阅读说明：本技术 钒溶液还原制备氧化钒的方法 (Method for preparing vanadium oxide by reducing vanadium solution ) 是由 付自碧 伍珍秀 蒋霖 饶玉忠 于 2020-07-06 设计创作，主要内容包括：本发明属于钒的湿法冶金技术领域,具体涉及一种钒溶液还原制备氧化钒的方法。本发明所要解决的技术问题是提供一种钒溶液还原制备氧化钒的方法,包括以下步骤：钒溶液除杂得到除杂后液,加热除杂后液至50～100℃,然后与三氧化二钒混合,加入有机酸调节体系pH为5～7进行反应,固液分离得到沉钒上清液和钒沉淀物,钒沉淀物经还原得到三氧化二钒。本发明方法选用的还原剂、pH调节试剂可循环使用,不引入杂质元素；上清液可直接循环使用,避免现有氧化钒生产过程中钒铬还原滤饼、含铵硫酸钠等固废的产生。(The invention belongs to the technical field of vanadium hydrometallurgy, and particularly relates to a method for preparing vanadium oxide by reducing a vanadium solution. The invention aims to solve the technical problem of providing a method for preparing vanadium oxide by reducing a vanadium solution, which comprises the following steps: removing impurities from a vanadium solution to obtain a solution after impurity removal, heating the solution after impurity removal to 50-100 ℃, mixing the solution with vanadium trioxide, adding an organic acid to adjust the pH of a system to be 5-7 for reaction, performing solid-liquid separation to obtain a vanadium precipitation supernatant and a vanadium precipitate, and reducing the vanadium precipitate to obtain vanadium trioxide. The reducing agent and the pH adjusting agent selected by the method can be recycled, and no impurity element is introduced; the supernatant can be directly recycled, and the generation of solid wastes such as vanadium-chromium reduction filter cakes, ammonium-containing sodium sulfate and the like in the existing production process of vanadium oxide is avoided.)

1. The method for preparing vanadium oxide by reducing vanadium solution is characterized by comprising the following steps: the method comprises the following steps: removing impurities from a vanadium solution to obtain a solution after impurity removal, heating the solution after impurity removal to 50-100 ℃, mixing the solution with vanadium trioxide, adding an organic acid to adjust the pH of a system to be 5-7 for reaction, performing solid-liquid separation to obtain a vanadium precipitation supernatant and a vanadium precipitate, and reducing the vanadium precipitate to obtain vanadium trioxide.

2. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: sodium aluminate is adopted for impurity removal; further, the dosage of the sodium aluminate is 0.6-2.0 of the molar ratio of Al to Si.

3. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: the dosage of the vanadium trioxide is calculated according to the molar ratio V³⁺/V⁵⁺The control is 0.9-1.0.

4. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: the organic acid is at least one of formic acid, oxalic acid, tartaric acid, ascorbic acid or carbonic acid.

5. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: the reaction time is 0.1-5 h.

6. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: the reduction adopts reducing gas; further, the reducing gas is at least one of hydrogen, carbon monoxide, blast furnace gas, coke oven gas or natural gas.

7. The method for preparing vanadium oxide by reducing vanadium solution according to claim 1, wherein: the reduction temperature is 700-900 ℃.

8. The method for preparing vanadium oxide by reducing vanadium solution according to any one of claims 1 to 7, wherein: the vanadium solution is obtained by calcifying and roasting vanadium slag to obtain roasted clinker, and the roasted clinker is obtained by leaching sodium-containing carbonate.

9. The method for preparing vanadium oxide by reducing vanadium solution according to claim 8, wherein: in the calcification roasting step, at least any one of the following conditions is satisfied:

the particle size of the vanadium slag is-0.096 mm;

the calcium salt for calcification roasting is at least one of calcium carbonate, calcium hydroxide or calcium oxide;

the amount of the calcium salt for calcification roasting is 0 to 8 percent of the mass of the vanadium slag by taking CaO as the weight;

the temperature of the calcification roasting is 800-950 ℃; the time is 40-200 min.

