Method for preparing vanadium pentoxide by separating and extracting vanadium ions in vanadium slag

Abstract

The invention belongs to the technical field of vanadium ion extraction, and particularly relates to a method for preparing vanadium pentoxide by separating and extracting vanadium ions in vanadium slag. The invention discloses a method for preparing vanadium pentoxide by separating and extracting vanadium ions in vanadium slag. The method comprises the following steps: roasting and leaching the vanadium slag, and adjusting the pH value to obtain a first solution; adding a reducing agent into the first solution to obtain a second solution, and adding a complexing agent to complex impurity ions in the first solution to obtain a third solution; adding an extraction solvent into the third solution, washing the extracted organic phase, and adding a back extraction agent into the organic phase after washing to obtain a back extraction solution and a blank organic phase; ammonium salt is added into the strip liquor to precipitate vanadium ions in the strip liquor, and vanadium pentoxide with the purity of 99.9% is obtained through drying and calcination. By means of the method, the recovery rate of vanadium ions in the vanadium slag and the purity of the recovered product vanadium pentoxide can be effectively increased, meanwhile, the extraction solvent in the recovery process can be recycled, and the recovery cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium liquid extraction, and in particular relates to a method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag. Background Art

[0002] Vanadium pentoxide (V2O5) is an important chemical raw material with excellent physical and chemical properties. High-purity V2O5 is the basic raw material for the preparation of high-purity metallic vanadium and high-purity vanadium compounds. In recent years, with the continuous advancement of science and technology, new energy such as photovoltaics, wind power and microgrids, all-vanadium liquid flow batteries for large-scale energy storage, lithium vanadate high-performance lithium-ion batteries and advanced vanadium alloys have increasingly higher requirements for the purity of vanadium products, and thus the demand for high-purity V2O5 is increasing.

[0003] In the prior art, vanadium ions in vanadium slag are generally recovered by converting the vanadium slag into vanadium liquid, and then extracting the vanadium liquid to recover vanadium pentoxide. The entire operation process is complicated and costly. In addition, when the vanadium liquid is extracted in the prior art, impurity ions such as Mn, Mg, Fe, and Ca in the vanadium slag will also enter the organic phase along with the vanadium ions, resulting in low purity of the recovered vanadium pentoxide.

[0004] For example, the prior art method for extracting vanadium pentoxide can use a multi-unit continuous ion exchange method to treat the vanadic acid leaching solution. Although this method can save the amount of resin, improve the resin utilization rate, and increase the metal adsorption per unit volume of resin by 50%, the recovery rate of vanadium extracted by the above method is only 90%, and the ion exchange resin is very easy to be poisoned and fail during use, which will also affect the normal extraction operation. Summary of the invention

[0005] In order to solve the problem of low purity of vanadium pentoxide recovered by vanadium liquid extraction technology in the prior art, the present invention provides a method for preparing vanadium pentoxide by separating and extracting vanadium ions in vanadium slag.

[0006] The present invention is implemented by the following technical scheme: a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, comprising the following steps:

[0007] S1, subjecting vanadium slag to roasting and leaching processes in sequence to obtain a first solution, wherein the vanadium ions in the first solution are pentavalent vanadium ions;

[0008] S2, adding a reducing agent to the first solution to obtain a second solution, wherein the vanadium ions in the second solution are tetravalent vanadium ions;

[0009] S3, adding a complexing agent to the second solution for complexing to obtain a third solution, wherein the molar ratio of the complexing agent to the impurity ions in the second solution is n1:n2>1.2, wherein n1 is the amount of the complexing agent, and n2 is the total amount of the impurity ions in the second solution, and the impurity ions are Mn, Mg, Fe, and Ca; and the pH during the complexing process is 3.0-6.0;

[0010] S4, adding an extraction solvent to the third solution for extraction to obtain an organic phase and an aqueous phase; wherein the tetravalent vanadium ions in the third solution are extracted by the extraction solvent and are located in the organic phase; and the volume ratio of the extraction solvent to the third solution is 0.5:1 to 2:1;

[0011] S5, washing the organic phase with a detergent, and stripping the washed organic phase with a stripping agent, obtaining a stripping solution and a blank organic phase after stripping, wherein the tetravalent vanadium ions in the washed organic phase enter the stripping solution, and the blank organic phase is circulated to the step S4 as an extraction solvent for utilization; the volume ratio of the stripping agent to the washed organic phase is 0.2:1 to 3:1;

[0012] S6, adding a precipitant to the stripping solution, wherein the precipitant is used to precipitate the tetravalent vanadium ions in the stripping solution to obtain a solution containing a precipitate; the molar ratio of the added precipitant to the tetravalent vanadium ions in the stripping solution is n3:n4=1.5, wherein n3 is the amount of the precipitant, and n4 is the amount of the tetravalent vanadium ions in the stripping solution;

[0013] S7, filtering, separating, and drying the solution containing the precipitate in sequence, then introducing air and calcining the solution, and obtaining vanadium pentoxide after the calcination.

