阅读说明：本技术 采用硫酸钙焙烧钒渣的方法 (Method for roasting vanadium slag by adopting calcium sulfate ) 是由 顾武安 韩子柯 王烨 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种采用硫酸钙焙烧钒渣的方法,属于钒提取技术领域,包括以下步骤：将钒渣与钙化剂混匀后制成球团,焙烧,得到焙烧熟料,将焙烧熟料粉碎后置于酸液中浸出,固液分离得浸出液；所述钙化剂为含硫酸钙的物质。相比普通的钙化剂CaO和CaCO<Sub>3</Sub>,本发明使用硫酸钙作为钙化剂提钒,可利用红石膏作为原材料,不仅成本低,同时可以回收利用其中高含量的铁(约10wt％),还有助于缓解红石膏堆积问题,而且钒的浸出率最大可以达到95.6％,高于传统钙化剂,同时还可以回收钒渣和红石膏中90.1％的铁,并将红石膏中的硫用于浸出焙烧熟料酸液中。(The invention discloses a method for roasting vanadium slag by adopting calcium sulfate, belonging to the technical field of vanadium extraction and comprising the following steps of: uniformly mixing vanadium slag and a calcification agent to prepare pellets, roasting to obtain roasted clinker, crushing the roasted clinker, then leaching in acid liquor, and carrying out solid-liquid separation to obtain a leaching solution; the calcification agent is a calcium sulfate-containing substance. Compared with common calcification agents CaO and CaCO 3 The calcium sulfate is used as the calcification agent to extract vanadium, the red gypsum is used as a raw material, the cost is low, high-content iron (about 10 wt%) in the red gypsum can be recycled, the problem of red gypsum accumulation can be relieved, the leaching rate of the vanadium can reach 95.6% to the maximum extent, the leaching rate is higher than that of the traditional calcification agent, 90.1% of iron in the vanadium slag and the red gypsum can be recycled, and sulfur in the red gypsum is used for leaching the acid liquor of roasting clinker.)

1. The method for roasting vanadium slag by adopting calcium sulfate is characterized by comprising the following steps of:

uniformly mixing vanadium slag and a calcification agent to prepare pellets, roasting to obtain roasted clinker, crushing the roasted clinker, then leaching in acid liquor, and carrying out solid-liquid separation to obtain a leaching solution; the calcification agent is a calcium sulfate-containing substance.

2. The method for roasting vanadium slag by using calcium sulfate according to claim 1, which is characterized in that: the ratio of the calcification agent to the vanadium slag is 1 in terms of the molar ratio of Ca to V: 1.

3. the method for roasting vanadium slag by using calcium sulfate according to claim 1, which is characterized in that: the roasting temperature is 1200-1300 ℃; preferably, the temperature of the calcination is 1250 ℃.

4. The method for roasting vanadium slag by using calcium sulfate according to claim 1, which is characterized in that: the roasting time is 2-3 h; preferably for 2 hours.

5. The method for roasting vanadium slag by using calcium sulfate according to claim 1, which is characterized in that: the vanadium slag is obtained by blowing vanadium-containing pig iron in a converter, and is crushed to 150-200 meshes before use; the calcification agent is calcium sulfate or red gypsum.

6. The method for roasting vanadium slag by using calcium sulfate according to claim 5, wherein the red gypsum is waste generated in the preparation of titanium dioxide by using a sulfuric acid method; preferably, the red gypsum contains the following components: fe₂O₃ 8～11wt％、CaSO₄·2H₂O 83～85wt％、MgO 1.5～3wt％、SiO₂ 0.5～1wt％、CaO 3～4wt％、Al₂O₃ 0.5～1wt％。

7. The method for roasting vanadium slag by using calcium sulfate according to claim 1, which is characterized in that: the acid solution is a sulfuric acid solution with the mass fraction of 10-15%.

8. The method for roasting vanadium slag by using calcium sulfate according to claim 7, characterized in that: the leaching temperature is 65 ℃; the leaching time is 80-100 min.