10. The method for preparing vanadium oxide by reducing vanadium solution according to claim 8, wherein: in the sodium carbonate leaching step, at least any one of the following is satisfied:

the sodium-containing carbonate is at least one of sodium carbonate or sodium bicarbonate; further, the sodium-containing carbonate is sodium bicarbonate;

the mass concentration of the sodium carbonate is 8-12%; the mass concentration of the sodium bicarbonate is 12-17%;

the sodium carbonate is added in an amount of CO₃ ^2-The molar weight of vanadium in the roasting clinker is 1.5-3.5 times;

the solid-to-solid ratio of the leaching solution is 1.8-3.0 mL:1 g;

the leaching temperature is 80-100 ℃; the leaching time is 30-150 min.

Technical Field

The invention belongs to the technical field of vanadium hydrometallurgy, and particularly relates to a method for preparing vanadium oxide by reducing a vanadium solution.

Background

The vanadium slag is a main raw material for preparing vanadium oxide, and the traditional production process is sodium roasting-water vanadium extraction. In the vanadium extraction process, the vanadium extraction tailings containing about 6 percent of sodium oxide can be generated, the vanadium extraction tailings are difficult to be reused, and a vanadium-chromium reduction filter cake and a large amount of solid waste sodium sulfate are difficult to treat, so that the environmental protection hidden danger is large; a large amount of sodium carbonate is consumed in the vanadium extraction process, and the process cost is high. In order to reduce the production cost of vanadium oxide and eliminate the hidden trouble of environmental protection, the process idea of preparing vanadium oxide by calcifying roasting-carbonating leaching of vanadium slag is provided.

The doctor academic paper of Chongqing university published by the newly-published plum publication discloses the research on the mechanism of roasting-leaching reaction process of high-calcium low-grade vanadium slag, wherein the concentration of sodium carbonate serving as a leaching agent used in the research on the roasting-leaching process of calcium sodium carbonate from vanadium slag is 160g/L, and the solid-to-solid ratio of a leaching solution is 10:1 (mL/g). The leaching solution obtained by the method has low vanadium concentration and high Na/V ratio, so that the vanadium precipitation rate is low when ammonium metavanadate is subsequently precipitated.

CN102560086A discloses a vanadium extraction method for leaching vanadium slag clinker with ammonium carbonate, which comprises leaching with 200-800 g/L ammonium carbonate solution and vanadium slag clinker at 60-98 ℃ according to a liquid-solid ratio of 5: 1-30: 1. The method has the advantages of high consumption of leaching agent and high production cost; in addition, because of the low solubility of ammonium metavanadate, in order to avoid vanadium from precipitating into residues in the form of ammonium metavanadate, the method needs to control a larger liquid-solid ratio when ammonium carbonate is used for leaching. Therefore, the vanadium concentration of the obtained leaching solution is low; on the other hand, the solubility of ammonium metavanadate is reduced along with the reduction of temperature, and the ammonium metavanadate is easily separated out when the temperature of the leaching solution is reduced by the method, so that the solution system is unstable.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing vanadium oxide by reducing a vanadium solution. The method comprises the following steps: removing impurities from a vanadium solution to obtain a solution after impurity removal, heating the solution after impurity removal to 50-100 ℃, mixing the solution with vanadium trioxide, adding an organic acid to adjust the pH of a system to be 5-7 for reaction, performing solid-liquid separation to obtain a vanadium precipitation supernatant and a vanadium precipitate, and reducing the vanadium precipitate to obtain vanadium trioxide.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, sodium aluminate is adopted for impurity removal.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the dosage of sodium aluminate is 0.6-2.0 of the molar ratio of Al/Si.

