阅读说明：本技术 一种水热法从含钒草酸浸出母液中沉钒的方法 (Method for precipitating vanadium from vanadium-containing oxalic acid leaching mother liquor by hydrothermal method ) 是由 闫柏军 陈学鑫 于 2019-10-16 设计创作，主要内容包括：本发明提供一种从含钒草酸浸出母液中沉淀钒的方法。所用含钒草酸浸出母液为将钒铁尖晶石型含钒矿物,铁粉和草酸混合后加水形成料浆,经水热原位络合浸出,过滤后得到的含钒浸出液。该含钒浸出液无需浓缩及净化,直接加入到反应釜内,在180℃～250℃温度范围内,水热时间1h～5h条件下进行水热沉淀反应；反应后的浆体进行固液分离,将固体真空干燥后得到草酸亚钒(VC<Sub>2</Sub>O<Sub>4</Sub>·2H<Sub>2</Sub>O)。该方法利用草酸根离子在水热条件下分解成CO,CO<Sub>2</Sub>气体,在密闭空间形成还原条件,将溶液中的钒从+3价还原成+2价,从而与草酸根反应形成沉淀,达到沉钒的目的。本发明提供的沉钒方法条件温和,工艺简单,无需铵盐作为沉钒剂,并无氨氮废水及废气的产生；且沉钒产物为新型钒产品,具有绿色环保、节能减排等特点。(The invention provides a method for precipitating vanadium from oxalic acid leaching mother liquor containing vanadium. The vanadium-containing oxalic acid leaching mother liquor is prepared by mixing vanadium-iron spinel type vanadium-containing minerals, iron powder and oxalic acid, adding water to form slurry, performing hydrothermal in-situ complexing leaching, and filtering to obtain vanadium-containing leaching liquor. The vanadium-containing leaching solution is directly added into a reaction kettle without concentration and purification, and hydrothermal precipitation reaction is carried out at the temperature of 180-250 ℃ and the hydrothermal time of 1-5 h; carrying out solid-liquid separation on the slurry after reaction, and drying the solid in vacuum to obtain vanadyl oxalate (VC) 2 O 4 ·2H 2 O). The method utilizes oxalate ions to decompose into CO and CO under hydrothermal conditions 2 Gas forms reducing conditions in the closed space to reduce vanadium in the solution from +3 to +2, so that the vanadium reacts with oxalate to form precipitateThe purpose of vanadium precipitation is achieved. The vanadium precipitation method provided by the invention has mild conditions and simple process, does not need ammonium salt as a vanadium precipitation agent, and does not generate ammonia nitrogen wastewater and waste gas; and the vanadium precipitation product is a novel vanadium product, and has the characteristics of environmental protection, energy conservation, emission reduction and the like.)

1. A method for precipitating vanadium from oxalic acid leaching mother liquor containing vanadium by a hydrothermal method is characterized by comprising the following steps:

(1) mixing a mixture of vanadium-iron spinel vanadium-containing minerals and iron powder with oxalic acid, adding water to form slurry, reacting under a pressurized condition, and after the reaction is finished, carrying out solid-liquid separation to obtain vanadium-containing leachate;

(2) concentrating and purifying the vanadium-containing leaching solution obtained after the reaction in the step (1), pouring the vanadium-containing leaching solution into a reaction kettle, and carrying out hydrothermal reduction vanadium precipitation reaction under a hydrothermal condition;

(3) after the reaction in the step (2) is finished, carrying out solid-liquid separation, and carrying out vacuum drying on the solid to obtain vanadyl oxalate solid (VC)₂O₄·2H₂O)。

2. The method according to claim 1, wherein the concentration of vanadium in the vanadium-containing leachate obtained in the step (1) is 0.7-3 g/L, and the valence of the vanadium is + 3.

3. The hydrothermal process for precipitating vanadium from vanadiferous oxalic acid leaching mother liquor according to claim 1, wherein the concentration of impurity elements in the vanadium-containing leaching solution of step (1) is: fe <0.1 g/L; al <0.097 g/L; si <0.051 g/L; k <0.095 g/L; cr <0.06 g/L.

4. The hydrothermal method for precipitating vanadium from vanadium-containing oxalic acid leaching mother liquor according to claim 1, wherein the reaction temperature in the step (2) is 180-250 ℃; the reaction pressure is 1-5 Mpa, the reaction time is 1-5 h, and the reaction stirring speed is 500 rpm.

5. The hydrothermal method for precipitating vanadium from vanadiferous oxalic acid leaching mother liquor according to claim 1, wherein after the reaction in the step (2) is finished, the slurry is obtained by natural cooling, and then solid-liquid separation is carried out.

6. The hydrothermal method for precipitating vanadium from vanadiferous oxalic acid leaching mother liquor as claimed in claim 1, wherein the temperature of vacuum drying in step (3) is 50-70 ℃, and the vacuum degree is 0.08-0.1 Mpa.

