JP2013060334A - Device and method for recovering calcium fluoride, and method for producing fluorine-containing compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for recovering calcium fluoride, which can easily separate calcium fluoride and impurities; and to provide a method for producing a fluorine-containing compound.SOLUTION: The device for recovering calcium fluoride is equipped with: a crushing part for crushing treatment agent containing particles of calcium fluoride generated by treating exhaust gas containing a fluorine-containing compound and particles of the impurities; and a separation part for separating the particles of calcium fluoride from the treatment agent. The crushing part crushes the treatment agent until an average particle diameter of the particles of the impurities becomes smaller than that of the particles of the calcium fluoride.

Description

  Embodiments described below generally relate to a calcium fluoride recovery device, a calcium fluoride recovery method, and a method for producing a fluorine-containing compound.

In the manufacturing process of electronic devices such as semiconductor devices, fluorine-containing compounds such as hydrogen fluoride (HF) and perfluoro compounds (PFC) are used. And the processing agent containing calcium hydroxide (Ca (OH) ₂ ) is used for the process of the exhaust gas containing such a fluorine-containing compound.
Here, since fluorite as a raw material of fluorine has a problem of resource depletion, it is desired to recover and reuse fluorine.
Therefore, a technique has been proposed in which calcium fluoride (CaF ₂ ) is recovered from the used treatment agent and fluorine is recovered from the recovered calcium fluoride.
However, since the used processing agent contains impurities such as metal oxides contained in the processing agent in addition to calcium fluoride, there is a possibility that it is difficult to recover fluorine. Therefore, development of a technique that can easily separate calcium fluoride and impurities has been desired.

Japanese Patent No. 4543629

  The problem to be solved by the present invention is to provide a calcium fluoride recovery device, a calcium fluoride recovery method, and a fluorine-containing compound manufacturing method capable of easily separating calcium fluoride and impurities. is there.

  The calcium fluoride recovery device according to the embodiment includes a pulverizing unit that pulverizes a treatment agent including calcium fluoride particles generated by treating exhaust gas containing a fluorine-containing compound and particles that become impurities. And a separation unit that separates the calcium fluoride particles from the pulverized treatment agent. And the said crushing part grind | pulverizes the said processing agent until the average particle diameter of the particle | grains used as the said impurity becomes smaller than the average particle diameter of the particle | grains of the said calcium fluoride.

It is a schematic diagram for illustrating the particle | grains of the calcium hydroxide and the aluminum oxide particle which are contained in the processing agent in the state which grind | pulverized the processing agent before use. It is a schematic diagram for illustrating the state which grind | pulverized the used processing agent. It is a flowchart for demonstrating the collection method of the calcium fluoride which concerns on 1st Embodiment. It is a flowchart for illustrating the manufacturing method of the fluorine-containing compound which concerns on 2nd Embodiment. It is a block diagram for illustrating the recovery device of calcium fluoride concerning a 3rd embodiment.

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and detailed description is abbreviate | omitted suitably.
[First embodiment]
In the manufacturing process of electronic devices such as semiconductor devices, fluorine-containing compounds such as hydrogen fluoride and perfluoro compounds are used. The exhaust gas discharged after being used for processing in this manufacturing process contains harmful fluorine-containing compounds. For this reason, exhaust gas is treated with a treating agent to make the exhaust gas non-toxic.

In this case, the processing agent used for processing the exhaust gas containing the fluorine-containing compound includes one containing calcium hydroxide (Ca (OH) ₂ ) particles and catalyst particles.
When a treatment agent containing calcium hydroxide particles and catalyst particles is used, the calcium hydroxide particles contained in the treatment agent react with the fluorine-containing compound contained in the exhaust gas. Thus, calcium fluoride particles 102 are generated. Therefore, after the treatment of the exhaust gas, a treatment agent containing calcium fluoride particles 102 generated by treating the exhaust gas containing a fluorine-containing compound and particles that become impurities (hereinafter simply used treatment). Referred to as an agent). Therefore, the used treating agent containing the calcium fluoride particles 102 can be used as a raw material for producing the fluorine-containing compound.

However, the used treatment agent contains particles of metal oxides such as aluminum oxide (Al ₂ O ₃ ) and silicon dioxide (SiO ₂ ) particles that become impurities when producing fluorine-containing compounds. . In this case, particles of metal oxide such as aluminum oxide are contained in the treatment agent as a catalyst, and particles of silicon dioxide are generated in, for example, an etching process.

If the used treating agent contains particles that become impurities, it may be difficult to produce a fluorine-containing compound using the used treating agent as a raw material.
Therefore, in the present embodiment, the calcium fluoride particles 102 are separated from the used treatment agent.

