JPH02247492A - Aluminum melt storage tank - Google Patents

Abstract

PURPOSE:To assure stable operation of a title tank in 1 to several weeks by inserting the tank, in which a ceramic film layer, an aluminum-resistant refractory plate, and a thermal insulation plate are laminated on the outer peripheral surface of an SiC bus into the inside of a low temperature heat insulation plate having inner lining in an outer box, and permitting porous granular refractory and the like to intervene between said tank and said low tempera ture heat insulation plate. CONSTITUTION:A ceramic fiber blanket and a ceramic fiber layer 2 are disposed on the outer peripheral surface of an SiC bus 1. The outer periphery is surrounded by an aluminum resistant refractory plate in which fibrous wollastonite is blended. A high temperature heat insulation plate 4, which is yielded by heating a calcium silicate to completely remove crystal line water and free water, is mounted on and assembled in the outer peripheral surface of the aluminum refractory late 3 through a threaded nail. On the other hand, refractory heat insulation bricks 8 are distributed and disposed on the bottom of a steel plate outer box 7, among which a low temperature heat insulation plate 6 comprising a pearlite board is disposed and also mounted on the side of the outer box. Further, an SiC bus 1, on an outer peripheral surface of which the high temperature heat insulating plate 4 is mounted, is inserted into the interior of the low temperature heat insulation plate 6, and a porous granular refractory is intervened between it and the low temperature heat insulation plate 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Bone Nail] The present invention relates to a storage tank for holding molten aluminum and aluminum alloy.

[Conventional technology]

In order to cast aluminum or aluminum alloys by a low-pressure casting method or the like, the molten metal is stored in a storage tank, and the molten metal is guided from the storage tank to a mold using a pipe or the like to perform casting. There are two types of storage tanks: one that heats the molten metal in the tank with an electrode inserted through a lid attached to the tank and maintains the temperature of the molten metal, and another that uses heating wires attached to the inner surface of the lid of the tank to heat and keep it warm. .

Conventionally, the bath that comes into direct contact with the aluminum or aluminum alloy of this storage tank has been formed by mixing refractory castable by adding 5 to 30 parts by weight of water to 100 parts by weight of refractory castable and pouring it into a mold, or It was formed by assembling silicon carbide tiles bonded with silicon nitride as a binding material using mortar, and filling the gap with the insulation material on the outside with refractory material.

Most of the water used in construction is removed by drying before use. However, the outside is sealed by an outer box made of wood, and the molten metal can only be dried from the inside, so even if heated and dried for a long time, it cannot be removed and moisture remains. This moisture gradually permeates into the molten aluminum during operation, increases the H gas concentration in the molten aluminum, and causes pinholes and the like to occur in the cast product, deteriorating the product yield. It took several months for this moisture to disappear and the product yield to stabilize.

[Problem to be solved by the invention]

An object of the present invention is to solve the above problems and provide a molten aluminum storage tank that can provide a stable product yield from the start of use.

[Means to solve the problem]

The present invention relates to an SIC bus consisting of a bus-shaped integral sintered body of silicon carbide bonded with silicon nitride as a binder, a ceramic fiber layer applied to the outer peripheral surface of the sla lotus, and a free bonding layer applied to the outer peripheral surface of the ceramic fiber layer. An aluminum fireproof board that does not contain moisture or water of crystallization, a high-temperature insulation board that does not contain free moisture or water of crystallization applied to the outer peripheral surface of the aluminum fireproof board, and porous granules applied to the outer peripheral surface of the high-temperature insulation board. refractories,
It comprises at least one of ceramic fiber bulk, glass fiber bulk, and sand, a low-temperature insulation board applied to the outer periphery of the porous granular large-sized material, etc., and an outer box applied to the outer periphery of the low-temperature insulation board. A molten aluminum storage tank is used as a means to solve the problem.

