阅读说明：本技术 一种全钒液流电池用偏钒酸铵的制备方法 (Preparation method of ammonium metavanadate for all-vanadium redox flow battery ) 是由 董玉明 刘宏辉 张红玲 米界非 张笛 裴丽丽 徐红彬 于 2020-09-08 设计创作，主要内容包括：本发明涉及一种全钒液流电池用偏钒酸铵的制备方法,所述制备方法首先将钒渣、钙基添加剂以及返渣进行焙烧,焙烧时在钙基添加剂以及返渣的作用下,钒渣中含钒尖晶石结构被破坏分解,三价钒高效氧化转化为钒酸钙；然后在近中性有机酸钠溶液中钒酸钙分解,实现了钒的高效浸出；最后浸出液中加入有机酸铵实现浸取剂有机酸钠的转化再生,同时生成全钒液流电池用偏钒酸铵产品。所述制备方法的焙烧过程稳定可控,钒转化率高；浸出过程中的钒浸出率高,浸出过程无铬等杂质浸出；偏钒酸铵结晶完全,产品纯度高,浸取剂有机酸钠再生完全,无外加酸与铵根残留；所述制备方法具有成本低、可连续化生产且无三废排放的优势,具有广阔的应用前景。(The invention relates to a preparation method of ammonium metavanadate for an all-vanadium redox flow battery, which comprises the steps of roasting vanadium slag, a calcium-based additive and return slag, wherein a vanadium-containing spinel structure in the vanadium slag is destroyed and decomposed under the action of the calcium-based additive and the return slag during roasting, and trivalent vanadium is efficiently oxidized and converted into calcium vanadate; then decomposing calcium vanadate in a near-neutral sodium organic acid solution to realize high-efficiency leaching of vanadium; and finally, adding organic acid ammonium into the leachate to realize conversion and regeneration of the leaching agent organic acid sodium, and simultaneously generating an ammonium metavanadate product for the all-vanadium redox flow battery. The roasting process of the preparation method is stable and controllable, and the vanadium conversion rate is high; the vanadium leaching rate in the leaching process is high, and chromium-free impurities are leached in the leaching process; the ammonium metavanadate is completely crystallized, the product purity is high, the leaching agent sodium organic acid is completely regenerated, and no additional acid or ammonium radical is left; the preparation method has the advantages of low cost, continuous production and no three-waste discharge, and has wide application prospect.)

1. A preparation method of ammonium metavanadate for an all-vanadium flow battery is characterized by comprising the following steps:

(1) mixing vanadium slag, calcium-based additive and return slag, and roasting the obtained mixed ingredients to obtain roasted sand;

(2) leaching the calcine obtained in the step (1) by using an organic acid sodium solution, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

(3) converting and regenerating the leachate obtained in the step (2) by using organic acid ammonium, and performing solid-liquid separation after the conversion and regeneration are finished to obtain ammonium metavanadate solid and an organic acid sodium solution; recycling the obtained organic sodium solution in the step (2);

(4) separating the leaching residue obtained in the step (2) to obtain return residue, and reusing the return residue in the step (1);

the step (3) and the step (4) are not in sequence.

2. The method according to claim 1, wherein the method comprises a pretreatment step before step (1): the vanadium slag, the calcium-based additive and the return slag are respectively and independently crushed, ball-milled and screened, so that the particle sizes of the vanadium slag, the calcium-based additive and the return slag are less than or equal to 74 mu m.

3. The method according to claim 1 or 2, wherein the calcium-based additive of step (1) is any one or a combination of at least two of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, organic acid calcium, calcium peroxide, calcium chromite, calcium chromate, calcium manganate, calcium aluminate, and calcium silicate.

4. The preparation method according to claim 3, characterized in that the addition amount of the return slag in the step (1) is 5-80% of the mass of the vanadium slag; CaO and V in the mixed ingredients in the step (1)₂O₅The molar ratio of (0.6-2) to (1).

5. The preparation method as claimed in claim 1 or 4, wherein the roasting in step (1) is aerobic roasting, the roasting temperature is 600-1000 ℃, and the roasting time is 0.2-3 h.

6. The preparation method according to claim 1, wherein the concentration of the sodium organic acid in the step (2) is 30-500g/L, and the organic acid in the sodium organic acid is carboxylic acid;

the carboxylic acid comprises any one or the combination of at least two of humic acid, alginic acid, saturated carboxylic acid or hydroxy acid with the hydroxyl number not more than 4.

7. The preparation method according to claim 6, wherein the liquid-solid ratio of the sodium organic acid solution to the calcine in the step (2) is (1-5):1, and the unit of the liquid-solid ratio is mL/g;

the leaching temperature in the step (2) is 25-100 ℃, and the leaching time is 20-180 min.

8. The method according to claim 6, wherein the organic acid in the ammonium organic acid used in step (3) is the same as the organic acid in the sodium organic acid used in step (2);

NH in the organic acid ammonium in the step (3)₄ ⁺And V in the leaching solution obtained in the step (2)₂O₅The molar ratio of (1.5-2) to (1).

9. The method of claim 1, wherein the sorting of step (4) comprises any one of or a combination of at least two of reverse flotation, gravity separation, magnetic separation, or electric separation;

fe in the return slag obtained in the step (4)₂O₃The mass fraction of the component (A) is more than or equal to 50 percent.

10. The method of claim 1, further comprising a washing step:

respectively carrying out multi-stage countercurrent washing on the leaching residue obtained in the step (2) and the ammonium metavanadate solid obtained in the step (3) to obtain a washing liquid and a washed solid; the washing liquid returns to the step (2) for recycling; washing the leaching residue obtained in the step (2) and then using the washed leaching residue for sorting in the step (4); and (4) washing the ammonium metavanadate solid obtained in the step (3) to obtain the ammonium metavanadate solid for the all-vanadium redox flow battery.

