JP2004107148A - Method and apparatus for electrolytic refining treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for electrolytic refining treatment, wherein a quartz molding is prevented from being deformed in the electrolytic refining treatment and the reliability in the treatment is enhanced. <P>SOLUTION: In the apparatus for electrolytic refining treatment, the quartz molding S is refined by applying a voltage to the molding to move and remove the impurities in the molding while heating the quartz molding S in a furnace body 2. In the apparatus, the quartz molding S is placed on a placing table 4 so that the longitudinal direction of the molding S is horizontal, and the voltage is applied to the molding S in such a horizontal state. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrolytic purifying apparatus and an electrolytic purifying method for purifying a quartz molded body by performing an electrolytic treatment.
[0002]
[Prior art]
In general, quartz products such as a quartz furnace tube and a crucible for pulling a silicon single crystal are made of natural quartz, so that it is inevitable that aluminum, alkali metal or alkaline earth metal is mixed as a trace impurity. Was. When such a quartz product (quartz molded body) is used at a high temperature, the viscosity is reduced and deformation occurs. In addition, the quartz molded body described above cannot be used for a long time because devitrification is promoted.
It is known that as a cause of such devitrification and deformation, impurities in the quartz molded article are largely affected, and among these impurities, alkali metals such as Na, K, and Li and copper are particularly greatly affected. In order to solve this problem, it has been conventionally performed to remove impurities in a quartz molded body using an electrolytic purification apparatus.
[0003]
This conventional electrolytic purification apparatus will be described with reference to FIG.
In FIG. 2, the electrolytic purification apparatus denoted by reference numeral 21 includes a furnace body 22, heating elements 23a and 23b, and electrodes 24a and 24b.
The furnace body 22 is formed of a box in which the longitudinal direction of the quartz molded body S can be accommodated vertically. The furnace body 22 is provided with a temperature measuring means 25 for measuring the temperature inside the furnace body 22. The temperature measuring means 25 includes a thermocouple 25a and a protection tube 25b, and is connected to the temperature control means 26.
[0004]
The heating elements (heaters) 23a and 23b are disposed in the furnace body 22 and are configured to heat the quartz molded body S in the furnace body 22. The heating elements (heaters) 23a and 23b are connected to the temperature control means 26, and control the amounts of heat generated by the heating elements 23a and 23b by the temperature control means 26 based on the temperature measured by the thermocouple 25a. It is configured to set the internal temperature to a predetermined temperature.
[0005]
Each of the electrodes 24a and 24b is configured so that one end thereof faces the inside of the furnace body 22 and a voltage from a DC power supply 27 is applied to the quartz molded body S to electrolyze the quartz molded body S. Have been.
The electrode 24a is a positive electrode having a positive electrode plate 24A, is disposed above the quartz compact S, and is held by the furnace body 22 via a holding tube 28. The electrode 24b is a negative electrode having a negative electrode plate 24B, and is disposed below the quartz formed body S.
[0006]
The holding pipe 28 is attached to an upper end of the furnace body 22 and is connected to an inert gas supply means 29 via a gas blowing pipe 30. The electrode 24a is configured to be inserted and held.
The inert gas supply unit 29 includes a flow rate setting unit 29a, and is configured to supply the inert gas into the holding tube 28 at a predetermined speed.
[0007]
Next, the electrolytic purification treatment of the quartz compact S using the electrolytic purification treatment apparatus configured as described above will be described.
First, the quartz molded body S is housed in a vertical position at a predetermined position in the furnace body 22. Subsequently, the heating elements 23a and 23b are heated, and a high voltage is applied from the DC power supply 27 to both the electrodes 24a and 24b.
As described above, when the quartz molded body S is heated by the heating elements 23a and 23b and a high voltage is applied by the DC power supply 27, impurities in the quartz molded body S, for example, an alkali metal or copper become the negative electrode 24b. It moves to the (negative electrode plate 24B) side. Then, when a part of the quartz compact S containing the impurities is removed, a purified quartz compact can be obtained.
[0008]
[Problems to be solved by the invention]
By the way, in the electrolytic purifying apparatus described above, the quartz molded body is housed in the furnace so that the longitudinal direction of the quartz molded body is vertical. There is a problem that the shape may be deformed and the reliability in the electrolytic purification treatment is reduced.
[0009]
Further, when the quartz molded body is a quartz molded body produced by oxyhydrogen melting, since the OH group content is large, by applying a high pressure for a considerably long time, the purification of copper and alkali metal can be performed. The effect is increased, and it is possible to purify iron that moves slowly.
