A method for producing a rare metal chloride

Abstract

The application discloses a preparation method of rare metal chloride, which comprises the following steps: in an inert atmosphere, a mixture containing rare metal powder, a chlorine salt and an auxiliary material is heated to a predetermined temperature, oxygen is introduced, the concentration of oxygen in the mixed gas is adjusted, a chlorination reaction is carried out, and a chlorination product is condensed and collected to obtain the rare metal chloride. The application avoids the safety production risk caused by the use of chlorine or hydrogen chloride in the traditional production, and the production process avoids the leakage risk of liquid chlorine and compressed hydrogen chloride in the storage and transportation process. Since the reaction process is a double decomposition reaction, the reaction rate is controllable, the reaction does not have obvious heat release, and is safe and reliable. The chlorine content in the production tail gas is extremely low, and the environmental pollution problem caused by a large amount of chlorine-containing tail gas in the traditional chlorination process is avoided.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical materials technology, and particularly relates to a method for preparing rare metal chlorides. Background Technology

[0002] Rare metal chlorides are a special class of molecular crystalline compounds that serve as fundamental chemical materials in fields such as pharmaceutical catalysts, metal vapor deposition materials, and high-end plastic additives. They have a wide range of applications and a promising market prospect. In particular, with the explosive growth of industries such as artificial intelligence and new energy power components, the application of rare metal chlorides in ultra-high temperature coatings and chip surface vapor deposition (CVD / PVD) is receiving increasing attention, with their application scope expanding and demand gradually increasing.

[0003] Conventional chlorination processes typically use chlorine gas or hydrogen chloride as the chlorine source, both of which are hazardous chemicals and highly irritating to living organisms. Contact with or inhalation can easily lead to poisoning and other safety accidents. The transfer, transportation, and storage of liquid chlorine and compressed hydrogen chloride all pose safety hazards, with the possibility of leakage. Leaks can easily occur during the chlorination process due to defects in the gas delivery system or equipment damage, threatening the lives of operators and causing serious safety accidents. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above and provide a safe and environmentally friendly method for preparing rare metal chlorides.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A method for preparing rare metal chlorides includes the following steps:

[0007] In an inert atmosphere, a mixture containing rare metal powder, chloride salt and auxiliary materials is heated to a predetermined temperature, oxygen is introduced and the concentration of oxygen in the mixed gas is adjusted to carry out a chlorination reaction, and the chlorination product is condensed and collected to obtain the rare metal chloride.

[0008] The predetermined temperature is 300–600°C;

[0009] The oxygen concentration in the mixed gas is 70% to 95%.

[0010] The auxiliary material is used to inhibit the oxidation of elemental metals in oxygen.

[0011] As a further improvement, the rare metals include tungsten, molybdenum, tantalum, niobium, hafnium, zirconium, or rhenium.

[0012] As a further improvement, the chloride salt includes one or any combination of sodium chloride, calcium chloride, magnesium chloride, or aluminum chloride.

[0013] As a further improvement, the ratio of the rare metal to the chloride salt is such that the chloride salt is in excess by 10% to 30% based on the stoichiometric ratio of the reaction.

[0014] As a further improvement, the auxiliary materials include one or any combination of high-purity graphite powder, coke powder, or wood charcoal powder.

[0015] As a further improvement, the proportion of the auxiliary material added is 1 to 5% of the total mass of the rare metal and chloride salt mixture.

[0016] As a further improvement, the inert atmosphere is argon or nitrogen or a mixture thereof.

[0017] As a further improvement, the chlorinated product is carried by the airflow into a constant temperature receiver, the temperature of which is 10-50°C.

[0018] This invention uses chloride salts such as sodium chloride, calcium chloride, and magnesium chloride as chlorine sources. Through high-temperature reaction, the chlorine components in the chloride salts are decomposed and separated, and then combined with rare metal powders to form rare metal chlorides. Taking tantalum pentachloride and niobium pentachloride as examples, the main chemical reaction equations are as follows:

[0019] Ta+5NaCl+1.25O2=TaCl5+2.5Na2O

[0020] Nb+2.5MgCl2+1.25O2=NbCl5+2.5MgO

[0021] Compared to the traditional gas-solid reaction of chlorine or hydrogen chloride, this method is a double displacement reaction of molten salt system. By controlling the input of oxygen, the reaction rate can be adjusted. There is no chlorine or hydrogen chloride involved in the entire process. In case of equipment malfunction, the oxygen supply can be stopped and the heating system can be shut down to cut off the reaction process and avoid safety risks.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. Avoid the safety risks associated with the use of chlorine or hydrogen chloride in traditional production, and avoid the risk of leakage of liquid chlorine and compressed hydrogen chloride during storage and transportation during the production process;

[0024] 2. Since the reaction process is a double displacement reaction, the reaction rate is controllable, the reaction does not have obvious exothermic effects, and it is safe and reliable;

[0025] 3. The chlorine content in the production exhaust gas is extremely low, avoiding the environmental pollution problems caused by the large amount of chlorine-containing exhaust gas in traditional chlorination processes;

[0026] 4. Auxiliary materials protect the elemental metal from oxidation by oxygen, thereby obtaining high-purity rare metal chlorides. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is the XRD diffraction pattern of tantalum pentachloride product from Example 1;

[0029] Figure 2 This is a photograph of the tantalum pentachloride product from Example 1;

[0030] Figure 3 This is the XRD diffraction pattern of the niobium pentachloride product from Example 2;

[0031] Figure 4 This is a photograph of the niobium pentachloride product from Example 2. Detailed Implementation

[0032] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0033] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0035] The method for preparing high-purity rare metal chlorides by reduction chlorination according to some specific embodiments of the present invention includes the following steps:

[0036] In an inert atmosphere, a mixture containing rare metal powder and chloride salt is heated to a predetermined temperature, oxygen is introduced, and the concentration of oxygen in the mixed gas is adjusted to a certain range to carry out a chlorination reaction. The chlorination product is then condensed and collected.

[0037] In some embodiments, the inert atmosphere may be argon or nitrogen and a mixture thereof.

[0038] In some embodiments, the rare metals include, but are not limited to, tungsten, molybdenum, tantalum, niobium, hafnium, zirconium, and rhenium.

[0039] In some embodiments, the chloride salt includes, but is not limited to, sodium chloride, calcium chloride, magnesium chloride, aluminum chloride, etc. The ratio of rare metal to chloride salt is 10% to 30% excess chloride salt based on the stoichiometric ratio of the reaction.

[0040] In some embodiments, the mixture further includes auxiliary materials, including but not limited to high-purity graphite powder, coke powder, and charcoal powder. These auxiliary materials inhibit the oxidation of the elemental metal in oxygen, thereby increasing the chlorination rate of the product. Preferably, the proportion of the auxiliary materials added is 1-5% of the total mass of the rare metal and chloride salt mixture.

[0041] In some embodiments, the predetermined temperature is 300-600°C, preferably 300-500°C. If the temperature is too low, the reaction rate will be low, and if the temperature is too high, it will promote the oxidation of the metal and reduce the reaction yield. At the same time, if the temperature is too high, the chloride will easily clump on the wall of the receiver, causing inconvenience to the subsequent use of the chloride powder.

[0042] In some embodiments, the oxygen concentration in the mixed gas is 70% to 95% (by volume), preferably 80% to 90%. Too low an oxygen concentration will reduce the reaction rate, while too high an oxygen concentration will promote metal oxidation and reduce the reaction yield.

[0043] During the reaction, the chlorinated product is carried by the gas flow into a collector (preferably a constant-temperature collector) for condensation and collection. In some embodiments, the collector is kept at a constant temperature of 10–50°C. The tail gas enters a tail gas absorption device. The collected product must be removed in an oxygen-free environment.

[0044] In some embodiments, a traditional horizontal tube furnace can be used as the reaction equipment, and the reaction device is made of high-purity quartz to ensure product purity.

[0045] In order to achieve chlorine-free and safe production of metal chlorides and avoid the safety risks associated with the use of chlorine or hydrogen chloride in traditional production, this invention proposes the idea of ​​chloride salt chlorination separation. This not only makes the chlorination process safe and controllable, but also simplifies the process and equipment, making it suitable for industrial application.