Technical Field

The invention belongs to the technical field of vanadium slag utilization, relates to a method for extracting vanadium from vanadium slag to prepare high-purity vanadium, and particularly relates to a preparation method of ammonium metavanadate for an all-vanadium redox flow battery.

Background

Vanadium titano-magnetite is the main mineral of vanadium resources in the world, and 88% of the world's vanadium production is obtained from vanadium titano-magnetite. The vanadium titano-magnetite resource reserves in China are rich and are mainly distributed in Panzhihua, Chengde and Maanshan areas. The vanadium titano-magnetite contains vanadium, titanium, chromium, iron and other multiple metals which are symbiotic, and has high resource utilization value. The vanadium slag is slag with high vanadium content obtained by smelting vanadium-titanium magnetite into molten iron and then oxidizing and blowing, and the vanadium slag is a main raw material for extracting vanadium in China at present.

The main methods for extracting vanadium from vanadium slag comprise a pyrogenic process and a wet process, and the wet process mainly comprises an oxygen pressure acid leaching method and a sub-molten salt alkaline leaching method. V-Fe-H in converter vanadium slag oxygen pressure acid leaching process of Zhang an et al₂The potential-pH diagram of O series, Chinese non-ferrous metals academic report 2011,21(11):2936-₂SO₄Under the condition, the leaching rate of vanadium is 96.87 percent, and the leaching rate of iron is 89.25 percent. CN 105238922A and the literature, "yebin et al. research on the roasting-free pressure acid leaching process of vanadium slag rare metals 2014,38(06): 1134-.

The vanadium slag often contains 1-15% of Cr₂O₃The oxygen pressure acid leaching method has the problems that a large amount of metal elements are dissolved out, so that the vanadium solution can be purified in multiple steps to produce vanadium products, the purification difficulty is high, the cost is high, and a large amount of dangerous solid waste is generated in the purification process to pollute the environment.

The technical scheme disclosed by CN 102127655A, CN 105400967A, CN 103060843A and CN 104294040A adopts a sub-molten salt process to leach vanadium by high-temperature high-pressure strong alkali, and the leachate is evaporated, cooled and crystallized to obtain a sodium orthovanadate product. The main problems of the sub-molten salt and strong alkali leaching are that the content of impurities such as silicon, aluminum and the like is high, the purity of vanadium and chromium products is not high due to mutual entrainment, and sodium orthovanadate is only an intermediate product.

The wet vanadium extraction method has the advantages of low reaction temperature compared with a fire method, but has the disadvantages of harsh reaction conditions, high equipment requirements, no leaching of various components such as selective vanadium oxide, chromium and the like, and the problems of waste water, dangerous waste residues and the like, and is difficult to industrially apply.

The method for extracting vanadium in the prior production is mainly a pyrogenic process, the traditional pyrogenic process vanadium extraction process is a sodium salt roasting water immersion method, sodium carbonate, sodium chloride or sodium sulfate and other sodium salt additives are added under the roasting condition of 700 plus 800 ℃, sodium and vanadium which is oxidized into pentavalent vanadium are combined to form water-soluble sodium vanadate, the vanadium clinker is immersed in water to obtain a sodium metavanadate solution, and a vanadium product is obtained through a vanadium precipitation process.

CN 108251636A, CN 108179265A, CN 105734307A, CN 102923774A, CN107586948A, CN 105087940A and CN 106947875A disclose a process for extracting vanadium by sodium salt roasting. The method for leaching vanadium by sodium salt roasting water has the main problems that harmful gases such as chlorine gas, sulfur dioxide and the like are generated by roasting, and roasting equipment is formed and the extraction and production efficiency of vanadium is influenced because the roasting process is unstable, various sodium salts with low melting points are generated, the liquid phase amount is large, and the material sintering condition is easy to generate.

In order to avoid the problem of equipment ring formation caused by excessive liquid phase quantity, a large amount of vanadium extraction tailings are required to be added during sodium salt roasting mixing, but the vanadium extraction tailings still contain a large amount of silicate, and sodium salt is additionally consumed during roasting, so that the extraction of vanadium cannot be effectively promoted. Moreover, although the addition of the tailings reduces the problem of sintering of the roasted material, a large amount of mirabilite is formed in the neutralization process of the alkaline leaching solution, and the energy consumption of wastewater treatment is high. And the sodium roasting process has no selectivity on the oxidation of vanadium, chromium is leached in a large amount, a large amount of vanadium-chromium reducing slag is produced and discharged by the process, the impurity content of the leaching solution is high, and the purity of a vanadium product is low.

In order to reduce the leaching of chromium, the processes of CN 105219976A, CN 106987716A, CN 105110373A, CN106521191A, CN 106179771A, CN 103993161A, CN 104357660A, CN 104357652A, CN103993160A and the like adopt a calcification roasting-sulfation/carbonation leaching method to extract vanadium, a calcareous additive is added during roasting to generate calcium vanadate, and then sulfation/carbonation leaching is adopted by utilizing the principle that the solubility product of calcium sulfate/calcium carbonate is less than that of calcium vanadate.