On the other hand, when the quartz molded body is a quartz molded body produced by electric vacuum melting, the OH group content is very high as compared with a quartz molded body produced by oxyhydrogen fusion. Few. Therefore, when the metal element moves to a certain level, the metal element becomes insulated, and iron having a low moving speed does not move, remains in the quartz molded body, and cannot be purified.
[0010]
The present invention has been made in order to solve such a technical problem, and can prevent deformation of a quartz molded body during electrolytic purification processing, and can thereby increase reliability in electrolytic purification processing. An object of the present invention is to provide an electrolytic purification apparatus.
Further, the present invention has been made in order to solve such a technical problem, in any case of a quartz molded body manufactured by oxyhydrogen melting, or a quartz molded body manufactured by electric vacuum melting Another object of the present invention is to provide an electrolytic purification treatment method capable of further purifying the quartz molded body with higher purity.
[0011]
[Means for Solving the Problems]
The electrolytic purification apparatus according to the present invention, which has been made to achieve the above object, heats a quartz compact in a furnace and applies a voltage to the quartz compact to move impurities in the quartz compact. In an electrolytic purification apparatus for purifying a quartz molded body by removing the impurities, the quartz molded body is placed on a mounting table so that the longitudinal direction of the quartz molded body is horizontal, and in this horizontal state, It is characterized in that a voltage is applied to the quartz molded body.
[0012]
As described above, in the electrolytic purification apparatus according to the present invention, the quartz molded body is placed on the mounting table such that the longitudinal direction of the quartz molded body is horizontal, and a voltage is applied to the quartz molded body in the horizontal state. Applied.
For this reason, the influence of the weight of the quartz molded body can be suppressed as much as possible, the adverse effect that the quartz molded body is deformed by heat during the electrolytic purification treatment can be prevented, and the reliability in the electrolytic purification treatment can be improved.
[0013]
Here, the concave portion formed on the upper surface of the mounting table, a negative electrode plate housed in the concave portion, and a glass powder disposed on the upper surface of the negative electrode plate, the outer peripheral surface of the quartz molded body, It is desirable to be electrically connected to the negative electrode plate via the glass powder.
As described above, since the outer peripheral surface of the quartz molded body is electrically connected to the negative electrode plate via the glass powder, impurities moving inside the quartz molded body are trapped by the glass powder. Therefore, it is not necessary to grind the portion where the impurities remain, and the whole quartz molded body can be used as a high-purity final product, thereby preventing waste.
[0014]
In addition, a positive electrode plate may be provided above the concave portion formed on the upper surface of the mounting table, and an outer peripheral surface of the quartz molded body may be electrically connected to the positive electrode plate via the silicon carbide powder. desirable.
[0015]
Further, it is preferable that a regulating member for holding an outer peripheral surface of the quartz molded body is provided above the mounting table.
As described above, since the outer peripheral surface of the quartz molded body is held by the regulating member, it is possible to further prevent the adverse effect that the quartz molded body is deformed due to heat during the electrolytic purification treatment, and further improve the reliability in the electrolytic purification treatment. Can be done.
[0016]
In order to achieve the above object, the electrolytic purification treatment method according to the present invention is to heat a quartz molded body in a furnace and apply a voltage to the quartz molded body to move impurities in the quartz molded body. An electrolytic purification treatment method for purifying a quartz molded body by removing the impurities, wherein a conductive ion serving as a carrier ion of the impurity transfer is contained in an inert gas, and the quartz is formed in the inert gas atmosphere. The method is characterized in that the compact is heated and a voltage is applied to the quartz compact.
[0017]
As described above, since the inert gas contains conductive ions serving as carrier ions for the transfer of impurities, it is possible to purify even a quartz compact having a very small OH group content. That is, an inert gas containing conductive ions is supplied into the furnace until the slow moving iron moves to the negative electrode side, and after the iron moves to the negative electrode, an inert gas containing no conductive ions is supplied into the furnace. And purify it.
[0018]
In addition, the electrolytic purification treatment method according to the present invention, which has been made to achieve the above object, includes heating a quartz molded body in a furnace, applying a voltage to the quartz molded body, and removing impurities in the quartz molded body. An electrolytic purification treatment method for purifying a quartz compact by removing the impurities by moving the silicon carbide powder containing conductive ions serving as carrier ions for the impurity transfer, or a material powder serving as the conductive ions. And contacting the silicon carbide powder with the quartz molded body, disposing a positive electrode plate on the upper part thereof, and applying a voltage to the quartz molded body by disposing a negative electrode plate below the quartz molded body. I have.
