JPS59104441A - Preparation of ca-al alloy - Google Patents

Abstract

PURPOSE:To prepare a Ca-Al alloy in good electrolytic efficiency by performing the molten salt electrolysis of CaCl2 in the presence of molten Al by using an electrolytic bath containing calcium chloride and alkali metal halide of which the wt. ratio is prescribed with respect to calcium chloride. CONSTITUTION:An electrolytic bath containing calcium chloride and alkali metal halide in an amount of 3/2 times or more, especially, 4/1 times or more with respect to calcium chloride is prepared. In this case, as calcium chloride, a salt reduced in water of crystallization or anhydride is pref. used. In addition, as alkali metal halide, chloride is preferred and, especially, LiCl is most pref. In electrolysis, an electrolytic cell having the electrolytic bath charged thereinto and having an anode at the upper part thereof while a cathode at the lower part thereof is used and calcium chloride is electrolyzed in the presence of molten Al. By this method, formed Ca is dissolved in molten Al present at the bottom part of said cell while the obtained Ca-Al alloy is taken out from the bottom part of the electrolytic cell in a molten state. In addition, the electrolytic temp. is pref. 650-750 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a calcium-aluminum alloy (hereinafter referred to as Ca-At alloy) by molten salt electrolysis. More specifically, Ca-At, which efficiently performs molten salt electrolysis of calcium chloride in the presence of molten aluminum,
This invention relates to a method for producing an alloy.

Metallic calcium has conventionally been used for cleaning such as desulfurization and dephosphorization of molten iron. However, it has been difficult to handle metallic calcium because it spontaneously ignites in the air.

In order to compensate for the above-mentioned drawbacks, metallic calcium has recently been used in an alloy with metallic aluminum to improve safety. And as a method for manufacturing the above Ca-At alloy,
Molten salt electrolysis methods using molten calcium chloride as an electrolytic bath in the presence of molten aluminum are already known.

In this method, molten aluminum is placed on the cathode of an electrolytic cell that has an anode at the top and a cathode at the bottom, and electrolysis is carried out using molten calcium chloride as an electrolytic bath. -At alloy is collected.

However, according to this method, Ca-
The drawback is that the electrolytic efficiency of At alloys is poor.

As a result of repeated research to improve the shortcomings of the conventional production methods for Ca-At alloys described above, the present inventors discovered a method for producing corroded Ca-At with high electrolytic efficiency, and came to propose the present invention. Ta.

That is, the present invention provides a method for producing a calcium-aluminum alloy by carrying out molten salt electrolysis of calcium chloride in the presence of molten aluminum, the electrolytic bath containing an alkali metal 710 genide and calcium chloride, and This is a method for producing a calcium-aluminum alloy using an electrolytic bath in which the alkali metal halide has a weight ratio of V2 or more to calcium chloride.

The method of manufacturing the molten aluminum used in the present invention is not particularly limited, and it is usually sufficient to melt metal aluminum and use it.

Calcium chloride used in the present invention is an anhydrous salt.

Monohydrate, dihydrate, tetrahydrate, hexahydrate, etc. are used. Generally, when calcium chloride containing crystallization water is used, HCL gas is generated as soon as it is introduced into the electrolytic bath, and in order to prevent corrosion of the equipment and reduce ct2 purity, salts with less crystallization water or anhydrous salts are usually used. is preferred.

As the alkali metal chlorides used in the present invention, fugides, chlorides, bromides, and iodides of alkali metals such as lithium, sodium, and potassium can be used without any limitations.

Among these, chlorides are preferable, and lithium chloride is most preferably used since it also has a large additional effect of lowering the melting temperature of the electrolytic bath.

The electrolytic bath for molten salt electrolysis of the present invention consists of the above-mentioned calcium chloride and alkali metal halide.

Of course, a sixth component may be added as described later.

The main feature of the present invention is that the composition of the electrolytic bath is such that the weight ratio of the alkali metal chloride to calcium chloride is at least a specific value. That is, the electrolytic efficiency can be improved by setting the composition of the electrolytic bath to a high weight ratio of alkali metal - chloride to calcium chloride, more preferably 4/1 or more. It can be achieved. It is surprising that electrolytic efficiency can be improved by increasing the weight ratio of alkali metal chloride, which has traditionally been used as a flux, in the electrolytic bath to a certain value or more. It is.

