a sodium hydroxide solution having a mass concentration of 8% in a volume ratio of 1:1 in a stripping tank, stirring, and then standing to separate the phases to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with sodium hypochlorite, heated to 95° C., and then ammonium sulfate is added (the molar ratio of vanadium ions, sodium hypochlorite and ammonium sulfate in the vanadium-containing stripping solution is 1:1:1.2). Vanadium is oxidized and precipitated at 95° C. until no precipitate is generated, and then filtered to obtain a solid vanadium product.

[0057] Comparative Example 1 A method for extracting vanadium from titanium dioxide dust residue produced by a chloride process, comprising the following steps: (1) slurrying the titanium dioxide dust collection residue from the chloride process and water at a solid-liquid ratio of 1:4 to obtain a slurry, adding acid to the slurry to adjust the pH value to obtain an acidic mixed slurry with a pH value of 2.3, heating the acidic mixed slurry to 60°C, stirring for 5 hours to leaching, and then performing plate and frame filter pressing to obtain leached residue and leachate; (2) the leachate obtained in step (1) is mixed with a composite organic phase (P204, P507, TBP, and sulfonated kerosene in a volume ratio of 1:1:1:7) in a volume ratio of 1:3, extracted in an extraction tank, stirred, and then allowed to stand for phase separation to obtain an organic extract phase and an aqueous phase; (3) mixing the organic extract obtained in step (2) with a sodium hydroxide solution having a mass concentration of 8% in a volume ratio of 1:1 in a stripping tank, stirring, and then standing to separate the phases to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with sodium hypochlorite, heated to 95° C., and then ammonium sulfate is added under stirring (the molar ratio of vanadium ions, sodium hypochlorite and ammonium sulfate in the vanadium-containing stripping solution is 1:1:1.2). Vanadium is oxidized and precipitated at 95° C. until no precipitate is generated, and then filtered to obtain a solid vanadium product.

[0058] Comparative Example 2 A method for extracting vanadium from titanium dioxide dust residue produced by a chloride process, comprising the following steps: (1) Chloride titanium dioxide dust collection residue and water are slurried at a solid-liquid ratio of 1:4 to obtain a slurry, acid is added to the slurry to adjust the pH value to 2.3, and then a reducing aid hydrogen peroxide is added (the molar ratio of vanadium in the chloride titanium dioxide dust collection residue to hydrogen peroxide is 1:1), and after mixing, an acidic mixed slurry with a pH value of 2.3 is obtained, the acidic mixed slurry is heated to 60°C, stirred for 5 hours for reduction leaching, and then plate and frame filter pressing is performed to obtain leached residue and leachate; (2) The leachate obtained in step (1) is mixed with a composite organic phase (P204, P507 and sulfonated kerosene in a volume ratio of 1:2:7) at a volume ratio of 1:1.5, extracted in an extraction tank, stirred and allowed to stand for phase separation to obtain an organic extract phase and an aqueous phase; (3) mixing the organic extract obtained in step (2) with a sodium hydroxide solution having a mass concentration of 8% in a volume ratio of 1:1 in a stripping tank, stirring, and then standing to separate the phases to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with sodium hypochlorite, heated to 95° C., and then ammonium sulfate is added (the molar ratio of vanadium ions, sodium hypochlorite and ammonium sulfate in the vanadium-containing stripping solution is 1:1:1.2). Vanadium is oxidized and precipitated at 95° C. until no precipitate is generated, and then filtered to obtain a solid vanadium product.

[0059] Test Case Elemental analysis was performed on the titanium dioxide dust collection residue and leaching residue used in step (1) of Examples 1 to 3 and Comparative Examples 1 to 2 to obtain the vanadium metal content. The leaching rate was then calculated as follows: leaching rate = 1 - vanadium content in leaching residue / vanadium content in dust collection residue. The results are shown in Table 1: Table 1 Vanadium leaching data of Examples 1-3 and Comparative Examples 1-2

[0060] As can be seen from Table 1, the method provided by the present invention has a higher leaching rate for vanadium in the dust collection residue of titanium dioxide produced by the chloride process. This is because the present invention performs reduction leaching on the acidic mixed slurry, converting the pentavalent vanadium in the dust collection residue of titanium dioxide produced by the chloride process into tetravalent vanadium, thereby improving the leaching rate.

