JP4029054B2 - Liquid purification device - Google Patents

Description

[0001]
The present invention relates to a liquid purification apparatus that purifies, for example, drainage of a polishing liquid used when mirror polishing silicon.
[0002]
Currently, fine particles such as colloidal silica are contained in the polishing liquid used when mirror-polishing silicon. The particle size is about 0.15 μm, and the purification is performed by adding a flocculant such as polyaluminum chloride and placing it in a thickener, a huge sedimentation tank, for 2 to 3 hours to obtain a supernatant of several centimeters. It is released.
[0003]
[Problems to be solved by the invention]
However, in the next-generation semiconductor that has been operating since FY 2004, the wiring material is changed from aluminum to copper, and the wiring width is reduced from 0.13 μm to 0.09 μm. Along with this, the particle size of colloidal silica, which is an abrasive grain, has come to be used with ultra-fine particles of 50 nm or less, and the treatment of adding a flocculant as in the past, the coagulation sedimentation rate becomes extremely slow and can be dealt with. lost.
For this reason, hollow fiber + vacuum distillation method, osmotic filtration method using UF membrane / MF membrane, osmotic filtration method using ceramic filter, etc. have been studied, but treatment using hollow fiber + vacuum distillation method, The apparatus becomes enormous, and other methods have problems that the apparatus is enormous and sufficient accuracy cannot be obtained.
Furthermore, there was a problem that copper ions mixed in the waste water could not be removed.
For this reason, development of the apparatus which purifies the colloidal silica waste water for next-generation semiconductors and can also remove a copper ion by a simple method has been desired.
[0004]
The present invention has been made to satisfy the conventional requirements as described above.
The invention of [Claim 1] is that in the first step, the magnesium addition means adds 40 ppm or more of magnesium chloride or magnesium sulfate into the liquid to be purified containing the object to be purified. The liquid to be purified is caused to pass through the intergranular gap between adsorbents composed of at least basic magnesium sulfate and magnesium hydroxide and are formed into granules, and the object to be purified is agglomerated, It is an object of the present invention to provide a liquid purification apparatus that removes agglomerated objects to be purified by a sedimentation tank, or removes them by a coarse filter or a centrifuge.
The invention of [Claim 2] is a liquid purification apparatus comprising a PH alkali adjusting means in the first step, wherein the pH value of the liquid to be purified before or after the addition of magnesium is PH9 or more, and the coagulation effect is enhanced. The purpose is to provide.
The invention of [Claim 3] provides a liquid purifier having a higher coagulation effect by setting the amount of magnesium chloride or magnesium sulfate added to the liquid to be purified to 40 ppm to 150 ppm by means of adding magnesium. With the goal.
In the invention of [Claim 4], the first step comprises a PH acidity adjusting means for setting the PH value of the liquid to be purified to PH3 or less, an iron ion adding means for adding iron sulfate or iron chloride to the liquid to be purified, A liquid composed of PH alkali adjusting means having a PH value of PH3 or less and having a PH value of the liquid to be purified to which iron ions are added, PH9 or more, and also removing heavy metal ions in the liquid to be purified An object is to provide a purification device.
The invention of [Claim 5] provides a liquid purification apparatus in which the amount of iron ions added to the liquid to be purified by the iron ion addition means is ½ or more of the heavy metal ions in the liquid to be purified. With the goal.
[Claim 6] In the invention, after adding iron ions into the liquid to be purified by the iron ion adding means, air or oxygen or ozone bubbles are mixed into the liquid to be purified by the bubble mixing means. It is an object of the present invention to provide a liquid purification apparatus that improves the removal efficiency of heavy metal ions.
[0005]
[Means to Solve the Invention]
The invention of [Claim 1] includes a first step of adding 40 ppm or more of magnesium chloride or magnesium sulfate to a liquid to be purified containing an object to be purified by means of magnesium addition means, and magnesium chloride in the first step. Alternatively, the liquid to be purified, to which magnesium sulfate has been added, is allowed to pass through the interstices of the adsorbent composed of at least the crystalline fibers of basic magnesium sulfate and magnesium hydroxide to form a granular shape, and the object to be purified is passed through. A second step of agglomeration, and a third step of removing the object to be purified, which has been agglomerated in the second step, by precipitation in a sedimentation tank, or by a coarse filter or centrifuge In the invention of [Claim 2] realized in the first step, the pH value of the liquid to be purified before or after addition of magnesium is set to PH9 or more in the first step. PH alkali adjusting means is provided to increase the coagulation efficiency.