The advantages of the calcification roasting process are that no toxic gas is generated, the oxidation selectivity to vanadium is high, and the leaching amount of chromium is less. The problems that the calcification roasting temperature is higher, substances such as vanadate and the like are melted at high temperature, the liquid phase content of vanadium slag is higher, and therefore, the sintering is easy to cause the ring formation of roasting equipment, the roasting time is longer, and the production efficiency is reduced are caused. When sulfuric acid is leached, the leachate needs to be neutralized, so that a large amount of gypsum waste residue is generated; when sodium carbonate/sodium bicarbonate is leached, the pH of the leaching solution is still high, sulfuric acid is required to be added or carbon dioxide is introduced for neutralization in order to obtain ammonium metavanadate/polyvanadate, and sodium sulfate wastewater can still be generated when sulfuric acid is added to adjust the pH or ammonium sulfate is adopted to precipitate vanadium; carbon dioxide is introduced to adjust the pH value to generate sodium bicarbonate sediment with low solubility, and ammonium carbonate/ammonium bicarbonate is added to precipitate vanadium, so that the vanadium precipitation rate is low, continuous production cannot be realized, and a large amount of ammonium salt wastewater is generated; in addition, the leaching agent adopts acid or alkali with higher concentration, so that the impurity content in the leaching solution is still higher, and the purity of the vanadium product is low.

The method for extracting vanadium from vanadium slag by using ammonium salt disclosed in CN 102560086A, CN 103952565A, CN 104164569A, CN 108149022A, CN 104694769A, CN 106676273A and the like has the advantages that a near-neutral ammonium salt leaching agent is adopted for leaching, so that a relatively pure vanadium leaching solution is obtained, the purification pressure of the vanadium leaching solution is reduced, and a vanadium product with relatively high purity can be directly obtained. However, the method has the problems that ammonium salts such as ammonium bicarbonate and the like are easy to decompose to generate ammonia gas to pollute the environment, and the problems of small solubility of ammonium metavanadate, high calcification/blank roasting temperature, low vanadium extraction rate, low production efficiency and the like in an ammonium salt solution exist. CN 105779758A, CN 105714102A, CN 103146930A, CN 110408772A and the like adopt ammonium phosphate, ammonium oxalate and ammonium sulfate which are not easy to decompose to leach vanadium slag clinker, and the method avoids the environmental pollution of ammonia gas, but still has the problems of small solubility of ammonium metavanadate in ammonium salt solution, high calcification/blank roasting temperature, low vanadium extraction rate, low production efficiency and the like.

Therefore, the roasting process of the existing vanadium slag vanadium extraction process has the problems of high temperature, easy sintering, low vanadium extraction rate and easy leaching of chromium; the leaching process adopts high-concentration acid or alkali leaching, the vanadium product has low purity, a large amount of wastewater and dangerous solid wastes such as mirabilite and gypsum are generated, or near-neutral ammonium salt leaching is adopted, the ammonium salt is easy to decompose to generate ammonia pollution, the solubility of ammonium metavanadate in leaching solution is low, the production efficiency is low, and the like.

In combination with the rapid development of all-vanadium redox flow batteries in recent years, the demand of high-purity vanadium products is continuously increased. The development of a clean vanadium slag extraction method which has the advantages of stable roasting process, high vanadium extraction rate, high vanadium product purity and low process cost, can realize continuous production and does not discharge three wastes is urgently needed to realize the high-efficiency extraction of vanadium and the preparation of a high-purity vanadium product for a vanadium flow battery.

Disclosure of Invention

The invention aims to provide a preparation method of ammonium metavanadate for an all-vanadium redox flow battery, which has no under-burning and sintering phenomena within a wide temperature range, stable and controllable roasting process and high vanadium conversion rate; the vanadium leaching rate in the leaching process is high, and no impurity is leached in the leaching process; the ammonium metavanadate is completely crystallized, the product purity is high, the leaching agent sodium organic acid is completely regenerated, and no additional acid or ammonium radical is left; the preparation method has the advantages of low cost, continuous production and no three-waste discharge, and has wide application prospect.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of ammonium metavanadate for an all-vanadium redox flow battery, which comprises the following steps:

(1) mixing vanadium slag, calcium-based additive and return slag, and roasting the obtained mixed ingredients to obtain roasted sand;

(2) leaching the calcine obtained in the step (1) by using an organic acid sodium solution, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

(3) converting and regenerating the leachate obtained in the step (2) by using organic acid ammonium, and performing solid-liquid separation after the conversion and regeneration are finished to obtain ammonium metavanadate solid and an organic acid sodium solution; recycling the obtained organic sodium solution in the step (2);

(4) separating the leaching residue obtained in the step (2) to obtain return residue, and reusing the return residue in the step (1);

the step (3) and the step (4) are not in sequence.

The preparation method provided by the invention comprises the steps of mixing vanadium slag, calcium-based additive and return slag, wherein under the action of the calcium-based additive and the return slag during roasting, a vanadium-containing spinel structure in the vanadium slag is destroyed and decomposed, and trivalent vanadium is efficiently oxidized into calcium vanadate. And finally, adding organic acid ammonium into the leachate to realize conversion and regeneration of the leaching agent, and simultaneously generating an ammonium metavanadate product for the all-vanadium redox flow battery.

According to the preparation method provided by the invention, in the process of preparing the ammonium metavanadate for the all-vanadium redox flow battery, the roasting process is stable and controllable, and the high conversion rate of vanadium is realized; no impurity is leached in the leaching process; the ammonium metavanadate is completely crystallized, and the product purity is high; the leaching agent sodium organic acid is completely regenerated, and no ammonium radical remains. The preparation method provided by the invention has the advantages of low cost, continuous production, no three-waste discharge and the like.

Preferably, the preparation method comprises a pretreatment step before the step (1): the vanadium slag, the calcium-based additive and the return slag are respectively and independently crushed, ball-milled and screened, so that the particle sizes of the vanadium slag, the calcium-based additive and the return slag are less than or equal to 74 mu m.

Preferably, the particle size of the vanadium slag, the calcium-based additive and the return slag is smaller than or equal to 74 microns, so that the ball-milled material is sieved by a 200-mesh sieve to obtain the vanadium slag, the calcium-based additive and the return slag with the particle size smaller than or equal to 74 microns.

