WO2012118221A1

WO2012118221A1 - Separation method and separation device for phosphor mixture

Info

Publication number: WO2012118221A1
Application number: PCT/JP2012/055530
Authority: WO
Inventors: 赤井　智子; 山下　勝; 達也大木
Original assignee: 独立行政法人産業技術総合研究所
Priority date: 2011-03-03
Filing date: 2012-03-05
Publication date: 2012-09-07
Also published as: JP5674142B2; JP2012184282A

Abstract

This separation method for a phosphor comprises: a step of bringing, into a treatment tube (100), a mixed solution (140) prepared by dispersing, into a dispersion medium, a mixture made of a plurality of types of phosphors of different magnetic susceptibilities, and of positioning, within the mixed solution, a filter (102) formed of a ferromagnetic material; a step of discharging and recovering the mixed solution from the treatment tube in a state where a magnetic field (130) has been applied to the filter; a step of cleaning the filter with dispersion medium and recovering the dispersion medium; and a step of cleaning the filter with dispersion medium in a state where the magnetic field has been reduced and recovering the dispersion medium. The dispersion medium is a solution in which a low-molecular-weight surfactant has been added to an aqueous solution of a high-molecular-weight dispersion agent. Each of the recovery steps is repeated using the recovered solution as a new mixture. Because a dispersion medium having high wettability is used on a fine-powder phosphor, the phosphor can be efficiently separated.

Description

Method and apparatus for separating phosphor mixture

The present invention is not limited to a case where a phosphor is efficiently separated from a mixture of a plurality of types of phosphor fine powders having different magnetic susceptibility using a magnetic separation technique based on a gradient magnetic field. The present invention also relates to a method for separating a phosphor mixture that includes purification to increase purity.

Fluorescent substances contain a large amount of rare earth elements, which are rare and valuable resources. For example, phosphors used in plasma displays and fluorescent lamps contain a large amount of expensive rare earth elements such as Tb and Eu. As shown in Table 1, various phosphors are used for displays or lamps.

Fluorescent lamp phosphors include BAM and SCA as blue phosphors, YOX and YVO as red phosphors, and LAP as green phosphors. As a phosphor that emits white light alone, there is a calcium halophosphate phosphor (hereinafter also referred to as a halophosphate daylight phosphor) (CoolWhite, WarmWhite, and Daylight). As the lamp, there are a three-wavelength fluorescent lamp that emits white light by mixing these three color phosphors (blue red green), and a general color fluorescent lamp using a calcium halophosphate phosphor.

There is a case where both lamps are mixed in the phosphor waste generated in the manufacturing process of the fluorescent lamp. In many cases, phosphors collected from used fluorescent lamps are mixed with calcium halophosphate phosphors and phosphors of three colors. Further, the blue phosphor cannot be reused because Eu ²⁺ which is a light emitting element deteriorates to Eu ³⁺ by heating or the like. For these reasons, it is difficult to use the recovered phosphor as it is. Therefore, it is desired to separate phosphors for each type from a mixture of a plurality of types of phosphors.

As a method for separating phosphors by type, a method using a collecting agent using a zeta potential difference (see Japanese Patent Application Laid-Open No. 2004-83869), a method using solution separation using an aqueous or oil-based solvent (Japanese Patent Application Laid-Open No. 2004-2004). -262978), a method using a charged state (see Japanese Patent Application Laid-Open No. 2004-137320), and the like are known. However, these methods have a drawback that it is necessary to change a reagent or an apparatus for each phosphor intended for separation, and complicated treatment is required when separating various phosphors. In addition, these separation methods are performed by utilizing the surface potential or adsorption characteristics, and may not be separated when the surface state of the phosphor changes due to product processing or the like.

On the other hand, a method using a high magnetic field gradient magnetic separator is known as an industrial method for separating substances having different magnetic susceptibility using a high magnetic field gradient, although it does not separate phosphors. In this method, a magnetic material is attached to the wire, steel wool, etc. by arranging a column packed with ferromagnetic wire, steel wool, etc. in the magnetic field and circulating the separation object therein (hereinafter referred to as magnetic adhesion). (Referred to as Japanese Patent Laid-Open No. 11-47632 (hereinafter referred to as' 632)).

It is conceivable to apply a high magnetic field gradient magnetic separator as disclosed in the '632 publication to the separation of phosphors. In this case, the high magnetic field gradient magnetic separator is effective for adsorbing and separating a magnetic material from nonmagnetic materials, but cannot be applied as it is to a mixture of fine powders due to the structure of the apparatus. That is, the mixture of different types of phosphors collected from a used fluorescent lamp is an aggregate of fine powders, so that it has low wettability and high degree of adsorption to metal materials, and the magnetic susceptibility depending on the type of phosphor. Since the separation efficiency is low due to the small difference between the two, it is difficult to apply a high magnetic field gradient magnetic separator for the type separation of phosphors.

Therefore, an object of the present invention is to provide a method for separating a phosphor mixture that efficiently separates a phosphor from a mixture of a plurality of types of phosphor fine powders having different magnetic susceptibility.

The above objective can be achieved by the following.

That is, the method for separating a phosphor mixture according to the present invention includes a step of dispersing a mixture composed of a plurality of types of phosphors having different magnetic susceptibilities in a dispersion medium to prepare a mixture, and a mixture in the processing vessel. An installation step of positioning a filter formed of a ferromagnetic material in the mixed solution, and a mixed solution recovery step of discharging and recovering the mixed solution from the processing container with a magnetic field applied to the filter, The dispersion medium is a solution in which a low molecular surfactant is added to an aqueous solution of a polymer dispersant.