The invention of [Claim 3] realizes the addition amount of magnesium chloride or magnesium sulfate added to the liquid to be purified by the means for adding magnesium to 40 ppm to 150 ppm.
In the invention of [Claim 4], the first step comprises a PH acidity adjusting means for setting the PH value of the liquid to be purified to PH3 or less, an iron ion adding means for adding iron sulfate or iron chloride to the liquid to be purified, The pH of the liquid to be purified, which has a pH of 3 or less and to which iron ions are added, is configured with PH alkali adjusting means for adjusting the PH value to PH9 or more so that heavy metal ions in the liquid to be purified can be removed.
The invention of [Claim 5] realizes the addition amount of iron ions to be 1/2 or more of heavy metal ions in the liquid to be purified.
In the invention of [Claim 6], after iron ions are added to the liquid to be purified by the iron sulfate addition means, air or oxygen or ozone bubbles are mixed into the liquid to be purified by the bubble mixing means. Increased removal efficiency of heavy metal ions.
[0006]
【Example】
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, in the first step, 40 ppm or more of magnesium chloride or magnesium sulfate is added to the liquid to be purified 1 containing the object to be purified by the magnesium addition means 2. In the second step, the liquid 1 to which magnesium chloride or magnesium sulfate was added in the first step was formed into a granular shape by assembling crystalline fibers of at least basic magnesium sulfate and magnesium hydroxide. For example, colloidal silica having a particle diameter of 30 nm in the liquid to be purified 1 is aggregated through the mutual gaps of the adsorbent 3. In the third step, for example, colloidal silica agglomerated in the second step is removed by precipitation in the precipitation tank 4, or removed by a coarse filter or a centrifuge.
In addition, as shown in FIG. 2, the granular adsorbent 3 is configured in a cylindrical shape having a diameter of 2 mm and a length of 5 mm, for example, between the double metal meshes 6 and 7 set in the container 5, It is filled with a thickness of 20 mm.
Instead of the metal meshes 6 and 7, a filter paper, a porous body, or a filter may be used. Instead of the metal meshes 6, 7, a metal mesh, a filter paper, a porous body, or a filter may be used in combination.
[0007]
FIG. 3 is a photograph of a slurry obtained by diluting 30-fold of NP-6001, a slurry containing 13% colloidal silica having a particle size of 30 nm and 1 to 2% organic matter, and FIG. 4 is a magnesium chloride solution in FIG. Fig. 5 shows a state in which 80 ppm of magnesium chloride was added to the solution shown in Fig. 3 and Fig. 6 shows a state in which the sample was left half-day. Fig. 6 shows that 150 ppm of magnesium chloride was added to the solution shown in Fig. 3. It is a photograph of the state that has been placed for half a day.
In the case of adding 40 ppm of magnesium chloride in FIG. 4, a clear supernatant liquid is obtained although the amount of precipitation is small.
In addition, when 150 ppm of magnesium chloride in FIG. 6 is added, the amount of precipitation is large, but the supernatant is slightly cloudy. This cloudiness can be agglomerated by allowing the adsorbent 3 to pass therethrough.
Similar results were obtained even when magnesium sulfate was added instead of magnesium chloride.
[0008]
In addition, when no powdered magnesium chloride is added to the liquid 1 to be purified and a spherical powder having a diameter of 250 μm shown in FIG. 7 is used as the adsorbent 3, the liquid 1 to be purified is treated at 40 kg after treatment. No precipitate was observed in the liquid.
Further, when 80 ppm of magnesium chloride is added to the liquid 1 to be purified and a spherical powder having a diameter of 250 μm is used as the adsorbent 3, the liquid 1 to be purified is purified when it is sequentially purified to 10 kg, 20 kg, and 30 kg. As shown in the photographs of FIGS. 8, 9, and 10, the later liquid gradually deteriorated the separation between the precipitate and the supernatant after 2 hours of incubation.
