TWI798413B - Treating method and treating device for polarizer manufacturing waste liquid - Google Patents

Abstract

The object of the present invention is to provide a treatment device for polarizer manufacturing waste liquid, which can efficiently recover high-quality potassium iodide solution from polarizer manufacturing waste liquid. The solution is a treatment device for polarizer manufacturing waste liquid, which can recover potassium iodide from polarizer manufacturing waste liquid, and it has the following devices: a first processing device, which concentrates the polarizer manufacturing waste liquid and conducts crystallization to obtain A precipitate is generated, and the precipitate is separated from solid and liquid to generate a potassium iodide solution with reduced impurities including boron and polyvinyl alcohol; the first impurity adsorption device is to make the polyvinyl alcohol adsorbent adsorb the obtained potassium iodide solution. The polyvinyl alcohol; and the second impurity adsorption device is to make the boron selective adsorption resin adsorb the remaining boron in the potassium iodide solution after passing through the first impurity adsorption device.

Description

Treatment method and treatment device for polarizing plate manufacturing waste liquid

The present invention relates to a processing method and a processing device for a polarizing plate manufacturing waste liquid, and more specifically relates to a polarizing plate manufacturing waste liquid processing method for recovering potassium iodide from the waste liquid generated in the manufacturing steps of a polarizing plate and Processing device.

Background of the invention

Waste liquid generated during the manufacturing process of polarizing plates used in liquid crystal displays contains inorganic components such as iodine, boron, and potassium, and organic components such as polyvinyl alcohol (PVA). subject to discussion.

For example, Patent Document 1 discloses a treatment method for polarizer manufacturing waste liquid, which has the following steps: a concentration step, which is to evaporate and concentrate the polarizer manufacturing waste liquid to generate precipitates containing boric acid and polyvinyl alcohol; cooling crystallization step , is to cool and crystallize the polarizer manufacturing waste liquid after evaporation and concentration; and the solid-liquid separation step is to recover the filtrate after solid-liquid separation of the precipitate.

Prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2017-209607

Summary of the invention

According to the treatment method of the above-mentioned polarizing plate manufacturing waste liquid, most of the impurities such as boron and PVA contained in the polarizing plate manufacturing waste liquid can be removed. In terms of quality, there is still room for further improvement.

Therefore, the purpose of the present invention is to provide a treatment method and treatment device for polarizing plate manufacturing waste liquid, which can efficiently recover high-quality potassium iodide solution from polarizing plate manufacturing waste liquid.

The aforesaid object of the present invention is achieved through a kind of processing method of polarizing plate manufacturing waste liquid, and the processing method of this polarizing plate manufacturing waste liquid is to recover potassium iodide from polarizing plate manufacturing waste liquid, and it has the following steps: the first processing step, Crystallization is carried out after concentrating the waste liquid from the manufacture of polarizing plates to generate precipitates, and the precipitates are separated into solid and liquid to generate a potassium iodide solution with reduced impurities including boron and polyvinyl alcohol; the first impurity adsorption step is The polyvinyl alcohol adsorbent adsorbs the polyvinyl alcohol remaining in the obtained potassium iodide solution; and the second impurity adsorption step is to make the resin selectively adsorbing boron adsorb the boron remaining in the potassium iodide solution after the aforementioned first impurity adsorption step .

The treatment method of the polarizing plate manufacturing waste liquid is suitable for the aforementioned first A second treatment step is provided between the treatment step and the aforementioned first impurity adsorption step, and the second treatment step is to further reduce the aforementioned impurities in the potassium iodide solution obtained in the aforementioned first treatment step.

The aforementioned 2nd processing step may have the following steps: further concentrating the potassium iodide solution obtained in the aforementioned 1st processing step to precipitate potassium iodide crystals; making the separated potassium iodide crystals solid-liquid separation step; The step of washing the crystals and recovering the potassium iodide crystals from which impurities have been removed; the step of dissolving the recovered potassium iodide crystals into a solvent to generate a potassium iodide solution. At this time, it is better to have a step of filtering the impurity, which is precipitated by the endothermic reaction of potassium iodide crystal dissolving, which reduces the saturated solubility of the solvent.

