JP2740621B2 - How to treat used sodium-sulfur batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a used sodium-sulfur battery for recovering useful substances from waste of a sodium-sulfur battery being developed as a power storage battery or a power source for an electric vehicle. It relates to a processing method.

[0002]

2. Description of the Related Art A sodium-sulfur battery has a solid electrolyte tube made of β-alumina and both sides filled with sodium as a cathode active material and sulfur as an anode active material. It is a secondary battery with a protected structure. This sodium-sulfur battery is being developed as the most suitable battery for power storage, but it gradually deteriorates during repeated charging and discharging, so after the end of its useful life of 10 years, It is considered that a large amount of sulfur batteries are generated.

Since such a used sodium-sulfur battery processing technique has not been completed yet, it may be possible to keep it as it is. However, since the sodium and sulfur batteries contain sodium and sulfur, which are specified as dangerous goods by the Fire Service Law, the amount that can be stored in one place is limited. It is difficult to keep.

The only prior art relating to the treatment of a used sodium-sulfur battery is disclosed in Japanese Patent Laid-Open No. 3-88281. According to this publication, after recovering sodium from a used sodium-sulfur battery, the outer container is separated from the anode, the outer container is washed with an alcohol bath and reused, and the anode is incinerated to recover sulfuric acid. It is stated that. However, since the outer container of a sodium-sulfur battery that has been used for a long period of time may be damaged, it is assumed that it is not acceptable in Japan to reuse it only by washing it with an alcohol bath. In the process of recovering sulfuric acid, the equipment may be acid-corroded.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and does not corrode equipment from a used sodium-sulfur battery without removing aluminum, a metal film on its surface, sodium, sulfur, and polysulfide. Soda (Na ₂ S _x )
It has been completed in order to provide a method for treating a used sodium-sulfur battery which can separate and collect the same.

[0006]

According to a first aspect of the present invention, a cap of a used sodium-sulfur battery is cut, and sodium is recovered in paraffin. The outer container is heated to 700 to 1200 ° C. on a separation medium in a heating furnace to drop aluminum, and the aluminum and the metal film remaining on the separation medium are separated and recovered.

In a second aspect of the present invention, the cap of the used sodium-sulfur battery is cut off, the sodium is recovered in paraffin, the outer container is peeled off, and the remainder is heated in an inert atmosphere to evaporate the sulfur. It is characterized in that the evaporated sulfur is cooled and solidified and recovered as solid sulfur.

In a third aspect of the present invention, the cap of the used sodium-sulfur battery is cut off, the sodium is recovered in paraffin, the outer container is peeled off, and the remaining Na ₂ S _x x is removed in an inert atmosphere. While heating to the temperature corresponding to the value to evaporate sulfur, the evaporated sulfur is cooled and solidified to recover solid sulfur, and the part after sulfur separation is immersed in alcohol or water to extract and recover Na ₂ S _x It is characterized by doing. The first invention and the second invention can be performed in a series of steps, and the first invention and the third invention can be performed in a series of steps.

[0009]

According to the first aspect of the invention, sodium, aluminum, and an expensive metal film on the surface thereof can be separately recovered from the used sodium-sulfur battery. According to the second invention, sodium and sulfur can be separately recovered from the used sodium-sulfur battery. According to the third invention, sodium and sodium polysulfide, which is a valuable substance, can be separated and recovered from the used sodium-sulfur battery.
In any of the inventions, there is no possibility of acid corrosion of the equipment. Each of the inventions will be described in detail below in order.
Fig. 1 shows the entire processing flow of a used sodium-sulfur battery integrating the respective inventions.

[0010]

【Example】

(First Invention) FIG. 2 is a view showing a sectional structure of a used sodium-sulfur battery, wherein 1 is an outer peripheral container made of aluminum, 2 is a solid electrolyte tube made of β-alumina housed therein, 3 is sulfur as an anode active material, 4 is sodium as a cathode active material, 5 is a cap, and 6 is a current collector. Stellite (Co-Cr-W-
C-based alloy).

First, the cap 5 of the used sodium-sulfur battery is mechanically cut, and if necessary, a hole is drilled from above to open the upper part of the electrode, thereby exposing the cathode part as shown in FIG. . Next, as shown in FIG. 4, a tank 7 containing paraffin 8 heated to a temperature not lower than the melting point of sodium is used.
It is immersed inside with the opening facing downward. Then, sodium having a higher specific gravity than paraffin 8 flows down to the bottom of the tank 7 and can be collected. Although sodium reacts violently upon contact with water, no reaction occurs because paraffin 8 does not contain water at all, and sodium in the cathode portion is easily recovered.

