CN115921884A - Method for preparing metallic titanium powder by metallothermic reduction of titanium dioxide - Google Patents

Abstract

The invention relates to a method for preparing metallic titanium powder by metallothermic reduction of titanium dioxide, which is respectively carried out in a low-temperature section and a high-temperature section step by step: firstly, in a low-temperature section, under the conditions that the pressure is less than 30Pa and the temperature is 800-1000 ℃, the bottom of a graphite crucible mainly contains calcium carbide and magnesium oxide which react to generate magnesium vapor, and the magnesium vapor rises to reduce the titanium dioxide on the upper layer; after magnesium oxide is consumed, the temperature of the atmosphere furnace is increased to 1100-1300 ℃ in the reduction process of the high-temperature section, calcium vapor is generated mainly by the reaction of excessive calcium carbide and calcium oxide in the stage, the calcium vapor rises to further reduce the product obtained in the low-temperature section, and finally metal titanium is prepared. The method takes titanium dioxide as a raw material, prepares the metal titanium by a direct thermal reduction method, shortens the reaction flow and simplifies the reaction steps compared with the Kroll method used in the industry at present, and the reduction process is easy to control and simple to operate. Meanwhile, a temperature-divided reduction method is adopted, so that the preparation cost is reduced, and the energy is saved.

Description

A kind of method that metallothermic reduction titanium dioxide prepares metal titanium powder

technical field

The invention belongs to the technical field of metallurgy and metal material preparation, and in particular relates to a method for preparing metal titanium powder by metallothermic reduction of titanium dioxide.

Background technique

As an important strategic metal resource, titanium is widely used in high-tech fields such as semiconductor integrated circuits, military industry, aerospace, and 3D printing. With the continuous merger, reorganization and expansion of large domestic sponge titanium production enterprises, my country's sponge titanium production capacity has increased year by year. In 2020, my country's titanium sponge production capacity will reach 177,000 tons, an increase of 12% over the previous year. The Kroll method is currently the main process for the industrial production of titanium metal, but this process is a semi-continuous process, which has problems such as long production process, high cost, and low product purity, which restricts the large-scale development of the titanium smelting industry. Therefore, the development of short-process, low-cost new titanium metallurgy technology is of great significance to the green and sustainable development of my country's titanium industry.

The Kroll method is a typical representative of the metal thermal reduction method, and it is also the main method for the industrial production of titanium metal. This process first converts titanium-rich material into titanium tetrachloride, and then produces sponge titanium through metal magnesium reduction. The product contains high impurities, such as 0.3% to 0.9% of oxygen, carbon and hydrogen, which affects the strength of the product. , ductility and impact toughness limit the application of sponge titanium in high-end titanium alloys. Compared with the complex process of the Kroll method, the direct reduction of titanium dioxide as raw material to prepare titanium metal has become one of the important directions for the research and development of short-process and low-cost titanium smelting technology. CN102921953A discloses a method for preparing metal titanium powder by using aluminum powder, calcium oxide and titanium dioxide as raw materials. The method utilizes the calcium vapor generated by the reaction of the aluminum powder and the calcium oxide to directly reduce the titanium dioxide, thereby eliminating the calcium condensation and remelting gasification process, shortening the reaction process and saving energy. CN101628337A discloses a method for producing metallic titanium powder by reducing titanium dioxide with magnesium vapor. In the above technology, the use of calcium vapor to reduce titanium dioxide requires a higher temperature, but the reduction ability of magnesium vapor is lower than that of calcium vapor, so the oxygen content in the metal calcium product obtained by reduction is relatively high. Research on more energy-saving and efficient titanium metal preparation methods is of great significance to the short-process, low-cost smelting of titanium and the high-value utilization of titanium materials.

Contents of the invention

The invention provides a method for preparing metal titanium powder by metallothermic reduction of titanium dioxide, the purpose of which is to realize direct reduction of titanium dioxide to prepare metal titanium powder with low impurity content.

