JPH0643245B2 - Method for producing silicon hexachloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention provides a raw material for disilane, which has recently attracted particular attention as a special gas for producing raw materials such as silicon-based semiconductors and amorphous silicon. The present invention relates to a very useful method for producing silicon hexachloride.

[Prior Art] Silicon hexachloride is thermally decomposed in, for example, a hydrogen stream to produce polycrystalline silicon or single crystal silicon, or heat resistance,
For the production of chemical vapor deposition films or powders of SiC, Si ₃ N _{4 which} are excellent in wear resistance, corrosion resistance, etc., and for the synthesis of organic silicon compounds, it has the features not found in conventional silicon chlorides. It can be expected that the demand will greatly increase in the future.

The method for producing silicon hexachloride is usually carried out by reacting silicon alloy such as ferrosilicon, calcium silicon, magnesium silicon or silicon metal with chlorine at high temperature (US Pat. No. 2,602,728, No. 2).
621111).

In performing the above reaction, a fixed bed type reactor or a fluidized bed type reactor has been conventionally used, but since it is a solid gas reaction with extremely large heat generation, the reaction conditions suitable for the production of silicon hexachloride are controlled. It was difficult and unfinished to do on an industrial scale.

That is, if the reaction conditions cannot be controlled under suitable conditions, in addition to silicon hexachloride, silicon tetrachloride or higher-order silicon chlorides of silicon octachloride or higher are also formed, and the yield of silicon hexachloride is significantly reduced.

[Problems to be solved by the invention]

Conventionally, the reaction between silicon alloy or silicon metal (hereinafter referred to as silicon raw material) and chlorine has been performed by charging a fixed bed reactor with the silicon raw material and then reacting with chlorine at a high temperature. There were the following problems.

1) Since the reaction is exothermic, a temperature distribution occurs in the reactor during the reaction, and it is difficult to control the temperature uniformly.

2) The reaction residue solidifies due to volume expansion due to by-produced chlorides such as iron chloride and calcium chloride produced as a by-product during the reaction, and it is difficult to take out the reaction residue after the reaction.

3) The reaction rate of the silicon raw material is low.

Therefore, the fixed bed reactor has various problems in that it can be carried out on an industrial scale, such as the size of the reactor being limited.

Some of the above problems can be alleviated to some extent by using a fluidized bed reactor. For example, it becomes easy to maintain the temperature uniformity. However, even in the fluidized bed reactor, 1) a large amount of gas flow required for fluidization is required, and a large amount of equipment and utilities are required.

2) By-products such as finely powdered chlorides such as iron chloride and calcium chloride are entrained in a large amount of gas flow necessary for fluidization and flow out from the reactor together with silicon chlorides, so that separation of these is difficult. In addition, the fine particles cause clogging of the piping and the like.

3) The reaction rate of chlorine is low, and it requires a great deal of cost to remove unreacted substances or by-products.

However, it was not industrially suitable.

In view of the problems of the fixed bed type and fluidized bed type reactors as described above, the controllability of the reaction temperature that occurs during the large-scale production of silicon hexachloride, the problem caused by the handling of the residue, and the problem related to the clogging of the piping, etc. As a result of diligent research to solve the above problems, the present inventors first conducted a method for producing silicon hexachloride characterized by using a vibration reactor when producing silicon hexachloride by reacting a silicon raw material with chlorine. Invented and applied for a patent (Japanese Patent Application No. 6)
0-151297, Japanese Patent Application No. 61-41422). Furthermore, the inventors of the present invention have earnestly studied a method in which the reaction temperature can be controlled more easily, the yield of silicon hexachloride is high, the processing capacity is large, and the silicon hexachloride can be produced industrially stably. The invention was completed.

(B) Structure of the Invention [Means for Solving the Problems] The present invention uses a vibration reactor when reacting a silicon raw material selected from a silicon alloy and metallic silicon with chlorine to produce silicon hexachloride. The method for producing silicon hexachloride is characterized in that the silicon raw material is reacted while being transferred from the silicon raw material supply port of the reactor toward the outlet by vibrating the reactor.

