KR20110135856A - Method for classifying powder - Google Patents

Abstract

In the method for classifying powders using a fluid classifier, a mixing step (step S10) of mixing a powder composed of nickel with an organic solvent having a flash point of 80 ° C. or higher, and the powder mixed in the mixing step An injecting step (step S22) to be introduced into the fluid classifier, a heating step (step S14) to heat the gas, and a supply step of supplying the gas heated in the heating step to the fluid classifier (step) (S16)] and a classification step (step S24) for classifying the powder based on the particle size in the fluid classifier.

Description

Classification method of powder {METHOD FOR CLASSIFYING POWDER}

TECHNICAL FIELD This invention relates to the classification method of the powder which classifies powder which has a particle size distribution effectively in a desired classification point (particle size).

When classifying powder, such as glass blast furnace slag, into fine powder and coarse powder, the classification method which adds the preparation of fluids, such as alcohol, is known (for example, refer patent document 1). In this classification method, a preparation containing polar molecules is added to the powder to electrically neutralize the polarity of the powder particles, thereby preventing the particles from adsorbing and agglomerating to form agglomerated particles having a large particle size, thereby lowering the classification efficiency. Is preventing.

Japanese Patent Laid-Open No. 1989-85149

However, today, as an internal electrode of a multilayer ceramic capacitor, extremely small fine powder of nickel with an average particle diameter of 1 micrometer or less is used, for example. In order to obtain a high quality multilayer ceramic capacitor, not only the average particle diameter is extremely small, but also the width of the particle size distribution is extremely narrow, that is, a more homogeneous fine powder is required. However, in the conventional classification method by centrifugation, since the powder of raw material adheres to each part in a classifier, and the inlet of a raw material or the blower outlet of high pressure gas is closed, it has become difficult to operate for a long time, deteriorating classification performance. .

An object of the present invention is to provide a powder classification method capable of performing the classification of powder with high accuracy.

The classification method of the powder of this invention is a classification method of the powder using a fluid classifier, Comprising: The mixing process of mixing the powder which consists of nickel, and the preparation which consists of an organic solvent with a flash point of 80 degreeC or more, In the said mixing process, In the input step of injecting the mixed powder into the fluid classifier, the heating step of heating the gas, the supply step of supplying the gas heated in the heating step to the fluid classifier, and in the fluid classifier It is characterized by including the classification process which classifies powder based on particle size.

Moreover, the classification method of the powder of this invention is a classification method of the powder using a fluid classifier, The mixing process which mixes the powder which consists of nickel, and the preparation which consists of water, and the said powder mixed in the said mixing process to the said fluid classifier A feeding step of feeding, a heating step of heating a gas, a supplying step of supplying the gas heated in the heating step to the fluid classifier, and a classification to classify the powder based on a particle size in the fluid classifier. It characterized by including a process.

According to the classification method of the powder of this invention, it is possible to classify powder with high precision using water or an organic solvent with a high flash point as a preparation.

1 is a schematic configuration diagram showing a configuration of a classification apparatus according to a first embodiment;
2 is a longitudinal sectional view showing a configuration of an interior of a classifier according to the first embodiment;
3 is a cross sectional view showing a configuration of an interior of a classifier according to the first embodiment;
4 is a flowchart for explaining a classification method of powder according to the first embodiment;
5 is a flowchart for explaining a classification method of powder according to a second embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the classification method of powder which concerns on 1st Embodiment of this invention is demonstrated with reference to drawings. 1 is a schematic block diagram showing a configuration of a fluid classifier used by the method for classifying powder according to the present embodiment.

As shown in FIG. 1, the classification apparatus 2 inject | pours powder into the classifier (fluid classifier) 4 and the classifier 4 which classify the powder thrown in as a raw material by the swirling airflow generated inside. The feeder 6, the blower 8 which supplies a high pressure gas to the classifier 4, and the 1st heater 10 which heats the supplied high pressure gas to predetermined temperature is provided. In addition, the classifier 2 is sucked by the suction blower 12 which sucks and collect | recovers the fine powder isolate | separated to below the desired classification point with the gas in the classifier 4, and the negative pressure which generate | occur | produces in the classifier 4. It has the 2nd heater 14 which heats | atmosphere (atmospheric gas), and the collection | recovery container 16 which collect | recovers coarse powder with a large centrifuged particle diameter.

