US20130084206A1

US20130084206A1 - Method for production of metallic titanium and metallic titanium obtained with the method

Info

Publication number: US20130084206A1
Application number: US13/618,945
Authority: US
Inventors: Yuchang Zhou; Tianzhu Mu; Beilei Yan; Sanchao Zhao; Yangjun Yang
Original assignee: Pangang Group Co Ltd
Current assignee: Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd; Pangang Group Co Ltd
Priority date: 2011-09-30
Filing date: 2012-09-14
Publication date: 2013-04-04
Also published as: DE102012108564B4; CN103031577B; JP5526207B2; CN103031577A; DE102012108564A1; JP2013079446A

Abstract

A method for production of metallic titanium and metallic titanium obtained with the method are provided. The method for production of metallic titanium comprises: taking a titaniferous material as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions to obtain metallic titanium; wherein, the titaniferous material is in a porous structure, with 1 mm˜10 mm average pore diameter and 20%˜60% porosity, and at least a part of the titanium element in the titaniferous material exists in the form of TiO_x, wherein, 2>x>0. With the method provided in the present invention, the process is simplified, and the yield ratio and purity of the obtained metallic titanium are higher.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority to Chinese Application No. 201110293657.8, filed on Sep. 30, 2011, entitled “Method for Production of Metallic Titanium and Metallic Titanium Obtained with the Method”, which is specifically and entirely incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a method for production of metallic titanium and metallic titanium obtained with the method.

BACKGROUND OF THE INVENTION

Titanium and titanium alloys have advantages such as low density, high specific strength, high heat and cold resistance, high corrosion resistance, and outstanding biological compatibility, etc., and therefore are honored as “future metal”, “spatial metal”, and “marine metal”.
Titanium belongs to a sort of rare metal; however, actually the abundance of titanium element in the earth crust takes the seventh place (0.45 wt. %), much higher than the abundance of many common metals. Owing to the active nature of titanium, the requirements for the refining process are very strict, and therefore it is difficult to product titanium in a large quantity. Thus, titanium is classified as a “rare” metal material. At present, the only industrial production process of metallic titanium popular in the world is Kroll process, which comprises procedures mainly including: production of titanium chloride from titanium oxide, magnesium reduction-vacuum distillation, post-treatment of the product, and magnesium electrolysis, etc. The advantage of the Kroll process is reuse of chlorine and magnesium; however, the drawbacks of the Kroll process include: long process, low reduction efficiency, and high cost of reducing agent; therefore, the production cost of metallic titanium is very high. As titanium metal is more and more widely in a variety of industrial applications, ranging from aeronautic and astronautic applications, military applications, to civil applications, the research and development of new titanium refining techniques for reduction of production cost of titanium metal has become a hot spot in the research in titanium metallurgy industry.
Up to now, the molten salt electrolysis process for titanium production is regarded as the most promising substitute for the Kroll process. The molten salt electrolysis process usually comprises TiO₂molten salt electrolysis, TiCl₄molten salt electrolysis, and molten salt electrolysis of carbon thermally reduced product of TiO₂.
A typical TiO₂molten salt electrolysis is the FFC Cambridge process, i.e., solid TiO₂is used as the cathode, graphite is used as the anode, and CaCl₂is used as the electrolyte; when the applied external voltage is lower than the decomposition voltage of the molten salt, the oxygen on the cathode enters into the electrolyte in the form of ions, and diffuses to the anode, and bonds with carbon to generate CO₂or CO gas, which diffuses from the anode, while metallic titanium is kept at the cathode. Different to the conventional molten salt electrolysis process, the FFC process is an innovative process that separates metallic titanium and oxygen to obtain titanium, and has advantages including environmental friendliness, simple process, and continuous production, etc. However, up to now, the FFC process has been implemented successfully only in labs but has not been applied successfully in industrial production, mainly because that the FFC process has the following problems: the specific resistance of TiO₂cathode is high, and therefore it is difficult to achieve stable electrolysis; all impurities in the cathode (TiO₂) will remain in titanium, and therefore the obtained product has to be further purified; as a result, the production cost of metallic titanium is too high.
A typical TiCl₄molten salt electrolysis is the Ginatta electrolysis process, for which long-term and in-depth research has been made in USA, Japan, the former USSR, Italy, France, and China, etc., and several small plants have been constructed; however, these plants were closed subsequently because the expected technical and economic indexes were not achieved due to troubles occurred in the actual production, such as diaphragm damage and growth of dendritic crystals.