[Action]

According to the method of the present invention, by vibrating the reactor using a vibration type reactor, vibration is transmitted to the silicon raw material in the reactor, the silicon raw materials move and mix, and the silicon raw material and chlorine in the vapor phase part are mixed. To increase the effective contact area and facilitate the reaction. Therefore, as in the case of a fixed bed reactor, there is no problem of solidification of reaction residues and adhesion to the vessel wall.
Further, unlike the case of the fluidized bed reactor, the problem caused by the large amount of gas required for fluidization does not occur.

Further, according to the present invention, the silicon raw material is reacted while being transferred from the silicon raw material supply port toward the outlet by the vibration of the reactor, whereby the control of the reaction temperature is significantly facilitated.

The heat of reaction is large in the reaction between the silicon raw material and chlorine,
It is necessary to effectively remove the heat of reaction to maintain the desired reaction temperature. In order to remove a large reaction heat in the reaction between the silicon raw material and chlorine, it is necessary to enhance the heat transfer efficiency of the silicon raw material layer, but if the stirring and movement of the silicon raw material layer are insufficient, temperature distribution easily occurs, The overall heat transfer coefficient becomes low, and it is difficult to expect a smooth reaction.

According to the present invention, the silicon raw material is vibrated so that the silicon raw material is fluidized and transferred from the silicon raw material supply port of the reactor in the direction of the outlet to transfer heat between the silicon raw materials or cool the silicon raw material and the outer jacket. The heat transfer between the heat medium and the vessel wall is good, and efficient heat removal can be performed. Further, in the method of the present invention, it is relatively easy to increase the heat transfer area between the reactor and the silicon raw material. Furthermore, it is possible to prevent local accumulation of reaction heat. On the other hand, according to the present invention,
In particular, when an unreacted silicon material circulation system as described below is adopted, it is possible to carry out the reaction by reducing the amount of silicon material present in the reactor, that is, by reducing the thickness of the silicon material layer. Therefore, the heat removal efficiency is higher and the temperature control is easier.

[Reaction material]

Examples of the silicon alloy, which is one of the silicon raw materials in the present invention, include calcium silicon, magnesium silicon, and ferrosilicon, and ferrosilicon is particularly preferable. The silicon content in the silicon alloy is preferably 30% by weight or more, though it depends on the kind. If it is less than 30% by weight, alloy elements other than silicon of the silicon alloy are chlorinated.
Chlorine intensity may be large.

The silicon raw materials may be used alone or as a mixture, and may contain other metals such as aluminum and manganese.

It is more preferable to use a silicon alloy because the reaction temperature is lower and silicon hexachloride can be obtained in a higher yield.

It is usually preferable to use a silicon raw material in the form of particles,
In the case of large particles, it is advisable to grind them to obtain an appropriate particle size before use. The particle size is preferably 5 mesh sieve passed product to 300 mesh sieve passed product, more preferably 20 mesh sieve passed product to
It is a 200 mesh sieve product. Coarse particles that exceed the size of 5 mesh screen may have low reactivity with chlorine.
For example, it may be accompanied by a reaction product gas, an inert gas supplied to the reaction system, or the like, and may cause a clogging of a pipe or the like.

The chlorine of the present invention is not particularly limited, but normally it is preferable to use well-dried chlorine gas, for example, a cylinder-filled product or a product passed through a desiccant may be used.

Chlorine may be used alone or diluted with a diluent gas. The diluent gas may be any gas as long as it does not react with silicon hexachloride, and examples thereof include N ₂ , He, Ar, and silicon tetrachloride.

The supply ratio of chlorine to the silicon raw material is not particularly limited, and the optimum ratio varies depending on the particle size of the silicon raw material, the vibration conditions of the vibration reactor, the transfer conditions, the reaction temperature, the partition plate, etc. Unit amount of silicon raw material (k
5-100 / hr is preferred per g). If it is less than 5 / hr, the reaction time is too long, and it cannot be said that it is preferable.
If it exceeds / hr, unreacted chlorine may increase.

When chlorine is supplied to the reaction system together with the diluting gas, there are advantages such as easy control of reaction heat, and the diluting ratio in that case is preferably in the range of 0.05 to 5 of diluting gas / chlorine gas, and usually 1 or less is sufficient. is there.

[Reactor]

The vibrating reactor used in the present invention comprises a reactor and an oscillating device for vibrating the reactor.