Here, calcium fluoride particles 102 used as a raw material when producing a fluorine-containing compound and aluminum oxide or silicon dioxide particles used as impurities when producing a fluorine-containing compound are different in hardness and eventually brittleness. It becomes.
Therefore, in the present embodiment, the difference in brittleness is utilized to separate the calcium fluoride particles 102 from the used treatment agent.

FIG. 1 is a schematic view for illustrating calcium hydroxide particles and aluminum oxide particles contained in a treatment agent in a state where the treatment agent before use is pulverized.
As shown in FIG. 1, the treatment agent before use includes calcium hydroxide particles 100 and aluminum oxide particles 101.

  Calcium hydroxide particles 100 are included in the treating agent to react with the fluorine-containing compound in the exhaust gas. The aluminum oxide particles 101 are contained in the treatment agent as a catalyst when the fluorine-containing compound in the exhaust gas reacts with the calcium hydroxide particles 100 in the treatment agent.

  When the treatment agent is used for the treatment of the exhaust gas, the fluorine-containing compound in the exhaust gas reacts with the calcium hydroxide particles 100 in the treatment agent, whereby calcium fluoride particles 102 are generated. The

  In this case, the average particle diameter of the generated calcium fluoride particles 102 is about 100 μm or more. Since the aluminum oxide particles 101 are used as a catalyst, there is no significant change from the state in which the aluminum oxide particles 101 were contained in the treatment agent before use. In addition, in the used treatment agent, silicon dioxide particles generated in an etching process or the like may remain in a minute amount.

Here, the Mohs hardness of the calcium fluoride particles 102 contained in the used treatment agent is 4, the Mohs hardness of the aluminum oxide particles 101 is 9, and the Mohs hardness of the silicon dioxide particles is 7.
Therefore, compared with the calcium fluoride particles 102, the aluminum oxide particles 101 and the silicon dioxide particles have high hardness and become brittle.

  Therefore, if the used treatment agent is pulverized, the average particle diameter of the calcium fluoride particles 102 used as a raw material when producing the fluorine-containing compound and the particles that become impurities when producing the fluorine-containing compound The difference between the average particle diameter (for example, aluminum oxide particles 101 and silicon dioxide particles) can be increased. That is, if the used treating agent is pulverized, the particles that become impurities are more fragile than the particles 102 of calcium fluoride, so that the particles that become impurities can be preferentially pulverized.

  If the difference between the average particle diameter of the calcium fluoride particles 102 and the average particle diameter of the particles serving as impurities can be increased, the calcium fluoride particles 102 can be easily separated from the used treatment agent. be able to.

FIG. 2 is a schematic view for illustrating a state in which a used treatment agent is pulverized.
When the used treatment agent is pulverized, the aluminum oxide particles 101 are more fragile than the calcium fluoride particles 102. Therefore, the aluminum oxide particles 101 are pulverized before the calcium fluoride particles 102 are pulverized. Become.
Therefore, as shown in FIG. 2, the difference between the average particle diameter of the calcium fluoride particles 102 and the average particle diameter of the pulverized aluminum oxide particles 101a can be increased. Also, the difference between the average particle diameter of the calcium fluoride particles 102 and the average particle diameter of the pulverized silicon dioxide particles can be increased. In this case, generally, the amount of silicon dioxide particles contained in the used treatment agent is smaller than the amount of aluminum oxide particles 101. Therefore, even if the silicon dioxide particles that have not been crushed remain in the pulverized used treatment agent, it is necessary to ensure a calcium fluoride content suitable for producing a fluorine-containing compound. Can do.

FIG. 3 is a flowchart for illustrating the calcium fluoride recovery method according to the first embodiment.
First, the used processing agent is pulverized (step S1).
For pulverizing the used treatment agent, for example, a pulverization method using a ball mill or the like can be used.
In this case, the used treatment agent can be pulverized until the average particle diameter of the particles that become impurities becomes smaller than the average particle diameter of the calcium fluoride particles 102.
For example, the used treatment agent can be pulverized until the average particle size of the particles as impurities becomes 100 μm or less. Further, if the used treating agent is pulverized until the average particle size of the particles that become impurities becomes 10 μm or less, separation of the calcium fluoride particles 102 described later can be further facilitated.

  The end point detection when the used treatment agent is pulverized can be performed based on the pulverization time obtained in advance through experiments or the like, for example. Further, the end point detection when pulverizing the used processing agent can be performed by inspecting the sample of the pulverized used processing agent.

As described above, as the amount of particles that become impurities, the amount of particles of the material that is contained as a catalyst in the treatment agent before use is the largest. Therefore, the end point detection when pulverizing the used treatment agent can be performed based on the average particle diameter of the particles of the material contained as a catalyst in the treatment agent before use.
For example, as illustrated in FIG. 2, the used treatment agent is pulverized until the average particle diameter of the aluminum oxide particles 101a contained as a catalyst in the treatment agent before use becomes 100 μm or less. Can do. In this case, if the used treatment agent is pulverized until the average particle diameter of the aluminum oxide particles 101a is 10 μm or less, separation of the calcium fluoride particles 102 described later can be further facilitated.