SUMMARY OF THE INVENTION

To overcome the drawbacks in the existing methods for production of metallic titanium, the present invention provides a novel method for production of metallic titanium and metallic titanium obtained with the method.
The present invention provides a method for production of metallic titanium, comprising: taking a titaniferous material as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions to obtain metallic titanium; wherein, the titaniferous material is in a porous structure, with 1 mm˜10 mm average pore diameter and 20%-60% porosity, and at least a part of the titanium element in the titaniferous material exists in the form of TiO_x, wherein, 2>x>0.
The present invention further provides another method for production of metallic titanium, comprising the following steps:

- (1) contacting a molten titanium oxide-containing raw material with a carbonaceous reducing agent such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to TiO_x, wherein, 2>x>0, to obtain molten titanium slag that contains the reduction product of said TiO_x;
- (2) cooling the molten titanium slag that contains the reduction product of said TiOx obtained in step (1) to be shaped to obtain a titaniferous material, the cooling is conducted such that the average pore diameter of the titaniferous material is 1 mm˜10 mm and the porosity is 20%˜60%;
- (3) taking the titaniferous material obtained in step (2) as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions, to obtain metallic titanium.

In addition, the present invention further provides metallic titanium obtained with the method of production described above.
The inventor of the present invention found when the average port diameter of the titaniferous material was controlled to 1 mm˜10 mm and the porosity was controlled to 20%˜60%, the titaniferous material could meet the requirements for anode, and the gases (e.g., CO, CO₂, etc.) produced in the electrolysis process could diffuse successfully, and thereby the purity and yield ratio of metallic titanium were very high. Moreover, the existing molten salt electrolysis process for the carbon thermal reduction product of titanium oxide is typically the MER process, i.e., the titanium oxide and carbonaceous reducing agent are ball-milled and mixed, pressure-molded, and sintered to form the anode; or, the titanium oxide and carbonaceous reducing agent are mixed and sintered, and then mixed with carbonaceous reducing agent and binder, pressure-molded, and sintered to form the anode. The inventor of the present invention found the process was complex, and the obtained anode might be shattered easily and could not meet the requirements for use if it was not pressed tightly enough in the anode production process; whereas, severe problems such as anodic polarization might occur in the electrolytic process if the anode was pressed too tightly. Furthermore, anode material obtained through pressure-molding and sintering process usually had small pore diameter and low porosity; as a result, it is difficult for the gases (e.g. CO) produced in the electrolytic process to diffuse, and therefore the electrolysis effect was unsatisfactory. In contrast, with the method for production of titaniferous material in a preferred embodiment of the present invention, a molten titanium oxide-containing raw material is contacted with a carbonaceous reducing agent first, such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to said TiO_x, to obtain molten titanium slag that contains the reduction product of said TiO_x; then, the titanium slag that contains the reduction product of TiO_xis cooled to be shaped; in that way, on one hand, the obtained molten reduction product can be directly cooled to be shaped to form the anode, without any additional treatment (i.e., mixing, ball-milling, and pressing the titanium oxide-containing raw material and carbonaceous reducing agent to form the anode and then sintering; or pressing the mixture of obtained solid-state reduction product and binder to form the anode and then sintering); therefore, the process is simplified; on the other hand, the reduction product obtained through contact between the titanium oxide-containing raw material and the carbonaceous reducing agent may contain one or more selected from the group consisting of TiO, Ti₂O₃, Ti₃O₅, and Ti₄O₇, the obtained reduction product is controlled to be in molten state by controlling the contact conditions, and the molten reduction product is directly cooled to be shaped; thus, the reduction product is in a homogeneous state, and thereby the obtained anode has homogeneous composition, and the electrolytic process is stable.
Other characteristics and advantages of the present invention will be further detailed in the embodiments hereunder.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereunder the embodiments of the present invention will be detailed. It should be appreciated that the embodiments described here are only provided to describe and explain the present invention, but shall not be deemed as constituting any limitation to the present invention.
The method for production of metallic titanium provided in the present invention comprises: taking a titaniferous material as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying electrolysis under electrolytic conditions to obtain metallic titanium; wherein, the titaniferous material is in a porous structure, and has average pore diameter of 1 mm˜10 mm, preferably 3 mm˜7 mm, and porosity of 20%˜60%, preferably 40%˜60%; and at least a part of the titanium element in the titaniferous material exists in the form of TiO_x, wherein, 2>x>0.
It is known to those skilled in the art: the fusion electrolysis process requires that the anode must has certain solubility in the molten salt electrolyte, but since titanium oxide has very low or even zero solubility in the molten salt electrolyte, it can't be used directly as the anode to obtain metallic titanium by electrolysis; therefore x≠2. However, the solubility of low-valence titanium oxides of TiO_x(2>x>0) in the molten salt electrolyte can meet the demand for electrolysis. Moreover, it is known from the principle of molten electrolysis: low-valence titanium oxides of TiO_x(2>x>0) can also meet other requirements of the anode for molten salt electrolysis. Therefore, the value of x is not confined specifically in the present invention, as long as it is within the range described above.
In the present invention, though the content of TiO_x(2>x>0) in the titaniferous material can be selected and changed within a wide range, preferably the content of TiO_xin the titaniferous material is determined as ≧45 wt. %, in order to improve the electrolytic efficiency.
No confinement is defined specifically for the method for production of the titaniferous material in the present invention, as long as the method can control the average pore diameter and porosity within the ranges described above; preferably, the titaniferous material is produced with a method of production that comprises the following steps:

- (1) contacting a molten titanium oxide-containing raw material with a carbonaceous reducing agent such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to said TiOx, to obtain molten titanium slag that contains the reduction product of said TiOx;
- (2) cooling the molten titanium slag that contains the reduction product of said TiOx obtained in step (1) to be shaped.

Wherein, it is noted that the cooling is natural cooling without application of any external pressure. The cooling conditions usually include pressure and cooling rate. To obtain a titaniferous material that has the above-mentioned average pore diameter and porosity, for example, the cooling is conducted in the pressure of 0.9×10⁵˜1.2×10⁵Pa (absolute pressure), the cooling rate of 100˜150° C./h.
In the present invention, as shown above, the molten titanium oxide-containing raw material is contacted with a carbonaceous reducing agent, and the contact conditions are controlled to ensure the titanic compounds in the titanium oxide-containing raw material are reduced to low-valence titanium compounds (higher than zero-valence and lower than four-valence) and the products are in molten state, so that the reduction products in different valence states can interact to achieve a homogeneous state. More importantly, after the titanium slag that contains the molten reduction product of low-valence titanium is cooled to be shaped, the obtained titaniferous material is in a porous structure, which can effectively ensure that the gases (CO, CO₂), etc.) produced in the electrolysis process diffuse successfully, and therefore the electrolysis result is very good.
In the present invention, the purpose of contact between the titanium oxide-containing raw material and the carbonaceous reducing agent is to reduce the high-valence titanium in the titanium oxide-containing raw material to low-valence titanium, which has cavities and is in a nature between conductor and semiconductor; therefore, the low-valence titanium has higher electrical conductivity and can be dissolved in the molten salt electrolyte. The contact conditions include contact temperature, contact pressure, and contact duration, wherein, the contact conditions can be determined as appropriate, as long as they ensure that the titanium oxide in the titanium oxide-containing raw material can be reduced to low-valence titanium and molten titanium slag that contains the reduction product of low-valence titanium can be obtained. Preferably, the contacting is conducted in the temperature of 1,650˜2,000° C., the pressure of −100 Pa˜100 Pa (absolute pressure), and the time of 2˜10 h; more preferably, contacting is conducted in the temperature of 1,650˜1,750° C., the pressure of −50 Pa˜50 Pa (absolute pressure), and the time of 3˜5 h. Under those conditions, the titanium oxide in the titanium oxide-containing raw material will be reduced fully or almost fully to low-valence titanium.
Owing to the reducibility of the carbonaceous reducing agent, titanium oxide can be reduced to the product with valence lower than tetravalence instead of simple substance, such as one or more selected from the group consisting of TiO, Ti₂O₃, Ti₃O₅, and Ti₄O₇, when the oxidation-reduction reaction between the carbonaceous reducing agent and the titanium oxide-containing raw material happens. It is known to those skilled in the art: the fusion electrolysis process requires that the anode must has certain solubility in the molten salt electrolyte, but since titanium oxide has very low or even zero solubility in the molten salt electrolyte, it can't be used directly as the anode to obtain metallic titanium by electrolysis; therefore x≠2. However, the solubility of low-valence titanium oxides of TiO_x(2>x>0) in the molten salt electrolyte can meet the demand for electrolysis. Moreover, it is known from the principle of molten electrolysis: low-valence titanium oxides of TiO_x(2>x>0) can also meet other requirements of the anode for molten salt electrolysis. Therefore, the composition of the reduction product is not confined specifically in the method provided in the present invention, as long as titanium oxide is reduced to low-valence titanium compounds, such as one or more selected from the group consisting of TiO, Ti₂O₃, Ti₃O₅, and Ti₄O₇.
In the present invention, the quantity ratio of titanic compounds in the titanium oxide-containing raw material to carbon in the carbonaceous reducing agent can vary within a wide range, for example, calculated in titanium oxide, the mol ratio of titanic compounds in the titanium oxide-containing raw material to carbon in the carbonaceous reducing agent can be 1:1˜3. Furthermore, owing to the fact that the titanium oxide-containing raw material usually contains other reducing substances, such as iron ions, etc., the actual quantity of the carbonaceous reducing agent is often slightly more than the demanded quantity in order to further improve the reduction result, preferably, calculated in titanium oxide, the mol ratio of titanic compounds in the titanium oxide-containing raw material to carbon in the carbonaceous reducing agent is 1:1.5˜3, more preferably 1:1.5˜2.5.