The reactor is not limited to any shape as long as it has an oscillating device and can transfer the silicon raw material from the silicon raw material supply port of the vibration type reactor to the outlet direction, and examples thereof include a vertical type and a horizontal type.

As an example, a horizontal reactor with a rectangular cross section,
A type in which the silicon raw material is transferred laterally, or a vertical reactor in which the silicon raw material transfer surface is attached in a spiral shape,
Examples include a type in which a silicon raw material is moved in a circle and consequently is transferred in the vertical direction.

The outer surface of the reactor is usually provided with a jacket for passing a heat medium for controlling the reaction temperature, and the reactor has a silicon raw material, chlorine, diluent gas supply port, generated gas, unreacted chlorine, diluent gas outlet, It has an outlet for the silicon raw material after the reaction, and the pipes of these supply port and outlet are connected to each pipe and equipment by a flexible tube and a coiled pipe in order to absorb vibration.

It is more desirable to provide a partition plate in the gas phase portion of the reactor. That is, by providing a partition plate in the gas phase portion of the reactor, diffusion of chlorine into the silicon raw material can be promoted, the reaction temperature can be easily controlled appropriately, and the reaction rate can be further improved.

The partition plate is provided in the reaction gas phase portion in the reactor, and its material is not particularly limited as long as it can withstand the reaction temperature without being attacked by chlorine, but usually stainless steel, heat resistant plastic, etc. Used.

The shape of the partition plate may be any shape as long as it can prevent the flow of the air flow in the gas phase part in the reactor and thereby promote the diffusion of chlorine into the silicon raw material, but the reaction in contact with the gas phase part The shape is in contact with the inner wall of the vessel and its shape is a cross section of the gas phase part (cross section when cut at right angles to the passage direction of the air flow
The same applies hereinafter), which can shield at least the upper part of the vapor phase part is suitable. It is necessary that the size of the partition plate does not prevent the transfer of the silicon raw material, but the reactor relative to the cross-sectional area of the gas phase part (cross-sectional area when cut at right angles to the flow direction of the air flow) It is desirable to be able to shield the space from the upper part to more than one-third or up to the extent of contact with the silicon raw material layer. Especially, in the two-thirds of the cross-sectional area of the gas phase portion or the starting state, the transfer of the silicon raw material cannot be prevented and the silicon raw material can be prevented. It is desirable to provide a partition plate large enough to allow a slight gap between the layers. If the shielding area is less than one-third, chlorine gas may pass through and be discharged without participating in the reaction.

It is usually desirable to install the partition plate immediately before the produced gas outlet so that the gas flow in the reaction gas phase part is obstructed and the stagnant part of the air flow is efficiently formed. Further, when a plurality of chlorine supply ports are provided in the reactor, it is possible to provide a partition plate for each supply port to divide the surfaces. In this case, it is possible to perform more detailed operation management such as changing the amount of chlorine supply or the temperature of the heat medium corresponding to each section. Of course, even when there are a plurality of chlorine supply ports, one partition plate may be provided immediately before the reaction product gas outlet. The partition plate can be attached to the reactor body by welding, screwing, or clamping with a flange. A thermometer may be attached to measure the temperature of each part in the reactor.

The oscillator may be any device that causes the reactor to vibrate. For example, as shown in page 844 of the Handbook of Chemical Equipment (edited by the Chemical Industry Association, published June 15, 1945), it is industrially unbalanced. A weight type oscillating device, an eccentric shaft, a crank type oscillating device, an electromagnetic oscillating device, or the like.

The oscillation condition of the oscillator in the reaction of the present invention is that the silicon raw material is sufficiently vibrated to be in a good flow state, the temperature distribution can be sufficiently controlled, the silicon raw material is transferred, and the appropriate equipment cost of the oscillator is provided. Considering the ease of selecting flexible tubes for connecting chlorine, product gas, and heat medium piping to the reactor, the vibration frequency is 300 to 3,600 cpm and the amplitude.
0.5 to 30 mm is preferable, more preferably 400
.About.1,8000 cpm and amplitude 1-10 mm.

Further, the vibration direction of the reactor may be horizontal, vertical, or straight, and may be straight, circular, oval, twisted,
Although any of the turning motions may be used, in order to transfer the silicon raw material by applying vibration, it is desirable that the vibration direction is oblique to the horizontal direction.

