Method for preparing high-purity vanadium pentoxide through vanadium slag separation

Abstract

The invention discloses a method for preparing high-purity vanadium pentoxide through vanadium slag separation, and relates to the technical field of vanadium liquid extraction. According to the method, impurity ions are extracted into an organic phase by utilizing the selectivity of the extraction agent, and vanadium ions are left in the solution, so that the vanadium ions and the impurity ions are efficiently separated, and the purpose of recovering high-purity vanadium is achieved; in the extraction process, a complexing agent is added into the vanadium liquid, the complexing agent can be combined with vanadium ions in the vanadium liquid, extraction of the vanadium ions is inhibited, extraction of impurity ions can be promoted, the vanadium recovery efficiency and the purity of the recovered vanadium are further improved, meanwhile, compared with the concentration of the vanadium ions in the vanadium liquid, the concentration of the impurity ions is low, and the purity of the recovered vanadium is high. Therefore, compared with a traditional method, the method is more efficient and lower in cost.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium liquid extraction, in particular to a method for preparing high-purity vanadium pentoxide by separating vanadium slag. Background Art

[0002] Vanadium pentoxide (V2O5) is an important inorganic compound with a wide range of industrial applications. It plays an important role in energy, steel smelting, chemical industry, aviation, military industry and other fields. Vanadium is a strategic metal. Due to its active chemical properties, it is mostly combined with other substances in the form of compounds in nature, and its grade is low. If vanadium pentoxide is prepared directly from ore, the cost is high. Therefore, vanadium pentoxide is mostly prepared from iron tailings (vanadium slag) of vanadium-titanium magnetite. The vanadium in the vanadium slag is leached into the solution by roasting and leaching, and then high-purity vanadium oxide is prepared by purification and enrichment.

[0003] At present, the existing enrichment and purification technologies mainly include solvent extraction, ion exchange, chemical precipitation, etc. However, when the ion exchange method recovers vanadium in the solution, the adsorption resin will preferentially adsorb with the impurity ions, resulting in resin poisoning. Secondly, the cost of this method is high, the adsorption capacity is small, and the operation is complicated. At the same time, although the chemical precipitation method is more efficient, it will cause other ions other than vanadium to precipitate simultaneously during the precipitation process, resulting in a lower purity of the recovered vanadium. However, the solvent extraction method has the advantages of simple operation, large one-time processing capacity, high recovery efficiency, low cost, and environmental friendliness, and has always been considered as the preferred way to recover vanadium. At present, the conventional method is to extract vanadium ions from the solution into the organic phase by reduction extraction, and the impurity ions are left in the solution to achieve the purpose of impurity removal, but the purity of the recovered vanadium is low and the recovery efficiency is low.

[0004] Publication No.: CN118221308A proposes a short-process method for preparing vanadium electrolyte directly from stone coal, firstly crushing the stone coal, then alkali leaching, obtaining saturated alkali leaching solution and stone coal powder, then acid leaching the stone coal powder, then removing aluminum and iron in the leaching solution, concentrating the leaching solution to obtain vanadium liquid, and finally using reduction extraction to recover vanadium ions in the vanadium liquid. The results show that the purity of the recovered vanadium is about 98%. However, the patent process is cumbersome, the recovery efficiency is low, and the purity of the recovered vanadium is not high.

[0005] The publication number is: CN118221308A, which proposes a method for the full recycling of vanadium shale vanadium extraction wastewater. First, hydrochloric acid is used to remove calcium from vanadium shale powder to obtain calcium-removed vanadium shale and calcium-removed liquid; concentrated sulfuric acid is added to the calcium-removed vanadium shale for leaching, and after the leaching is complete, the solid and liquid are separated to obtain a leachate and a leach residue; the pH value of the leachate is adjusted with alkali; sodium sulfite is added to the leachate to obtain an extractant, and then the extractant is extracted and separated to obtain ammonium polyvanadate. Although this method can achieve full recycling of vanadium extraction wastewater, there is no secondary waste residue and high-purity by-products can be obtained. However, the operation of this method is relatively complicated, and the purity of the recovered vanadium is only about 98%.