The present invention is realized through the following technical solutions:

A method for preparing metallic titanium powder by metallothermic reduction of titanium dioxide. The method uses titanium dioxide as a raw material. The reduction steps successively include vacuum thermal reduction of magnesium vapor and vacuum thermal reduction of calcium vapor, specifically comprising the following steps:

(1) Mix titanium dioxide and anhydrous calcium chloride with a particle size ranging from 100 to 1000 mesh evenly at a mass ratio of 1:1 to 3:1, and press it into block I under a pressure of 10 MPa;

(2) Mix magnesium oxide, calcium oxide, and calcium carbide with a particle size ranging from 100 to 1000 mesh evenly at a mass ratio of 1:1:1 to 1:1:2, and press them into block II under a pressure of 5-10 MPa;

(3) Place the block II prepared in step (2) in a molybdenum boat, and place it on the lower layer of the graphite crucible, and place the block I prepared in the step (1) on the upper layer of the graphite crucible, and separate it with a porous molybdenum plate. Open block I and block II, and put a graphite cover on top of the graphite crucible;

(4) Heat up the graphite crucible obtained in step (3) to 800-1000° C. under a pressure of less than 30 Pa, and keep it warm for 180-360 minutes. At this time, the bottom of the graphite crucible is mainly composed of calcium carbide and magnesium oxide that react to generate magnesium vapor, magnesium vapor Rise to reduce the titanium dioxide on the upper layer; then raise the temperature to 1100-1300°C and keep it warm for 180-360 minutes. At this stage, the remaining calcium carbide and calcium oxide react to generate calcium vapor, and the calcium vapor rises to further reduce the product of the previous stage, and obtain The bulk material; after the first reduction process of this step, titanium mainly exists in the form of low-valent titanium oxide and a small amount of metal titanium; after the second reduction process, titanium mainly exists in the form of metal titanium;

(5) The bulk material obtained in step (4) is stirred and leached in a hydrochloric acid solution with a pH of 0.5 to 1 for 4-8 hours, wherein, during the stirring process, the pH of the solution is adjusted by dropping a 1mol/L hydrochloric acid solution to always be in the above range Inside, and control the stirring speed to 100~300r/min;

(6) Filter and separate the material obtained in step (5) to obtain leachate and solid, and repeatedly wash the solid with deionized water and absolute ethanol until the filtrate is neutral, and dry the filter cake at 40-80°C for 8-16 hours, That is, titanium metal powder is obtained.

The block I in the step (1) has a size of Φ15×20˜Φ20×20mm.

The size of the block II in the step (2) is Φ15×10˜Φ20×10 mm.

The heating rate in the step (4) is 10° C./min.

The liquid-solid ratio during stirring and leaching in the step (5) is greater than 15:1.

Compared with the prior art, the present invention has the following advantages:

(1) The process is short. The present invention uses titanium dioxide as a raw material to prepare titanium sponge through direct thermal reduction of titanium dioxide; while the Kroll method currently used in industry uses titanium dioxide as a raw material, prepares titanium tetrachloride through chlorination, and then reduces titanium tetrachloride through metal heat Get titanium sponge. Therefore, compared with the Kroll method, the method simplifies the reaction steps, shortens the reaction process, and the reduction process is easy to control and simple to operate.

(2) The product quality is high. The present invention proposes a step-by-step reduction of titanium dioxide by magnesium and calcium to prepare metal titanium in a vacuum atmosphere. The reduction process is easy to control, and the content of impurities such as oxygen and nitrogen in the metal titanium powder obtained by the two-step reduction method is relatively low. The high-value utilization of titanium is of great significance.

(3) Low cost. In the present invention, the reductant metal magnesium and metal calcium are synchronously generated by the reaction of calcium carbide, magnesium oxide and calcium oxide respectively. At the same time, the vacuum reduction process is carried out step by step in the low-temperature section and the high-temperature section respectively. While realizing product quality, it also reduces The preparation cost of titanium metal, as well as saving energy.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

Example 1

(1) Mix titanium dioxide with a particle size range of 100-200 mesh and anhydrous calcium chloride at a mass ratio of 2:1, and press it into a block I with a size of Φ15×20mm under a pressure of 10MPa;

(2) Mix magnesium oxide, calcium oxide, and calcium carbide with a particle size ranging from 100 to 200 mesh evenly at a mass ratio of 1:1:1, and press it into block II with a size of Φ15×10mm under a pressure of 5 MPa;

(3) Place the block II prepared in step (2) in a molybdenum boat, and place it on the lower layer of the graphite crucible, and place the block I prepared in the step (1) on the upper layer of the graphite crucible, and separate it with a porous molybdenum plate. Open block I and block II, and put a graphite cover on top of the graphite crucible;