A classifier 4 having a substantially conical shape is provided with the vertex of the cone facing downward, and a centrifuge chamber 20 (see FIG. 2), which will be described later in detail, is formed in the upper portion of the classifier 4. have. In the centrifugal separation chamber 20, the atmosphere as the atmospheric pressure gas existing outside the classifier 4 and the high pressure gas from the blower 8 are supplied, and the powder as the classification target is fed from the feeder 6. .

The feeder 6 has a screw (not shown) inside, and by rotating the screw, it is possible to quantitatively deliver the powder contained therein. The conveyed powder is introduced into the classifier 4 from the inlet port 26 (see FIG. 2) provided on the surface of the classifier 4. In addition, the powder accommodated in the feeder 6 is previously mixed with the preparation mentioned later in detail.

The blower 8 compresses the atmosphere to generate a high pressure gas and supplies it to the classifier 4 via the first heater 10. The 1st heater 10 has the piping which a high pressure gas passes inside, and the heating means which consists of a filament, an aerofin, etc. is provided in this piping. The heating means heats the high pressure gas passing through the pipe to a predetermined temperature and removes moisture contained in the high pressure gas. In addition, another dewatering means for removing the water containing the high pressure gas may be separately provided between the blower 8 and the classifier 4, or a filter for removing dust or the like may be appropriately provided.

The suction blower 12 together with the gas which exists in the classifier 4 from the inlet 32 (refer FIG. 2) provided in the center of the upper surface of the classifier 4 by the fine powder isolate | separated by the classifier 4 is made. Recover by inhalation. In addition, a filter such as a bug filter may be appropriately provided between the suction port 32 and the suction blower 12. Here, when the suction blower 12 inhales a gas, since a negative pressure will generate | occur | produce in the classifier 4, the atmosphere which is the atmospheric pressure gas which exists outside the classifier 4 will be inhaled in the classifier 4. In this way, the atmospheric gas is sucked in, so that the swirling airflow for high-speed swing is formed in the centrifugal chamber 20 of the classifier 4. Moreover, since the classification apparatus 2 which concerns on this embodiment is equipped with the 2nd heater 14 which heats the normal-pressure gas suctioned, it can heat the temperature of the turning airflow in the centrifugation chamber 20 to predetermined temperature. Can be. Similar to the first heater 10, the second heater 14 has a pipe through which the atmospheric gas passes, and heating means such as filament and aerofin are provided inside the pipe.

The recovery container 16 is provided in the lowermost part of the classifier 4, and collects the coarse powder which descended along the inclined surface of the conical part of the classifier 4 after centrifuging in the centrifugation chamber 20. As shown in FIG.

Next, the classifier 4 which concerns on this embodiment is demonstrated with reference to FIG. 2 and FIG. 2 is a longitudinal cross-sectional view by the surface containing the central axis of the classifier 4, and FIG. 3 is a cross-sectional view in the position of the centrifugal separation chamber 20 by the plane perpendicular | vertical to the said central axis. In addition, in order to clarify the relative positional relationship with other components (especially the jet nozzle 30 and guide vane 40 mentioned later), the inlet 26 and jet nozzle which are not shown originally in FIG. 30 is shown by the virtual line and the dotted line, respectively. In addition, only two ejection nozzles 30 are shown in order to demonstrate.

As shown in FIG. 2, the upper disc member 22 having a flat disc shape and the lower disc member 24 having a hollow disc shape are provided at a predetermined interval in the upper part of the classifier 4. It is hold | maintained and arrange | positioned, The cylindrical centrifugal separation chamber 20 is formed between both disk shaped members. Above the centrifugal separation chamber 20, an injection port 26 through which the powder introduced from the feeder 6 described above passes is formed. As shown in FIG. 3, a plurality of guide vanes 40 are arranged at equal intervals on the outer periphery of the centrifugal separation chamber 20, and below the centrifugal separation chamber 20, the lower disc shaped member ( After being centrifuged along the outer circumferential wall of 24), a reclassification zone 28 is formed for returning the powder dropped from the centrifuge chamber 20 back into the centrifuge chamber 20.

