RU2385837C2 - Method of producing titanium hydride and device for realising said method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used in production of titanium hydride used in nuclear power engineering, in chemical and other industries. The method of producing titanium hydride involves reacting spongy titanium with hydrogen inside a sealed water-cooled reactor under hydrogen pressure in combustion mode through local initiation of the combustion process with subsequent self-propagating high-temperature synthesis, cooling of the synthesis product and its extraction. Hydrogen is fed into the reactor from the top through a valve fitted on a pipe running to the cover of the reactor. The initiation process is carried out at initial hydrogen pressure less than 0.5 MPa. The self-propagating high-temperature synthesis process is carried out at constant hydrogen pressure less than 0.3 MPa using a flame or a closed hydrogen cooling system. Spongy titanium screenings of the -4+2 mm fraction are used to initiate the combustion process. A device for producing titanium hydride is proposed.

EFFECT: invention simplifies the method and design of the device for producing titanium hydride, increases efficiency and quality of the obtained product.

3 cl, 1 dwg, 1 tbl, 2 ex

Description

The invention relates to the field of inorganic chemistry and powder metallurgy, and in particular to a method for producing titanium hydride in a combustion mode and a device for implementing the method.

Titanium hydride can be used in various fields of technology, the main of which are nuclear energy (as moderators in the control rod of a fast fast neutron reactor, as a filler in a paste-like material to protect against radioactive radiation); as a starting material for obtaining highly pure titanium powder; as an additive for the production of porous and diamond-containing composite material in the mode of self-propagating high-temperature synthesis (SHS); as a source of hydrogen; as a moisture absorber; as an additive in termite and igniter compositions; during heat treatment of parts, for example, in the watch industry and in other areas.

A known method of producing hydrides of transition metals, in particular titanium hydride, which includes pressing a polydispersed titanium powder with a dispersion of 0.5-1.5 mm (500-1500 μm) in the form of tablets, placement in a sealed water-cooled reactor, vacuuming the reactor to 10 ^-1 mm Hg, filling the reactor with hydrogen to a pressure of 1-5 atm (0.1-0.5 MPa), local initiation with a tungsten wire in contact with the metal, subsequent passage of self-propagating high-temperature synthesis and extraction of the finished product Recreatives Products (SU 552 293, C01G 1/00, 30.03.1977).

The known method allows to obtain titanium hydride containing 4.04 wt.% Hydrogen, which corresponds to the calculated composition of TiH ₂ with a face-centered cubic lattice of the CaF ₂ type with a lattice period of 4.454 Å.

The main disadvantage of this method is its low productivity (not more than 0.5 kg per experiment) and a fairly high cost. In addition, the synthesis product is a highly sintered material and requires additional grinding. For example, to obtain a powder with a fineness of less than 150 microns, grinding in a ball mill for 10 hours is required.

The closest solution to the claimed one is a method for producing titanium hydride, which involves the interaction of titanium with hydrogen in the reaction volume of a water-cooled pressurized reactor under hydrogen pressure in the combustion mode by local initiation of the process of ignition of titanium with subsequent passage of self-propagating high-temperature synthesis, cooling the synthesis product and its isolation, when this is used as titanium sponge titanium powder or a mixture thereof with a polydisperse titanium powder, which they are taken predominantly in an amount of not more than 50% by weight of titanium sponge, the process is carried out at an initial hydrogen pressure of at least 2 MPa, the process of self-propagating high-temperature synthesis is carried out under a constant hydrogen pressure of at least 0.3 MPa with additional cooling of the synthesis product mainly in a stream of hydrogen (RU 2208573 C1, January 23, 2002). Sponge titanium is used in the form of powders of fractions -100 + 12, or -70 + 12, or -12 + 5, or -12 + 2, or -5 + 2 mm, or in the form of mixtures of these fractions in any ratio, or mixture, at least one of the fineness indicated with polydispersed titanium powder is -5 + 1.5 mm, preferably not less than 1.8 mm. Sponge titanium can be used in the form of briquettes tightly filling the reaction volume. In some cases, when the target product is cooled, not more than 50 vol.% Argon or carbon monoxide can be introduced into hydrogen.