In this case, as shown in the photograph of FIG. 11, cracks occurred in the powdery adsorbent 3 shown in FIG. This is because, due to the addition of magnesium chloride, the slurry generated in the liquid 1 to be purified clogs the gap between the adsorbents 3, and cracks are generated in the powdered adsorbent 3. It is thought that 1 passed.
[0009]
For this reason, the adsorbent 3 is formed in the granular form shown in FIG. 2, for example, a cylindrical shape having a diameter of 2 mm and a length of 5 mm, and the mutual gap of the adsorbent 3 is widened. As shown in the photographs of FIG. 12, FIG. 13, FIG. 14, FIG. 15, and FIG. 16, the liquids purified in order of 5t, 1t, 1.5t, 2t, and 2.5t settled after being placed for 2 hours, respectively. The separation between the part and the supernatant was almost stable.
[0010]
Next, three containers 5 containing granular adsorbents 3 were connected in series, and 80 ppm of magnesium chloride was added to the liquid to be purified, and 25 t was processed for 5 to 5 days. As shown, it was separated into a sedimented portion and a transparent supernatant liquid portion in a stable manner for 1 hour.
[0011]
Next, three containers 5 containing granular adsorbents 3 were connected in series, 40 ppm of magnesium chloride was added to the liquid to be purified, and 5 t / day was processed. As a result, as shown in FIG. The precipitate was stably separated into a clear supernatant and a clear supernatant liquid over time.
[0012]
Next, two containers 5 containing granular adsorbents 3 were connected in series, 40 ppm of magnesium chloride was added to the liquid to be purified, and 5 t / day was processed. As a result, as shown in FIG. The precipitate was stably separated into a clear supernatant and a clear supernatant liquid over time.
[0013]
Next, three containers 5 containing the granular adsorbent 3 were connected in series, 30 ppm of magnesium chloride was added to the liquid to be purified, and 5 t / day was processed. As a result, as shown in FIG. The precipitate was not separated into a clear supernatant and a clear supernatant with time.
For this reason, 40 ppm-150 ppm is an appropriate amount for the addition amount of magnesium.
[0014]
FIG. 21 is a block diagram showing another embodiment of the present invention. In the figure, the first step includes a PH alkali adjusting means 9 for adding a potassium hydroxide, caustic soda or the like so that the pH value of the liquid 1 to be purified becomes PH9 or more.
That is, when the pH value of the purification liquid 1 is set to PH9 or more, for example, PH10.5, the colloidal silica can be more stably precipitated.
[0015]
FIG. 22 is a block diagram showing still another embodiment of the present invention. In the figure, the first step is a PH acidity adjusting means 10 for reducing the PH value of the liquid 1 to be purified to PH3 or less, and sulfuric acid having a weight of 1/2 or more of the weight of heavy metal ions contained in the liquid 1 to be purified. Air bubbles such as air, oxygen, and ozone are mixed into the iron ion addition means 11 for adding ferric sulfate or iron chloride such as ferric iron and the liquid to be purified 1 which is PH3 or less and to which iron ions are added. A bubble mixing means 12 for stirring and a PH alkali adjusting means 9 for setting the PH value to PH9 or higher are provided.
Note that the iron value may be added after the PH value of the liquid 1 to be purified is made PH3 or less, or the PH value may be made PH3 or less after the iron ion is added to the liquid 1 to be purified.
[0016]
Further, the bubble mixing means 12 is connected between the container 13 → the first pump 14 → the reverse support valve 15 → the second pump 16 → the throttle valve 17 → the closed loop of the container 13 and between the reverse support valve 15 and the second pump 16. In addition, the compressor 18 and the reversely supported valve 19 are configured.
That is, the liquid in the container 13 is pumped up by the first pump 14, and the liquid fed from the first pump 14 and the compressed air from the compressor 18 are stirred in the second pump 16, For example, a chelating agent contained in the liquid 1 to be purified is replaced with copper sulfate added by the iron ion adding means 11 to remove the copper ions. Is possible.