In the present invention, the titanium oxide-containing raw material can be any existing titanium oxide-containing material, for example, the titanium oxide-containing material can be titanium concentrates and/or titaniferous slag. The titanium concentrates are refined from ilmenite or titaniferous magnetite, mainly containing titanium oxide (42˜65 wt. %), iron sesquioxide (5˜40 wt. %), iron oxide (5˜40 wt. %), and some chemical compounds of phosphorus, sulfur, magnesium, and calcium elements (2˜10 wt. %). The titaniferous slag refers to the slag produced when other valuable metals are extracted from titaniferous minerals, mainly containing titanium oxide (15˜30 wt. %), calcium oxide (10˜25 wt. %), aluminum oxide (10˜20 wt. %), and silicon dioxide (10˜28 wt. %).
In the present invention, the carbonaceous reducing agent can be any existing carbonaceous reducing agent, as long as it can reduce the titanium oxide in the titanium oxide-containing raw material to low-valence titanium compounds (e.g., trivalent and bivalent titanium compounds); for example, the carbonaceous reducing agent can be one or more selected from the group consisting of blind coal, soft coal, wood charcoal, coke, and refinery coke. The blind coal is the coal that has the highest degree of coalification, and high content of carbon (80 wt. % or more) and low content of volatiles (lower than 10 wt. %). The soft coal has 75˜90 wt. % carbon content. The wood charcoal has 65˜95 wt. % carbon content. The coke is produced from soft coal by heating to 950˜1050° C., drying, thermal decomposition, melting, agglomeration, solidification, and contraction, etc., and has 75˜85 wt. % carbon content. The refinery coke is a product produced from crude oil by distilling crude oil to separate light oil from heavy oil, and then treating the heavy oil by pyrolysis. Viewed from the appearance, the coke is in the form of black blocks (or granules) in irregular shapes and different sizes, and has metallic luster; the coke granules have a porous structure, and have 90 wt. % or higher carbon content; the rest components are hydrogen, oxygen, nitrogen, sulfur and metal elements.
The species of the metal for cathode is not confined specifically in the present invention, as long as the metal material can work with the anode in the present invention to accomplish electrolysis, so as to obtain metallic titanium. However, to improve the service life of anode and the purity of the obtained metallic titanium, preferably the metal material for cathode can be one or more selected from the group consisting of carbon steel, molybdenum, copper, and nickel.
Usually, electrolyte refers to a chemical compound that can conduct electricity after it is dissolved in water or when it is in molten state. In the present invention, in order to improve the purity of the obtained metallic titanium and reduce the introduction of foreign substances, preferably a molten salt material is used as the electrolyte, for example, the molten salt material can be molten salt formed from alkali chloride and/or alkaline earth metal chloride. For example, the alkali chloride can be sodium chloride and/or potassium chloride; the alkaline earth metal chloride can be magnesium chloride and/or calcium chloride.
In the present invention, though the conditions of electrolysis don't have significant influence on the purity of the obtained metallic titanium, to make a tradeoff between efficiency and yield, preferably the electrolysis conditions include anode current density of 0.05˜2 A/cm², and cathode current density of 0.05˜2 A/cm²; more preferably, the electrolysis conditions include anode current density of 0.1˜1 A/cm², and cathode current density of 0.1˜1 A/cm².
In the present invention, the temperature of the molten salt (i.e., the temperature of electrolysis) can vary in a wide range, as long as the temperature is higher than the melting temperature of the salt that forms the molten salt and lower than the vaporization temperature and decomposition temperature of the salt that forms the molten salt; for example, the temperature of electrolysis can be 600˜900° C., preferably 600˜800° C. The time of electrolysis can be chosen reasonably according to the quantity of the low-valence titanium to be electrolyzed and the conditions of electrolysis, so that at least 90% low-valence titanium is converted to metallic titanium.
In the present invention, the metallic titanium produced by electrolysis tends to react with the oxygen in the air at the temperature of electrolysis; therefore, to improve the purity of the obtained metallic titanium, preferably the electrolysis is conducted in inert atmosphere. The inert atmosphere can be selected from nitrogen and one or more of zero-group gases in the periodic table of elements, and is preferably argon gas.
Another method for production of metallic titanium provided in the present invention comprises the following steps:

- (1) contacting a molten titanium oxide-containing raw material with a carbonaceous reducing agent such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to TiO_x, wherein, 2>x>0, to obtain molten titanium slag that contains the reduction product of said TiO_x;
- (2) cooling the molten titanium slag that contains the reduction product of said TiO_xobtained in step (1) to be shaped to obtain a titaniferous material, the cooling is conducted such that the average pore diameter of the titaniferous material is 1 mm˜10 mm and the porosity is 20%˜60%;
- (3) taking the titaniferous material obtained in step (2) as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions, to obtain metallic titanium.

Wherein, the species and quantities of the substances in above steps, the contact conditions for contact between the titanium oxide-containing raw material and the carbonaceous reducing agent, cooling conditions, and electrolysis conditions have been described above, and will not be further detailed hereunder.
In addition, the present invention further provides metallic titanium obtained with the method described above.
Hereunder the present invention will be further detailed in the embodiments.
In the following examples and comparative examples, the yield ratio of metallic titanium is equal to the actual yield of metallic titanium/theoretical yield of metallic titanium×100%, the average pore diameter of the titaniferous material is measured with a Scanning Electron Microscope (SEM) (from Hitachi, model S-4700), and the porosity is measured with a nitrogen adsorption method.

EXAMPLE 1

Feed 100 g molten titanium concentrates produced from Panzhihua (wherein, TiO₂: 47.5 wt. %, Fe₂O₃: 5.74 wt. %, FeO: 34.48 wt. %, CaO: 1.42 wt. %, MgO: 6.22 wt. %) and 14 g blind coal (wherein, carbon content: 78.5 wt. %) into an electric furnace, and smelt for 5 h at 1750° C. temperature and −50 Pa pressure (absolute pressure), to obtain molten titanium slag. Pour the molten titanium slag into a Φ400×600 cast steel mold, and cool down the molten titanium slag without application of external pressure (pressure: 0.9×10⁵Pa, cooling rate: 150° C./h), to obtain a titaniferous material in porous structure, wherein, the average pore diameter of the titaniferous material is 5.75 mm, and the porosity is 45%. Take the titaniferous material as the anode, a Φ80×600 carbon steel rod as the cathode, and NaCl—KCl (weight ratio: 1:1) as the molten salt electrolyte, and electrolyze for 300 min at 820° C. under argon shielding, wherein, the anodic current density is 0.2 A/cm², and the cathode current density is 0.2 A/cm². After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 22.5 g metallic titanium-containing product; the yield ratio of metallic titanium is 46.66%. In the process of electrolysis, the current fluctuation is very low, indicating the process of electrolysis is stable. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 98.5 wt. %, Fe: 0.95 wt. %, O: 0.37 wt. %, and H: 0.18 wt. %.