[0014] As a further improvement of the present invention, the extraction solvent is a mixture of an extractant, a diluent and a modifier, and the amount of the extractant accounts for 5% to 50% of the volume of the extraction solvent.

[0015] As a further improvement of the present invention, the extractant is dimethylheptyl methyl phosphate.

[0016] As a further improvement of the present invention, the diluent is a mixture of one or more of kerosene, sulfonated kerosene and acetone oxime.

[0017] As a further improvement of the present invention, the modifier is tributyl phosphate.

[0018] As a further improvement of the present invention, during extraction, the extraction temperature is 15° C. to 30° C., the pH is 1.0 to 5.0, and the extraction time is 4 min to 10 min.

[0019] As a further improvement of the present invention, the reducing agent is a mixture of one or more of sodium sulfite, iron powder, sodium sulfide, and ascorbic acid; the concentration of the reducing agent is 10g / L to 100g / L, the reduction time is 1min to 20min, and the temperature during the reduction process is 15°C to 30°C.

[0020] As a further improvement of the present invention, the roasting process adopts one of calcification roasting, sodium roasting, salt-free roasting, and calcium-magnesium composite roasting.

[0021] As a further improvement of the present invention, the complexing agent is a mixture of one or more of ethylenediaminetetraacetic acid, dimercaptopropanol, sodium dimercaptopropane sulfonate, and triethanolamine.

[0022] As a further improvement of the present invention, the complexing time is 5 min to 15 min, and the complexing temperature is 20° C. to 35° C.

[0023] As a further improvement of the present invention, the detergent is one of 0.1mol / L to 1mol / L sulfuric acid, deionized water or 0.1% to 0.5% hydrogen peroxide; the washing time of the detergent is 2min to 8min, and the washing temperature is 15°C to 30°C.

[0024] As a further improvement of the present invention, the stripping agent is a mixture of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, oxalic acid, ammonium carbonate, ammonium chloride, and ammonium nitrate; the concentration of the stripping agent is 0.5 mol / L to 5 mol / L, the stripping time is 5 min to 10 min, and the stripping temperature is 15° C. to 30° C.

[0025] As a further improvement of the present invention, during the calcination process, the calcination temperature is 450° C. to 600° C., and the calcination time is 1.5 h to 3.5 h.

[0026] As a further improvement of the present invention, the complexation rate of the impurity ions in the third solution is greater than 96%, and the complexation rate of the vanadium ions is less than 1%.

[0027] The technical solution provided by the present invention has the following beneficial effects:

[0028] (1) The method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide of the present invention first adopts a complexing agent within a suitable pH range, and then selects dimethylheptyl methyl phosphate as an extractant. Under the cooperation of the two, impurity ions such as Mn, Mg, Fe, and Ca in the second solution will not be extracted into the organic phase, thereby changing the traditional vanadium liquid extraction technology and greatly improving the purity of the subsequently recovered vanadium, thereby solving the problem of low purity of vanadium pentoxide recovered by the vanadium liquid extraction technology in the prior art.

[0029] Therefore, the key point of the present invention is to use P350 extractant, which has a higher extraction effect. At the same time, it cooperates with EDTA and other complexing agents to complex the Mn, Mg, Ca, and Fe impurity ions in the solution, so that the impurity ions will not be extracted into the organic phase synchronously. Therefore, the amount of the extractant can be increased to improve the extraction rate. At the same time, the complexing agent can inhibit the co-extraction of impurity ions, so the purity of the recovered vanadium pentoxide can be improved.

[0030] (2) The complexing agent of the present invention can have a strong complexing effect on the impurity ions in the second solution within a suitable pH range, so that the impurity ions in the second solution will not be extracted into the organic phase, thereby improving the purity of the vanadium obtained after recovery.

[0031] (3) The present invention uses dimethylheptyl methyl phosphate as an extractant, which has high selectivity and good extraction capacity, so that more than 99% of the vanadium ions in the second solution can be extracted and recovered, thereby improving the recovery rate of vanadium ions in vanadium slag, so that the purity of the final vanadium pentoxide is high. In addition, the present invention extracts vanadium ions in the organic phase into the stripping solution through stripping, so that the extraction solvent in the separation and extraction process can be reused, thereby reducing the cost of the separation and extraction process.

[0032] (4) In the present invention, the complexing agent is added in excess, which can complex the impurity ions in the second solution to the greatest extent, and then cooperate with the extractant in the subsequent extraction process to separate the impurity ions from the vanadium ions, so as to improve the purity of the vanadium ions after separation and extraction, and finally prepare high-purity vanadium pentoxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention provides a flow chart of a method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0035] In the description of the present invention, it should be noted that for directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention. The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. The terms "including" and "having" in the specification and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] Example 1

[0037] Please refer to Figure 1 A method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide comprises the following steps:

[0038] S1, subjecting the vanadium slag to roasting and leaching processes in sequence to obtain a first solution, wherein the vanadium ions in the first solution are pentavalent vanadium ions.

[0039] S2, adding a reducing agent to the first solution to obtain a second solution, wherein the vanadium ions in the second solution are tetravalent vanadium ions.