[0046] Example 1

[0047] 1000g of tantalum powder, 1776g of analytical grade sodium chloride (10% excess), and 28g of high-purity graphite powder (approximately 1% of the total weight of the tantalum powder and sodium chloride mixture) were mixed evenly and dried to constant weight in an oven at 110℃. The dried material was loaded into a quartz boat, which was then placed in a tube furnace. Argon gas was introduced at a flow rate of 0.2L / min, and the reaction temperature was set to 500℃. When the furnace temperature reached 500℃, the argon gas flow rate was reduced to 0.1L / min, the oxygen flow rate was adjusted to 0.8L / min, and the water bath temperature of the collector was set to 15℃ until the reaction was complete. A total of 1922g of tantalum pentachloride powder was obtained, with a yield of 97%. A very small amount of product adhered to the wall and could not be collected. The remaining product, including residual reactants, totaled 1063g. Figure 1 and Figure 2 The images show the XRD diffraction pattern and physical image of the prepared tantalum pentachloride product. The trace element analysis results for the TaCl5 product are as follows: purity exceeds 99.99%.

[0048] Table 1. Trace element analysis of tantalum pentachloride (ppm)

[0049] element content K ＜0.5 Na 12 S 0.25 Si 20 Li ＜0.05 Be ＜0.01 B 0.02 Al 0.12 Ti 3.3 V ＜0.01 Cr 0.2 Mn ＜0.5 Fe 6

[0050] Example 2:

[0051] 1000g of niobium powder, 3330g of analytical grade magnesium chloride (30% excess), and 217g of high-purity graphite powder (approximately 5% of the total weight of the niobium powder and magnesium chloride mixture) were mixed evenly and dried to constant weight in an oven at 110℃. The dried material was loaded into a quartz boat, which was then placed in a tube furnace. Argon gas was introduced at a flow rate of 0.3L / min, and the reaction temperature was set to 300℃. When the furnace temperature reached 300℃, the argon gas flow rate was reduced to 0.1L / min, the oxygen flow rate was adjusted to 0.6L / min, and the water bath temperature of the collector was set to 50℃ until the reaction was complete. A total of 2810g of niobium pentachloride powder was obtained, with a yield of 96.63%, and the total product plus residual reactants amounted to 1862g. Figure 3 and Figure 4 The images show the XRD diffraction pattern and physical image of the prepared niobium pentachloride product. The trace element analysis results for NbCl5 are as follows: the product purity reaches 99.99%.

[0052] Table 2. Trace element analysis of niobium pentachloride (ppm)

[0053] element content Ca 6.77 Mg 18.01 S 0.32 Si 5.89 Li 32.2 Be 14.2 B 3.62 Al 4.79 Ti 2.80 V 6.31 Cr 1.33 Mn 1.11 Fe 11.84

[0054] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing rare metal chlorides, characterized in that, Includes the following steps: In an inert atmosphere, a mixture containing rare metal powder, chloride salt and auxiliary materials is heated to a predetermined temperature, oxygen is introduced and the concentration of oxygen in the mixed gas is adjusted to carry out a chlorination reaction, and the chlorination product is condensed and collected to obtain the rare metal chloride. The rare metals mentioned are tungsten, molybdenum, tantalum, niobium, hafnium, zirconium, or rhenium; The chloride salts mentioned include one or any combination of sodium chloride, calcium chloride, magnesium chloride, or aluminum chloride; The predetermined temperature is 300~600℃; The oxygen concentration in the gas mixture is 70% to 95% by volume. The auxiliary materials include one or any combination of high-purity graphite powder, coke powder, or wood charcoal powder, and are used to inhibit the oxidation of elemental metals in oxygen.

2. The method for preparing rare metal chlorides according to claim 1, characterized in that, The ratio of the rare metal to the chloride salt is based on the stoichiometric ratio of the reaction, with the chloride salt in excess by 10% to 30%.

3. The method for preparing rare metal chlorides according to claim 1, characterized in that, The auxiliary materials are added at a ratio of 1 to 5% of the total mass of the rare metal and chloride salt mixture.

4. The method for preparing rare metal chlorides according to any one of claims 1 to 3, characterized in that, The inert atmosphere is argon, nitrogen, or a mixture thereof.

5. The method for preparing rare metal chlorides according to any one of claims 1 to 3, characterized in that, The chlorinated product is carried by the airflow into a constant temperature receiver, which is maintained at a temperature of 10~50℃.

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