Preferably, the installation step and the mixed solution recovery step are repeated using the recovered solution obtained in the mixed solution recovery step as a new mixed solution.

More preferably, the method for separating the phosphor mixture further includes a washing step of washing the filter with a dispersion medium in a state where a magnetic field is applied and collecting the dispersion medium used for washing the filter, following the mixed solution collecting step.

More preferably, the installation step, the mixed solution recovery step, and the cleaning step are repeated using the recovered solution from the cleaning step as a new mixed solution.

Preferably, the method for separating the phosphor mixture further includes a magnetized material collection step of washing the filter with a dispersion medium in a state where the applied magnetic field is reduced, and collecting the dispersion medium used for washing the filter.

More preferably, the installation step, the mixed solution recovery step, and the magnetic deposit recovery step are repeated using the recovery solution from the magnetic deposit recovery step as a new mixed solution.

More preferably, the method for separating the phosphor mixture further includes a step of vibrating the filter in a state where a magnetic field is applied to the filter positioned in the mixed solution before the mixed solution collecting step.

Preferably, the polymer dispersant is a polycarboxylic acid polymer dispersant.

More preferably, the low molecular weight surfactant is amide propyl betaine laurate, sodium polyoxyethylene lauryl ether sulfate, polyoxyalkylene nonionic surfactant, polyoxyalkylene alkyl ether, polyhydric alcohol nonionic interface. It is a neutral detergent containing an activator or sodium alkyl ether sulfate.

More preferably, the concentration of the polymeric dispersant is 0.02% to 3%, and the concentration of the low molecular surfactant is 0.004% to 0.1%.

A phosphor mixture separation apparatus according to the present invention includes a processing container that contains a mixture liquid containing a mixture of phosphors having different magnetic susceptibility and a filter formed of a ferromagnetic material therein, and a mixture. A magnetic field generating unit that applies a magnetic field to the filter while being accommodated in the processing container, and a recovery unit that discharges and recovers the mixed liquid from the processing container in a state where the magnetic field is applied to the filter. Is a liquid in which a mixture is dispersed in a dispersion medium, which is a solution obtained by adding a low molecular surfactant to an aqueous solution of a polymer dispersant.

According to the present invention, since a solution obtained by adding a low molecular weight surfactant to an aqueous solution of a polymeric dispersant is used as a dispersion medium of the phosphor mixture, the wettability to the phosphor is high, and after reducing the magnetic field It can suppress that the fluorescent substance remains adhering to a filter, and can isolate | separate fluorescent substance for every kind efficiently.

The purity of the specific phosphor can be increased by repeating the separation process for the recovered liquid obtained by the separation process of the phosphor-containing dispersion.

It is a block diagram which shows the outline | summary of a structure of the apparatus used for the isolation | separation method of the fluorescent substance mixture which concerns on embodiment of this invention. It is a flowchart which shows the separation method of the fluorescent substance mixture which concerns on embodiment of this invention. It is a table | surface which matches and shows the dispersing agent which has surface active effect | action, and the evaluation result of adhesiveness. It is a table | surface which shows an experimental result.

In the following embodiments, the same reference numerals are assigned to the same parts. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

The phosphor mixture to be separated in the present embodiment is a mixture of phosphors in the form of fine powder (particle size on the order of μm, for example, 10 μm or less) collected by recycling a used fluorescent lamp. The phosphor obtained by the recycling treatment is not usually a single type of phosphor, but a mixture of a blue phosphor, a red phosphor, a green phosphor, a white phosphor (halophosphoric acid daylight phosphor), and the like. Therefore, in order to reuse this, it is essential to separate the phosphors of the respective colors.

Referring to FIG. 1, the apparatus used in the phosphor mixture separation method according to the present embodiment includes a processing tube 100, a filter 102, a magnetic field generation unit 104, a vibration unit 106, a charging unit 108, and a charging valve 110. And a discharge valve 112.

The processing tube 100 temporarily stores a solution (hereinafter also referred to as input solution) supplied from the input unit 108. The filter 102 is formed of a ferromagnetic material and is a structure (for example, a mesh structure or an aggregate of fibrous materials) through which a dispersion liquid in which a phosphor described later is dispersed can pass through the filter 102. Placed in. The filter 102 is made of, for example, an expanded metal made of magnetic stainless steel or stainless wool. The filter is also called a matrix in a magnetic separator using a known gradient magnetic field.

The charging valve 110 can be opened and closed. When the charging valve 110 is opened, the charging solution 140 is charged into the processing tube 100. When the charging valve 110 is closed, the charging of the charging solution 140 into the processing tube 100 is stopped. The discharge valve 112 can be opened and closed. When the discharge valve 112 is opened, the liquid in the processing tube 100 is discharged from the discharge port. The discharged liquid is collected by the collection container 114. When the discharge valve 112 is closed, the discharge is stopped and the introduced liquid is held in the processing tube 100.

