JP2010013686A - Method for producing sponge titanium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent the blockage from occurring in a melt-transportation pipe during a tapping operation in a process of producing sponge titanium with the Kroll method, through a simple operation. <P>SOLUTION: This production method includes lowering the level of a melt in a melt-transportation pipe 13 which is a vertical pipe, down to an opening end of the melt-transportation pipe 13 in a bottom side of a reduction reaction vessel 10 by injecting a gas into the melt-transportation pipe 13, prior to the tapping operation of extracting molten MgCl<SB>2</SB>produced as a byproduct from the bottom part of the vessel 10 to the outside of the vessel 10 through the vertical melt-transportation pipe 13, in a middle of the reaction. The melt in the melt-transportation pipe 13 is pressed into the reduction reaction vessel 10, and the molten Mg in the melt floats on the molten MgCl<SB>2</SB>in the reduction reaction vessel 10 due to a difference between the specific gravities. Afterward, the molten MgCl<SB>2</SB>is extracted from the bottom part of the reduction reaction vessel 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing sponge titanium by a crawl method.

  Titanium metal for wrought material used as an aircraft material or the like is manufactured through processes such as manufacture of sponge titanium by the crawl method, dissolution and solidification of sponge titanium (production of titanium ingot), and the like. In the production of sponge titanium by the crawl method, a reduction reaction vessel 10 called a retort is used as shown in FIG. The reduction reaction vessel 10 is made of stainless steel or the like having excellent heat resistance, and includes a titanium tetrachloride supply pipe 11 and an inert gas supply pipe 12 attached to the upper lid, a melt transport pipe 13 connected to the bottom, and the like. It has.

  The melt transport pipe 13 here is an external vertical pipe arranged vertically beside the reduction reaction vessel 10, and its lower end is a bottom of the vessel for extracting by-products accumulated in the bottom of the vessel during the reaction. It is connected to the. The upper end portion of the melt transport pipe 13 has a flange structure for connection to other melt transport pipes, attachment of a cover plate, and the like.

In operation, liquid titanium tetrachloride is supplied from the titanium tetrachloride supply pipe 11 into the container in a state where the reduction reaction container 10 installed in the furnace is filled with molten Mg50 and the remaining space in the container is filled with Ar gas. Dripping. Titanium tetrachloride dropped into the container is sequentially reduced by the molten Mg 50 in the container, whereby sponge titanium 60 is generated in the container. As the titanium sponge 60 is produced, liquid MgCl ₂ 70 is by-produced. By-product MgCl ₂ 70 accumulates in the bottom of the reduction reaction vessel 10 due to the difference in specific gravity.

As the by-product MgCl ₂ 70 accumulates in the container, the generation efficiency of the sponge titanium 60 is lowered. In order to prevent this, by-product MgCl ₂ 70 is extracted from the reduction reaction vessel 10 during the operation (Patent Document 1). This operation is called tapping and is repeated many times during operation. The details of this tap operation are as follows.

JP 2004-292932 A

  The mobile recovery container 20 is placed next to the reduction reaction container 10. The collection container 20 has an introduction pipe 21 vertically attached to the upper part. The introduction pipe 21 is a melt transport pipe, and the upper end portion has a flange structure for connection with other melt transport pipes. When the recovery container 20 is placed on the reduction reaction container 10, the upper end of the introduction pipe 21 and the upper end of the melt transport pipe 13 are connected by the connection pipe 30. The connection pipe 30 is also a melt transport pipe similar to the melt transport pipe 13 and the introduction pipe 21, and both ends thereof are flange-coupled to the pipe ends of the respective melt transport pipes.

When the connection between the recovery container 20 and the reduction reaction container 10 is completed, Ar gas is pressed into the container from the inert gas supply pipe 12 of the reduction reaction container 10. As a result, MgCl ₂ 70 accumulated at the bottom of the reduction reaction vessel 10 is discharged into the recovery vessel 20 through the melt transport pipe 13, the connection pipe 30 that is also a melt transport pipe, and the introduction pipe 21. For efficient discharge, the lower end of the melt transport pipe 13 is connected to the lowermost part of the outer peripheral surface.