[Effect]

A sintered body of silicon carbide bonded with silicon nitride as a binding material is
It is a well-known material used as an industrial material for shelf boards for ceramic firing furnaces, pots, protective tubes for heating wires, tap holes for aluminum, and others. This material is used as a bath-shaped integral sintered body because it is not wetted by molten aluminum and is not attacked by flux.

This material has a coefficient of thermal expansion of 4.6 x 10 = cr
Since ry'crry'σ is relatively large, a ceramic fiber layer is provided on its outer peripheral surface to absorb impact and thermal expansion.

However, if a crack occurs in the SIC bus, the ceramic fiber layer cannot prevent molten aluminum from leaking outward, so the outer peripheral surface of the ceramic fiber layer is covered with an aluminum fireproof plate that does not contain free moisture or crystallized water. surround.

This aluminum fireproof plate contains high alumina cement in a weight ratio of 35 to 65:65 to 35, as proposed in JP-A No. 60-226438. have a specific surface area of 4,000 to 5,000 cm and 7 g according to the Blaine method,
8,000-10,000 Cm 7g of 3-6:4 weight ratio, and 0.1-0.5 parts by weight of organic binder and 40-40 parts of water per 100 parts by weight.
It is preferable to use a product containing no crystal water or free moisture, which is obtained by adding 50 parts by weight, molding, drying, and firing at about 800σ. Since fibrous wollastonite does not have crystallization water, completely water-free refractories can be easily obtained, and SIC
Even if cracks occur in the bath, moisture can be prevented from penetrating into the molten metal. This fired product has a high alumina content in its chemical composition, so it has corrosion resistance against aluminum.

However, since a high alumina composition containing no free water or water of crystallization has aluminum resistance, other compositions may be used.

SIC buses and aluminum fireproof boards have low insulation properties, so
It is necessary to surround the outer periphery with heat insulating boards for high temperatures and heat insulating boards for low temperatures.

As the heat insulating board for high temperatures, a calcium silicate heat insulating board of No. 1181 which has been heated to completely remove crystal water and free moisture may be used. Alternatively, a ceramic fiber board may be used, although it is more expensive.

Perlite board can be used as a low-temperature insulation board.

In order to make these strong, an outer box made of M board is required. However, when these are arranged one after another inside the outer box, a gap is created between the layers, and the load of the molten metal placed inside is concentrated in this gap, causing cracks to occur in the bath.

Therefore, in the present invention, a low-temperature insulation board is arranged inside the outer box, and a ceramic fiber layer, an aluminum fireproof board, and a high-temperature insulation board are separately attached to the outer peripheral surface of the SiC bus. Insert into the plate and fill the spaces between the two with materials that can be packed densely, such as porous granular refractories, ceramic fiber bulk, glass fiber nomark, castings, sand, etc., and assemble them inside the outer box without any gaps. It was designed so that

High-temperature fireproof plates and low-temperature fireproof plates can be assembled with screws, etc., so they are assembled on the outer periphery of the SiC bus and the inner periphery of the outer box, respectively, and then fitted together and filled with porous granular refractories or ceramic fiber bulk in the gap between them. By filling the glass fiber bulk 1 with silica sand and foundry sand, these members can be assembled without creating gaps between them.

As the porous granular refractory, a granular foam of a heat-expandable mineral such as shale or obsidian, or a refractory powder containing air bubbles and fired into small spheres may be used.

〔Example〕

An embodiment of the molten aluminum storage tank according to the present invention shown in the drawings will be described.