The said patent describes a device for producing titanium hydride, which contains a housing, a cover, a water-cooled jacket, a pipeline for supplying hydrogen, shut-off valves: the lower one for hydrogen inlet and the upper one for hydrogen release, a manometer (mono-vacuum gauge) for monitoring gas pressure, electric inputs for supplying current and initiating the combustion process, a cylindrical reaction glass with titanium installed in the reactor, the glass bottom being gas-permeable, raised from the edge by 5-10 mm and sealed with the bottom of the ring reactor oh gasket.

The main disadvantages of the known method and device include the following. Mixing a titanium sponge and a polydisperse titanium powder of 10-50% affects the quality of the hydride obtained due to the low quality of the polydisperse powder, which contains up to at least 1 wt.% Impurities in the form of iron, silicon, oxygen, hydrogen. Typically, the titanium content of the powders is less than 99%, and the titanium content of the sponge is at least 99.64%. In addition, mixing powders with a sponge is an additional technological operation that requires special equipment and time.

Another disadvantage of this method is the supply of hydrogen to the reaction volume of the reactor from below, and its exit from above through a valve mounted on the lid pipeline. This greatly complicates the cooling of the upper part of the reactor and the lid and requires additional structural solutions to the cooling method.

A disadvantage of the known device is the use of a cylindrical reaction beaker. It is known that the density of titanium is higher than the density of titanium hydride by more than 16%, that is, during synthesis there is an increase in the volume of the obtained product and, accordingly, it is jammed in a cylindrical glass, which makes unloading difficult.

All these disadvantages lead to an increase in the cost of the target product and a decrease in the efficiency of the process as a whole.

The technical task of the invention is to reduce the cost of the target product, increase productivity, efficiency and safety of the process, simplify the method and design of the device, improve the quality of the resulting product.

The problem is achieved in that the method for producing titanium hydride involves the interaction of titanium sponge with hydrogen in the reaction volume of a pressurized water-cooled reactor under hydrogen pressure by local initiation of the combustion process followed by self-propagating high-temperature synthesis, cooling the synthesis product and its evolution, according to the invention, hydrogen is fed into the reactor from above through a valve mounted on the inlet pipe to the reactor lid, the initiation process is conducted at an initial hydrogen pressure of less than 0.5 MPa, the process is self-propagating high synthesis is carried out at a constant hydrogen pressure of less than 0.3 MPa using a hydrogen torch or a closed cooling system, and to initiate the combustion process are used spongy titanium screenings fraction -4 + 2 mm.

A device for producing titanium hydride includes a water-cooled reactor vessel with a lid, a reaction cup with a grate bottom filled with sponge titanium and mounted on an annular gasket, electric inputs for supplying current and initiating the combustion process, a valve for supplying hydrogen, a vacuum pump, a torch, and a means for monitoring pressure hydrogen, according to the invention, the means for controlling pressure is a manovacuum meter, the reaction beaker is made in the form of a cone expanding at the top, with a taper in the range 1: 50-1: 25, while the device is equipped with a means for supplying hydrogen through a valve located on the inlet pipe to the reactor cover located on top and a pipe for hydrogen output located at the bottom and connected to a vacuum pump with a valve, a vacuum gauge and a torch with a valve and an ignition coil connected to the base of the reactor, and as a ring gasket material, asbestos board or asbestos fabric is used.

The drawing shows a schematic diagram of a device for implementing the method of producing titanium hydride.

The device comprises a reactor vessel 1; cover 2; water-cooled shirt 3; a conical reaction cup 4 with a trellised bottom 5 filled with sponge titanium powder 6 mounted on an annular gasket 7; electrical inputs 8 for the initiating spiral; a vacuum valve 9 for supplying hydrogen to the reactor; a vacuum pump 10 with a vacuum valve for evacuating the reactor; torch control valve 11; exhaust hood 12; torch with a spiral of 13; control vacuum gauge 14.