[0040] S3, adding a complexing agent to the second solution for complexing reaction, the molar ratio of the complexing agent to the impurity ions in the second solution is n1:n2>1.2, wherein n1 is the amount of the complexing agent, and n2 is the total amount of the impurity ions in the second solution, and the impurity ions are Mn, Mg, Fe, and Ca; the added complexing agent is used to complex the impurity ions in the second solution to obtain a third solution.

[0041] S4, adding an extraction solvent to the third solution for extraction to obtain an organic phase and an aqueous phase; wherein the tetravalent vanadium ions in the third solution are extracted by the extraction solvent and are located in the organic phase; and the volume ratio of the extraction solvent to the third solution is 0.5:1 to 2:1.

[0042] S5, washing the organic phase with a detergent, and stripping the washed organic phase with a stripping agent, obtaining a stripping solution and a blank organic phase after stripping, wherein the tetravalent vanadium ions in the washed organic phase enter the stripping solution, and the blank organic phase is recycled to step S4 as an extraction solvent for utilization; the volume ratio of the stripping agent to the washed organic phase is 0.2:1 to 3:1.

[0043] S6, adding a precipitant to the stripping solution, the precipitant is used to precipitate the tetravalent vanadium ions in the stripping solution to obtain a solution containing a precipitate; the molar ratio of the added precipitant to the tetravalent vanadium ions in the stripping solution is n3:n4=1.5, wherein n3 is the amount of the precipitant, and n4 is the amount of the tetravalent vanadium ions in the stripping solution.

[0044] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air and calcining the solution. After the calcination is completed, vanadium pentoxide is obtained.

[0045] The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag provided by the invention can recover more than 99% of vanadium in the vanadium slag, and the purity of the obtained product vanadium pentoxide is about 99.9%.

[0046] Among them, in step S1, the roasting process can be carried out by calcium roasting, sodium roasting, salt-free roasting, calcium-magnesium composite roasting, etc. The leaching process can be acid leaching or water leaching, and the leaching agent can be sulfuric acid or deionized water.

[0047] During the roasting-leaching process, some solid matter remains undissolved and can be removed as tailings by filtering.

[0048] In step S2, the purpose of adding a reducing agent to the first solution is to reduce the pentavalent vanadium ions in the first solution to tetravalent vanadium ions. The reason for operating this step is that the extraction solvent in the present invention can only extract tetravalent vanadium ions, so before extraction, the pentavalent vanadium ions in the first solution need to be reduced to tetravalent vanadium ions to prepare for the subsequent extraction process.

[0049] Wherein, in the present embodiment, it is judged whether the pentavalent vanadium ions in the first solution are all converted into tetravalent vanadium ions and chemical titration can be used for judgment. In the judgment process, we select N-phenylated anthranilic acid as an indicator, which will be combined with the pentavalent vanadium ions in the solution and show red, and will not be combined with tetravalent vanadium ions. Therefore, in the actual judgment process, it is only necessary to observe whether the second solution changes color, if the second solution does not change color, it means that the pentavalent vanadium ions are all converted into tetravalent vanadium ions under the effect of the reducing agent.

[0050] It is understood that the reducing agent can be a mixture of one or more of sodium sulfite, iron powder, sodium sulfide, and ascorbic acid. The amount of the reducing agent can be controlled within the range of 10 g / L to 100 g / L, the temperature during the reaction of the reducing agent is 15° C. to 30° C., and the reduction time is 1 min to 20 min.

[0051] In step S3, the complexing agent is a metal impurity complexing agent, which can be a mixture of one or more of ethylenediaminetetraacetic acid, dimercaptopropanol, sodium dimercaptopropane sulfonate, and triethanolamine. The purpose of selecting the above complexing agents is that these complexing agents can achieve effective complexing of impurity ions in the second solution without complexing vanadium ions, so that the impurity ions are separated from the vanadium ions in the subsequent extraction process, thereby improving the purity of the vanadium ions after extraction.

[0052] The use of a complexing agent in step S3 can realize complexing of the impurity ions in the second solution, so that the impurity ions in the second solution will not be extracted into the organic phase along with the vanadium ions during the extraction process in step S4, thereby making the purity of the vanadium ions in the organic phase obtained after the extraction in step S4 higher, thereby improving the purity of the recovered vanadium pentoxide.

[0053] During the complexation process, the complexing agent needs to be added in excess. The purpose of adding the excess amount is to complex the impurity ions in the second solution to the greatest extent, thereby cooperating with the subsequent extraction operation to separate the impurity ions from the vanadium ions, so as to improve the purity of the vanadium ions after separation.

[0054] It is understandable that before the experiment is carried out, the total amount of impurity ions in the second solution (i.e., the total amount of impurity ions) can be measured by an inductively coupled plasma mass spectrometer (i.e., ICP), and then the amount required to be added in theory can be calculated based on the complexation reaction equation of the selected complexing agent and the impurity ions. Then, when the amount added is actually greater than the amount required to be added in theory, it can be proved that the amount of complexing agent added is excessive. In this embodiment, the molar ratio of the complexing agent to the impurity ions in the second solution can be calculated, i.e., n1:n2>1.2, and the amount of complexing agent added is excessive. Wherein n1 is the amount of the complexing agent, and n2 is the total amount of the impurity ions in the second solution. During the complexation process, the complexation temperature is 20°C to 35°C, the complexation time is 5min to 15min, and the pH is 3.0 to 6.0.