  By repeating this operation during operation, the reaction between titanium tetrachloride and molten Mg 50 proceeds smoothly in the reduction reaction vessel 10.

In the production of sponge titanium by the crawl method, in addition to the tap described above, an operation called additional charge may be performed. The additional charge is an operation for replenishing molten Mg50 during operation. When MgCl ₂ which is a by-product is extracted during operation, the space in the reduction reaction vessel 10 is increased. This is an operation aimed at increasing the amount of titanium sponge produced. Details of this operation will be described with reference to FIG.

  At the time of additional charging, the connecting pipe 30 shown in FIG. 3A is removed and the collection container 20 is moved away. Instead, the mobile Mg container 40 is placed next to the reduction reaction container 10. The Mg container 40 contains molten Mg 50 therein, and is equipped with a vertical inert gas supply pipe 41 and a Mg discharge pipe 42 attached to the upper part. The upper part of the Mg discharge pipe 42 has the same vertical pipe shape as the introduction pipe 21 of the recovery container 20 in order to share the connection pipe 30, and the lower part reaches the bottom of the Mg container 40 to lead out the molten Mg 50. Yes.

  When the Mg container 40 is fixed in place, the Mg discharge pipe 42 and the melt transport pipe 13 are connected by the connection pipe 30. In this state, Ar gas is injected into the Mg container 40 from the inert gas supply pipe 41. Thereby, molten Mg 50 in the Mg container 40 is injected into the reduction reaction container 10 through the discharge pipe 42 and the melt transport pipe 13.

  By repeating the tap and additional charge, the yield of titanium sponge 60 per batch is improved. For example, in the case of a reaction of 100 hours, the number of additional charges is several times for a dozen tap operations.

  One of the problems in the production of titanium sponge by such a crawl method is the blockage of the melt transport pipe in the tap operation described above. Specifically, the clogging occurs in the connection pipe 30 or in the upper part of the melt transport pipe 13 in the reduction reaction vessel 10 during the tap operation. Once the melt transport pipe is clogged, replacement work, heating and melting work, etc. are required, and work efficiency is significantly reduced. Although it may be possible to prevent clogging by forcibly heating the melt transport pipe, this measure is costly and is not a realistic measure.

  The objective of this invention is providing the sponge titanium manufacturing method which can prevent effectively the obstruction | occlusion of the melt transport pipe | tube by a tap operation by simple operation.

  The present inventor is engaged in the production of sponge titanium by the crawl method. In the process, the inventors have empirically recognized the following fact regarding the blockage of the transport pipe in the tap operation.

The operation in which the additional charge is performed is higher in the operation of performing the additional charge than the operation in which the additional charge of molten Mg is not performed. More specifically, the transportation pipe is likely to be blocked by the tap operation after the additional charge is performed. Even in operations where no additional charge is performed, the transport pipe is blocked, which is often caused by the first tapping operation. According to the inventor's investigation, it was found that the clogging material in the transport pipe is mainly composed of Mg, not MgCl ₂ extracted by tapping.

From these empirical findings, the present inventor speculated that the cause of the clogging of the transport pipe in the tap operation was the molten Mg remaining in the melt transport pipe 13 of the reduction reaction vessel 10. That is, at the start of operation, the reduction reaction vessel 10 is filled with molten Mg, but at the same time, the melt transport pipe 13 is also filled with molten Mg. As the reaction proceeds, MgCl ₂ is produced as a by-product, but the specific gravity of molten MgCl ₂ is greater than the specific gravity of molten Mg, and the molten Mg in the melt transport pipe 13 is not replaced with molten MgCl ₂ . Even if molten MgCl ₂ enters the melt transport pipe 13, at least the vicinity of the liquid level in the transport pipe is occupied by the molten Mg. Similarly, after the additional charging, the melt transport pipe 13 is filled with molten Mg. As a result, at the time of the first tap or when performing a tap operation after an additional charge, molten Mg flows into the connection pipe 30 immediately after the start of extraction, adheres to the inner surface of the pipe, and solidifies to generate a blockage. Become.

The reason why molten Mg is more likely to cause clogging than molten MgCl ₂ is unclear, but is thought to be due to differences in physical properties such as thermal conductivity between the two.