[0017]
In next-generation semiconductors, copper is used as the wiring. For this reason, about 30 ppm of copper ions are mixed in the liquid 1 to be purified. Moreover, the to-be-purified liquid 1 contains a chelating agent, and copper ions cannot be removed unless the chelating agent is dissociated.
For this reason, the pH value of the liquid 1 to be purified is set to PH3 or less, for example, PH2, by the PH acidity adjusting means 9 in the first step, and, for example, heavy metal ions mixed in the liquid 1 to be purified by the iron ion adding means 11 By adding iron ions such as ferric sulfate having the same concentration as that of ferric sulfate, mixing bubbles with air, oxygen, ozone or the like into the liquid 1 to be purified by the bubble mixing means 12, and stirring the copper ions. Substitution with iron ions is promoted, and then the pH value of the liquid 1 to be purified is set to PH9 or more by the PH alkali adjusting means 8.
As a result, the chelating agent and the copper ion are dissociated, the dissociated copper ion is bonded to the hydroxyl group of the adsorbent 3, the copper ion is flocculated, the floc is aggregated, and then removed to remove the copper ion. From 30 ppm to 0.41 ppm could be achieved.
【The invention's effect】
As described above, according to the invention of [Claim 1], in the first step, 40 ppm or more of magnesium chloride or magnesium sulfate is added to the liquid to be purified containing the object to be purified by means of adding magnesium. In the second step, the liquid to be purified is allowed to pass through the interstices of the adsorbent configured in a granular form by assembling crystalline fibers of at least basic magnesium sulfate and magnesium hydroxide. In the third step, the aggregated objects to be purified are removed by precipitation in a sedimentation tank, or removed by a coarse filter or a centrifuge.
According to the invention of [Claim 2], the first step is provided with PH alkali adjusting means for setting the PH value of the liquid to be purified before or after the addition of magnesium to PH9 or more, thereby enhancing the coagulation effect.
According to the invention of [Claim 3], the addition effect of magnesium chloride or magnesium sulfate added to the liquid to be purified is set to 40 ppm to 150 ppm by the magnesium addition means, thereby further enhancing the coagulation effect.
According to the invention of [Claim 4], the first step includes a PH acidity adjusting means for setting the PH value of the liquid to be purified to PH3 or less, and an iron ion adding means for adding iron sulfate or iron chloride to the liquid to be purified. And PH alkali adjusting means for adjusting the PH value of the liquid to be purified which is made PH3 or less and to which iron ions are added to PH9 or more, and also removes heavy metal ions in the liquid to be purified.
According to the invention of [Claim 5], the amount of iron ions added to the liquid to be purified by the iron ion adding means is more than 1/2 of the heavy metal ions in the liquid to be purified. The heavy metal ions in the liquid to be purified are removed.
According to the invention of [Claim 6], after iron ions are added to the liquid to be purified by the iron ion adding means, air or oxygen or ozone bubbles are mixed into the liquid to be purified by the bubble mixing device, and it is more effective. The heavy metal ions in the liquid to be purified are removed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a liquid purification apparatus according to the present invention.
FIG. 2 is a photograph showing the granular adsorbent shown in FIG.
FIG. 3 is a photograph of a solution obtained by diluting slurry NP-6001 30 times.
4 is a photograph of a state in which 40 ppm of magnesium chloride was added to the solution of FIG. 3 and placed for half a day.
FIG. 5 is a photograph of a state in which 80 ppm of magnesium chloride was added to the solution of FIG. 3 and placed for half a day.
6 is a photograph of a state in which 120 ppm of magnesium chloride was added to the solution of FIG. 3 and placed for half a day.
FIG. 7 is a photograph showing a powdery adsorbent.
FIG. 8 is a photograph showing the state of separation between the precipitate and the supernatant liquid after purifying 10 Kg of the liquid to be purified using a powdery adsorbent and incubating for 2 hours.
FIG. 9 is a photograph showing the state of separation between the precipitate and the supernatant after 2 K of purification of the liquid to be purified using a powdery adsorbent.
FIG. 10 is a photograph showing the state of separation between the precipitate and the supernatant liquid after purifying 30 Kg of the liquid to be purified using a powdery adsorbent and incubating for 2 hours.