After recovering the sodium in this way,
The outer peripheral container 1 of the used sodium-sulfur battery is mechanically peeled off from the solid electrolyte tube 2 made of β-alumina, and the outer peripheral container 1 is divided into, for example, two equal parts in the vertical direction to have a semicircular cross section. This is placed on a tape-like or net-like separation medium 10 in a heating furnace 9 as shown in FIG. 5 and heated to 700 to 1200 ° C. Then, aluminum having a melting point of about 660 ° C. is melted and dropped from the separation medium 10 into the lower container 11, and only a metal film such as stellite having a melting point higher than 1200 ° C. remains on the separation medium 10. After the aluminum and the metal film are completely separated in this way, the metal film may be taken out from the separation medium 10. The purity of the aluminum recovered in the container 11 is 99% or more, which is highly useful, and a metal film such as stellite can be reused as a raw material for producing high-speed steel.

(Second Invention) On the other hand, the remaining portion of the outer container 1, which has been peeled off, exposes the sulfur 3 of the anode portion as shown in FIG. Then, as shown in FIG. 7, this is placed in a heating furnace 12 such as an electric furnace, and heated to 200 to 1000 ° C. in an inert gas atmosphere. Then, the sulfur 3 in the anode portion evaporates without being oxidized.
At 15, it is led to a cooling and solidifying device 16, and is cooled and solidified. As a result, sulfur having a purity of 99.9% or more is obtained, and this sulfur can be reused as an anode active material of a sodium-sulfur battery. The exhaust gas from the heating furnace 12 is a scrubber
After passing through 17, it can be released into the atmosphere. According to this method, sulfur is evaporated, solidified by cooling, and recovered as solid sulfur. Therefore, unlike the conventional method, sulfuric acid or the like which may corrode equipment is not generated.

(Third invention) The second invention is directed to recovering sulfur, but the third invention is directed to Na ₂ S
It is for the purpose of recovering _x (sodium polysulfide). Also in the third invention, the sulfur (3) of the remaining portion (anode portion) from which the outer peripheral container 1 has been peeled off is exposed and put into a heating furnace 12 such as an electric furnace as shown in FIG. ~ 1000
C. to evaporate the sulfur in the anode part. But the third
According to the invention, sulfur is evaporated by heating to a temperature corresponding to the x value of Na ₂ S _x to be recovered. This is because it was confirmed that there was a relationship as shown in FIG. 8 between the heating temperature and the x value of Na ₂ S _x recovered in the subsequent step. Therefore, if you want to recover the Na ₂ S ₆ in a subsequent step for example may be heated at about 350 ° C., when it is desired to recover the Na ₂ S ₃ in a subsequent step may be heated at about 1000 ° C..

In this way, the sulfur 3 is evaporated, the steam of sulfur is cooled and solidified to recover solid sulfur in the same manner as in the second invention, and the anode portion after sulfur separation is crushed as shown in FIG. Or immersed in water 18 and contained Na ₂ S _x in the anode part
Then, the solid is removed by filtration to recover Na ₂ S _x , or the anode part after sulfur separation is directly immersed in alcohol or water 18 as shown in the example of FIG. 10 to be included in the anode part.
Extract and recover Na ₂ S _x . The amount of alcohol or water at the time of extraction may be about 100 cc per 1 g of the anode part, and the anode part is immersed at room temperature for about 30 minutes. FIG. 10 shows that the anode part after sulfur separation is placed on a conveyor 19 and alcohol or water 18
The speed of the conveyor 19 is adjusted so that the anode part can be immersed for a required time.

Na ₂ S _x has various uses such as dyes and chemicals according to its x value. According to the third invention, the x value of Na ₂ S _x can be freely controlled by the temperature in the preceding step. Na ₂ S _x having the desired x value can be obtained. Since the filtered solid contains the carbon mat constituting the anode, it can be used again as a carbon mat after drying.

[0017]

As described above in detail, according to the first aspect, sodium, aluminum, and an expensive metal film on the surface thereof are separated and recovered from the used sodium-sulfur battery. be able to. According to the second invention, sodium and sulfur can be separated and recovered from the used sodium-sulfur battery. According to the third invention, sodium and valuable can be recovered from the used sodium-sulfur battery. Sodium polysulfide, which is a substance, can be separated and recovered. In any of the inventions, sulfuric acid is not generated in the treatment process unlike the conventional method, and therefore, there is no possibility that the equipment is subjected to acid corrosion. Therefore, the present invention has an extremely large contribution to industrial development as a method for treating a used sodium-sulfur battery that has solved the conventional problems.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the entire processing flow of a used sodium-sulfur battery.

