JP2007302522A - Method of refining titanium tetrachloride and refiner used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of refining titanium tetrachloride, which effectively avoids precipitation of high-boiling components in a fractionating column and enables easy maintenance, and a refiner used for the same. <P>SOLUTION: In the method of refining titanium tetrachloride using the fractionating column, crude titanium tetrachloride is distilled by a distillation still, the obtained distillate rich in titanium tetrachloride is fed to and distilled in a simplified fractionating column connected downstream of the distillation still, and the distillate rich in titanium tetrachloride obtained in the simplified fractionating column is fed to and further distilled in a main fractionating column connected downstream of the simplified fractionating column. The titanium tetrachloride refiner is equipped with the distillation still for distilling the crude titanium tetrachloride, the simplified fractionating column connected downstream of the distillation still and the main fractionating column connected downstream of the simplified fractionating column. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for purifying crude titanium tetrachloride produced in a chlorination furnace and a technique for efficiently using a purification apparatus used therefor.

Titanium tetrachloride (TiCl ₄ ) is widely used as a raw material for titanium sponge and titanium oxide, which are raw materials for metallic titanium that are frequently used in various fields. Titanium tetrachloride is produced by supplying chlorine gas to a fluidized bed maintained at a high temperature composed of titanium ore and coke formed in a chlorination furnace and chlorinating.

  Since titanium tetrachloride produced in the chlorination furnace is in a gaseous state due to high temperature, it is cooled to below the boiling point of titanium tetrachloride and separated and recovered in a liquid state. The separated and recovered crude titanium tetrachloride can be purified in a distillation step to obtain highly purified titanium tetrachloride.

  The crude titanium tetrachloride separated and recovered in the liquid state contains a large number of chlorides such as silicon, niobium, aluminum and vanadium. For this reason, the crude titanium tetrachloride is subsequently purified by distillation to increase the purity, and purified titanium tetrachloride is produced.

  Distillation and purification equipment used for distillation of crude titanium tetrachloride has been using a general-purpose rectification column. However, in the production of high-purity titanium tetrachloride, which has been in the spotlight in recent years, the required characteristics of conventional equipment In some cases, it was difficult to satisfy the requirements.

  Further, as the purification efficiency of titanium tetrachloride is increased, the amount of impurities such as high boiling point components separated and removed from titanium tetrachloride also increases. Most of these impurities are separated and removed as effluent from the rectification column, but some of them adhere to and accumulate inside the rectification column, which may prevent or block the flow of gas and distillate inside the rectification column. There was a case where it was necessary to improve.

  On the other hand, in the known titanium tetrachloride production method, two rectifying columns having the same performance are used, and crude titanium tetrachloride is caused to flow in series in these rectifying columns. High-purity titanium tetrachloride is produced by defining the position of the distillate extracted from the second rectification column based on the extraction position (see, for example, Patent Document 1).

  Moreover, about the subject that a high boiling point component precipitates in the specific site | part in the distillation apparatus of titanium tetrachloride, and reduces the function of the said apparatus, by supplying refined titanium tetrachloride to the said high boiling point component precipitation site | part A technique for dissolving and extinguishing a high-boiling component is also disclosed (for example, see Patent Document 2).

  However, in Patent Document 1, since two rectifying columns having approximate performance are used, when the rectifying column is clogged, the rectifying column is approximately compared with the case where the rectifying column is operated alone. There was a problem that twice the recovery time was required. In addition, when the rectification column itself is clogged and maintained, the rectification column overhaul is handled. Such an overhaul of the rectification tower requires a relatively long time, and the purification process of titanium tetrachloride must be stopped during maintenance. Moreover, in patent document 2, since the titanium tetrachloride refine | purified once was returned to a distillation apparatus again and mixed with crude titanium tetrachloride, there existed a problem that the refinement | purification efficiency of titanium tetrachloride deteriorated.

  Thus, while maintaining the quality and purification efficiency of titanium tetrachloride, it is easy to maintain the distillation apparatus, and the distillation purification method of titanium tetrachloride does not stop the distillation process when maintaining the rectification apparatus and Equipment is required.