9. The method for roasting vanadium slag by using calcium sulfate according to claim 1, further comprising the following steps of: by NH₃Adjusting the pH value of the leaching solution to 2.1 +/-0.2, adding ammonium sulfate to precipitate vanadium, carrying out solid-liquid separation, and calcining the solid to obtain V₂O₅And NH₃Liquid passing through NH₃And adjusting the pH value to 4-5, precipitating iron, carrying out solid-liquid separation, and calcining the solid to obtain iron oxide.

10. The method for roasting vanadium slag by using calcium sulfate according to claim 9, wherein the method comprises the following steps: the ratio of the ammonium sulfate to the vanadium in the leaching solution is the ammonium sulfate to the V₂O₅The molar ratio of (a) is 0.3-0.9: 1; preferably 0.9: 1.

Technical Field

The invention belongs to the technical field of vanadium extraction, and particularly relates to a method for roasting vanadium slag by adopting calcium sulfate.

Background

The rare metal vanadium is an important strategic material and is mainly applied to the fields of steel industry, national defense advanced technology, chemical industry, light textile industry and the like. The vanadium resources in the world are rich and widely distributed, but no rich ore which can be independently exploited exists, andis symbiotic with other minerals at low grade. Vanadium titano-magnetite is already the major source of vanadium production in the world today. In China, the direct vanadium extraction raw material currently used in practical production is vanadium slag obtained by converting vanadium-containing pig iron. The traditional method for converting vanadium in vanadium slag into water-soluble vanadium is sodium oxide roasting-water leaching vanadium. However, the method has the disadvantages of high energy consumption, low efficiency and large amount of HCl and Cl discharged in the production process₂And toxic gases and wastewater containing high-concentration sodium chloride cause serious environmental pollution and the like. In addition, the sodium roasting vanadium extraction technology is not suitable for high-calcium vanadium slag. In recent years, the demand for vanadium has been gradually rising with the rapid increase in the production of steel in china. Therefore, on the basis of the traditional vanadium extraction method, research and exploration of a novel vanadium extraction process with short flow, low cost and no pollution are urgent, and the method is also the development direction of a novel future vanadium extraction technology.

Disclosure of Invention

The invention aims to provide a low-cost vanadium extraction process.

The invention provides a method for roasting vanadium slag by adopting calcium sulfate, which comprises the following steps:

uniformly mixing vanadium slag and a calcification agent to prepare pellets, roasting to obtain roasted clinker, crushing the roasted clinker, then leaching in acid liquor, and carrying out solid-liquid separation to obtain a leaching solution; the calcification agent is a calcium sulfate-containing substance.

According to the method for roasting vanadium slag by adopting calcium sulfate, the ratio of the calcification agent to the vanadium slag is 1: 1.

the method for roasting vanadium slag by adopting calcium sulfate is characterized in that the roasting temperature is 1200-1300 ℃; preferably, the temperature of the calcination is 1250 ℃.

According to the method for roasting vanadium slag by adopting calcium sulfate, the roasting time is 2-3 h; preferably for 2 hours.

In the method for roasting vanadium slag by adopting calcium sulfate, the vanadium slag is obtained by converting vanadium-containing pig iron through a converter, and the vanadium slag is crushed to 150-200 meshes before use; the calcification agent is calcium sulfate or red gypsum.

In the method for roasting vanadium slag by adopting calcium sulfate, the red gypsum is waste generated by preparing titanium dioxide by a sulfuric acid method; preferably, the red gypsum contains the following components: fe₂O₃ 8～11wt％、CaSO₄·2H₂O 83～85wt％、MgO 1.5～3wt％、SiO₂ 0.5～1wt％、CaO 3～4wt％、Al₂O₃ 0.5～1wt％。

In the method for roasting vanadium slag by adopting calcium sulfate, the acid solution is a sulfuric acid solution with the mass fraction of 10-15%.

Wherein, in the method for roasting vanadium slag by adopting calcium sulfate, the leaching temperature is 65 ℃; the leaching time is 80-100 min.

