Method for preparing high-purity vanadium oxide from vanadium slag

Abstract

The invention relates to the technical field of vanadium slag roasting, and discloses a method for preparing high-purity vanadium oxide from vanadium slag, which comprises the following steps: carrying out calcification roasting and acid leaching on the vanadium slag to obtain an acidic vanadium-containing solution; adding an excessive impurity removal agent into the acidic vanadium-containing solution to remove impurity ions in the solution; adding a reducing agent into the acidic vanadium-containing solution to reduce pentavalent vanadium into tetravalent vanadium; extracting the acidic vanadium-containing solution by adopting an extracting solvent to obtain a negative vanadium organic phase; washing the negative vanadium organic phase; carrying out back extraction on the washed negative vanadium organic phase by using a back extraction agent to obtain back extraction raffinate and a blank organic phase, wherein the blank organic phase is recycled as an extraction solvent; and precipitating the reverse extraction raffinate, drying and calcining to obtain vanadium pentoxide. The method is simple in process, low in cost and environmentally friendly, 95% or above of vanadium in the vanadium liquid can be recycled, and the purity of the obtained product vanadium pentoxide is about 99%.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium slag roasting, and in particular to a method for preparing high-purity vanadium oxide from vanadium slag. Background Art

[0002] The vanadium slag roasting-acid leaching process has a great cost advantage in the industry, opening up another way to extract vanadium resources, realizing green vanadium extraction, and has broad prospects for application. However, the acidic vanadium liquid produced by this process contains a large number of cations, such as manganese, calcium, magnesium, iron, titanium, etc. The red vanadium obtained by direct precipitation has a high impurity content. The product varieties processed and manufactured by it are relatively single, and the downstream market expansion scope is relatively limited. It is difficult to purify the acidic vanadium liquid to process and manufacture vanadium products with higher purity, mainly because there are many types of impurity cation elements and high content, which seriously affects the improvement of the purity of the vanadium liquid. At present, most of the industry needs to carry out secondary dissolution and impurity removal, or even repeatedly dissolve and precipitate to remove impurities in it, in order to obtain high-purity vanadium liquid, and then manufacture various downstream high-purity vanadium products, such as high-purity vanadium, vanadium electrolyte, ammonium polyvanadate, etc. The process is long, the cost is high, and the resource utilization rate is not high, which seriously restricts the development and promotion of the "vanadium slag roasting-acid leaching" process.

[0003] Therefore, there is a need in the prior art for improving the method for preparing high-purity vanadium oxide from vanadium slag. Summary of the invention

[0004] In view of this, the purpose of the embodiment of the present invention is to propose a method for preparing high-purity vanadium oxide from vanadium slag. The method has a simple process, low cost, and is environmentally friendly. It can recover more than 95% of vanadium in vanadium liquid, and the purity of the obtained product vanadium pentoxide is about 99%.

[0005] Based on the above purpose, an embodiment of the present invention provides a method for preparing high-purity vanadium oxide from vanadium slag, comprising: S1 calcining and roasting the vanadium slag and acid leaching to obtain an acidic vanadium-containing solution; S2: adding an excess amount of impurity removal agent to the acidic vanadium-containing solution to remove impurity ions in the solution; S3 adding a reducing agent to the acidic vanadium-containing solution to reduce pentavalent vanadium to tetravalent vanadium; S4 extracts the acidic vanadium-containing solution with an extraction solvent to obtain a vanadium-negative organic phase, wherein the extraction solvent comprises: an extractant, a diluent and a modifier, and the extractant is di(2-ethylhexyl)phosphinic acid; S5 washes the vanadium-containing organic phase; S6 uses a stripping agent to strip the washed vanadium-negative organic phase to obtain a stripping raffinate and a blank organic phase, and the blank organic phase is returned to S4 as an extraction solvent for recycling; S7 precipitates the stripping raffinate, which is then dried and calcined to obtain vanadium pentoxide.