Near the upper end of the outer circumferential wall of the reclassification zone 28, the ejection nozzle 30 for ejecting the high pressure gas supplied from the above blower 8 is arranged so that the ejection direction is substantially the same as the tangential direction of the outer circumferential wall. It is. The jet nozzle 30 blows out the high pressure gas to disperse the powder introduced from the inlet 26, and supplies the gas auxiliaryly to the centrifugal chamber 20. In addition, the fine powder present in the reclassification zone 28 is returned into the centrifuge chamber 20. In addition, although the six jet nozzles 30 are arrange | positioned on the outer peripheral wall of the reclassification zone 28 in this embodiment, this is an example, and there exists a freedom in the arrangement position and the number of jet nozzles 30. FIG.

In the center of the upper part of the centrifugal chamber 20, the suction port 32 which suction-recovers coarse powder and the separated fine powder by centrifugation is provided. Further, the coarse powder centrifuged is dropped from the reclassification zone 28 from the inclined surface of the conical part of the classifier 4 and discharged from the discharge port 34 provided at the lowermost part of the classifier 4, and the above-described recovery container ( 16) is accommodated.

As illustrated in FIG. 3, a guide vane 40 is formed at the outer circumferential portion of the centrifugal separation chamber 20 to form a turning airflow in the centrifugal separation chamber 20 and to adjust a turning speed of the turning airflow. have. In addition, in this embodiment, 16 guide vanes 40 are arrange | positioned as an example. The guide vane 40 is rotatably supported between the upper disk-shaped member 22 and the lower disk-shaped member 24 by the rotation shaft 40a, and is not shown by the pin 40b. It is fixed with respect to a copper plate (rotating means), and it is comprised so that all guide vanes 40 may be rotated at predetermined angle simultaneously by rotating this rotating plate. In this way, the guide vanes 40 are rotated by a predetermined angle to adjust the interval of each guide vane 40, thereby changing the flow velocity of the atmospheric gas passing through the interval in the direction of the white arrow shown in FIG. The flow velocity of the swirling airflow in the centrifugal chamber 20 can be changed. By changing the flow velocity of the swirling airflow in this way, the classification performance (specifically, the classification point) of the classifier 4 which concerns on this embodiment can be changed. In addition, as above-mentioned, the atmospheric pressure gas which passes the space | interval of each guide vane 40 is the atmospheric pressure gas heated beforehand by the 2nd heater 14 to predetermined temperature.

Next, the classifying method of powder which concerns on this embodiment is demonstrated using the flowchart of FIG. First, mixing of the powder to be classified and the preparation to be liquid is carried out (step S10). Here, the type of preparation to be used may be appropriately selected according to the type of powder to be classified, but, as in the method for classifying powder according to the present embodiment, when the classification object is a powder of nickel, it is used as an example of water or glee as a preparation. It is preferable to use an organic solvent having a flash point of 80 ° C. or higher, such as diethylene glycol (flash point 124 ° C.). In addition, about the addition amount of a preparation and the mixing method, what is necessary is just to select suitably according to the kind of powder, but in the classification method of the powder which concerns on this embodiment, after adding a preparation of a predetermined ratio with respect to the powder used for classification, it uses a mixer. Mixing. In addition, since a part of the preparation added to the powder is evaporated during and after mixing with the powder, the amount of the preparation contained in the mixed powder when the mixed powder is fed into the feeder 6 of the classification apparatus 2 starts mixing. It decreases rather than the amount of preparation added at the time.

In addition, Hi-X (made by Nisshin Engineering Co., Ltd.) is used for the mixer.

When the classification apparatus 2 is operated, suction of gas is started by the suction blower 12 (step S12). Since the gas in the centrifugal chamber 20 is sucked in from the suction port 32 provided in the upper center of the centrifugal chamber 20, the air pressure in the central portion of the centrifugal chamber 20 is relatively low. As a result, the negative pressure generated in the centrifugal chamber 20 sucks the atmospheric air, which is an atmospheric pressure gas, between the guide vanes 40 arranged along the outer circumference of the centrifugal chamber 20, and enters the centrifugal chamber 20. It is supplied (step S16). In addition, the atmospheric pressure gas sucked into the centrifugal separation chamber 20 is previously heated to a predetermined temperature by passing through the pipe provided in the second heater 14 (step S14). In this way, the atmospheric pressure gas is sucked from between the guide vanes 40, so that a swirling airflow having a flow rate determined according to the rotation angle of the guide vanes 40 is formed. Moreover, in the classification method of the powder which concerns on this embodiment, the atmospheric pressure gas sucked is heated so that the temperature of the swirling airflow in the centrifugal separation chamber 20 may be about 110 degreeC.