As a result of comprehensively examining these facts, the present inventor reduced the melt in the melt transport pipe 13 by pressurizing the melt transport pipe 13 in the reverse direction with an inert gas before the tap operation. The conclusion was reached that pushing back into the reaction vessel 10 could be a rational and efficient measure. That is, when an inert gas is injected into the recovery container 20 connected to the reduction reaction container 10 during the tap operation, the melt in the melt transport pipe 13 is easily pushed back into the reduction reaction container 10 [FIG. 3 (a)]. Molten Mg in the melt pushed back into the reduction reaction vessel 10 has a lower specific gravity than the molten MgCl _{2 in} the reduction reaction vessel 10, and thus floats in the melt in the reduction reaction vessel 10. Thereafter, when the pressurization is stopped, only the molten MgCl ₂ having a large specific gravity accumulated in the bottom of the reduction reaction vessel 10 flows into the melt transport pipe 13, and the inside of the melt transport pipe 13 is completely replaced with the molten MgCl _2. Is done.

Thus, before the tapping operation, once the molten Mg in the melt transport pipe 13 is replaced with molten MgCl ₂ , blockage in a series of transport pipes such as the connection pipe 30 is prevented.

The method for producing sponge titanium according to the present invention has been completed on the basis of such knowledge, and is produced by holding molten Mg inside the reduction reaction vessel and reacting molten Mg with TiCl ₄ in the furnace. Then, in the titanium sponge production method in which molten MgCl _{2 as a} by-product is extracted from the bottom of the reduction reaction vessel to the outside of the reduction reaction vessel through the vertical tubular tube in the course of the reaction, it is reduced through the melt delivery tube. Before extracting the molten MgCl ₂ in the reaction vessel out of the reduction reaction vessel, pressurize the gas into the melt transport pipe to lower the melt liquid level in the melt transport pipe to the opening on the container bottom side of the melt transport pipe, Thereafter, molten MgCl ₂ is extracted.

In the titanium sponge production method of the present invention, before extracting molten MgCl ₂ in the reduction reaction vessel out of the reduction reaction vessel through the melt transfer tube, a gas is injected into the melt transfer tube to The melt liquid level is lowered to the container bottom side opening of the melt transport pipe. The melt pushed down in the melt transport pipe flows into the reduction reaction vessel, and if molten Mg is present in the melt, the molten Mg having a small specific gravity floats in the melt in the vessel. If the molten MgCl ₂ is extracted after this, even if the molten Mg is mixed in the melt in the melt transport pipe, the molten Mg is excluded from the melt transport pipe, thereby preventing discharge of the molten Mg. Thus, the transportation pipe is prevented from being blocked due to the discharge of molten Mg.

Via melt transfer tube was charged with molten Mg to a reduction reaction vessel, lowering the melt liquid surface of the melt transport tube to the container bottom side opening of the melt transport tube after the charge, the melt MgCl ₂ If extraction is performed, the molten Mg in the melt transport pipe is replaced with molten MgCl _{2 in} the tap operation after the additional charge is performed, and blockage of the transport pipe during the tap operation is prevented. In this respect, the method for producing sponge titanium according to the present invention is particularly effective for an operation in which an additional charge is performed during the reduction reaction. The additional charge of molten Mg, and the subsequent lowering of the melt in the melt transport pipe and the molten MgCl. _This is more effective for a sponge titanium manufacturing method in which the extraction of ₂ is repeated a plurality of times.

  When the melt in the transport pipe is pushed down by gas injection into the melt transport pipe of the reduction reaction container, the melt is injected into the reduction reaction container. Since the volume of the melt transport pipe is very small compared to the volume of the reduction reaction container, even if the melt in the melt transport pipe is injected into the reduction reaction container, the increase in the pressure in the container due to the injection is slight. . When the melt in the transport pipe is continuously pushed down and the liquid level of the melt falls to the opening at the bottom of the container, the gas injected into the melt transport pipe is blown out as a bubble into the melt in the reduction reaction container. As a result, the pressure in the reduction reaction vessel rapidly increases. By detecting this increase in the internal pressure of the vessel, it is possible to easily and accurately grasp the time when the liquid level of the melt has reached the opening on the bottom side of the vessel, so that when the pressure in the reduction reaction vessel suddenly increases, The press-fitting can be stopped.

