JP2003094146A - Recycling method for molding sand for casting mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycling method for molding sand for a casting mold, taking account of environmental aspects such as the re-use of waste sand which used to be dumped mostly as an industrial waste, converting it into valuables by feeding it to a green mold sand treatment line as supplementary sand. SOLUTION: The recycling method is characterized by comprising a process to recover the waste sand discharged from a molding sand processing line for casting mold, a process to produce bentonite-coated sand by mixing treatment at least with bentonite after applying regeneration treatment to the recovered waste sand, and a process to feed the bentonite-coated sand as the supplementary sand into the recovered sand in the green mold sand treatment line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling casting sand for casting, which processes waste sand discharged from the casting sand processing line for casting and supplies it as supplementary sand to the raw sand processing line.

[0002]

2. Description of the Related Art Conventionally, a part of waste sand discharged from a foundry sand treatment line for molds is reclaimed as core sand and returned to the line as a core, and is also used as a material for roadbed materials, etc. Most sand is disposed of as industrial waste such as landfill. Further, in recent years, there has been seen an example in which the waste sand is subjected to a simple regeneration treatment and collected in a molding line, but this is not common. On the other hand, in the raw sand treatment line, most of the raw sand after unmolding is sent to the sand treatment line to be recovered sand, which is reused as raw sand for casting molds.

[0003] Normally, the raw sand and the core attached to the casting rough material after the mold removal is discarded outside the sand treatment line, or a part of the recovered sand is extracted and discarded, and the raw sand is then discarded. The recovered sand flowing through the treatment line will be gradually reduced.

Therefore, in the raw sand treatment line, reclaimed sand and / or fresh sand is added to the recovered sand as supplementary sand, and kneading treatment is carried out so that it can be reused as raw mold sand. Then, during this kneading process, bentonite that has become inactive due to burning is replenished, and a method for recycling green sand is used to form raw sand for molding by performing kneading by adding water. . It is said that it is desirable that the surface of the sand particles of the green sand for casting mold is uniformly and sufficiently coated with bentonite.

[0005]

However, according to the conventional method for recycling raw sand in the conventional raw sand treatment line as described above, it is difficult to coat the replenishment sand put in the recovered sand with bentonite in a required state. Therefore, a molding mold that does not have the required properties occurs, there is a risk of causing a problem in the product yield reduction and post-treatment process, moreover, in order to bring it closer to the required mold sand for molding, a long time kneading There were problems such as the cost. In addition, since waste sand discarded outside the casting sand processing line for casting molds including the raw sand processing line is not effectively used, resource saving and environmental measures cannot be said to be sufficient.

The present invention has been made in view of the above problems, and waste sand discharged from a casting sand processing line for molds is mixed with at least bentonite to prepare bentonite-coated sand, and raw sand processing is performed. By supplying the sand as supplementary sand to the line sand, the properties of the raw sand processing line sand can be adjusted in a short time, and the casting that is environmentally friendly, such as the recycling of waste sand, which is originally industrial waste, into a valuable resource. It provides a method of sand recycling.

[0007]

In order to achieve the above-mentioned object, the method of recycling foundry sand for casting in the present invention is
A step of collecting the waste sand discharged from the foundry sand processing line for a mold; and after performing a sand regeneration treatment on the collected waste sand,
It is characterized by having a step of performing a mixing treatment with at least bentonite to produce bentonite-coated sand; and a step of supplying the bentonite-coated sand to the recovered sand of the raw sand treatment line as make-up sand.

The method for recycling foundry sand for casting according to the present invention includes the step of collecting waste sand discharged from the foundry sand processing line for casting; and mixing the collected waste sand with at least bentonite. And a step of producing bentonite-coated sand, and a step of supplying the bentonite-coated sand to the recovered sand of the raw sand treatment line as supplementary sand.

Furthermore, the method of recycling foundry sand for casting molds according to the present invention comprises a step of recovering waste sand discharged from the raw sand processing line; at least bentonite after the recovered waste sand is subjected to sand reclamation processing. And a step of producing bentonite-coated sand, and a step of supplying the bentonite-coated sand to the recovered sand of the raw sand treatment line as supplementary sand.

In addition, the method of recycling foundry sand for molds according to the present invention comprises the step of collecting waste sand discharged from the raw sand processing line; and mixing the collected waste sand with at least bentonite. A step of producing bentonite-coated sand, and a step of supplying the bentonite-coated sand to the recovered sand of the raw sand treatment line as supplementary sand.

Further, in the method for recycling foundry sand for casting molds according to the present invention, the bentonite-covered sand forming step comprises reclaimed sand or recovered waste sand, powdered bentonite, and the same weight or more relative to the powdered bentonite. It is characterized in that the process is characterized by mixing with certain water and then drying the mixture. Further, in the method for recycling foundry sand for casting molds according to the present invention, the step of drying the mixture is characterized in that heating or a heating and depressurization process is performed.