JP 2002-187718 A JP 2002-055540 A

  In a method for purifying titanium tetrachloride using a rectifying column, a method for purifying titanium tetrachloride that can effectively avoid precipitation of high-boiling components in the rectifying column and can be easily maintained, and The purpose is to provide a purification apparatus to be used.

  In view of this situation, we have intensively studied to solve the above problems, and when purifying titanium tetrachloride using a rectification column, a simple rectification column is placed in front of this rectification column. It has been found that the ability of the rectifying column can be dramatically improved by disposing a distillation kettle in front of the rectifying column, and the present invention has been completed.

  That is, the method for purifying titanium tetrachloride according to the present invention is a simple rectifying column in which crude titanium tetrachloride is distilled by a distillation kettle, and the obtained distillate rich in titanium tetrachloride is connected to the downstream side of the distillation kettle. The distillate rich in titanium tetrachloride obtained by the simple rectification column is supplied to the rectification column connected to the downstream side of the simple rectification column and further distilled. It is said.

  According to the present invention having the above configuration, the bottoms containing a large amount of high-boiling components as impurities are mostly trapped in the distillation kettle and further trapped in the simple rectification column in the next stage. Since the crude titanium tetrachloride having a relatively high purity is distilled, the purification capacity of the rectifying column can be improved.

  In the titanium tetrachloride purification method of the present invention, the bottoms rich in high-boiling components accumulated in the rectification column are returned to the simple rectification column, and the reflux liquid rich in high-boiling components at the bottom of the simple rectification column Returning to the still is a preferred embodiment. According to such an embodiment, it is possible to effectively avoid precipitation and deposition of high boiling point components in the rectification column while maintaining the purification capacity of the rectification column, and to return the can The titanium tetrachloride component contained in the liquid can be recovered by distillation again, which is preferable.

  In the method for purifying titanium tetrachloride according to the present invention, the interior of the rectifying column and the simple rectifying column is partitioned into a distillation chamber having a theoretical plate number communicating in series, and the simplified rectifying column is compared with the rectifying column. A preferred embodiment is to configure the rectifying column and the simple rectifying column so that the number of theoretical plates is small. According to such an embodiment, the simple rectification column has a smaller number of sections compared to the main rectification column, that is, the structure is simple and can be configured to an appropriate size. Even if there is, maintenance can be completed in a short time. As a result, there is also a realistic effect that a simple rectification tower can be prepared without stopping the purification process of titanium tetrachloride.

  Further, as described above, the apparatus for purifying titanium tetrachloride according to the present invention includes a distillation kettle for distilling crude titanium tetrachloride, a simple rectifying column connected to the downstream side of the distillation kettle, and the simple rectifying tower. The rectification column is connected to the downstream side of the rectification column, and the interior of the rectification column and the simple rectification column is partitioned into a distillation chamber having a theoretical plate number communicating in series. A preferred embodiment is that the number of theoretical plates of the simple rectification column is smaller than that of the rectification column.

  By using the above-described purification method and purification apparatus of the present invention, it is possible to effectively suppress precipitation and accumulation of impurities such as high-boiling components contained in the crude titanium tetrachloride in the rectification tower, while maintaining high purity. The effect is that titanium tetrachloride can be produced efficiently.

The best embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows steps relating to a titanium tetrachloride purification apparatus of the present invention and a titanium tetrachloride purification method using the same. Reference numeral 1 is a distillation kettle in which crude titanium tetrachloride is first supplied for distillation. Since the crude titanium tetrachloride from the previous manufacturing process is supplied to the distillation kettle 1, the crude titanium tetrachloride contains coke and ore powder (hereinafter simply referred to as “solid impurities”) that are residues during the reaction. And impurities such as high-boiling components and low-boiling components are dissolved. Therefore, precipitation and clogging of the impurities are likely to occur inside the distillation apparatus. Therefore, it is preferable to select the structure of the still 1 that is easy to maintain.

