RECLAMATION METHOD OF FOUNDRY SAND

Abstract

To provide a reclamation method of foundry sand capable of suppressing deterioration in strength of core after remanufacturing. A reclamation method of foundry sand includes: a preparation step for preparing foundry sand to which a binder is adhered; a washing step for washing the foundry sand prepared in the preparation step; a polishing step for polishing the foundry sand washed in the washing step; and rinsing step for rinsing the foundry sand polished in the polishing step.

Claims

1. A reclamation method of foundry sand, comprising: preparing foundry sand to which a binder is adhered; washing the prepared foundry sand; polishing the washed foundry sand; and rinsing the polished foundry sand.

2. The reclamation method of foundry sand according to foundry sand according to claim 1, wherein the foundry sand is polished by agitating the foundry sand in contact with a solvent and rubbing the foundry sand against each other.

3. The reclamation method of foundry sand according to claim 2, wherein the amount of solvent is 4 to 20 mass % of the foundry sand that has been washed.

4. The reclamation method foundry sand according to claim 2, wherein the solvent is water.

5. The reclamation method of foundry sand according to claim 2, wherein agitating is performed at an agitation speed of 1 to 12 m/s in polishing the foundry sand.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 is a flowchart of a reclamation method of foundry sand according to this embodiment; and

[0011] FIG. 2 is a graph showing a bending strength of a core manufactured using fresh sand, a core manufactured using reclaimed sand according to an Example and a core manufactured using reclaimed sand according to a comparative example.

DESCRIPTION OF EMBODIMENTS

[0012] Specific embodiments to which the present disclosure is applied will now be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. The present disclosure is not limited to the following embodiments, and may be modified accordingly without departing from the purport. In order to clarify the explanation, the following descriptions and drawings are simplified where appropriate. In the present disclosure, regarding the symbol - (i.e., to) indicating the numerical range, the numerical values described before and after the symbol is included as the lower limit and upper limit of the numerical range.

[0013] FIG. 1 is a flowchart of a reclamation method of foundry sand according to this embodiment. As shown in FIG. 1, the reclamation method of foundry sand according to this embodiment includes Step S1 to Step S4.

[0014] Step S1 is a preparation step for preparing foundry sand with a binder adhered thereto. A binder is a material for bonding foundry sand to each other in manufacturing a core. One example thereof is water-soluble binder such as sodium silicate binder. In the preparation step, foundry sand with binder adhered thereto can be obtained by pulverizing a core, for example.

[0015] Step S2 is a washing step for washing foundry sand prepared in the preparation step. In the washing step, a solvent for dissolving the binder and foundry sand are mixed and agitated to remove the binder adhered to the foundry sand. In the case where the binder is water-soluble, water can be used for the solvent. Especially, in the case where the binder is a sodium silicate binder, it is preferable to use water at 70 to 100 C. from the viewpoint of efficiency of removal of the binder. Alternatively, water at 100 to 120 C. may be used under a pressure higher than saturated water vapor pressure. In the case where the temperature of the water is 70 C. or higher, the binder can be eluted quickly and the washing time can be shortened.

[0016] Step S3 is a polishing step for polishing the foundry sand washed in the washing step. In the polishing step, the foundry sand is polished by rubbing the surface of the foundry sand. The polishing method is not particularly limited, but for example, a method of polishing the foundry sand by rubbing foundry sand against each other is mentioned. In particular, a method of rubbing foundry sand against each other by agitation while keeping the sand in contact with a solvent such as water is preferable. The efficiency of rubbing foundry sand against each other can be improved by bringing the foundry sand in contact with a solvent. In addition, a water-soluble binder can be efficiently removed by using water as a solvent.

[0017] In the case where the foundry sand is agitated in contact with a solvent and the foundry sand is rubbed against each other in Step S3, the amount of solvent is preferably 4 to 20 mass % of foundry sand after the washing step. By setting the amount of solvent to 4 mass % or more of the foundry sand, the whole of the foundry sand can easily come into contact with the solvent and the agitation efficiency can be improved. By setting the amount of solvent to 20 mass % or less of the foundry sand, the dispersion of the foundry sand in the solvent can be suppressed and the frequency of rubbing of the foundry sand against each other can be increased.

[0018] In the case where foundry sand is agitated in water and the foundry sand is rubbed against each other in Step S3, the agitation speed is preferably 1 to 12 m/sec. By setting the agitation speed to 12 m/sec or less, the impact on the foundry sand can be suppressed and the breakage of the foundry sand can be suppressed. By setting the agitation speed to 1 m/sec or more, the polishing time can be shortened. In the case where the agitation speed is 1 m/sec or more, the polishing time can be set to 5 to 10 minutes.

[0019] Step S4 is a rinsing step for rinsing the foundry sand polished in the polishing step. In the rinsing step, the residual fine dirt on the surface of the foundry sand is removed by rinsing the foundry sand with clean water. The rinsing method is not particularly limited, but it is preferable to rinse with volume of water greater than the amount of solvent used in the polishing step.

[0020] The foundry sand reclaimed by the method including Step S1 to Step S4 described above can be suitably used for manufacturing a core since the binder is removed in the washing step and unevenness on the surface of the sand is reduced and smoothed in the polishing step.

[0021] While Step S1 to Step S4 are described in the above example, the polishing step (Step S3) and the rinsing step (Step S4) may be performed in different (i.e., reversed) order. In this case, the residual fine binder and the like on the foundry sand can be removed in the washing step in the rinsing step, and polishing efficiency can be improved.

[0022] The reclamation method of foundry sand according to the present disclosure may include a drying step (not shown) for drying the foundry sand rinsed in the rinsing step after Step S4. Drying makes the foundry sand easier to handle.

[0023] Furthermore, the reclamation method of foundry sand according to the present disclosure may include a fresh sand mixture step (not shown) for mixing the dried foundry sand with fresh sand after the drying process.

[0024] Next, an Example using the reclamation method of foundry sand according to the present disclosure will be described.

Example 1

[0025] First, used core was pulverized to prepare foundry sand with a binder adhered thereto. Next, the foundry sand was washed with water at 120 C. under 0.15 MPa for 5 minutes. Next, the foundry sand was agitated at a speed of 1 m/sec for 5 minutes in a state containing water equivalent to 17 mass % of the washed foundry sand, and the foundry sand was polished. Then, the foundry sand was rinsed with clean water, drained and dried. This was used as reclaimed sand of the Example.

Comparative Example

[0026] In the above procedure, only the polishing step was omitted in producing the reclaimed sand, and the reclaimed sand thus produced was used as the reclaimed sand of the Comparative Example.

Strength Experiment

[0027] A core of the same shape was produced using fresh sand, the reclaimed sand of the Example, and the reclaimed sand of the Comparative Example, and the bending strength was measured by three-point bending test. The measurement results are shown in FIG. 2.

[0028] As shown in FIG. 2, a core produced using the reclaimed sand was inferior in bending strength thereof compared to that of a core produced using fresh sand. On the other hand, a core produced using reclaimed sand in the Example had a bending strength of a same level as the bending strength of a core manufactured using new fresh sand.

[0029] From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.