JP2002309320A - Flux for treating molten aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux for treating molten aluminum alloy, utilizing sludge consisting essentially of aluminum fluoride by-produced in a large quantity when a phosphate treatment is applied in an undercorting treatment of an exterior material for a car body. SOLUTION: This flux for treating the molten aluminum alloy is composed of 30-90 mass% metallic halide, <=49 wt.% inorganic salt, 1.0-10 mass% metallic phosphate (0.2-2.0 mass% as P content) while limiting the total of the inorganic salt and the metallic phosphate to <=50 mass%, and the balance inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for melting an aluminum alloy used in a process of melting recovered scrap to recycle it into a useful secondary alloy or casting alloy when recycling the aluminum alloy material. For flux.

[0002]

2. Description of the Related Art Aluminum or an aluminum alloy (hereinafter referred to as an aluminum alloy) has been generally recycled from the viewpoint of resource saving and cost reduction. However, since the content of the additional element differs depending on the alloy type, it is recycled as a secondary alloy or a cast alloy whose component composition can be easily adjusted.

[0003] Specifically, the recovered scrap is converted into a secondary alloy or a cast alloy through steps such as melting, smelting, slag removal and casting. The steps from melting to slag removal will be described in detail. That is, the raw material charged into the melting furnace is heated and melted to form a molten metal. Next, after performing degassing treatment and inclusion treatment, a halogen-based refining agent, for example, chlorine gas or flux is blown into the molten metal. In this refining process, organic substances and the like attached to the raw material scrap in the melting process become various inclusions together with oxides generated during melting, and these float as slag in a mixed state with the metal component by the action of the refining agent. . This slag is a major cause of product defects and should be removed.However, if a large amount of metal is contained and is removed as it is, metal loss will occur. It is necessary to remove only things efficiently.

[0004] As a typical method for this purpose, a halogen-based flux is sprayed on a molten metal surface and mixed with the slag to react with fine Al in the slag. A method is known in which the fluidity of the metal is increased by heating to return the metal to the molten metal. It is also well known that this kind of flux is blown into the molten metal together with an inert gas such as nitrogen or argon gas during the degassing process.

[0005] Such degassing and slag removal from the molten metal is extremely important as a molten metal treatment for purifying the molten metal and improving product quality, and various fluxes have been proposed. In particular, as a flux for treating an aluminum alloy molten metal, for example, JP-A-7-207376 and JP-A-1
No. 1-80851, and the like.

On the other hand, in the automobile industry, aluminum alloys are frequently used for various members from the viewpoint of weight reduction. In particular, the exterior body (panel material) of an automobile body is composed of a steel plate portion and an aluminum alloy plate portion. Many. Then, such an exterior portion is painted, but is generally subjected to a zinc phosphate treatment as a base treatment. However, since the steel plate portion and the aluminum alloy plate portion are simultaneously processed during the zinc phosphate treatment, aluminum ions are gradually increased in the treatment liquid, and the treatment property for the steel plate is deteriorated, which is prevented. To do so, it is known as a general technique to precipitate aluminum ions by adding fluorine ions.

However, according to this method, although the zinc phosphate treatment performance is improved, there is a problem that a large amount of sludge mainly containing precipitated aluminum fluoride is generated. In addition, this sludge is difficult to reuse because of its high fluorine content, and there is a problem that it must be disposed of as landfill at present.

[0008]

Therefore, the present inventors examined the composition of the sludge in order to make effective use of the sludge, and found that cryolite (Na ₃ AlF ₆ ), which is the main component of the flux for treating molten aluminum alloy, was used. It was found that a large amount of elements common to the above were contained, and various experiments were conducted on the possibility of use as a flux raw material.