  A simple rectification column 2 for supplying a distillate from the distillation kettle 1 is connected downstream of the distillation kettle 1. The crude titanium tetrachloride from which most of the solid impurities have been removed by the distillation kettle 1 and whose purity has been raised to some extent is further distilled in the simple rectification column 2. The rectifying column 3 is connected downstream of the simple rectifying column 2, and the crude titanium tetrachloride distillate whose purity has been greatly increased by the simple rectifying column 2 is further distilled in the rectifying column 3. As a result, the final product, purified titanium tetrachloride, is obtained.

  By arranging the simple rectification column between the distillation kettle and the rectification column in this way, the absolute amount of high-boiling components brought into the rectification column is suppressed, and it is mixed in the titanium tetrachloride. Incorporation of the solid impurities into the rectification column can be effectively avoided. As a result, it is possible to effectively avoid clogging of the flow path of the gas or the distillate in the rectification column, which often occurs due to the accumulation of the high-boiling components and the accumulation of solid matter. As a result, there is an effect that maintenance work of the rectification tower can be largely avoided. In addition, a reduction in operating rate of the titanium tetrachloride production apparatus according to the present invention can be effectively avoided.

  FIG. 2 shows a schematic diagram of another embodiment of the present invention. The difference from the embodiment in FIG. 1 is that the bottoms of the rectification tower 3 are returned to the simple rectification tower 2 (reference numeral 4: return liquid 1), and the reflux liquid of the simple rectification tower 2 is returned to the distillation tank 1. (Reference 5: return liquid 2). In this way, by extracting the bottoms from each stage, the amount of impurities in the rectifying column at each stage can be reduced, so that clogging due to precipitation of impurities and high-efficiency distillation can be performed. . The bottoms also contain titanium tetrachloride, which is the target component. However, since this can be returned to the previous stage and distilled again, the recovery rate of titanium tetrachloride can be improved.

  In the titanium tetrachloride purification apparatus according to the present invention, the interior of the rectifying column and the simplified rectifying column is partitioned into a distillation chamber having a theoretical plate number communicating in series. It is preferable to configure the tower so that the number of theoretical plates is small. In this case, the smaller number of theoretical plates means that the apparatus is smaller than the rectifying column and the apparatus structure is simple, such as a smaller number of sections. By adopting such an apparatus configuration, there is an effect that a simple rectification column blocked by accumulation of high-boiling components and solid impurities can be easily maintained.

  The simple rectification tower can be constituted by, for example, a bubble bell tower as shown in FIG. The number of physical stages is about 3 to 5, and the object of the present invention can be achieved. In addition, the simple rectification column according to the present invention is not limited to the bubble bell tower, and may be configured with a simple shelf. In any case, the structure is not particularly limited as long as it has a function of separating and removing high-boiling components and solid impurities contained in titanium tetrachloride and the maintenance work is simple.

  In addition, as shown in FIG. 4, two simple rectifying columns 2 can be arranged in parallel. With this arrangement, when one of the simple rectification towers 2 is blocked, maintenance work can be performed without stopping the operation of the entire titanium tetrachloride rectification process by switching to another simple rectification tower. Can continue.

  Titanium tetrachloride from which high-boiling components have been separated and removed by the simple rectification column 2 arranged in the preceding stage is supplied to the rectification column 3 arranged downstream of the simple rectification column 2. Therefore, the titanium tetrachloride has a structure having a low number of low-boiling components compared to the high-boiling components and a structure having a theoretical plate number that can separate and remove these low-boiling components in addition to the high-boiling components. preferable.

  The low-boiling components described above are arsenic and tin chlorides, and since the boiling points of these chlorides are close to the boiling points of titanium tetrachloride, it is preferable to use a rectifying column with high separation performance. In this sense, the number of theoretical plates is preferably at least 10 or more, and more preferably 20 or more. However, even if the number of theoretical plates is increased to some extent, it does not increase in proportion to the separation performance. Therefore, it is considered that the practical upper limit is about 40 plates.

  Next, preferred embodiments of the operation methods of the distillation tank, the simple rectification column, and the main rectification column will be described in detail.

1) Distilling kettle In the distilling kettle, high-boiling components dissolved in titanium tetrachloride such as iron and aluminum chlorides are separated, and ore and coke fines carried over from the chlorination furnace are separated. It is preferable to drive. Therefore, by operating so that the residence time of titanium tetrachloride is sufficient, it becomes possible to efficiently separate the solid matter.