[0055] Wherein, the extraction solvent is mixed with an extractant, a diluent and a modifier. The extractant may be dimethylheptyl methyl phosphate. The extractant is an environmentally friendly extractant. The selection of the extractant can avoid problems such as personnel poisoning due to improper operation during the treatment of vanadium ions in vanadium slag. The diluent is a mixture of one or more of kerosene, sulfonated kerosene, and acetone oxime. The modifier is tributyl phosphate. Emulsification occurs during the extraction process, and the emulsification phenomenon easily leads to difficulty in phase separation between the organic phase and the aqueous phase, causing the two phases to be entrained with each other, resulting in poor separation effect, and a long separation time of the organic phase and the aqueous phase. Therefore, a modifier is added to the extraction solvent, which can effectively prevent the emulsification phenomenon during the extraction process and reduce the separation time of the organic phase and the aqueous phase, thereby improving the extraction efficiency. The purpose of adding a diluent in the present invention is that the extractants selected in this embodiment are all relatively sticky. If a diluent is not added, the extraction solvent and the third solution cannot be evenly mixed, resulting in the extraction solvent being unable to effectively extract the vanadium ions in the third solution, thereby reducing the extraction rate of the extraction solvent.

[0056] Among them, the chemical formula of dimethylheptyl methyl phosphate is as follows:

[0057]

[0058] The extraction rate of the extraction solvent in this embodiment for vanadium ions is higher than 95%, and the extraction rates for various impurity ions are all less than 5%.

[0059] Among them, the extraction rate can be obtained by chemical titration measurement, as follows: before extraction, the concentration of vanadium ions in the third solution is titrated, and after extraction, the concentration of vanadium ions in the aqueous phase is titrated again, and then by calculating the difference between the two, it is possible to calculate how much vanadium ions are extracted into the organic phase, and then the extraction rate can be calculated.

[0060] During extraction, the extraction temperature is 15°C to 30°C, the pH is 1.0 to 5.0, and the extraction time is 4 min to 10 min.

[0061] In step S4, the extraction solvent and the third solution can be subjected to three-stage extraction, which means that the third solution is mixed with the extraction solvent and subjected to three extractions. By selecting the three-stage extraction, the vanadium ions in the third solution can be extracted to the greatest extent with the least number of extractions.

[0062] During the washing process, the volume ratio of the organic phase to the detergent is controlled within the range of 0.5:1 to 1:0.2. The purpose of setting this range is to effectively wash and remove the trace impurity ions remaining in the organic phase while reducing the amount of detergent used, thereby controlling the cost in the recovery process. It is understandable that in chemical experiments, even if we use complexing agents to inhibit the impurity ions from entering the organic phase through co-extraction, there will still be a very small number of impurity ions that will be extracted into the organic phase. Therefore, after the extraction is completed, we will wash these impurity ions by washing, so that the purity of the vanadium ions in the washed organic phase is higher. The reason why impurity ions can be removed by washing is that the binding between the impurity ions and the extraction solvent is not as tight as the binding between the vanadium ions and the extraction solvent. Therefore, the impurity ions in the organic phase can be removed by washing.

[0063] Furthermore, the detergent may be one of 0.1 mol / L to 1.0 mol / L sulfuric acid, deionized water, and 0.1% to 0.5% hydrogen peroxide.

[0064] It can be understood that in this embodiment, the impurity ions in the second solution are first complexed to the greatest extent by the complexing agent, thereby obtaining the third solution. The vanadium ions in the third solution are then extracted into the organic phase by the extraction solvent, and then the organic phase is washed by the detergent, which can also remove the impurity ions in the organic phase, thereby achieving better removal of the impurity ions in the organic phase, thereby improving the purity of the recovered vanadium pentoxide.

[0065] Among them, the blank organic phase obtained after back extraction in step S5 can be recycled to step S4. Through this operation, the organic phase can be reused, thereby effectively reducing the cost of the entire vanadium ion recovery process.

[0066] Since the vanadium ions in this scheme need to be precipitated in an aqueous solution to achieve the purpose of recovery, the vanadium ions in the organic phase need to be stripped into a stripping solution by a stripping agent after washing, and then a precipitant is added to the stripping solution to obtain a precipitate, which is then filtered, separated, dried, and calcined with air to obtain vanadium pentoxide.

[0067] The stripping agent can be a mixture of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, oxalic acid, ammonium carbonate, ammonium chloride, and ammonium nitrate. The concentration of the stripping agent is in the range of 0.5 mol / L to 5.0 mol / L, the volume ratio of the organic phase to the stripping agent is controlled between 0.2:1 and 3:1, the stripping time is 5 min to 10 min, and the temperature is 15°C to 30°C.