  The method for press-fitting gas into the melt transport pipe will be described in detail in a later embodiment.

  The gas that is pressed into the melt transport tube must be free of moisture. However, if dry air or nitrogen gas enters the reduction reaction vessel during the reaction, the quality of the titanium sponge deteriorates, so these are not desirable gases. A desirable gas is an inert gas typified by Ar gas.

In the titanium sponge production method of the present invention, before the molten MgCl ₂ in the reduction reaction vessel is drawn out of the reduction reaction vessel through the melt transfer tube, a gas is injected into the melt transfer tube to melt the melt in the melt transfer tube. The molten liquid in the melt can be removed from the melt transport pipe by a simple operation of lowering the liquid level to the opening on the container bottom side of the melt transport pipe and returning it to the reduction reaction container. Blockage of the object transport pipe can be effectively prevented at low cost. Moreover, since the molten Mg in the melt transport pipe that should be discharged can be sent into the reduction reaction vessel and used for the production of sponge titanium, the utilization efficiency of the molten Mg can be increased.

  Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A, 1B and 1C are schematic views showing an embodiment of the method for producing sponge titanium according to the present invention in the order of steps.

  In the sponge titanium manufacturing method of the present embodiment, first, as shown in FIG. 3B, the Mg container 40 is connected to the reduction reaction container 10 through the connection pipe 30. At this time, the inside of the reduction reaction vessel 10 is replaced with Ar gas. When the connection between the Mg container 40 and the reduction reaction container 10 is completed, Ar gas is injected into the container from the inert gas supply pipe 41 of the Mg container 40. Thereby, molten Mg 50 in the Mg container 40 is injected into the reduction reaction container 10 through the Mg discharge pipe 42, the connection pipe 30 and the melt transport pipe 13. This is the initial charge.

When the initial charge is finished, the connection pipe 30 and the Mg container 40 are separated from the reduction reaction vessel 10, the upper end of the melt transport pipe 13 is closed, and the liquid tetrachloride is supplied from the titanium tetrachloride supply pipe 11 of the reduction reaction vessel 10. Titanium chloride is dropped into the container. Thereby, sponge titanium 60 is generated in the reduction reaction vessel 10. At the same time, liquid MgCl ₂ 70 is by-produced and accumulates in the bottom of the reduction reaction vessel 10 (see FIGS. 3A and 1A).

  When the operation has elapsed for a certain period and the tap timing has come, the recovery container 20 is connected to the reduction reaction container 10 as shown in FIG. Specifically, the melt transport pipe 13 of the reduction reaction container 10 and the introduction pipe 21 of the recovery container 20 are connected by a connection pipe 30. At this time, the inside of the melt transport pipe 13 is filled with molten Mg to the same level as the inside of the reduction reaction vessel 10. Unlike the collection container 20 shown in FIG. 3A, the collection container 20 has an inert gas supply pipe 22 connected to the upper part of the container.

When the connection between the reduction reaction container 10 and the recovery container 20 is finished, Ar gas is injected from the inert gas supply pipe 22 of the recovery container 20 as shown in FIG. The pressurized gas reaches the melt transport pipe 13 through the introduction pipe 21 and the connection pipe 30 of the recovery container 20 and pushes down the liquid level of the molten Mg 50 in the melt transport pipe 13 downward. As a result, molten Mg 50 in the melt transport pipe 13 flows into the reduction reaction vessel 10. When the pressurization is continued, the liquid level of molten Mg 50 in the melt transport pipe 13 is lowered to the lower end opening of the melt transport pipe 13. As a result, molten Mg 50 is removed from the melt transport pipe 13 and injected into the melt in the reduction reaction vessel 10. Molten Mg50 injected into the melt in the reduction reaction vessel 10 floats above MgCl ₂ due to the difference in specific gravity.