[0006] In some embodiments, in S1, the acidic vanadium-containing solution includes: 24.8 g / L vanadium, 9.62 g / L manganese, 1.46 g / L magnesium, 0.04 g / L iron, and 0.11 g / L calcium.

[0007] In some embodiments, in S2, the pH of the acidic vanadium-containing solution is 3.0-5.5, during the impurity removal process, the solution temperature is 25-50°C, the reaction time is 30-90 min, and the amount of impurity remover added is 1-5 times the impurity ion content in the solution.

[0008] In some embodiments, the impurity removing agent is oxalic acid, and the impurity ions include manganese ions, magnesium ions, iron ions, and calcium ions.

[0009] In some embodiments, in S3, the reducing agent is solid sodium sulfite, the amount of sodium sulfite added to the acidic vanadium-containing solution is 50-70 g / L, the reduction temperature is 30-30° C., and the reduction time is 3-10 min.

[0010] In some embodiments, in S4, the amount of the extractant is 5% to 60% of the volume of the negative vanadium organic phase, the volume ratio of the negative vanadium organic phase to the aqueous phase is (0.2:1) to (3:1), the pH of the extraction system is 1.0 to 4.0, the extraction time is 6 to 10 min, and the solution temperature during extraction is 15 to 30°C.

[0011] In some embodiments, in S4, the modifier is tributyl phosphate, and the diluent includes a mixture of any one or more of kerosene, sulfonated kerosene, 260# solvent oil, acetone oxime, methanol, and ethyl acetate.

[0012] In some embodiments, in S5, the volume ratio of the negative vanadium organic phase to the detergent is (1:1) to (1:0.2), the washing time is 5 to 10 min, the washing temperature is 15 to 30°C, and the detergent includes: sulfuric acid, deionized water, and hydrogen peroxide.

[0013] In some embodiments, in S6, the concentration of the stripping agent is 0.5-5.0 mol / L, the volume of the negative vanadium organic phase and the stripping agent is (0.2:1)-(3:1), the stripping time is 5-10 min, and the solution temperature during stripping is 15-30°C.

[0014] In some embodiments, in S7, the calcination temperature is 450-550° C., and the calcination time is 1.5-3.5 h.

[0015] The present invention has at least the following beneficial technical effects: The present invention uses di(2-ethylhexyl)phosphinic acid (P227) as an extractant, which has high selectivity, avoids the co-extraction of impurity ions in the extraction process, and greatly improves the purity of the product vanadium pentoxide. At the same time, the extractant has a high extraction capacity, can extract and recover more than 98% of the vanadium in the solution, and realizes efficient recovery of vanadium. The extractant can be regenerated and reused to reduce costs, and the entire recovery process is simple to operate and is green and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A flow chart of an embodiment of a method for preparing high-purity vanadium oxide from vanadium slag provided by the present invention; Figure 2 The chemical structure diagram of the acidic phosphorus extractant P227 provided by the present invention. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0019] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0020] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0021] like Figure 1 The method for preparing high-purity vanadium oxide from vanadium slag provided by the present invention comprises the following steps: S1 calcining and roasting the vanadium slag and acid leaching to obtain an acidic vanadium-containing solution; S2: adding an excess amount of impurity removal agent to the acidic vanadium-containing solution to remove impurity ions in the solution; S3 adding a reducing agent to the acidic vanadium-containing solution to reduce pentavalent vanadium to tetravalent vanadium; S4 extracts the acidic vanadium-containing solution with an extraction solvent to obtain a vanadium-negative organic phase, wherein the extraction solvent comprises: an extractant, a diluent and a modifier, and the extractant is di(2-ethylhexyl)phosphinic acid; S5 washes the vanadium-containing organic phase; S6 uses a stripping agent to strip the washed vanadium-negative organic phase to obtain a stripping raffinate and a blank organic phase, and the blank organic phase is returned to S4 as an extraction solvent for recycling; S7 precipitates the stripping raffinate, which is then dried and calcined to obtain vanadium pentoxide.