Next, the blower 8 is used to start the supply of the high pressure gas toward the centrifuge chamber 20 of the classifier 4. The high pressure gas injected from the blower 8 is heated by the first heater 10 to a predetermined temperature (step S18). In addition, similarly to the second heater 14, the first heater 10 heats the high-pressure gas so that the temperature of the swirling air flow in the centrifugal separation chamber 20 is about 110 ° C. The high pressure gas heated up to a predetermined temperature is blown out from the plurality of jet nozzles 30 provided on the outer circumferential wall of the centrifugal separation chamber 20 and supplied into the centrifugal separation chamber 20 (step S20).

As described above, when a state in which the high-speed swirling air heated to about 110 ° C. normally turns inside the centrifugal chamber 20 is formed, the mixed powder quantitatively sent out from the feeder 6 is centrifuged from the inlet 26. It is thrown into the chamber 20 (step S22). As shown in FIG. 2, since the inlet 26 is provided above the outer peripheral part of the centrifuge chamber 20, the mixed powder thrown in from the inlet 26 turns around the outer peripheral part of the centrifuge chamber 20 at high speed. The collision with the swirling air flow disperses rapidly. At this time, the dispersion of the powder is promoted by rapidly evaporating the preparations mixed between the fine particles of the powder. In this way, the powder dispersed in the unit of fine particles is in the centrifugal chamber 20 without being attached to the surface of the upper disk member 22, the lower disk member 24, or the like constituting the centrifugal chamber 20. Is rotated several times, and classified based on the particle size of the powder (step S24).

As a result of the centrifugal separation action in the centrifugal chamber 20, the fine powder having a particle size smaller than the desired classification point is concentrated in the center of the centrifugal chamber 20, and the upper disk member 22 and the lower disk member are concentrated. By the effect of the ring-shaped convex portions provided in the central portions of the 24, the gas is recovered from the intake port 32 together with the gas sucked by the intake blower 12 (step S26). Further, after the coarse powder having a particle size exceeding the classification point is concentrated on the outer peripheral part of the centrifugal separation chamber 20 by the centrifugal action in the centrifugal separation chamber 20, the classifier (from the reclassification zone 28) The conical part of 4) is dropped, discharged from the discharge port 34, and accommodated in the recovery container 16.

As described above, the powder dispersed effectively by the high-temperature swirling air flow and the effect of preparation that rotates inside the centrifugal separation chamber 20 is centrifuged without being attached to the upper surface of the components constituting the centrifugal separation chamber 20 or the like. The inside of the room 20 is turned and efficiently classified into the fine powder below the desired classification point and the remaining coarse powder. In addition, since the added preparation vaporizes all, it is not contained in collect | recovered powder.

In addition, in this embodiment, although the gas supplied is heated so that the swirling airflow in the classifier 4 may be about 110 degreeC, the temperature of the swirling airflow in the classifier 4 is not limited to about 110 degreeC, but is centrifugal. The temperature at which the preparation is vaporized in the separation chamber 20 may be sufficient.

In addition, in this embodiment, although demonstrated using water or glycols for preparation, you may use ketones as preparation.

Next, with reference to drawings, the classification method of powder which concerns on 2nd Embodiment of this invention is demonstrated. In addition, the structure of the classification method of the powder which concerns on this 2nd Embodiment is changed so that the mixing process of the classification method of the powder which concerns on 1st Embodiment may be mixed, heating. Therefore, the detailed description of the same structure as the above-mentioned classification apparatus 2 is abbreviate | omitted, and only another part is demonstrated in detail. In addition, the same code | symbol is attached | subjected and demonstrated to the structure similar to the structure of the classification apparatus 2 mentioned above.