The magnetic field generation unit 104 includes magnetic poles (pole pieces) 120 and 122 and coils 124 and 126. When a predetermined current is supplied to the

coils

124 and 126 from a power source (not shown), the magnetic field generation unit 104 generates a magnetic field having a strength corresponding to the current value in a region where the filter 102 is disposed. The

magnetic poles

120 and 122 are for converging the magnetic field generated by the

coils

124 and 126 to form a strong magnetic field. The magnetic field generation unit 104 may not include the

magnetic poles

120 and 122 as long as a magnetic field with a predetermined strength can be formed. Here, the magnetic field is formed so that the magnetic field direction 130 is orthogonal to the processing tube 100, but an electromagnet that forms a magnetic field in a direction along the processing tube 100 may be used. For example, the processing tube 100 may be disposed in a cylindrical solenoid coil.

The vibration unit 106 vibrates the processing tube 100 at a predetermined frequency in order to vibrate the filter 102. Since the phosphor particles to be separated are on the order of μm, the frequency is preferably a high-frequency frequency such as an ultrasonic wave, but may be a frequency of 100 Hz or less.

The outline of the separation process using this device is as follows. The phosphor mixture is dispersed in a predetermined dispersion medium (liquid) to prepare an input liquid 140. The input valve 110 is opened, and the input liquid 140 is input into the processing tube 100 from the input unit 108. In this state, the magnetic field generator 104 generates a magnetic field near the filter 102. As a result, the filter 102 of the ferromagnetic material is magnetized, and a gradient magnetic field (a magnetic field in which the magnetic field strength is not uniform but varies spatially) is formed around it. At the same time, since the phosphor is magnetized, the phosphor receives a force by the gradient magnetic field, is attracted to the filter 102, and adheres to the filter 102.

At this time, if the processing tube 100 is vibrated by the vibration unit 106, the phosphor separation efficiency can be increased. Phosphors have different magnetic susceptibility depending on the type, and therefore the adhesion strength to the filter 102 is different. Table 2 shows an example of the magnetic susceptibility of the phosphor. The phosphor particles having a high magnetic susceptibility adhere more firmly to the filter 102 and are difficult to be separated from the filter 102 even when subjected to vibration. On the other hand, phosphor particles having a low magnetic susceptibility cannot be stably attached to the filter 102 due to vibration, and are easily separated from the filter 102 and away from the filter 102. Therefore, by separating the filter 102, the separation efficiency of the mixed phosphor can be increased.

In Table 2, the magnetic susceptibility of each phosphor is expressed as magnetization (eu / g) per unit mass (1 g) when the magnetic field strength is 1000 Gauss. Table 2 is an example, and the composition may differ depending on the manufacturer even if the phosphors have the same color. Moreover, even if it is the same manufacturer, the composition of the fluorescent substance of the same color may change with model numbers.

Thereafter, the discharge valve 112 is opened, and the dispersion liquid in the processing tube 100 is recovered. The recovery rate for each phosphor (ratio of the amount collected relative to the amount initially contained in the dispersion) has a relatively high magnetic susceptibility and a high value for the phosphor that is difficult to adhere to the filter 102 (it adheres weakly). The value of the phosphor having a relatively high magnetic susceptibility and easily attached (strongly attached) to the filter 102 is low. Further, when the filter 102 is taken out from the processing tube 100 after the discharge and the adhering phosphor is collected, the recovery rate is a value of the phosphor that has a relatively low magnetic susceptibility and is difficult to adhere to the filter 102 (weakly adhering) And the value of the phosphor that has a relatively high magnetic susceptibility and easily adheres (strongly adheres) to the filter 102 is high. Therefore, by repeating the above processing using the collected phosphor mixture as a separation target, the mixed phosphor can be separated according to the magnetic susceptibility.

Hereinafter, with reference to FIG. 2, the above-described phosphor separation method and a dispersion medium suitable therefor will be described in more detail.

Prepare in step 200. Specifically, the filter 102 is disposed in the processing tube 100, and the phosphor mixture to be separated is dispersed in a dispersion medium to produce a phosphor-containing dispersion. When water is used as a dispersion medium, it is necessary to add a dispersant having a surface active action in order to prevent aggregation of the phosphor powder.

A commercially available neutral detergent can be used as the dispersant. However, since a commercially available neutral detergent has a strong foaming property, when a filter 102 (magnetic stainless steel expanded metal, stainless wool, or the like) is circulated, a large amount of bubbles are generated and difficult to disappear. It will be an obstacle.

In addition, when a dispersant having poor wettability to the phosphor is used, a cleaning liquid is flowed after lowering the magnetic field, and the phosphor adhering to the filter 102 by magnetization (hereinafter also referred to as a magnetized phosphor) is recovered. In this case, the phosphor is not easily detached from the filter 102 and the phosphor is likely to remain on the filter 102. For this reason, a large amount of cleaning liquid is required for recovery, which is an obstacle to performing a plurality of treatments.

As the dispersing agent, it is necessary to use a dispersing agent that has good wettability of the phosphor, does not cause aggregation, and does not collect the phosphor on the surface of the dispersion and the generated foam surface. Specifically, a polymeric dispersant and a foaming low molecular surfactant are used as the dispersant, and these are added to water at a predetermined ratio to produce a dispersion medium for dispersing the phosphor. To do. The polymer dispersant is preferably a polycarboxylic acid dispersant.

By using such a combination of dispersing agents, as will be described later, the amount of residual phosphor after washing for recovering the magnetized phosphor is suppressed to less than 2%, and the foam layer is formed in a short time after the treatment. Can be eliminated.

