JPS5919558A - Method of regenerating and treating mold recovery sand - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recycling mold recovered sand, and more specifically, to a method for recycling mold recovered sand. The present invention relates to a reprocessing method for regenerating sand into foundry sand properties such as υ new sand using a dry process.

Conventionally, for example, CO! In mold making methods such as processes, a method of adding water glass as an inorganic binder is known, but in the above method, 5 to 8% of water glass is added to increase the strength of the mold. For this reason, the surface stability of the mold is poor, and the mold is sintered by heat during casting, resulting in poor collapsibility, making it difficult to remove sand from the casting after casting, and leaving some molding sand on the surface of the casting. There were problems such as burning.

The present applicant has previously discovered that sufficient surface stability can be obtained by applying a microwave heating method to mold molding in order to improve the above-mentioned problems, and has already filed a patent application.

By the way, if the recovered sand generated in large quantities at foundries can be recycled and used as raw material sand for the microwave-curable foundry sand,
It is extremely advantageous because it can reduce the entire production cost and increase productivity, but it is extremely advantageous because it can greatly reduce the manufacturing cost and increase productivity. Therefore, it cannot be used as is, and it is difficult to obtain raw material sand for microwave-curable foundry sand using methods generally known as methods for recycling and recovering old sand.

In other words, conventionally known recycling and recovery methods involve magnetic separation (removal of iron pieces), cooling, and sieving (further pulverizing coarse particles) of the waste sand after molding (mold), pouring molten metal, and breaking the frame (removing the product). , sieving after removing the grains), washing with water, drying, cooling, and further classifying to remove fine powder, or the recovered sand whole leopard 800 obtained as described above. After roasting at a high temperature of °C and cooling, the surface of the roasted sand grains is scrubbed using an appropriate stirrer, etc.
Although there is a roasting scrubbing method that involves cleaning, classifying, and removing fine particles, the recycling treatment of recovered sand from water glass molds has been extremely difficult because it requires the addition of a large amount of binder. It's Kade.

When manufactured using the above-mentioned microwave heating mold making method using recycled gold dust recycled by each of the above methods and containing a Kabuki-based binder, such as water glass, the cast product will suffer from burning and the appearance of the cast surface will change. There is also the problem that it is inferior. Furthermore, in the recycled sand obtained by each of the above methods, most of the clay content, which serves to moderate the thermal shock that the mold receives when pouring molten metal, disappears, so there are problems in terms of quality. be.

The present invention has been made in view of the above circumstances, and as a result of intensive research by the present inventors, it was found that the molding process II' (after properly crushing and sieving the sand, A rotating agitator is installed, and the JIY sand is dry washed in the rotating container.

After that, by classifying and recycling, even if 0.5 to 3φ and a small amount of binder-free binder is added to the recycled sand obtained in this way, it is irradiated with microwaves and heated to harden. The molds manufactured using this process have superior mold strength (resistance pressure) and the same or better surface stability than those using new sand, and the cast products do not seize and the casting surface is smooth. They discovered that it has an excellent appearance and have completed the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, the high sand generated after molding, pouring molten metal, and breaking the frame is subjected to appropriate treatments such as magnetic separation and cooling according to conventional methods to obtain recovered sand. This recovered sand is then subjected to the regeneration treatment according to the present invention. An example of the process is shown in FIG. That is, the lump-like recovered sand is crushed by a crusher (for example, Shaw, Crusher), and then sieved by, for example, a rotary 3 clean, and coarse particles are crushed by, for example, an impeller breaker.
It is crushed and sieved again. The recovered sand thus crushed and sieved is then dry cleaned using a scrubbing device having a special structure. The recovered sand fed into the scrubbing equipment is
It is preferable that the amount of pulverization and sieving is adjusted to 8 meshes or less depending on the process. The dry-washed recovered sand is then subjected to a classifier (?a powder removal) to remove fine powder, preferably 280 mesh or less, to obtain recycled sand.

FIGS. 2 and 3 show an example of one embodiment of the scrubbing device. Reference numeral 1 denotes a rotating container inclined at approximately 15 degrees, and the entire circumference of the bottom plate 3, which can be opened and closed, is rotated at a medium speed in the direction of the arrow shown in FIG. 2 by a driving device 2. An agitator 4 is disposed at a predetermined position within the rotary container I, and the agitator 4 is driven by a drive device 5 to move approximately 500 m in a direction opposite to the rotational direction of the rotary container I.
It is rotated at a high speed of 00 to 2000 rpm. A hopper 6 and a duct 7 are arranged at predetermined positions in the upper part of the rotating container l. Note that since the recovered sand contains clay, it tends to adhere to the inner wall of the rotating container 1. Therefore, the scraper 8 is moved to the bottom surface of the rotating container I so as to peel off the recovered sand that has adhered to the bottom surface and the inner peripheral wall of the rotating container 1. Alternatively, it is desirable to arrange it so as to be in sliding contact with the inner circumferential wall.

The agitator 4 shown in the figure also has a plurality of protrusions 9 around it.
It is a rotating disk having a shape, and has a shape in which a plurality of pins 10 are fixed to the upper and lower sides of the j-side part, but the design of the stirring blades, etc. can be changed as appropriate.