Next, the calcium fluoride particles 102 are separated from the pulverized used treatment agent (step S2).
By pulverizing the used treatment agent, the average particle diameter of the calcium fluoride particles 102 used as a raw material when producing a fluorine-containing compound and particles that become impurities when producing a fluorine-containing compound (for example, oxidation The difference between the average particle diameter of the aluminum particles 101 and the silicon dioxide particles can be increased.
Therefore, for example, the calcium fluoride particles 102 can be easily separated from the pulverized used treatment agent by using a filtration method.

  In addition, when the specific gravity of calcium fluoride and the specific gravity of impurities are different, the calcium fluoride particles 102 can be easily separated from the pulverized used treatment agent by using a centrifugal separation method. Can do. In this case, if the difference between the average particle diameter of the calcium fluoride particles 102 and the average particle diameter of the impurities particles becomes large, separation using a centrifugal separation method becomes easy.

  In addition, when the surface energy of calcium fluoride and the surface energy of impurities are different, the calcium fluoride particles 102 are easily separated from the pulverized used processing agent using the flotation process. can do. In this case, if the difference between the average particle diameter of the calcium fluoride particles 102 and the average particle diameter of the impurities particles becomes large, separation using the flotation method becomes easy.

An appropriate beneficiation method can be appropriately selected according to the difference between the physical properties of calcium fluoride and the physical properties of impurities. Examples of the beneficiation method include a flotation method, a specific gravity method, an electrostatic beneficiation method, and a magnetic beneficiation method.
In addition, it is not necessarily limited to the separation method mentioned above, It can change suitably. Also, different separation methods can be used in combination.

Moreover, the used processing agent may contain particles that become impurities in addition to the particles of the material that was included as a catalyst in the processing agent before use.
For example, the used processing agent may contain particles that become impurities generated in the manufacturing process. In this case, the used processing agent may contain, for example, silicon dioxide particles generated in an etching process or the like. As described above, the amount of impurities contained in the used treatment agent because it is generated in the manufacturing process is generally small. Therefore, it is not always necessary to remove impurities generated in the manufacturing process. A step of removing impurities generated in the process may be further provided.

  Further, the used treatment agent may contain calcium hydroxide particles that have not been reacted with the exhaust gas. Since the amount of calcium hydroxide particles that have not been reacted with the exhaust gas is generally small, it is not always necessary to remove them. However, when the amount of calcium hydroxide particles that have not been reacted with the exhaust gas is large or when it is desired to improve the separation accuracy of the calcium fluoride particles 102, the step of removing the calcium hydroxide particles Can be further provided.

When removing particles that are impurities other than the particles of the material contained as a catalyst in the treatment agent before use, by washing with a solution such as an acid, the material contained as a catalyst Particles that become impurities other than particles can be dissolved. In addition, a solution, dissolution conditions, etc. can be suitably selected according to the material of the particle | grains used as the impurity used as the removal object.
In the case of calcium hydroxide particles that have not reacted with the exhaust gas, calcium fluoride particles 102 may be generated from the calcium hydroxide particles by treatment with hydrofluoric acid.

In addition, the step of removing particles that are impurities other than the particles of the material contained as a catalyst in the treatment agent before use is a step of grinding the used treatment agent before the step of grinding the used treatment agent. And the step of separating the calcium fluoride particles 102 from the pulverized used treatment agent, and / or after the step of separating the calcium fluoride particles 102 from the pulverized used treatment agent. Can be done in
As described above, calcium fluoride can be recovered from the used treatment agent.

[Second Embodiment]
Next, a method for producing a fluorine-containing compound according to the second embodiment is illustrated.
FIG. 4 is a flowchart for illustrating the method for producing a fluorine-containing compound according to the second embodiment.
The method for producing a fluorine-containing compound according to the present embodiment can be carried out following the above-described calcium fluoride recovery method.
That is, first, the calcium fluoride particles 102 are separated from the used treatment agent by using the calcium fluoride recovery method described above (step S10).
Next, a fluorine-containing compound is produced using the separated calcium fluoride particles 102 as a raw material (step S11).
For example, the separated calcium fluoride particles 102 and concentrated sulfuric acid can be mixed and heated to produce hydrogen fluoride.
In addition, for example, hydrogen fluoride is produced using the separated calcium fluoride particles 102 as a raw material, and the produced hydrogen fluoride and carbon tetrachloride are reacted using a catalyst to produce tetrafluoromethane (CF ₄ ). Can be manufactured.