[0022] Furthermore, in S1, the acidic vanadium-containing solution includes: 24.8 g / L vanadium, 9.62 g / L manganese, 1.46 g / L magnesium, 0.04 g / L iron, and 0.11 g / L calcium.

[0023] Further, in S2, the pH of the acidic vanadium-containing solution is 3.0-5.5, the solution temperature is 25-50°C during the impurity removal process, the reaction time is 30-90 min, and the amount of impurity remover added is 1-5 times the content of impurity ions in the solution. In some embodiments, the impurity remover is oxalic acid, and the impurity ions include manganese ions, magnesium ions, iron ions, and calcium ions. After this step of impurity removal, the vanadium loss rate is guaranteed to be <5%, and the precipitation rate of impurity ions (Mn, Mg, Fe, Ca) is >90%.

[0024] Furthermore, in S3, the reducing agent is solid sodium sulfite, the amount of sodium sulfite added to the acidic vanadium-containing solution is 50-70 g / L, the reduction temperature is 30-30°C, and the reduction time is 3-10 min.

[0025] Furthermore, in S4, the amount of the extractant is 5% to 60% of the volume of the negative vanadium organic phase, the volume ratio of the negative vanadium organic phase to the aqueous phase is (0.2:1) to (3:1), the pH of the extraction system is 1.0 to 4.0, the extraction time is 6 to 10 min, and the solution temperature during extraction is 15 to 30°C.

[0026] Further, in S4, the extractant is di(2-ethylhexyl)phosphinic acid (P227), the modifier is tributyl phosphate, and the diluent includes a mixture of any one or more of kerosene, sulfonated kerosene, 260# solvent oil, acetone oxime, methanol, and ethyl acetate. As a preferred technical solution, the acidic phosphorus extractant P227 is as follows: Figure 2As shown, the extraction mechanism is that the OH bond in the POH bond breaks during the extraction process, PO combines with the vanadium oxycations in the solution, and the vanadium oxycations in the solution are loaded into the organic phase.

[0027] Furthermore, in S5, the volume ratio of the negative vanadium organic phase to the detergent is (1:1)~(1:0.2), the washing time is 5~10 min, the washing temperature is 15~30°C, and the detergent includes: sulfuric acid, deionized water, and hydrogen peroxide.

[0028] Furthermore, in S6, the concentration of the stripping agent is 0.5~5.0 mol / L, the volume of the negative vanadium organic phase and the stripping agent is (0.2:1)~(3:1), the stripping time is 5~10 min, and the solution temperature during stripping is 15~30°C.

[0029] Furthermore, in S7, a standing step and / or a filtering step may be performed before precipitation, the filtering step includes filtering after adding a flocculant or filtering directly, the filtering step uses a precision filter, a centrifugal filter or a membrane filter, and the standing time of the standing step is ≥ 6 hours. In some embodiments, during calcination, the calcination temperature is 450-550° C. and the calcination time is 1.5-3.5 hours.

[0030] The term "TBP" in the present invention refers to tributyl phosphate; the term "P227" in the present invention refers to di(2-ethylhexyl)phosphinic acid; the term "ratio" in the present invention refers to the volume ratio of the oil phase (organic phase) to the aqueous phase (inorganic phase); in the present invention, the three-stage extraction is to mix the acidic vanadium liquid with the extraction solvent and perform three extractions, the four-stage extraction is to perform four extractions, and so on.

[0031] The present invention is further explained below in conjunction with specific embodiments and comparative examples.

[0032] Example 1 The extraction solvent in this embodiment is composed of extraction agent P227, diluent sulfonated kerosene and modifier TBP, wherein the volume percentages of extraction agent P227, diluent sulfonated kerosene and modifier TBP account for 10%, 5% and 85% of the volume percentage of the total extraction agent, respectively.