Specifically, in the method for preparing vanadium oxide by reducing vanadium solution, the vanadium trioxide is used in an amount V³⁺/V⁵⁺The molar ratio is controlled to be 0.9 to 1.0.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, the organic acid is at least one of formic acid, oxalic acid, tartaric acid, ascorbic acid or carbonic acid.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, the reaction time is 0.1-5 hours.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, reducing gas is used for the reduction.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the reducing gas is at least one of hydrogen, carbon monoxide, blast furnace gas, coke oven gas or natural gas.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, the reduction temperature is 700-900 ℃.

Specifically, in the method for preparing vanadium oxide by reducing the vanadium solution, the vanadium solution is obtained by calcifying and roasting vanadium slag to obtain roasted clinker, and the roasted clinker is obtained by leaching sodium-containing carbonate.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the granularity of the vanadium slag is-0.096 mm.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the calcium salt roasted by calcification is at least one of calcium carbonate, calcium hydroxide or calcium oxide.

Furthermore, in the method for preparing vanadium oxide by reducing the vanadium solution, the amount of the calcium salt for calcification roasting is 0-8% of the mass of the vanadium slag by taking CaO as a reference.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the calcification roasting temperature is 800-950 ℃.

The time is 40-200 min.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the sodium-containing carbonate is at least one of sodium carbonate or sodium bicarbonate. The mass concentration of the sodium carbonate is 8-12%. The mass concentration of the sodium bicarbonate is 12-17%.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the sodium-containing carbonate is sodium bicarbonate.

Furthermore, in the method for preparing vanadium oxide by reducing the vanadium solution, the sodium-containing carbonate is added according to the amount of CO₃ ^2-The molar weight of vanadium in the roasted clinker is 1.5-3.5 times.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the solid-to-solid ratio of the leaching solution is 1.8-3.0 mL:1 g.

Further, in the method for preparing vanadium oxide by reducing the vanadium solution, the leaching temperature is 80-100 ℃. The leaching time is 30-150 min.

According to the method, the vanadium is separated in a mode of adding pentavalent vanadium in a vanadium trioxide reduction system into the solution after impurity removal and adding an organic acid to adjust the pH of the system to precipitate tetravalent vanadium, so that the cyclic utilization of a reduction reagent is realized, and the introduction of impurity elements is avoided.

The method of the invention can not generate vanadium-chromium reduction filter cakes and solid waste sodium sulfate, and the obtained vanadium precipitation upper layer liquid can be returned to the leaching process to be used as a leaching agent for recycling, thereby realizing low-cost clean production of vanadium oxide by vanadium slag, reducing the consumption of the leaching agent, and solving the problems of high process cost and difficult utilization of the solid waste vanadium-chromium reduction filter cakes and sodium sulfate in the traditional vanadium slag sodium salt roasting-water leaching of vanadium.

Detailed Description

The method for preparing vanadium oxide by calcifying roasting, carbonating leaching and reducing of vanadium slag comprises the following steps:

a. mixing vanadium slag with the particle size of-0.096 mm and 0% -8% of calcium salt uniformly, and roasting at 800-950 ℃ for 40-200 min to obtain roasted clinker;

b. stirring and leaching the roasted clinker by using a sodium-containing carbonate solution at 80-100 ℃ for 30-150 min, and performing solid-liquid separation to obtain a leaching solution;

c. adding sodium aluminate into the leaching solution to remove impurities, and carrying out solid-liquid separation to obtain a solution after impurity removal;

d. preheating the solution after impurity removal to 50-100 ℃, adding the solution into a pressure reaction kettle filled with vanadium trioxide, simultaneously adding organic acid into the reaction kettle to adjust the pH value of the solution to 5-7, stirring and reacting for 0.1-5 h, and carrying out solid-liquid separation to obtain a vanadium precipitation supernatant and a vanadium precipitate;

e. d, preparing vanadium trioxide by using the vanadium precipitate through high-temperature reduction of reducing gas, returning part of vanadium trioxide to the step d for recycling, and using the rest vanadium trioxide as a vanadium product for smelting vanadium-containing alloy; the supernatant fluid of the precipitated vanadium is directly recycled for leaching clinker.