Alternatively, the aforementioned second treatment step may include a step of removing calcium borate precipitates generated by reacting boron contained in the potassium iodide solution with calcium ions. At this time, the aforementioned second treatment step should further include a step of removing calcium carbonate precipitates, which are produced by reacting calcium ions remaining in the potassium iodide solution with carbonate ions.

In the potassium iodide solution for the aforementioned first impurity adsorption step, the concentration of boron is preferably 100-1000 mg/L, and the concentration of polyvinyl alcohol is preferably 100-500 mg/L in terms of TOC.

Also, the aforementioned object of the present invention is achieved through a treatment device for waste liquid from polarizer manufacturing, which is to recover potassium iodide from waste liquid in polarizer manufacture, and it is equipped with the following devices: the first treatment The device is to crystallize the polarizing plate manufacturing waste liquid to form a precipitate after concentrating the waste liquid, and separate the solid and liquid of the precipitate to generate Potassium iodide solution in which the impurities of polyvinyl alcohol have been reduced; the first impurity adsorption device is to make the polyvinyl alcohol adsorbent absorb the residual polyvinyl alcohol in the obtained potassium iodide solution; and the second impurity adsorption device is to selectively adsorb boron The resin adsorbs boron remaining in the potassium iodide solution after passing through the aforementioned first impurity adsorption device. The processing device for waste liquid from the production of polarizing plates preferably includes a second processing device, which can further reduce the aforementioned impurities in the potassium iodide solution obtained in the aforementioned first processing device.

According to the present invention, it is possible to provide a processing method and a processing device for polarizing plate manufacturing waste liquid, which can efficiently recover high-quality potassium iodide solution from polarizing plate manufacturing waste liquid.

1, 1’, 1”: Polarizer manufacturing waste liquid treatment device

10: The first processing device

11: Evaporation and concentration device

12: Cooling crystallization device

13: The first solid-liquid separation device

20: The second processing device

21: Evaporation crystallization device

22: The second solid-liquid separation device

23: Dissolving tank

30: The first impurity adsorption device

40: The second impurity adsorption device

50: 1st filter device (1st filter)

52: The second filter device

54: The third filter device

120: The second processing device

121: The first reaction device

122: The second reaction device

Fig. 1 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to an embodiment of the present invention.

Fig. 2 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to another embodiment of the present invention.

Fig. 3 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to another embodiment of the present invention.

form for carrying out the invention

One embodiment of the present invention will be described below with reference to the attached drawings. Fig. 1 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to an embodiment of the present invention. As shown in FIG. 1 , the processing device 1 for polarizing plate manufacturing waste liquid includes a first processing device 10 , a first impurity adsorption device 30 , and a second impurity adsorption device 40 , and also includes a first filter device 50 and a second filter device 52 . And the 3rd filtering device 54. The processing device 1 for waste liquid from the production of polarizing plates is used to treat the waste liquid from the production of polarizing plates generated in the production steps of polarizing plates used in liquid crystal displays and the like. In the manufacturing process of polarizing plates, generally, a film made of polyvinyl alcohol (PVA) is immersed in potassium iodide (KI) solution, stretched in boric acid (H ₃ BO ₃ ) aqueous solution, washed with water and dried. out of the polarizer. Therefore, the polarizing plate manufacturing waste liquid contains PVA, and also contains mainly KI and boric acid in an ion state.

The first treatment device 10 is equipped with an evaporation concentration device 11, a cooling crystallization device 12, and a first solid-liquid separation device 13, and generates boron-containing And PVA impurity reduced KI solution.

The evaporating and concentrating device 11 is for evaporating and concentrating the polarizing plate manufacturing waste liquid. Thereby, most of the boric acid and PVA contained in the polarizing plate manufacturing waste liquid can be supersaturated to become sludge, and the precipitates including these are generated in the polarizing plate manufacturing waste liquid. The precipitate may also contain impurities other than boric acid and PVA. The configuration of the evaporative concentration device 11 is not particularly limited as long as it can concentrate the waste liquid from the manufacture of polarizers. For example, known evaporative concentration devices such as heat pump type, ejector-driven type, steam type, and flash type can be used. One or more of these can be used. Composed of two or more. For example, the evaporation and concentration device 11 can be configured in the following manner: a heat pump type concentration device is arranged in the front stage, and a flash type concentration device is arranged in the rear stage to further evaporate the concentrated liquid of the polarizing plate production waste liquid generated in the heat pump type concentration device. concentrate.