[0068] It is understood that in step S7, the step of filtering the solution containing the precipitate may include filtering after adding a flocculant or filtering directly, and the filtering step may be performed by a precision filter, a centrifugal filter or a membrane filter. In addition, the filtering process may also be replaced by a static treatment of the solution containing the precipitate, and the static treatment time is ≥ 6 hours.

[0069] It is understood that the precipitant may be an ammonium salt, and in this embodiment, any one of (NH4)2CO3, NH4Cl, ammonium nitrate, and ammonia water may be selected. The molar ratio of the precipitant to the stripping solution may be 1.5. The purpose of selecting this molar ratio is to achieve the precipitation of vanadium ions in the stripping solution while the amount of the precipitant is not too much, thereby reducing the cost of the entire recovery process.

[0070] After the precipitation is completed, the solution containing the precipitate is filtered, separated, and dried to remove moisture. During the calcination process, the calcination temperature is 450° C. to 600° C., and the calcination time is 1.5 h to 3.5 h.

[0071] Example 2

[0072] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0073] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 4.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 2.0.

[0074] S2, adding 70 g / L of reducing agent Na2SO3 to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0075] S3, adding EDTA to the second solution in an amount of n1:n2=1.3, stirring at a pH of 4.0 and a temperature of 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by the complexing agent EDTA to obtain a third solution.

[0076] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 10 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 5 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0077] In this embodiment, the extractant is P350, the diluent is sulfonated kerosene, and the modifier is TBP. P350 accounts for 25% of the total volume of the extraction solvent, sulfonated kerosene accounts for 70% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0078] S5, washing the organic phase obtained in step S4 with deionized water, and the volume ratio of deionized water to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 1. The washed organic phase is then stripped with 2.5 mol / L H2SO4 solution at 30°C for 10 min to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 3 min.

[0079] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0080] S6, add 2.5 mol / L (NH4)2CO3 to the stripping solution, the molar ratio of the added (NH4)2CO3 to the vanadium in the stripping solution is 1.5. Under the action of (NH4)2CO3, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0081] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0082] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0083] In this embodiment, EDTA is ethylenediaminetetraacetic acid, P350 is dimethylheptyl methyl phosphate, and TBP is tributyl phosphate.

[0084] In step S3, n1 is the amount of EDTA, and n2 is the total amount of impurity ions in the second solution.

[0085] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.3%, and the purity of vanadium pentoxide obtained after calcination is 99.9%.

[0086] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0087] Example 3

[0088] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0089] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 3.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 2.0.

[0090] S2, adding 75 g / L of reducing agent sodium sulfide to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0091] S3, add dimercaprol to the second solution, and the amount of dimercaprol added is n1:n2=1.4, and stir for 10 minutes at a pH of 4.0 and a temperature of 25°C, so that the impurity ions in the second solution can be complexed by dimercaprol as a complexing agent to obtain a third solution.

[0092] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 8 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 2 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0093] In this embodiment, the extractant is P350, the diluent is sulfonated kerosene, and the modifier is TBP. P350 accounts for 20% of the total volume of the extraction solvent, sulfonated kerosene accounts for 75% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0094] S5, wash the organic phase obtained in step S4 with a 0.5 mol / L H2SO4 solution, and the volume ratio of the H2SO4 solution to the organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 5 times. The washed organic phase is then stripped with a 2.0 mol / L H2SO4 solution at 25°C for 12 minutes to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the separation time of the stripping solution and the blank organic phase is 5 minutes.

[0095] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0096] S6, adding 3.0 mol / L NH4Cl to the stripping solution, wherein the molar ratio of the added NH4Cl to the vanadium in the stripping solution is 1.5. Under the action of NH4Cl, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0097] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 600° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0098] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0099] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0100] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0101] In step S3, n1 is the amount of dimercaptopropanol, and n2 is the total amount of impurity ions in the second solution.

[0102] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.1%, and the purity of vanadium pentoxide obtained after calcination is 99.6%.

[0103] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0104] Example 4

[0105] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0106] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 3.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 3.0.

[0107] S2, adding 70 g / L of ascorbic acid as a reducing agent to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0108] S3, adding sodium dimercaptopropane sulfonate to the second solution, and the amount of sodium dimercaptopropane sulfonate added is n1:n2=1.2, and stirring at a pH of 4.0 and a temperature of 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by the complexing agent sodium dimercaptopropane sulfonate to obtain a third solution.

[0109] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 30° C. and an extraction time of 12 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 2 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0110] In this embodiment, the extractant is P350, the diluent is No. 260 solvent oil, and the modifier is TBP. P350 accounts for 30% of the total volume of the extraction solvent, No. 260 solvent oil accounts for 65% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent. No. 260 solvent oil is also a kind of sulfonated kerosene.

[0111] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 2 times. The washed organic phase is then stripped with 2.0 mol / L HCl solution at 25°C for 10 min to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the separation time of the stripping solution and the blank organic phase is 5 min.

[0112] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0113] S6, adding 3.0 mol / L ammonium nitrate to the stripping solution, wherein the molar ratio of the added ammonium nitrate to the vanadium in the stripping solution is 1.5. Under the action of the ammonium nitrate, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0114] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0115] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0116] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0117] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0118] In step S3, n1 is the amount of sodium dimercaptopropane sulfonate, and n2 is the total amount of impurity ions in the second solution.