Preferably, the calcium-based additive in step (1) is any one or a combination of at least two of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, organic calcium, calcium peroxide, calcium chromite, calcium chromate, calcium manganate, calcium aluminate and calcium silicate; typical but non-limiting combinations include a combination of calcium oxide and calcium carbonate, a combination of calcium hydroxide, organic acid calcium and calcium peroxide, a combination of calcium oxide, calcium chromite, calcium chromate and calcium manganate, or a combination of calcium oxide, calcium carbonate, calcium manganate, calcium aluminate and calcium silicate, and the like.

The organic acid calcium is formed by combining calcium ions and organic matters, and comprises but is not limited to any one or the combination of at least two of calcium malonate, calcium humate or calcium alginate; calcium carbonate, calcium bicarbonate, organic acid calcium and calcium peroxide generate pores during roasting; the calcium peroxide, the calcium chromate and the calcium manganate can release fresh oxygen in the roasting process; calcium chromite and calcium chromate decompose to chromium oxide during calcination due to V³⁺And Cr³⁺Of not much different ionic radii of Cr³⁺Easily form a solid solution with iron, thereby forming a solid solution with V³⁺Strive for iron in the ferrovanadium solid solution, has promoted the decomposition of the spinel; the calcium aluminate and the calcium silicate are decomposed to generate silica and alumina inert components, the silica and the alumina have higher melting points and cannot be melted in the roasting temperature range, and the effect of diluting the liquid phase is achieved.

As a preferred technical solution of the present invention, the calcium-based additive is a combination of calcium oxide, calcium hydroxide, calcium carbonate, calcium bicarbonate, organic calcium, calcium peroxide, calcium chromite, calcium chromate, calcium manganate, calcium aluminate, and calcium silicate; wherein calcium carbonate, calcium bicarbonate, organic acid calcium and calcium peroxide are decomposed to generate pores in the roasting process; the calcium peroxide, the calcium chromate and the calcium manganate release fresh oxygen in the roasting process; the calcium chromite and the calcium chromate are decomposed in the roasting process, and are combined with ferric iron to destroy the vanadium iron spinel coating, so that unoxidized vanadium iron spinel is exposed, oxidized pentavalent vanadium is combined with calcareous materials, the vanadium slag is promoted to be decomposed and oxidized completely, the roasting time of the vanadium slag is shortened, and the conversion rate of vanadium is improved; the calcium aluminate and the calcium silicate are decomposed to generate silica and alumina inert components, and the silica and alumina inert components have higher melting points and do not melt within the roasting temperature range of the vanadium slag, thereby playing the role of diluting the liquid phase quantity.

The return slag is Fe₂O₃The mass fraction of the enrichment substances of iron, vanadium and chromium which are more than or equal to 50 percent, namely iron oxide, chromium iron solid solution, ferrovanadium solid solution and vanadium chromium iron solid solution, wherein the iron oxide plays a role of diluting a liquid phase in the roasting process, the solid solution in the slag returned in the roasting process is partially decomposed, and Cr in the chromium oxide³⁺And V³⁺Compete for iron in the ferrovanadium solid solution, promote the decomposition of spinel and the solid solution and improve the conversion rate of vanadium. Vanadium which is not oxidized in the ferrovanadium solid solution is oxidized, so that the effect of deep vanadium extraction is achieved.

Preferably, the calcium-based additive comprises a first calcium source, a second calcium source, a third calcium source, a fourth calcium source and a fifth calcium source; the first calcium source comprises calcium oxide and calcium hydroxide; the second calcium source comprises calcium carbonate, calcium bicarbonate and organic calcium; the third calcium source comprises calcium peroxide and calcium manganate; the fourth calcium source comprises calcium chromate and calcium chromite; the fifth calcium source comprises calcium aluminate and calcium silicate. 1-30 parts by weight of a first calcium source in the calcium-based additive; 1-20 parts of a second calcium source; 1-20 parts of a third calcium source; the fourth calcium source is 5-30 parts; the fifth calcium source is 20-60 parts.

The weight part of the first calcium source is 1-30 parts, such as 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts or 30 parts, but is not limited to the recited values, and other values not recited in the numerical range are also applicable; the weight part of the second calcium source is 1-20 parts, such as 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, 12 parts, 15 parts, 16 parts, 18 parts or 20 parts, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable; the weight part of the third calcium source is 1-20 parts, such as 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, 12 parts, 15 parts, 16 parts, 18 parts or 20 parts, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable; the weight part of the fourth calcium source is 5-30 parts, such as 5 parts, 10 parts, 15 parts, 20 parts, 25 parts or 30 parts, but is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable; the weight part of the fifth calcium source is 20-60 parts, for example, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts or 60 parts, but is not limited to the enumerated values, and other unrecited values within the numerical range are also applicable.

Preferably, the addition amount of the return slag in the step (1) is 5-80% of the mass of the vanadium slag; for example, the concentration may be 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 65%, 70%, or 80%, but is not limited to the recited values, and other values not recited within the range of values are also applicable. CaO and V in the mixed ingredients in the step (1)₂O₅The molar ratio of (1: 0.6) to (0.6: 1) may be, for example, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.25:1, 1.5:1, 1.75:1, 1.9:1 or 2:1, but is not limited to the values listed, and other values not listed in the numerical range are also applicable, and (0.8-1.5: 1) is preferable.

Preferably, the calcination in step (1) is aerobic calcination, and the calcination temperature is 600-1000 ℃, such as 600 ℃, 650 ℃, 700 ℃, 725 ℃, 750 ℃, 780 ℃, 800 ℃, 825 ℃, 850 ℃, 875 ℃, 900 ℃, 925 ℃, 950 ℃ or 1000 ℃, but not limited to the cited values, and other unrecited values within the range of values are equally applicable, preferably 700-800 ℃.