[0006] Publication No.: CN117258353A discloses a method for preparing a vanadium sulfate electrolyte from a waste FCC catalyst, wherein the waste catalyst is first leached with sulfuric acid to obtain a vanadium leaching solution, and then an extractant is used for extraction, back extraction, impurity removal and concentration to obtain an electrolyte. Although the purity of the finally prepared vanadium sulfate electrolyte is greater than 99.5%, the amount of extractant used in the extraction process is relatively large, resulting in high costs.

[0007] Patent CN115852171A proposes a method for separating and extracting vanadium, manganese and titanium from vanadium-titanium magnetite. First, vanadium-titanium magnetite is calcined in an oxidizing atmosphere to obtain clinker; dilute sulfuric acid is added to the clinker, leached at room temperature, and filtered to obtain a leachate and an iron concentrate; then, the leachate is heated and filtered to obtain red vanadium and vanadium precipitation mother liquor; sulfur, sulfuric acid and red vanadium are mixed, calcined at low temperature to obtain vanadium oxysulfate, vanadium oxysulfate is dissolved in an aqueous solution to obtain a vanadium oxysulfate solution, the vanadium oxysulfate solution is extracted to obtain a loaded organic phase and a raffinate, and the loaded organic phase is stripped with sulfuric acid to obtain a stripping solution and an empty organic phase; calcium hydroxide and hydrogen peroxide are added to the raffinate, and filtered to obtain a calcium-manganese slag; the calcium-manganese slag is leached with sulfuric acid, and a reducing agent is added for reduction, and filtered to obtain a manganese sulfate solution and a calcium sulfate slag; the empty organic phase is stripped with hydrogen peroxide and dilute sulfuric acid to obtain a titanium-containing liquid. Although this patent can simultaneously recover three valuable metals in vanadium-titanium magnetite, the recovery efficiency is low, with a V recovery rate of about 96%, a Mn recovery rate of about 73%, and a Ti recovery rate of about 84%.

[0008] Therefore, a new solution to the above problems needs to be proposed. Summary of the invention

[0009] The purpose of the present invention is to provide a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, so as to solve the problem of low purity and recovery efficiency of vanadium pentoxide recovered by vanadium liquid extraction technology in the prior art.

[0010] To achieve the above object, the present invention provides the following technical solution: a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, comprising at least the following steps:

[0011] S1: the vanadium slag is roasted and leached to obtain an acidic vanadium liquid, thereby obtaining a first solution;

[0012] S2: adding a certain amount of vanadium complexing agent to the first solution and stirring sufficiently to obtain a second solution;

[0013] S3: adjusting the pH value of the second solution to obtain a third solution;

[0014] S4: mixing the third solution with an extraction solvent in a certain ratio, performing extraction at a certain temperature and time, and obtaining a fourth solution and an organic phase loaded with impurity ions, i.e., an aqueous phase and an organic phase, after extraction;

[0015] S5: using ammonium salt to precipitate the fourth solution to obtain a precipitate;

[0016] S6: filtering, separating, drying and calcining the precipitate to obtain V2O5;

[0017] S7: using a stripping agent to strip the organic phase loaded with impurity ions in step S4 to obtain a blank organic phase.

[0018] As a further improvement of the present invention, the roasting in S1 includes at least one of calcium roasting, sodium roasting, salt-free roasting and calcium-magnesium composite roasting, or a mixture of two or more thereof;

[0019] The leaching method in S1 includes at least one of acid leaching, alkali leaching and water leaching, or a mixture of two or more thereof.

[0020] As a further improvement of the present invention, the complexing agent in S2 is preferably one of sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, and disodium hydrogen phosphate, or a mixture of two or more thereof.

[0021] As a further improvement of the present invention, in S2, the amount of the complexing agent is preferably 20 g / L to 100 g / L, the stirring time is preferably 1 min to 20 min, the temperature is preferably 15° C. to 40° C., and the stirring speed is preferably 200 r / min to 800 r / min.

[0022] As a further improvement of the present invention, the pH value in S3 is preferably 1.0 to 5.0.

[0023] As a further improvement of the present invention, the ratio of the third solution to the extraction solvent is preferably 1:1, the extraction temperature is preferably 15° C. to 30° C., and the extraction time is preferably 4 min to 10 min.