[0119] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.4%, and the purity of vanadium pentoxide obtained after calcination is 99.9%.

[0120] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0121] Example 5

[0122] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0123] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 4.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 3.0.

[0124] S2, adding 70 g / L of reducing agent Na2SO3 to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0125] S3, adding triethanolamine to the second solution, and the amount of triethanolamine added is n1:n2=1.5, and stirring at a pH of 4.0 and a temperature of 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by triethanolamine as a complexing agent to obtain a third solution.

[0126] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 9 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 3 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0127] In this embodiment, the extractant is P350, the diluent is acetone oxime, and the modifier is TBP. P350 accounts for 40% of the total volume of the extraction solvent, acetone oxime accounts for 55% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0128] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 1. The washed organic phase is then stripped with 2.5 mol / L oxalic acid solution at 25°C, the volume ratio of organic phase to oxalic acid solution is 1:2, and the stripping time is 12 minutes to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 4 minutes.

[0129] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0130] S6, adding 2.0 mol / L ammonia water to the stripping solution, wherein the molar ratio of the added ammonia water to the vanadium in the stripping solution is 1.5. Under the action of the ammonia water, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0131] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0132] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0133] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0134] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0135] In step S3, n1 is the amount of triethanolamine, and n2 is the total amount of impurity ions in the second solution.

[0136] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.65%, and the purity of vanadium pentoxide obtained after calcination is 99.9%.

[0137] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0138] Example 6

[0139] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0140] S1, vanadium slag is subjected to sodium roasting, and then deionized water is added to obtain vanadium liquid for leaching, and 5.5 mol / L H2SO4 is added to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 2.0.

[0141] S2, adding 70 g / L of ascorbic acid as a reducing agent to the first solution, and then stirring for 6 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0142] S3, adding EDTA to the second solution, and the amount of EDTA added is n1:n2=1.3, and stirring at pH 4.0 and temperature 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by the complexing agent EDTA to obtain the third solution.

[0143] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 7 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 3 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0144] In this embodiment, the extractant is P350, the diluent is acetone oxime, and the modifier is TBP. P350 accounts for 30% of the total volume of the extraction solvent, acetone oxime accounts for 65% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0145] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 3 times. The washed organic phase is then stripped with 2.5 mol / L oxalic acid solution at 25°C, the volume ratio of organic phase to oxalic acid solution is 1:1, and the stripping time is 10 min to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 6 min.

[0146] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0147] S6, adding 2.5 mol / L ammonia water to the stripping solution, wherein the molar ratio of the added ammonia water to the vanadium in the stripping solution is 1.5. Under the action of the ammonia water, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0148] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 500° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0149] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0150] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0151] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0152] In step S3, n1 is the amount of EDTA, and n2 is the total amount of impurity ions in the second solution.

[0153] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.6%, and the purity of vanadium pentoxide obtained after calcination is 99.9%.

[0154] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0155] Example 7

[0156] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0157] S1, vanadium slag is subjected to calcium-magnesium composite roasting, and sulfuric acid is added to obtain vanadium liquid for leaching, and then 3.5 mol / L H2SO4 is added to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 3.0.

[0158] S2, adding 60 g / L of reducing agent Na2SO3 to the first solution, and then stirring for 4 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0159] S3, adding triethanolamine to the second solution, and the amount of triethanolamine added is n1:n2=1.4, and stirring at pH 5.0 and temperature 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by triethanolamine as a complexing agent to obtain a third solution.

[0160] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 8 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 4 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0161] In this embodiment, the extractant is P350, the diluent is acetone oxime, and the modifier is TBP. P350 accounts for 30% of the total volume of the extraction solvent, acetone oxime accounts for 65% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0162] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 3 times. The washed organic phase is then stripped with 2.5 mol / L HCl solution at 25°C, the volume ratio of organic phase to HCl solution is 1:1, and the stripping time is 9 minutes to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 6 minutes.

[0163] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0164] S6, adding 3.0 mol / L ammonium nitrate to the stripping solution, wherein the molar ratio of the added ammonium nitrate to the vanadium in the stripping solution is 1.5. Under the action of the ammonium nitrate, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0165] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0166] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0167] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0168] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0169] In step S3, n1 is the amount of triethanolamine, and n2 is the total amount of impurity ions in the second solution.

[0170] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.3%, and the purity of vanadium pentoxide obtained after calcination is 99.9%.

[0171] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0172] Comparative Example 1

[0173] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0174] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 4.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 3.0.

[0175] S2, adding 70 g / L of reducing agent Na2SO3 to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0176] S3, adding EDTA to the second solution, and the amount of EDTA added is n1:n2=1.3, and stirring at pH 4.0 and temperature 25°C for 8 minutes, so that the impurity ions in the second solution can be complexed by the complexing agent EDTA to obtain the third solution.

[0177] S4, the third solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 10 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 4 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the third solution can be extracted by the extraction solvent and then located in the organic phase.