  At the same time, the pressurized gas is injected into the melt in the reduction reaction vessel 10 as bubbles, and the pressure in the reduction reaction vessel 10 is rapidly increased. That is, while the molten Mg 50 in the melt transport pipe 13 is pushed into the reduction reaction container 10, the volume of the melt transport pipe 13 may be small, and the pressure in the reduction reaction container 10 is slightly increased. When the pressurized gas begins to be injected into the melt in the reduction reaction vessel 10, the pressure in the reduction reaction vessel 10 rapidly increases. The pressure in the reduction reaction vessel 10 is monitored by a pressure gauge (not shown), and the injection of the pressurized gas is stopped when a sudden pressure increase due to the intrusion of the pressurized gas is detected.

When the melt containing molten Mg 50 is removed from the melt transport pipe 13 in this way, as shown in FIG. 1 (c), Ar gas enters the container from the inert gas supply pipe 12 of the reduction reaction container 10. Press fit. As a result, the by-product MgCl ₂ accumulated in the bottom of the reduction reaction vessel 10 is discharged into the recovery vessel 20 through the melt transport pipe 13, the connection pipe 30 and the introduction pipe 21. At this time, the molten Mg 50 does not pass through the melt transport pipe 13, the connection pipe 30, which is also a melt transport pipe, and the introduction pipe 21. For this reason, blockage of the melt transport pipe including the connection pipe 30 is prevented.

When the tapping operation is performed smoothly and safely in this way, the connecting pipe 30 and the recovery container 20 are separated from the reduction reaction vessel 10 to prepare for the next tapping operation. During the tap operation for extracting MgCl ₂ from the reduction reaction vessel 10, a part of the molten Mg may be suspended and mixed in the discharged MgCl _2, and the molten Mg 50 may enter the melt transport pipe 13. When molten Mg 50 enters the melt transport pipe 13, it floats above MgCl ₂ due to the difference in specific gravity and collects near the liquid surface. For this reason, also when performing the next tap operation, the melt is pushed into the reduction reaction vessel 10 from the melt transport pipe 13 in advance, and then the tap operation is started.

  When performing the additional charge, similarly to the initial charge described above, the Mg container 40 is connected to the reduction reaction container 10, and Ar gas is injected into the container from the inert gas supply pipe 41 of the Mg container 40. Thereby, molten Mg 50 in the Mg container 40 is injected into the reduction reaction container 10 through the Mg discharge pipe 42, the connection pipe 30 and the melt transport pipe 13. After the additional charge is performed, the melt transport pipe 13 is filled with molten Mg50. Therefore, in the tap operation after the additional charge, the melt in the melt transport pipe 13 is the same as the tap operation after the initial charge. It is important to push the product into the reduction reaction vessel 10 in advance.

  In the above embodiment, from the relationship of performing the additional charge, the Mg container 40 was used for the initial charge, and the molten Mg 50 was injected from the melt transport pipe 13 into the reduction reaction container 10, but when the additional charge is not performed, In general, the upper charge of the reduction reaction vessel 10 is opened and the initial charge is performed from above. Even when additional charge is performed, the initial charge can be performed from above.

  In the above embodiment, the pressing of the melt in the melt transport pipe 13 during the tapping operation is performed by pressurizing the inside of the recovery container 20 connected to the melt transport pipe 13 with Ar gas. It is also possible to press-fit a pushing gas from a connecting pipe 30 that connects the reaction vessel 10 and the collection vessel 20. FIG. 2 shows the configuration of the main part of the connecting pipe 30 provided with a pushing-in gas injection mechanism.

  FIG. 2 shows the end of the connecting tube 30 that connects the reduction reaction vessel 10 and the recovery vessel 20 on the reaction vessel side. This connecting pipe 30 includes a vertical vertical pipe part 31 that is flange-coupled to the upper end part of the melt transport pipe 13, and an oblique pipe part that extends obliquely downward from the middle part of the vertical pipe part 31 toward the recovery container 20. 32 and an opening / closing mechanism 33 that moves up and down in the vertical pipe portion 31. A throttle part 34 that is opened and closed by the opening and closing mechanism 33 is provided in the lower part of the vertical pipe part 31, more specifically below the connection part with the oblique pipe part 32. The opening / closing mechanism 33 includes an inverted cone-shaped head portion 35 and an inert gas supply pipe 36 that also serves as an ascending / descending drive portion. The head portion 36 is attached to the lower end portion of the inert gas supply pipe 36 in a communicating state, and has an inert gas jet port 37 at the distal end portion (lower end portion), and is lowered in the vertical pipe portion 31. Then, the throttle portion 34 is closed, and is stored above the connecting portion with the inclined tube portion 32 in the raised state.