[0019]
As described above, since the silicon carbide powder containing conductive ions serving as carrier ions for impurity transfer or the material powder and silicon carbide powder serving as the conductive ions are brought into contact with the quartz molded body, the OH group content is reduced. It is possible to purify even a very small amount of quartz molded body.
For example, by using silicon carbide powder containing a predetermined amount of Cu ions as conductive ions, iron having a low moving speed can be moved to the negative electrode side by the conductive ions. Then, after the conductive ions have been consumed, by continuing the processing, a purified quartz molded body can be obtained.
[0020]
The conductive ions are desirably one or more ions selected from Ag ions, Li ions, Cu ions, Na ions, and F ions.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an electrolytic purification apparatus and method to which the present invention is applied will be described based on an embodiment shown in the drawings. 1 (a) and 1 (b) are a front view and a side view showing an electrolytic purification apparatus according to an embodiment of the present invention. In FIG. 1 (a) and FIG. Detailed description is omitted.
[0022]
In FIG. 1A, the electrolytic purification apparatus denoted by reference numeral 1 includes a furnace body 2, heating elements 23a and 23b, electrodes 3a and 3b, and a mounting table 4.
The furnace body 2 is a box housing a mounting table 4 on which a cylindrical quartz molded body S is mounted. The cylindrical quartz molded body S is mounted on the mounting table 4 so that its axis (longitudinal direction) is horizontal.
Further, as shown in FIG. 1B (not shown in FIG. 1A), a regulating member having an inner peripheral surface 5a above the mounting table 4 and adapted to the outer peripheral surface of the quartz molded body S. 5 are provided.
The regulating member 5 is for preventing deformation of the quartz molded body S due to heat at the time of electrolytic purification treatment, and is provided in a pair with the upper end of the mounting table 4 in contact with the lower end. It is provided to hold from both sides.
The restricting member 5 is made of a silicon carbide material, and is configured such that, after the quartz compact S is placed on the mounting table 4, the outer peripheral surface of the quartz compact S is moved from both sides and held.
[0023]
Further, the furnace body 2 is provided with a temperature measuring means 25 for measuring the internal temperature, similarly to the conventional furnace body 22.
Each of the electrodes 3a and 3b faces one end of the furnace body 2 in the same manner as the conventional electrodes 24a and 24b, and applies a voltage (10 to 50 KV) from the DC power supply 27 to the quartz molded body. S is applied so as to electrolyze the quartz compact S.
[0024]
A plurality of the electrodes 3a are provided in the longitudinal direction of the quartz molded body S, and these electrodes 3a are held by the furnace body 2 via the holding tube 28.
The electrodes 3a are positive electrode having a plurality of positive electrode plates 3A ₁ made of SiC plate or a carbon plate, a common plate 3A ₂ made of SiC plate or a carbon plate connects the respective positive electrode plates 3A ₁ (SiC). The electrode 3a is electrically connected to the outer peripheral surface of the quartz compact S via silicon carbide powder (SiC 180) a.
[0025]
In FIG. 1A, one electrode 3a is shown in detail, and other electrodes 3a and another holding tube 28 are omitted. Further, said silicon carbide powder is plated powder on the outer peripheral surface upper portion of the quartz moldings S, it is laminated while pressing a thin plate jig, a positive electrode plate 3A _1, are fixed by the common plate 3A _2.
[0026]
On the other hand, the electrode 3b is provided in a recess 4a formed in the mounting table 4. The concave portion 4a of the mounting table 4 is formed as a space having a size in which the DURA blanket 6 that houses the negative electrode plate 3B is housed. Therefore, the negative electrode plate 3 </ b> B is mounted on the recess 4 a of the mounting table 4 via the Dura blanket 6.
The electrode 3b is a negative electrode having a negative electrode plate 3B made of platinum, and is electrically connected to the outer peripheral surface of the quartz molded body S via the purified glass powder b provided on the upper surface of the negative electrode plate 3B. Connected.
[0027]
The thickness of the glass powder b is preferably 5 to 20 mm. If the thickness is smaller than 5 mm, it is not preferable because the negative electrode side of the quartz molded body S is devitrified. On the other hand, when the thickness is larger than 20 mm, the electric resistance increases and the electrolysis time becomes longer, which is not preferable.
