JPH11123302A - Method and apparatus for melting and purifying crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To melt and purify crystals efficiently by using a tower for melting and purifying crystals in an adductive crystals-forming system. SOLUTION: In a method for melting and purifying crystals, wherein raw liquid slurry is fed from one side of an upright tower 10, and the other side is allowed to be in a high-temperature range at higher temperature, and a crystal component of the raw material is transferred to the other side, and the transferred crystal component is allowed to be heated and melted in the high-temperature range, and a part of the molten solution is withdrawn as a product from the other side, and a remaining part is refluxed to the one side as reflux liquid, the same kind of solvent additive liquid as solvent of the raw liquid slurry is added to the high-temperature range, where an operating temperature is lower than the melting temperature of the crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Detailed description of the invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing purified bisphenol A. More specifically, the present invention relates to a method for chemically synthesizing phenol and acetone as raw materials in the presence of a strong acid or a strongly acidic ion exchange resin as a catalyst. Or not,
From a general reaction product produced by a transesterification reaction with diphenyl carbonate, water produced by the reaction and remaining acetone are removed by distillation, and the crude phenol solution of bisphenol A obtained is cooled, Or concentrate and conduct crystallization operation to obtain adduct crystals (molecular adducts)
The slurry is substantially completely separated from the mother liquor by a tower-type crystal refiner to obtain a purified phenol solution of bisphenol A, and the mother liquor containing isomers and other impurities is circulated to the reaction system process. Then, the pure bisphenol A and phenol mixture is supplied to a distillation column or the like, and phenol is substantially completely removed to obtain a very high-purity purified bisphenol A.

[0003]

2. Description of the Related Art Bisphenol A (2,2-bis (P-
Hydroxyphenyl) propane) is a raw material for synthesizing polycarbonate resins and epoxy resins. This bisphenol A is industrially produced on a large scale by a condensation reaction from 2 equivalents of phenol and 1 equivalent of acetone in the presence of a catalyst such as a strong acid or a strongly acidic ion exchange resin and, if necessary, a cocatalyst. I have. The crude bisphenol A thus obtained usually contains a considerable amount of impurities such as (o-, p-) isomers, linear and cyclic oligomers such as trimers, and impurities such as chromans. Therefore, conventionally, after being purified by a crystallization method or the like, it has been used as a raw material for the plastic production.

In purifying crude bisphenol A, there are typically the following two methods. That is, as a first method, first, in a distillation column, water, unreacted acetone, mercaptans as a reaction accelerator, and the like generated from the condensation reaction solution are removed from the condensation reaction solution, and then the isomers and high-boiling impurities are removed. The concentration of the phenol solution containing bisphenol A is adjusted by a concentration can or the like, and then supplied to a series of crystallization steps.

In the crystallizer in the crystallization step, the solution is cooled to crystallize an adduct crystal of bisphenol A and phenol, and the crystal is separated from the crystal slurry by a filter, a centrifuge, or the like. After the crystal cake is thoroughly washed with a pure phenol solution, the liquid component is separated again and dissolved by heating, and this heated solution is sent to the next second stage of purification and crystallization.

[0006] In the second stage of purification and crystallization, the heated solution is circulated using a separated mother liquor from the rear, etc., and after concentration adjustment,
This is the liquid to be supplied to the crystallizer. This is cooled to crystallize adduct crystals of bisphenol A and phenol.
Crystals are separated from the crystal slurry by a filter, a centrifuge, or the like, and the cake is washed, thereby completing the second-stage purification and crystallization step. After dissolution by heating, the crystal cake is sent to the next phenol removal step for phenol separation.
In the dephenolization step, phenol is completely separated,
It is to obtain highly purified purified bisphenol A by removal.

[0007] The second purification and crystallization method of crude bisphenol A involves a method in which a phenol solution containing an isomer or a high-boiling-point impurity and bisphenol A is concentrated by evaporating most of the phenol, and then introduced into a large amount of warm water. Then, cooling is performed to obtain bisphenol A (simple) crystals.

[0008] Bisphenol A has considerable solubility in phenol solutions, but hardly dissolves in warm water. Therefore, bisphenol A is crystallized by mixing a melt containing a small amount of phenol in a large amount of warm water.

[0010] In this method, crystals are separated from the crystal slurry by a filter, a centrifugal separator or the like, and the crystal cake is completely removed from the remaining phenol and water to obtain highly purified bisphenol A.

[0010]

However, in the above-mentioned method for purifying crude bisphenol A, the first method requires at least two crystallization steps. Further, in the second method, in order to separate and purify the purified bisphenol A, it is necessary to circulate a large amount of hot water in the process and a purification step of the hot water is required, and the process cannot be substantially simplified. Has problems and is not economical.

Generally, in a crystallization purification method, a crystal cake from which a target crystal is separated contains a certain amount of a mother liquor (contains a large amount of impurities), and actually, the crystal cake is formed by crystallization and solid-liquid separation. It is difficult to use only a single substance, and it is necessary to completely remove the mother liquor for high-purity commercialization.

However, efficiently in an industrially simple manner,
If the mother liquor content can be substantially reduced to zero, a separation and purification method can be constructed by very economical crystallization.

[0013] For this reason, if the countercurrent displacement washing is sufficiently performed using a tower-type crystal melting and refining tower, only a single crystal can be obtained by crystallization.

However, bisphenol A, which is the target substance, has a relatively high melting point as a pure product (about 158 ° C.) and becomes yellow-brown when exposed to a high temperature near the melting point for a long time. Discolored,
Thereafter, when the final product is obtained, coloring remains. As described above, bisphenol A is polymerized by a polymerization reaction and used as a raw material for a polycarbonate resin or an epoxy resin. Therefore, the color component reduces the transparency of the product,
Alternatively, since a resin having poor chromaticity loses its product value, a method of performing melting and refining using a general tower-type crystal melting and refining tower has not been adopted.

Therefore, an object of the present invention is to remarkably increase the purification efficiency and purity by using a column-type crystal melting and refining tower, and to obtain a product without coloring when the purification target substance is bisphenol A. It is in.

[0016]

According to the first aspect of the present invention, which solves the above-mentioned problems, a stock solution slurry is supplied from one side of a vertical column, and the other side is set to a high-temperature region having a higher temperature.
The crystal component of the raw material is moved to the other side, and the moved crystal component is heated and melted in the high-temperature region, and a part of the melt is supplied from the other side to a product (the “product” is an intermediate product and a final product). Including both cases)
In the method of melting and refining a crystal in which the remainder is refluxed to one side (countercurrent to the crystal) as a reflux liquid, a solvent (addition) liquid of the same kind as the solvent of the stock solution slurry is added to the high temperature region, A method for melting and refining a crystal, characterized in that the operating temperature in the region is lower than the melting point of the target crystal.

According to a second aspect of the present invention, there is provided the method for melting and refining a crystal according to the first aspect, wherein the solvent added component is removed from the product taken out of the vertical tower to produce the product.

According to a third aspect of the present invention, there is provided the method for melting and refining a crystal according to the first aspect, wherein the amount of the solvent addition liquid is controlled.

According to a fourth aspect of the present invention, the stock slurry is supplied from one side of the vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. Heating and melting the crystal component in the high temperature range,
In a method for refining crystals in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, the high temperature liquid is extracted from the inside of the other side and returned to the inside of the other side. Forming a circulation loop, heating and melting the crystal component by heating and raising the temperature in this external circulation loop, adding a solvent addition liquid of the same type as the solvent of the stock solution slurry into the external circulation loop, A melting and refining method for a crystal characterized by operating at a temperature lower than the melting point of the target crystal.

According to a fifth aspect of the present invention, an adduct crystal slurry of bisphenol A is supplied from one side of a vertical column,
The other side is a high temperature region where the temperature is higher, the crystal component of the crystal slurry is moved to the other side, and the moved crystal component is heated and melted in the high temperature region, and a part of the melt is made into a product from the other side. This is a method for melting and refining a crystal in which the remainder is refluxed to the one side as a reflux liquid, wherein a solvent addition liquid of the same kind as the solvent of the stock slurry is added to the high temperature area, and the operation temperature in the high temperature area is adjusted. A method for melting and refining high-purity bisphenol A crystals, characterized by operating at a temperature lower than the melting point of the crystals.

According to a sixth aspect of the present invention, the raw liquid slurry is supplied from one side of the vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. Heating and melting the crystal component in the high temperature range,
In a crystal melting and refining apparatus in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, a means for adding a solvent addition liquid of the same kind as the solvent of the stock solution slurry to the high temperature region Which is a melting and refining apparatus for crystals.

According to a seventh aspect of the present invention, the raw liquid slurry is supplied from one side of the vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. Heating and melting the crystal component in the high temperature range,
In a crystal melting and refining apparatus in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side, a high temperature liquid is extracted from the inside of the other side and returned to the inside of the other side. A circulation loop, a means for heating and melting the crystal component by heating and increasing the temperature in the outer circulation loop, and a means for adding a solvent addition liquid of the same kind as the solvent of the stock slurry in the outer circulation loop A method for melting and refining crystals.

[0023]

Next, the present invention will be described in more detail.

The melting point (melting point) of bisphenol A is about 158 ° C., and the melting point of phenol is 40.75.
The transition point of an intermolecular adduct (adduct) in which one molecule of bisphenol A and one molecule of phenol are associated is 98 ° C. The phase diagram of bisphenol A and phenol in crystallization is as shown in FIG.

[0025] Tower-type crystal melt refiners are known. In a conventional tower-type crystal melting and refining machine, without adding a third material solvent into the tower, for example, the crystals descending into the tower are heated and melted at the bottom, and the heated melt is raised. Then, the falling crystals are subjected to countercurrent cleaning. Therefore, in order to obtain a high-purity product, it is necessary to maintain the melting point or higher at the bottom of the column in order to heat and melt the crystal.

As for the melting and refining of the bisphenol A crystal, a high-temperature operation at a temperature of 158 ° C. or higher, which is the above-mentioned melting point, is required in the heat melting section.

However, as described above, in this operation,
In order to cause coloring, a tower-type crystal melting and refining machine could not be used. Various, though not conclusive, causes of this coloring have been considered. For example, a very small amount of impurities having an unsaturated bond contained therein can be polymerized at high temperatures and become tarred to form a color, or, due to the presence of oxygen, undergo an oxidation reaction to form a tar and become colored. Is assumed.

However, according to the present invention, when a solvent addition liquid of the same kind as the solvent of the stock slurry is added to a high-temperature region, for example, a heating and melting portion, and the operation temperature in the high-temperature region is lower than the melting point of the target crystal, A high-quality product (product) having substantially no color can be obtained using a tower-type crystal melting and refining machine.

On the other hand, the construction of a system that heats and melts at a temperature lower than the melting point of the crystal reduces the equipment load for keeping the heat of the crystal melting and refining machine and lowers the temperature of the heat medium for heating and melting. Accordingly, the required utility (energy) burden can be reduced, and in any case, the equipment cost and the operating cost can be reduced.

The present invention is an organically combined operation of operating the heat-melting section at a temperature lower than the melting point of the target crystal and adding a solvent addition liquid of the same kind as the solvent of the stock slurry. . Taking this as an example using bisphenol A that crystallizes adduct crystals, and referring to the phase diagram of FIG. 1, the eutectic temperature (eutectic point) of bisphenol A and phenol in an adduct mother liquor is 98 ° C. In this system, the eutectic mixture is present at 1: 1 molar at this temperature. In this system, the point of 1: 1 molar between the crystalline solid bisphenol A and phenol is 58.0 as the bisphenol A concentration as shown in the figure. % To 70.8%. As a result, when the heating and melting part is operated at around 98 ° C., single crystals that are not adducts of bisphenol A are generated, and these crystals are sequentially deposited in the heating and melting part, which hinders operation.

However, according to the present invention, when a solvent addition liquid of the same kind as the solvent of the stock solution slurry is added to the heated and melted portion, the adduct crystal is decomposed by phenol in this case, and crystallization is attempted. Bisphenol A crystals can be dissolved, whereby crystallization of bisphenol A can be prevented, and the operation is not hindered due to the sequential deposition of crystals in the heated and melted portion.

FIG. 2 shows an overall production flow of bisphenol A, and FIG. 3 shows an example of a crystal melting and refining machine.
This will be described sequentially.

In FIG. 2, as described above, for example,
In reaction step 1, phenol and acetone are used as raw materials, and are synthesized by a condensation reaction in the presence of a strong acid or strongly acidic ion exchange resin catalyst and a cocatalyst. In this case, phenol is supplied to the reactor in an equivalent amount as compared with acetone for the purpose of effectively removing heat of reaction and suppressing the formation of isomers.

Next, generally, from this reaction product,
Water generated by the condensation reaction, remaining acetone and cocatalyst are removed by distillation in distillation step 2, and the obtained phenol solution of crude bisphenol A is subjected to concentration adjustment using a concentrator or the like, and then to crystallization step 3. Supply.

In the crystallizer in the crystallization step 3, about 98
The crystallization is carried out in a temperature range of up to 35 ° C., but economically, it is desirable to cool down to as low a temperature as possible to recover bisphenol A as much as possible, preferably 40 to 60 ° C.
To obtain an adduct crystal of bisphenol A as shown in the phase diagram of FIG.

Conventionally, crystals are separated from the crystal slurry by a filter, a centrifugal separator, etc., and the crystal cake is thoroughly washed with phenol, separated again, heated and dissolved, and isomers and other impurities are removed. Is returned and circulated to the reaction system process. The heat-dissolved solution of the crystals is sent to the next second-stage purification crystallization step, where the heat-dissolved solution is similarly adjusted in concentration with a circulating mother liquor from the back, cooled, and bisphenol is added in the same manner as in the previous step. A and phenol adduct crystals are crystallized, and the crystals are separated from this crystal slurry using a filter or centrifuge,
After the cake washing, the second-stage purification crystallization step is completed. After dissolution by heating, the crystal cake is sent to the next phenol removal step for phenol separation.

In the present invention, however, the process is led to a melting and refining step 4, where the crystal is melt-refined to obtain a highly purified melt of the adduct crystal, and the phenol contained in the melt is removed. Removed in phenol step 5. The product from which phenol has been removed may be used as a product as it is or may be made into a granular solid through a granulation step 6.

An example of the melting and refining machine 10 is shown in FIG. 3 and is of a vertical tower type, equipped with a heat retaining trace 12 and the like, and a heating and melting section 14 for flowing a heat medium below.
It has. As a result of the high-temperature liquid generated by the heating and melting unit 14 flowing back through the melt purifier 10, a temperature gradient is formed in the melt purifier 10. A stirrer 16 having stirring blades 16a is provided above the heating and melting unit 14, and the crystal packed bed is slowly stirred by a stirring drive motor 16b.

The adduct crystal slurry of bisphenol A from the crystallization step 3 is supplied as a raw material from the upper part of the melt refiner 10. The crystals in the crystal slurry settle and move downward due to gravity, and eventually reach the heating and melting unit 14.
The crystals are melted in the heating and melting section 14 and a part is extracted from the lower part as a product and supplied to a downstream process as shown in FIG. The remaining melt rises and passes through the gaps in the crystal bed, displacing the crystals pushed down. Thus, the descending crystal and the refluxing melt are brought into countercurrent contact, and the crystal particles descending (or pushed downward) by the refluxing melt are sufficiently washed to obtain a high-purity crystal. In such a melting and refining process, the crystals are exposed to a high temperature before melting, so that a sweating phenomenon occurs and the purity is remarkably increased.

Thus, by performing the melting and refining operation of the crystal in the melting and refining machine 10, a very pure melt product can be obtained in one step.

In the case of melting and refining bisphenol A crystals, the heating and melting section 14 is heated to a temperature of about 98 ° C.,
It is preferable to operate at 8 ° C. ± 2 ° C., more preferably at 98 ° C. ± 1 ° C. with accurate temperature control. Melt refiner 1
The temperature gradient within 0 can be appropriately selected.
It can be a temperature of ８５85 ° C.

On the other hand, as shown in FIG. 3, fail is added to the heating and melting section 14 as a solvent addition liquid of the present invention. The position of this addition is desirably within the height range of the heating and melting portion 14. If the position is higher (or separated) than the heated and melted portion 14, the bisphenol A crystals tend to deposit without being dissolved. Further, since the product is withdrawn from the bottom of the column, if added to this position, phenol will be mixed into the melt of bisphenol A and will flow out as it is, so it is desirable to avoid such addition.

The added amount of the solvent, in this case, phenol, is an amount sufficient to dissolve the bisphenol A crystals. Although the temperature of the phenol to be added is preferably about 98 ° C. ± 1 ° C., it can be appropriately selected from the range of 50 ° C. to 98 ° C. if a sufficient amount is added. It is also possible to add at a temperature of 98 ° C. or higher. When added at a temperature of 98 ° C. or higher, the amount of the heat medium supplied to the heating and melting unit 14 can be reduced. Furthermore, it is possible to control to increase or decrease the amount of phenol to be added over time in the course of crystal refining, for example, based on observation of the properties of the product. By increasing or decreasing the amount of phenol added, it is possible to control the temperature of the heating and melting section 14 and also control the temperature gradient in the tower.

In addition to the phenol addition, it can be added continuously or intermittently or batchwise.

For the heating and melting portion, an appropriate heat transfer medium means can be used. As an example of this, there is an electric heater, and preferably, a heat transfer heating tube, particularly shown in Japanese Patent Application Laid-Open No. 9-85008 proposed by the present applicant, and shown in FIG. It is desirable that a group of heat transfer heating tubes 14A, 14A... In this case, the heating medium 20 is at the inlet 2
After passing through the inner tube 14a, it is supplied from the outer tube 14a and then flows out of the outlet 22 through the space between the outer tube 14b and the outer tube 14b. 23 is a crystal separation screen.

In the present invention, from one side of the vertical tower,
As in the above example, in addition to the upper portion, the undiluted slurry is supplied from the lower portion, the other side is set to a high temperature region where the temperature is higher, the crystal component of the raw material is moved to the other side, and the moved crystal component is transferred to the high temperature region. In the melting and refining apparatus of the crystal, a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid. It can be adopted as appropriate.

The inside of the vertical column has a portion filled with crystal grains, and this crystal packed layer may be a close packing or a loose packing with a slight flow. In addition to a device provided with a transfer means such as a screw conveyor for moving the crystal bed (for example, Japanese Patent Application Laid-Open No. 9-85008), the stirrer shown in FIG. You may have. What does not have a screw conveyor or a stirrer inside may be used. The crystal filling part may be in a so-called irrigation state in addition to a so-called full state.

The heat-melting section may be provided at the bottom of the column, depending on the target substance, in addition to being provided at the bottom of the column as shown in the above-described embodiment. The crystal melting slurry and the melt may be circulated inside and outside the melting and refining tower by holding the heating and melting unit outside the melting and refining tower, instead of inside. Further, a cooling crystallization section may be provided inside the tower, and the cooling crystallization section may be connected to the melting and refining section.

The existence of various types or operation modes of this type of melt purification column is described in "Aromatics" No. 37.
Vol., No. 7.8 (1985), pp. 109-127.

On the other hand, the embodiment shown in FIG. 6 can also be adopted. That is, a pump 30 for extracting a high-temperature liquid from the inside thereof and returning it to the original inside thereof is also provided at the lower portion of the melt refining machine 10 to form an external circulation loop 32. In the external circulation loop 32, a steam in the heat exchanger 31 and the like is formed. Is added and heated to raise the temperature, thereby heating and melting the crystal component.

In this case, a solvent addition liquid of the same kind as the solvent of the stock slurry, for example, phenol, can be added from the addition line 33 into the external circulation loop 32.

In this case, since the heating and melting section is not formed inside the lower portion of the melt refining machine 10, in order to loosen the packed layer of crystals, for example, a scraping means 3 driven by a motor is used.
4 is desirably provided.

Also in this example, the operation temperature of the high-temperature region (the inside of the lower part of the melt refining machine 10 and the heat exchanger 31) is operated at a temperature lower than the melting point of the target crystal.

[0054]

EXAMPLES Next, the effects of the present invention will be described with reference to examples.
Bisphenol A was obtained according to the flow of FIG. That is,
From the product liquid after the condensation reaction, water, acetone,
Light boiling components such as mercaptan were removed. This liquid composition is
BPA (bisphenol A) = 18.0% by weight (% is% by weight unless otherwise noted), isomer = 0.9
%, Other impurities = 1.2%.

This was concentrated until the BPA became about 30%, or the concentration was adjusted with a recycle liquid, and the concentration was adjusted to about 95%.
After adjusting to a molten state at ℃, indirect cooling or adiabatic cooling to a temperature of 45 ℃ in the crystal can to crystallize adduct crystals.

The produced crystal slurry has a crystal concentration of 20 to 35 watts from the viewpoint of transportation, handling, and economy.
The crystal slurry was supplied to a crystal melting and refining tower shown in FIG. The melting and refining tower used was 10
0 mmφ × 1000 mmH.

The temperature of the heating and melting part is 98 ° C. ± 1 ° C.
In addition, phenol was added at 98 ° C. ± 1 ° C. As a result, 11 liters of bisphenol A product (phenol solution) per hour could be obtained. The maslow in this case is shown in FIG. The purity of the product was much higher than expected and no color was observed.

[0058]

As described above, according to the present invention, the purification efficiency and the purity are remarkably increased by using a tower-type crystal melting and refining tower. There are advantages such as being able to be none.

[Brief description of the drawings]

FIG. 1 is a phase diagram.

FIG. 2 is a flow chart showing an example of a production process of bisphenol A.

FIG. 3 is a schematic diagram illustrating an example of a crystal refining tower.

FIG. 4 is a partial explanatory view of an example of a heating and melting unit.

FIG. 5 is an explanatory diagram of a mass flow of an example of bisphenol A.

FIG. 6 is a schematic view of a crystal melting and refining tower according to another example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reaction process, 2 ... Distillation process, 3 ... Crystallization process, 4 ... Melt purification process, 5 ... Dephenolization process, 6 ... Granulation process, 10
... Melt refining machine (melt refining tower), 14.

[Procedure amendment]

[Submission date] December 4, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (7)

[Claims] 1. An undiluted slurry is supplied from one side of a vertical tower, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. In the method of melting and refining a crystal in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, the same kind of solvent as the stock slurry is used for the high temperature region. A method for melting and refining a crystal, comprising adding the solvent addition liquid of (1) and operating at an operating temperature in the high temperature range lower than the melting point of the target crystal. 2. The method for melting and refining crystals according to claim 1, wherein said solvent added liquid is removed from the product taken out of said vertical column to produce a product. 3. The method according to claim 1, wherein the amount of the solvent addition liquid is controlled. 4. A raw liquid slurry is supplied from one side of a vertical tower, and the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. In a method for melting and refining a crystal in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, a high-temperature liquid is extracted from the inside of the other side and An external circulation loop is formed to return to the inside, and heating and melting are performed in this external circulation loop to increase the temperature of the crystal component, and a solvent addition liquid of the same kind as the solvent of the stock solution is added to the external circulation loop. A method for melting and refining a crystal, wherein the operation temperature in the high temperature range is lower than the melting point of the target crystal. 5. An adduct crystal slurry of bisphenol A is supplied from one side of a vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the crystal slurry is moved to the other side. A method for melting and refining a crystal in which components are heated and melted in the high-temperature range, a part of the melt is taken out as a product from the other side, and the remainder is refluxed to the one side as a reflux liquid. A method for melting and refining high-purity bisphenol A crystals, characterized by adding a solvent addition liquid of the same kind as the solvent of the stock slurry and operating the high-temperature region at a temperature lower than the melting point of the target crystals. 6. A raw liquid slurry is supplied from one side of a vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. In a crystal melting and refining apparatus in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, a solvent of the same kind as the solvent of the stock slurry for the high temperature region An apparatus for melting and refining crystals, comprising means for adding an additive liquid. 7. An undiluted slurry is supplied from one side of a vertical column, the other side is set to a high temperature region where the temperature is higher, and the crystal component of the raw material is moved to the other side. In a crystal melting and refining apparatus in which a part of the melt is taken out as a product from the other side and the remainder is refluxed to the one side as a reflux liquid, a high-temperature liquid is extracted from the inside of the other side and An external circulation loop for returning to the inside of the device, a means for heating and melting the crystal component by heating and increasing the temperature in the external circulation loop, and a solvent addition liquid of the same kind as the solvent of the stock slurry in the external circulation loop. A method for melting and refining crystals.