The inventor conjectures that such an effect of the alkali metal 7-logenide is as follows. If the weight ratio of the alkali metal halide in the electrolytic bath is smaller than the above value, metallic calcium produced by electrolysis will be dissolved in the electrolytic bath. Metallic calcium dissolved in the electrolytic bath diffuses in the electrolytic bath and recombines with chlorine generated by electrolysis near the surface of the electrolytic bath. It is presumed that this causes the electrolytic efficiency to deteriorate.

It is believed that dissolution of metallic calcium into the electrolytic bath can be prevented by setting the weight ratio of the alkali metal no-loginide in the electrolytic bath to the above-mentioned value or more as in the present invention. As a result, it is thought that recombination of metallic calcium with chlorine can be prevented and electrolysis efficiency will be improved. In addition, the addition of alkaline metal chloride reduces the viscosity of the electrolytic bath, making it easier for ions to move. It is thought that the electrolytic efficiency is improved also for this reason.

The electrolytic reaction of the alkali metal chlorides used in the present invention starts after all of the calsila chloride L has been electrolyzed. Therefore, as long as calcium chloride is continuously replenished, no alkali metal will be contained in the Ca--At alloy, even though a large amount of alkali metal halide is used as described above. Therefore, alkali metal halides can be used continuously by simply replenishing losses due to evaporation, etc.

Since chlorine is generated in the electrolysis of the present invention, if the specific gravity of the Ca-At alloy produced is small, calcium in the Ca-C1 alloy may be removed during or after the alloy floats to the surface of the electrolytic bath. It may recombine with chlorine and reduce electrolytic efficiency. Therefore, when producing the Ca-At alloy, it is necessary to make the specific gravity of the Ca-A4 alloy larger than the specific gravity of the electrolytic bath so that the produced Ca-At alloy does not float near the surface of the electrolytic bath. preferable. For this, C
It is preferable that the calcium content in the a-At alloy is 35% by weight or less.

Furthermore, by doing this, the Ca-A4 alloy can be generated in the molten aluminum present at the bottom of the electrolytic cell, so the Ca-At alloy can be collected from the molten aluminum at the bottom of the electrolytic cell. This can be done by taking the part out of the electrolytic cell. As a result 1, Ca-, k
It becomes possible to collect L alloy. At this time, if the diffusion of calcium into the molten aluminum is slow, the Ca--At alloy generated near the surface of the molten aluminum floats because it has a high calcium content. Therefore, molten Ca-Ct
Preferably, the alloy layer is stirred to ensure a uniform calcium content.

In the present invention, it is preferable to add an alkaline earth metal compound to the electrolytic bath in addition to the above-mentioned alkali metal chlorides. By adding an alkaline earth metal compound, particularly a magnesium compound, it is possible to prevent clogging of the narrow part of the electrolytic cell due to precipitation of a part of calcium as a solid.

The conventional electrolytic cell with an electrode at the top and a cathode at the bottom can be used without any restrictions. Furthermore, the conventional electrolytic method can be used as is.

The electrolysis method according to the present invention will be explained below with reference to FIG. The electrolytic cell 1 has a carbon anode 2 at the top and an iron cathode 6 at the bottom. Electrolysis is carried out by making molten aluminum 4 exist on the cathode 3 at the bottom of the electrolytic cell 1, and by making an alkali metal chloride and calcium chloride present in the above-mentioned weight ratio as the electrolytic bath 5. Calcium generated by electrolysis is dissolved in the molten aluminum 4 at the bottom of the electrolytic cell 1, and Ca -
An AL alloy is obtained. The produced Ca-At alloy is taken out in a molten state from the Ca-At alloy take-out port 6 at the bottom of the electrolytic cell. Calcium chloride is replenished depending on the composition of the intended Ca--At alloy so that the composition of the electrolytic bath is above the above-mentioned value.