Cooling and crystallization device 12 is made by polarizing plate manufacturing waste liquid Crystallization of the boric acid contained in the polarizer to further generate precipitates from the waste liquid of polarizer manufacturing. The structure of the cooling crystallization device 12 can be known such as jacket type and vacuum type, and it is preferable to cool the polarizing plate manufacturing waste liquid to below 45°C (for example, 40~45°C), and cool it to normal temperature (a specific example is below 30°C) is better. The crystallization method of polarizer manufacturing waste liquid is preferably cooling crystallization using the cooling crystallization device 12 as in this embodiment in order to obtain a good effect of reducing impurities such as boric acid, but it can also be other crystallization operations. .

The first solid-liquid separation device 13 is for solid-liquid separation of precipitates in the polarizing plate manufacturing waste liquid. The configuration of the first solid-liquid separation device 13 can be, for example, various filtration devices such as pressure filtration (press filtration), vacuum filtration, or centrifugal filtration, or a known configuration such as a decanter-type centrifugal separation device.

The first impurity adsorbing device 30 has a polyvinyl alcohol adsorbing body (PVA adsorbing body), and circulates the KI solution supplied from the first processing device 10 through the PVA adsorbing body, thereby adsorbing and removing a small amount of PVA remaining in the KI solution. The PVA adsorbent is not particularly limited as long as it is a solid substance capable of adsorbing PVA on its surface. Preferred examples include granular or fibrous activated carbon filters, but titanium oxide and the like can also be used.

The second impurity adsorption device 40 is equipped with an adsorption tower filled with a resin that selectively adsorbs boron, and the KI solution that has passed through the first impurity adsorption device 30 is circulated in the adsorption tower, thereby adsorbing and removing the remaining boric acid in the KI solution. some boron. The resin for selectively adsorbing boron is not particularly limited as long as it is capable of selectively adsorbing boron, and known anion exchange resins (such as cerium hydroxide/ethylene vinyl alcohol copolymer, microporous styrene, methyl-reduced glucose, etc.) can be used. amine functional groups, etc.).

The first filtering device 50, the second filtering device 52, and the third filtering device 54 are all equipped with filters such as ceramic membrane filters or filter cartridges, and are respectively arranged between the first processing device 10 and the first impurity adsorption device 30. Between the impurity adsorption device 30 and the second impurity adsorption device 40 , and the stage after the second impurity adsorption device 40 . The first filtering device 50 removes impurities by filtering the KI solution supplied from the first processing device 10 . The second filtering device 52 removes SS components (suspended solids) (such as activated carbon chips, etc.) that may be mixed into the KI solution by filtering the KI solution that has passed through the first impurity adsorption device 30 . The third filtering device 54 removes SS components that may be mixed into the KI solution (such as resin chips that selectively adsorb boron, etc.) by filtering the KI solution that has passed through the second impurity adsorption device 40 .

Next, the processing method of the polarizing plate manufacturing waste liquid using the above-mentioned polarizing plate manufacturing waste liquid processing apparatus 1 is demonstrated.

First, the polarizing plate manufacturing waste liquid is supplied to the first processing device 10 . The pH of polarizing plate manufacturing waste is in the range of 3.5 to 8.0. It is generally acidic because it contains boric acid solution, but polarizing plate manufacturing waste near neutral can also be used. Alternatively, the pH of the polarizing plate manufacturing waste can be adjusted to be alkaline (for example, 8.5-11, preferably 8.5-9.5) by adding a pH regulator such as sodium hydroxide or potassium hydroxide to the polarizing plate manufacturing waste.

In the first treatment device 10 , the polarizer manufacturing waste liquid is concentrated by the evaporative concentration device 11 , and then cooled by the cooling crystallization device 12 to perform cooling crystallization. If the pH of the polarizing plate production waste liquid concentrated by the evaporator 11 is to be adjusted to be alkaline, it is preferable to maintain the pH of the concentrated waste liquid at alkaline for cooling and crystallization. Afterwards, the precipitate was passed through the first Solid-liquid separation device 13 and removed. As described above, the first treatment step is performed using the first treatment device 10 to produce a KI solution in which impurities including boron and PVA are reduced.