  Since the vapor pressure of the high boiling point component dissolved in the titanium tetrachloride is proportional to the temperature of the distillation kettle, the lower the operating temperature of the distillation kettle 1 is preferable for separating and removing the high boiling point component. On the other hand, it is preferable that the temperature of the still 1 is higher in view of the distillation ability of titanium tetrachloride.

  Further, it is preferable that a part of the bottoms from the simple rectification column 2 disposed downstream of the distillation kettle 1 is returned to the distillation kettle 1. The titanium tetrachloride in the bottoms returned to the distillation kettle 1 is evaporated again and transferred to the simple rectification column 2. For this reason, since the concentration of the high-boiling component in the still 1 always tends to increase, it is preferable to periodically extract a predetermined amount of liquid from the bottom of the still 1.

2) Simple rectification tower The simple rectification tower 2 is preferably arranged at the front stage of the main rectification tower 3 and at the rear stage of the distillation still 1. By arrange | positioning in this way, the said simple rectification tower 2 can isolate | separate and remove the high boiling point component and solid impurity in the titanium tetrachloride to supply beforehand.

  The ratio of the return flow rate of the reflux liquid from the simple rectification column 2 to the distillation column 1 to the flow rate of titanium tetrachloride supplied from the distillation column 1 to the simple rectification column 2 is in the range of 0.1 to 0.3. It is preferable to maintain. By maintaining such a ratio, the required production amount of titanium tetrachloride can be maintained while appropriately maintaining the concentration of the high boiling point component in the simple rectification column 2.

  When the simple rectifying column 2 is constituted by a bubble bell tower as shown in FIG. 3, the bottom of the bubble bell tower in the flow rate of titanium tetrachloride discharged from the top of the bubble bell tower to the rectifying column 3 is provided. The returning flow rate ratio (reflux ratio) is preferably maintained in the range of 0.1 to 0.5. By maintaining such a reflux ratio, it is possible to maintain the concentration of the high boiling point component in the titanium tetrachloride within the target range while securing the production amount of the titanium tetrachloride.

  It is preferable that the high-boiling substances accumulated at the bottom of the simple rectification column 2 are appropriately extracted and returned to the distillation kettle 1. By extracting such high-boiling substances, the concentration of high-boiling substances in the simple rectification column 2 can be reduced. As a result, the high boiling point separation performance in the simple rectification column 2 can be maintained at a high level.

3) Main rectification column The main rectification column 3 is supplied with titanium tetrachloride having a large amount of low-boiling components from which high-boiling components are substantially separated. Therefore, by raising the temperature of the reboiler (not shown) at the bottom of the rectifying column 3 higher than the temperature of the reboiler of the simple rectifying column 2, low boiling point components can be efficiently concentrated at the top of the column.

  However, in accordance with this, the amount of evaporation of titanium tetrachloride also increases and accumulates at the top of the head, and the concentration of low boiling point components in titanium tetrachloride may not decrease. Therefore, it is preferable to set the reboiler temperature within an appropriate range in consideration of the impurity concentration and production amount in titanium tetrachloride. In this invention, it is preferable to maintain in the range of 130 to 145 degreeC.

  As described above, the rectifying column 3 is preferably configured to separate and remove the low boiling point component in titanium tetrachloride and the low boiling point component close to the boiling point of titanium tetrachloride. Therefore, as described above, the number of theoretical plates is preferably at least 10 or more, and more preferably 20 or more. However, since the degree of improvement in rectification efficiency tends to be saturated even if the number of stages is excessively increased, it is preferable that about 40 stages be a practical upper limit.

  Next, a part of the liquid titanium tetrachloride condensed at the top of the rectifying column 3 is appropriately extracted from the top of the tower, whereby the low boiling point components in the titanium tetrachloride can be effectively separated.