[0024] As a further improvement of the present invention, the extraction solvent in S4 includes an extractant, a diluent and a modifier;

[0025] The extractant is one of di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), di(2,4,4-trimethylpentyl)phosphonic acid (Cyanex272), or a mixture of two or more thereof;

[0026] The diluent is a mixture of one or more of kerosene, sulfonated kerosene and acetone oxime;

[0027] The modifier is tributyl phosphate (TBP).

[0028] As a further improvement of the present invention, the ammonium salt described in S5 includes at least one of NH4Cl, NH4NO3, (NH4)2SO4, or a mixture of two or more thereof.

[0029] As a further improvement of the present invention, the calcination temperature in S6 is preferably 450° C. to 600° C., and the calcination time is preferably 1.5 h to 3.5 h.

[0030] As a further improvement of the present invention, the stripping agent used in S7 includes at least one or more mixtures of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid;

[0031] The concentration of the stripping agent is preferably 0.5 mol / L to 5 mol / L;

[0032] The stripping time is preferably 5 min to 10 min, and the stripping temperature is optimally 15° C. to 30° C.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention utilizes the selectivity of the extractant to extract the impurity ions into the organic phase, and the vanadium ions remain in the solution, so that the vanadium ions and the impurity ions are efficiently separated, thereby achieving the purpose of recovering high-purity vanadium;

[0035] During the extraction process, a vanadium complexing agent is added to the vanadium liquid. The complexing agent can combine with the vanadium ions in the vanadium liquid to inhibit its extraction, and at the same time can promote the extraction of impurity ions, further improving the efficiency and purity of vanadium recovery. At the same time, compared with the vanadium ion concentration in the vanadium liquid, the concentration of impurity ions is lower. Therefore, the method of this patent is more efficient and less costly than the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings and tables described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 It is a schematic diagram of the process of the present invention;

[0038] Table 1 is a schematic diagram of the inhibitory effect of sodium tripolyphosphate on vanadium added in the present invention;

[0039] Table 2 is a schematic diagram showing the effect of whether sodium tripolyphosphate is added and pH on vanadium extraction in the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings and tables in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] Please refer to Table 1-Table 2, a method for preparing high-purity vanadium pentoxide by separation using vanadium slag. The present invention adopts a method of reversely extracting impurity ions in vanadium solution without reducing pentavalent vanadium solution. This method can efficiently separate vanadium from manganese and calcium. At the same time, the vanadium complexing agent added to the acidic vanadium solution can inhibit the extraction of vanadium ions in one step. The purity of the finally prepared V2O5 can reach about 99.6%.

[0042] Table 1 Effect of sodium tripolyphosphate dosage on vanadium extraction

[0043] Dosage of sodium tripolyphosphate 0g / L 60g / L 140g / L Vanadium concentration of the fourth solution after extraction (g / L) 15.62 22.77 23.16 Extraction rate of vanadium (%) 34.30 4.25 2.60

[0044] Table 2 Effects of solution pH and complexing agent on the extraction of vanadium and impurity ions

[0045]

[0046] The present invention can more efficiently recover vanadium and reduce the cost of the recovery process. For details, refer to the following embodiments and comparative examples:

[0047] Example 1

[0048] This embodiment provides a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, which comprises the following steps:

[0049] S1, after the vanadium slag is calcined and roasted, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0050] S2, adding 60 g / L of sodium tripolyphosphate to the first solution, and then stirring at 30° C. and 400 r / min for 4 min to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L.

[0051] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0052] S4, the third solution is mixed with the extraction solvent 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 calcium and manganese impurity ions in the third solution can be extracted into the organic phase, and the addition of sodium tripolyphosphate will inhibit the extraction of vanadium, so that it is retained in the aqueous phase to the greatest extent (the fourth solution).

[0053] In this embodiment, the extractant is P204, the diluent is sulfonated kerosene, and the modifier is TBP. P204 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.

[0054] S5, adding 2.5 mol / L NH4Cl to the fourth solution, wherein the molar ratio of the added NH4Cl to the vanadium in the fourth solution is 1.5. Under the action of NH4Cl, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0055] S6, 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.