[0033] The method in this embodiment includes the following steps: (1) The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0034] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase), wherein the volume ratio of the oil phase to the water phase is 1:1; The extraction solvent is a mixture of P227 (extractant), sulfonated kerosene (diluent) and TBP (modifier); wherein P227 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; wherein the extraction temperature is 25°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 10 minutes, and the phase separation time is 5 minutes; The loaded organic phase (oil phase) obtained above was washed with deionized water, the volume ratio of the washing liquid to the loaded organic phase was 1:1, the washing temperature was 25°C, and the washing was performed once; (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with H2SO4 solution to obtain stripping raffinate and blank organic phase; the stripping agent used was H2SO4 solution with a concentration of 2.5 mol / L, the stripping temperature was 30°C, the volume ratio of the loaded organic phase (oil phase) to the H2SO4 solution during stripping was 1:1, the stripping time was 10 min, and the phase separation time was 3 min; The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding a precipitant (NH4)2CO3 to the stripping raffinate, wherein the concentration of the precipitant is 2.5 mol / L and the amount added is such that the molar ratio of (NH4)2CO3 to vanadium in the stripping raffinate is 1.5, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550°C for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained. In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 97.5%, and the purity of vanadium pentoxide obtained after calcination is 99.1%.

[0035] Example 2 In this embodiment, the extraction solvent is composed of extraction agent P227, diluent sulfonated kerosene and modifier TBP, wherein the volume percentages of P227, diluent sulfonated kerosene and modifier TBP account for 20%, 75% and 5% of the volume percentage of the total extraction agent, respectively.

[0036] Sulfonated kerosene is obtained by sulfonating kerosene with concentrated sulfuric acid.

[0037] (1) The method of this embodiment includes the following steps: The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0038] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase); wherein the volume ratio of the oil phase to the water phase is 1:1; The extraction solvent is a mixture of P227 (extractant), sulfonated kerosene (diluent) and TBP (modifier); wherein P227 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 solution; wherein the extraction temperature is 25°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 8 min, and the phase separation time is 3 min; The loaded organic phase (oil phase) obtained above was washed with 0.5 mol / L H2SO4 solution, the volume ratio of washing liquid to loaded organic phase (oil phase) was 1:1, the washing temperature was 25°C, and washing was performed twice; (the purpose of using H2SO4 solution is that during the phase separation process, some other ions are entrained in the oil phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium recovered from the oil phase is high).

[0039] (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with H2SO4 solution to obtain stripping raffinate and blank organic phase; the stripping agent used was H2SO4 solution with a concentration of 2.0 mol / L, the stripping temperature was 25°C, the volume ratio of the oil phase to the H2SO4 solution during stripping was 1:1, the stripping time was 12 min, and the phase separation time was 4 min; The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding a precipitant NH4Cl to the stripping raffinate, wherein the concentration of the precipitant is 3.0 mol / L and the amount added is such that the molar ratio of NH4Cl to vanadium in the stripping raffinate is 1.5, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550°C for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained. In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 99.2%, and the purity of vanadium pentoxide obtained after calcination is 99.5%.

[0040] Example 3 In this embodiment, the extraction solvent is composed of extraction agent P227, diluent 260# solvent oil and modifier TBP, wherein the volume percentages of extraction agent P227, diluent 260# solvent oil and modifier TBP account for 30%, 65% and 5% of the total volume percentage of the extraction agent, respectively.

[0041] The method of this embodiment includes the following steps: (1) The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0042] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase), wherein the volume ratio of the oil phase to the water phase is 1:1; The extraction solvent is a mixture of P227 (extractant), 260# solvent oil (diluent) and TBP (modifier); wherein 2,6-dihydroxyanthraquinone accounts for 30% of the total volume of the extraction solvent, the diluent 260# solvent oil accounts for 65% of the total volume of the extraction solvent; TBP (modifier) ​​accounts for 5% of the total volume of the extraction solvent; wherein the extraction temperature is 30°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 12 min, and the phase separation time is 2 min; The loaded organic phase (oil phase) obtained above was washed with 0.5 mol / L H2SO4 solution, the volume ratio of washing liquid to loaded organic phase (oil phase) was 1:1, and the washing temperature was 25°C, and washing was performed twice. (During the phase separation process, some other ions were entrained in the oil phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium recovered from the oil phase is high).