In step 202, a magnetic field is applied to the filter 102. Specifically, the magnetic field generator 104 is energized to generate a magnetic field in the region where the filter 102 is disposed. The magnitude of the applied magnetic field varies depending on the type of phosphor to be separated and the filter (matrix). For example, when using a green phosphor with a high magnetic susceptibility and using stainless steel with a thin wire diameter, the magnitude of the applied magnetic field is 1T or less, and the target is a blue phosphor with a low magnetic susceptibility. Is preferably 2T or more.

In step 204, a dispersion medium in which the phosphor is not dispersed (hereinafter also referred to as a phosphor-free dispersion liquid) is introduced into the processing tube 100 through the introduction unit 108 and the introduction valve 110 to the lower end of the filter 102.

In Step 206, a phosphor-containing dispersion liquid (liquid in which a phosphor mixture is dispersed in a dispersion medium) is introduced into the processing tube 100 through the introduction unit 108 and the introduction valve 110 to the upper end of the filter 102.

In Step 208, a predetermined amount of the phosphor-free dispersion is introduced into the processing tube 100 through the introduction unit 108 and the introduction valve 110. As a result, the phosphor-free dispersion, the phosphor-containing dispersion, and the phosphor-free dispersion stay in the processing tube 100 from below.

In step 210, the vibration processing unit 106 vibrates the processing tube 100 at a predetermined frequency for a predetermined time.

In step 212, the discharge valve 112 is opened, and all the liquid in the processing tube 100 is discharged and recovered in the recovery container 114. Since the adhesion strength to the filter 102 differs according to the magnetic susceptibility of the phosphors mixed as described above, it is assumed that the same amount of phosphors is initially contained. The more the phosphor, the lower the magnetic susceptibility.

In step 214, the inside of the processing tube 100 is washed with a phosphor-free dispersion, and the discharged liquid is collected. Specifically, the discharge valve 112 is closed, and a predetermined amount of the phosphor-free dispersion is introduced into the processing tube 100 through the introduction unit 108 and the introduction valve 110. Thereafter, the discharge valve 112 is opened, and the phosphor-free dispersion in the processing tube 100 is discharged and collected in the collection container 114. In order to prevent the recovery liquid 142 from being mixed, for example, a different container is used as the recovery container 114 each time.

In step 216, it is determined whether or not the predetermined number of times of cleaning has been completed. That is, until it is determined that the cleaning is completed, the cleaning and recovery processing in step 214 is repeated a predetermined number of times, and then the processing proceeds to step 218. In the cleaning and recovery process in step 214, the phosphor-free dispersion liquid may be passed through the processing tube 100 at an increased flow rate while the discharge valve 112 is open.

In step 218, the value of the current supplied to the magnetic field generator 104 is decreased to decrease the magnetic field strength (including the case where the magnetic field strength is set to 0). For example, the magnetic field strength is reduced to less than 0.2T.

In step 220, the inside of the processing tube 100 is washed with a phosphor-free dispersion, and the discharged liquid is collected. Since the adhesion strength to the filter 102 differs according to the magnetic susceptibility of the phosphors mixed as described above, if the same amount of phosphor is initially included, the liquid recovered in step 220 The phosphor contains more phosphors with higher magnetic susceptibility. That is, the phosphor having a high magnetic susceptibility is likely to remain attached to the filter 102 by the magnetic force even during the cleaning process of step 214 that is repeatedly performed.

In step 222, it is determined whether or not to end. That is, until it is determined that the process is completed, the process of steps 202 to 220 is repeated using any one of the collected liquids collected a plurality of times so as not to mix.

As described above, the content of each phosphor contained in the liquid collected in step 212 and step 220 is different from the content of each phosphor contained in the phosphor-containing dispersion before processing. The recovered liquid obtained in step 212 has a higher phosphor content in the phosphor mixture than in the phosphor-containing dispersion charged in step 206. The recovered liquid in step 220 has a higher phosphor content in the phosphor mixture than in the phosphor-containing dispersion charged in step 206. Accordingly, by repeating the processes of steps 202 to 220 using the recovery liquid at a predetermined step, a recovery liquid having a high content of a specific phosphor can be obtained. For example, the content of the phosphor having the lowest magnetic susceptibility among the phosphors contained in the phosphor mixture in the recovered liquid is obtained by repeating the introduction of the recovered liquid in step 212 into the processing tube 100 in step 206. Can be high. Further, by repeating the charging of the recovery liquid in step 220 into the processing tube 100 in step 206, the content ratio of the phosphor having the highest magnetic susceptibility among the phosphors contained in the phosphor mixture in the recovery liquid. Can be high. Therefore, as the number of repetitions increases, the purity of the specific phosphor can be increased. In addition, it is desirable to determine which step of the recovered liquid is repeatedly used by analyzing the type and content rate of the phosphor initially contained in the phosphor mixture.

Hereinafter, the dispersant used for preparing the phosphor-containing dispersion and the phosphor-free dispersion will be described in more detail.

It is possible to evaluate whether or not the dispersibility is good by mixing the phosphor fine powder and the dispersion (water added with a dispersant) and shaking. Further, a dispersing agent that does not allow the phosphor to adhere to the filter 102 is preferable. This is done by placing the filter 102, for example, a stainless steel expanded metal, in a shaking liquid (liquid immediately after the shaking is finished), and then taking out the filter 102 (stainless steel expanded metal) and washing it with the dispersion. It can be evaluated by confirming whether or not the phosphor is attached.

