JPH10193031A - Molding sand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove a molding sand from a product with acid solution by crushing an exoskelton being industrial waste and using an aggregate obtained by screening the exoskelton as the raw material of the molding sand for core. SOLUTION: The exoskelton of oyster, scallop, etc., discharged from a fishery processing plant or the exoskeleton of a pearl oyster discharged from a pearl manufacturing plant is heated at about 600 deg.C in a rotary kiln 1 and organic material of adductor muscle, etc., stuck to the exoskelton α and burnt and removed. The burning-treated exoskelton is crushed by a crusher 2. The size of the crushed grain diameter is adjusted so that a lot of the aggregates having the grain diameter for the normal molding sand are obtained. In the scanning, two kinds of the sieves 3 are used. The burnt and crushed exoskeleton is passed through the sieve having sieve opening of the large limit of the grain size in the allowable grain size distribution as the molding sand and the passed material as screened with the sieve having the small limit in the allowable grain size distribution. The screened material of plus sieve is used as the aggregate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding sand, and more particularly, to molding sand suitable for core molding sand.

[0002]

2. Description of the Related Art Conventionally, river sand and mountain sand containing silicic acid (SiO2) as a main component have been used as this type of foundry sand. Among the foundry sands, those containing almost no viscosity, such as silica sand, river sand or beach sand, are used as synthetic sand artificially mixed with binders such as Kibushi clay and other substances. Mountain sand and the like that are contained to some extent are used as natural sand as they are.

[0003] Casting sand for cores used for manufacturing cores, so-called core sand (hereinafter referred to as "core sand"), can withstand the pressure of the molten metal, and has shrinkability, fire resistance. sex,
Because it is required to have excellent air permeability, it is examined more than molding sand for molds. A core is usually manufactured using the examined core sand by a shell mold method, a cold box method, or the like.

[0004]

In recent years, however, there has been a problem that core sand has been difficult to remove from cast products due to thinning of the casting. For example, when the core is a shell core, the amount of heat received by the core during casting due to thinning of the casting is small, and the ratio of the unburned synthetic resin of the binder contained in the core is large, and therefore, the core collapses. And the core sand is difficult to remove from the cast product.

[0005] In addition, shellfish are generated in large quantities as waste from fishery processing plants that use shellfish as a raw material. Some of these wastes are used as biological carriers for water treatment, but most of them are disposed of as landfills without being effectively used.

By the way, the main component of the shell is calcium carbonate (CaCO3), and it has been desired to develop a new application utilizing these properties.

Accordingly, the present invention has been made to meet the above-mentioned demand, and an object of the present invention is to provide a molding sand which can be easily removed from a casting product by using shells of industrial waste.

[0008]

In order to achieve the above object, the foundry sand according to the present invention is characterized by using an aggregate obtained by crushing and sieving shells as a raw material.
Further, the molding sand is for a core.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a process chart for manufacturing a molding sand according to one embodiment. Hereinafter, description will be made in the order of steps.

(A) Incineration process Shells A are shells such as oysters and scallops discharged as industrial waste from marine processing plants, or pearl oysters discharged as industrial waste from a pearl manufacturing plant. Lee
It is mainly composed of CaCO3.

[0011] This shell b is 60 in rotary kiln 1
Heated to about 0 ° C., the organic matter such as the scallop attached to the shell b is incinerated and removed. Although the incinerator in this incineration process is performed by the rotary kiln 1, other types of incinerators may be used.

B) Pulverization Step The incinerated shell A is pulverized by the crusher 2. The size of the particle size to be pulverized is adjusted so that a large amount of aggregate having a particle size of ordinary molding sand can be obtained in the sieving step described later.
That is, the powder is adjusted so that the degree of pulverization is not excessive and the amount of powder does not increase, and the degree of pulverization is too small and does not remain on the sieve.

Although the crusher 2 uses a mortar type, various types such as a ball mill type, a fret type and a crushing roll type can be adopted.

(C) Sieving process The crushed material A 'crushed by the crusher 2 is separated by using the sieve 3 so as to have a known particle size of foundry sand.

FIG. 1 shows that one aggregate 3 serving as casting sand is separated by one sieve 3, but in actuality, the aggregate is separated using two types of sieves. First, it is passed through a sieve with a larger particle size distribution, which is acceptable as foundry sand,
The passed-through material is sieved with a sieve having an opening having the smaller particle size distribution, and the separated material remaining on the sieve is used as aggregate B.

The aggregate obtained as described above is used as foundry sand. That is, after coating the foundry sand with a known binder, a mold (mother) and a core are manufactured. In particular, the core is manufactured into a core having predetermined strength and the like by using a known shell mold method, a cold box method, and the like, using the obtained aggregate as core sand.

The foundry sand obtained as described above can be easily removed from the cast product after casting. That is, since the main component of the foundry sand obtained as described above is calcium carbonate, when the casting product is immersed in an acid solution, the foundry sand adhering to the casting product is dissolved and removed from the casting product. .

In particular, there is a feature that even a molding sand adhering to an inner space of a casting product such as a core can be easily removed by an acid solution.

When the casting is made of aluminum (including aluminum alloy), the use of nitric acid as the acid solution makes it possible to remove molding sand (core sand) without adversely affecting the casting.

[0020]

The foundry sand according to the present invention crushes shells,
Since the aggregate obtained by sieving is used as a raw material, casting sand that can be easily removed from a casting product with an acid solution can be obtained. Also, since it is made from shells,
Industrial waste can be effectively used.

Further, when the molding sand is used for the core, the removal of the core sand particularly in the inner space of the casting can be easily performed by using the acid solution.

[Brief description of the drawings]

FIG. 1 is a process diagram for producing a molding sand according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Crusher 3 Sieve i Shell i 'Crushed material b Aggregate

Claims (2)

[Claims] 1. A foundry sand characterized by using an aggregate obtained by crushing and sieving shells as a raw material. 2. The molding sand according to claim 1, wherein the molding sand is for a core.