(4) Place the graphite crucible obtained in step (3) in a vacuum atmosphere furnace, and the vacuum thermal reduction process is carried out step by step in the low temperature section and the high temperature section: first, under the pressure less than 30Pa, the atmosphere furnace is heated at a rate of 10°C Heating up to 800°C/min, and keeping warm at this reaction temperature for 360min, at this time, the bottom of the graphite crucible is mainly composed of calcium carbide and magnesium oxide reacting to generate magnesium vapor, and the magnesium vapor rises to reduce the titanium dioxide on the upper layer; then the atmosphere furnace is heated at a rate of 10 ℃/min to raise the temperature to 1100℃, and then keep it at this temperature for 360min. In this stage, the remaining calcium carbide and calcium oxide react to generate calcium vapor, and the calcium vapor rises to further reduce the product of the previous stage, and obtain the reduced lump Material; Titanium mainly exists in the form of low-valent titanium oxide and a small amount of metal titanium after the first stage reduction process of this step; titanium mainly exists in the form of metal titanium after the second stage reduction process;

(5) The bulk material obtained in step (4) is stirred and leached for 6 hours in a hydrochloric acid solution with a pH of 0.5. Within the above range, and control the stirring speed to 200r/min;

(6) Filter and separate the material obtained in step (5) to obtain leachate and solids, and repeatedly wash the solids with deionized water and absolute ethanol until the filtrate is neutral, and place the filter cake in a vacuum drying oven at 60°C After drying for 12 hours, titanium metal powder is obtained.

Example 2

(1) Mix titanium dioxide with a particle size range of 300-500 mesh and anhydrous calcium chloride at a mass ratio of 1:1, and press it into a block I with a size of Φ20×20mm under a pressure of 10MPa;

(2) Mix magnesium oxide, calcium oxide, and calcium carbide with a particle size ranging from 300 to 500 mesh evenly at a mass ratio of 1:1:1, and press it into block II with a size of Φ20×10mm under a pressure of 6 MPa;

(3) Place the block II prepared in step (2) in a molybdenum boat, and place it on the lower layer of the graphite crucible, and place the block I prepared in the step (1) on the upper layer of the graphite crucible, and separate it with a porous molybdenum plate. Open block I and block II, and put a graphite cover on top of the graphite crucible;

(4) Place the graphite crucible obtained in step (3) in a vacuum atmosphere furnace, and the vacuum thermal reduction process is carried out step by step in the low temperature section and the high temperature section: first, under the pressure less than 30Pa, the atmosphere furnace is heated at a rate of 10°C /min to 900°C, and keep warm at this reaction temperature for 240min. At this time, the bottom of the graphite crucible is mainly composed of calcium carbide and magnesium oxide that react to generate magnesium vapor, and the magnesium vapor rises to reduce the titanium dioxide on the upper layer; then the atmosphere furnace is heated at a rate of 10 ℃/min to raise the temperature to 1200℃, and then keep it at this temperature for 240min. In this stage, the remaining calcium carbide and calcium oxide react to generate calcium vapor, and the calcium vapor rises to further reduce the product of the previous stage, and obtain the reduced lump Material; Titanium mainly exists in the form of low-valent titanium oxide and a small amount of metal titanium after the first stage reduction process of this step; titanium mainly exists in the form of metal titanium after the second stage reduction process;

(5) The bulk material obtained in step (4) is stirred and leached in a hydrochloric acid solution with a pH of 1 for 8 hours, and the liquid-solid ratio is 18:1, wherein, during the stirring process, the pH of the solution is adjusted by dripping a 1mol/L hydrochloric acid solution. Within the above range, and control the stirring speed to 300r/min;

(6) Filter and separate the material obtained in step (5) to obtain leachate and solids, and repeatedly wash the solids with deionized water and absolute ethanol until the filtrate is neutral. After drying for 8 hours, metal titanium powder is obtained.