FIG. 3 shows the results of examining the adhesion of various dispersants having a surface active action. The percentage value described after the dispersant name means the amount added (% by weight). In the dispersibility column, “A” means good dispersibility, “C” means poor dispersibility, and “B” means the middle of them. The description of the foaming column means the presence or absence of foaming and the strength of foaming. The description in the column of adhesion indicates adhesion to the filter (stainless steel expanded metal), “A” means no adhesion, “C” means high adhesion, “B” means slight adhesion. .

When an adhesive dispersion is used, the phosphor remains on the filter after the phosphor separation, and it is not preferable because it needs to be washed with a large amount of the dispersion. In FIG. 3, many non-foaming (foaming “no”) or microfoaming (foaming “weak”) dispersants have a high surface tension. Regarding these, it is possible to improve wettability, eliminate adhesion to the filter, and enhance dispersibility by adding a low molecular surfactant having strong permeability. As a dispersant for producing a dispersion liquid with good wettability of the phosphor and difficult to adhere the phosphor to the filter, a small amount of penetrating surfactant is added to the polymer type dispersant as the main dispersant. The dispersing agent obtained by adding can be mentioned.

Examples of the polymeric dispersant used as the main dispersant include polycarboxylic acid, naphthalene sulfonic acid formalin condensation system, and polyethylene glycol. Considering the use of the phosphor after separation, polycarboxylic acid-based dispersants (see No. 1 and No. 2 in FIG. 3) that do not contain ash such as sodium and halogen are particularly preferable.

The concentration of the main dispersant must be at least the concentration at which the phosphor is not aggregated and dispersed. On the other hand, if the dispersant concentration is too high, the viscosity may increase and the separation efficiency may decrease, and it takes time to remove the dispersant after the phosphor separation. Therefore, the concentration (% by weight) of the dispersant in the dispersion is 0.02% to 3%, preferably 0.03% to 1%, more preferably 0.03% to 0.3%.

As a penetrating surfactant to be added in a trace amount (hereinafter also referred to as an additive), any surfactant such as a nonionic surfactant, an anionic surfactant, or an amphoteric surfactant may be used. good. Polyoxyethylene alkyl ether or polyhydric alcohol nonionic surfactant (see Example 1 described later) as a nonionic surfactant, linear sodium alkylbenzene sulfonate or polyoxy as an anionic surfactant Examples of amphoteric surfactants such as sodium ethylene alkyl ether sulfate include alkyl betaines. Moreover, the commercially available neutral detergent containing said component can also be used as an additive. Considering use after separation, nonionic surfactants such as polyoxyethylene alkyl ethers (No. 11 in FIG. 3) and betaines (see No. 22 in FIG. 3) that do not contain any ash such as sodium or halogen. ) And the like are particularly preferred. The foamability of the additive (surfactant) is preferably 80 mm or more immediately after the measured value by the foaming force test defined by JIS K3362 at a concentration of 1%.

If the concentration of the additive is too low, there is no effect of improving wettability, and the phosphor remains in the filter even after recovery of the magnetized phosphor by washing after demagnetization. If the concentration is too high, foaming is severe and a foam layer remains for a long time after the treatment, which hinders the recovery process by filtration after separation. For this reason, the concentration of the additive in the dispersion is 0.004% to 0.1%, preferably 0.005% to 0.05%, more preferably 0.01% to 0.02%. Further, the foaming power of the dispersion obtained by adding the additive to the dispersant is preferably less than 3 mm after 5 minutes.

In the above description, the phosphor-free dispersion liquid is disposed above and below the phosphor-containing dispersion liquid in the processing tube 100. However, the present invention is not limited to this, and the upper phosphor-free dispersion liquid may be omitted. Further, if the filter 102 is positioned in the phosphor-containing dispersion, the lower phosphor-free dispersion may not be present.

In addition, although the case where the filter 102 is vibrated has been described, it is not necessary to vibrate. If the vibration is not applied, the dispersion efficiency is lower than that when the vibration is applied, but the phosphor can be separated by increasing the number of repetitions of the treatment.

In the above description, the case where the phosphor-containing dispersion is held in the processing tube 100 has been described, but the present invention is not limited to this. As long as the phosphor-containing dispersion liquid can be held in a state where the filter 102 is disposed in the phosphor-containing dispersion liquid, a container having an arbitrary shape is not limited to a tubular shape.

In the above description, the case where the filter 102 is washed in a state where a magnetic field having a predetermined intensity or more is applied has been described, but the present invention is not limited to this. The magnetic deposit may be recovered by cleaning the filter 102 in a state where the magnetic field is reduced, without performing cleaning in a state where a magnetic field having a predetermined strength or higher is applied.

In the above description, the case has been described in which the separation process is repeated using the recovered liquid as a processing target as it is, but the present invention is not limited to this. If necessary, prepare a fine powder phosphor mixture from the collected liquid by filtration, drying treatment, etc., analyze the phosphor content ratio, and then use this phosphor mixture as needed to make a phosphor-containing dispersion. And the above separation process may be executed.

In the above description, the case where the separation process is repeatedly performed using the collected liquid collected in any step has been described, but the present invention is not limited to this. If the contents of the phosphors contained in the collected liquid are substantially the same, a separation process may be performed on the liquid obtained by mixing the collected liquids.

The experimental results are shown below to show the effectiveness of the present invention.

