JP2006281299A - Method for separating molding sand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and surely separate mixed sand of Ni ore slag-made spherical artificial sand and natural silica sand into both these sands. <P>SOLUTION: The mixed sand of the Ni ore slag-made spherical artificial sand and the natural silica sand is heated at ≥400°C, desirably ≥600°C and further desirably at 1000°C and thereafter, the artificial sand and the natural silica sand are classified with a magnetic separation. Regenerated sand is heated at ≥400°C and then, the blackened natural silica sand can be changed into the white color with the casting, and the artificial sand is held to the black color even by heating and therefore, both these sands can be distinguished with the visual observation. The progressing degree of the classification can be confirmed with the naked eye and can surely be separated by performing the magnetic separation to both these sands. In this way, the effect of which the containing ratio of the artificial sand can surely be managed can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting sand separation method capable of separating the artificial sand and the natural silica sand from the mixed sand when using the mixed sand of the spherical artificial sand made of Ni ore and natural silica sand as the casting sand. is there.

Most casting manufacturers use natural silica sand (hereinafter referred to as silica sand) as foundry sand, and produce products using molds made by mixing both materials using furan resin as a binder. By mixing 30-50% of spherical artificial sand (hereinafter referred to as artificial sand) with silica sand, the amount of resin to obtain the same mold strength can be reduced, and because it can prevent vaneing, mixed sand mixed with artificial sand is also used. (For example, Patent Document 1).
However, artificial sand has higher crushing resistance than silica sand, and has characteristics that it is difficult to collect dust because its particle size is slightly larger and the weight of one grain is larger. For this reason, even if silica sand and artificial sand are replenished at the same ratio as the artificial sand content set at the initial stage, artificial sand is mixed in the silica sand, so the proportion of artificial sand in the mixed sand as a whole increases. Resulting in. Therefore, it is necessary to measure the content of artificial sand and manage the entire foundry sand. However, Patent Document 1 does not particularly refer to a method for managing reclaimed sand.

Conventionally, methods shown in Patent Document 2 and Patent Document 3 have been proposed as methods for separating foundry sand. In these documents, both are separated into sand having magnetism and sand not showing magnetism by magnetic separation. In both cases, the sand is heat-treated as a pretreatment in order to improve the magnetic adhesion by removing the binder adhering to the surface of the sand.
Moreover, as a method for analyzing the artificial sand content of the reclaimed sand, calculating the artificial sand content by analyzing MgO not contained in the silica sand but only in the Ni artificial iron spherical artificial sand Is also possible.
Japanese Patent No. 3253579 Japanese Patent No. 1501377 JP 54-45624 A

  However, since the method of analyzing MgO must rely on chemical analysis, the sample weight at one time is as small as about 10 g, and there is a possibility that variations will occur depending on how the samples are taken. Moreover, special analysis equipment is required to analyze MgO, and it is difficult for a casting manufacturer to analyze the MgO independently, and there is a problem that it takes time and cost to request an analysis organization.

  Further, in the method using magnetic separation, the artificial sand can be separated from the mixed sand because the iron ore made of nickel ore contains some iron. However, it is difficult to determine whether or not the separation is accurate, and there is a problem that if the work is carried out too carefully, it takes time and is not industrial.

  The present invention has been made in the background of the above circumstances, and by heating the mixed sand, the silica sand that has turned black by the resin is returned to its original white color, and then magnetically segregated into the spherical iron sand and quartz sand made of Ni ore. It proposes a separation method that makes it possible to accurately separate and analyze the content.

  That is, among the separation methods of foundry sand according to the present invention, the invention according to claim 1 is a method in which a mixed sand of spherical artificial sand made of Ni ore and natural silica sand is heated to 400 ° C. or higher, and then the artificial sand and natural sand are separated by magnetic separation. It is characterized by separating from silica sand.

  According to a second aspect of the present invention, there is provided a method for separating a foundry sand according to the first aspect of the present invention, wherein the heating temperature is set to 1000 ° C., and the gloss is measured simultaneously.

  The invention of the separation method of foundry sand according to claim 3 is the invention according to claim 1 or 2, wherein the amount of chromite in the mixed sand is measured, and the fraction of artificial sand separated by magnetic separation is corrected. It is characterized by doing.

According to the present invention, by heating the reclaimed sand to 400 ° C. or higher, the silica sand blackened by casting can be whitened. On the other hand, the artificial sand remains black even by the above heating, and both can be discriminated visually. By magnetically selecting the mixed sand, the progress of the selection can be confirmed with the naked eye, and the state of being accurately separated can be easily known.
As heating conditions, artificial sand and quartz sand are not sufficiently color-coded if the temperature is less than 400 ° C. Therefore, the heating temperature is 400 ° C. or higher, preferably 600 ° C. or higher, more preferably 1000 ° C., which is usually set at the time of measuring the gross, and it is possible to simultaneously measure the gloss by heating at 1000 ° C.

  The heating time may be set so that the entire sand reaches the heating temperature, but preferably heating for 1 hour or more recommended in the gloss measurement is desirable.

  In the case of not having a heating device, as an alternative method, it is possible to use sand that has been sufficiently heated from a part close to the product when heated by a burner or when the mold is broken. However, heating with a burner does not allow uniform heating, or when sampling from a part close to the product, there is a possibility that unheated sand may be mixed because the amount is small, which is not a preferable method. However, it goes without saying that the heating method is not limited to a specific one in the present invention.