[0028]
As described above, the reason for using the silicon carbide powder a and the glass powder b is that it is not necessary to change the shape of the electrode plate even if the quartz compact has a relatively complicated shape. That is, the positive electrode made of silicon carbide powder and the glass powder on the negative electrode side can freely change shapes in accordance with the complicated shape of the quartz formed body S.
[0029]
With the above configuration, the electrolytic purification treatment of the quartz molded body S is performed as follows.
That is, after placing the quartz molded body S on the mounting table 4 in the furnace body 2 so that the longitudinal (axial) direction of the quartz molded body S is horizontal, the quartz molded body S is heated at a temperature of 1200 ° C. or more, A DC voltage of 10 to 50 KV is applied to the quartz molded body S for 60 hours.
At this time, conductive ions such as Ag ions, Li ions, Cu ions, Na ions, and F ions serving as carrier ions that substitute for H ⁺ of the OH group are contained in the inert gas and supplied into the furnace.
[0030]
As a result, metal impurities such as alkali metals of Li, K, and Na and copper in the quartz compact S move to the negative electrode side, and are trapped in the glass powder b below the quartz compact S.
In particular, since the conductive ions such as Ag ions, Li ions, Cu ions, Na ions, and F ions serving as carrier ions are contained in the inert gas and supplied into the furnace, the quartz compact S having a small number of OH groups is provided. In this case, iron having a low moving speed can be moved to the negative electrode side.
[0031]
Then, after applying a DC voltage of 10 to 50 KV to the quartz molded body S for 5 hours, an inert gas not containing the conductive ions in the inert gas is supplied into the furnace, and the purification treatment is further performed for 30 hours. Do.
As a result, the conductive ions in the quartz compact S taken from the inert gas are trapped in the glass powder b on the negative electrode side.
[0032]
As described above, since the impurities come out of the quartz formed body S and are trapped in the glass powder b, the whole quartz formed body S becomes high purity, and the whole quartz formed body S becomes a high-purity final product. Because it can be used, there is no waste.
As an example, a purified quartz molded body having an alkali metal of Li, K, and Na at 0.5 ppm or less and Cu at 0.03 ppm or less, and having a viscosity of 10 ¹² poise or more at 1200 ° C. Obtainable.
[0033]
In the purifying process, an inert gas always flows between the holding tube 28 and the positive electrode 3a. This inert gas flows at a flow rate of 10 to 15 mm / sec. By flowing the inert gas in this manner, the temperature of the holding tube 28 can be cooled to about 400 ° C., and the insulating effect between the holding tube 28 and the positive electrode 3b can be enhanced. That is, the insulation resistance can be made about 108 Ω · cm.
If the flow rate of the inert gas is less than 10 mm / sec, the holding tube 28 cannot be sufficiently cooled, and the insulating effect of the holding tube 28 will be deteriorated. On the other hand, if the flow rate is higher than 15 mm / sec, not only the positive electrode 3a but also the upper part of the quartz compact S is cooled, and the efficiency of electrolysis deteriorates.
By thus cooling with an inert gas, the insulating effect between the positive electrode 3a and the holding tube 28 can be enhanced, and no current flows from the holding tube 28 to the furnace body 2. Therefore, the insulating property of the whole furnace body 2 is increased, and no current is caused, so that the quartz molded body can be efficiently electrolyzed.
[0034]
In addition, as described above, the silicon carbide powder a containing the conductive ions serving as the carrier ions for the impurity transfer is brought into contact with the quartz compact S without causing the conductive ions to be contained in the inert gas. The plate 3A ₁ and the common plate 3A ₂ may be arranged, and the negative electrode plate 3B may be arranged below the quartz molded body S via the refined glass powder b to apply a voltage to the quartz molded body S. .
[0035]
As described above, since the silicon carbide powder containing conductive ions serving as carrier ions for impurity transfer is brought into contact with the quartz compact, it is possible to purify even a quartz compact having a very small OH group content. it can.
For example, by using silicon carbide powder doped with a predetermined amount of Cu ions as conductive ions, conductive ions are supplied until iron having a low moving speed moves to the negative electrode side. Then, by continuing the treatment after the conductive ions have been consumed, a purified quartz molded body can be obtained.
[0036]
Note that, for example, a small amount of Cu powder or the like may be mixed into the silicon carbide powder without doping the conductive ions. That is, the material powder to be the conductive ions and the silicon carbide powder a are brought into contact with the quartz molded body S, and the positive electrode plate 3A ₁ and the common plate 3A ₂ are arranged on the upper part thereof. A negative electrode plate 3B may be arranged via the refined glass powder b, and a voltage may be applied to the quartz molded body S.