Technical Field

The invention belongs to the field of vanadium precipitation from vanadium-containing leachate by a hydrothermal method. In particular to a method for reducing vanadium with valence +3 in vanadium-containing leaching solution into vanadium with valence +2 by using hydrothermal reduction to generate vanadyl oxalate (VC)₂O₄·2H₂O) precipitation.

Background

At present, two main vanadium-containing resources, namely vanadium titano-magnetite and vanadium-containing shale, can be converted into vanadium-containing minerals with a vanadium-iron spinel phase by a metallurgical method. The further extraction process of vanadium from vanadium-containing minerals with vanadium-iron spinel structure mainly includes sodium roasting, water leaching, purification and enrichment, vanadium precipitation and calcination. In the process link of vanadium precipitation of the vanadium-rich solution, the main method is hydrolysis vanadium precipitation and ammonium salt vanadium precipitation.

Chinese patent 201510416342.6 provides a novel method for preparing vanadium pentoxide by ammonium-free vanadium precipitation, wherein the pH is adjusted by sulfuric acid or sodium carbonate, and poly-vanadate precipitate is obtained by hydrolysis. However, the hydrolytic precipitation of vanadium is related to the nature of the vanadium bath, the content of impurities, the concentration, the temperature and the pH. When the sodium ion content in the solution is higher, obtaining sodium poly-vanadate; in addition, when the vanadium-rich solution contains high content of impurity elements such as iron, silicon, phosphorus, chlorine, etc., the hydrolysis process of vanadium and the purity of the final vanadium product are affected. In addition, in the process of hydrolyzing and precipitating vanadium, the pH value of the solution is an important factor influencing vanadium precipitation, the pH value needs to be controlled within a certain range, and when the pH value of the solution is too low, the hydrolysis precipitate can be dissolved, so that the yield of vanadium is finally influenced.

Therefore, in order to solve the problems caused by hydrolysis vanadium precipitation, metallurgists propose a method for precipitating vanadium by using ammonium salt, ammonium polyvanadate is obtained by adding ammonium salt, and a vanadium pentoxide product is obtained by calcining. The method has the advantages that the PH range of the solution is wide and is easy to control; in addition, ammonium ions and dodecavanadate are preferentially combined, so that the generation of sodium polyvanadate is avoided. Has the characteristics of high purity, less impurities, high precipitation rate and the like. However, ammonia nitrogen wastewater and waste gas generated in the process of depositing vanadium in ammonium salt seriously affect the environment and do not meet the requirements of environmental protection.

Chinese patent CN108642271A proposes a novel method for producing vanadium dioxide from vanadium-containing shale without ammonium, oxalic acid or oxalate is added into a vanadium-rich solution to be used as a reducing agent, vanadium in the solution is reduced from +5 to +4, and a vanadium dioxide product is obtained through a hydrothermal reaction one-step method. Calcination is not needed, and ammonia nitrogen wastewater and waste gas are not generated in the whole process. However, in the process, acid liquor or alkali liquor is needed to adjust the pH value of the solution to be between 0.7 and 0.9, and the pH range is narrow; in addition, the molar ratio of the oxalate to the vanadium is within the range of 1.0-2.0, so that the conditions are harsh, difficult to control and difficult to industrialize; in addition, the hydrothermal temperature is 180-250 ℃, the reaction lasts for 6-10 hours, and the energy consumption is large.

In order to solve the problems, a brand new vanadium extraction metallurgical route is proposed in response to the national requirements of energy conservation, emission reduction and environmental protection, vanadium-containing shale, ferric oxide powder and carbon powder are uniformly mixed according to a certain proportion and then roasted to obtain a vanadium-rich ferrovanadium spinel phase by a method mentioned in Chinese patent application numbers CN106011456A and CN107641723A, and vanadium-containing minerals of the ferrovanadium spinel phase are obtained by magnetic separation. Mixing vanadium-iron spinel type vanadium-containing minerals, iron powder and oxalic acid, adding water to form slurry, carrying out hydrothermal in-situ complexing leaching to obtain vanadium-containing leachate, and forming ferrous oxalate precipitate by iron impurities in the leachate under the action of a reducing agent iron powder; in addition, impurities such as Ca, Mg and the like in the leaching solution also form precipitates with oxalate; therefore, the obtained vanadium-containing leaching solution is relatively clean and does not need concentration and purification in the subsequent vanadium precipitation process. And (3) reducing the vanadium in the vanadium-containing leaching solution from the valence +3 to the valence +2 under the hydrothermal reduction condition, and forming a precipitate with oxalate, so that the vanadium is stripped from the solution, and the effect of vanadium precipitation is achieved.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for precipitating vanadium from vanadium-containing oxalic acid leaching mother liquor by a hydrothermal method. The method aims at vanadium-containing oxalic acid leaching mother liquor, vanadium-iron spinel vanadium-containing minerals, iron powder and oxalic acid are mixed according to a certain proportion and then added with water to form slurry, and vanadium obtained under the hydrothermal condition is trivalent vanadium-containing leaching liquor. The vanadium precipitation method comprises the following steps of putting oxalic acid leaching solution containing vanadium into a reaction kettle, reducing vanadium with a valence of 3 in the solution into vanadium with a valence of 2 under a certain hydrothermal reduction condition, and forming vanadyl oxalate precipitate with oxalate to achieve the effect of vanadium precipitation. Compared with the existing hydrolysis vanadium precipitation and ammonium salt vanadium precipitation, the vanadium precipitation condition is mild, the process is simple, no ammonia nitrogen wastewater and waste gas are generated, and the requirements of environmental protection are met.