According to the invention, the aim of controlling the alkalinity of the mixture is achieved by adjusting the addition amount of the calcium-based additive, and the vanadium slag can selectively oxidize vanadium and not oxidize chromium in a proper roasting temperature range and in an oxidizing environment, so that no chromium is leached out in subsequent leachate.

The baking time is 0.2 to 3 hours, for example, 0.2 hour, 0.25 hour, 0.3 hour, 0.5 hour, 0.75 hour, 0.9 hour, 1 hour, 1.5 hour, 2 hours, 2.5 hours or 3 hours, but not limited to the values listed, and other values not listed in the numerical range are also applicable, preferably 0.25 to 2 hours, and more preferably 0.3 to 1 hour.

According to the invention, through the addition of the calcium-based additive and the return slag, the spinel phase in the vanadium slag can be fully decomposed at the roasting temperature of 600-1000 ℃, so that the phenomenon of under-roasting is avoided in a wider roasting range, and the roasting process is stable and reliable.

Preferably, the concentration of the sodium organic acid in the step (2) is 30-500g/L, such as 30g/L, 50g/L, 60g/L, 75g/L, 100g/L, 120g/L, 150g/L, 175g/L, 200g/L, 225g/L, 250g/L, 300g/L, 350g/L, 400g/L, 425g/L, 475g/L or 500g/L, but not limited to the recited values, and other values not recited in the range of values are equally applicable, preferably 50-250 g/L; the organic acid in the organic acid sodium is carboxylic acid.

The carboxylic acid comprises any one or the combination of at least two of humic acid, alginic acid, saturated carboxylic acid or hydroxy acid with the hydroxyl number not more than 4.

The hydroxy acid with the hydroxyl number not more than 4 is a hydroxyl derivative of saturated carboxylic acid.

The saturated carboxylic acid includes a saturated monocarboxylic acid and/or a saturated polycarboxylic acid.

Preferably, the saturated monocarboxylic acid and the hydroxy acid corresponding to the saturated monocarboxylic acid and having the hydroxyl number not more than 4 contain 5 to 9 carbon atoms; exemplary saturated monocarboxylic acids and their corresponding hydroxy acids having a hydroxyl number of no greater than 4 include: valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, benzoic acid, phenylacetic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 3-ethylpentanoic acid, 2-propylpentanoic acid, 4-methyl-2-propylpentanoic acid, 2-hydroxypentanoic acid, 3-hydroxypentanoic acid, 4-hydroxypentanoic acid, 5-hydroxypentanoic acid, 3-hydroxy-3-methylpentanoic acid, 2-hydroxy-2, 4-dimethylpentanoic acid, 2-hydroxy-4-methylpentanoic acid, 2-dimethylpentanoic acid, 2, 3-dimethylpentanoic acid, 2, 4-dimethylpentanoic acid, 2-propyl-5-hydroxypentanoic acid, 2, 3-dihydroxy-3-methylpentanoic acid, 2,3-, 3, 5-dihydroxy-3-methylpentanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 3,5, 5-trimethylhexanoic acid, 2, 2-dimethylhexanoic acid, 5, 5-dimethylhexanoic acid, 2, 4-dimethylhexanoic acid, 2-ethylhexanoic acid, 4-ethylhexanoic acid, 2-propylhexanoic acid, 3-hydroxycaproic acid, 4-hydroxycaproic acid, 5-hydroxycaproic acid, 6-hydroxycaproic acid, 3-hydroxy-3-methylhexanoic acid, 3-hydroxy-5-methylhexanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 5-methylheptanoic acid, 2-ethylheptanoic acid, 2-methylheptanoic acid, 2, 6-dimethylheptanoic acid, 3-hydroxyheptanoic acid, 5-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 2-methyloctanoic acid, 4-methyloctanoic acid, 7-methyloctanoic acid, 2-hydroxyoctanoic acid, 4-hydroxyoctanoic acid, 6-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 2-hydroxynonanoic acid, 9-hydroxynonanoic acid, o-hydroxybenzoic acid (salicylic acid), p-hydroxybenzoic acid, m-hydroxybenzoic acid, 3, 4-dihydroxybenzoic acid, 2, 3-dihydroxybenzoic acid, 2, 4-dihydroxybenzoic acid, 2, 5-dihydroxybenzoic acid, 3,4, 5-trihydroxybenzoic acid (gallic acid), 2,4, 6-trihydroxybenzoic acid, 2-hydroxy-6-methylbenzoic acid, 2-methyl-3-hydroxybenzoic acid, 2-hydroxy-6-methylbenzoic acid, Any one or a combination of at least two of 2, 5-dimethyl-3-hydroxybenzoic acid, 3, 5-dihydroxy-4-methylbenzoic acid, 2,4, 6-trimethylbenzoic acid, 3-methylphenylacetic acid, 4-methylphenylacetic acid, 2-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid, 3, 4-dihydroxyphenylacetic acid, 2, 6-dihydroxyphenylacetic acid or 4-hydroxymethylphenylacetic acid is suitable, but not limited to the examples listed, and other monocarboxylic acids in the range containing carbon atoms and their corresponding hydroxy acids having a hydroxyl number of not more than 4 are equally suitable.