It is generally desirable that the vibration reactor is equipped with a vibration isolator for elastically supporting the support base. A steel coil spring, a leaf spring, an air spring, or the like is used as the vibration isolator.

〔transfer〕

In the present invention, the means for reacting with chlorine while transferring the silicon raw material from the supply port of the silicon raw material of the vibration type reactor to the chlorine utilizes the vibration of the vibration type reactor itself. As a method of transferring, considering that the reaction heat can be removed efficiently and the silicon raw material can be transferred sequentially in a certain direction on an industrial scale, the horizontal direction (direction in contact with the vertical direction at 90 °) is considered. On the other hand, it is desirable that the silicon raw material is oscillated obliquely upward in the transfer direction by the vibration of the silicon raw material being imparted to the silicon raw material, and the silicon raw material is transferred to the silicon raw material outlet direction. When the vibration direction given to the silicon raw material is the vertical direction, the silicon raw material vibrates mainly in the vertical direction, so that the transfer does not easily occur. On the other hand, when the horizontal vibration is applied, the silicon raw material reciprocates on the transfer surface. , It is difficult to achieve the purpose of transfer.

The preferred angle of the vibration direction is 20 ° to 85 °, and more preferably 30 ° to 80 ° with respect to the transfer surface of the silicon raw material in the reactor. If it is less than 20 °, the transfer rate is too high and the silicon raw material may be transferred until it sufficiently participates in the reaction. If it exceeds 85 °, an appropriate transfer rate cannot be obtained and transfer becomes non-uniform, resulting in temperature distribution. There is a risk.

As a device capable of transferring the silicon raw material as described above, a so-called vibrating conveyor, a vibrating elevator, a vibrating feeder, which is a device generally used for transporting powder, granules, lumps, etc., The reactor itself can be used as a vibration type reactor. A typical structure of the device is, for example, as shown in page 814 of Chemical Device Handbook (edited by Chemical Engineering Society, published June 15, 1945), a vibrated body on which a transport material is placed, that is, a trough (in the case of the present invention, The reactor corresponds to this), the spring, the drive and the base frame. As the drive unit, one that gives the trough a rotary motion of the motor as a sinusoidal linear motion by the crankshaft and rod, one that uses the attractive force of the electromagnet, and an unbalanced weight attached to both ends of the motor, the centrifugal force generated by its rotation. There is something that uses the (vibration motor), etc., and both are attached so that the linear vibration direction has an angle with the transfer surface in combination with the attachment angle of the spring.

The transfer rate of the silicon raw material is affected by the frequency, amplitude and vibration angle, but is preferably 0.1 to 20 m / mm, more preferably 0.5 to 15 m / mm. If it is less than 0.1 m / mm, the transfer of silicon raw material may become non-uniform and a temperature distribution may occur, and if it exceeds 20 m / mm, the reactivity with chlorine, the temperature uniformity, etc. are almost unchanged and the circulating amount of silicon raw material. There is a risk that the efficiency will be deteriorated only by increasing.

The retention amount of the silicon raw material in the reactor is preferably combined with the by-product so as to form a relatively thin layer of 200 kg / m ² or less per effective heat transfer area in the reactor.
5 kg / m ² is more preferable. When it exceeds 200 kg / m ² , it becomes difficult to control the temperature in the reactor to a predetermined temperature,
The overall heat transfer coefficient is also reduced, which adversely affects the reaction results. Further, when the silicon raw material is circulated and used as will be described later, the amount of circulation is increased, and there is a possibility that the energy required for circulation is wasted. On the contrary, if it is less than 2.5 kg / m ² , the flow of the silicon raw material in the reactor becomes non-uniform and the effective heat transfer area may not be utilized.

[Reaction method]

The reaction method of the present invention is specifically described as follows, for example. A sufficiently dried silicon raw material is fed to a reactor as shown in FIG. The amount of silicon raw material retained in the reactor is as described above, and in the case of the reactor as shown in FIG. 1, for example, it can be controlled by the supply amount of the rotary valve below the hopper. The vibration conditions by the oscillator and the transfer conditions at the time of transfer are as described above.