The method for roasting vanadium slag by adopting calcium sulfate further comprises the following steps: by NH₃Adjusting the pH value of the leaching solution to 2.1 +/-0.2, adding ammonium sulfate to precipitate vanadium, carrying out solid-liquid separation, and calcining the solid to obtain V₂O₅And NH₃Liquid passing through NH₃And adjusting the pH value to 4-5, precipitating iron, carrying out solid-liquid separation, and calcining the solid to obtain iron oxide.

In the method for roasting vanadium slag by adopting calcium sulfate, the ratio of ammonium sulfate to vanadium in the leaching solution is ammonium sulfate and V₂O₅The molar ratio of (a) is 0.3-0.9: 1; preferably 0.9: 1.

the invention has the beneficial effects that:

compared with common calcification agents CaO and CaCO₃The calcium sulfate is used as the calcification agent to extract vanadium, the red gypsum is used as a raw material, the cost is low, high-content iron (about 10 wt%) in the red gypsum can be recycled, the problem of red gypsum accumulation can be relieved, the leaching rate of the vanadium can reach 95.6% to the maximum extent, the leaching rate is higher than that of the traditional calcification agent, 90.1% of iron in the vanadium slag and the red gypsum can be recycled, and sulfur in the red gypsum is used for leaching the acid liquor of roasting clinker.

Drawings

FIG. 1 shows vanadium slag-CaSO₄And (3) a standard free energy change diagram of the system calcification reaction.

Detailed Description

Specifically, the method for roasting vanadium slag by adopting calcium sulfate comprises the following steps:

uniformly mixing vanadium slag and a calcification agent to prepare pellets, roasting to obtain roasted clinker, crushing the roasted clinker, then leaching in acid liquor, and carrying out solid-liquid separation to obtain a leaching solution; the calcification agent is a calcium sulfate-containing substance.

Whatever calcification agent is used, the process is roughly divided into 3 processes: the tissue structure of the vanadium mineral is destroyed; oxidation of vanadium suboxides to form V₂O₅；V₂O₅Combined with calcifying agent to generate calcium vanadate XCaO.V₂O₅(X ═ 1,2,3), and all of these 3 substances are acid-soluble substances. CaSO₄The possible calcification reactions during the roasting in the case of the calcification agent are as follows:

2CaSO₄(s)+2V₂O₅(l)＝2CaV₂O₆(s)+2SO₂(g)+O₂(g) (1)

2CaSO₄(s)+V₂O₅(l)＝Ca₂V₂O₇(s)+2SO₂(g)+O₂(g) (2)

3CaSO₄(s)+V₂O₅(l)＝Ca₃V₂O₈(s)+3SO₂(g)+3/2O₂(g) (3)

2CaSO₄(s)+2Fe₂O₃(s)＝2CaFe₂O₄(s)+2SO₂(g)+O₂(g) (4)

2CaSO₄(s)+Fe₂O₃(s)＝Ca₂Fe₂O₅(s)+2SO₂(g)+O₂(g) (5)

vanadium slag-CaSO according to FIG. 1₄The standard free energy change diagram of the system calcification reaction shows that Ca is generated when the roasting temperature is higher than 1150 DEG C₂V₂O₇Starting generation; generation of CaV₂O₆The reaction temperature of (a) is higher than 1500 ℃; the temperature for generating calcium ferrite is above 1400 ℃.

To ensure that more Ca is generated₂V₂O₇Benshen (Benshen)Please limit the molar ratio of Ca to V in the calcification agent and vanadium slag to 1:1, when the addition amount of calcium sulfate is too small, vanadium oxide and other oxides in slag generate vanadate, such as ferric vanadate, manganese vanadate and the like, and the vanadium oxide is incompletely converted and has low leaching rate; the excessive calcium sulfate can be mixed with other acidic oxides in the vanadium slag, such as SiO₂Etc. to produce Ca₂SiO₄And the substances can wrap vanadium, so that the extraction of the vanadium is not facilitated, and meanwhile, a large amount of acid can be consumed in the acid leaching process of the generated calcium salts, and the recovery of the vanadium can be influenced.