Preferably, the saturated polycarboxylic acid and the hydroxy acid corresponding to the saturated polycarboxylic acid and having the hydroxyl number not more than 4 contain 3-10 carbon atoms; exemplary saturated polycarboxylic acids and their corresponding hydroxy acids having a hydroxyl number of no greater than 4 include malonic acid (carotic acid), succinic acid (succinic acid), glutaric acid (glycolic acid), adipic acid (adipic acid), pimelic acid (syzygoic acid), suberic acid (suberic acid), azelaic acid (azelaic acid), sebacic acid (sebacylic acid), methylmalonic acid (isosuccinic acid), hydroxymalonic acid (tartaric acid), phthalic acid, isophthalic acid, terephthalic acid, 2, 3-dimethylsuccinic acid, 2, 3-diethylsuccinic acid, 2-methyl-2-ethylsuccinic acid, 2-isopropylsuccinic acid, 2-hydroxysuccinic acid (malic acid), 2, 3-dihydroxysuccinic acid (tartaric acid), 2-hydroxy-2-methylsuccinic acid, 2-hydroxyglutaric acid, 3-hydroxyglutaric acid, 2, 4-dimethylglutaric acid, 3-dimethylglutaric acid, 2, 4-diethylglutaric acid, 3-propylglutaric acid, 3-butylglutaric acid, 3-hydroxy-3-methylglutaric acid, 2-hydroxy-3-carboxyglutaric acid (citric acid), 1-hydroxy-3-carboxyglutaric acid (isocitric acid), 2,3, 4-trihydroxyglutaric acid, 2-hydroxyadipic acid, 2, 5-dihydroxyadipic acid, 3-tert-butyladipic acid, 2, 5-diethyladipic acid, 3-methyl-3-ethyladipic acid, 3-hydroxy-3-methyladipic acid, 2-ethyl-5-hydroxyadipic acid, 3-hydroxy-3-ethyladipic acid, 2-hydroxypimelic acid, 2, 6-dimethylpimelic acid, 5-methyl-2-ethylpimelic acid, 4-isopropylpimelic acid, 4-dimethylpimelic acid, 4-methyl-4-ethylpimelic acid, 2-methyl-6-hydroxypimelic acid, 4-dihydroxypimelic acid, 2, 4-dihydroxypimelic acid, 4-methyl-2, 6-dihydroxypimelic acid, 2-hydroxysuberic acid, 3-hydroxysuberic acid, 2, 7-dihydroxysuberic acid, 2-methylsuberic acid, 2-methyl-7-hydroxysuberic acid, 2, 7-dimethylsuberic acid, 2-hydroxyazelaic acid, 3-hydroxyazelaic acid, 2-methylazelaic acid, 2-hydroxysebacic acid, 2-hydroxysuberic acid, 2-dimethylpimelic acid, 4-, Any one or a combination of at least two of 3-hydroxysebacic acid, 4-methylphthalic acid, 5-methylisophthalic acid, 2-methylphthalic acid, 4-hydroxyphthalic acid, 5-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 3-hydroxyphthalic acid, 3, 6-dihydroxyphthalic acid, 2, 5-dihydroxyterephthalic acid, 4, 6-dihydroxyisophthalic acid, 2, 5-dihydroxy-1, 4-phenylenediacetic acid, 1,2, 4-benzenetricarboxylic acid, 1,2, 3-benzenetricarboxylic acid, 1,3, 5-benzenetricarboxylic acid, or 2-hydroxybenzenetricarboxylic acid, but is not limited to the exemplified examples, other polycarboxylic acids in the carbon number range and their corresponding hydroxy acids having a hydroxyl number of no greater than 4 are equally suitable.

Preferably, the liquid-solid ratio of the sodium organic acid solution to the calcine in the step (2) is (1-5):1, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, but not limited to the enumerated values, and other unrecited values within the numerical range are also applicable, and the unit of the liquid-solid ratio is mL/g.

The temperature of the leaching in the step (2) is 25 to 100 ℃, and for example, the temperature may be 25 ℃, 30 ℃, 40 ℃, 45 ℃, 50 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃ or 100 ℃, but is not limited to the enumerated values, and other values not enumerated in the numerical range are also applicable, and preferably 40 to 70 ℃; the leaching time is 20-180min, such as 20min, 30min, 40min, 50min, 60min, 75min, 80min, 90min, 100min, 110min, 120min, 135min, 150min or 180min, but not limited to the values listed, and other values not listed in the range of values are equally applicable, preferably 60-120 min.

According to the method, specific sodium organic acid is used as a leaching agent, so that the combination of pentavalent vanadium and calcium in the calcine can be decomposed, organic acid calcium precipitate is generated, and vanadium is replaced and completely dissolved into a solution by utilizing the characteristic of high solubility of sodium vanadate, so that the leaching rate of vanadium is improved; and the pH of the sodium organic acid leaching agent adopted by the invention is near neutral, so that vanadium in the leaching solution exists in the form of sodium metavanadate, the leaching amount of other impurities is less, the subsequent procedures of pH adjustment and impurity removal are omitted, and the high-purity ammonium metavanadate for the vanadium flow battery can be obtained.

Preferably, the organic acid in the organic acid ammonium used in step (3) is the same as the organic acid in the organic acid sodium used in step (2).

NH in the organic acid ammonium in the step (3)₄ ⁺And V in the leaching solution obtained in the step (2)₂O₅The molar ratio of (1.5-2):1, for example, 1.5:1, 1.55:1, 1.6:1, 1.62:1, 1.7:1, 1.75:1, 1.8:1, 1.88:1, 1.9:1 or 2:1, but is not limited to the values recited, and other values not recited in the numerical range are also applicable.

After the sodium metavanadate leachate is obtained, the organic acid ammonium with the same organic acid component as the organic acid sodium is added, under the action of the organic acid ammonium, the temperature and the pH do not need to be adjusted, and the ammonium metavanadate can be quickly dissolved out and crystallized to reach Na⁺、NH₄ ⁺The purpose of ion conversion is to realize the regeneration of the sodium organic acid leaching agent.