Aluminum may be replenished according to the amount of Ca-At alloy taken out.

The conventional electrolytic conditions are applied as they are. A suitable electrolysis temperature is 650 to 7500. Electrolysis temperature is 650
If it is less than 750C, the molten aluminum on the cathode will solidify, which is not preferable, and if it exceeds 750C, the electrolytic cell will deteriorate significantly, which is not preferable.

The molten Ca-At alloy obtained in the present invention is poured into a mold and made into an ingot.

Thereafter, the ingot is remelted into a suitable shape, such as granules or rods. Ca- thus obtained
The method of using At alloy for desulfurization and dephosphorization of molten iron is
- If the At alloy is granular, it is driven into molten iron; if it is rod-shaped, it is inserted into molten iron.

As explained above, the present invention provides efficient Ca-At
The present invention provides a method for producing an alloy, and its advantages are immeasurable when the present invention is implemented industrially. Also, C
Among the a-At alloys, those with a high aluminum content are safe to handle when used for desulfurization and dephosphorization of molten iron, and moreover, when produced by the method of the present invention, they can be handled efficiently as described above. Not only can it be manufactured, but the generated C
The a-A4 alloy can be easily collected from the electrolytic cell. Therefore,
The usefulness of the manufacturing method of the present invention is most apparent when manufacturing Ca--At alloys with high aluminum content.

The present invention will be specifically explained below with reference to Examples and Comparative Examples, but it goes without saying that the present invention is limited to these Examples.

Examples 1-2 and Comparative Examples 1-2 Lithium chloride and anhydrous calcium chloride were blended in a weight ratio as shown in the table below. 100 and 7 were heated and melted at 690C, and an iron cathode was placed at the bottom, and a graphite anode was prepared. was injected into a hanging container.

Metal aluminum 10:7 was added to this melt, and a direct current was passed through it. Thereafter, the composition of the molten metal at the bottom of the electrolytic cell was measured from time to time, and molten calcium chloride was replenished so that the At:Ca weight ratio was maintained at 65:35. When the power consumption in that case was measured, it was as shown in the table below4.

Example 6 The weight ratio of sodium chloride and anhydrous calcium chloride is 60:
10Kq of powder blended to give a concentration of 40% was heated and melted at 690°C, and charged into the same container as in Example 1.

To this melt, 10Kf of granular aluminum was charged and a direct current was passed through it at a density of 0.38/d. Thereafter, the metal accumulated at the bottom was sampled, and when the specific gravity fell to 2.4, the metal at the bottom was extracted. The metal composition at that time is kL
The content was 70% by weight, and the content of Ca was 30% by weight. Moreover, the electric power consumption rate was 20KWH/Kg.

Comparative Example 6 Weight ratio of calcium fluoride to anhydrous calcium chloride is 60
The powder blended so as to have a concentration of 40% was placed in a 'TrL tank and heated to 700°C, but it did not completely melt. When this mixture was heated to 800C, it finally melted, but as a direct current was passed through it, the electrodes were severely worn out and electrolysis could not be continued for a long time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the electrolytic method for producing the Ca--At alloy of the present invention. In the figure, 1 is an electrolytic cell, 2 is an anode, and 3 is a cathode. 4 represents molten aluminum, 5 represents an electrolytic bath, and 6 represents a Ca--At alloy outlet. Patent applicant Tokuyama Soda Co., Ltd. 1 blade 1

Claims (4)

[Claims] (1) In a method for producing a calcium-aluminum alloy by performing molten salt electrolysis of calcium chloride in the presence of molten aluminum, the electrolytic bath contains an alkali metal halide and calcium chloride, and the alkali metal The weight ratio of halide to calcium chloride is 5/2
A method for producing a calcium-aluminum alloy, characterized by using the electrolytic bath as described above. (2) Claim (1) that the weight ratio of the alkali metal halide to calcium chloride is 4/1 or more.
Manufacturing method described. (3) The production method according to claim (1), wherein the alkali metal chloride is lithium chloride. (4) The manufacturing method according to claim (1), wherein the calcium in the calcium-aluminum alloy is 35 weight X or less.