TWI539986B - A slurry regeneration device, a slurry regeneration method and a regeneration slurry - Google Patents

Description

Slurry regeneration device, slurry regeneration method and regeneration slurry

The present invention relates to a slurry used for cutting an ingot such as a wire saw by a wire saw, a slurry regenerating device which can be reused by removing the chips from the slurry, a slurry regenerating method, and a slurry regenerating method Regenerated regeneration slurry.

The crucible wafer used in a solar cell or the like is obtained by cutting a silicon ingot into pieces (slices) using a wire saw. In the method of cutting the crucible ingot, there are a fixed abrasive method and a free abrasive method. In the fixed abrasive method, a wire saw with abrasive grains such as diamonds and a slurry containing a coolant (coolant) are used to cut the bismuth ingot. In addition, in the free abrasive mode, a wire saw is used. The bismuth ingot is cut with a slurry containing abrasive particles such as a coolant and a tantalum carbide. In either case, a predetermined amount of slurry is supplied to a portion (cutting portion) where the wire saw cuts the bismuth ingot. The slurry is used to perform cutting. The cooling of the part and the discharge of the chips (cutting chips) from the cutting portion. The slice cut in this way adheres to the slurry or the chips, etc. Therefore, after the cutting step, the slice is washed to obtain the silicon wafer.

In general, the slurry (used slurry) used in the cutting step of the bismuth ingot is reused from the viewpoint of manufacturing cost. This used slurry contains swarf chips (hereinafter, simply referred to as "chips".) , abrasive particles (in the case of cutting by means of free abrasive), and the like. Therefore, if the used slurry is directly reused, it may cause damage to the surface of the wafer, damage to the wafer, deterioration of the cutting mechanism, and the like. Therefore, the chips and the like are removed from the used slurry by, for example, the slurry regeneration method described in Patent Document 1. In the slurry regeneration method, chips or the like are removed from the used slurry by a so-called horizontal centrifugal separator. Thereby, a reusable slurry (regenerated slurry) can be obtained. In the horizontal type centrifugal separator, the used slurry is rotated by rotating the central axis toward the horizontal direction, and the used slurry is rotated by the central axis as a center of rotation, and the chips or abrasive grains are separated from the used slurry by the centrifugal force. . The regenerated slurry obtained in this manner (the slurry obtained by separating the chips or the abrasive grains by centrifugation) can be reused.

However, in the case where the regenerated slurry obtained by the above method is reused, the viscosity of the regenerated slurry may be greatly increased. When the viscosity of the regenerated slurry is increased, the piping resistance at the time of supplying the regenerated slurry to the cutting portion is increased, and the amount of slurry supplied to the dicing portion is changed, or the chip discharge property at the dicing portion is deteriorated. In addition, when such a regenerated slurry is used, the cleaning step after the cutting step may deteriorate the cleaning property (that is, the adhering matter such as the regenerated slurry adhered to the slice may be difficult to remove).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-353660

An object of the present invention is to provide a slurry regenerating apparatus and a slurry regenerating method for regenerating a used slurry, thereby suppressing an increase in viscosity and obtaining a regenerated slurry which suppresses deterioration of cleaning performance in a washing step after ingot cutting. Further, another object of the present invention is to provide a regenerated slurry obtained by the slurry regeneration method.

As a result of intensive research, the inventors of the present invention found that when the amount of iron (iron, iron ions, iron oxide, etc.) contained in the regenerated slurry increases, the viscosity of the regenerated slurry rises or the ingot is cut. Deterioration of cleaning performance in the cleaning step. The details are as follows.

In the cutting step of the ingot, the wire saw cutting causes iron (iron powder, iron particles) from the wire saw to be mixed into the regenerated slurry. Therefore, as the ingot block is cut, the amount of iron in the regenerated slurry will continue to increase. Since the iron mixed in the regenerated slurry is a fine powder, it is easily dissolved into iron ions by the moisture contained in the regenerated slurry. Further, a part of the iron mixed in the regenerated slurry is oxidized by exposure to air and becomes iron oxide. Therefore, in the recycled slurry in use, the iron content will continue to increase. This iron fraction is believed to be mainly present in the regenerated slurry with iron ions.

After the regenerated slurry has been used for a certain period of time, it is discharged from the ingot slicing device or the like in the form of the used slurry, and the chips are removed by the horizontal centrifugal separator and reused. At this time, a part of the iron (iron powder, iron particle) particles is removed from the iron fraction of the used slurry. However, iron ions, which account for more than half of the iron fraction, are not removed by the horizontal centrifugal separator. Therefore, the regenerated slurry obtained by removing chips or the like may contain a large amount of iron.

Secondly, after the recycled slurry containing many iron fractions is used, That is, when the iron content contained in the regenerated slurry is further increased, the viscosity of the regenerated slurry is increased, or the cleaning property in the cleaning step after the ingot is cut is deteriorated.

The state of the present invention is a slurry regenerating apparatus which can regenerate the used slurry containing the chips generated when the ingot is cut by a wire saw in a recyclable manner. The slurry regenerating apparatus includes an air supply unit that supplies air to the used slurry, and a centrifugal separation unit that centrifugally separates the used slurry supplied with air from the air supply unit.