Because the specific sodium organic acid is used for leaching, impurity-free leaching is realized, and the pH of the leaching solution does not need to be adjusted, so that the purity of the vanadium product is higher. The invention controls the amount of organic acid ammonium, NH₄ ⁺The addition amount does not exceed the theoretical requirement amount of precipitated ammonium metavanadate, and the dissolution and crystallization of the ammonium metavanadate are thorough, so that almost no NH remains in the regenerated sodium organic acid solution₄ ⁺And the problem of environmental pollution caused by ammonia gas and the like can not be generated when the organic sodium acid solution returns to the leaching process.

In order to sufficiently perform the transformation regeneration, the time of the transformation regeneration is at least 5min, preferably 5-60min, and may be, for example, 5min, 7min, 9min, 10min, 15min, 20min, 23min, 25min, 30min, 40min, 45min, 50min, 57min or 60min, but is not limited to the enumerated values, and other unrecited values within the numerical range are also applicable.

Preferably, the sorting in step (4) comprises any one of or a combination of at least two of reverse flotation, gravity separation, magnetic separation or electric separation, and typical but non-limiting combinations comprise a combination of reverse flotation, gravity separation and magnetic separation, a combination of reverse flotation, magnetic separation and electric separation, or a combination of reverse flotation, gravity separation, magnetic separation and electric separation.

Fe in the return slag obtained in the step (4)₂O₃The mass fraction of the component (A) is more than or equal to 50 percent.

The return slag obtained in the step (4) of the invention is Fe₂O₃The mass fraction of the concentrate of iron, vanadium and vanadium is more than or equal to 50 percent, wherein Fe₂O₃Is 50%, 51%, 55%, 60%, 65%, 67%, 70%, 75%, 80%, 85% or 90%, but is not limited to the recited values, and other unrecited values within the numerical range are equally applicable.

According to the invention, minerals such as organic acid calcium, olivine, pyroxene and the like in the leaching residue can be removed through reverse flotation; by utilizing the difference of the iron oxide, the chromium oxide, the iron oxide solid solution, the spinel and the like in density, granularity, magnetism and electric properties with gangue components, the returned slag containing the iron oxide, the chromium oxide, the iron oxide solid solution and the spinel can be obtained by selective separation through gravity separation, magnetic separation and electric separation; moreover, the leached slag often contains 1.5-20% of chromium oxide, and the chromium in the leached slag is enriched through sorting; therefore, the leaching slag separation can effectively utilize beneficial components in the leaching slag to promote the roasting process and achieve the effect of deep vanadium extraction.

Preferably, the preparation method further comprises a washing step:

respectively carrying out multi-stage countercurrent washing on the leaching residue obtained in the step (2) and the ammonium metavanadate solid obtained in the step (3) to obtain a washing liquid and a washed solid; the washing liquid returns to the step (2) for recycling; washing the leaching residue obtained in the step (2) and then using the washed leaching residue for sorting in the step (4); and (4) washing the ammonium metavanadate solid obtained in the step (3) to obtain the ammonium metavanadate solid for the all-vanadium redox flow battery.

Preferably, when the leaching residue is subjected to multistage countercurrent washing in step (2), the solid-to-liquid ratio of the leaching residue to the washing water is (0.3-1):1, for example, 0.3:1, 0.35:1, 0.4:1, 0.5:1, 0.6:1, 0.65:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but not limited to the values listed, and other values not listed within the range of values are equally applicable, and the unit of the solid-to-liquid ratio is mL/g.

The method adopts near-neutral sodium organic acid for leaching, and impurities in the calcine are hardly dissolved out, so that the ammonium metavanadate obtained by conversion and regeneration is less in impurity content and only contains a small amount of sodium organic acid leaching agent. According to the invention, the organic sodium acid is washed out and recycled through multi-stage countercurrent washing, and meanwhile, the ammonium metavanadate with extremely low impurity content for the all-vanadium redox flow battery is obtained.

As a preferable technical scheme of the preparation method, the preparation method comprises the following steps:

(1) the vanadium slag, the calcium-based additive and the return slag are respectively and independently crushed, ball-milled and screened, so that the particle sizes of the vanadium slag, the calcium-based additive and the return slag are less than or equal to 74 mu m; then mixing the vanadium slag, the calcium-based additive and the return slag after the screening treatment to obtain a mixed ingredient; the addition amount of the return slag is 5-80% of the mass of the vanadium slag, and CaO and V in the mixed ingredients₂O₅The molar ratio of (0.6-2) to 1; roasting with oxygen at 600-;

(2) leaching the roasted product obtained in the step (1) at 25-100 ℃ for 20-180min by using an organic acid sodium solution with the concentration of 30-500g/L, wherein the solid-to-solid ratio of a leaching solution is (1-5) to 1; after leaching, carrying out solid-liquid separation to obtain a leaching solution and leaching residues; adding washing water into the obtained leaching residues for countercurrent washing, wherein the liquid-solid ratio of the leaching residues to the washing water is (0.3-1) to 1, the washed leaching residues are used for sorting in the step (4), and the washing liquid is reused for leaching in the step (2); the unit of the liquid-solid ratio is mL/g;

(3) using organic acid ammonium to transform the leaching obtained in the regeneration step (2)Discharging liquid, controlling NH in organic acid ammonium₄ ⁺With V in the leach liquor₂O₅The molar ratio of (1.5-2) to (1), the conversion regeneration time is 5-60min, and after the conversion regeneration is finished, solid-liquid separation is carried out to obtain ammonium metavanadate solid and organic acid sodium solution; adding washing water into the ammonium metavanadate solid to carry out countercurrent washing, wherein the washed solid is the ammonium metavanadate for the all-vanadium redox flow battery, and the washing liquid is reused for leaching in the step (2); the obtained sodium organic acid solution is reused for leaching in the step (2);

(4) separating the washed leaching residue obtained in the step (2) to obtain returned residue, wherein the returned residue is Fe₂O₃The iron, vanadium and chromium enrichment with the content of 53wt% is recycled in the step (1).