[0043] (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with HCl solution to obtain stripping raffinate and blank organic phase; the stripping agent used was HCl solution with a concentration of 2.0 mol / L, the stripping temperature was 25°C, the volume ratio of the loaded organic phase (oil phase) to the HCl solution during stripping was 1:1, the stripping time was 8 min, and the phase separation time was 3 min; The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding ammonium nitrate as a precipitant to the stripping raffinate, wherein the concentration of the precipitant is 3.0 mol / L and the amount added is such that the molar ratio of ammonium nitrate to vanadium in the stripping raffinate is 1.5, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550° C. for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained; In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 99.5%, and the purity of vanadium pentoxide obtained after calcination is 99.8%.

[0044] Example 4 In this embodiment, the extraction solvent is composed of extraction agent P227, diluent acetone oxime and modifier TBP, wherein the volume percentages of extraction agent P227, diluent acetone oxime and modifier TBP account for 40%, 55% and 5% of the volume percentage of the total extraction agent, respectively.

[0045] The method in this embodiment includes the following steps: (1) The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0046] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase), wherein the volume ratio of the oil phase to the water phase is 1:1; The extraction solvent is a mixture of extractant P227 (extractant), acetone oxime (diluent) and TBP (modifier); wherein P227 accounts for 40% of the total volume of the extraction solvent, acetone oxime and methanol account for 55% of the total volume of the extraction solvent; TBP accounts for 5% of the total volume of the extraction solvent; wherein the extraction temperature is 25°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 8 min, and the phase separation time is 2 min; The loaded organic phase (oil phase) obtained above was washed with 0.5 mol / L H2SO4 solution, the volume ratio of the washing liquid to the loaded organic phase (oil phase) was 1:1, the washing temperature was 25°C, and the washing was performed once; (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with oxalic acid solution to obtain stripping raffinate and blank organic phase. The concentration of oxalic acid solution used as stripping agent was 2.5 mol / L, the stripping temperature was 25°C, the volume ratio of oil phase to oxalic acid solution was 1:2 in each stripping stage, the stripping time was 10 min, and the phase separation time was 3 min. The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding ammonia water as a precipitant to the stripping raffinate, wherein the concentration of the precipitant is 2.0 mol / L and the amount added is such that the molar ratio of ammonia water to vanadium in the stripping raffinate is 1.5, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550° C. for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained; In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 99.8%, and the purity of vanadium pentoxide obtained after calcination is 98.9%.

[0047] Comparative Example 1 The extraction solvent of this embodiment is composed of extraction agent P204, diluent sulfonated kerosene and modifier TBP, wherein the volume percentages of extraction agent P204, diluent sulfonated kerosene and modifier TBP are 30%, 5% and 65% respectively.

[0048] The method in this embodiment includes the following steps: (1) The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0049] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase), wherein the volume ratio of the extraction solvent oil phase to the water phase is 1:1; The extraction solvent is a mixture of P204 (extractant), sulfonated kerosene (diluent) and TBP (modifier); wherein P204 accounts for 30% of the total volume of the extraction solvent, 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; wherein the extraction temperature is 25°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 10 minutes, and the phase separation time is 4 minutes; The loaded organic phase (oil phase) obtained above was washed with 0.5 mol / L H2SO4 solution, the volume ratio of washing liquid to loaded organic phase (oil phase) was 1:1, the washing temperature was 25°C, and washing was performed twice; (during the phase separation process, some other ions were entrained in the oil phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium recovered from the oil phase is high).