All parts of the reactor, reaction cup, inlet and outlet pipelines are made of heat-resistant and chemically resistant steel type 12X18H10T. For ring gasket 7, asbestos board or asbestos fabric is used.

The volume of the reactor, depending on the task, is 2, 5; 8; 20 and 30 liters, loading into the reactor 30 liters is 30 kg of sponge titanium.

The onset of the combustion reaction is determined by the pressure drop from the initial to the hydrogenation process. To organize the flow of hydrogen through the reaction volume, a torch is used for cooling (for reactors of 8 l or less), and for reactors of large volumes of 20 or 30 l, a closed cooling system is used. The hydrogen exiting the reactor is cooled and sent back to the reactor. Hydrogen is supplied to the reactor, which is located vertically, through the top valve installed on the inlet pipe to the reactor cover, and the hydrogen leaves the reactor from below through a pipe leaving the reactor, which is connected to a vacuum system, to a control system, to a torch, or to a cooling system hydrogen (for reactors of large volumes instead of a torch).

A closed reactor cooling system can be carried out in several ways, for example by pumping by a compressor, or by pre-collecting hydrogen into a receiver with lower pressure, and then pumping the compressor to the desired pressure.

A method of producing titanium hydride using the specified device is as follows. The reaction conical beaker 4 is filled with sponge titanium powder 6. The reactor vessel 1 is fixed in a vertical position, the beaker 4 is lowered onto an annular sealing gasket 7 made of asbestos cardboard or fabric. An initiating spiral is fixed to the electrical inputs 8, usually a nichrome wire with a diameter of 0.2-0.5 mm. In the contact zone of the spiral with titanium, fine screenings of the powder of the fraction -4 + 2 mm are added. The reactor is closed with a lid 2, sealed and vacuum pump 10, opening the valve of the vacuum pump, control is carried out by the vacuum gauge 14. After vacuum, the vacuum valve is closed, the pump is turned off and the reactor is filled with hydrogen to a pressure of less than 0.5 MPa, opening valve 9 installed on the inlet pipe to the reactor lid. In a water-cooled jacket 3 serves water to cool the reactor vessel. An electrical impulse is supplied to the electrical inputs 8 with an initiating spiral. The beginning of the combustion process in the reactor is controlled by the pressure drop on the manovacuum meter 14, which occurs rather quickly due to the beginning of the interaction of titanium with hydrogen. When a pressure of less than 0.3 MPa is reached, the hydrogen supply valve 9 is opened, while the hydrogen reducer is adjusted to a pressure of less than 0.3 MPa.

To increase the completeness of the conversion of titanium to hydride, as well as to create cooling conditions for the upper part of the reactor and the lid, a torch 13 is lit, which is installed under an exhaust hood 12. The torch is equipped with an open electric coil, which is heated to a temperature of 500-600 ° C (voltage is regulated by an autotransformer until a dark red glow appears on the spiral), turning the spiral on and off is blocked with cooling the reactor. The inclusion of the torch and its height is regulated by a needle valve 11.

During the process of hydrogenation of titanium sponge, the gas pressure in the reactor is constantly monitored, the temperature of the cooling water discharged from the reactor, and the behavior of the torch. The duration of the process is determined by the volume of the reactor. For a reactor with a beaker diameter of up to 80 mm, the process takes up to 30 minutes, and with a beaker diameter of 200 mm, the process takes 150 minutes. These data are for the hydrogenation of titanium TG-100, fractions -12 + 2 mm.

After the end of the combustion process (determined by the end of the pressure drop in the reactor when valves 9 and 11 are closed) and after the cooling of the reactor (determined by the low temperature of the drained water from the reactor), the hydrogen pressure in the reactor is reduced to atmospheric. Hydrogen pressure is reduced by torch 13 with valve 9 closed. After pumping out the remaining hydrogen from the reactor with pump 10, the system is filled (purged) with nitrogen or an inert gas, the reactor is opened, and the synthesis product is recovered.