In this manner, hydrogen fluoride can be produced using the separated calcium fluoride particles 102 as a raw material, or another fluorine-containing compound can be produced using the produced hydrogen fluoride as a raw material.
In addition, since a well-known technique can be applied to the manufacturing process and process conditions of a fluorine-containing compound, detailed description is abbreviate | omitted.
As described above, calcium fluoride can be recovered from the used treatment agent, and a fluorine-containing compound can be produced from the recovered calcium fluoride.

[Third embodiment]
FIG. 5 is a block diagram for illustrating the calcium fluoride recovery apparatus according to the third embodiment.
As shown in FIG. 5, the collection device 1 is provided with a pulverization unit 2 and a separation unit 3.

The pulverizing unit 2 pulverizes the used processing agent supplied by the conveying unit 4.
As the pulverizing unit 2, for example, a material that pulverizes a solid substance such as a ball mill can be appropriately selected.
In this case, the pulverizing unit 2 can pulverize the used treatment agent until the average particle diameter of the particles that are impurities becomes smaller than the average particle diameter of the calcium fluoride particles 102.
For example, the used treatment agent can be pulverized until the average particle size of the particles as impurities becomes 100 μm or less. Further, if the used treatment agent is pulverized until the average particle diameter of the particles as impurities becomes 10 μm or less, the separation of the calcium fluoride particles 102 can be further facilitated.

The end point detection when the used treatment agent is pulverized can be performed based on the pulverization time obtained in advance through experiments or the like, for example. Further, the end point detection when pulverizing the used processing agent can be performed by inspecting the sample of the pulverized used processing agent.
The used processing agent that has been pulverized is supplied to the separation unit 3 by the transport unit 5.
In addition, since the detail regarding grind | pulverizing a used processing agent can be made to be the same as that of what was illustrated in the collection | recovery method of calcium fluoride, description is abbreviate | omitted.

The separation unit 3 separates the calcium fluoride particles 102 from the pulverized used treatment agent.
As the separation unit, for example, one that separates a solid substance using a separation method such as a filtration method can be appropriately selected.
For example, a filtration device capable of performing a filtration method, a centrifugal separation device capable of performing a centrifugal separation method, a mineral processing device capable of performing a mineral separation method such as a flotation method can be appropriately selected.

  In addition, since it can be the same as that of what was illustrated in the collection | recovery method of calcium fluoride about the detail regarding isolate | separating the particle | grains 102 of calcium fluoride from the grind | pulverized used processing agent, description is abbreviate | omitted.

The separated calcium fluoride particles 102 are carried out by the transport unit 6.
The conveyance part 6 can be made to convey the particle | grains 102 of the calcium fluoride isolate | separated toward the manufacturing apparatus which manufactures a fluorine-containing compound.

  On the other hand, the separated particles that are impurities are carried out by the transport unit 7.

According to the embodiments exemplified above, a calcium fluoride recovery device, a calcium fluoride recovery method, and a fluorine-containing compound manufacturing method capable of easily separating calcium fluoride and impurities can be realized. Can do.
As mentioned above, although several embodiment of this invention was illustrated, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

  DESCRIPTION OF SYMBOLS 1 Recovery apparatus, 2 grinding | pulverization part, 3 separation part, 4-7 conveyance part, 102 calcium fluoride particle, 101 aluminum oxide particle, 101a grind | pulverized aluminum oxide particle

Claims (5)

A pulverizing unit for pulverizing a treatment agent containing calcium fluoride particles generated by treating exhaust gas containing a fluorine-containing compound and particles that become impurities;
A separation unit for separating the calcium fluoride particles from the pulverized treatment agent;
With
The said grinding | pulverization part is a calcium fluoride recovery apparatus which grind | pulverizes the said processing agent until the average particle diameter of the particle | grains used as the said impurity becomes smaller than the average particle diameter of the particle | grains of the said calcium fluoride.   2. The calcium fluoride recovery device according to claim 1, wherein the pulverizing unit pulverizes the treatment agent until an average particle size of the particles serving as the impurities becomes 100 μm or less. Pulverizing a treating agent containing calcium fluoride particles generated by treating exhaust gas containing a fluorine-containing compound and particles that become impurities;
Separating calcium fluoride particles from the pulverized treating agent;
With
In the step of pulverizing the treating agent, the calcium fluoride is recovered by pulverizing the treating agent until an average particle size of the particles serving as the impurities is smaller than an average particle size of the calcium fluoride particles.   The method for recovering calcium fluoride according to claim 3, wherein in the step of pulverizing the treatment agent, the treatment agent is pulverized until an average particle size of the particles as impurities becomes 100 μm or less.   A treatment agent comprising calcium fluoride particles produced by treating an exhaust gas containing a fluorine-containing compound using the calcium fluoride recovery method according to claim 3 or 4, and particles serving as impurities. A method for producing a fluorine-containing compound, comprising separating the calcium fluoride particles from the particle and producing a fluorine-containing compound using the separated calcium fluoride particles as a raw material.

Images