[0050] (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with H2SO4 solution to obtain stripping raffinate and blank organic phase; the stripping agent used was H2SO4 solution with a concentration of 3.5 mol / L, the stripping temperature was 30°C, the volume ratio of the loaded organic phase (oil phase) to the H2SO4 solution during stripping was 1:1, the stripping time was 10 min, and the phase separation time was 2 min; The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding a precipitant (NH4)2CO3 to the stripping raffinate, wherein the concentration of the precipitant is 2.5 mol / L and the amount added is such that the molar ratio of (NH4)2CO3 to vanadium in the stripping raffinate is 1.5, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550°C for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained. In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 91.8%, and the purity of vanadium pentoxide obtained after calcination is 87.7%.

[0051] Comparative Example 2 In this embodiment, the extraction solvent consists of extraction agent P507, diluent sulfonated kerosene and modifier TBP, wherein the volume percentages of extraction agent P507, diluent sulfonated kerosene and modifier TBP account for 30%, 65% and 5% of the total volume percentage of the extraction agent, respectively.

[0052] The method in this embodiment includes the following steps: The vanadium slag is subjected to calcination roasting and acid leaching to obtain acidic vanadium liquid, which specifically includes: Preparation of acidic vanadium liquid: After the vanadium slag is roasted, 4.0 mol / L H2SO4 is added to form a first solution, and the pH of the first solution is adjusted to 3.0; An excess amount of oxalic acid was added to the first solution, and the mixture was fully reacted at 40° C. for 40 min, and then filtered to obtain a second solution.

[0053] Add 70 g / L of reducing agent Na2SO3 to the second solution, and then stir for 5 minutes to obtain a solution mainly containing tetravalent vanadium and divalent iron, that is, acidic vanadium solution; the acidic vanadium solution contains 24 g / L of vanadium; (2) Extracting the acidic vanadium liquid to obtain an oil phase and an aqueous phase, specifically comprising: The acidic vanadium liquid is mixed with an extraction solvent and subjected to three-stage extraction to obtain a loaded organic phase (oil phase) and a raffinate (water phase), wherein the volume ratio of the extraction solvent oil phase to the water phase is 1:1; The extraction solvent is a mixture of P507 (extractant), sulfonated kerosene (diluent) and TBP (modifier); wherein P507 accounts for 30% of the total volume of the extraction solvent, sulfonated kerosene (diluent) accounts for 65% of the total volume of the extraction solvent; TBP (modifier) ​​accounts for 5% of the total volume of the extraction solvent; wherein the extraction temperature is 25°C, the volume ratio of the extraction solvent to the acidic vanadium solution is 1:1, the extraction time is 10 min, and the phase separation time is 3 min; The loaded organic phase (oil phase) obtained above was washed with 0.5 mol / L H2SO4 solution, the volume ratio of washing liquid to loaded organic phase (oil phase) was 1:1, the washing temperature was 25°C, and washing was performed twice; (during the phase separation process, some other ions were entrained in the oil phase. Washing with 0.5 mol / L H2SO4 solution can ensure that the purity of vanadium recovered from the oil phase is high).

[0054] (3) Selecting a stripping agent to strip the oil phase, specifically including: The washed loaded organic phase (oil phase) was stripped with H2SO4 solution to obtain stripping raffinate and blank organic phase. The stripping agent used was oxalic acid solution with a concentration of 3.0 mol / L. The stripping temperature was 25°C. During stripping, the volume ratio of the loaded organic phase (oil phase) to the oxalic acid solution was 1:2. The stripping time was 12 min and the phase separation time was 5 min. The blank organic phase obtained by the back extraction is recycled as an extraction solvent; (4) adding ammonia water as a precipitant to the stripping raffinate, wherein the concentration of the precipitant is 3.0 mol / L and the amount added is 1.5 based on the molar ratio of ammonia water to vanadium in the stripping raffinate, stirring evenly and then allowing to settle. The precipitated solid phase is separated by filtration and then dried to remove moisture, and then oxygen is introduced and calcined at 550° C. for 2.5 h. After the calcination, vanadium pentoxide with a high purity can be obtained; In this embodiment, the recovery rate of vanadium in the acidic vanadium solution is 90.1%, and the purity of vanadium pentoxide obtained after calcination is 95.6%.