Example 3

(1) Mix titanium dioxide with a particle size range of 800-1000 mesh and anhydrous calcium chloride at a mass ratio of 3:1, and press it into a block I with a size of Φ18×18mm under a pressure of 10MPa;

(2) Mix magnesium oxide, calcium oxide, and calcium carbide with a particle size ranging from 800 to 1,000 mesh evenly at a mass ratio of 1:1:2, and press it into block II with a size of Φ18×18mm under a pressure of 5 MPa;

(3) Place the block II prepared in step (2) in a molybdenum boat, and place it on the lower layer of the graphite crucible, and place the block I prepared in the step (1) on the upper layer of the graphite crucible, and separate it with a porous molybdenum plate. Open block I and block II, and put a graphite cover on top of the graphite crucible;

(4) Place the graphite crucible obtained in step (3) in a vacuum atmosphere furnace, and the vacuum thermal reduction process is carried out step by step in the low temperature section and the high temperature section: first, under the pressure less than 30Pa, the atmosphere furnace is heated at a rate of 10°C /min to 1000°C, and keep warm at this reaction temperature for 180min. At this time, the bottom of the graphite crucible is mainly composed of calcium carbide and magnesium oxide that react to generate magnesium vapor, and the magnesium vapor rises to reduce the titanium dioxide on the upper layer; then the atmosphere furnace is heated at a rate of 10 ℃/min to 1300 ℃, and then keep it at this temperature for 180min. This stage is mainly for the remaining calcium carbide to react with calcium oxide to generate calcium vapor. The calcium vapor rises to further reduce the product of the previous stage, and obtain the reduced lump Material; Titanium mainly exists in the form of low-valent titanium oxide and a small amount of metal titanium after the first stage reduction process of this step; titanium mainly exists in the form of metal titanium after the second stage reduction process;

(5) The bulk material obtained in step (4) is stirred and leached for 4 hours in a hydrochloric acid solution with a pH of 1, and the liquid-solid ratio is 20:1, wherein, during the stirring process, the pH of the solution is adjusted by dripping a 1mol/L hydrochloric acid solution. Within the above range, and control the stirring speed to 100r/min;

(6) Filter and separate the material obtained in step (5) to obtain leachate and solids, and repeatedly wash the solids with deionized water and absolute ethanol until the filtrate is neutral. After drying for 16 hours, titanium metal powder is obtained.

Example 4

(1) Mix titanium dioxide with a particle size range of 500-1000 mesh and anhydrous calcium chloride at a mass ratio of 2:1, and press it into a block I with a size of Φ20×20mm under a pressure of 10MPa;

(2) Mix magnesium oxide, calcium oxide, and calcium carbide with a particle size ranging from 500 to 1,000 mesh at a mass ratio of 1:1:1, and press it into block II with a size of Φ20×10mm under a pressure of 10MPa;

(3) Place the block II prepared in step (2) in a molybdenum boat, and place it on the lower layer of the graphite crucible, and place the block I prepared in the step (1) on the upper layer of the graphite crucible, and separate it with a porous molybdenum plate. Open block I and block II, and put a graphite cover on top of the graphite crucible;

(4) Place the graphite crucible obtained in step (3) in a vacuum atmosphere furnace, and the vacuum thermal reduction process is carried out step by step in the low temperature section and the high temperature section: first, under the pressure less than 30Pa, the atmosphere furnace is heated at a rate of 10°C /min to 1000°C, and keep warm at this reaction temperature for 180min. At this time, the bottom of the graphite crucible is mainly composed of calcium carbide and magnesium oxide that react to generate magnesium vapor, and the magnesium vapor rises to reduce the titanium dioxide on the upper layer; then the atmosphere furnace is heated at a rate of 10 ℃/min to 1300 ℃, and then keep it at this temperature for 240min. This stage is mainly for the remaining calcium carbide and calcium oxide to react to generate calcium vapor. The calcium vapor rises to further reduce the product of the previous stage, and obtain the reduced lump Material; Titanium mainly exists in the form of low-valent titanium oxide and a small amount of metal titanium after the first stage reduction process of this step; titanium mainly exists in the form of metal titanium after the second stage reduction process;

(5) The bulk material obtained in step (4) is stirred and leached in a hydrochloric acid solution with a pH of 1 for 5 hours, and the liquid-solid ratio is 16:1, wherein, during the stirring process, the pH of the solution is adjusted by dripping a 1mol/L hydrochloric acid solution. Within the above range, and control the stirring speed to 300r/min;

(6) Filter and separate the material obtained in step (5) to obtain leachate and solids, and repeatedly wash the solids with deionized water and absolute ethanol until the filtrate is neutral. After drying for 10 hours, titanium metal powder is obtained.