When the melt in the melt transport pipe 13 is pushed down, the head portion 36 descends to close the throttle portion 34, and in this state, Ar gas is ejected from the inert gas outlet 37 at the tip (lower end). . Thereby, the liquid level of the melt in the melt transport pipe 13 is lowered. At the time of tapping for discharging MgCl ₂ in the reduction reaction vessel 10, the head portion 36 rises to a retracted position above the connecting portion with the inclined tube portion 32 so as not to hinder the discharge of MgCl ₂ .

  It is possible to push in the melt in the melt transport pipe 13 during the tapping operation also by the connecting pipe 30 provided with such a pushing-in mechanism for the pushing gas.

  When producing about 10 tons of sponge titanium using the reduction reaction vessel 10, the melt in the melt transport pipe 13 was pushed down before tapping by the method of FIG. The number of taps performed within the reaction period was 11 times, and the total tap amount was 33.5 tons. Charging was performed 6 times including the initial charge. The initial charge amount is 6 tons, and the additional charge amount is 2.1 tons on average.

  When the melt in the melt transport pipe 13 before tapping was not pushed down, the clogging frequency of the melt transport pipe at the time of tapping was about 3 times per batch (in 11 taps) on an average of 10 batches. However, when the melt in the melt transport pipe 13 before tapping was pushed down, this became zero.

  When the melt in the melt transport pipe 13 before tapping is pushed down, the molten Mg remaining in the melt transport pipe 13 is returned into the reduction reaction container 10 without being discharged into the recovery container 20. There is no waste of molten Mg. The amount is estimated to be about 100 kg in this embodiment.

(A) (b) (c) is a schematic diagram which shows one Embodiment of the sponge titanium manufacturing method of this invention in order of a process. It is a block diagram of the main part of the connection pipe provided with the press-fitting mechanism for the pushing gas, and shows the end of the connection pipe on the reduction reaction vessel side. (A) (b) is a schematic diagram which shows the conventional sponge titanium manufacturing method in order of a process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reduction reaction container 11 Titanium tetrachloride supply pipe 12 Inert gas supply pipe 13 Melt transport pipe 20 Recovery container 21 Introduction pipe (melt transport pipe)
22 Inert gas supply pipe 30 Connection pipe (melt transport pipe)
31 Vertical pipe section 32 Slanted pipe section 33 Opening / closing mechanism 34 Throttle section 35 Head section 36 Inert gas supply pipe 40 Mg container 41 Inert gas supply pipe 50 Molten Mg
60 Sponge titanium 70 Byproduct MgCl ₂

Claims (3)

Sponge titanium is produced by holding molten Mg inside the reduction reaction vessel and reacting the molten Mg and TiCl ₄ in the furnace, and the molten MgCl ₂ as a by-product is formed vertically from the furnace bottom of the reduction reaction vessel during the reaction. In the method for producing sponge titanium, which is drawn out of the reduction reaction vessel through a tubular melt transport pipe,
Before extracting the molten MgCl ₂ in the reduction reaction vessel to the outside of the reduction reaction vessel through the melt transfer tube, a gas is injected into the melt transfer tube and the melt liquid level in the melt transfer tube is set to the melt transfer tube. A process for producing a titanium sponge, characterized in that the molten MgCl ₂ is extracted after being lowered to the opening on the container bottom side. 2. The titanium sponge production method according to claim 1, wherein molten Mg is charged into the reduction reaction vessel via the melt transport pipe, and after the charge, the melt liquid level in the melt transport pipe is set to the melt transport pipe. container bottom side down to the opening, titanium sponge manufacturing method of performing extraction of molten MgCl ₂ in. 3. The method of manufacturing titanium sponge according to claim 2, wherein the charging of the molten Mg, and the subsequent pressing of the molten material in the molten material transport pipe and the extraction of the molten MgCl ₂ are repeated a plurality of times.

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