In the present invention, the silicon raw material is reacted with chlorine while being transferred, but the reaction amount when the silicon raw material is once passed through the reactor is not so large. Therefore, it is desirable to return all or part of the partially chlorinated silicon raw material coming out from the silicon raw material outlet to the silicon raw material supply port of the reactor and circulate it for use. As a means for circulating the silicon raw material, a means used for ordinary powder transportation means such as a conveyor type, a screw type, an air flow type, etc. may be used as long as it is a system that is shielded from the outside air. Further, in the form in which the silicon raw material is transferred vertically upward by making the reactor spiral, it can be returned by gravity.

At the silicon raw material supply port of the reactor, for the purpose of absorbing an increase in volume due to the fluctuation of the silicon raw material at the start of the reaction or when the silicon raw material is circulated and the influence of metal chloride produced by the reaction, For example, it is desirable to provide the hopper shown in FIG.

When the method of circulating the silicon raw material is adopted, all or part of the partially chlorinated silicon raw material coming out from the silicon raw material outlet of the reactor is extracted, and the by-produced metal chloride is separated off. It is more desirable to take the action of returning to the reaction system again. That is, when a silicon alloy is used as a silicon raw material, for example, when ferrosilicon is used, ferric chloride is used, and when calcium silicon is used, a metal chloride containing calcium chloride as a main component, and a metal silicon Even when using, the metal chlorides resulting from the impurities may accumulate in the reaction system and reduce the reactivity with chlorine. Therefore, separating the by-product metal chloride and circulating the silicon raw material enables the reaction to be carried out more efficiently.

As a method of separating the by-product metal chloride, a method of dissolving the metal chloride by washing with water and drying, a method of sieving by utilizing the difference in particle size between the silicon raw material and the metal chloride or a method of classifying by an air flow, and a method of heating the metal chloride Examples include a method of sublimating an object.

After supplying the silicon raw material to the reactor and setting vibration and transfer conditions, a heating medium is passed through the reactor jacket to raise the temperature to a predetermined temperature. At this time, it is desirable to flow a diluent gas such as nitrogen.

The reaction temperature varies depending on the type of silicon raw material, but is 100 to 5
00 ° C is preferred. If it is less than 100 ° C, the reaction rate of chlorine tends to be low, and if it exceeds 500 ° C, the yield of silicon hexachloride is reduced. For example, when the silicon raw material is ferrosilicon or calcium silicon, 120 to 250 ° C. is preferable, and when metallic silicon is 300 to 500 ° C.

As a method for controlling the reaction temperature, any method can be used as long as it can effectively remove the amount of heat generated by the reaction, such as a method of passing a cooling heat medium through the reactor jacket and a method of controlling the temperature of the reactor wall by an electric heater.

After the temperature is raised to a predetermined temperature, chlorine is supplied to a reactor, preferably a gas phase part of the reactor, together with a diluent gas if necessary. Chlorine may be supplied from one location or multiple locations,
Especially when a plurality of supply ports are provided, the supply amount of chlorine can be controlled from the signals of thermometers provided near the respective supply ports, and the temperature control of the entire reactor can be facilitated. So desirable.

The flow direction of chlorine gas may be cocurrent or countercurrent with the transfer direction of the silicon raw material. The chlorine supply rate is as described above.

The end of the reaction can be grasped by measuring the concentration of unreacted chlorine in the waste gas introduced into the waste gas outlet pipe outside the reaction system,
The chlorine supply may be stopped when the chlorine concentration exceeds a predetermined value.

The product containing silicon hexachloride produced by the reaction as described above is usually introduced into the cooling pipe from the product gas outlet of the reactor in a gaseous state, and is obtained as a product liquid after cooling.

The product liquid contains silicon hexachloride, silicon tetrachloride, silicon octachloride, etc. and is purified by a distillation method or the like to obtain silicon hexachloride.

The present invention can be carried out not only as a batch reaction but also as a continuous reaction, but a continuous reaction is preferable for industrial production. In the case of continuous reaction, a silicon raw material continuous supply device and a silicon raw material continuous discharge device may be installed in the vibration reactor.

〔Example〕

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

Example 1 A vibration conveyor type stainless steel reactor with a width of 0.5 m, a height of 0.2 m and a length of 4.0 m as shown in FIG. 1 (with an outer jacket,
Effective heat transfer area 2.0m ² ; Support base 3 and spring 5 are interposed. 1) was equipped with a hopper 16 for supplying a silicon raw material, a tube conveyor 15 for recycling a reaction residue, and the like to produce silicon hexachloride.