[0056] S7, the organic phase obtained in step S4 is stripped with a 2.0 mol / L H2SO4 solution at 25°C for 12 minutes to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 5 minutes.

[0057] The blank organic phase obtained in step S7 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0058] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.5%, and the purity of vanadium pentoxide obtained after calcination is 99.8%.

[0059] Example 2

[0060] This embodiment provides a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, which comprises the following steps:

[0061] S1, after the vanadium slag is calcined and roasted, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0062] S2, adding 40 g / L of sodium tripolyphosphate and 20 g / L of sodium pyrophosphate to the first solution, and then stirring at 30° C. and 400 r / min for 4 min to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L.

[0063] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0064] S4, the third solution is mixed with the extraction solvent 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 calcium and manganese impurity ions in the third solution can be extracted into the organic phase, and the addition of sodium tripolyphosphate and sodium pyrophosphate will inhibit the extraction of vanadium, so that it is retained in the aqueous phase to the greatest extent (the fourth solution).

[0065] In this embodiment, the extractant is P507, the diluent is sulfonated kerosene, and the modifier is TBP. P507 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.

[0066] S5, add 3.5 mol / L NH4NO3 to the fourth solution, the molar ratio of the added NH4NO3 to the vanadium in the fourth solution is 1.5. Under the action of NH4NO3, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0067] S6, 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.

[0068] S7, the organic phase obtained in step S4 is stripped with 2.5 mol / L H2SO4 solution at 25°C for 10 min to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 3 min.

[0069] The blank organic phase obtained in step S7 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0070] 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 99.7%.

[0071] Example 3

[0072] This embodiment provides a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, which comprises the following steps:

[0073] S1, after the vanadium slag is calcined by magnesium, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0074] S2, adding 50 g / L of sodium tripolyphosphate and 10 g / L of sodium hexametaphosphate to the first solution, and then stirring at 30° C. and 400 r / min for 4 min to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L.

[0075] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0076] S4, the third solution is mixed with the extraction solvent 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 4 minutes. Under the action of the extraction solvent, the calcium and manganese impurity ions in the third solution can be extracted into the organic phase, and the addition of sodium tripolyphosphate and sodium hexametaphosphate will inhibit the extraction of vanadium, so that it is retained in the aqueous phase to the greatest extent (the fourth solution).

[0077] In this embodiment, the extractant is Cyanex272, the diluent is kerosene, and the modifier is TBP. Cyanex272 accounts for 20% of the total volume of the extraction solvent, 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.

[0078] S5, adding 3.5 mol / L NH4Cl to the fourth solution, wherein the molar ratio of the added NH4Cl to the vanadium in the fourth solution is 1.5. Under the action of NH4Cl, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0079] S6, 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.

[0080] S7, the organic phase obtained in step S4 is stripped with 3.0 mol / L oxalic acid solution at 25°C for 12 minutes to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 2 minutes.

[0081] The blank organic phase obtained in step S7 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0082] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.2%, and the purity of vanadium pentoxide obtained after calcination is 99.8%.

[0083] Example 4

[0084] This embodiment provides a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, which comprises the following steps:

[0085] S1, after the vanadium slag is calcined and roasted, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0086] S2, adding 60 g / L of sodium tripolyphosphate to the first solution, and then stirring at 30° C. and 400 r / min for 4 min to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L.

[0087] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0088] S4, the third solution is mixed with the extraction solvent 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 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 calcium and manganese impurity ions in the third solution can be extracted into the organic phase, and the addition of sodium tripolyphosphate will inhibit the extraction of vanadium, so that it is retained in the aqueous phase to the greatest extent (the fourth solution).

[0089] In this embodiment, the extractant is P204, the diluent is sulfonated kerosene, and the modifier is TBP. P204 accounts for 10% of the total volume of the extraction solvent, sulfonated kerosene accounts for 85% of the total volume of the extraction solvent, and TBP accounts for 5% of the total volume of the extraction solvent.

[0090] S5, add 2.5 mol / L (NH4)2SO4 to the fourth solution, the molar ratio of the added (NH4)2SO4 to the vanadium in the fourth solution is 1.5. Under the action of (NH4)2SO4, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0091] S6, 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.