EXAMPLE 2

Feed 60 g molten titanium concentrates produced from Panzhihua (wherein, TiO₂: 47.5 wt. %, Fe₂O₃: 5.74 wt. %, FeO: 34.48 wt. %, CaO: 1.42 wt. %, MgO: 6.22 wt. %), 40 g titanium concentrates produced from Yunan (wherein, TiO₂: 49.85 wt. %, Fe2O₃: 9.68 wt. %, FeO: 36.50 wt. %, CaO: 0.24 wt. %, MgO: 1.99 wt. %), and 20 g blind coal (wherein, carbon content: 78.5 wt. %) into an electric furnace, and smelt for 3 h at 1650° C. temperature and 50 Pa pressure (absolute pressure), to obtain molten titanium slag. Pour the molten titanium slag into a Φ300×600 cast steel mold, and cool down the molten titanium slag without application of external pressure (pressure: 1.0×10⁵Pa, cooling rate: 100° C./h), to obtain a titaniferous material in porous structure, wherein, the average pore diameter of the titaniferous material is 6.5 mm, and the porosity is 55.3%. Take the titaniferous material as the anode, a Φ60×600 carbon steel rod as the cathode, and NaCl—KCl (weight ratio: 1:1) as the molten salt electrolyte, and electrolyze for 300 min at 900° C. in inert atmosphere, wherein, the anodic current density is 2 A/cm², and the cathode current density is 1 A/cm². In the process of electrolysis, the current fluctuation is very low, indicating the process of electrolysis is stable. After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 14 g metallic titanium-containing product; the yield ratio of metallic titanium is 48.03%. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 97.78 wt. %, Fe: 0.85 wt. %, O: 1.25 wt. %, and H: 0.12 wt. %.

EXAMPLE 3

Feed 100 g molten titanium concentrates produced from Yunan (wherein, TiO₂: 49.85 wt. %, Fe₂O₃: 9.68 wt. %, FeO: 36.50 wt. %, CaO: 0.24 wt. %, MgO: 1.99 wt. %) and 22 g coke (wherein, carbon content: 85.5 wt. %) into an electric furnace, and smelt for 4 h at 1700° C. temperature and 5 Pa pressure (absolute pressure), to obtain molten titanium slag. Pour the molten titanium slag into a Φ200×400 cast steel mold, and cool down the molten titanium slag without application of external pressure (pressure: 1.2×10⁵Pa, cooling rate: 120° C./h), to obtain a titaniferous material in porous structure, wherein, the average pore diameter of the titaniferous material is 3.5 mm, and the porosity is 60%. Take the titaniferous material as the anode, a Φ50×400 carbon steel rod as the cathode, and NaCl—KCl (weight ratio: 1:1) as the molten salt electrolyte, and electrolyze for 210 min at 850° C. in inert atmosphere, wherein, the anodic current density is 1 A/cm², and the cathode current density is 1.5 A/cm². In the process of electrolysis, the current fluctuation is very low, indicating the process of electrolysis is stable. After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 23.5 g metallic titanium-containing product; the yield ratio of metallic titanium is 46.33%. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 98.28 wt. %, Fe: 0.55 wt. %, O: 1.05 wt. %, and H: 0.12 wt. %.

EXAMPLE 4

Product metallic titanium with the method described in embodiment 2, with the following difference: the temperature of contact between the molten titanium concentrates produced from Panzhihua and the blind coal is 1600° C. After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 12 g metallic titanium-containing product; the yield ratio of metallic titanium is 41.05%. In the process of electrolysis, the current fluctuation is very low, indicating the process of electrolysis is stable. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 97.5 wt. %, Fe: 1.55 wt. %, O: 1.25 wt. %, and H: 0.12 wt. %.