Here, the collected sand is put into the rotating container i from the hopper 6, and while being circulated by the rotation of the rotating container 1, it is subjected to an impact friction effect by the agitator 4 rotating at high speed in the opposite direction, and further rubs the sand grains together. The scrubbing process is performed by The regeneration process is usually carried out for several minutes to several tens of minutes, and the deposits on the surface of the sand grains are appropriately removed. The scraping regeneration time can be changed appropriately depending on the properties of the recovered sand. After the regeneration process, the bottom plate 3 disposed at the bottom of the rotating container 1 is opened and the regenerated sand is recovered. Fine powder is generated during the regeneration process, and this fine powder is removed by suction from the duct 7.

As shown in the figure, it is preferable that the rotating container 1 is inclined to some extent because the recovered sand undergoes a combined circulation movement in the circumferential direction and the radial direction, so that the scrubbing process is performed more effectively.

Further, as shown in the figure, when the axis of the agitator 4 is disposed at a position slightly displaced from the center of the rotating container 1, the scrubbing effect on the recovered sand is more effective.

By recycling in this manner, recycled sand having the optimum properties as raw material sand for microwave curing can be obtained.

The foundry sand recycled according to the present invention includes silica sand, zircon sand, alumina sand, mullite, etc., recovered sand from molds made with inorganic binders (sodium silicate, potassium silicate), and other dielectric materials with about 0. Recycled sand from casting lines or collected sand containing more than 3% of clay and less than 7% of clay.

The recycled sand obtained as described above is then mixed with an inorganic binder, preferably 0.5 to 3 g of water glass, and a small amount of water as needed, and then mixed with a kneader etc. for an appropriate time. By kneading, microwave curable sushi sand is obtained.

Next, the effects of the present invention will be explained in more detail with reference to Examples.

EXAMPLE Sand recovered from a low water glass mold (water glass addition amount: 2 g) made by microwave heating was repeatedly cast and regenerated twice using the regeneration system shown in FIG. In addition,
The rotational speed of the rotating vessel is 77 rpm; the rotational speed of the agitator is 1500 rpm.

1M recycled sand, 100 parts each of new sand and recovered sand for comparison were mixed with 2 parts of water glass, mixed well, a test piece of 50φ x 5011mm was made, and it was irradiated with microwaves of 245071fHz x 6RJP'. The mold strength (resistance pressure) was measured.

The results are shown in FIG. In addition, in the figure, each symbol -: indicates the following meaning (sand used).

A: Flattery new sand B: 1st time recovered sand (recovered original sand, unregenerated) C: 1st time recovered sand ff: 5 minutes recycled sand = 1st time recovered sand 10 minutes recycled sand E: 2nd time Recovered sand (unregenerated) F: Sand obtained by regenerating the sand recovered for the second time for 10 minutes As is clear from Figure 4, the strength of the next mold using the recycled sand recycled according to the present invention is greater than the strength of the second mold after 5 minutes of scrubbing. It can be used as recycled sand within 10 minutes and can be used as recycled sand within the above processing time.

Next, FIG. 5 shows the surface stability of molds using each of the above-mentioned sands. Incidentally, the surface stability was measured by the rotatub method, and the meaning of each symbol is the same as above.

As is clear from FIG. 5, the surface stability of the mold using the recycled sand according to the present invention is equivalent to that of new sand after 5 and 10 minutes of scrubbing, and the surface stability of the mold using the recycled sand is equivalent to that of new sand. properties are obtained.

Using the foundry sand recycled by the recycling system of the present invention, an inorganic binder is mixed and kneaded, a core is manufactured by a core molding method using microwave heating, and this is used to cast the molding sand. However, it was confirmed that the cast product had no embroider marks and had an excellent casting surface.

As described above, the recycled sand recycled by the recycling system according to the present invention can be effectively used in the mold manufacturing method using the microwave heating method, and can be used to create molds with excellent mold strength and surface stability.
, can be created. Moreover, the products cast by this method do not have any printing marks and have an excellent cast surface appearance. Moreover, the regeneration treatment according to the present invention does not require water washing, drying treatment, or high temperature roasting treatment as in conventional methods, and a large amount of reusable quality regenerated sand can be obtained by dry scrubbing treatment. The energy cost required for regeneration can be reduced, and the regeneration cost is reduced to about half that of conventional methods. Further, since any type of high sand can be used as the waste sand that can be used in the present invention, it is advantageous from the viewpoint of resource saving.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing an example of the regeneration process of the present invention, Fig. 2 is a partial sectional view schematically showing a scrubbing device, Fig. 3 is a view taken along the line A-A in Fig. 2, and Fig. 4 shows various FIG. 5 is a graph showing the strength of a mold manufactured using foundry sand, and FIG. 5 is a graph showing its surface stability. 1 is a rotating container, 4 is an agitator, 16 is a hopper, 7 is a duct), and an 8U scraper. Applicant Komatsu Ltd. Representative Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto Figure 2 Figure 3 Microwave heating 1 minute (seconds)

Claims (1)

[Claims] After appropriately crushing and sieving the mold recovered sand, the recovered sand is dry washed in a rotating container equipped with an agitator that rotates in the opposite direction to the rotating direction of the rotating container, and then classified. A method for recycling sand recovered from molds.