5 is a flowchart for explaining a method for classifying powder according to the second embodiment. First, the powder and the preparation to be classified are mixed while heating (step S30). Here, the type of preparation to be used may be appropriately selected according to the type of powder to be classified, but, as in the method for classifying powder according to the present embodiment, when the classifying object is nickel powder, it is water or glycol as a preparation. It is preferable to use the organic solvent of 80 degreeC or more of flash points, such as ethylene glycol (flash point 124 degreeC). At this time, in this embodiment, it heats about 75 degreeC, but what is necessary is just to select a heating temperature suitably by the combination of powder and a preparation. Next, although the processes shown in steps S32 to S40 are executed, these processes are the same as those shown in steps S12 to S20 in the flowchart of FIG. 4, and thus description thereof is omitted. Then, the mixed powder quantitatively sent out from the feeder 6 is introduced into the centrifugal chamber 20 from the inlet 26 (step S42). At this time, since it is heated in step S30, the mixed powder is thrown into the centrifuge chamber 20 at a predetermined temperature. Although the processing shown in steps S44 and S46 is executed, these processings are the same as the processing shown in the steps S24 and S26 of the flowchart of FIG.

In addition, regarding the temperature setting of the turning airflow in the centrifuge 20, the 2nd heater 14 heats the normal-pressure gas sucked so that the temperature of the turning airflow may be about 110 degreeC in step S34. And also in step S40, the high pressure gas is heated by the 1st heater 10 so that the temperature of swirling airflow may be about 110 degreeC.

[Example]

Next, the classification method of the powder according to the present embodiment will be described in more detail using examples. In this embodiment, 0.5 m <3> / min of the amount of gas to be inhaled by the suction blower 12 shown in FIG. 1 using the classifier equipped with heat insulation equipment, and the pressure of the high pressure gas which the blower 8 produces | generates are 0.5. It is set as MPa. In addition, in the present Example, as powder to classify, the powder which consists of fine powders of nickel (median diameter 0.73 micrometer, the ratio of 7 micrometers of 1 micrometer or less, the maximum particle diameter of 3.3 micrometers), and fine powder of nickel is used as a preparation in water or An organic solvent is added and the mixed powder is used. In addition, the input of powder to the classifier was set to 500 g / hour. In addition, the temperature in a classifier is set to 110 degreeC. In addition, the temperature in a classifier is calculated | required by measuring the temperature of the gas immediately after inhaling from the suction port in a classifier by the suction blower of a classifier. In addition, the preparation added to the powder as described above partially evaporates during and after mixing with the powder. Therefore, in this embodiment, when adding mixed powder to the feeder 6 of the classification apparatus 2, the quantity of the preparation added when mixing with powder is referred to as "the amount of the preparation contained in mixed powder" Adsorption amount ”.

(Example 1)

In Example 1, water was used as a preparation, and water was added 3 to 5% by mass ratio with respect to nickel powder. In addition, mixing of nickel powder and water was performed at 20 degreeC and 75 degreeC. Table 2 shows the relationship between the addition amount (mass ratio) of water in the mixed powder, product yield, and product quality. In addition, the product quality is data for nickel recovered from the suction port 32 shown in step S26 of the flowchart of FIG. 4 and step S46 of the flowchart of FIG. 5. In addition, as a comparative example, experiments were also carried out for not performing the pretreatment for adding the preparation to the nickel powder.

Pretreatment Method Product yield
(Dry secretion)
[%] Product quality Type and amount of preparation Temperature at the time of mixing
(Powder temperature) [° C] pharmacy
Absorption amount
[%]
Less than 1㎛
ratio[%] Particle size
[Mu m] Example
1-1 Water (3%) 20 2.7 27.6 94.4 2.3 Example
1-2 Water (3%) 75 2.0 23.6 95.8 2.0 Example
1-3 Water (5%) 75 3.2 22.9 95.1 2.3 Comparative example
One No pretreatment 0 15.0 95.6 2.3 Comparative example
2 none 75 0 16.5 95.6 2.3

As shown in Table 1, when the classification of nickel powder was performed using water as a preparation, it turned out that product yield is high compared with the case of not adding preparation (Comparative Examples 1 and 2). Moreover, it turned out that when heating is performed at the time of mixing, product quality will also improve compared with Comparative Examples 1 and 2. In addition, although experiment was performed by adding water vapor into the centrifugal separation chamber 20 at the time of classification without performing pretreatment, the increase of product yield and the improvement of product quality were not seen.

Therefore, the product yield of nickel can be raised by using water as a preparation, and product quality can be improved further by mixing, mixing nickel powder and water, heating.