Comparative Example 1

Produce metallic titanium with the method described in embodiment 1, with the following difference: the anode for production of metallic titanium is obtained with the following method:
Feed 100 g titanium concentrates produced from Panzhihua (wherein, TiO₂: 47.5 wt. %, Fe₂O₃: 5.74 wt. %, FeO: 34.48 wt. %, CaO: 1.42 wt. %, MgO: 6.22 wt. %) and 14 g blind coal (wherein, carbon content: 78.5 wt. %) into an electric furnace, and smelt for 5 h at 1750° C. temperature and −50 Pa pressure (absolute pressure), to obtain molten titanium slag. Cool down the obtained molten titanium slag and then load it into a Φ400×600 cast steel mold, and press to the expected shape at 50,000 psi pressure, to obtain a shaped titaniferous material. Wherein, the average pore diameter of the titaniferous material is 200 nm, and the porosity is 10%. In the process of electrolysis, the current fluctuation is high, indicating the process of electrolysis is unstable. After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 11.9 g metallic titanium-containing product; the yield ratio of metallic titanium is 24.30%. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 97 wt. %, Fe: 1.95 wt. %, O: 0.57 wt. %, and H: 0.48 wt. %.

Comparative Example 2

Produce metallic titanium with the method described in embodiment 1, with the following difference: the anode for production of metallic titanium is obtained with the following method:
Feed 100 g titanium concentrates produced from Panzhihua (wherein, TiO₂: 47.5 wt. %, Fe₂O₃: 5.74 wt. %, FeO: 34.48 wt. %, CaO: 1.42 wt. %, MgO: 6.22 wt. %) and 14 g blind coal (wherein, carbon content: 78.5 wt. %) into a ball-mill jar and mill for 60 min., and then feed the mixture into a Φ200×400 cast steel mold and press to expected shape at 50,000 psi pressure, and then sinter for 5 h at 1750° C. temperature and −50 Pa pressure (absolute pressure), to obtain a titaniferous material. Wherein, the average pore diameter of the titaniferous material is 300 nm, and the porosity is 15%. In the process of electrolysis, the current fluctuation is high, indicating the process of electrolysis is unstable. After the electrolysis is completed, take out the cathode, cool down it naturally, wash with 0.5 wt. % dilute hydrochloric acid and deionized water in sequence, and then dry the product, to obtain 12.1 g metallic titanium-containing product; the yield ratio of metallic titanium is 24.73%. Measured with X fluorescent analysis method, the constituting elements of the metallic titanium-containing product are as follows: Ti: 97.08 wt. %, Fe: 1.45 wt. %, O: 0.57 wt. %, and H: 0.48 wt. %.
It is seen from the comparison between the example 1 and the comparative examples 1˜2: both the yield ratio and the purity of the product are higher, when the method provided in the present invention is used to produce metallic titanium. Moreover, the reduction product obtained in the present invention is in molten state, and therefore the reduction products in different valence states can interact with each other to achieve a satisfactory result; in addition, after cooling to be shaped, the obtained titaniferous material is in a porous structure, which can effectively ensure that the gases (CO, CO₂), etc.) produced in the electrolysis process diffuse successfully, and therefore the electrolysis process is more stable.
While some preferred embodiments of the present invention are described above, the present invention is not limited to the details in those embodiments. Those skilled in the art can make modifications and variations to the technical scheme of the present invention, without departing from the spirit of the present invention. However, all these modifications and variations shall be deemed as falling into the protected domain of the present invention.
In addition, it should be noted: the specific technical features described in above embodiments can be combined in any appropriate form, provided that there is no conflict. To avoid unnecessary repetition, the possible combinations are not described specifically in the present invention.
Moreover, the different embodiments of the present invention can be combined freely as required, as long as the combinations don't deviate from the ideal and spirit of the present invention. However, such combinations shall also be deemed as falling into the scope disclosed in the present invention.

Claims

1. A method for production of metallic titanium, comprising: taking a titaniferous material as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions to obtain metallic titanium; wherein, the titaniferous material is in a porous structure, with 1 mm˜10 mm average pore diameter and 20%˜60% porosity, and at least a part of the titanium element in the titaniferous material exists in the form of TiO_x, wherein, 2>x>0.