[0092] S7, the organic phase obtained in step S4 is stripped with a 3.5 mol / L hydrochloric acid solution at 25°C for 10 min to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 3 min.

[0093] The blank organic phase obtained in step S7 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0094] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.8%, and the purity of vanadium pentoxide obtained after calcination is 99.6%.

[0095] Example 5

[0096] This embodiment provides a method for preparing high-purity vanadium pentoxide by separation of vanadium slag, which comprises the following steps:

[0097] S1, after the vanadium slag is sodium-treated and roasted, deionized water is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0098] S2, adding 30 g / L of sodium tripolyphosphate and 30 g / L of disodium hydrogen phosphate to the first solution, and then stirring at 30° C. and 400 r / min for 4 min to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L.

[0099] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0100] S4, the third solution is mixed with the extraction solvent 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 calcium and manganese impurity ions in the third solution can be extracted into the organic phase, and the addition of sodium tripolyphosphate and disodium hydrogen phosphate will inhibit the extraction of vanadium, so that it is retained in the aqueous phase to the greatest extent (the fourth solution).

[0101] In this embodiment, the extractant is P507, the diluent is acetone oxime, and the modifier is TBP. P507 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.

[0102] S5, add 2.5 mol / L (NH4)2SO4 to the fourth solution, the molar ratio of the added (NH4)2SO4 to the vanadium in the fourth solution is 1.5. Under the action of (NH4)2SO4, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0103] S6, 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.

[0104] S7, the organic phase obtained in step S4 is stripped with a 3.0 mol / L sulfuric acid solution at 25°C for 14 minutes to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 2 minutes.

[0105] The blank organic phase obtained in step S7 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0106] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 99.9%, and the purity of vanadium pentoxide obtained after calcination is 99.7%.

[0107] Comparative Example 1

[0108] S1, after the vanadium slag is calcined and roasted, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0109] S2, adjusting the pH of the first solution to 3.5 using 2.5 M sulfuric acid to obtain a second solution.

[0110] 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 4 minutes to obtain a third solution. Under the action of the extraction solvent, the calcium and manganese impurity ions in the second solution can be extracted into the organic phase.

[0111] In this embodiment, the extractant is P204, the diluent is sulfonated kerosene, and the modifier is TBP. P204 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.

[0112] S4, adding 2.5 mol / L NH4Cl to the third solution, wherein the molar ratio of the added NH4Cl to the vanadium in the third solution is 1.5. Under the action of NH4Cl, the vanadium ions in the third solution are precipitated, and a solution containing precipitates is obtained.

[0113] S5, 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.

[0114] S6, the organic phase obtained in step S3 is stripped with a 3.5 mol / L sulfuric acid solution at 25°C for 10 min to obtain a Ca-rich and Mn-rich solution and a blank organic phase. After extraction with the stripping agent, the calcium and manganese ions in the organic phase enter the Ca-rich and Mn-rich solution, and the phase separation time is 2 min.

[0115] The blank organic phase obtained in step S6 can be recycled as an extraction solvent, and this operation can effectively reduce the cost of the entire recovery process.

[0116] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 70.1%, and the purity of vanadium pentoxide obtained after calcination is 75.1%.

[0117] Comparative Example 2

[0118] S1, after the vanadium slag is calcined and roasted, sulfuric acid is added for leaching to obtain a first solution, wherein the vanadium in the first solution is mainly pentavalent.

[0119] S2, adding 70 g / L of sodium sulfite to the first solution, and then stirring for 4 minutes to obtain a second solution, wherein the concentration of vanadium in the second solution is 24 g / L, and the vanadium in the second solution is mainly tetravalent vanadium.

[0120] S3, adjusting the pH of the second solution to 3.5 using 2.5 M sulfuric acid to obtain a third solution.

[0121] S4, the third solution and the extraction solvent are mixed at 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.

[0122] In this embodiment, the extractant is P204, the diluent is sulfonated kerosene, and the modifier is TBP. P204 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.

[0123] S5, the organic phase obtained in step S4 is back-extracted with a 3.0 mol / L sulfuric acid solution at 25°C for 12 min to obtain a fourth solution and a blank organic phase.