The precipitate separated by the first treatment step is a crystal mainly composed of boric acid and contains PVA. The main boric acid crystals can be washed and recovered by using, for example, condensed water generated in the evaporating and concentrating device 11 , so that they can be reused in, for example, manufacturing steps of semiconductors and LEDs. Since the precipitate contains some KI crystals in addition to boric acid and PVA, the washed waste liquid can also be introduced into the evaporative crystallization device 21 (see FIG. 2 ) in other embodiments described later. The crystallization in the first treatment step can be repeated until KI crystallizes out, and the impurity precipitate can be removed by solid-liquid separation.

In the first impurity adsorption device 30, the first impurity adsorption step is carried out. In this step, a little PVA remaining in the KI solution obtained in the first treatment step is adsorbed and removed by the PVA adsorbent. Afterwards, in the second impurity adsorption device 40, the second impurity adsorption step is carried out. In this step, some boron remaining in the KI solution after the first impurity adsorption step is adsorbed and removed by a boron-selective resin. As mentioned above, some PVA and boron contained in the KI solution will be removed by the first impurity adsorption step and the second impurity adsorption step respectively, so high-quality potassium iodide solution can be recovered from the polarizer manufacturing waste liquid.

According to the high concentration test of the KI solution done by the inventors, it is obvious that when the concentration of the KI solution is a saturation concentration or a concentration close to the saturation concentration (for example, about 55%), the PVA contained in the KI solution will hinder the selectivity The boron-adsorbing resin can only adsorb boron, so it cannot fully adsorb boron. therefore, In this embodiment, after the PVA in the KI solution is removed by the first impurity adsorption step, the boron in the KI solution is removed by the second impurity adsorption step, whereby even the high-concentration KI solution as described above, Boron can still be reliably removed.

To pass the KI solution through the first impurity adsorption device 30 and the second impurity adsorption device 40, since boron and PVA have been sufficiently reduced by the first treatment device 10, the regeneration of the resin or PVA adsorbent that selectively adsorbs boron can be greatly reduced load, and can efficiently recover high-quality potassium iodide solution.

One embodiment of the present invention has been described in detail above, but the first treatment device 10 cannot sufficiently reduce the impurities including boron and PVA due to reasons such as the large amount of impurities contained in the original polarizing plate manufacturing waste liquid. When, the 2nd processing device can also be set in the rear stage of the 1st processing device 10, and carry out the 2nd processing step between the 1st processing step and the 1st impurity adsorption step to further reduce the impurity of potassium iodide solution. The structure of the 2nd processing apparatus is not specifically limited, Preferably, the structure shown in FIG. 2 and FIG. 3 can be illustrated. In FIGS. 2 and 3 , the same components as those in FIG. 1 are given the same symbols.

Fig. 2 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to another embodiment of the present invention. The processing device 1' of polarizing plate manufacturing waste liquid shown in FIG. 2 is to arrange the second processing device 20 between the first processing device 10 and the first filter 50 in the processing device 1 of polarizing plate manufacturing waste liquid shown in FIG. Or, the configuration other than the second processing device 20 is the same as that of the processing device 1 for polarizing plate manufacturing waste liquid shown in FIG. 1 .

The 2nd treatment device 20 is equipped with evaporation crystallization device 21, the 2nd Solid-liquid separation device 22 and dissolution tank 23. The configurations of the evaporative crystallization device 21 and the second solid-liquid separation device 22 are not particularly limited. For example, they can have the same configuration as the evaporation concentration device 11 and the first solid-liquid separation device 13 of the first processing device 10, respectively. In this embodiment, a flash type evaporator is used as the evaporation crystallization device 21 .

The evaporative crystallization device 21 evaporates the KI solution concentrated in the first processing device 10 to supersaturate KI, thereby generating a precipitate containing KI crystals. The pH can also be adjusted by adding KOH to the KI solution as the evaporation and crystallization proceed. The second solid-liquid separation device 22 separates and recovers the precipitate generated in the evaporative crystallization device 21 from solid to liquid.