Further, another aspect of the present invention is a slurry regeneration method which can regenerate a used slurry containing chips generated by cutting a block using a wire saw in a recyclable manner. The slurry regeneration method is to supply air to the aforementioned used slurry, and centrifugally separate the used slurry supplied through the air.

10‧‧‧Slurry regeneration device

10A‧‧‧Regeneration device

10B‧‧‧Regeneration device

11‧‧‧Abrasive Grain Recycling Department

13‧‧‧Isolation Department for Iron Separation

14‧‧‧Separation centrifuge for iron separation

15‧‧‧ Membrane Separation Department

16‧‧‧Component Adjustment Department

110‧‧‧Abrasive grain recovery storage

111‧‧‧Recycling storage tank

112‧‧‧Recycling mixer

113‧‧‧Agitating wing

114‧‧‧Rotary axis

115‧‧‧Motor

120‧‧‧Recycling Centrifuge

122‧‧‧ rotating body

124‧‧‧Separate discharge

125‧‧‧Export

130‧‧‧Separation storage tank

131‧‧‧Separator Mixer

132‧‧‧Agitator wing

133‧‧‧Rotary axis

134‧‧‧ motor

135‧‧ Air Supply Department

136‧‧‧Air supply pipe

140‧‧‧Waste storage tank

150‧‧‧ hollow fiber membrane

151‧‧‧Shell

160‧‧‧Adjustment storage tank

161‧‧‧Recycling Supply Division

162‧‧‧Component Supplement

A‧‧‧Used slurry

B‧‧‧Used slurry after a centrifugal separation

C‧‧‧Used slurry after secondary centrifugation

D‧‧‧Three times of centrifugal separation + used slurry after membrane separation

E‧‧‧Separation after centrifugation

F‧‧‧Separators after secondary centrifugation

G‧‧‧Separators after three centrifugation

H‧‧‧ Regenerated slurry

Fig. 1 is a schematic configuration diagram of a slurry regenerating apparatus according to the embodiment.

Fig. 2 is a view showing a slurry regenerating step of the slurry regenerating apparatus and an example of material balance after each step.

Fig. 3 is a schematic configuration diagram of a slurry regenerating apparatus according to another embodiment.

Fig. 4 is a schematic configuration diagram of a slurry regenerating apparatus according to still another embodiment.

[Formation of the Invention]

Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 and 2 . Fig. 1 is a schematic configuration diagram of a slurry regenerating apparatus according to the embodiment. Fig. 2 is a view showing a slurry regeneration step of the slurry regenerating apparatus and a material balance diagram after each step.

The slurry regenerating apparatus (hereinafter, simply referred to as "regeneration apparatus") 10 of the present embodiment is used for cutting a tantalum ingot by a wire saw in a manufacturing process of a tantalum wafer such as a semiconductor or a solar cell (hereinafter, The slurry used in the case of "ingot only" is also subjected to regeneration (regeneration treatment). In other words, the regenerative device 10 separates (removes) the mixed matter such as chopped chips (hereinafter, simply referred to as "chips") from the used slurry, so that the coolant can be reused. Further, although the bismuth ingot cutting method in the present embodiment is a free abrasive method, it may be a fixed abrasive method.

Hereinafter, the slurry (used slurry and regenerated slurry) will be described first, and then the regeneration device 10 will be specifically described.

The slurry contains a coolant and a plurality of abrasive particles. The slurry is supplied to the wire saw cutting portion of the ingot in the cutting step of the ingot, and the cooling of the cutting portion and the chip discharge of the cutting portion are performed. Hereinafter, the slurry which has been used for the ingot block cutting is referred to as the used slurry, and the slurry which has been subjected to the regeneration treatment by the regeneration device 10 (separating the mixed materials such as chips from the used slurry, etc.) is referred to as a regenerated slurry. .

In addition to the coolant and most of the abrasive grains, the regenerated slurry also contains a small amount of chips and irons generated when the ingot is cut by a wire saw. The iron component is iron (iron powder, iron particles), iron ions (Fe ²⁺ , Fe ³⁺ ), iron oxide (for example, Fe ₂ O _{3 ,} etc.) derived from a wire saw generated by cutting a wire saw or the like. .

The iron concentration of the regenerated slurry is 1000 ppm or less. The iron concentration of the regenerated slurry can be obtained as follows. For example, a sample obtained by dissolving nitric acid and hydrofluoric acid in a partially regenerated slurry and heat-treating may be used to dissolve particles such as iron or iron oxide contained in the regenerated slurry. Then, the sample was analyzed by ICP (Inductively Coupled Plasma). By this method, the iron concentration in the regenerated slurry can be obtained. Further, the method of measuring the iron component concentration is not limited to the above-described measurement method. Other known methods of measurement can also be used.

The coolant is mainly composed of a water-soluble solvent such as polyethylene glycol. In particular, the coolant is formed by, for example, polyethylene glycol alone or in a polyethylene glycol, water, a pH adjuster, a viscosity modifier, a dispersant, an aggregating agent, or the like as a combination of additives. Further, the coolant is mainly composed of divinyl alcohol as a main component, and an additive such as water, a pH adjuster, a viscosity adjuster, a dispersant, or a coagulant is added thereto. The viscosity of the coolant is about 10 to 15 cp.

Further, in the case where the coolant is diluted with water, various additives may be added. Therefore, the composition and viscosity of the coolant are not limited to the above composition. That is, the coolant may be a slurry which can be used when the wire saw cuts the ingot, and may have other compositions or viscosities.

The abrasive grains are particles such as lanthanum carbide (SiC), and have an average particle diameter of, for example, 8 to 15 μm. Further, the abrasive grains may be particles of other materials as long as they can be used to cut the ingots by a free abrasive.

The iron contained in the regenerated slurry is iron (iron powder, iron particles) generated from a wire saw due to friction or the like when the ingot is cut by a wire saw. This iron is dissolved by water (moisture) contained in the coolant to become iron ions (Fe ²⁺ , Fe ³⁺ ). Then, the iron ions are oxidized to iron oxide as time passes. Therefore, the regenerated slurry contains iron ions and iron oxide in addition to iron. Further, since the used slurry has been used for the slurry produced after the ingot is cut, it also contains iron, iron ions, iron oxide, and the like.

The regeneration device 10 includes an abrasive grain collection unit 11 , an iron separation storage unit 13 , an iron separation centrifugal separator 14 , a membrane separation unit 15 , and a component adjustment unit 16 . The regenerating apparatus 10 regenerates the used slurry by reusable by separating the mixed matter such as chips from the used slurry.

The abrasive grain collecting unit 11 includes an abrasive grain collecting storage unit 110 and a collecting unit centrifugal separator 120. The main purpose is to recover the abrasive particles from the used slurry.

The abrasive grain recovery storage unit 110 includes a recovery unit storage tank 111 and a recovery unit mixer 112. The recovery portion storage tank 111 is for storing the used slurry discharged from the ingot cutting device or the like. The collecting unit mixer 112 includes a stirring blade 113 disposed in the collecting portion storage tank 111 and a motor 115 having a rotating shaft 114 to which the stirring blade 113 is connected. The agitating blade 113 is rotated by the motor 115 to agitate the used slurry in the recovery portion storage tank 111.

The collection unit centrifugal separator 120 is a horizontal centrifugal separator that rotates the object to be separated (in the present embodiment, the used slurry is used as a center, for example, a horizontal or substantially horizontal rotation axis). . The recycling section centrifugal separator 120 has a rotating body 122 The first motor, the abbreviated auger, and the second motor, which are omitted from the drawings, are omitted. The rotating body 122 has a tubular shape in which a tapered portion is formed on one end side, and is rotatable about a central axis (horizontal axis) in the horizontal direction as a center of rotation. The first motor (not shown) rotates the rotating body 122 about the central axis. The auger illustrated in the figure is disposed inside the rotating body 122 so as to be coaxial with the rotating body 122. The second motor (not shown) rotates the auger illustrated in the figure so as to slightly rotate the rotation of the rotating body 122 during rotation.

In the collection unit centrifugal separator 120, the used slurry is introduced into the inside of the rotating body 122. Solid components such as chips introduced into the used slurry in the inside of the rotating body 122 are pushed by the centrifugal force to the inner surface of the rotating body 122. The solid component moves toward the left side of FIG. 1 by the action of the auger, and the mixed matter or the like (abrasive grains and coolant) is centrifugally separated. The separated mixed matter or the like is discharged from the separator discharge port 124 to the component adjusting portion 16. On the other hand, the used coolant (separation liquid) which has been centrifuged and the like is discharged from the take-out port 125, and is returned to the recovery portion storage tank 111.

In the collection unit centrifugal separator 120, in order to remove (recover) the abrasive grains having a large particle diameter and a large specific gravity from the used slurry, the gravity is accelerated at a low gravitational acceleration (500 to 1000 G in the present embodiment). Centrifugal separation.

The iron separation storage unit 13 includes a separation unit storage tank 130, a separation unit mixer 131, and an air supply unit 135. In the storage portion 13, air is supplied to the used slurry stored in the separation portion storage tank 130. The separation portion storage tank 130 is supplied once from the recovery portion storage tank 111. The used slurry after centrifugation is stored. The separator mixer 131 has a stirring blade 132 disposed in the separation portion storage tank 130, and a motor 134 having a rotation shaft 133 to which the stirring blade 132 is connected. The agitating blade 132 is rotated by the motor 134, and the used slurry in the separation portion storage tank 130 is stirred. The air supply unit 135 supplies the air sent from the pump or the like (not shown) to the used slurry in the separation unit storage tank 130 through the air supply pipe 136. That is, the air supply unit 135 inflates the used slurry stored in the separation unit storage tank 130.

The configuration of the centrifugal separator 14 for iron separation is the same as the configuration of the centrifugal separator 120 of the recovery unit. In the centrifugal separator 14 for iron separation, the used slurry after centrifugation is discharged from the take-out port 125 and returned to the separation portion storage tank 130, and the separated mixed matter or the like is discharged from the separation discharge port 124. Go to the waste storage tank 140. In the centrifugal separator 14 for iron separation, secondary centrifugation and tertiary centrifugation are performed. The secondary centrifugal separation is performed by centrifugal separation using a high gravitational acceleration (2000 to 3000 G in the present embodiment) in order to remove the chips dispersed in the used slurry as much as possible. The three-stage centrifugal separation is centrifugal separation performed simultaneously with the membrane separation of the membrane separation unit 15 to be described later, and similarly to the secondary centrifugal separation, centrifugation using a high gravitational acceleration (2000 to 3000 G in the present embodiment) Separation.

The membrane separation unit 15 separates the mixed matter such as chips or iron from the used slurry by using a filtration membrane. The membrane separation unit 15 of the present embodiment includes a membrane module having a plurality of hollow fiber membranes 150 and a casing 151 for accommodating the plurality of hollow fiber membranes 150 in a bundled state. Further, the membrane separation unit 15 includes a pump, a pipe, and the like which are not shown. Design by this The used slurry can be introduced into the membrane separation unit 15 from the separation unit storage tank 130, and the used slurry after permeating the membrane can be introduced into the component adjustment unit 16, and the permeate liquid (chip or iron powder, etc.) can be used. The concentrated used slurry) is returned to the separation section storage tank 130. In addition, in FIG. 1, the bundle of the hollow fiber membranes 150 is shown in a schematic manner.

The molecular weight cut off of the hollow fiber membrane 150 is, for example, 13,000, and the membrane pore diameter (the pore diameter formed on the peripheral wall of the hollow fiber membrane) is, for example, 0.003 μm. Further, the molecular weight cut-off and the pore diameter of the hollow fiber membrane 150 are not limited to these values, and may be other values as long as they can remove the iron component contained in the used slurry. Further, the membrane separation in the membrane separation unit 15 is not limited to the filtration using the hollow fiber membrane 150, and may be other types of filtration.

The component adjusting unit 16 is configured to adjust the components so that the used slurry component after the membrane separation becomes a desired regenerated slurry component (composition). The component adjustment unit 16 includes an adjustment storage tank 160, a collection component supply unit 161, a component detection unit (not shown), a component addition unit 162, and a stirrer (not shown).

The adjustment storage tank 160 stores the used slurry which has been subjected to membrane separation by the membrane separation unit 15. The recovered component supply unit 161 supplies the separated matter (coolant and abrasive grains) separated in the collection unit centrifugal separator 120 to the adjustment storage tank 160. The component replenishing portion 162 supplies the new coolant and the new abrasive grains to the slurry (the used slurry after the membrane separation) in the adjustment storage tank 160 to obtain a regenerated coolant having a desired composition (component). . The supply amount of the new coolant and the abrasive particles may be set in advance, or the used film separated in the adjustment storage tank 160 may be detected first. The slurry component can be determined based on the detected value. The agitator omitted from the drawing has the same configuration as the recovery unit agitator 112 of the abrasive grain recovery storage unit 110, and agitates the slurry (regenerated slurry) in the adjustment storage tank 160.

In this regenerating apparatus 10, the used slurry is subjected to a regeneration treatment (i.e., a regenerated slurry is obtained from the used slurry) in the following manner.

The used slurry to be discharged, which is discharged from the ingot cutting device or the like, is first injected into the recovery portion storage tank 111 of the regeneration device 10. The material balance of the used slurry injected into the recovery portion storage tank 111 is, for example, 50 for the coolant, 50 for the abrasive grains, 4.5 for the chips (Si chips), and 0.75 for the iron (refer to A of FIG. 1). And A) of Figure 2. In the material balance, the chips and the iron were expressed in parts by weight with respect to 100, and the sum of the value of the coolant expressed by weight % and the value of the abrasive grains expressed by weight % was 100. Further, the used slurry injected into the recovery portion storage tank 111 includes iron (iron powder, iron particles) mixed when the ingot is cut by a wire saw, iron ions generated by the dissolution of the iron, and oxidation of the iron ions. After (after combining with oxygen) iron oxide.

When the used slurry is injected into the recovery section storage tank 111, in the abrasive grain collection storage unit 110, the recovery section mixer 112 starts agitation of the used slurry. Then, the used slurry is introduced from the recovery section storage tank 111 to the collection section centrifugal separator 120, and centrifugal separation is performed once. Next, the used slurry discharged from the collection unit centrifugal separator 120 once after centrifugation is returned to the recovery unit storage tank 111. In this manner, the used slurry is between the recovery section storage tank 111 and the recovery section centrifugal separator 120. After circulating for a certain period of time, the used slurry stored in the recovery portion storage tank 111 is injected into the separation portion storage tank 130 (see B of FIG. 1 and B of FIG. 2).

On the other hand, the separated mixture or the like (abrasive grains and coolant) is discharged from the separation outlet 124 to the component adjustment unit 16 by the collection unit centrifugal separator 120 (see E of FIG. 1 and FIG. 2). E).

When the used slurry which has been subjected to centrifugation once is injected into the separation portion storage tank 130, in the iron separation storage portion 13, the air supply portion 135 starts supplying air to the used slurry, and at the same time, the separation portion agitator 131 Start stirring the used slurry. By this process, the proportion of iron oxide contained in the slurry which has been used in the slurry is increased. The details are as follows.

When air is supplied to the used slurry, the iron and iron ions in the iron are oxidized to become iron oxide having a larger particle size than the iron (iron powder, iron particles) or iron ions. That is, when the used slurry is blown, the oxygen in the supply air combines with the iron ions to become iron oxide. Further, iron is dissolved in iron ions due to moisture contained in the slurry, and then combined with oxygen in the air to form iron oxide. At this time, since the supplied air is distributed to the entire used slurry stored in the separation portion storage tank 130 by the agitation of the separation portion agitator 131, the oxidation of iron is efficiently performed. In this way, the proportion of iron oxide in the iron fraction (iron, iron ions, iron oxide) increases.

After the iron supply and storage unit 13 starts the air supply and the stirring for a predetermined period of time, the used slurry is introduced from the iron separation storage unit 13 to the iron separation centrifugal separator 14 for secondary centrifugal separation. . Then, the used slurry which has been subjected to the secondary centrifugation discharged from the centrifugal separator 14 for iron separation is returned to the separation portion storage tank 130. In this manner, the used slurry is circulated between the separation portion storage tank 130 and the iron separation centrifugal separator 14 for a certain period of time. At this time, in the iron separation storage unit 13, the air supply unit 135 may continuously supply air to the used slurry; or, the used slurry may be supplied from the iron separation storage unit 13 to the iron. When the centrifugal separator 14 is separated, the supply of air is stopped. At the same time, the separated substances (abrasive grains and coolant) separated by secondary centrifugation are discharged from the separator discharge port 124 to the waste liquid storage tank 140 (refer to F of FIG. 1 and F of FIG. 2).

The centrifugally separated and the second centrifugally separated used slurry (that is, the used slurry stored in the separation portion storage tank 130 after the second centrifugal separation) is subjected to the above-described manner, and the abrasive grains are completely (or almost All) removed (refer to C of FIG. 1 and C of FIG. 2). Further, since the proportion of iron oxide in the iron fraction of the used slurry is increased by the pumping of the iron portion separation storage portion 13, a large amount of iron is used in the used slurry after the second centrifugal separation. Has been removed (refer to C of Figure 2).

Next, in the iron separation storage unit 13, the used slurry after the secondary centrifugation is simultaneously subjected to three centrifugation and membrane separation (membrane filtration). That is, the circulation of the used slurry between the separation portion storage tank 130 and the iron separation centrifugal separator 14 and the circulation of the used slurry between the separation portion storage tank 130 and the membrane separation portion 15 are simultaneously performed. . The former is performed by supplying the used slurry from the separation portion storage tank 130 in which the used slurry having been subjected to secondary centrifugation is stored to the centrifugal separator 14 for iron separation. Used pulp after centrifugation in the centrifuge 14 The liquid is returned to the separation portion storage tank 130. The latter is performed by supplying the used slurry from the separation portion storage tank 130 to the membrane separation portion 15. The permeated liquid discharged from the membrane separation unit 15 (the used slurry after the concentrated iron oxide or the like which has been removed by the clean slurry of the filtration membrane) is returned to the separation unit storage tank 130. The mixture or the like (coolant or the like) separated by the three centrifugation is discharged from the separator discharge port 124 to the waste liquid storage tank 140 (see G of FIG. 1 and G of FIG. 2).

The iron fraction and the chips remaining in the used slurry after the second centrifugation are completely (or almost completely) removed by membrane separation simultaneously with the three centrifugation. That is, the particle size (for example, about 0.005 to 0.05 μm) of iron (iron powder, iron particles) contained in the slurry has been used, and since the particle diameter is smaller than that of the abrasive grains, the second centrifugal separation is performed. Iron has been left in the used slurry, but iron can be completely (or almost completely) removed by membrane separation (refer to D of Fig. 2). Further, since the particle size of the chips (for example, about 0.01 to 5 μm) is also smaller than the particle diameter of the abrasive grains, although the used slurry after the secondary centrifugation has residual chips, the chips can be completely separated by the aforementioned membrane separation. (or almost all) removal (refer to D of Figure 2).

The used slurry after the membrane (membrane filtration) discharged from the membrane separation unit 15 (filtration membrane module) is supplied to the component adjustment unit 16 to adjust the composition. Specifically, in the component adjusting unit 16, the separated matter separated by the collecting unit centrifugal separator 120 is added to the used slurry after permeabilization (see E of FIG. 1 and E of FIG. 2), Add (add) new coolant and new abrasive particles. Thereby, the component adjustment unit 16 is adjusted to a predetermined component (composition: see H of FIG. 2). In the material balance shown in Fig. 2, the component adjusting unit 16 of the present embodiment is A new coolant and 10 parts by weight of new abrasive particles were added one by one. In this manner, in the component adjusting unit 16, the component that has been subjected to centrifugation once is added to the used slurry after the membrane separation, in order to secure the recovery rate of the coolant and the abrasive grains. That is, the components separated by one centrifugal separation contain almost no chips and iron fractions. In other words, the separated components are almost composed of a coolant and abrasive grains. Therefore, the recovery rate of the coolant and the abrasive grains can be improved by not recycling the separated components. In the present embodiment, the recovery rates of the coolant and the abrasive grains are both 80%, but are not limited to this value. Further, the recovery rates of the coolant and the abrasive grains may also be different.

The iron concentration of the regenerated slurry obtained in the above manner is, for example, 200 ppm.

In the regenerative device 10 of the present embodiment, by supplying air to the used slurry in the iron separation storage unit 13, the proportion of iron oxide in the used iron in the slurry increases due to oxidation of iron. Since the iron oxide has a larger particle diameter than the other components of iron (iron (iron powder, iron particles) or iron ions), it can be sufficiently separated by the centrifugal separator 14 for iron separation. Therefore, in the regenerating apparatus 10, most of the iron fraction can be separated from the used slurry by the centrifugal separator 14 for iron separation (i.e., by secondary centrifugation). As a result, a regenerated slurry having a low iron concentration (for example, an iron concentration of 1000 ppm or less) can be obtained. The details are as follows.

By pumping the used slurry, the iron and iron ions in the iron contained in the used slurry are oxidized to become iron oxide having a larger particle size than the iron (iron powder, iron particles) or iron ions. . That is, used When the slurry is supplied with air, the iron ions combine with the oxygen in the air to form iron oxide, and the iron dissolves into iron ions due to the moisture contained in the slurry, and then combines with the oxygen in the air to become iron oxide. Therefore, the proportion of iron oxide in the iron component (iron, iron ion, iron oxide) becomes large. Here, in the horizontal centrifugal separation, the used slurry in the centrifugal separation is less likely to come into contact with the air. Therefore, in the iron separation storage portion 13 before the centrifugal separation, iron or iron ions contained in the used slurry can be effectively oxidized by actively supplying air to the used slurry. By increasing the proportion of iron oxide having a large particle diameter in this manner, in the centrifugal separator 14 for iron separation, most of the iron fraction can be separated from the used slurry. In this way, in the regeneration device 10, a regenerated slurry having a low iron concentration can be obtained. In other words, it is possible to obtain a regenerated slurry which is capable of suppressing an increase in viscosity and a deterioration in cleanability in a washing step after ingot slicing, from the used slurry.

In other words, in the regenerating apparatus 10, even if iron content contained in the regenerated slurry is increased due to use, horizontal air separation (centrifugal separator for iron separation) can be used by supplying air to the used slurry. 14 A regenerated slurry in which the iron concentration of the degree of increase in viscosity does not occur in the regenerated slurry is obtained.

Further, in the regenerating apparatus 10 of the present embodiment, since the membrane separation unit 15 is provided, it is possible to separate the iron fraction (iron fraction having a small particle diameter) which cannot be separated from the used slurry by centrifugal separation. Thereby, it is possible to surely obtain a regenerated slurry having a low iron concentration.

Further, the slurry regenerating apparatus and the slurry regenerating method of the present invention are not limited to the above-described embodiments, and the present invention is not deviated from the gist of the present invention. Of course, various changes can be added.

The regenerating device 10 of the above-described embodiment is configured to supply air to the used coolant stored in the separation portion storage tank 130, but is not limited to such a configuration. As long as the air from the air supply portion is at a place where the coolant has been supplied, the air may be supplied to the used coolant before the centrifugal separation (secondary centrifugal separation in the above embodiment), that is, not limited to any place. For example, the place where the air supply portion 135 supplies air may be a liquid supply pipe that has been used to transport the coolant from the recovery portion storage tank 111 to the separation portion storage tank 130, or has been used to transfer the coolant from the separation portion storage tank 130 to the iron. The liquid supply tube or the like of the centrifugal separator 14 for separation is separated. In addition, in the case where the piping for circulating the used coolant stored in the separation portion storage tank 130 is separately provided, the air supply unit may be configured to supply air or the like into the piping. Further, the air supply unit may supply air to each part or a part of each of the above parts.

In the regenerating apparatus 10 of the above-described embodiment, the centrifugal separation and the membrane separation are performed simultaneously after the centrifugal separation and the secondary centrifugation of the used slurry, but the configuration is not limited thereto. For example, as shown in FIG. 3, the regeneration apparatus 10A may be configured to perform only membrane separation after performing centrifugal separation and secondary centrifugal separation in sequence. In other words, the collection unit centrifugal separator 120, the iron separation centrifugal separator 14, and the membrane separation unit 15 may be connected in series.

Further, the number of times of centrifugation in the regeneration device may be three or more times.

Further, although the regeneration apparatus 10 of the above embodiment includes the centrifugal separators 120 and 14 and the membrane separation unit 15, the configuration is not limited to this configuration. to make. For example, as shown in FIG. 4, the regeneration apparatus 10B may be configured to include only the centrifugal separator 14. That is, the configuration in which the membrane separation unit 15 is not provided may be employed. According to this configuration, the proportion of iron oxide in the iron fraction of the used slurry is increased by the pumping, so that the iron fraction can be sufficiently separated (removed) from the used slurry by centrifugal separation alone.

Further, as shown in the reproduction device 10B of Fig. 4, the component adjustment unit may not be provided. In this case, when the obtained regenerated slurry is reused, a new coolant and new abrasive grains can be added.

The centrifugal separator of the regenerating apparatuses 10, 10A, and 10B is not limited to the horizontal type centrifugal separator, and may be a vertical type centrifugal separator that rotates the object to be separated by a rotating shaft extending in the vertical direction as a center of rotation. .

In the regenerating apparatus 10 of the above-described embodiment, the centrifugal separation is performed once by the first centrifugal separator, and the second centrifugal separation and the third centrifugal separation are performed by the second centrifugal separator. However, the configuration is not limited thereto. For example, the entire centrifugal separation may be carried out by a common centrifugal separator, or the centrifugal separation may be carried out by a different centrifugal separator.

Here, the above embodiment will be briefly described.

(1) In the foregoing embodiment, air is supplied to the used slurry, and the used slurry of the supplied air is subjected to centrifugal separation. Therefore, among the iron components contained in the used slurry, iron ions dissolved in the water contained in the used slurry are oxidized to become iron oxide. Therefore, most of the iron can be separated or removed by centrifugation rotating about a certain direction of the axis. Thereby, it is possible to obtain a lower concentration of iron Slurry. The details are as follows.

When the air is supplied to the used slurry, the iron ions of the iron contained in the used slurry are oxidized to become iron oxide and precipitate. In other words, when the air is supplied to the used slurry, the iron ions combine with the oxygen in the air to form iron oxide, or the iron dissolves into iron ions due to the moisture contained in the slurry, and then combines with the oxygen in the air. Iron oxide. Therefore, the proportion of iron oxide in the iron component (iron, iron ion, iron oxide) becomes large.

By increasing the proportion of the iron oxide having a large particle diameter in this manner, it is possible to efficiently separate or remove the iron by centrifugal separation. As a result, a regenerated slurry having a lower iron concentration can be obtained. In other words, it is possible to obtain a regenerated slurry which can suppress the deterioration of the cleaning property in the cleaning step after the ingot is cut, and which can suppress the increase in the viscosity.

As described above, even if the iron content contained in the regenerated slurry is increased by use, the iron concentration can be obtained by centrifugally separating the air supplied to the used slurry, and the viscosity of the regenerated slurry does not rise. The degree of regeneration of the slurry.

(2) The slurry regenerating apparatus may further include: a storage tank for storing the used slurry; and a stirrer for stirring the used slurry stored in the storage tank. The air supply portion may also supply air to the aforementioned used slurry stored in the storage tank. The centrifugal separation unit may also discharge the used slurry stored in the storage tank from the storage tank, and centrifuge the separated used slurry. Further, in the slurry regeneration method, air may be supplied to the used slurry stored in the storage tank, and the used slurry stored in the storage tank and supplied with the air may be further stirred.

According to these configurations, the supplied air can be sufficiently present in the entire slurry to be stored in the storage tank by stirring. Therefore, the oxidation of iron and iron ions contained in the used slurry can be efficiently performed.

(3) In the slurry regenerating apparatus, the centrifugal separation unit may have a horizontal centrifugal separator that rotates the used slurry to have a horizontal or substantially horizontal axis as a center of rotation. Further, in the slurry regeneration method, the axis which is the rotation center of the centrifugal separation may be a horizontal or substantially horizontal axis.

In the horizontal centrifugal separation (centrifugation in which the used slurry is rotated in a horizontal or substantially horizontal axis as a center of rotation), the air is less likely to contact the used slurry in the centrifugation. However, according to the above configuration, iron and iron ions contained in the used slurry are oxidized by supplying air to the used slurry before centrifugation, so that even horizontal separation can be separated or removed. Part of the aforementioned iron.

(4) In the slurry regeneration device, it is preferable to further include a membrane separation unit that performs membrane separation on the used slurry after the centrifugal separation. Further, in the slurry regeneration method, it is preferred that the above-mentioned used slurry after centrifugation is further subjected to membrane separation.

According to these configurations, it is impossible to separate the iron fraction (the iron component having a small particle diameter) separated from the used slurry by centrifugation by membrane separation. As a result, a regenerated slurry having a lower iron concentration can be obtained.

(5) In addition, the configuration of centrifugation and membrane separation may not be performed in sequence, and the used slurry for supplying air may be simultaneously used instead. The composition of centrifugal separation and membrane separation. In other words, the slurry regenerating device may further include a membrane separation unit for extracting the used slurry stored in the storage tank from the storage tank to perform membrane separation, and then using the used slurry after separation by the membrane. The permeable liquid is returned to the aforementioned storage tank. The centrifugal separation unit may return the centrifuged separated slurry to the storage tank. Furthermore, in the slurry regeneration method, the used slurry stored in the storage tank may be taken out from the storage tank, and membrane separation may be performed, and the permeated liquid permeated liquid separated by the membrane may be returned to the foregoing. The storage tank is simultaneously returned to the storage tank by the centrifugally separated used slurry.

In this manner, by performing centrifugation that separates the components having a large particle diameter from the membrane separation, it is possible to suppress membrane clogging at the time of membrane separation as compared with the case where only membrane separation is performed.

(6) The above embodiment is a technique for obtaining a regenerated slurry by removing the aforementioned chips from a used slurry containing chips generated when a wire saw cuts an ingot, wherein air is supplied to the used slurry and supplied The regenerated slurry is obtained by centrifuging the used slurry of air.

According to this configuration, since the concentration of iron contained in the regenerated slurry can be kept low, it is difficult to cause an increase in viscosity due to use, and the cleaning property such as slicing of the ingot after cutting the ingot is performed. Deterioration can be suppressed.

As apparent from the above, the present invention can provide a slurry regenerating apparatus for regenerating a used slurry, a slurry regenerating method, and a regenerated slurry regenerated by the slurry regenerating method, thereby obtaining the same viscosity suppressing effect. At the same time, it is possible to suppress the regenerated slurry in which the cleaning property is deteriorated in the washing step after the ingot block cutting.

10‧‧‧Slurry regeneration device

11‧‧‧Abrasive Grain Recycling Department

13‧‧‧Isolation Department for Iron Separation

14‧‧‧Separation centrifuge for iron separation

15‧‧‧ Membrane Separation Department

16‧‧‧Component Adjustment Department

110‧‧‧Abrasive grain recovery storage

111‧‧‧Recycling storage tank

112‧‧‧Recycling mixer

113‧‧‧Agitating wing

114‧‧‧Rotary axis

115‧‧‧Motor

120‧‧‧Recycling Centrifuge

122‧‧‧ rotating body

124‧‧‧Separate discharge

125‧‧‧Export

130‧‧‧Separation storage tank

131‧‧‧Separator Mixer

132‧‧‧Agitator wing

133‧‧‧Rotary axis

134‧‧‧ motor

135‧‧ Air Supply Department

136‧‧‧Air supply pipe

140‧‧‧Waste storage tank

150‧‧‧ hollow fiber membrane

151‧‧‧Shell

160‧‧‧Adjustment storage tank

161‧‧‧Recycling Supply Division

162‧‧‧Component Supplement

A‧‧‧Used slurry

B‧‧‧Used slurry after a centrifugal separation

C‧‧‧Used slurry after secondary centrifugation

D‧‧‧Three times of centrifugal separation + used slurry after membrane separation

E‧‧‧Separation after centrifugation

F‧‧‧Separators after secondary centrifugation

G‧‧‧Separators after three centrifugation

H‧‧‧ Regenerated slurry

Claims (11)

A slurry regenerating device is a slurry regenerating device that regenerates a used slurry containing chips generated when a wire saw is used to cut an ingot, and the slurry regenerating device includes an air supply portion. The supplied slurry is supplied with air; and the centrifugal separation section centrifugally separates the used slurry which has been supplied with air by the air supply unit. A slurry regenerating apparatus according to claim 1, comprising: a storage tank for storing the used slurry; and a mixer for stirring the used slurry stored in the storage tank, wherein the air supply unit is stored in the foregoing The used slurry is supplied with air in the storage tank, and the centrifugal separation unit extracts the used slurry stored in the storage tank from the storage tank, and centrifugally separates the derived used slurry. The slurry regenerating apparatus according to claim 1 or 2, wherein the centrifugal separation unit includes a horizontal centrifugal separator that rotates the used slurry to have a horizontal or substantially horizontal axis as a rotation center to perform centrifugal separation. The slurry regenerating apparatus according to claim 1 or 2 further comprising a membrane separation unit that separates the centrifuged separated slurry from the membrane. The slurry regenerating apparatus according to claim 2, further comprising a membrane separation unit that extracts the used slurry stored in the storage tank from the storage tank and separates the membrane, and separates the membrane The permeable liquid of the slurry is returned to the aforementioned storage tank; The centrifugal separation unit returns the centrifuged separated slurry to the storage tank. A slurry regeneration method is a slurry regeneration method for regenerating a used slurry containing chips generated by cutting a ingot using a wire saw, supplying air to the used slurry, and The used slurry of this air has been subjected to centrifugation. The slurry regeneration method of claim 6, wherein the air is supplied to the used slurry stored in the storage tank; the used slurry stored in the storage tank and supplied with the air is further stirred; and the stirring is performed. The used slurry has been centrifuged. The slurry regeneration method according to claim 6 or 7, wherein the axis of the centrifugal separation rotation center is a horizontal or substantially horizontal axis. The slurry regeneration method according to claim 6 or 7, wherein the previously used slurry after the centrifugation is further subjected to membrane separation. The method for regenerating a slurry according to claim 7, wherein the used slurry discharged from the storage tank is taken out from the storage tank and subjected to membrane separation, and the permeated liquid of the used slurry is returned to the foregoing The storage tank is simultaneously returned to the aforementioned storage tank by the centrifugally separated used slurry. A regenerated slurry is a regenerated slurry obtained by removing the aforementioned chips from a used slurry containing chips generated by cutting a ingot using a wire saw, the regenerated slurry being supplied with air to the used slurry, and It is obtained by centrifuging the used slurry supplied with the air.