[0124] S7, add 2.5 mol / L (NH4)2SO4 to the fourth solution, the molar ratio of the added (NH4)2SO4 to the vanadium in the fourth solution is 1.5. Under the action of (NH4)2SO4, the vanadium ions in the fourth solution are precipitated, and a solution containing precipitates is obtained.

[0125] S8, 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.

[0126] In this embodiment, the recovery rate of vanadium ions in the vanadium slag is 89.3%, and the purity of vanadium pentoxide obtained after calcination is 87.7%.

[0127] From Comparative Example 1, it can be seen that if no complexing agent is added to inhibit the extraction of vanadium, a large amount of vanadium will be S3 | is extracted into the organic phase, resulting in a decrease in the recovery rate of vanadium. At the same time, as the extraction rate of vanadium increases, the extraction rate of calcium and manganese impurity ions decreases accordingly. At the same time, the concentration of impurity ions remaining in the fourth solution increases, resulting in a significant decrease in the purity of the recovered vanadium.

[0128] It can be seen from Comparative Example 2 that if the vanadium in the solution is recovered by the traditional reduction extraction method, although the extraction rate of vanadium can reach about 90%, the purity of vanadium is low, less than 90%. It can be seen that the use of the patented method can not only improve the efficiency of vanadium recovery, but also improve the purity of the recovered vanadium.

[0129] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing high-purity vanadium pentoxide by separation of vanadium slag, characterized in that: At least the following steps are included: S1: the vanadium slag is roasted and leached to obtain an acidic vanadium liquid, thereby obtaining a first solution; S2: adding a certain amount of vanadium complexing agent to the first solution and stirring sufficiently to obtain a second solution; S3: adjusting the pH value of the second solution to obtain a third solution; S4: mixing the third solution with an extraction solvent in a certain ratio, performing extraction at a certain temperature and time, and obtaining a fourth solution and an organic phase loaded with impurity ions, i.e., an aqueous phase and an organic phase, after extraction; S5: using ammonium salt to precipitate the fourth solution to obtain a precipitate; S6: filtering, separating, drying and calcining the precipitate to obtain V2O5; S7: using a stripping agent to strip the organic phase loaded with impurity ions in step S4 to obtain a blank organic phase.

2. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: The roasting in S1 includes at least one of calcium roasting, sodium roasting, salt-free roasting and calcium-magnesium composite roasting, or a mixture of two or more thereof; The leaching method in S1 includes at least one of acid leaching, alkali leaching and water leaching, or a mixture of two or more thereof.

3. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: In step S2, the complexing agent is preferably one of sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, and disodium hydrogen phosphate, or a mixture of two or more thereof.

4. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 2, characterized in that: In step S2, the dosage of the complexing agent is preferably 20 g / L to 100 g / L, the stirring time is preferably 1 min to 20 min, the temperature is preferably 15° C. to 40° C., and the speed is preferably 200 r / min to 800 r / min.

5. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: The pH value in S3 is preferably 1.0 to 5.

0.

6. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: The ratio of the third solution to the extraction solvent is preferably 1:1, the extraction temperature is preferably 15° C. to 30° C., and the extraction time is preferably 4 min to 10 min.

7. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 5, characterized in that: The extraction solvent in S4 includes an extractant, a diluent and a modifier; The extractant is one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, and di(2,4,4-trimethylpentyl)phosphonic acid, or a mixture of two or more thereof; The diluent is a mixture of one or more of kerosene, sulfonated kerosene and acetone oxime; The modifier is tributyl phosphate.

8. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 6, characterized in that: The ammonium salt described in S5 includes at least one of NH4Cl, NH4NO3, (NH4)2SO4, or a mixture of two or more thereof.

9. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: The calcination temperature in S6 is preferably 450° C. to 600° C., and the calcination time is preferably 1.5 h to 3.5 h.

10. The method for preparing high-purity vanadium pentoxide by separation of vanadium slag according to claim 1, characterized in that: The stripping agent used in S7 includes at least one or more of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; The concentration of the stripping agent is preferably 0.5 mol / L to 5 mol / L; The stripping time is preferably 5 min to 10 min, and the stripping temperature is optimally 15° C. to 30° C.

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