  In the present invention, as described above, a part of the bottoms of the rectifying column 3 is returned to the bottom of the simple rectifying column 2, and the bottoms of the simple rectifying column 2 is returned to the distillation still 1. It is preferable to operate as follows. By forming such a bottoms flow, the flow of the titanium tetrachloride gas evaporated from the reboiler and the bottoms are transferred between the distillation kettle 1, the simple fractionator 2, and the main fractionator 3. As a result, the rectification efficiency of the entire rectification process shown in FIG. 1 can be further increased.

  The titanium tetrachloride purified by the simple rectifying column 2 is preferably introduced into the column from the middle part of the rectifying column 3. By introducing titanium tetrachloride having a large amount of low-boiling components from such a position, the low-boiling components can be concentrated at the top of the rectifying column 3. Therefore, the extraction position of the product titanium tetrachloride from the rectifying column 3 is to be extracted from a position close to the bottom of the rectifying column 3 with few low-boiling components because most of the high-boiling components are separated and removed. However, it tends to increase the concentration of the high boiling point component as it approaches the bottom. Therefore, it is preferable to determine the overall extraction position from the required quality of titanium tetrachloride. Therefore, it is preferable to provide a plurality of positions where the product titanium tetrachloride is extracted from the rectifying column 3 in the vertical direction so that the position where the product titanium tetrachloride is extracted can be appropriately changed by switching valves.

  As yet another preferred embodiment, the simple rectification column 2 described above can be directly engaged with the top of the distillation still 1. With such an arrangement, the rectification apparatus can be configured in a compact manner, which can be configured with only a distillation still and a main rectification column.

  If a distillation column having performance comparable to that of the rectifying column is not disposed in the previous stage of the rectifying column, there is a concern that the quality of the purified titanium tetrachloride may be deteriorated. In addition, by adding an operation to return the bottoms of the rectification column to the simple rectification column and to return the bottoms of the rectification column to the distillation kettle, the entire rectification process can be countercurrently contacted with the gas and the distillate. As a result, despite the fact that a simple rectification column is used, a tetrachloride with excellent quality equivalent to a purification device in which a distillation column with a performance comparable to that of this rectification column is arranged in the previous stage of this rectification column. It is thought that titanium is refined. That is, it is possible to solve the problem of clogging due to impurities generated when the rectifying columns having the same performance are connected in series, and to maintain high quality.

  By using the method and apparatus configuration as described above, high-purity titanium tetrachloride can be efficiently produced. In addition, by arranging a simple rectification column in front of the rectification column, there is an effect that the high-boiling components in titanium tetrachloride brought into the rectification column can be efficiently separated and removed. In addition, the simple rectification tower has a simple structure and is smaller than the rectification tower. Therefore, the time and man-hours required for maintenance are significantly reduced compared to the case where the rectification tower is installed. This is an effect not found in the prior art.

[Example 1]
The apparatus and operating conditions used in this example as shown in FIG. 2 are shown below.
1. Apparatus 1) Distillation kettle ・ Capacity: 20,000 kg
2) Simple rectification tower ・ Type: bubble bell tower ・ Number of physical stages: 10 stages 3) Main rectification tower ・ Type: packed tower ・ Number of physical stages: 40 stages
2. Operation method 1) Distillation kettle ・ Temperature: 130 ° C to 145 ° C
・ Return flow rate ratio from simple rectification column to evaporation amount: 0.3
2) Simple rectification column ・ Temperature: 130 ° C to 140 ° C
Reflux ratio (return flow ratio from the rectification column to the evaporation amount): 0.3
3) This rectification tower ・ Temperature: 130 ° C to 145 ° C
Reflux ratio (ratio of the flow rate flowing from the top to the bottom of the rectification column to the flow rate supplied from the simple rectification column to the rectification column): 2.0

  A total of 6,000 t / month of titanium tetrachloride was distilled and purified using the apparatus shown in FIG. As a result, it was confirmed that high-purity titanium tetrachloride as shown in Table 1 was produced.

  Since the pressure loss before and after the simple rectifying column increased and approached the upper limit after 12 months of operation at the above production rate, the operation was continued after switching to the preliminary simple rectifying column 2 as shown in FIG. Continued. On the other hand, the simple rectification tower with increased pressure loss was returned to its original position after dismantling.