Two partition plates 27 of 0.5 m × 0.15 m and 5 mm in thickness are attached to the inside of the reactor. First hopper 16
35 kg of ferron silicon 4 (silicon content of 50% by weight passed through 40 mesh sieve) was charged, and the reactor 1 was oscillated by the oscillator 2 at a frequency of 650 cpm and an amplitude of 5 mm (vibration angle: reactor 1
Ferrosilicon 4 was supplied by a rotary valve 17 set at a supply amount of 750 kg / hr while vibrating under a vibration condition of 60 ° with respect to the horizontal plane. The ferrosilicon 4 in the reactor was transferred by the given vibration, discharged from the silicon raw material outlet pipe 14, and returned to the hopper 16 by the tube conveyor 15 for circulation. The amount of residence of ferrosilicon in the reactor per effective heat transfer area is 12.5 kg / m ² ,
The transfer speed was 2 m / mm.

Then, N ₂ gas is supplied from the dilution gas supply pipe 9 for each 200 / hr.
While flowing, the heat medium was circulated through the outer jacket 10 to heat it, and the temperature was raised to 160 ° C. After that, N ₂ gas is added to each 2
While controlling the reaction temperature to 5 ° C./hr and controlling the reaction temperature to 160 ° C., chlorine was flowed through the chlorine supply pipe 8 at a rate of 500 m / hr for a total of 1.0 m ³ / hr for reaction.

The diameter of the chlorine supply pipe 8 is 20 mmφ and the linear velocity of chlorine is about
It was 0.5 m / sec, but the reaction rate of chlorine during the reaction was almost 9
It was 9 to 99.9%, and the reaction was terminated when the reaction rate of chlorine reached 95%.

The total amount of chlorine supplied was 28.2 m ³ . During the reaction, the temperature was measured at four places in the silicon raw material layer at equal intervals in the reactor length direction, but the difference between the highest temperature and the lowest temperature was almost 2 ° C. or less among the four places. The generated gas and unreacted chlorine are discharged from the generated gas outlet pipe 21 to a sedimentation dust collector 22.
After removing the associated fine powdery substance with, the mixture was passed through the inner pipe of the cooling pipe 23 and cooled with 5 ° C. cold water passed through the outer pipe. The condensed silicon chloride was obtained as a product liquid 25 in the product liquid receiver 24. The amount of the produced liquid obtained by the reaction was 70.7 kg, and the composition was 58.5% by weight of silicon hexachloride, 40.9% by weight of silicon tetrachloride, and 0.6% by weight of higher chlorides (silicon octachloride or more). Reactor 1, hopper 16, tube conveyor 15
The property of the ferrosilicon reaction residue in the etc. is powdery,
There was almost no adhesion to the inner wall of the reactor or the like, and there was no sign of clogging of the produced gas outlet pipe 21 or the like.

When the reaction residue was analyzed, the main component was ferric chloride (anhydrous).
In addition, other unreacted ferrosilicon and metal chlorides such as aluminum chloride due to impurities in the raw ferrosilicon were present.

Unreacted ferrosilicon was 7.3 kg, and the reaction rate of ferrosilicon was 79.1%.

Example 2 In the apparatus of Example 1, a silicon raw material withdrawing port was provided above the tube conveyor 15 and a silicon raw material supply port was provided above the hopper 16, and the partially chlorinated silicon raw material withdrawn from the silicon raw material withdrawing port was washed with water. Silicon hexachloride was continuously produced by a method of recovering and drying unreacted ferrosilicon through the mouth, and then returning to the reaction system again from the silicon raw material supply port.

The reaction was carried out in exactly the same manner as in Example 1 as a step before the continuous reaction. Then, when chlorine gas of 20 m ^{3 was} flowed, the continuous reaction was started, and ferrosilicon was newly added in 1 hour.
Each 1.04 kg was intermittently supplied to the hopper 16 from the silicon raw material supply port on the upper part of the hopper.

During the continuous reaction, N ₂ gas was supplied from the dilution gas supply pipe 9 to each 25
Per hour, while controlling the reaction temperature at 160 ° C, chlorine is supplied from the chlorine supply pipe 8 at a rate of 500 m / hr for a total of 1 m ³ / hr.
It reacted in the sink.