The SIC bus 1 has a rectangular shape with an inner long side of 1396 mm, a short side of 950 mm, a depth of 370 W, and a thickness of 40 mm. A ceramic fiber blanket with a free thickness of 6 mm is arranged on this outer peripheral surface to provide a ceramic fiber layer 2, and the outer periphery is coated with the above-mentioned fibrous wollastonite to a thickness of 50 f.
It was surrounded by an aluminum fireproof board 3. A No. 1181 calcium silicate heat insulating board is placed on the outer peripheral surface of the aluminum fireproof board 3, and a high temperature heat insulating board 4 which has been heated to completely remove crystal water and free moisture is heated so that the ceramic fiber layer 2 is approximately 1 mm thick. It was compressed and assembled with screws and nails. Inside long side 185
6m, short side 1410mm, depth 600m5. Inside the outer box 7 made of a 22 mm thick steel plate, 35 m5 thick fireproof and insulating bricks 8 are distributed at the bottom to support the load from above, and between them are 35 mm thick perlite boards. A low-temperature heat insulating board 6 consisting of the following was laid down, and the same low-temperature heat insulating board 6 was attached to the sides.

Approximately 35 mm on the bottom low-temperature insulation board 6 and fireproof insulation brick 8
Spread artificial porous granular refractory material 5 uniformly to the thickness of fi,
On top of that, insert the assembly up to the high-temperature insulation board 4 on the outer peripheral surface of the SiC path 1, and fill the gap of approximately 35 m created between the surroundings and the low-temperature insulation board 6 with porous granular refractory material. The storage tank was completed.

After heating this tank to 800σ over 3 days,
When we poured 0C aluminum molten metal and kept it at that temperature for one week, and then measured the changes in the H gas concentration in the aluminum molten metal over a period of -1 week, we found that there was almost no change in the H2 gas concentration, and we were able to produce aluminum castings with a good yield. It turns out that it can be manufactured. Note that the temperature of the outer surface of the outer box 7 was approximately 80σ.

〔Effect of the invention〕

With conventional molten aluminum storage tanks, not only does it take a long time to dry, but it also takes two to three months from the start of use to stable operation depending on the size, and repairs are required after three to six months. However, the molten aluminum storage tank of the present invention enables stable operation within one to several weeks, and can be used for several years without requiring repairs, and does not require the use of castables or mortar. Since there is no such thing, it can be disassembled and repaired easily.

[Brief explanation of drawings]

The drawing is a sectional view of one embodiment of the molten aluminum storage tank of the present invention. 1. SiC bus 2. Ceramic fiber layer 3. Aluminum fireproof board 4. High temperature insulation board 5. Porous granular refractory 6. Low temperature insulation board 7. Outer box 8. Fireproof insulation Brick Applicant Isolite Kogyo Co., Ltd. Topie Kogyo Co., Ltd. Procedural Amendment Heisei-ll=1W1 Patent Application No. 65246 Title of Invention Relationship to the Aluminum Molten Metal Storage Tank Amendment Case Patent Applicant Name Address Dojimahama, Kita-ku, Osaka 1-2-6 Name: Inlight Kogyo Co., Ltd. Agent address: 1-12-15, Shinjuku, Shinjuku-ku, Tokyo Number of inventions increased by amendment Procedural amendment (voluntary) Indication of case Heisei! Title of the invention 3. Patent application filed in the year related to the case of the person making the amendment: Aluminum molten metal storage tank

Claims (2)

[Claims] (1) An SiC bus consisting of a bus-shaped integral sintered body of silicon carbide bonded with silicon nitride as a binder, a ceramic fiber layer applied to the outer peripheral surface of the SiC bus, and free moisture applied to the outer peripheral surface of the ceramic fiber layer. and an aluminum fireproof board that does not contain crystallization water, a high-temperature insulation board that does not contain free moisture or crystallization water, and a porous granular fireproofing board that does not contain free moisture or crystallization water, which is applied to the outer peripheral surface of the aluminum fireproof board. at least one of a material, ceramic fiber bulk, glass fiber, bulk, and sand, a low-temperature insulation board applied to the outer periphery of the porous granular refractory, etc., and an outer box applied to the outer periphery of the low-temperature insulation board. Aluminum molten metal storage tank with (2) The molten aluminum storage tank according to claim 1, wherein the aluminum fireproof plate has a composition of fibrous wollastonite and high alumina cement in a weight ratio of 35 to 65:65 to 35.