A method for precipitating vanadium from oxalic acid leaching mother liquor containing vanadium by a hydrothermal method is characterized by comprising the following steps:

(1) mixing a mixture of vanadium-iron spinel vanadium-containing minerals and iron powder with oxalic acid, adding water to form slurry, reacting under a pressurized condition, and after the reaction is finished, carrying out solid-liquid separation to obtain vanadium-containing leachate;

(2) concentrating and purifying the vanadium-containing leaching solution obtained after the reaction in the step (1), pouring the vanadium-containing leaching solution into a reaction kettle, and carrying out hydrothermal reduction vanadium precipitation reaction under a hydrothermal condition;

(3) after the reaction in the step (2) is finished, carrying out solid-liquid separation, and carrying out vacuum drying on the solid to obtain vanadyl oxalate solid (VC)₂O₄·2H₂O)。

Further, the concentration of vanadium in the vanadium-containing leaching solution in the step (1) is 0.7-3 g/L, and the valence state of the vanadium is + 3.

Further, the concentration of impurity elements in the vanadium-containing leaching solution in the step (1) is as follows: fe <0.1 g/L;

Al<0.097g/L；Si<0.051g/L；K<0.095g/L；Cr<0.06g/L。

further, the reaction temperature in the step (2) is 180-250 ℃; the reaction pressure is 1-5 Mpa, the reaction time is 1-5 h, and the reaction stirring speed is 500 rpm.

Further, after the reaction in the step (2) is finished, naturally cooling to obtain slurry, and then carrying out solid-liquid separation.

Further, the temperature of vacuum drying in the step (3) is 50-70 ℃, and the vacuum degree is 0.08-0.1 Mpa.

The specific process of the invention is as follows:

the concentration of vanadium in the vanadium-containing leaching solution in the step (1) is 0.7-3 g/L, and the valence state of the vanadium is + 3; in addition, the concentration of impurity elements in the vanadium-containing leaching solution is as follows: fe <0.1 g/L; al <0.097 g/L; si <0.051 g/L; k <0.095 g/L; cr <0.06 g/L.

Putting the vanadium-containing leaching solution into a reaction kettle, wherein the filling degree of the vanadium-containing leaching solution is less than 50%;

the reaction temperature in the step (2) is 180-250 ℃, the reaction pressure is 1-5 Mpa, the reaction time is 1-5 h, and the reaction stirring speed is 500 rpm;

the following reaction may occur during the reaction in step (2):

2H₃[V(C₂O₄)₃]+H₂O→2VC₂O₄·2H₂O↓+5CO₂+3CO

and (3) after the reaction in the step (2) is finished, naturally cooling to obtain slurry, and then carrying out solid-liquid separation.

The temperature of vacuum drying in the step (3) is 50-70 ℃, and the vacuum degree is 0.08-0.1 Mpa.

Compared with the prior art, the technical scheme adopted by the invention has the following advantages:

1. the invention provides a method for precipitating vanadium from oxalic acid leaching mother liquor containing vanadium by a hydrothermal method, which utilizes CO and CO generated by hydrothermal decomposition₂And gas is used for reducing vanadium in the oxalic acid leaching mother liquor containing vanadium from +3 to +2 to form precipitate, so that the effect of vanadium precipitation is achieved.

2. The vanadia oxalate obtained by the method can be used as a good intermediate product for producing other divalent vanadium products.

3. Compared with the traditional hydrolysis vanadium precipitation and ammonium salt vanadium precipitation, the method has the advantages of mild vanadium precipitation conditions, simple working procedures, no generation of ammonia nitrogen wastewater and waste gas, and better accordance with the requirements of environmental protection.

Drawings

FIG. 1 is a process diagram of the vanadium precipitation according to the present invention.

Detailed Description

In order to verify the feasibility of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples. All such modifications made in accordance with the spirit of the present invention are intended to be included within the scope of the present invention.