[0178] In this embodiment, the extractant is P204, the diluent is sulfonated kerosene, and the modifier is TBP. P204 accounts for 30% of the total volume of the extraction solvent, sulfonated kerosene accounts for 65% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0179] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 2 times. The washed organic phase is then stripped with 3.5 mol / L H2SO4 solution at 25°C, the volume ratio of organic phase to H2SO4 solution is 1:1, and the stripping time is 10 min to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 2 min.

[0180] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0181] S6, add 2.5 mol / L (NH4)2CO3 to the stripping solution, the molar ratio of the added (NH4)2CO3 to the vanadium in the stripping solution is 1.5. Under the action of (NH4)2CO3, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0182] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0183] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0184] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0185] In this embodiment, P204 is dioctyl phosphate and TBP is tributyl phosphate.

[0186] In step S3, n1 is the amount of EDTA, and n2 is the total amount of impurity ions in the second solution.

[0187] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 91.8%, and the purity of vanadium pentoxide obtained after calcination is 87.7%.

[0188] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0189] Comparative Example 2

[0190] This embodiment provides a method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide, which comprises the following steps:

[0191] S1, calcining and roasting the vanadium slag, adding sulfuric acid to obtain vanadium liquid, and then adding 4.5 mol / L H2SO4 to the vanadium liquid to adjust its pH, thereby obtaining a first solution with a pH of 3.0.

[0192] S2, adding 70 g / L of reducing agent Na2SO3 to the first solution, and then stirring for 8 minutes to obtain a second solution mainly containing tetravalent vanadium and divalent iron, and the concentration of vanadium in the second solution is 24 g / L.

[0193] S3, the second solution and the extraction solvent are mixed in a volume ratio of 1:1, and a three-stage extraction is performed at a temperature of 25° C. and an extraction time of 10 minutes to obtain an organic phase and an aqueous phase. The phase separation time of the organic phase and the aqueous phase is 3 minutes. Under the action of the extraction solvent, the tetravalent vanadium ions in the second solution can be extracted by the extraction solvent and then located in the organic phase.

[0194] In this embodiment, the extractant is P350, the diluent is sulfonated kerosene, and the modifier is TBP. P350 accounts for 30% of the total volume of the extraction solvent, sulfonated kerosene accounts for 65% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0195] S5, wash the organic phase obtained in step S4 with 0.5 mol / L H2SO4 solution, and the volume ratio of H2SO4 solution to organic phase is 1:1, the washing temperature is 25°C, and the number of washings is 2 times. The washed organic phase is then stripped with 3.0 mol / L H2SO4 solution at 25°C, the volume ratio of organic phase to H2SO4 solution is 1:2, and the stripping time is 12 minutes to obtain a stripping solution and a blank organic phase. After extraction with a stripping agent, the tetravalent vanadium ions in the organic phase enter the stripping solution, and the phase separation time of the stripping solution and the blank organic phase is 5 minutes.

[0196] The blank organic phase obtained in step S5 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0197] S6, adding 3.0 mol / L ammonia water to the stripping solution, wherein the molar ratio of the added ammonia water to the vanadium in the stripping solution is 1.5. Under the action of the ammonia water, the vanadium ions in the stripping solution are precipitated, and a solution containing precipitates is obtained.

[0198] S7, filtering, separating, and drying the solution containing the precipitate in sequence, and then introducing air to calcine at 550° C. for 2.5 hours. After the calcination, vanadium pentoxide with high purity is obtained.

[0199] In this embodiment, the purpose of using 0.5 mol / L H2SO4 solution to wash the organic phase is that during the phase separation process, some other ions are entrained in the organic phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium ions in the organic phase is higher.

[0200] In this embodiment, the impurity ions are Mn, Mg, Fe, and Ca.

[0201] In this embodiment, P350 is dimethylheptyl methyl phosphate. TBP is tributyl phosphate.

[0202] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 90.1%, and the purity of vanadium pentoxide obtained after calcination is 95.6%.

[0203] It can be understood that the recovery rate is the ratio of the concentration of vanadium ions in the stripping solution to the concentration of vanadium ions in the first solution.

[0204] It can be seen from Examples 2 to 7 that the method for separating and extracting vanadium ions from vanadium slag to prepare vanadium pentoxide in the present invention is simple to operate, and the selected complexing agent can have a strong complexing effect on the impurity ions in the solution within a suitable pH range, so that the impurity ions complexed by the complexing agent will not enter the organic phase with the vanadium ions, and through the mutual cooperation of the complexing agent and the extraction solvent, the purity of the vanadium pentoxide recovered in each embodiment is also 99.9%, thereby achieving the recovery of high-purity vanadium pentoxide.

[0205] It can be seen from the experimental results in Examples 2 to 7 that the recovery rate of vanadium ions in vanadium slag is above 99.1%, and the purity of the recovered vanadium pentoxide is also 99.9%. This proves that the method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag of the present invention can achieve efficient recovery of vanadium ions in vanadium slag.