Through the first treatment step, the concentration of boric acid and PVA contained in the KI solution is reduced, so the precipitate generated by the evaporative crystallization device 21 is a crystal mainly composed of KI. However, if the concentration ratio is increased in order to increase the yield of KI, the amount of PVA that is likely to cause problems during recovery will also increase. Therefore, by washing the KI crystals in the second solid-liquid separator 22 , impurities adhering to the KI crystals are removed.

For example, the condensed water generated in the evaporative concentration device 11 can be used as a cleaning solution for cleaning KI crystals. However, since KI has a high solubility, the loss caused by dissolution will be large. Therefore, in order to reduce the loss caused by dissolution, it is advisable to use a part of the recovered KI to generate a KI saturated solution, and use the KI saturated solution to wash the KI crystals. The concentration of the KI saturated solution does not have to be the saturation concentration, as long as it is a high concentration close to the saturation concentration. By washing with a high-concentration KI solution, PVA can be efficiently removed, and PVA can be mixed into less KI crystals by using a filter, etc. To be solid-liquid separation and recovery. The cleaning solution can be stored in the tank for recycling.

The recovered KI crystals are dissolved in a solvent such as water in the dissolving tank 23 to generate a KI solution with reduced impurities. In the case of using water as a solvent, dissolving KI crystals in water is an endothermic reaction. For example, if KI crystals are dissolved in water at 20°C to make it a 55% solution, the temperature of the KI solution will be about -5°C . Since the recovered KI crystals are mixed with impurities such as boron and PVA, the saturation solubility of the impurities (mainly PVA) can be reduced by lowering the temperature of the solvent that has dissolved the KI crystals at a high concentration, and some or most of the impurities will be released. Precipitate. The precipitate is filtered by the first filter device 50 .

According to the above, by cleaning the recovered KI crystals, the impurities mainly attached to the surface of KI crystals can be reduced, and at the same time, the endothermic reaction when the KI crystals are dissolved can be used to precipitate and remove the PVA contained in the KI crystals. A fully reduced PVA KI solution was generated. Therefore, the load on the PVA adsorbent included in the first impurity adsorption device 30 can be reduced.

Fig. 3 is a block diagram of a treatment device for waste liquid from the manufacture of polarizing plates according to another embodiment of the present invention. The processing device 1" of the waste liquid from the manufacture of the polarizing plate shown in FIG. The configuration other than the second processing device 120 is the same as that of the processing device 1 for polarizing plate manufacturing waste liquid shown in FIG. 1 .

The 2nd treatment device 120 shown in Figure 3 has the 1st reaction device 121 and the 2nd reaction device 122, and the 1st reaction device 121 is to the KI solution that impurity is reduced through the 1st treatment device 10 and supplies calcium ion and generates precipitate and removes. In order to remove the precipitate, the second reaction device 122 supplies carbonate ions to the KI solution passed through the first reaction device 121 to generate a precipitate and remove the precipitate.

The first reaction device 121 is to add calcium hydroxide to make some remaining boron in the KI solution react with calcium ions to form a calcium borate precipitate, and remove the precipitate with a filter, thereby further reducing the amount contained in the KI solution. of boron. Since the KI solution supplied to the first reaction device 121 is concentrated through the first treatment step, distilled water or the like may be added before supplying calcium hydroxide to dilute the concentration of the KI solution to an appropriate concentration (for example, 15-30%).

The second reaction device 122 supplies carbonate ions to the KI solution that has passed through the first reaction device 121 . In this way, the calcium ions remaining in the KI solution will react with the carbonate ions to form calcium carbonate precipitates, and the precipitates can be removed with a filter to remove the calcium ions from the KI solution. The supply of carbonate ions will suppress the increase of impurities in the KI solution, so it should be done by adding potassium carbonate or carbon dioxide. Using the second treatment device 120 to perform the second treatment step as described above can further reduce impurities in the KI solution.

In the configuration of Fig. 1 to Fig. 3, the concentration of boron and PVA in the KI solution introduced into the first impurity adsorption device 30 is not particularly limited, but if it is too high, the exchange or regeneration of the resin and PVA adsorbent that selectively adsorb boron The frequency of will become high, and it will become difficult to use in practical applications. Specifically, the boron concentration should be 100-1000 mg/L, and the polyvinyl alcohol concentration should be 100-500 mg/L in TOC conversion. The boron concentration and PVA concentration of the KI solution can be finally reduced to several mg/L by the subsequent first impurity adsorption step and second impurity adsorption step.