Comparative example 1: the Kroll method of the prior art.

Comparative example 2: the Hunter method of the prior art.

Comparative example 3: using the method in the patent application CN102921953A.

Comparative example 4: using the method in the patent application CN101628337A.

Comparative example 5: Same as Example 2, only the low-temperature section reduction of step (4) is replaced by 8h, and the high-temperature section reduction is deleted, that is: the graphite crucible obtained in step (3) is placed in a vacuum atmosphere furnace, and the vacuum thermal reduction process Carried out in the low temperature section: under the pressure of less than 30Pa, the atmosphere furnace is heated up to 900°C at a heating rate of 10°C/min, and kept at the reaction temperature for 480min to obtain the reduced block material.

The comparison of the preparation method of the sponge titanium material disclosed by the embodiment of Table 1 and some patents

As can be seen from the above table, compared with the Kroll method and the Hunter method, this application uses _TiO2 as the titanium source to directly reduce the titanium sponge to prepare titanium sponge, which simplifies the preparation process in the operation process, that is, the process of preparing _TiCl4 by chlorination of _TiO2 is omitted. ; At the same time, the use of harmful gas chlorine is avoided, which is in line with the concept of green production; finally, the titanium sponge product prepared by the method used in this application has a higher purity. In addition, for the preparation of titanium sponge by the direct reduction method of _TiO2 , compared with the several methods mentioned in the comparative example, the present application proposes a staged reduction method. The low-temperature segmental reduction helps to reduce energy consumption and obtain a coarse sponge. Titanium, deoxidation in the high temperature section can further remove the oxygen in the sponge titanium, so as to achieve better product quality.

Claims (5)

1. A method for preparing metallic titanium powder by metallothermic reduction of titanium dioxide is characterized by comprising the following steps:

(1) Uniformly mixing titanium dioxide with the granularity of 100-1000 meshes and anhydrous calcium chloride according to the mass ratio of 1-3;

(2) Uniformly mixing magnesium oxide, calcium oxide and calcium carbide with the particle size range of 100-1000 meshes according to a mass ratio of 1;

(3) Placing the block II prepared in the step (2) in a molybdenum boat and in the lower layer of a graphite crucible, placing the block I prepared in the step (1) in the upper layer of the graphite crucible, separating the block I and the block II by a porous molybdenum plate, and covering a graphite cover above the graphite crucible;

(4) Heating the graphite crucible obtained in the step (3) to 800-1000 ℃ under the pressure intensity of less than 30Pa, and preserving the temperature for 180-360 min; then heating to 1100-1300 ℃, and preserving the temperature for 180-360 min to obtain reduced block materials;

(5) Stirring and leaching the blocky material obtained in the step (4) in a hydrochloric acid solution with the pH value of 0.5-1 for 4-8 hours, wherein the pH value of the solution is regulated to be always in the above range by dropwise adding 1mol/L hydrochloric acid solution in the stirring process, and the stirring speed is controlled to be 100-300 r/min;

(6) And (5) filtering and separating the material obtained in the step (5) to obtain leachate and solid, repeatedly washing the solid with deionized water and absolute ethyl alcohol until the filtrate is neutral, and drying the filter cake at 40-80 ℃ for 8-16 h to obtain the metal titanium powder.

2. The method of producing metallic titanium powder by metallothermic reduction of titanium dioxide as set forth in claim 1, wherein: the size of the block body I in the step (1) is phi 15 multiplied by 20 to phi 20 multiplied by 20mm.

3. The method of producing metallic titanium powder by metallothermic reduction of titanium dioxide as set forth in claim 1, wherein: the block II in the step (2) has the size of phi 15 multiplied by 10-phi 20 multiplied by 10mm.

4. The method of producing metallic titanium powder by metallothermic reduction of titanium dioxide as set forth in claim 1, wherein: the heating rate in the step (4) is 10 ℃/min.

5. The method of producing metallic titanium powder by metallothermic reduction of titanium dioxide as set forth in claim 1, wherein: the liquid-solid ratio in the agitation leaching in the step (5) is more than 15.

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