In addition, the method of recycling foundry sand for casting according to the present invention comprises the step of mixing the waste sand discharged from the casting sand processing line for casting with at least bentonite to produce bentonite coated sand; And a step of using the bentonite-coated sand as supplementary sand to the foundry sand treatment line for a mold. The method further comprises a step of mixing the reclaimed sand subjected to the sand reclaiming treatment with at least bentonite to produce bentonite coated sand, which is used as supplementary sand to the foundry sand treatment line for a mold.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the term "casting sand treatment line for casting molds" as used herein means a sand treatment line for casting sand for casting production, including raw sand, self-hardening sand and shell sand. It means that the type of sand does not matter. Further, in the present invention, "waste sand" refers to sand discharged outside the casting sand treatment line such as raw sand and core sand adhered to the casting material after the mold is disintegrated, and the sand is mixed by the core sand. It also includes sand from which some of the recovered sand has been extracted to prevent unnecessary build-up of impurities. Further, in the present invention, the "sand reclaiming process" means removing impurities attached to the periphery of the sand by a sand reclaiming device. There are various types of sand reclaimers, such as dry type, wet type, and roast type, but the type is not limited in the present invention.

In the present invention, "at least bentonite" is meant to include the case where, in addition to bentonite, components necessary for the green sand for molding are included. In the present invention, the “mixing treatment” means to disperse reclaimed sand, bentonite, and water to uniformly mix them. By this treatment, bentonite containing water is attached around the particles of reclaimed sand or the like. For this mixing, use an agitator as a mixer.
Although a mixer type mixer is preferable, other types of mixers can be used depending on the conditions.

In the present invention, the term "recovered sand" refers to sand recovered for reuse after being unmolded. In the present invention, "supplementary sand" means sand to be supplied to the raw sand treatment line before or simultaneously with kneading. In the present invention, "bentonite-coated sand" refers to sand coated with bentonite. Then, "manufacture bentonite-coated sand"
Is the waste sand itself or the sand after the sand regeneration treatment is coated with bentonite, more specifically, the waste sand itself or the sand after the sand regeneration treatment is applied to an agitator type mixer in which the container can be heated. And bentonite are added, and a mixture is obtained by stirring for an arbitrary time, water having the same weight or more with respect to bentonite is added little by little to this mixture, and while mixing, heating the container of the mixer,
It is made by drying a mixture of sand and bentonite.

In the present invention, "powdered bentonite" means bentonite which is powdery and 100% active, and its kind is not limited. In the present invention, "drying the mixture" means reducing the water content of the mixture,
The method does not matter. Further, "the bentonite-coated sand is used as the supplementary sand to the sand processing line for casting mold" may be directly performed by the manufacturer of the bentonite-coated sand or may be performed by the person who purchased from the manufacturer.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. First, when the mold made in FIG. 1 is disassembled, most of the sand constituting the mold is directly recovered and returned to the kneading step as recovered sand. The sand that does not become the recovered sand among the sands that compose the mold is selected as waste sand and sent to the sand reclamation process to be reclaimed by the sand reclamation machine. Since the waste sand collected by the dust collector in the raw sand treatment line is a fine powder and cannot be used for the bentonite-coated sand of the present invention, it is recycled or discarded for use as a roadbed material or the like.

The waste sand from which the impurities adhering to the sand have been removed by the sand reclaiming device is sent to the step of producing bentonite coated sand and regenerated into bentonite coated sand supplied to the kneading step of the raw sand treatment line. Will be done. Subsequently, this bentonite-coated sand is supplied to the kneading step and kneaded with the recovered sand in a kneader to produce a desired molding sand for green mold. Then, this raw molding sand is sent to a molding machine to mold a mold having desired properties.

It is also one of possible embodiments of the present invention that the recovered and sorted waste sand is directly sent to the bentonite-coated sand producing step without being subjected to the sand reclamation treatment (FIG. 2). In this case, since a sand reclaimer is not required, it is possible to reduce the cost and the waste sand treatment time, but the sand property is inferior to the waste sand subjected to the sand reclaiming treatment.

In the process of producing the bentonite-coated sand used in the present invention, water having the same weight or more relative to the powdered bentonite is used for the following reason. That is, in the conventional kneading process for producing the green sand for mold, the active bentonite is usually 7 to 8% and the water content is 3 to 4%.
%, But this water content is less than 50% with respect to the active bentonite to which the powdered bentonite and the residual bentonite to be added are added, and when used as green sand for casting, it is usually It is almost never set above this amount of water. On the other hand, in the present invention, in order to uniformly coat the bentonite with sand, the above conditions are preferable, and when the water content is less than the same (100%) with respect to the powdered bentonite, it is powdered. This is because bentonite cannot be uniformly mixed and coated on recycled sand or the like in a short time.