In the inventive method, titanium sponge is used in accordance with GOST 17746-96 grades from TG-90 to TG-120. Sponge titanium of these grades is the purest, the oxygen content in it is not more than 0.06% with a titanium content of not less than 99.64%. Hydrogen is used according to TU 6-20-00209585-26-97, purified from oxygen and moisture, containing not more than 0.01 vol.% Impurities of oxygen and argon.

The essence of the method is illustrated by examples.

Example 1

Take spongy titanium powder TG-110, fractions -12 + 2 mm, place it in a conical reaction cup 4 with a taper of 1:25, the bottom of which is made gas permeable due to holes with a diameter of 1.0 mm. The beaker is placed in a 2.5 liter reactor. An initiating spiral of nichrome wire with a diameter of 0.2-0.5 mm is fixed on the electrodes 8. In the contact zone of the helix with titanium 4, fine screenings of titanium of sponge fraction of -4 + 2 mm in an amount of at least 10 g are added. The reactor is closed with lid 2, sealed and vacuum to a pressure of 10 mm Hg. Through the upper valve 9, hydrogen is supplied to the reactor to an initial pressure of 0.45 MPa. Before initiation, the valve 9 is closed, water is supplied to the water-cooled jacket 3, combustion is initiated by applying a current pulse to the spiral.

The onset of combustion is monitored on a manovacuum meter 14 to reduce the pressure of hydrogen in the reactor due to the beginning of the interaction of titanium with hydrogen. With the beginning of the pressure drop, the valve 9 is opened and the pressure in the reactor is set at 0.25 MPa by means of a gas reducer. After making sure that the spiral on the torch is heated, open valve 11, providing a flow of hydrogen along the entire length of the reaction beaker.

The end of the combustion process and the subsequent cooling of the reactor are controlled by stopping the pressure drop in the reactor when valves 9 and 11 are closed, as well as by the temperature of the water discharged from the reactor. Water temperature should not be higher than room temperature.

After cooling the reactor, the hydrogen pressure in it is reduced to atmospheric. Complete removal of hydrogen from the gas systems of the reactor is carried out by afterburning in a flare, followed by pumping out the remaining hydrogen by a vacuum pump and filling (flushing) with an inert gas. Then the reactor is opened and the synthesis product is recovered.

The target product is titanium hydride in the form of a hydrogenated sponge, which is easily discharged from a conical reaction beaker and easily crushed in a mortar (grinding time does not exceed 30 minutes).

According to x-ray phase analysis, the synthesis product is titanium hydride with a face-centered cubic lattice of the Fm3m type. According to chemical analysis, the product contains 4.02 wt.% Hydrogen, which corresponds to the formula TiH ₂ .

Example 2

Take sponge titanium TG-100 of two fractions -70 + 12 mm and -12 + 2 mm, place the mixture in a conical reaction cup 4, designed for a reactor with a volume of 30 liters. The glass has a taper of 1:50 and a gas-permeable bottom 5. A large sponge (-70 + 12 mm) is loaded 90% of the volume down the glass, then a small sponge (-12 + 2 mm) is poured onto the top 10% of the volume. The total load weight is 30 kg. The glass is lowered into the reactor and mounted on an annular gasket made of asbestos fabric. An annular gasket provides a seal of the base of the reaction cup with the bottom of the reactor and creates the conditions for the passage of hydrogen through a titanium sponge, provides a complete conversion and the possibility of cooling after the combustion reaction.

The initiating spiral is fixed on the electrodes 8, and in the zone of contact of the spiral with titanium sponge, titanium screenings of a fraction of -4 + 2 mm are poured for reliability of initiation.