[0061] Elemental analysis was performed on the leachate and aqueous phase obtained in steps (1) of Examples 1-3 and Comparative Examples 1-2 to determine the vanadium metal content. The extraction rate was then calculated as follows: extraction rate = 1 - vanadium content in aqueous phase / vanadium content in leachate. The results are shown in Table 2: Table 2 Extraction data of vanadium by the methods of Examples 1 to 3 and Comparative Examples 1 to 2

[0062] From the above results, it can be seen that the method provided by the present invention has a high extraction rate of vanadium in the leachate. This is because the present invention can improve the selectivity for vanadium and the extraction rate of vanadium by adopting a composite organic phase.

[0063] From the above results, it can be seen that the method provided by the present invention has a high leaching rate for vanadium in the dust collection residue of titanium dioxide produced by the chloride process, and has a high extraction rate for vanadium in the leachate, thereby significantly improving the recovery rate of vanadium in the dust collection residue of titanium dioxide produced by the chloride process, and the purity of vanadium reaches 98 metallurgical grade.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for extracting vanadium from titanium dioxide dust residue produced by the chloride process, characterized in that: The following steps are involved: (1) mixing titanium dioxide dust collection residue from the chloride process, a reducing agent, an acid and water to obtain an acidic mixed slurry, and subjecting the acidic mixed slurry to reduction leaching to obtain leaching residue and a leachate; (2) mixing the leachate obtained in step (1) with the composite organic phase and performing extraction to obtain an organic extract phase and an aqueous phase; The composite organic phase includes a vanadium extractant, an extraction improver and a diluent; the extraction improver includes an alcohol solvent or a neutral organophosphorus extractant; (3) mixing the organic extract phase obtained in step (2) with a soluble alkali salt solution and performing stripping to obtain a vanadium-containing stripping solution and an organic phase; (4) The vanadium-containing stripping solution obtained in step (3) is mixed with an oxidant and an ammonium salt, and vanadium precipitation and solid-liquid separation are sequentially performed to obtain a vanadium product.

2. The method according to claim 1, characterized in that The mass ratio of the titanium dioxide dust collection residue from the chloride process to water in the step (1) is 1:1-15.

3. The method according to claim 1, characterized in that The reducing aid in step (1) includes one or more of sodium formate, sodium sulfite, sodium thiosulfate and hydrogen peroxide.

4. The method according to claim 1, wherein The pH value of the acidic mixed slurry in step (1) is 1.2-2.

5.

5. The method according to claim 1, characterized in that The reduction leaching temperature in step (1) is 45-80° C., and the reduction leaching time is 0.5-6 h.

6. The method according to claim 1, characterized in that The vanadium extractant in step (2) includes one or more of an acidic phosphorus extractant, an amine extractant, a quaternary ammonium salt extractant, a composite extractant, a neutral oxygen-containing extractant, and a chelating extractant.

7. The method according to claim 1, characterized in that The alcohol solvent in step (2) includes one or more of octanol and isoamyl alcohol; and the neutral organophosphorus extractant is tributyl phosphate.

8. The method according to claim 1, characterized in that The volume ratio of the vanadium extractant, the extraction improver and the diluent in step (2) is (1-2): (1-2): (7-8).

9. The method according to claim 1, characterized in that The oxidant in step (4) includes one or more of hydrogen peroxide, sodium hypochlorite and ozone.

10. The method according to claim 1, characterized in that The temperature of the vanadium oxidation precipitation in step (4) is 80-100°C.

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