Further, in step a, the calcium salt is at least one of calcium carbonate, calcium hydroxide or calcium oxide.

Further, in step b, the sodium carbonate is used in an amount of CO₃ ^2-The molar weight of vanadium in the roasted clinker is 1.5-3.5 times.

Further, in step b, the sodium-containing carbonate is at least one of sodium carbonate or sodium bicarbonate. Sodium bicarbonate is preferred.

Further, in the step b, the solid-to-solid ratio of the leaching solution is controlled to be 1.8-3.0 mL:1 g.

Further, in the step c, the dosage of the sodium aluminate is 0.6-2.0 of the molar ratio of Al to Si (Si in the leaching solution).

Further, in step d, the vanadium trioxide is used in an amount V³⁺/V⁵⁺(V in the solution after removal of impurities⁵⁺) The molar ratio is controlled to be 0.9 to 1.0.

In the step d, the organic acid is one or more of formic acid, oxalic acid, tartaric acid, ascorbic acid or carbonic acid.

Further, in the step e, the reducing gas is one or more of hydrogen, carbon monoxide, blast furnace gas, coke oven gas or natural gas.

In the step a of the method, the adopted vanadium slag is common vanadium slag or high-calcium high-phosphorus vanadium slag obtained by oxidizing and blowing vanadium-containing molten iron. In order to fully expose the ferrovanadium spinel in the vanadium slag, facilitate the oxidation of the ferrovanadium spinel and the full contact reaction of the vanadium slag and calcium salt, crushing the vanadium slag, and selecting the vanadium slag with the granularity of less than 0.096 mm. Because the solubility of calcium metavanadate in water is larger than that of calcium pyrovanadate and calcium orthovanadate, the calcium metavanadate is beneficial to leaching, and in order to control the vanadium in the calcified roasting clinker to mainly exist in the form of calcium metavanadate, the amount of added calcium salt is 0-8 percent of the mass of the vanadium slag calculated by CaO.

In the step b of the method, the roasting clinker is leached by carbonate containing sodium, and the carbonation leaching is adopted because the solubility of calcium carbonate is lower than that of calcium metavanadate, calcium pyrovanadate and calcium n-vanadate, calcium ions and carbonate are combined into slag, and vanadium enters solution. The inventor controls the dosage of the sodium carbonate to be CO₃ ^2-the/V is 1.5-3.5 (mol ratio) to provide enough carbonate for leaching, and the leaching rate of vanadium is improved. In order to further obtain high-concentration vanadium-containing leachate, the solid-to-solid ratio of the leachate is controlled to be 1.8-3.0: 1 mL/g. In order to facilitate the dissolution of calcium metavanadate, the leaching temperature is controlled to be 80-100 ℃.

In step c of the method, the sodium aluminate is used for simultaneously removing silicon and phosphorus in the leaching solution.

In step d of the method, vanadium trioxide is added into the solution after impurity removal because pentavalent vanadium in the solution can be reduced into tetravalent vanadium under the weak acidic condition without introducing new impurities, and meanwhile trivalent vanadium is oxidized into tetravalent vanadium. Vanadium trioxide dosage V³⁺/V⁵⁺The molar ratio is 0.9-1.0 (mol ratio) to avoid the trivalent vanadium remaining in the supernatant liquid, and vanadium loss is caused in the process of leaching clinker by circulating the supernatant liquid. The pH value of the reaction slurry is controlled to be 5-7 because the pH value of the tetravalent vanadium precipitate is more than or equal to 4.2, and the tetravalent vanadium is fully precipitated in the form of vanadium hydroxide under the condition that the pH value is 5-7. The organic acid is chosen to adjust the pH of the slurry so that no new impurity elements are introduced and the bicarbonate formed by the reaction can be recycled with the process water in step b for leaching the clinker.

In the step d of the method, the temperature is high, so that the reaction speed and the reduction degree of trivalent vanadium and pentavalent vanadium are improved, and the solution after impurity removal is heated to 50-100 ℃.