CN110735156A - method for preparing electrolyte containing low-valence titanium ions and method for extracting titanium by electrolysis - Google Patents

Abstract

The invention belongs to the technical field of rare metal refining, and discloses a method for preparing an electrolyte containing low-valent titanium ions. The method comprises the following steps: (1) uniformly mixing fluorotitanate and metal titanium powder, and pressing them into a green body (2) Melting one or more alkali metal halides and/or alkaline earth metal halide mixtures as matrix electrolyte; (3) Putting the green body into the matrix electrolyte for heat preservation treatment. The present invention also provides a method for electrolytically extracting titanium, the method comprising: preparing a mixed salt molten electrolyte according to the above method, and then performing electrolysis with the mixed salt molten electrolyte to obtain metallic titanium. The method of the present invention can avoid electrolyte pollution, introduce no other impurities, and can greatly improve the preparation efficiency.

Description

A method for preparing an electrolyte containing low-valent titanium ions and a method for electrolytically extracting titanium

technical field

The invention belongs to the technical field of rare metal refining, and in particular relates to a method for preparing an electrolyte containing low-valent titanium ions and a method for electrolytically extracting titanium, and more particularly, to a method for using fluorotitanate and metallic titanium powder to react to base melting A method for obtaining an electrolyte containing low-valent titanium ions by introducing Ti ²⁺ and Ti ³⁺ ions into an electrolyte, and a method for electrolytically extracting titanium by using the electrolyte.

Background technique

The electrolyte of molten salt electrolytic refining of titanium is usually an alkali metal or alkaline earth metal halide containing a certain amount of low-valent ions. Taking chloride molten salt as an example, the molten electrolyte is usually prepared by the following method: formulating an alkali metal or alkaline earth metal halide Or multiple mixtures are melted as the base electrolyte. The low-valent titanium ions in the electrolyte are usually prepared by reacting TiCl ₄ with sponge titanium in molten salt, which mainly includes the following reactions:

Ti+3TiCl ₄ =4TiCl ₃

Ti+TiCl ₄ =2TiCl ₂

TiCl ₂ +TiCl ₄ =2TiCl ₃

Ti+2TiCl ₃ =3TiCl ₂

Among them, TiCl ₄ is introduced into the sponge titanium preset in the reactor through the conduit, and reacts with it. At high temperature, TiCl ₄ gasifies into gas, which is very easy to corrode the conduit material and cause electrolyte pollution. In addition, TiCl ₄ is a hazardous chemical, which is prone to leakage and smoke accidents during use, which is extremely difficult to control. Furthermore, during preparation, since the above several reactions occur simultaneously, and the rate and extent of each reaction cannot be precisely controlled, the preparation efficiency is extremely low.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and to provide an electrolyte containing low-valent titanium ions by introducing Ti ²⁺ and Ti ³⁺ ions into the basic molten electrolyte by reacting fluorotitanate with metal titanium powder method, and use the electrolyte for electrolytic titanium extraction.

In order to achieve the above object, one aspect of the present invention provides a method for preparing an electrolyte containing low-valent titanium ions, the method comprising the following steps:

(1) Mixing fluorotitanate and metal titanium powder uniformly, and pressing into a green body;

(2) melting one or more alkali metal halide and/or alkaline earth metal halide mixture as matrix electrolyte;

(3) Putting the green body into the base electrolyte for heat preservation treatment.

Optionally, in step (1), the molar ratio of the fluorotitanate to the metal titanium powder is 1-3:1.

Optionally, the fluorotitanate is at least one of potassium fluorotitanate, sodium fluorotitanate, lithium fluorotitanate, magnesium fluorotitanate, calcium fluorotitanate, strontium fluorotitanate and barium fluorotitanate .

Optionally, in step (1), the implementation pressure of the pressing process is 5-40 MPa.

Optionally, in step (2), the alkali metal halide is an alkali metal fluoride and/or chloride, and the alkaline earth metal halide is an alkaline earth metal fluoride and/or chloride;

Preferably, the alkali metal fluoride is selected from one or more of lithium fluoride, sodium fluoride and potassium fluoride; the alkali metal chloride is selected from lithium chloride, sodium chloride and chloride One or more of potassium; the fluoride of the alkaline earth metal is selected from one or more of magnesium fluoride, barium fluoride and calcium fluoride; the chloride of the alkaline earth metal is selected from magnesium chloride, One or more of calcium, strontium chloride and barium chloride.

Optionally, in step (2), a mixture of at least two alkali metal chlorides is melted as a matrix electrolyte;

Preferably, the mixture of the chlorides of the at least two alkali metals is a mixture of potassium chloride and sodium chloride or lithium chloride;

Further preferably, in the mixture of the at least two alkali metal chlorides, the mass ratio of potassium chloride to sodium chloride or lithium chloride is 1.2-1.8:1.