[Comparative Example 1]
The conditions of Example 1 were the same except that the simple rectification column 2 was not used, and titanium tetrachloride was distilled and purified. As a result, since the pressure loss of the rectifying column approached the reference value in the 84th month from the start of operation, the distillation operation of titanium tetrachloride was stopped and the rectifying column 3 was prepared.

  In addition, when the man-hour required for the maintenance of the simple rectification tower of Example 1 is 1, the man-hour required for the maintenance of the rectification tower of Comparative Example 1 has reached 50 times. However, since the maintenance interval of the simple rectification tower is shorter than that of the main rectification tower, even if this is corrected, the man-hour required for the maintenance of the main rectification tower is about seven times that of the first embodiment. Therefore, a remarkable effect was confirmed in which a simple rectification column was placed in front of the rectification column.

  From the above Examples and Comparative Examples, it was confirmed that the blockage time of the rectification column can be extended by arranging the simple rectification column in the previous stage of the rectification column. In addition, by returning the effluent from this rectification column to the simple rectification column in the previous stage, and returning the effluent from the simple rectification column to the distillation kettle, the production efficiency of titanium tetrachloride is enhanced while increasing the purification effect. It was also confirmed that the amount could be secured.

  Since the simple rectification tower has a simple structure and an appropriate size, the number of steps required for maintenance can be greatly reduced as compared with the rectification tower. In addition, by arranging a plurality of simple rectifying columns in parallel, the operation of the distillation process can be continued even during maintenance of the simple rectifying column.

  By employing the titanium tetrachloride purification method and purification apparatus of the present invention, high-purity titanium tetrachloride suitable for producing high-purity titanium can be efficiently obtained. This contributes to the cost reduction of high purity titanium production.

It is a schematic diagram which shows one Embodiment of the purification method and refinement | purification apparatus of titanium tetrachloride of this invention. It is a schematic diagram which shows other embodiment of the purification method and purification apparatus of titanium tetrachloride of this invention. It is a schematic diagram which shows one Embodiment of the simple rectification column of this invention. It is a schematic diagram which shows the example of the parallel connection of the simple rectification tower of this invention.

Explanation of symbols

1 Distiller 2 Simple rectification column 3 Main rectification column 4 Return liquid 1
5 Return liquid 2

Claims (7)

  A method for purifying titanium tetrachloride using a rectifying column, comprising distilling crude titanium tetrachloride with a distillation kettle, and diluting the resulting titanium tetrachloride-rich distillate to a downstream side of the distillation kettle. The distillate rich in titanium tetrachloride obtained in the simple rectification column is supplied to the rectification column connected to the downstream side of the simple rectification column for further distillation. A method for purifying titanium tetrachloride, comprising:   The bottoms rich in high boiling components accumulated in the rectifying column are returned to the simple rectifying column, and the reflux liquid rich in high boiling components at the bottom of the simple rectifying column is returned to the distillation kettle. The method for purifying titanium tetrachloride according to claim 1.   The inside of the rectifying column and the simple rectifying column is partitioned into a distillation chamber having a theoretical plate number communicating in series, and the theoretical rectifying column has a smaller theoretical plate number than the main rectifying column. The method for purifying titanium tetrachloride according to claim 1 or 2, wherein the rectifying column and the simple rectifying column are constituted.   The method for purifying titanium tetrachloride according to any one of claims 1 to 3, wherein a plurality of the simple rectifying columns are used and arranged in parallel.   A distillation kettle for distilling crude titanium tetrachloride, a simple rectifying column connected to the downstream side of the distillation kettle, and a main rectifying column connected to the downstream side of the simple rectifying column Titanium tetrachloride purification equipment.   The inside of the rectifying column and the simplified rectifying column is partitioned into a distillation chamber having a theoretical plate number communicating in series, and the theoretical rectifying column has a smaller theoretical plate number than the main rectifying column. The apparatus for purifying titanium tetrachloride according to claim 5.   The apparatus for purifying titanium tetrachloride according to claim 5 or 6, wherein the simple rectifying column is disposed to be engaged with a top portion of the distillation kettle.

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