The partially-reacted silicon raw material discharged from the reactor 1 is returned to the hopper 16 by the tube conveyor 15 for recycling, and a part of the silicon raw material is intermittently withdrawn by 2.2 kg per hour from the upper portion of the tube conveyor through the outlet. It was

The extracted partially reacted silicon raw material is treated with water to recover unreacted ferrosilicon, dissolves metal chlorides such as ferric chloride and solid-liquid separates, and the recovered ferrosilicon is dried in a dryer. After drying, it was supplied to the hopper 16 together with new ferrosilicon through the silicon raw material supply port on the upper part of the hopper. The recovered ferrosilicon was intermittently supplied by 0.71 kg per hour.

The continuous reaction was carried out for a total of 100 hours, but the reaction rate of chlorine during the reaction was 99 to 99.9%. During the reaction, the internal temperature of each part of the reactor was measured at 4 points as in Example 1, but the difference between the maximum temperature and the minimum temperature was almost within 2 ° C.

The total amount of supplied chlorine was 121 m ³ , the supplied amount of ferrosilicon was 139 kg, and the amount of the produced liquid was 314.1 kg.
The composition of the product solution is 58.9% by weight of silicon hexachloride and 40.1% of silicon tetrachloride.
% By weight, and 1.0% by weight of higher chlorides (silicon octachloride and above).

The utilization rate of ferrosilicon was about 94% including the loss because unreacted ferrosilicon was recovered and reacted.

After the reaction, the inside of the reactor was inspected, and the properties of the ferrosilicon reaction residue in the reactor 1, the hopper 16, the tube conveyor 15, etc. were powdery, there was almost no adhesion to the inner wall of the reactor, and the produced gas outlet pipe 21 etc. No signs of blockage were noted.

(C) Effect of the Invention The present invention uses a vibrating reactor and chlorinates a silicon raw material while transferring the silicon raw material by the vibration of the reactor, thereby increasing the effective contact area between the silicon raw material and chlorine. The heat exchange efficiency between the silicon raw material and the reactor is improved, and the reaction temperature in the reactor can be easily controlled.

According to the present invention, it is possible to carry out a uniform reaction in the entire reactor, and therefore, in combination with the characteristics of the vibration type reactor, synergistically facilitate the control of the reaction temperature and increase the reaction heat. This enables the reaction to be stably operated on an industrial scale.

Further, in the method of the present invention, if a partition plate is installed in the gas phase part of the reactor, the rate of chlorine passing through is reduced, and at the same time, the diffusion of chlorine into the silicon raw material layer is promoted to increase the reaction rate of chlorine. In addition, it is possible to solve the problem of adhesion to the inner wall of the reactor and clogging of piping.

Further, by circulating all or part of the partially chlorinated silicon raw material transferred and discharged from the silicon raw material outlet to the reactor again, the thickness of the silicon raw material layer in the reactor can be easily reduced. As a result, the heat removal efficiency is improved, and the temperature control is further facilitated. In addition, the utilization rate of the silicon raw material is significantly improved, and it is industrially inexpensive and efficient, and silicon hexachloride can be produced in high yield. It is possible to manufacture.

Further, the utilization rate of the silicon raw material is further improved by returning the silicon raw material to the reactor after performing a treatment of separating the metal chloride by-produced from the silicon raw material from all or part of the silicon raw material returned to the reactor. Further improvement, the method of the present invention becomes industrially more advantageous.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an example of an apparatus for carrying out the method of the present invention. 1 ... Reactor 2 ... Oscillator (crank type oscillator) 3 ... Support base 4 ... Ferrosilicon 5 ... Spring 8 ... Chlorine supply pipe 10 ... External jacket 14 ... Silicon raw material outlet pipe 15 ...... Tube conveyor 16 ...... Hopper (for supplying silicon raw material) 17 ...... Rotary valve 21 ...... Product gas outlet pipe 25 ...... Product liquid

Claims (1)

[Claims] 1. When reacting a silicon raw material selected from a silicon alloy and metallic silicon with chlorine to produce silicon hexachloride,
A method for producing silicon hexachloride, characterized in that a vibrating reactor is used and the reaction is carried out by transferring the silicon raw material from a silicon raw material supply port of the reactor toward an outlet by vibrating the reactor.