By removing the gloss to some extent or surely by the above heating, the silica sand that has changed to black, which is the color of the resin, is returned to its original white color and can be visually separated from the artificial black sand.
Next, although there are no particular rules regarding magnets used for magnetic separation, it is recommended to use magnets with a relatively high attraction force because those used for general household use have a weak attraction force. It is desirable not to use a magnet that is too strong because it has poor workability and is difficult to handle.

  In addition, when chromite is contained in the mixed sand, the chromite exhibits magnetism and is separated to the artificial sand side by magnetic separation. Therefore, it is desirable to analyze the amount of chromite in the mixed sand by a method such as chemical analysis to correct the magnetically selected artificial sand amount. Note that the amount of chromite can be measured both before and after separation.

As described above, according to the casting sand separation method of the present invention, the mixed sand of Ni ore spherical artificial sand and silica sand is heated to 400 ° C. or higher, and then the artificial sand and silica sand are separated by magnetic separation. Therefore, both of them can be easily and accurately separated in a short time using visual observation, and the content of artificial sand can be accurately managed.
By setting the heating temperature to 1000 ° C., it is possible to measure the gloss as desired simultaneously with the heat treatment for separation, and the working efficiency is greatly improved.

Below, one Embodiment of this invention is described based on FIG.
Prepared as a mixed sand 1 containing Ni ore spherical artificial sand and silica sand in a predetermined mixing ratio and reusing and reusing the mixed casting sand used with furan resin or the like. In addition, the mixing ratio of the artificial sand and the silica sand in the mixed sand is not particularly limited.
The mixed sand 1 contains Ni ore-made spherical artificial sand 1a and silica sand 1b, and both are black by kneading with furan resin.

  The mixed sand 1 is accommodated in a crucible 2 or the like, and is heated at 400 ° C. or higher, preferably 600 ° C. or higher by a heating means such as a heating furnace 3. The heating time is preferably 1 hour or longer. In addition, as above-mentioned, the means for heating mixed sand is not specifically limited, A well-known thing can be used.

In the mixed sand 1 subjected to the heat treatment as described above, the gloss is removed, and the color of the silica sand 1b changes from black to white, while the artificial sand 1a remains black.
The mixed sand 1 subjected to the heat treatment is subjected to magnetic separation using a magnet 5. In addition, when the mixed sand touches the magnet 5 directly, it is difficult to remove the sand adhered during magnetic separation. It is desirable to cover with a synthetic resin film 4 or the like.
In the magnetic separation, only the artificial sand 1a is attracted to the magnet 5 and separated. In magnetic separation, since only the white silica sand 1b remains, it is possible to grasp the remaining amount of the artificial sand 1a at a glance, and it is possible to easily grasp the time when the accurate separation process is performed. In this way, the mixed sand can be accurately separated into artificial sand and silica sand.

  When the mixed sand contains chromite, for example, magnetically selected sand contains chromite in addition to artificial sand. This sand is analyzed by a method such as chemical analysis, and the amount of artificial sand is calculated by knowing the amount of chromite.

An embodiment of the present invention will be described below.
About 100 g of cast sand that has finished the regeneration process is collected from the cast sand mixed with artificial sand and silica sand used in the production line, put in a crucible in a manner to measure the gloss, and 1000 ° C. × 1 in the heating furnace. After heating for a time and cooling, artificial sand was selected using a magnet. At this time, a magnet such as vinyl was covered so that the magnet and sand would not be in direct contact. Artificial sand and quartz sand are color-coded, and magnetic selection is performed until there is no black artificial sand. The total weight before magnetic separation and the weight of silica sand after magnetic separation were measured, and the content of artificial sand in% by weight was measured by the following formula.
Artificial sand content (%) = (total weight−silica sand weight *) / total weight × 100
*) Since artificial sand may be lost during magnetic separation, chromite may be contained in foundry sand if chromite is used as pocket sand or has been used before. Since chromite also contains MgO and is attracted to the magnet, correction is required by measuring Cr ₂ O _{3 in} advance. Table 1 shows typical component compositions of silica sand, chromite, and artificial sand.

  Next, 2 kg of regenerated silica sand and 1 kg of artificial sand are mixed with a mixer to produce simulated mixed sand, 100 g of which is weighed into a crucible and subjected to heat treatment at 1000 ° C. for 1 hour, and heat treatment Both of those that did not perform magnetic separation were subjected to measurement of the artificial sand content. The results are shown in Table 2. The value without heat treatment was less than 30%, whereas the value with heat treatment was a little less than 33%, which was close to the mixing ratio, and it was confirmed that the heat treatment improves accuracy.

It is process drawing which shows the isolation | separation process of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixed sand 1a Artificial sand 1b Silica sand 2 Crucible 3 Heating furnace 5 Magnet

Claims (3)

  A method for separating foundry sand, characterized in that mixed artificial sand made of nickel ore and natural silica sand is heated to 400 ° C or higher, and then the artificial sand and natural silica sand are separated by magnetic separation.   2. The method for separating foundry sand according to claim 1, wherein the temperature of the heating is set to 1000 [deg.] C., and the gloss is measured simultaneously.   3. The method for separating foundry sand according to claim 1, wherein the amount of chromite in the mixed sand is measured to correct the fraction of the artificial sand separated by magnetic separation.

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