[0055] By comparing the examples and the comparative examples, it is found that the recovery rate of vanadium in the acidic vanadium solution in Examples 1 to 4 is more than 97%, and the purity of the vanadium pentoxide obtained after calcination is more than 99%, while the recovery rate of vanadium in the acidic vanadium solution in the comparative example is less than 92%, and the purity of the vanadium pentoxide obtained after calcination is less than 95%, indicating that a suitable extractant can increase the recovery rate of vanadium and increase the purity of the vanadium pentoxide obtained after calcination of the stripping raffinate.

[0056] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0057] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0058] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0059] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing high-purity vanadium oxide from vanadium slag, characterized in that: include: S1 calcining and roasting the vanadium slag and acid leaching to obtain an acidic vanadium-containing solution; S2 adding an excess amount of an impurity removal agent to the acidic vanadium-containing solution to remove impurity ions in the solution; S3: adding a reducing agent to the acidic vanadium-containing solution to reduce pentavalent vanadium to tetravalent vanadium; S4 extracting the acidic vanadium-containing solution with an extraction solvent to obtain a vanadium-negative organic phase and an aqueous phase, wherein the extraction solvent comprises: an extractant, a diluent and a modifier, and the extractant is di(2-ethylhexyl)phosphinic acid; S5 washing the vanadium-bearing organic phase; S6 uses a stripping agent to strip the washed vanadium-negative organic phase to obtain a stripping raffinate and a blank organic phase, and the blank organic phase is returned to S4 as an extraction solvent for recycling; S7 precipitates the stripping raffinate, which is then dried and calcined to obtain vanadium pentoxide.

2. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S1, the acidic vanadium-containing solution includes: 24.8 g / L vanadium, 9.62 g / L manganese, 1.46 g / L magnesium, 0.04 g / L iron, and 0.11 g / L calcium.

3. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S2, the pH of the acidic vanadium-containing solution is 3.0-5.

5. During the impurity removal process, the solution temperature is 25-50°C, the reaction time is 30-90 min, and the amount of impurity remover added is 1-5 times the impurity ion content in the solution.

4. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 3, characterized in that: The impurity removal agent is oxalic acid, and the impurity ions include manganese ions, magnesium ions, iron ions and calcium ions.

5. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S3, the reducing agent is solid sodium sulfite, the amount of sodium sulfite added to the acidic vanadium-containing solution is 50-70 g / L, the reduction temperature is 30-30° C., and the reduction time is 3-10 min.

6. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S4, the amount of the extractant is 5% to 60% of the volume of the negative vanadium organic phase, the volume ratio of the negative vanadium organic phase to the aqueous phase is (0.2:1) to (3:1), the pH of the extraction system is 1.0 to 4.0, the extraction time is 6 to 10 min, and the solution temperature during extraction is 15 to 30°C.

7. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S4, the modifier is tributyl phosphate, and the diluent includes a mixture of any one or more of kerosene, sulfonated kerosene, 260# solvent oil, acetone oxime, methanol, and ethyl acetate.

8. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S5, the volume ratio of the negative vanadium organic phase to the detergent is (1:1) to (1:0.2), the washing time is 5 to 10 minutes, the washing temperature is 15 to 30°C, and the detergent includes: sulfuric acid, deionized water, and hydrogen peroxide.

9. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S6, the concentration of the stripping agent is 0.5-5.0 mol / L, the volume of the negative vanadium organic phase and the stripping agent is (0.2:1)-(3:1), the stripping time is 5-10 min, and the solution temperature during stripping is 15-30°C.

10. The method for preparing high-purity vanadium oxide from vanadium slag according to claim 1, characterized in that: In S7, the calcination temperature is 450-550°C, and the calcination time is 1.5-3.5 hours.

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