That is, in the experimental example, a test piece having a steel material: aluminum alloy material area ratio of 2: 1 was used for free fluorine 4
The sludge generated by phosphate treatment at 00 ppm and the water removed was mixed with an existing flux and used as a flux for molten metal treatment. The composition of this sludge was as shown in Table 1. In the component analysis, the sludge was dried at 105 ° C. for 2 hours, and then 0.5 g was collected and dissolved in 30 cc of concentrated hydrochloric acid by heating to obtain 100 cc.
The metal components were measured by atomic absorption spectrometry, and the other components were measured by ion chromatography. Table 2 shows the component composition of the existing flux, for example, the flux-A of Fountech Co., Ltd. as an example.

[0010] As can be seen from the component compositions in these tables, sludge can be used as part of the fluoride and metal phosphate component feedstock in the flux.

[0011]

[0012]

Therefore, in order to examine the effect of the addition of sludge on the flux characteristics, 5%, 10%, 15%, 20%, and 25% of sludge were added to the flux-A.
When the melting point change and fluidity were examined at the level,
The result is shown in FIG. From this result, it can be understood that the melting point of the flux increases with an increase in the amount of sludge added, the fluidity decreases, and slag formation tends to deteriorate. It was determined that they could be added until. That is, the fluidity can be dealt with by devising the supply method, but if the slag becomes worse, the original function of the flux cannot be achieved.

[0014] Next, the influence of the addition of sludge on the contamination of the molten metal by the impurity metals in the sludge was examined by examining the changes in the contents of Fe, Zn, and Na. As shown in Table 4, the contamination of the molten metal was almost negligible and negligible. .

[0015] The test conditions were as follows.

Flux: 2 levels of no sludge addition and 20% addition of sludge Ingot used: 99.99% pure aluminum ingot Test conditions: 5 kg of molten metal, temperature of molten metal 740 ° C. Flux adding method: wrapped in high purity aluminum foil Immersion in molten metal Analytical method: A part of the molten metal before and after the addition of flux was sampled, and impurity elements were analyzed by emission analysis.

[0017]

The structure of the present invention which has achieved the above objects is as follows. That is, in the first invention, the metal halide is 30 to 90% by mass, the inorganic salt is 49% by mass or less, the metal phosphate is 1.0 to 10% by mass (the content of P is 0.1 to 10% by mass). 2 to 2.0% by mass), and the total amount of the inorganic salt and the metal phosphate is limited to 50% by mass or less,
A flux for treating an aluminum alloy melt, the remainder being made of unavoidable impurities.

A second aspect of the present invention is a flux for treating an aluminum alloy molten metal, which contains 50% by mass or less of an inorganic oxide and / or a carbonaceous substance in addition to the above components.

According to a third aspect of the present invention, in the first or second aspect, the metal phosphate is Fe, Zn, Mn, Ni, A
It is made of one or more of metal phosphates selected from 1, Na, and K.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the flux for treating an aluminum alloy molten metal according to the present invention, a metal halide is decomposed and gasified in the molten metal, and hydrogen gas is diffused in bubbles to remove and float or remove slag. The exothermic reaction facilitates the separation of the slag and the molten metal. For example, LiF, Na
F, KF, SrF, CaF ₂ , MgF ₂ , AlF ₃ , N
aAlF ₄ , Na ₃ AlF ₆ , KAlF ₄ , K ₃ AlF ₆
Such as fluorine-based halogen, NaCl, KCl, SrC
_{l, CaCl 2, MgCl 2,} BaCl 2, AlCl 3
And the like.

Inorganic salts and metal phosphates act as combustion aids to generate heat during the treatment of the molten metal. As inorganic salts, for example, metal carbonates (Na ₂ CO ₃ , K ₂ CO ₃ , M
gCO ₃ ), metal sulfates (Na ₂ SO ₄ , K ₂ SO ₄ ,
MgSO ₄ , metal nitrates (NaNO ₃ , KNO ₃ , C
a (NO ₃ ) _{2 and the} like. The metal phosphate is, for example, FePO ₄ , Zn ₃ (PO) ₂ , Mn ₃ (PO) ₂ ,
Ni ₃ (PO) ₂ etc.).