A phosphor-free dispersion was prepared by changing the blending concentration in water with the combination of the dispersant shown in FIG. 3 as the main dispersant and additive. In this dispersion liquid 0.2 L (liter), blue phosphor BAM (LP-B4 manufactured by Mitsubishi Chemical Corporation, measured value of magnetic susceptibility 1.53 × 10 ⁻⁴ H / m) and red phosphor YOX (Mitsubishi Chemical Corporation) A phosphor-containing dispersion was prepared by dispersing 0.5 g each of LP-RE1 (manufactured by company, measured value of magnetic susceptibility 0.83 × 10 ⁻⁴ H / m). Experiments were performed according to the procedure shown in FIG. 2 using this phosphor-containing dispersion as a target for separation treatment. In addition, the phosphor non-containing dispersion liquid used for preparation of each phosphor containing dispersion liquid was used for the cleaning liquid.

A well-known Elise Magnetics magnetic separator (model HIW L4-20K) was used, and a stainless steel wool (length: about 20 cm, width: about 5 cm, thickness: about 2 cm) made of SUS430 was used for the filter (matrix). After applying a 2T magnetic field to the filter with this magnetic separator, the phosphor-free dispersion and the phosphor-containing dispersion were filled in the processing tube as described above. In this state, the treatment tube was vibrated for 30 seconds using a massager manufactured by OMRON Corporation as a vibration device, and the discharge valve was opened to collect the phosphor not attached to the filter. Next, as the first cleaning, the discharge valve was once closed and 0.5 L of cleaning liquid was poured into the processing tube, and then the discharge valve was opened to clean the filter, and the discharged liquid was collected. Further, as the second washing, the filter was washed again by increasing the flow rate with 0.5 L of washing liquid while the discharge valve was opened, and the discharged liquid was collected. Thereafter, the power supply was turned off to reduce the magnetic field to 0, and 0.5 L of a cleaning solution was circulated to collect the phosphor that was magnetically attached to the filter. Further, about 1 L of the cleaning liquid was passed through the processing tube, and the amount of phosphor remaining on the filter was examined.

The result is shown in FIG. In the column “Evaluation” in FIG. 4, comprehensive evaluation is described. “A” represents a case suitable for the separation of the phosphors, and “C” represents a case unsuitable. PCA1 is a special polycarboxylic acid-based dispersant, Poise (registered trademark) 520 manufactured by Kao Corporation, PCA2 is a special polycarboxylic acid-based dispersant, Kaorcera (registered trademark) 2000 manufactured by Kao Corporation, and PCA3 is an ammonium polycarboxylate Nopco Santo RFA manufactured by San Nopco Co., Ltd., which is a dispersant, LAB is Amphital (registered trademark) 20AB manufactured by Kao Corporation, which is amidopropyl betaine laurate, and SPAL is sodium polyoxyethylene lauryl ether sulfate. ) 20C, PAAE is a polyoxyalkylene-based SN wet 980 manufactured by San Nopco, PAAE is a polyoxyalkylene alkyl ether, Nippon Emulsifier Co., Ltd. Newcol 2308LY, a polyhydric alcohol is a polyhydric alcohol It represents the San Nopco Co. Nopco Wet SN-20T is a nonionic surfactant.

In the “mixed liquid distribution” column, the result of analyzing the first recovered liquid is described. The upper part of each cell shows the ratio (% by weight) of the red phosphor and the blue phosphor, and the lower part shows the total weight. For example, no. In No. 1, a total of 248 mg of the phosphor was recovered from the first recovery liquid, and the breakdown shows that the red phosphor was 58% and the blue phosphor was 42%. In the column “First Wash”, the result of analyzing the collected liquid of the first wash is similarly described. The same applies to the “second cleaning” column. The column “Recovery of magnetic deposits” relates to the recovered liquid in a state where the magnetic field is reduced, and the column “Remaining amount” relates to the phosphor recovered by the last washing (phosphor remaining in the filter). , As well. In addition, No. 19 shows the result when vibration is not applied to the filter.

As can be seen from the phosphor content shown in FIG. 4, in the entire experiment, the ratio of the red phosphor having a low magnetic susceptibility is high in the first recovered liquid (mixed liquid circulation column). The ratio of blue phosphors was high in the recovery liquid (line of magnetized material recovery) by washing with the body ratio increased and the magnetic field decreased. This depends on the difference in magnetic susceptibility between the red phosphor and the blue phosphor.

In the case of using Pois 520 manufactured by Kao Co., Ltd., which is a special polycarboxylic acid polymer surfactant for dispersing pigments as a polymer dispersant, as the main dispersant alone (see No. 1), The remaining phosphor at the time of re-washing was as high as 6% or more (62 mg with respect to the initial amount of 1000 mg).

In the case where Amophor 20AB manufactured by Kao Co., Ltd., which is a foaming surfactant, lauramide amidopropyl betaine, is used as an additive, and the concentration is changed, the concentration of the remaining phosphor is 0.003% (see No. 2). There were many. However, when the concentration was in the range of 0.015% to 0.05% (see No. 3 and No. 4), the amount of the remaining phosphor was reduced, which was effective. When the concentration exceeded 0.05%, the amount of the remaining phosphor was small, but the foaming property increased, and it took 1 hour or more for disappearance of the foam layer.

When the concentration of the main dispersant is lowered, no. As shown in FIG. 5, even with 0.03%, the amount of residual phosphor was as low as 1.2% (12 mg with respect to the initial amount of 1000 mg), which was effective. Although not shown in FIG. 4, when the concentration of the dispersant was 0.015%, the phosphor powder aggregated and was not dispersed.