FIG. 11 is a photograph showing the outer peripheral surface of the powdery adsorbent after the treatment of FIG.
FIG. 12 is a photograph showing the state of separation between the precipitate and the supernatant after purifying 500 Kg of the liquid to be purified using a granular adsorbent and incubating for 2 hours.
FIG. 13 is a photograph showing the state of separation between the precipitate and the supernatant after purifying the liquid to be purified by 1000 Kg using a granular adsorbent and incubating for 2 hours.
FIG. 14 is a photograph showing the state of separation between the precipitate and the supernatant after purifying 1500 Kg of the liquid to be purified using a granular adsorbent and incubating for 2 hours.
FIG. 15 is a photograph showing the state of separation between the precipitate and the supernatant after purifying 2000 Kg of the liquid to be purified using a granular adsorbent and incubating for 2 hours.
FIG. 16 is a photograph showing the state of separation between the precipitate and the supernatant after purifying 2500 Kg of the liquid to be purified using a granular adsorbent and incubating for 2 hours.
FIG. 17 is a photograph showing the result of continuous treatment of liquid to be purified for 25 tons using a granular adsorbent, adding 80 ppm of magnesium to the liquid to be purified, and connecting three containers containing the adsorbent in series. is there.
FIG. 18 is a photograph showing the result of continuous treatment of the liquid to be purified for 5 tons using a granular adsorbent, adding 40 ppm of magnesium to the liquid to be purified, and connecting three containers containing the adsorbent in series. is there.
FIG. 19 is a photograph showing the result of continuous processing of liquid to be purified for 5 tons using granular adsorbent, adding 40 ppm of magnesium to the liquid to be purified, and connecting two containers containing the adsorbent in series. is there.
FIG. 20 is a photograph showing the result of continuous processing of liquid to be purified for 5 tons using a granular adsorbent, adding 30 ppm of magnesium to the liquid to be purified, and connecting three containers containing the adsorbent in series. is there.
FIG. 21 is a block diagram showing another embodiment of the present invention.
FIG. 22 is a block diagram showing still another embodiment of the present invention.
[Explanation of symbols]
1: Purified liquid 2: Magnesium addition means 3: Adsorbent 4: Precipitation tank 9: PH alkali adjustment means 10: PH acidity adjustment means 11: Iron ion addition means 12: Bubble mixing means

Claims (6)

A first step of adding 40 ppm or more of magnesium chloride or magnesium sulfate into the liquid to be purified containing the object to be purified by means of magnesium addition;
In the first step, the liquid to be purified to which magnesium chloride or magnesium sulfate has been added is placed in the gap between the adsorbents formed into a granular shape by assembling at least crystalline fibers of basic magnesium sulfate and magnesium hydroxide. A second step of passing and agglomerating the object to be purified;
And a third step of removing the object to be purified, which has been agglomerated in the second step, with a sedimentation tank, or with a coarse filter or a centrifuge. A liquid purification apparatus characterized by the above. 2. The liquid purifying apparatus according to claim 1, wherein the first step includes a PH alkali adjusting means for adjusting the PH value of the liquid to be purified before or after the addition of magnesium to PH9 or more. The liquid purifier according to claim 1 or 2, wherein the addition amount of magnesium chloride or magnesium sulfate added by the magnesium addition means is 40 ppm to 150 ppm. The first step includes a PH acidity adjusting means for reducing the PH value of the liquid to be purified to PH3 or less, an iron ion adding means for adding iron sulfate or iron chloride to the liquid to be purified, PH3 or less, and iron 4. The liquid purification apparatus according to claim 1, further comprising a PH alkali adjusting means for adjusting the pH value of the liquid to be purified which has been ionized and added to a pH of 9 or more. 5. The liquid purification apparatus according to claim 4, wherein the amount of iron ions added to the liquid to be purified by the iron ion adding means is ½ or more of the heavy metal ions in the liquid to be purified. 6. The liquid purification apparatus according to claim 4, wherein air or oxygen or ozone bubbles are mixed into the liquid to be purified to which iron ions have been added by the iron ion adding means, using a bubble mixing apparatus.

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