Optionally, in step (3), the weight ratio of the base electrolyte to the green body is 4-66:1.

Optionally, in step (3), the temperature of the heat preservation treatment is 450-950°C.

A second aspect of the present invention provides a method for electrolytically extracting titanium, the method comprising: preparing a mixed salt molten electrolyte according to the above method, and then performing electrolysis with the mixed salt molten electrolyte to obtain metallic titanium.

Optionally, the electrolysis process is carried out in an electrolytic cell, and the anode of the electrolytic cell is titanium sponge or titanium oxycarbide, and the cathode is a carbon steel rod.

The beneficial effects of the method of the present invention are as follows: first, the use of _TiCl4 to corrode the reactor material is avoided to cause electrolyte pollution, and other impurities will not be introduced; secondly, the chemical property of fluorotitanate is more stable than that of _TiCl4 , and the operation is simple and easy to implement; Furthermore, the preparation time of low-valent Ti ions is reduced from 20-30 min/kg using TiCl ₄ to 8-10 min/kg, and the preparation efficiency is greatly improved.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The endpoints of the ranges disclosed herein and any values are not limited to the precise ranges or values, which are to be understood to include values near those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

The method for preparing an electrolyte containing low-valent titanium ions according to the present invention comprises the following steps:

(1) Mixing fluorotitanate and metal titanium powder uniformly, and pressing into a green body;

(2) melting one or more alkali metal halide and/or alkaline earth metal halide mixture as matrix electrolyte;

(3) Putting the green body into the base electrolyte for heat preservation treatment.

In step (1), in order to make the finally obtained low-valent titanium ion be Ti ²⁺ or Ti ³⁺ or their mixture, the molar ratio of the fluorotitanate to the metal titanium powder is preferably controlled to be 1-3 : 1, specifically, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1 or 3:1.

In the method of the present invention, the fluorotitanate can be a conventional choice in the art. In a preferred case, the fluorotitanate is at least one of potassium fluorotitanate, sodium fluorotitanate, lithium fluorotitanate, magnesium fluorotitanate, calcium fluorotitanate, strontium fluorotitanate and barium fluorotitanate kind. Most preferably, the fluorotitanate is potassium fluorotitanate.

In step (1), the mixing process of the fluorotitanate and the metal titanium powder is preferably implemented in a ball mill. The mixing time can be 0.1-2h, preferably 0.5-1h.

In step (1), the implementation pressure of the pressing process may be 5-40 MPa, preferably 10-30 MPa, and most preferably 15-25 MPa. By controlling the pressing pressure within the above-mentioned range, on the one hand, the reaction between the fluorotitanate and the metallic titanium powder is favorable, and on the other hand, it is also favorable for the diffusion of the reacted Ti ions.

In the method of the present invention, the alkali metal halide may be an alkali metal fluoride and/or chloride, and the alkaline earth metal halide may be an alkaline earth metal fluoride and/or chloride. The alkali metal fluoride may be one or more selected from lithium fluoride, sodium fluoride and potassium fluoride. The alkali metal chloride can be one or more selected from lithium chloride, sodium chloride and potassium chloride. The alkaline earth metal fluoride may be one or more selected from magnesium fluoride, barium fluoride and calcium fluoride. The chloride of the alkaline earth metal may be one or more selected from magnesium chloride, calcium chloride, strontium chloride and barium chloride.

In a more preferred embodiment, in step (2), the mixture of at least two alkali metal chlorides is melted and used as the base electrolyte. Further preferably, the mixture of the chlorides of the at least two alkali metals is a mixture of potassium chloride and sodium chloride or lithium chloride. Specifically, in one embodiment, the mixture of potassium chloride and sodium chloride is melted and used as the base electrolyte; in another embodiment, the mixture of potassium chloride and lithium chloride is melted and used as the base electrolyte. Further preferably, in the mixture of the chlorides of the at least two alkali metals, the mass ratio of potassium chloride to sodium chloride or lithium chloride is 1.2-1.8:1, preferably 1.25-1.75:1, more It is preferably 1.3-1.5:1.

In step (3), the weight ratio of the base electrolyte to the green body may be 4-66:1, specifically, for example, may be 4:1, 5:1, 6:1, 8:1, 10 :1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 62:1, 64:1 , 65:1 or 66:1. Preferably, the weight ratio of the base electrolyte to the green body may be 20-40:1.

In step (3), the temperature of the heat preservation treatment can be 450-950°C, preferably 500-750°C.

The present invention also provides a method for electrolytically extracting titanium, the method comprising: preparing a mixed salt molten electrolyte according to the above method, and then performing electrolysis with the mixed salt molten electrolyte to obtain metallic titanium.