If the ratio of water to the weight of the powdered bentonite is excessive, the mixing and drying steps become difficult.
It is more preferably ˜3 times.

In the present invention, the supplementary sand is bentonite-coated sand formed by coating the sand with bentonite, and the recycled sand or the recovered waste sand, the powdered bentonite and the powdered bentonite have the same weight or more. Is mixed with water, and then the mixture is dried. Then, considering the efficiency of the kneading step, the bentonite-coated sand generally contains 5.5-7.0% of bentonite.

In the present invention, heating in the drying step has an effect that uniform coated sand can be obtained in a shorter time than in the case without heating. The heating method is
For example, there is a hot air generator, mixer-vessel heating, and the like.

Further, in the present invention, the heating and depressurizing treatment in the drying step remove air in the voids between the sand and the bentonite particles. The effect is that a strong coated sand can be obtained.

In the method of recycling foundry sand for casting molds according to the present invention, the waste sand recovered after the mold is separated is sold between the mold manufacturer and the sand reclaimer, and the sand reclaimer who purchased the waste sand disposes of the waste sand. When the sand is coated with bentonite to produce bentonite-coated sand, and then the bentonite-coated sand is used as supplementary sand for sale to or from a sand reclaimer or a holder of a raw sand treatment line or a foundry trader. If the mold manufacturer does not have a sand reclaimer, the waste reclaimer is passed to the sand reclaimer for sand reclamation, and the reclaimed sand is processed into bentonite coated sand. You can also ask them to do it. At this time, the waste sand before the bentonite coating treatment is subjected to sand treatment by a sand regenerator as needed.

It is also possible for the mold manufacturer to reclaim the waste sand by himself and sell this sand with a bentonite-coated sand manufacturer to produce bentonite-coated sand.

[0027]

EFFECTS OF THE INVENTION The present invention produces bentonite-coated sand by subjecting waste sand discharged from a casting sand processing line for molds such as a raw sand processing line to mixing treatment with at least bentonite to prepare bentonite-coated sand. By supplying as supplementary sand to the raw sand treatment line sand, the properties of the raw sand treatment line sand can be adjusted in a short time, and the waste sand conventionally treated as industrial waste can be supplied to the raw sand treatment line sand. Since it can be effectively used as replenishment sand, it has an extremely excellent effect such as being environmentally friendly.

[Brief description of drawings]

FIG. 1 is a sand flow chart showing an embodiment of a method for recycling foundry sand for casting according to the present invention.

FIG. 2 is a sand flow chart showing an embodiment of a method for recycling foundry sand for casting according to the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Nobuichi Ando             Shintoko, 3-1, Honohara, Toyokawa City, Aichi Prefecture             Toyokawa Manufacturing Co., Ltd.

Claims (8)

[Claims] [Claim 1] A step of collecting waste sand discharged from a foundry sand treatment line for a mold; and a sand reclamation treatment of the collected waste sand, followed by a mixing treatment with at least bentonite to coat bentonite. A step of producing sand, and a step of supplying the bentonite-coated sand to the recovered sand of the raw sand processing line as make-up sand; 2. A step of collecting waste sand discharged from a casting sand processing line for a mold; a step of mixing the collected waste sand with at least bentonite to produce bentonite-coated sand; Supplying bentonite coated sand to the recovered sand of the raw sand treatment line as make-up sand;
And a method for recycling foundry sand for casting. 3. A step of collecting waste sand discharged from a raw sand treatment line; after performing sand regeneration treatment on the collected waste sand, at least mixing treatment with bentonite is performed to obtain bentonite-coated sand. And a step of: supplying the bentonite-coated sand to the recovered sand of the raw sand processing line as supplementary sand. 4. A step of collecting waste sand discharged from a raw sand treatment line; a step of mixing the collected waste sand with at least bentonite to prepare bentonite-coated sand; And a step of supplying sand to the recovered sand of the raw sand processing line as make-up sand; 5. The method for recycling foundry sand for casting according to any one of claims 1 to 4, wherein the step of producing the bentonite-coated sand comprises reclaimed sand or recovered waste sand and powder. A method for recycling foundry sand for casting, which comprises: mixing bentonite with water, and water having an amount equal to or more than the weight of the powdery bentonite, and then drying the mixture. 6. The method for recycling foundry sand for casting according to claim 5, wherein in the step of drying the mixture,
A method for recycling foundry sand for casting, which comprises heating or performing decompression treatment together with heating. 7. A waste sand discharged from a casting sand processing line for molds is mixed with at least bentonite,
A method of recycling foundry sand for casting, comprising: a step of producing bentonite coated sand; and a step of using the bentonite coated sand as supplementary sand to the foundry sand processing line for casting. 8. A method comprising: mixing the reclaimed sand that has been reclaimed with at least bentonite to produce bentonite-coated sand, which is used as supplementary sand to a foundry sand treatment line for a mold. Method for recycling foundry sand for casting.