[0037]
As described above, in the present embodiment, even if the size of the quartz molded body S in the longitudinal direction becomes large, it is possible to prevent the quartz molded body S from being deformed at the time of the electrolytic purification treatment, and to improve the reliability in the electrolytic purification treatment. Can be enhanced. In addition, when the quartz molded body S has a long dimension in the longitudinal direction such as an optical fiber ingot, it can be particularly effectively applied.
Further, in the present embodiment, at the time of electrolytic purification, conductive ions serving as carrier ions that substitute for H ⁺ of the OH group are supplied to the quartz molded body S, so that the conductivity of the quartz molded body S is increased, Impurities such as Fe having a low moving speed can be moved and removed.
[0038]
In the present embodiment, Ag ions, Li ions, Cu ions, Na ions, and F ions have been described as the conductive ions. However, the present invention is not limited thereto, and other types of conductive ions or the above-described conductive ions may be used. It may be one or more ions selected from Ag ions, Li ions, Cu ions, Na ions, and F ions.
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the quartz molded body from being deformed at the time of the electrolytic purification treatment, and to thereby enhance the reliability of the electrolytic purification treatment.
Further, according to the present invention, in any case of a quartz molded body manufactured by oxyhydrogen melting or a quartz molded body manufactured by electric vacuum melting, the quartz molded body is further purified to a higher purity. Can be.
[Brief description of the drawings]
FIGS. 1 (a) and 1 (b) are a front view and a side view showing an electrolytic purification apparatus according to an embodiment of the present invention.
FIG. 2 is a sectional view showing a conventional electrolytic purification apparatus.
DESCRIPTION OF SYMBOLS 1 Electrolytic purification apparatus 2 Furnace body 3a Positive electrode 3b Negative electrode 3A ₁ Positive electrode plate 3A ₂ Common plate 3B Negative electrode plate 4 Mounting table 4a Depression 5 Regulation member 5a Inner peripheral surface 6 Dura blanket 23a, 23b Heating element 25 Temperature measurement Means 25a Thermocouple 25b Protective tube 26 Temperature control unit 27 DC power supply 28 Holding tube 29 Inert gas supply unit 29a Flow rate setting unit 30 Gas blowing tube a Silicon carbide powder b Glass powder S Quartz compact

Claims (7)

In an electrolytic purification treatment apparatus for heating a quartz molded body in a furnace, applying a voltage to the quartz molded body to move impurities in the quartz molded body, and removing the impurities, thereby purifying the quartz molded body. ,
An electrolytic purification apparatus characterized in that a quartz molded body is placed on a mounting table so that the longitudinal direction of the quartz molded body is horizontal, and a voltage is applied to the quartz molded body in a horizontal state. A concave portion formed on the upper surface of the mounting table, a negative electrode plate housed in the concave portion, and a glass powder disposed on the upper surface of the negative electrode plate,
The electrolytic purification apparatus according to claim 1, wherein an outer peripheral surface of the quartz molded body is electrically connected to a negative electrode plate via the glass powder. A positive electrode plate disposed above a concave portion formed on the upper surface of the mounting table, wherein an outer peripheral surface of the quartz molded body is electrically connected to the positive electrode plate via the silicon carbide powder. The electrolytic purification apparatus according to claim 2. The electrolytic purification apparatus according to any one of claims 1 to 3, wherein a regulating member for holding an outer peripheral surface of the quartz molded body is provided above the mounting table. By heating the quartz molded body in the furnace, applying a voltage to the quartz molded body to move impurities in the quartz molded body, and removing the impurities, the electrolytic purification method for purifying the quartz molded body. So,
Conductive ions serving as carrier ions for the impurity transfer are contained in the inert gas in the furnace, and the quartz molded body is heated in the inert gas atmosphere, and a voltage is applied to the quartz molded body. Electrolytic purification method. By heating the quartz molded body in the furnace, applying a voltage to the quartz molded body to move impurities in the quartz molded body, and removing the impurities, the electrolytic purification method for purifying the quartz molded body. So,
The silicon carbide powder containing conductive ions serving as carrier ions for the impurity transfer or the material powder serving as the conductive ions and the silicon carbide powder are brought into contact with the quartz molded body, and a positive electrode plate is disposed thereon, A voltage is applied to the quartz molded body by disposing a negative electrode plate below the molded body. 7. The electrolytic purification process according to claim 5, wherein the conductive ions are one or more ions selected from Ag ions, Li ions, Cu ions, Na ions, and F ions. Method.

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