2. The method according to claim 1, wherein, the average pore diameter of the titaniferous material is 3mm˜7mm, and the porosity is 40%˜60%.

3. The method according to claim 1, wherein, the content of said TiOx in the titaniferous material is not lower than 45 wt. %.

4. The method according to claim 1, wherein, the titaniferous material is obtained with a method that comprises the following steps:

(1) contacting a molten titanium oxide-containing raw material with a carbonaceous reducing agent such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to said TiO_x, to obtain molten titanium slag that contains the reduction product of said TiO_x;

(2) cooling the molten titanium slag that contains the reduction product of said TiOx obtained in step (1) to be shaped.

5. The method according to claim 4, wherein, the cooling is conducted in the pressure of 0.9×10⁵˜1.2×10⁵Pa.

6. The method according to claim 4, wherein, the cooling is conducted in the cooling rate of 100˜150° C./h.

7. The method according to claim 4, wherein, in step (1), the contacting is conducted in the temperature of 1,650˜2,000° C., the pressure of −100 Pa˜100 Pa, and the time of 2˜10 h; calculated in titanium oxide, the mol ratio of titanic compounds in the titanium oxide-containing raw material to carbon in the carbonaceous reducing agent is 1:1˜3.

8. The method according to claim 4, wherein, in step (1), the titanium oxide-containing raw material is composed of titanium concentrates and/or titaniferous slag; the carbonaceous reducing agent is one or more selected from the group consisting of blind coal, soft coal, wood charcoal, coke, and refinery coke.

9. The method according to claim 1, wherein, the metal material for cathode is one or more selected from the group consisting of carbon steel, molybdenum, copper, and nickel; the molten salt is molten alkali chloride and/or alkaline earth metal chloride.

10. The method according to claim 1, wherein, the electrolysis conditions include anode current density of 0.05˜2 A/cm², and cathode current density of 0.05˜2 A/cm², and temperature of electrolysis of 600˜900° C.

11. Metallic titanium obtained with the method according to claim 1.

12. A method for production of metallic titanium, comprising the following steps:

(1) contacting a molten titanium oxide-containing raw material with a carbonaceous reducing agent such that the titanium oxide in the titanium oxide-containing raw material is fully or partially reduced to TiOx, wherein, 2>x>0, to obtain molten titanium slag that contains the reduction product of said TiOx;

(2) cooling the molten titanium slag that contains the reduction product of said TiOx obtained in step (1) to be shaped to obtain a titaniferous material, the cooling is conducted such that the average pore diameter of the titaniferous material is 1 mm˜10 mm and the porosity is 20%˜60%;

(3) taking the titaniferous material obtained in step (2) as the anode, a metal material as the cathode, and a molten salt material as the electrolyte, and carrying out electrolysis under electrolytic conditions, to obtain metallic titanium.

13. The method according to claim 12, wherein, the cooling is conducted in the pressure of 0.9×10⁵˜1.2×10⁵Pa.

14. The method according to claim 12, wherein, the cooling is conducted in the cooling rate of 100˜150° C./h.

15. The method according to claim 12, wherein, in step (1), the contacting is conducted in the temperature of 1,650˜2,000° C., the pressure of −100 Pa˜100 Pa, and the time of 2˜10 h.

16. The method according to claim 12, wherein, in step (1), calculated in titanium oxide, the mol ratio of titanic compounds in the titanium oxide-containing raw material to carbon in the carbonaceous reducing agent is 1:1˜3.

17. The method according to claim 12, wherein, in step (1), the titanium oxide-containing raw material is composed of titanium concentrates and/or titaniferous slag; the carbonaceous reducing agent is one or more selected from the group consisting of blind coal, soft coal, wood charcoal, coke, and refinery coke.

18. The method according to claim 12, wherein, the metal material for cathode is one or more selected from the group consisting of carbon steel, molybdenum, copper, and nickel; the molten salt is molten alkali chloride and/or alkaline earth metal chloride.

19. The method according to claim 12, wherein, the electrolysis conditions include anode current density of 0.05˜2 A/cm², and cathode current density of 0.05˜2 A/cm², and temperature of electrolysis of 600×900° C.

20. Metallic titanium obtained with the method according to claim 12.