In a specific implementation method, the electrolysis process is carried out in an electrolytic cell, and the anode of the electrolytic cell can be a titanium-containing material, such as titanium sponge or titanium oxycarbide, and the cathode is a metal material, such as a carbon steel rod. The specific action process is as follows: the anode Ti enters the electrolyte in the form of ions, and the titanium ions in the electrolyte are deposited at the cathode to obtain metallic titanium, while the total amount of Ti ions in the electrolyte remains unchanged.

The present invention will be described in detail through the following examples, but the protection scope of the present invention is not limited thereto.

Example 1

Weigh 2400 g of potassium fluorotitanate and 480 g of titanium powder (molar ratio 1:1) and mix them in a ball mill for 0.5 h.

The dried 83kg sodium chloride and 106kg potassium chloride were mixed uniformly, and melted under the protection of inert gas in a closed electrolytic cell to obtain a matrix molten salt.

The above-mentioned preformed body was put into NaCl-KCl matrix molten salt and kept at 950°C for 10 minutes. After completion, sampling was carried out for chemical analysis to obtain that the content of Ti ²⁺ and Ti ³⁺ ions in the mixed salt molten electrolyte was 0.47%.

Using the mixed salt as the electrolyte, the sponge titanium as the anode, and the carbon steel rod as the cathode, an electrolytic cell is formed for electrolysis to obtain metallic titanium with a purity of more than 99.5%.

Example 2

7200 g of potassium fluorotitanate and 480 g of titanium powder (molar ratio 3:1) were weighed and mixed in a ball mill for 0.5 h. After mixing evenly, a green body was formed with a pressure of 40 MPa.

11.15kg of dried lithium chloride and 19.57kg of potassium chloride were mixed uniformly, and melted under the protection of inert gas in a closed electrolytic cell to obtain a matrix molten salt.

The above preformed body was put into NaLi-KCl matrix molten salt and kept at 950°C for 15min. After completion, sampling was carried out for chemical analysis to obtain that the content of Ti ²⁺ and Ti ³⁺ ions in the mixed salt molten electrolyte was 5.1%.

Using the mixed salt as an electrolyte, titanium oxycarbide (Ti ₂ CO) as an anode, and a carbon steel rod as a cathode, an electrolytic cell is formed for electrolysis to obtain metallic titanium with a purity of more than 99.5%.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. A method for producing an electrolyte containing low valent titanium ions, characterized in that the method comprises the steps of:

   (1) mixing fluotitanate and metallic titanium powder uniformly, and pressing into a blank;

   (2) or a mixture of a plurality of alkali metal halides and/or alkaline earth metal halides are used as matrix electrolyte after being melted;

   (3) and putting the blank into the matrix electrolyte for heat preservation treatment.
2. 2. The method according to claim 1, wherein in the step (1), the molar ratio of the fluorotitanate to the metallic titanium powder is 1-3: 1.
3. 3. the method according to claim 1 or 2, wherein the fluorotitanate is at least of potassium fluorotitanate, sodium fluorotitanate, fluorolithium titanate, magnesium fluorotitanate, calcium fluorotitanate, strontium fluorotitanate, and barium fluorotitanate.
4. 4. The method according to claim 1 or 2, wherein in step (1), the pressing process is performed at a pressure of 5 to 40 MPa.
5. 5. The method according to claim 1, wherein in step (2), the alkali metal halide is a fluoride and/or chloride of an alkali metal, and the alkaline earth metal halide is a fluoride and/or chloride of an alkaline earth metal;

   preferably, the fluoride of the alkali metal is or more selected from lithium fluoride, sodium fluoride and potassium fluoride, the chloride of the alkali metal is or more selected from lithium chloride, sodium chloride and potassium chloride, the fluoride of the alkaline earth metal is or more selected from magnesium fluoride, barium fluoride and calcium fluoride, and the chloride of the alkaline earth metal is or more selected from magnesium chloride, calcium chloride, strontium chloride and barium chloride.
6. 6. The method according to claim 5, wherein in the step (2), a mixture of chlorides of at least two alkali metals is melted as a matrix electrolyte;

   preferably, the mixture of chlorides of at least two alkali metals is a mixture of potassium chloride and sodium chloride or lithium chloride;

   preferably, the mass ratio of potassium chloride to sodium chloride or lithium chloride in the mixture of the chlorides of at least two alkali metals is 1.2-1.8: 1.
7. 7. The method of claim 1, wherein in step (3), the weight ratio of the matrix electrolyte to the green body is from 4 to 66: 1.
8. 8. the method as claimed in claim 1, wherein the temperature of the heat-preserving treatment in the step (3) is 450-950 ℃.
9. 9. A method for electrolytically extracting titanium, which comprises preparing a mixed salt molten electrolyte according to the method of any of claims 1 to 8, and then performing electrolysis using the mixed salt molten electrolyte to obtain metallic titanium.
10. 10. The method of claim 9, wherein the electrolysis process is carried out in an electrolytic cell having an anode of titanium sponge or titanium oxycarbide and a cathode of carbon steel rod.