[0206] In the method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag in comparative example 1, P204 is selected as the extractant, and the recovery rate of vanadium ions in the vanadium slag is 91.8%, and the purity of vanadium pentoxide obtained after calcination is 87.7%. Comparing it with the data of any group in Example 2 and Example 7, it can be seen that the recovery rate in the vanadium slag and the purity of the recovered vanadium pentoxide are both lower than the data of any group in Example 2 to Example 7. It can be seen that the use of P350 as the extractant in the present invention can effectively improve the recovery rate of vanadium ions in the vanadium slag and the purity of the recovered vanadium pentoxide.

[0207] In the method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag in comparative example 2, no complexing agent is added, but P350 is selected as the extractant. The recovery rate of vanadium ions in the vanadium slag obtained by the method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag in comparative example 2 is 90.1%, and the purity of vanadium pentoxide obtained after calcination is 95.6%. Comparing it with the data of any group in Examples 2 to 7, it can be seen that adding a complexing agent in the method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag can effectively improve the recovery rate of vanadium ions in vanadium slag and the purity of the recovered vanadium pentoxide.

[0208] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag, characterized in that: It includes the following steps: S1, subjecting vanadium slag to roasting and leaching processes in sequence to obtain a first solution, wherein the vanadium ions in the first solution are pentavalent vanadium ions; S2, adding a reducing agent to the first solution to obtain a second solution, wherein the vanadium ions in the second solution are tetravalent vanadium ions; S3, adding a complexing agent to the second solution for complexing to obtain a third solution, wherein the molar ratio of the complexing agent to the impurity ions in the second solution is n1:n2>1.2, wherein n1 is the amount of the complexing agent, and n2 is the total amount of the impurity ions in the second solution, and the impurity ions are Mn, Mg, Fe, and Ca; and the pH during the complexing process is 3.0-6.0; S4, adding an extraction solvent to the third solution for extraction to obtain an organic phase and an aqueous phase; wherein the tetravalent vanadium ions in the third solution are extracted by the extraction solvent and are located in the organic phase; and the volume ratio of the extraction solvent to the third solution is 0.5:1 to 2:1; S5, washing the organic phase with a detergent, and stripping the washed organic phase with a stripping agent, obtaining a stripping solution and a blank organic phase after stripping, wherein the tetravalent vanadium ions in the washed organic phase enter the stripping solution, and the blank organic phase is circulated to the step S4 as an extraction solvent for utilization; the volume ratio of the stripping agent to the washed organic phase is 0.2:1 to 3:1; S6, adding a precipitant to the stripping solution, wherein the precipitant is used to precipitate the tetravalent vanadium ions in the stripping solution to obtain a solution containing a precipitate; the molar ratio of the added precipitant to the tetravalent vanadium ions in the stripping solution is n3:n4=1.5, wherein n3 is the amount of the precipitant, and n4 is the amount of the tetravalent vanadium ions in the stripping solution; S7, filtering, separating, and drying the solution containing the precipitate in sequence, then introducing air and calcining the solution, and obtaining vanadium pentoxide after the calcination.

2. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The extraction solvent is mixed with an extractant, a diluent and a modifier, and the amount of the extractant accounts for 5% to 50% of the volume of the extraction solvent.

3. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 2, characterized in that: The extractant is dimethylheptyl methyl phosphate; the diluent is a mixture of one or more of kerosene, sulfonated kerosene and acetone oxime; the modifier is tributyl phosphate; during extraction, the extraction temperature is 15°C to 30°C, the pH is 1.0 to 5.0, and the extraction time is 4min to 10min.

4. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The reducing agent is a mixture of one or more of sodium sulfite, iron powder, sodium sulfide, and ascorbic acid; the concentration of the reducing agent is 10g / L to 100g / L, the reduction time is 1min to 20min, and the temperature during the reduction process is 15°C to 30°C.

5. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The roasting process adopts one of calcification roasting, sodium roasting, salt-free roasting and calcium-magnesium composite roasting.

6. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The complexing agent is a mixture of one or more of ethylenediaminetetraacetic acid, dimercaptopropanol, sodium dimercaptopropane sulfonate and triethanolamine; the complexing time is 5 minutes to 15 minutes, and the complexing temperature is 20° C. to 35° C.

7. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The detergent is one of 0.1mol / L to 1mol / L sulfuric acid, deionized water or 0.1% to 0.5% hydrogen peroxide; the washing time of the detergent is 2min to 8min, and the washing temperature is 15°C to 30°C.

8. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The stripping agent is a mixture of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, oxalic acid, ammonium carbonate, ammonium chloride, and ammonium nitrate; the concentration of the stripping agent is 0.5 mol / L to 5 mol / L, the stripping time is 5 min to 10 min, and the stripping temperature is 15° C. to 30° C.

9. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: During the calcination process, the calcination temperature is 450°C to 600°C, and the calcination time is 1.5h to 3.5h.

10. The method for preparing vanadium pentoxide by separating and extracting vanadium ions from vanadium slag according to claim 1, characterized in that: The complexing rate of the impurity ions in the third solution is greater than 96%, and the complexing rate of the vanadium ions is less than 1%.

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