FIG. 2 is a sectional view showing a used sodium-sulfur battery.

FIG. 3 is a sectional view showing a state in which a cap of a used sodium-sulfur battery is cut and drilled.

FIG. 4 is a sectional view showing a step of recovering sodium from a used sodium-sulfur battery.

FIG. 5 is a sectional view showing a step of separating and recovering aluminum and a metal film from a used sodium-sulfur battery.

FIG. 6 is a sectional view showing a state in which an outer peripheral container of a used sodium-sulfur battery is peeled off.

FIG. 7 is a sectional view showing a sulfur recovery step.

FIG. 8 is a graph showing a relationship between a heating temperature in a sulfur recovery step and an x value of Na ₂ S _x recovered in a subsequent step.

FIG. 9 is a cross-sectional view showing an example of a step of extracting Na ₂ S _x from a crushed product of the anode part after sulfur separation.

FIG. 10 is a cross-sectional view illustrating an example of a step of extracting Na ₂ S _x from an anode portion after sulfur separation.

[Explanation of symbols]

Reference Signs List 1 outer container, 2 solid electrolyte tube, 3 anode active material sulfur, 4 cathode active material sodium, 5 cap, 6 current collector rod, 7 tank, 8 paraffin, 9 heating furnace, 10 separation medium, 11 container, 12 Heating furnace, 14 heaters, 15 pipes, 16 cooling and solidifying equipment, 17 scrubbers,
18 alcohol or water, 19 conveyor

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Kurashima 17-20, Hanaomote-cho, Atsuta-ku, Nagoya-shi, Aichi Hanaomote-danchi 314 (56) References JP-A-3-88281 (JP, A) Hei 3-203173 (JP, A) U.S. Pat. No. 4,801,443 (US, A) PAUL PEMSLER ET AL. , "RECYCLE OF B ATTERIAL MATERIALS", INTERSOCITY ENERGY CONVERSION ENGINE EERING CONFERENCE, U.S.A. S. A. , 1981, VOL. 16, NO. 1, P. 695-698

Claims (5)

(57) [Claims] 1. A cap of a used sodium-sulfur battery is cut, and after collecting sodium in paraffin, an outer container is peeled off, and the outer container is heated to 700 to 1200 ° C. on a separation medium in a heating furnace to remove aluminum. , And the aluminum and the metal film remaining on the separation medium are separated and collected. 2. The cap of a used sodium-sulfur battery is cut off, the sodium is recovered in paraffin, the outer container is peeled off, and the remainder is heated in an inert atmosphere to evaporate the sulfur, and the evaporated sulfur is cooled. A method for treating a used sodium-sulfur battery, comprising solidifying and recovering as solid sulfur. 3. The cap of the used sodium-sulfur battery is cut off, the sodium is recovered in paraffin, the outer container is peeled off, and the remaining Na is recovered in an inert atmosphere.
_{2 While} heating to the temperature corresponding to the x value of S _x to evaporate the sulfur, the evaporated sulfur is cooled and solidified to recover solid sulfur, and the part after sulfur separation is immersed in alcohol or water.
A method for treating a used sodium-sulfur battery, wherein Na ₂ S _x is extracted and recovered. 4. The cap of the used sodium-sulfur battery is cut, and after collecting sodium in paraffin, the outer container is peeled off, and the outer container is heated to 700 to 1200 ° C. on a separation medium in a heating furnace to remove aluminum. And the aluminum and the metal film remaining on the separation medium are separated and recovered, while the remainder is heated in an inert atmosphere to evaporate the sulfur, and the evaporated sulfur is cooled and solidified to be recovered as solid sulfur A method for treating a used sodium-sulfur battery. 5. The cap of a used sodium-sulfur battery is cut off, and after recovering sodium in paraffin, the outer container is peeled off, and the outer container is heated to 700 to 1200 ° C. on a separation medium in a heating furnace to obtain aluminum. And the aluminum and the metal film remaining on the separation medium are separated and recovered, while the remainder is a target Na in an inert atmosphere.
_{2 While} heating to the temperature corresponding to the x value of S _x to evaporate the sulfur, the evaporated sulfur is cooled and solidified to recover solid sulfur, and the part after sulfur separation is immersed in alcohol or water.
A method for treating a used sodium-sulfur battery, wherein Na ₂ S _x is extracted and recovered.