(Example 2)

In Example 2, 4% to 5% of diethylene glycol was added by mass ratio with respect to nickel powder, using diethylene glycol as an example of the organic solvent whose flash point is 80 degreeC or more as a preparation. In addition, mixing of nickel powder and diethylene glycol was performed at 20 degreeC and 75 degreeC. Table 2 shows the relationship between the addition amount (mass ratio) of diethylene glycol in the mixed powder, product yield, and product quality. In addition, the product quality is data regarding nickel recovered from the suction port 32 shown in step S26 of the flowchart of FIG. 4 and step S46 of the flowchart of FIG. 5. Moreover, the comparative example with respect to not performing pretreatment like Example 1 is also shown.

Pretreatment Method Product yield
(Dry secretion)
[%] Product quality Type and amount of preparation Temperature at the time of mixing
(Temperature of powder [° C] pharmacy
Absorption amount
[%]
Less than 1㎛
ratio[%] Particle size
[Mu m] Example
2-1 Diethylene glycol (4%) 20 3.7 29.9 93.2 2.3 Example
2-2 Diethylene glycol (5%) 75 4.1 25.8 97.8 1.6 Comparative example
One No pretreatment 0 15.0 95.1 2.3 Comparative example
2 none 75 0 16.5 95.6 2.3

As shown in Table 2, when the classification of nickel powder was performed using diethylene glycol (flash point 124 degreeC) as a preparation, it turned out that the product yield is high compared with the case where no preparation is added (Comparative Examples 1 and 2). . Moreover, it turned out that when heating is performed at the time of mixing, product quality will also improve compared with Comparative Examples 1 and 2.

Therefore, by using diethylene glycol as a preparation, the product yield of nickel can be improved, and product quality can be improved further by mixing, mixing a nickel powder and water.

When the fine powder of nickel, water, and diethylene glycol were mixed as a preparation from the result of Examples 1 and 2, it turned out that the product yield of nickel fine powder rises and classification efficiency increases. In addition, when the fine powder and the preparation of nickel are mixed while heating, the product quality is further improved. In addition, in any of the above-described Examples 1 and 2, centrifugation was continued for 30 minutes, but operation did not stop due to the blockage.

As described above, according to the method for classifying powders according to the above-described embodiments, after mixing the powder made of nickel, which is the object of classification, with the preparation made of organic solvent having water or flash point of 80 ° C or higher, the centrifugal separation chamber in the fluid classifier At the same time, a high-speed high-speed swirl airflow is formed in the centrifugal chamber by the heated gas, so that the classification of powder having a particle diameter of 1 m or less can be efficiently performed. In addition, when mixing the powder consisting of nickel, which is a classification target, with water or a flash point and a preparation composed of an organic solvent of 80 ° C. or higher, the viscosity of the preparation is lowered by heating, whereby the powder and the preparation are uniformly dispersed, and the product quality is improved. I improve it further.

2: classifier 4: classifier
6 feeder 8 blower
10: first heater 12: suction blower
14 second heater 20 centrifuge chamber
22: upper disk member 24: lower disk member
26: inlet 30: jet nozzle
32: inlet 40: guide vane

Claims (5)

In the classification method of powder using a fluid classifier,
A mixing step of mixing a powder made of nickel and a preparation made of an organic solvent having a flash point of 80 ° C. or higher,
An injecting step of injecting the powder mixed in the mixing step into the fluid classifier;
A heating step of heating the gas,
A supply step of supplying the gas heated in the heating step to the fluid classifier;
The fluid classifier includes a classification step of classifying the powder based on a particle size.
How to classify powder. The method of claim 1
The preparation is characterized in that the glycols
How to classify powder. The method of claim 1,
The preparation is characterized in that the ketones
How to classify powder. In the classification method of powder using a fluid classifier,
A mixing step of mixing a powder made of nickel and a preparation made of water,
An injecting step of injecting the powder mixed in the mixing step into the fluid classifier;
A heating step of heating the gas,
A supply step of supplying the gas heated in the heating step to the fluid classifier;
The fluid classifier includes a classification step of classifying the powder based on a particle size.
How to classify powder. The method according to any one of claims 1 to 4,
In the said mixing process, it mixes, heating the said powder which consists of said nickel, and the said preparation,
How to classify powder.

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