Regarding the type of additive, polyoxyethylene alkyl ether sodium sulfate (Emal 20C manufactured by Kao Corporation), a neutral detergent (Kao Family Fresh containing sodium alkyl ether sulfate ester), or a fine foaming surfactant When foaming polyoxyalkylene nonionic surfactant (SN wet 980 manufactured by San Nopco Co., Ltd.) or polyoxyalkylene alkyl ether (Newcol 2308-LY manufactured by Nippon Emulsifier Co., Ltd. was added at a concentration of 0.015%, respectively (No. 6 to No. 9) was also effective with a small amount of residual phosphor.

As the main dispersant, concentration of Kaocera 2000 made by Kao Co., Ltd., which is a special polycarboxylic acid-based dispersant for dispersing ceramic powder, which is a polymer type dispersant, or Nopco Santo RFA made by San Nopco, Inc., which is a polycarboxylic acid ammonium dispersant Even when 0.15% was used and a foaming surfactant was added at a concentration of 0.015% (see No. 10 and No. 11), the amount of residual phosphor was small and effective.

When p-toluenesulfonic acid Na, which is a non-foaming surfactant, was added at a concentration of 0.2% as an additive (see No. 12), the residual amount exceeded 10% and was not effective.

When non-polymeric polyoxyethylene sorbitan monolaurate (Tween 20) is used as a main dispersant at a concentration of 0.05%, and LAB as an additive is added at a concentration of 0.01% (see No. 13) When polyoxyethylene sorbitan trioleate (Tween 85) is used as a main dispersant at a concentration of 0.05%, and LAB is added as an additive at a concentration of 0.015% (see No. 14), the main dispersant When a non-polymeric microfoaming polyoxyalkylene alkyl ether (PAAE) is used at a concentration of 0.15% and LAB is added as an additive at a concentration of 0.03% (see No. 15), and , A commercial dishwasher detergent mainly composed of polyoxyalkylene alkyl ether as a main dispersant is used at a concentration of 0.15% and added to this Even when the addition of LAB concentration of 0.01% (see No.16) as the residual amount of the phosphor is often was not effective.

When sodium hexametaphosphate, which is an inorganic dispersant, was used as the main dispersant at a concentration of 0.15% (see No. 17), the remaining amount was large and was not effective.

When a commercially available neutral detergent was used as the main dispersant at a concentration of 0.15% (see No. 18), the separation efficiency was good and the residual amount was less than 1%. There was a foam layer on top.

No. When the same combination of the main dispersant and additive as in No. 3 was used and no vibration was applied (see No. 19), the total amount of phosphor contained in the first recovered liquid (mixed liquid flow) was No. 3. 3 and the ratio of the blue phosphor is No. 3. Lower than in case of 3. This indicates that the adhesion efficiency of the magnetized phosphor to the filter is poor, and in particular, the adhesion efficiency of the blue phosphor having a high magnetic susceptibility to the filter is poor. Therefore, the separation efficiency can be increased by applying vibration.

As mentioned above, No. 3 to No. Eleven primary dispersant and additive combinations were suitable. In these cases, the first recovered liquid (mixed liquid circulation) contains red phosphor at a ratio of about 60%. By repeating the separation process using this recovered liquid, the high-purity red phosphor is obtained. Obtainable. Since the red phosphor is also contained in the recovery liquid (first wash) obtained by the first washing at a ratio of about 60%, a red phosphor with high purity can be obtained similarly.

In addition, since the recovery liquid (magnetized substance recovery) in a state where the magnetic field is reduced contains blue phosphor in a ratio exceeding 60%, the separation process is repeated using this recovery liquid to reduce the magnetic field. A blue phosphor having a high purity can be obtained from the recovered liquid in a fresh state.

Blue phosphor BAM (Mitsubishi Chemical Corporation LP-B2, measured value of magnetic susceptibility 1.8 × 10 ⁻⁴ H / m), Green phosphor LAP (Mitsubishi Chemical Corporation LP-G2, measured value of magnetic susceptibility) 1.6 × 10 ⁻³ H / m) and red phosphor YOX (LP-RE1 manufactured by Mitsubishi Chemical Corporation, measured value of magnetic susceptibility 0.83 × 10 ⁻⁴ H / m) 1.0 g each was dispersed. A phosphor-containing dispersion liquid 0.2 L was prepared, and the phosphor was separated. As the dispersion medium, No. 1 of Example 1 was used. 3, Pois 520 manufactured by Kao Co., Ltd., which is a special polycarboxylic acid polymer surfactant for dispersing pigments as a polymer dispersant, is used as a main dispersant, and propyl betaine laurate is used as an additive. Anhitol 20AB manufactured by Kao Corporation was used. These are mixed with water at concentrations of 0.15 and 0.015%, respectively, to prepare a dispersion medium (phosphor-free dispersion), in which the above three colors of phosphors are dispersed, and phosphors are contained. A dispersion was prepared.

The experimental results are shown in Table 3.

From Table 3, the collected liquid in the first distribution (mixed liquid distribution column) contains almost no green phosphor, and the mixture obtained from this collected liquid is a mixture of red and blue phosphors. It can be said. This contains many red phosphors with low magnetic susceptibility. The ratio of the blue phosphor increases in the collected liquid by the first washing (first washing column), and the blue phosphor is contained in the collected liquid by the second strong washing (second washing column). became. This is because a large number of red phosphors having the lowest magnetic susceptibility among the three color phosphors were discharged before the first cleaning.

In the recovered liquid obtained by washing with a reduced magnetic field (column for recovering magnetic deposits), the content of the green phosphor was 80%. This indicates that the green phosphor had a high magnetic susceptibility and was stably magnetized on the filter. Furthermore, almost no phosphor remained in the liquid recovered by rewashing (column of residual amount).

From the above, it can be seen that the combination of the main dispersant and the additive suitable in Example 1 is also effective for the separation of the phosphor mixture containing the green phosphor. It can also be seen that separating the green phosphor from the phosphor mixture is easier than separating the blue and red phosphors.

A phosphor-free dispersion was prepared using the same main dispersant and additive as in Example 2, and a blue phosphor BAM (LP-B4 manufactured by Mitsubishi Chemical Corporation, measured value of magnetic susceptibility 1.5 × 10 ⁻⁴ H / m) and 1.0 g each of halophosphoric daylight phosphor (Daylight manufactured by Nichia Chemical Co., Ltd., measured value of magnetic susceptibility 0.39 × 10 ⁻⁴ H / m) are dispersed in the phosphor-containing dispersion liquid. 0.2 L was produced, and the phosphor was separated. The intensity of the applied magnetic field is 2T.

The results are shown in Table 4.

From Table 4, the collected liquid in the first distribution (mixed liquid distribution column) contains a lot of halophosphate daylight color phosphors with low magnetic susceptibility, and the ratio of blue phosphors increases and the magnetic field decreases with repeated washing. There were many blue phosphors in the collected liquid (line of magnetic deposit collection) by washing in the wet state. In addition, almost no phosphor remained in the liquid recovered by re-washing (column of residual amount). Therefore, it can be seen that the combination of the main dispersant and the additive suitable in Example 1 is also effective in separating the halophosphate daylight phosphor.

According to the present invention, it is possible to provide a method and an apparatus for efficiently separating a phosphor from a mixture composed of a plurality of types of phosphor fine powders having different magnetic susceptibility.

100 Processing tube 102 Filter 104 Magnetic field generation unit 106 Excitation unit 108 Input unit 110 Input valve 112 Discharge valve 114

Recovery container

120, 122

Magnetic poles

124, 126 Coil 130 Magnetic field direction 140 Input liquid 142 Recovery liquid

Claims

A step of dispersing a mixture of phosphors having different magnetic susceptibilities in a dispersion medium to produce a mixed solution;
Placing the mixed solution in a processing vessel and positioning a filter formed of a ferromagnetic material in the mixed solution;
A mixed liquid recovery step of discharging and recovering the mixed liquid from the processing container in a state where a magnetic field is applied to the filter,
The method for separating a phosphor mixture, wherein the dispersion medium is a solution obtained by adding a low molecular surfactant to an aqueous solution of a polymer dispersant.
The method for separating a phosphor mixture according to claim 1, wherein the installation step and the mixed solution collecting step are repeated using the collected solution obtained in the mixed solution collecting step as a new mixed solution.
2. The fluorescence according to claim 1, further comprising a cleaning step of cleaning the filter with the dispersion medium in a state where the magnetic field is applied, and recovering the dispersion medium used for cleaning the filter following the liquid mixture recovery step. Separation method of body mixture.
4. The method for separating a phosphor mixture according to claim 3, wherein the collection liquid obtained in the washing step is used as a new mixed liquid, and the installation step, the mixed liquid collection step, and the washing step are repeated.
2. The phosphor according to claim 1, further comprising a magnetized substance recovery step of cleaning the filter with the dispersion medium in a state where the applied magnetic field is reduced, and recovering the dispersion medium used for cleaning the filter. Method for separating the mixture.
6. The method for separating a phosphor mixture according to claim 5, wherein the installation liquid, the mixed liquid recovery step, and the magnetic deposit recovery step are repeated by using the recovered liquid from the magnetic deposit recovery step as a new mixed liquid.
The method for separating a phosphor mixture according to claim 1, further comprising a step of vibrating the filter in a state where the magnetic field is applied to the filter positioned in the mixed solution before the mixed solution collecting step.
The method for separating a phosphor mixture according to claim 1, wherein the polymer-type dispersant is a polycarboxylic acid-based polymer dispersant.
The low molecular weight surfactant includes amide propyl betaine laurate, sodium polyoxyethylene lauryl ether sulfate, polyoxyalkylene nonionic surfactant, polyoxyalkylene alkyl ether, polyhydric alcohol nonionic surfactant, Or the separation method of the fluorescent substance mixture of Claim 1 which is a neutral detergent containing alkyl ether sulfate ester sodium.
The concentration of the polymeric dispersant is 0.02% to 3%,
The method for separating a phosphor mixture according to claim 1, wherein the concentration of the low molecular surfactant is 0.004% to 0.1%.
A processing container that contains a mixed solution containing a mixture of phosphors having different magnetic susceptibility and a filter formed of a ferromagnetic material inside,
A magnetic field generator for applying a magnetic field to the filter in a state where the mixture is contained in the processing container;
In a state where a magnetic field is applied to the filter, a recovery unit that discharges and recovers the mixed liquid from the processing container,
The phosphor mixture separation apparatus, wherein the mixture is a liquid in which the mixture is dispersed in a dispersion medium, which is a solution obtained by adding a low molecular surfactant to an aqueous solution of a polymer dispersant.