1‧‧‧Polarizer manufacturing waste liquid treatment device

10‧‧‧First processing device

11‧‧‧Evaporation and concentration device

12‧‧‧Cooling crystallization device

13‧‧‧The first solid-liquid separation device

30‧‧‧The first impurity adsorption device

40‧‧‧The second impurity adsorption device

50‧‧‧1st filter device (1st filter)

52‧‧‧The second filter device

54‧‧‧The third filter device

Claims (9)

A method for treating polarizer manufacturing waste liquid, which is to recover potassium iodide from the polarizer manufacturing waste liquid, and the processing method has the following steps: the first treatment step is to carry out crystallization after the polarizer manufacturing waste liquid is concentrated to form precipitates and make the precipitate solid-liquid separation to generate a potassium iodide solution containing boron and polyvinyl alcohol with reduced impurities; the first impurity adsorption step is to make the polyvinyl alcohol adsorbent absorb the potassium iodide solution obtained in the first treatment step above Residual polyvinyl alcohol; and the second impurity adsorption step is to make the resin adsorbing selective adsorption of boron absorb and remove the remaining boron in the potassium iodide solution of polyvinyl alcohol by the aforementioned first impurity adsorption step. The processing method of polarizing plate manufacturing waste liquid as claimed in item 1, which is equipped with a second processing step between the aforementioned first processing step and the aforementioned first impurity adsorption step, and the second processing step is to further reduce the aforementioned first processing step The aforementioned impurities in the potassium iodide solution obtained in The processing method of polarizing plate manufacturing waste liquid as claimed in claim 2, wherein the second processing step has the following steps: further concentrating the potassium iodide solution obtained in the first processing step to precipitate potassium iodide crystals; making the precipitated potassium iodide A step of solid-liquid separation of crystallization; a step of washing the potassium iodide crystals that have undergone solid-liquid separation to recover the potassium iodide crystals from which impurities have been removed; and a step of dissolving the recovered potassium iodide crystals into a solvent to generate a potassium iodide solution. As in claim 3, the method for treating waste liquid from the manufacture of polarizing plates further includes the step of filtering impurities, which are precipitated due to the decrease in saturated solubility caused by the endothermic reaction when potassium iodide crystals are dissolved. The method for treating waste liquid from the manufacture of polarizing plates according to claim 2, wherein the second treatment step includes a step of removing calcium borate precipitates, which are produced by reacting boron contained in potassium iodide solution with calcium ions . The processing method of polarizing plate manufacturing waste liquid as claimed in item 5, wherein the aforementioned second processing step is further equipped with the step of removing calcium carbonate precipitates, which are formed by reacting calcium ions remaining in the potassium iodide solution with carbonate ions generator. A method for treating waste liquid from the manufacture of polarizing plates according to any one of claims 1 to 6, wherein in the potassium iodide solution for the aforementioned first impurity adsorption step, the concentration of boron is 100-1000 mg/L, and the concentration of polyvinyl alcohol is converted to TOC. 100~500mg/L. A processing device for polarizing plate manufacturing waste liquid, which recovers potassium iodide from polarizing plate manufacturing waste liquid, and the processing device is provided with the following devices: a first processing device is used for crystallization after concentrating the polarizing plate manufacturing waste liquid to form precipitates and make the precipitate solid-liquid separation to generate a potassium iodide solution containing boron and polyvinyl alcohol with reduced impurities; the first impurity adsorption device is to make the polyvinyl alcohol adsorbent absorb in the potassium iodide solution obtained by the first treatment device Residual polyvinyl alcohol; and the second impurity adsorption device, which is to adsorb and remove the iodide of polyvinyl alcohol that has been adsorbed by the aforementioned first impurity adsorption device to the resin that selectively adsorbs boron Residual boron in potassium solution. According to claim 8, the processing device for polarizing plate manufacturing waste liquid is equipped with a second processing device, and the second processing device further reduces the aforementioned impurities in the potassium iodide solution obtained in the aforementioned first processing device.

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