If the inorganic salt and the metal phosphate are contained in excess, the amount of slag produced is excessive.
% Or less, and the metal phosphate is set to 10% or less in consideration of the blowing resistance of the flux.

The inorganic oxide is used as a modifier or an extender for appropriately controlling the reaction during the treatment of the molten metal with respect to the above-mentioned composition, and examples thereof include MgO, SiO ₂ , and Al ₂ O _3. .

[0024] The carbonaceous substance can be optionally used as a combustion aid similarly to the above-mentioned inorganic salts, and coke, pulverized coal and the like can be used.

The above-mentioned flux composition is sprayed or pressed as a powder on the surface of the molten metal at the time of use, is injected into the molten metal together with an inert gas such as nitrogen by a blowing pipe, or is formed into a molten solid as a molded solid. It is preferable to appropriately select the method of pushing in according to the type and capacity of the furnace. In the case of a powder, the particle size is appropriately adjusted so as to conform to these usage methods, and in the case of a solid, the powder is appropriately molded into a shape and size.

[0026]

Embodiments of the present invention will be described below.

[0027] Using a mixture with the sludge flux having the composition and properties shown in Table 5 above, a blowing test was performed in an actual furnace, and blowing properties, slag separation properties, and slag properties were examined. Table 6 shows the results. The flux was mixed with sludge and blown together with nitrogen gas into a 15-ton melting furnace using a feeder.

[0028] From this result, the sludge is 20% of the flux amount
It was confirmed that it could be used up to.

Therefore, a mixture of the existing flux and sludge added at 20% is defined as a total flux amount.
Attempts were made with other existing fluxes based on this, with similar results.

Next, the degassing effect of the molten metal and the contamination status of impurities were examined. As shown in Table 7, there was almost no difference from the flux of the conventional product, and the value was negligible.

[0031] The present invention has been created based on the above experimental results,
The aim is to provide a flux for treating aluminum alloy molten metal that has the same performance as conventional products even when using sludge generated when simultaneously treating steel and aluminum alloy with zinc phosphate as a part of the raw material. Is what you do.

[0032]

According to the present invention, the sludge generated by the phosphate treatment of an aluminum alloy can be used as a flux for molten metal processing, and it can be used sufficiently without any significant difference in performance from a conventional flux. It is. As a result, it is possible to achieve sludge recycling that has hardly been used until now.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Fujimoto 15 Kinuigaoka, Moka-shi, Tochigi Pref. Inside Kobe Steel Moka Works (72) Inventor Ryoji Masada 1-5-1, Takatsukadai, Nishi-ku, Kobe-shi, Hyogo 5 Kobe Steel, Ltd. Kobe Research Laboratory (72) Inventor Yoshiko Ogawa 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. (72) Inventor Tadashi Mariya 3-chome Marunouchi, Chiyoda-ku, Tokyo No. 3-1 Within Fountech Co., Ltd. (72) Inventor Tadao Meguro 2611-12 Kitano, Moro, Kanuma-shi, Tochigi F-term within the Fountech Tochigi Research Laboratories Co., Ltd. 4K001 AA02 EA04 KA08

Claims (3)

[Claims] 1. A metal halide in an amount of 30 to 90% by mass.
And an inorganic salt of 49% by mass or less and a metal phosphate of 1.0 to
10% by mass (P content: 0.2-2.0% by mass), the total amount of inorganic salts and metal phosphates is limited to 50% by mass or less, and the balance consists of unavoidable impurities. A flux for treating molten aluminum alloy, characterized by the following features. 2. The flux for treating molten aluminum alloy according to claim 1, further comprising a total of 50% by mass or less of an inorganic oxide and / or a carbonaceous substance. 3. The method according to claim 2, wherein the metal phosphate is Fe, Zn, Mn,
The flux for treating an aluminum alloy molten metal according to claim 1, comprising one or more of phosphates of a metal selected from Ni, Al, Na, and K. 4.