The pressurization of the reactor, evacuation, the supply of hydrogen to the reactor, the cooling of the reactor vessel and the initiation are carried out according to example 1. The reactor is filled with hydrogen to an initial pressure of 0.3 MPa. After the initiation of the combustion reaction, the hydrogen pressure in the reactor is reduced to 0.15 MPa and maintained throughout the combustion time.

The total cycle time (combustion and cooling) in a 30-liter reactor is up to 3 hours. In order to reduce the cooling time and intensify the hydrogenation process, most of the "spent" hydrogen is sent not to the flare, but again to the reactor after preliminary cooling. In this case, the cycle time is not more than 1.5 hours.

The target product is easily unloaded from a conical reaction beaker and easily crushed to a dispersion of 150 μm in a ball mill for 30 minutes (in the prototype for 2 hours). According to x-ray phase analysis, the synthesis product is titanium hydride. The data of chemical analyzes of the synthesis product are presented in the table.

Thus, the claimed combination of features of the claims allows to simplify the process of producing titanium hydride, to increase the purity of the target product, its cost by using the design of the glass and by reducing the grinding time, to increase the efficiency of the process and its fire safety.

Table No. p / p Sponge titanium The volume of the reactor, l The weight of the charge, kg Pressure, MPa Cycle time min Cooling Mode *) Results chem. analysis of TiH ₂ , wt.% Mark Charge fraction, mm Filling fraction, mm Initial In synthesis Hz 02 Fe one. TG-110 -12 + 2 -4 + 2 2.5 2,4 0.45 0.25 thirty Torch 4.02 0.04 0.06 2. TG-100 -70 + 12 / -12 + 2 = 90/10 -4 + 2 30,0 30,0 0.3 0.15 90 H ₂ cooling 4.04 0.05 0.06 3. TG-100 -12 + 2 -4 + 2 8.0 7.6 0.40 0.20 45 Torch 4.03 0.05 0.06 four. TG-120 -12 + 2 -4 + 2 20,0 19.5 0.35 0.25 90 Torch 4.03 0.05 0.06 5. TG-100 -12 + 2 -4 + 2 20,0 19,4 0.30 0.15 75 H ₂ cool 4.04 0.04 0.06 6 ** TG-120 -12 + 2 - 30,0 30,0 2.0 0.10 150 H ₂ cool 4.04 0.06 0,07 *) H ₂ cooling - closed cooling system (spent hydrogen after cooling is again sent to the reactor in order to cool the reaction mixture). **) - prototype.

Claims (3)

1. A method of producing titanium hydride, including the interaction of titanium sponge with hydrogen in the reaction volume of a pressurized water-cooled reactor under hydrogen pressure in the combustion mode by local initiation of the combustion process followed by the passage of self-propagating high-temperature synthesis, cooling the synthesis product and its evolution, characterized in that hydrogen in the reactor enters from above through a valve installed on the supply pipe to the reactor lid, the initiation process is carried out at the initial om hydrogen pressure of less than 0.5 MPa, the process is self-propagating high synthesis is carried out at a constant hydrogen pressure of less than 0.3 MPa using a hydrogen torch or a closed cooling system, and to initiate the combustion process are used spongy titanium screenings fraction -4 + 2 mm. 2. A device for producing titanium hydride, including a water-cooled reactor vessel with a lid, a reaction cup with a grate bottom, filled with sponge titanium and mounted on an annular gasket, electric inputs for supplying current and initiating the combustion process, a valve for supplying hydrogen, a vacuum pump, a torch, a tool for monitoring the pressure of hydrogen, characterized in that the means for controlling the pressure is a manovacuum meter, the reaction cup is made in the form of a cone expanding at the top, with a taper in the range 1: 50 ÷ 1: 25, pr This device is provided with an overhead means for feeding hydrogen through a valve in the supply line to the lid of the reactor and the conduit for the hydrogen exit located below and connected to a vacuum pump with a valve, manometers and torch to the valve and igniting coil connected to reactor base. 3. The device according to claim 2, characterized in that asbestos cardboard or asbestos fabric is used as the material of the annular gasket.

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