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method provided by the invention comprises the steps of mixing vanadium slag, calcium-based additive and return slag, wherein under the action of the calcium-based additive and the return slag during roasting, a vanadium-containing spinel structure in the vanadium slag is destroyed and decomposed, and trivalent vanadium is efficiently oxidized into calcium vanadate. Decomposing sodium vanadate in a near-neutral organic sodium vanadate solution to realize high-efficiency leaching of vanadium, finally adding organic acid ammonium into a leaching solution to realize conversion and regeneration of a leaching agent, and simultaneously generating an ammonium metavanadate product for the all-vanadium redox flow battery;

(2) in the calcium-based additive selected by the invention, calcium carbonate, calcium bicarbonate, organic acid calcium and calcium peroxide generate pores during roasting; the calcium peroxide, the calcium chromate and the calcium manganate can release fresh oxygen in the roasting process; calcium chromite and calcium chromate decompose to chromium oxide during calcination due to V³⁺And Cr³⁺Of not much different ionic radii of Cr³⁺Easily form a solid solution with iron, thereby forming a solid solution with V³⁺Strive for iron in the ferrovanadium solid solution, has promoted the decomposition of the spinel; calcium aluminate and calcium silicate are decomposed to generate silica and alumina inert components, the silica and alumina have higher melting points and cannot be melted in the roasting temperature range, and the effect of diluting a liquid phase is achieved; the added amount of the calcium-based additive controls the alkalinity of the vanadium slag to realize selective oxidation of vanadium and no chromium oxideSo that no chromium is dissolved out of the leaching solution;

(3) according to the invention, by sorting the leaching slag, ferric oxide and chromium oxide in the leaching slag can be effectively utilized, wherein the ferric oxide plays a role in diluting a liquid phase, the chromium oxide promotes the decomposition of spinel and solid solution, the conversion rate of vanadium is improved, the effect of deep vanadium extraction of the leaching slag is achieved, and the high-efficiency utilization of resources is realized;

(4) according to the invention, sodium organic acid is selected as a leaching agent, so that the combination of pentavalent vanadium and calcium in the calcine can be decomposed to generate organic acid calcium precipitate, and the vanadium can be replaced and completely dissolved into the leaching solution by utilizing the characteristic of high solubility of sodium vanadate, so that the leaching rate of the vanadium is improved and is more than 97%; the near-neutral leaching agent enables vanadium in the leaching solution to exist in a sodium metavanadate form, the leaching amount of other impurities is less, the subsequent procedures of pH adjustment and impurity removal are omitted, and the high-purity ammonium metavanadate for the vanadium flow battery is favorably obtained;

(5) the invention carries out conversion and regeneration by adding the organic acid ammonium, can realize the rapid dissolution crystallization of the ammonium metavanadate without adjusting the temperature and the pH value to reach Na⁺And NH₄ ⁺The purpose of ion conversion is realized, the regeneration of the sodium organic acid leaching agent is realized, and the purity of ammonium metavanadate exceeds 99.5 percent; and NH₄ ⁺The addition amount is not more than the theoretical requirement amount of precipitated ammonium metavanadate, and the dissolution and crystallization of the ammonium metavanadate are thorough, so that almost no NH remains in the regenerated sodium organic acid solution₄ ⁺The problem of environmental pollution caused by ammonia gas and the like can not be generated when the organic sodium acid solution returns to the leaching process;

(6) in the preparation method provided by the invention, the leaching agent is completely recycled, no acid is added, no impurity removal operation is performed, continuous production can be performed, the production efficiency is high, no three wastes are discharged, the production cost is low, the purity of the ammonium metavanadate product is high, and the requirements of the first-grade standard (GB/T37204-2018) for preparing the electrolyte for the all-vanadium flow battery are met.

Drawings

FIG. 1 is a process flow diagram of a preparation method provided by the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The specific embodiment of the invention provides a preparation method of ammonium metavanadate for an all-vanadium redox flow battery, and a process flow chart of the preparation method is shown in figure 1, and the preparation method comprises the following steps:

(1) mixing vanadium slag, calcium-based additive and return slag, and roasting the obtained mixed ingredients to obtain roasted sand;

(2) leaching the calcine obtained in the step (1) by using an organic acid sodium solution, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

(3) converting and regenerating the leachate obtained in the step (2) by using organic acid ammonium, and performing solid-liquid separation after the conversion and regeneration are finished to obtain ammonium metavanadate solid and an organic acid sodium solution; recycling the obtained organic sodium solution in the step (2);

(4) separating the leaching residue obtained in the step (2) to obtain return residue, and reusing the return residue in the step (1);

the step (3) and the step (4) are not in sequence.

The specific implementation mode of the invention relates to detection and analysis of vanadium content in leachate and leaching residue, measurement of ammonium metavanadate purity and NH in solution₄ ⁺The detection and analysis of (3). The method for detecting the vanadium content in the leachate adopts YS/T540.1-2008 (part 1 of a vanadium chemical analysis method: a potassium permanganate-ferrous ammonium sulfate titration method for measuring the vanadium content); the content of vanadium in the leached slag is measured by GB/T6730.58-2017 (flame atomic absorption spectrometry for measuring the content of vanadium in iron ore); the purity analysis method of the ammonium metavanadate product adopts YS/T540.5-2008 (part 5 of the vanadium chemical analysis method: inductively coupled plasma atomic emission spectrometry for measuring impurity elements); NH in solution₄ ⁺The content determination method adopts GB/T34500.5-2007 (rare earth waste residue and wastewater chemical analysis method part 5: determination of ammonia nitrogen content).

The following are typical but non-limiting examples of the invention: