JPH07314080A - Method for reconditioning molding sand - Google Patents

Abstract

PURPOSE:To reduce a site area of equipment, to save the equipment cost, to reduce the development of dust and odor and to obtain the low pullution by making a fluidized bed roasting furnace obtaining reconditioned sand by roasting recovered sand the simple, compact and inexpensive condtitution. CONSTITUTION:The recovered sand in shell mold is supplied on a punching plate 51 and also, hot blast is blown from the lower part to the upper part of the punching plate 51. The recovered sand is fluidized and roasted during shifting toward a discharging hole 55 while leaping the recovered sand on the punching plate 51 with the hot blast, and then, the resin is removed from the recovered sand to make the reconditioned sand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reclaiming foundry sand used to reclaim foundry sand used in shell mold casting.

[0002]

2. Description of the Related Art As a method for manufacturing an iron casting part, a shell mold casting method in which a casting mold made of sand is used for casting is used. The mold material used in this shell mold casting consists of sand as the main component, a binder made of resin (phenolic resin, etc.), a shell mold hardening accelerator such as hexamine, and sand such as calcium stearate. It is prepared by mixing additives such as ingredients for loosening. Such foundry sand is usually also called resin coated sand.

[0003] The foundry sand is used as a mold for shell mold casting, and then reclaimed and repeatedly used. The present invention relates to an improvement in a method for reclaiming used molding sand (resin coated sand) so that it can be reused. This casting reclaiming method magnetically separates iron and the like adhering to the surface of the recovered mold material, crushes the mold material into particles of a size suitable for the treatment, and performs fluidized roasting treatment for removing the resin. ,
If necessary, fresh sand is added, and the additives such as the above-mentioned binder and hardening accelerator are mixed in.

[0004]

However, in the conventional method for reclaiming foundry sand, since the structure of the fluidizing roasting furnace and the fluidizing cooling device is complicated and the treatment efficiency is not sufficiently high, each treating device is installed. In addition, it requires a large site area, equipment costs are high, and dust and odors are insufficiently removed.

The present invention has been made in view of such prior arts, and an object of the present invention is to make an apparatus for carrying out each processing step compact and to reduce a site area.
It is an object of the present invention to provide a method for reclaiming foundry sand, which can reduce equipment costs, reduce dust and odor, and reduce pollution.

[0006]

According to a first aspect of the present invention, in a molding sand reclaiming method for reclaiming molding sand used for forming a mold for shell mold casting, the recovered molding material is suitable for fluidized roasting. The above object is achieved by adopting a constitution in which the step of crushing to a size is performed by a hammer mill.

According to a second aspect of the present invention, in a foundry sand reclaiming method for reclaiming foundry sand used to form a mold for shell mold casting, the fluidized roasting step of removing resin from the foundry sand punches the foundry sand. A step of supplying hot air to the plate and circulating hot air upward from the lower side of the punching plate through the molding sand, and moving the molding sand on the punching plate toward the outlet while dancing with the hot air. By doing so, the above object is achieved.

According to the inventions of claims 3 and 4, in addition to the structure of claim 2, the molding sand on the punching plate is fluidized and roasted at a temperature higher than the temperature of the hot air by the combustion of the resin to be removed. Alternatively, the hot air used in the fluidized roasting step is introduced into a cyclone to remove dust by centrifugal separation, and then heated again by a burner and circulated through the punching plate. Thus, the above object can be achieved more efficiently.

According to a fifth aspect of the present invention, there is provided a method for reclaiming foundry sand used to form a mold for shell mold casting, wherein the foundry sand is removed after the fluidized roasting step of removing the resin from the foundry sand. Flow cooling that supplies air onto a punching plate and circulates an air flow upward from below the punching plate through the molding sand, and moves the molding sand on the punching plate toward the outlet while dancing with the air flow. The above object is achieved by adopting a structure having steps.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a layout diagram showing an overall configuration of equipment suitable for carrying out the method for reclaiming foundry sand according to the present invention, and FIG. 2 shows, in order, steps suitable for carrying out the method for reclaiming foundry sand according to the present invention. It is a flowchart. The numbers given to the respective parts in FIG. 1 and the numbers given to the respective steps in FIG. 2 correspond to each other, and the apparatus of the respective numbers carries out the steps of the corresponding numbers.

FIG. 3 is an elevational view of the device taken along line 3-3 in FIG. 1 to 3, 1 is a trolley for collecting molding sand (shell sand) used for forming a mold for shell mold casting, 2 is a skip conveyor for transporting the dolly 1 on which the molding sand is loaded, to a supply position, 3 is a screen for passing the recovered sand from the skip conveyor 2, 4 is a recovered sand hopper for receiving the recovered sand, 5 is an electromagnetic feeder provided at the outlet of the hopper 4, and 6 is the recovered sand supplied from the electromagnetic feeder 5. The belt conveyor 7 is an electromagnetic hanging magnetic separator for separating and removing iron contained in the recovered sand being conveyed.

1 to 3, numeral 8 indicates the recovered sand (collected mold material) supplied from the belt conveyor 6 to a desired size (size suitable for treatment in a fluidized roasting furnace described later). A hammer mill for crushing, 9 is a belt conveyor for carrying crushed recovered sand (casting sand), and 10 is a conveyor for carrying the recovered sand supplied from the belt conveyor 9 to a supply position to a fluidized roasting furnace described later. It is a bucket conveyor for.

FIG. 4 is an elevational view of the device taken along line 4-4 in FIG. In FIGS. 1, 2 and 4, 11
Is a fluidized roasting furnace for burning and removing resin (additive) from the recovered sand (casting sand) supplied from the bucket conveyor 10, and 12 is a screw conveyor for carrying the casting sand discharged from the fluidized roasting furnace 11. , 13 are fluidized cooling devices for cooling the roasted foundry sand.

FIG. 5 is an elevational view of the device taken along line 5-5 in FIG. 1, FIG. 2, FIG. 4 and FIG. 5, 14 is a screw conveyor for conveying the molding sand discharged from the fluid cooling device 13, 15 is an electromagnetic feeder type screen (sieve), 16 is from the screw conveyor 14. It is a bucket conveyor for transporting foundry sand fed through the screen 15 to a feeding position of a predetermined height.

The foundry sand reclaiming apparatus of this embodiment is constructed so that reclaimed sand obtained by reclaiming recovered sand and new mold sand (new sand) are mixed at a fixed ratio. 1, FIG. 2 and FIG. 5, 17 is a reclaimed sand tank for receiving and storing foundry sand (reclaimed sand) reclaimed in each of the above steps from the bucket conveyor 16, and 18 in the reclaimed sand tank 17. A rotary feeder for taking out the reclaimed sand and a belt conveyor 19 for conveying the reclaimed sand supplied through the rotary feeder 18. This recycled sand is mixed (kneaded) with fresh sand described later.

In FIGS. 1, 2 and 5, 31 is a fresh sand supply hopper, 32 is a bucket conveyor for carrying the fresh sand taken out from the hopper 31 to a predetermined feeding position, and 33 is supplied from the bucket conveyor 32. A new sand tank for storing new sand, 34 is the new sand tank 33
Rotary feeder for removing new sand in the container, 35
Is a belt conveyor that conveys the fresh sand supplied through the rotary feeder 34.

FIG. 6 is an elevational view of the device taken along line 6-6 in FIG. In FIGS. 1, 2 and 6, 20
Is a belt conveyor that receives and conveys the reclaimed sand on the belt conveyor 19 and the new sand on the belt conveyor 35, and 21 is a skip conveyor that receives the reclaimed sand and the new sand from the belt conveyor 20 and conveys them to a supply position of a predetermined height. Reference numeral 22 denotes a hopper that receives the molding sand (regenerated sand and new sand) from the skip conveyor 21, and 23 is a sand heater for heating the molding sand supplied from the hopper 22 to a predetermined temperature (for example, about 170 ° C.).

In FIGS. 1, 2 and 6, reference numeral 24 is a kneading mixer. In FIGS. 1 and 2, 36 is a resin supply device for supplying a binder such as phenolic resin, 3
Reference numeral 7 is a hexa-water supply device that supplies a shell mold hardening accelerator such as hexamine, and 38 is a steal supply device that supplies calcium stearate or the like for loosening the foundry sands. Then, with respect to the kneading mixer 24,
In addition to the casting sand (regenerated sand and fresh sand) that has been heat-treated by the sand heater 23, the resin supply device 36, the hexa-water supply device 37, and the steal supply device 38.
Various additives for resin coated sand are supplied from the above, and these are kneaded in the kneading mixer 24.

Referring to FIGS. 1 and 2, the mixer 2
The foundry sand (mold material) kneaded in 4 is supplied onto the cooling vibration conveyor 25. The molding sand is cooled to a predetermined temperature (for example, 80 ° C.) while being dried by the cooling vibration conveyor 25. The foundry sand from the cooling vibration conveyor 25 is passed through the screen (screen) 26 and the bucket conveyor 2
7, the casting sand is further supplied from the bucket conveyor 27 to an RCS (resin coated sand) product hopper 28, and the flexible container bag is filled from the hopper 28.

In FIGS. 1 and 2, reference numeral 30 denotes a dust collector, and each device (each step) listed below is connected to the dust collector 30 through a duct pipe. That is, the screen 3, the recovered sand hopper 4, the belt conveyor 6, the hammer mill 8, the bucket conveyor 10, the fluidized roasting furnace 11, the fluidized cooling device 13, the reclaimed sand tank 17, the belt conveyor 19, the belt conveyor 20, the skip conveyor 21, Sand heater 23, screen 26, RCS
The product hopper 28, the fresh sand supply hopper 31, the fresh sand tank 33, and the belt conveyor 35 are connected to the dust collector 30 through a duct pipe (not shown).

Among these apparatuses, the fluidized roasting furnace 1
1. The fluid cooling device 13 and the sand heater 23 are connected to a cyclone 39 for centrifugally separating dust, which is relatively heavy dust, and are connected to the dust collector 30 via the cyclone 39. Also, the kneading mixer 2
Dust collection inside 4 is carried out by introducing an internal atmosphere into the fluidized roasting furnace 11, whereby the kneading mixer 2
It is also possible to remove the odor of the phenol gas generated in 4 at the same time.

As the hammer mill 8 in FIGS. 1 and 3, for example, a Takeuchi type D crusher manufactured by Takeuchi Iron Works Co., Ltd. can be used. 7 and 8 show the structure of the hammer mill 8 using this Takeuchi type D crusher as an example.
Is a partially cutaway front view of the hammer mill 8, and FIG. 8 is a partially cutaway side view of the hammer mill 8 of FIG. 7. In FIGS. 7 and 8, 40 is a main body case, 41 is a hopper to which collected sand is supplied, 42 is a foreign matter discharge port, 43 is a lining attached to the inner peripheral surface of the case main body 40, and 44 is a central portion of the case main body. A shaft rotatably supported by the shaft 45, a pulley 45 fixed to the protruding end of the shaft 44,
Is a hammer holder fixed to a position inside the case body of the shaft 44, 47 is a hammer, 48 is a hammer pin for detachably attaching the hammer 47 to the hammer holder 46, and 49 is a particle size of crushed recovered sand. It is a sieve for discharging downward (arrow direction) while adjusting.

FIG. 9 is a perspective view showing the hammer 47. The recovered sand is crushed by the hammer mill 8 to a particle size of 10 mm or less. The recovered sand crushed by the hammer mill 8 is conveyed by the belt conveyor 9 toward the bucket conveyor 10. The belt conveyor 9 has a magnetic selection pulley. Therefore, when the belt conveyor 9 conveys the sand. The iron adhering to the recovered sand is separated and removed.

Next, the structure and operation of the fluidized roasting furnace 11 will be described with reference to FIGS. 1 and 4. In FIG. 4, a punching plate 51 is installed in a horizontal direction inside a closed chamber 50 made of a refractory wall, and recovered sand (casting sand) from the bucket conveyor 10 passes through a sand inlet 52 on the upper side of the punching plate 51. Is supplied to. On the other hand, an inlet 53 for hot air is provided in a portion of the closed chamber 50 below the punching plate 51, and a gas burner 54 is connected to the inlet 53, and the gas burner is connected by a blower. The air heated to a high temperature by 54 is blown upward from below through the punching plate 51 and the molding sand on the punching plate 51. On the opposite side of the punching plate 51 from the sand inlet 52 (on the left side in the drawing), a fluidized roasting casting sand outlet 55 is provided.

The specifications of the fluidized roasting furnace 11 are set as follows, for example. The flow rate of the high temperature air supplied to the fluidized roasting furnace 11 by the blower was about 150 m ³ , the temperature of the supplied air (hot air) was about 550 ° C., and the gas burner 5
The static pressure of No. 4 is about 150 mm in water column, the flow rate of fuel gas is about 42 m ^{3 /} hour, and the calorific value of gas burner 54 is about 280,000 / hour.
(Kcal). Thus, in the roasting step of removing the resin from the foundry sand (recovered sand) in the fluidized roasting furnace 11, the foundry sand is supplied onto the punching plate 51, and hot air is passed from below the punching plate 51 through the foundry sand. The punching plate 51
While letting the above foundry sand dance with the hot air, the outlet 55
It is performed while moving toward.

In this case, the foundry sand on the punching plate 51 moves (flows) from the right side of the drawing to the left side of the drawing, while the hot air sent by the blower through the burner 54 is an inlet 53 provided on the left side of the drawing. Is supplied from the direction opposite to the flow direction of the foundry sand. Thus, a fluidized-bed roasting furnace having an extremely compact structure and capable of greatly reducing the area required for installation has been realized.

The diameter of the holes formed in the punching plate 51 is selected to be 0.5 mm to 3.0 mm, more preferably 0.5 mm to 1.5 mm, and the holes are arranged in a vertical and horizontal pitch of about 10 mm. The first arrangement and the first
It is selected as a combination of the second arrangement having a pitch of about 10 mm in the vertical and horizontal directions, which is a half pitch (about 5 mm) vertically and horizontally.

In FIG. 4, the punching plate 5
The hot air that has passed through 1 and the molding sand from below to above is guided to the cyclone 39 from the exhaust port (outlet) 56 provided at the top of the closed chamber 50. In the cyclone 39, relatively large dust is centrifugally separated, and the separated dust is discharged as dust from the lower part of the cyclone 39. on the other hand,
The hot air treated by the cyclone 39 is branched by the damper 57, part (for example, about 10%) is guided to the dust collector 30, and the rest (about 90%) is supplied from the reflux passage 58 to the inflow port 53 through the gas burner 54. Be guided. That is,
The fluidized roasting furnace 11 employs a heat recycling method that reuses a small amount of hot air used for roasting the foundry sand.

In FIG. 4, the punching plate 5 is
1% (for example, 3
%) Resin is contained, and the hot air burns the resin. The temperature of the hot air blown from the gas burner 54 is about 550 ° C., but the combustion temperature of the recovered sand can be raised to about 700 ° C. by the combustion of the resin (self-combustion of the recovered sand). That is, the fluidized-bed roasting furnace 11 is designed to limit the roasting of additives such as resin by effectively utilizing the heat value of the resin-containing recovered sand due to self-combustion, and has a structure with excellent thermal efficiency. .

By the roasting treatment in the fluidized roasting furnace 11, the recovered sand having a particle size of about 10 mm is about 20-25.
It is reclaimed to about 0 mesh (about 100 mesh) foundry sand (reclaimed sand). Further, in the fluidized roasting furnace 11, phenol gas, ammonia gas, C generated during the treatment
Odorous gas containing O, CO _2, etc. can be almost completely burned and removed, and since these burnings are performed in the closed chamber 50, they can be transported using a vibration chute or subjected to fluidized roasting treatment in a rotary kiln. As compared with the conventional method, the emission of dust and odor can be almost eliminated, and a fluidized roasting furnace excellent in low pollution can be configured.

The reclaimed sand from which the resin and the like have been removed in the fluidized roasting furnace 11 is fed to the fluidized cooling device 13 by the screw conveyor 12, and the fluidized cooling device 13 approximately 50
It is cooled from 0 ° C to about 200 ° C. Except for specific specifications such as dimensions and air volume, the fluidized-flow cooling device 13 is structurally structured such that only the gas burner 54 is omitted from the fluidized-bed roasting furnace 11 described above. However, the air (cooling air) discharged from the closed chamber is only guided to the cyclone 39, and fresh air from the blower is introduced from the inlet. In FIG. 4, the parts corresponding to the respective constituent parts of the fluidized-bed roasting furnace 13 of the fluidized-bed cooling device 13 are shown by the same reference numerals with the letter A added.

That is, in this fluid cooling device 13, a punching plate 51A is installed substantially horizontally in a closed chamber 50A, regenerated sand (casting sand) is supplied from the sand inlet 52A onto the punching plate 51A, and a blower is used. An air flow (cooling air) is sent into the closed chamber 50A and circulated upward from below the punching plate 51A through the reclaimed sand, and casting sand on the punching plate 51A is directed toward the discharge port 55A while being danced by the air flow. And move the foundry sand between about 500 ° C. and about 20
It is configured to cool to about 0 ° C. In addition, this cooling method is effective for sand cooling in general molding sand, and can be applied to all molding such as green sand molding and self-hardening molding.

Dust and the like generated in the fluid cooling device 13 is discharged from the exhaust port 56A together with the cooling air into the cyclone 39.
Is introduced into the dust collector 30 through the cyclone 39 and processed. Therefore, the fluidized-bed cooling device 13 is also extremely compact and can greatly reduce the area required for installation, like the fluidized-bed roasting furnace,
In addition, it has a low pollution structure with almost no emission of dust.

In FIGS. 1 and 2, the electromagnetic feeder type screen (sieving) 15 is for adjusting the grain size of the reclaimed sand by vibration. Further, in the foundry sand reclamation apparatus of the present embodiment, the reclamation sand from the reclamation sand tank 18 and the fresh sand from the fresh sand tank 33 are configured to be mixed at a fixed ratio, and the ratio is, for example,
20 kg of new sand is selected for 80 kg of recycled sand. In addition, the sand heater 23 produces about 17
The mixture is heated to about 0 ° C. and is about 15 in the kneading mixer 24.
Kneading of molding sand and additives is performed at about 0 ° C. The foundry sand discharged from the kneading mixer 24 is cooled to about 80 ° C. on the cooling vibration conveyor 25.

The atmosphere in the sand heater 23 is also fed to the cyclone 39 and is subjected to a pollution reduction process.
Further, since dust and odor are likely to be generated in the kneading mixer 24, the atmosphere in the kneading mixer 24 is introduced into the fluidized roasting furnace 11 and sent to the cyclone 39 together with hot air for processing. It

[0036]

As is apparent from the above description, according to the invention of claim 1, in the casting sand reclaiming method for reclaiming the casting sand used for forming the mold of the shell mold casting, the recovered molding material is used. Since the process of crushing to a size suitable for fluidized roasting is performed by a hammer mill, the device for crushing the recovered sand can be made simple, compact and inexpensive, and the site area of the facility can be reduced. Provided is a method for reclaiming foundry sand, which can be reduced and the equipment cost can be saved.

According to the invention of claim 2, in the molding sand reclaiming method for reclaiming the molding sand used for forming the mold of the shell mold casting, the fluidized roasting step for removing the resin from the molding sand comprises the molding sand. Is supplied to the punching plate, hot air is circulated upward from below the punching plate through the molding sand, and the molding sand on the punching plate is moved toward the discharge port while being danced by the hot air. Since it is configured, the fluidized-bed roasting furnace that roasts the recovered sand to obtain the reclaimed sand can have a simple, compact and inexpensive configuration, can reduce the site area of the facility, and reduce the facility cost. There is provided a method for reclaiming foundry sand, which is capable of reducing dust and odor and reducing pollution.

According to the inventions of claims 3 and 4,
In addition to the constitution of claim 2, the molding sand on the punching plate is fluidized and roasted at a temperature higher than the temperature of the hot air by the combustion of the resin to be removed, or is used in the fluidized roasting step. The hot air was introduced into a cyclone to remove dust by centrifugation, then heated again by a burner and circulated through the punching plate, so that the recovered sand is roasted to obtain reclaimed sand. The furnace can be made simple, compact and inexpensive, the site area of the facility can be reduced and the facility cost can be reduced, and moreover, energy can be saved by the effective use of heat, dust and Provided is a method for reclaiming foundry sand that can reduce the generation of odors and reduce pollution.

According to the invention of claim 5, in a foundry sand reclaiming method for reclaiming foundry sand used for forming a mold in shell mold casting, after the fluidized roasting step of removing the resin from the foundry sand, the foundry The sand is supplied onto the punching plate, and an air flow is circulated upward from below the punching plate through the foundry sand, and the foundry sand on the punching plate is moved toward the outlet while being danced by the air flow. Since it is configured to have a fluidized cooling step, a fluidized cooling device for cooling the foundry sand that is regenerated by fluidized roasting can be a simple, compact and inexpensive configuration, and the site area of the facility can be reduced, Provided is a method for reclaiming foundry sand, which can reduce equipment costs, reduce dust and odor, and reduce pollution.

[Brief description of drawings]

FIG. 1 is a layout diagram showing an overall configuration of equipment suitable for carrying out a method for reclaiming foundry sand according to the present invention.

FIG. 2 is a flow chart showing in sequence respective steps suitable for carrying out the method for reclaiming foundry sand according to the present invention.

FIG. 3 is an elevational view of the device taken along line 3-3 in FIG.

FIG. 4 is an elevational view of the device taken along line 4-4 in FIG.

5 is an elevational view of the device taken along line 5-5 in FIG.

FIG. 6 is an elevational view of the device taken along line 6-6 in FIG.

FIG. 7 is a partially cutaway front view of the hammer mill in FIG.

8 is a partially cutaway side view of the hammer mill of FIG.

9 is a perspective view showing a hammer in the hammer mill of FIG. 7. FIG.

[Explanation of symbols]

 1 Shell Sand Recovery Cart 4 Recovery Sand Hopper 5 Electromagnetic Feeder 7 Electromagnetic Suspension Magnetic Separator 8 Hammer Mill 9 Belt Conveyor (with Magnetic Selection Pulley) 10 Bucket Conveyor 11 Fluid Roasting Furnace 12 Fluid Cooling Device 17 Fluid Cooling Device 17 Reclaimed Sand Tank 18 Rotary feeder 20 Belt conveyor 23 Sand heater 24 Kneading mixer 25 Cooling vibration conveyor 28 RCS product hopper 29 Flexible container bag 30 Dust collector 31 Fresh sand supply hopper 33 Fresh sand tank 34 Rotary feeder 35 Belt conveyor 36 Resin supply device 37 Curing accelerator supply device 38 Disentangant supply device 39 Cyclone 40 Hammer mill body case 41 Hopper 44 Shaft 46 Hammer holder 47 Hammer 49 Sieve 50 Closed Chamber 51 Punching plate 52 Sand inlet 53 Inlet 54 Gas burner 55 Discharge port 56 Exhaust port 57 Damper 58 Reflux path

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B22C 9/02 103 B (72) Inventor Koji Tanaka 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Inside the Akashi Plant (72) Inventor Hayashi Ueyama 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Inside the Akashi Factory (72) Tomizo Morita 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Company Akashi Factory (72) Inventor Masanori Tanaka 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Factory (72) Inventor Tamio Nishikawa 1-1 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Inside the factory (72) Inventor Koji Yokoyama 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi factory (72) Inventor Shunji Dan Akira Hyogo No. 1-1 Kawasaki-cho, Ishi-shi Kawasaki Heavy Industries Ltd., Akashi Plant (72) Inventor Masaki Kageyama 1-1, Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi Plant

Claims (5)

[Claims] 1. A method for reclaiming foundry sand used to form a mold for shell mold casting, wherein a step of crushing the recovered template material into a size suitable for fluidized roasting treatment is performed by a hammer mill. A method for reclaiming foundry sand, which is characterized by carrying out. 2. A method for reclaiming foundry sand used to form a mold for shell mold casting, wherein a fluidized roasting step for removing resin from the foundry sand supplies the foundry sand onto a punching plate. At the same time, hot air is circulated upward from below the punching plate through the molding sand, and the molding sand on the punching plate is moved toward the discharge port while being danced by the hot air. How to play. 3. The method for reclaiming foundry sand according to claim 2, wherein the foundry sand on the punching plate is fluidized and roasted at a temperature higher than the temperature of the hot air by burning the resin to be removed. 4. The hot air used in the fluidized roasting step is introduced into a cyclone to remove dust by centrifugation, and then heated again by a burner and circulated through the punching plate. Claim 2
Alternatively, the method for reclaiming foundry sand according to claim 3. 5. A method for reclaiming foundry sand used to form a mold for shell mold casting, in a method for reclaiming foundry sand after a fluidized roasting step for removing resin from the foundry sand.
The molding sand is supplied onto the punching plate, and an air flow is circulated upward from below the punching plate through the molding sand, and the molding sand on the punching plate is moved toward the discharge port while being danced by the air flow. A method for reclaiming foundry sand, which comprises a fluidized cooling step of