To ensure that CaV is not generated₂O₆The reaction temperature is set to 1200-1300 ℃, if the reaction temperature is too high, the energy consumption is increased, and other substances can be generated; when the reaction temperature is too low, the calcium sulfate and the vanadium slag are difficult to react, and the reaction rate is slow. The invention sets the reaction temperature to 1250 ℃ by integrating the energy consumption and the extraction rate of vanadium and iron.

At the roasting temperature of the invention, calcium sulfate reacts with vanadium pentoxide to generate Ca₂V₂O₇Without reacting with the iron oxide. The sulfur dioxide generated by roasting can be recovered to prepare sulfuric acid for subsequent steps.

When the roasting time is less than 2h, the leaching rate of vanadium is increased along with the increase of the roasting time; when the roasting time is more than 2 hours, the leaching rate of the vanadium is not obviously improved. In consideration of vanadium leaching rate and cost, the roasting time is set to be 2-3 h; preferably for 2 hours.

In the method, the calcification agent is calcium sulfate or red gypsum. In the aspect of recovering vanadium, the vanadium extraction effect of calcium sulfate can be better than that of calcium oxide, but the cost of calcium sulfate is much lower than that of calcium oxide, and the calcium sulfate can be derived from solid waste red gypsum, and the red gypsum is used as a calcification agent, so that the problem of red gypsum accumulation can be solved.

In the method, the acidity of the acid liquor used in the acid leaching process is further increased, which is beneficial to leaching vanadium, but can cause more serious corrosion to equipment; the low acidity leads to a long and normal leaching time, and also reduces the concentration of vanadium in the leaching solution, which is not beneficial to vanadium precipitation. Therefore, the mass fraction of the acid liquor in the acid leaching process is set to be 10% -15%, the acid liquor is preferably a sulfuric acid solution, and a large amount of sulfur dioxide can be generated in the roasting process of calcium sulfate and vanadium slag, so that the sulfuric acid can be prepared, and the aim of recycling is fulfilled.

In the acid leaching process, calcium vanadate, ferric oxide and sulfuric acid react to generate calcium sulfate, vanadyl sulfate and ferric sulfate.

In the method, when the leaching temperature is lower than 65 ℃, the leaching rate of vanadium is increased along with the increase of the temperature, the leaching rate reaches the maximum at 65 ℃, then the temperature is continuously increased, the leaching rate of vanadium is not changed greatly, the leaching rates are all about 90 percent, and the higher the temperature is, the higher the energy consumption is, and the more serious the corrosion of equipment is. Therefore, the present invention sets the temperature of leaching to 65 ℃.

In the vanadium precipitation process of the invention, when ammonium sulfate and V are mixed₂O₅When the molar ratio of (a) to (b) is less than 0.3, the reaction time is prolonged to more than 1 hour; the time for precipitating vanadium is shorter as the ratio is increased, when the ammonium sulfate is mixed with V₂O₅When the molar ratio of (a) to (b) is 0.9, the vanadium precipitation can be finished only in 20 minutes (the vanadium concentration in the solution is less than 0.1g/L), and under a certain vanadium concentration, the purity of ammonium vanadate can be improved according to the increase of the addition amount of ammonium sulfate, which can be understood that the ammonium ion concentration is increased to facilitate the precipitation of ammonium salt, so that the precipitation of impurity elements is reduced.

In the process of the invention, NH formed by calcining ammonium vanadate₃Can be used for adjusting the pH value of the leaching solution in the next step, and can also be reacted with sulfuric acid to generate ammonium sulfate for the vanadium precipitation step, thereby achieving the purpose of recycling.

The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.

The red gypsum used in the following examples is waste generated in the preparation of titanium dioxide by a sulfuric acid method, and the specific components are as follows: fe₂O₃ 10.1wt％、CaSO₄·2H₂O 83.5wt％、MgO 1.8wt％、SiO₂ 0.7wt％、CaO 3.3wt％、Al₂O₃0.6 wt% and the vanadium slag components are shown in the following table: