JP6853402B2 - How to handle the secondary battery - Google Patents

Description

The present invention relates to a method for treating a secondary battery, specifically, a method for treating a secondary battery that recovers valuable resources from a secondary battery such as a lithium ion battery.

The lithium ion battery has a feature that the energy density is high and a relatively high voltage can be obtained. For this reason, lithium-ion batteries are widely used as electronic devices such as notebook computers, video cameras, digital cameras, tablet terminals, mobile phones, and in-vehicle batteries.
The lithium ion battery is composed of a housing (case) and a metal case or the like in which a positive electrode, a negative electrode, an electrolytic solution, a separator and the like are enclosed. Aluminum or resin is often used for the case. Iron and aluminum are often used for metal cases. The positive electrode is composed of a positive electrode current collector made of aluminum foil and a positive electrode active material made of a lithium composite oxide such as _{LiCoO 2} , LiNiO ₂ and LiMn ₂ O _{4 bonded to the surface thereof via a binder.} The negative electrode is typically composed of a copper negative electrode current collector and a negative electrode active material made of a carbon material such as graphite adhered to the surface thereof. The electrolytic solution is generally a solution in which a lithium salt is dissolved in a non-aqueous solution such as ethylene carbonate or propylene carbonate. Generally, polyethylene, polypropylene, or the like is used for the separator.

In recent years, as the amount of secondary batteries used such as lithium-ion batteries has increased and the range of use has expanded, the amount of batteries discarded due to product life or defects in the manufacturing process has increased. Under such circumstances, it is desired to easily recover valuable metals such as nickel and cobalt from a large amount of discarded secondary batteries at a relatively low cost.
By the way, the secondary battery is equipped with a substrate used for discharging and charging, voltage control, and the like. However, little attention has been paid to the recovery of gold contained therein, and much research has not been carried out.

Under such circumstances, as described in Patent Document 1, a technique for recovering gold by further sieving, magnetically sorting, eddy current sorting, etc., for a lithium ion battery that has been roasted, crushed, and screened. Has been proposed.

Japanese Unexamined Patent Publication No. 2014-199774

However, according to the technique described in Patent Document 1, it is necessary to go through a number of steps such as crushing, sieving, magnetic force sorting, and eddy current sorting before recovering gold, and the process leading up to recovery is very large. It was complicated.
Further, a method of disassembling the secondary battery by hand to collect the substrate is also conceivable, but the labor cost is high and there is a risk of electric shock, which causes a safety problem.

Therefore, the inventor paid attention to the structure and material of the secondary battery, gasified the electrolytic solution, plastics, and resins by thermal decomposition (250 ° C to 550 ° C), and further crimped the metal. We have found that the substrate, lead frame material, etc. can be separated from the metal case by expanding the metal with heat, and completed the present invention.

An object of the present invention is to provide a method for treating a secondary battery in which a substrate and a lead frame material contained in the secondary battery are separated to recover valuable metals in the heat treatment of the secondary battery.

The invention according to claim 1 is a method for treating a secondary battery, which recovers a noble metal from a secondary battery including a metal part joined by non-metals or a metal part fixed by metal pressure treatment. Is put into a heating furnace, the secondary battery is heated in an environment of 250 to 400 ° C., and the battery gas outflow step of causing the battery gas to flow out from the secondary battery, and after the completion of the battery gas outflow step, this The secondary battery is continuously heated in an environment of 400 ° C. to 550 ° C. in a heating furnace to peel off the metal part containing the noble metal, and then a sieve selection for recovering the noble metal by sieving. The heating furnace has a separate step, and the inside of the heating furnace is divided into a heating space region and a heat treatment space region, and superheated steam is sprayed only on this heat treatment space region. The peeling step is a method for treating a secondary battery, which is performed in the heating space region and is performed in the heat treatment space region.

According to the second aspect of the present invention, in the heating furnace, the secondary battery is charged into the heating space region from the charging port and discharged to the discharge port through the heat treatment space region. A plurality of injection nozzles for spraying the superheated steam are provided in the heat treatment space region, and the injection nozzles are provided perpendicular to the inner wall surface of the furnace wall. The method for processing a secondary battery according to claim 1, wherein the secondary batteries are arranged so as to be long.

The invention according to claim 3 is the method for processing a secondary battery according to claim 1 or 2, wherein the secondary battery is a lithium ion battery.

According to the present invention, the electrolytic solution, plastics, and resins are gasified by placing the secondary battery in an environment of 250 ° C. to 550 ° C. Further, the metal crimping on the outside of the metal case (secondary battery body), the substrate fixed with plastics, the lead frame material, etc. expand due to heat, and the metal case is easily peeled off due to impact or the like. Then, the secondary battery body and metal parts such as the substrate and lead frame material are sieved by a mesh that does not allow the secondary battery body to pass through. Gold, silver, and copper contained in metal parts such as substrates and lead frame materials can be recovered as a sieve only by going through these two steps.

At that time, if the main body of the secondary battery bursts, the positive electrode material and the negative electrode material enclosed inside the battery are mixed, so that the purity of the recovered gold, silver, and copper is lowered, and the recovered gold, silver, and copper are recovered by the subsequent treatment. The recovery rate of nickel, cobalt, etc. decreases. In order to prevent this, it is preferable to let the battery gas flow out from the secondary battery body at 250 ° C. to 400 ° C. and then peel off the metal parts at 400 to 550 ° C.
In this case, it is also possible to perform the outflow of the battery gas from the secondary battery and the peeling of the metal parts with one device. In that case, the processing method of the secondary battery can be simplified, which is advantageous in terms of cost related to the processing of the secondary battery.
At that time, the inside of the heating furnace is divided into a heating space region and a heat treatment space region, and superheated steam of 450 ° C. to 750 ° C. is sent to the secondary battery existing in the heating space region by a plurality of injection nozzles. By spraying only on the heat treatment space region so as not to come into contact with each other, the temperature of the secondary battery existing in the heating space region can be suppressed to about 250 ° C., which is particularly useful.
The main cause of the explosion due to heating of the secondary battery is that the secondary battery is placed at a very high temperature, and the electrolytic solution (volatile organic solvent or alkaline solution) enclosed in the secondary battery is a concern. This is because the battery gas is generated and the volume of the battery gas rapidly increases (expands). The boiling point of this electrolytic solution is about 260 ° C. even if the electrolytic solution is a high boiling point solvent, and is usually 200 ° C. or lower. By suppressing the temperature of the secondary battery to about 250 ° C., it is possible to prevent the temperature of the electrolytic solution from becoming high, and although the electrolytic solution is vaporized to generate battery gas, the volume of the battery gas increases rapidly. There is no such thing. Therefore, in the heat treatment of the secondary battery, it is possible to prevent the housing of the secondary battery from bursting and the aluminum or the like from becoming brittle and becoming finer.
The battery gas refers to a gas generated in the metal case of the secondary battery and released to the outside by heating the secondary battery. In the present invention, the electrolytic solution (volatile organic) sealed in the secondary battery is used. Most of them are vaporized solvents or alkaline solutions (such as potassium hydroxide).

Examples of the secondary battery in the present invention include a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a mobile phone and other secondary batteries that can be used in various electronic devices, in addition to the lithium-ion secondary battery. In particular, it is preferable to target secondary battery scrap that has been discarded due to the life of the battery product, manufacturing defects, or other reasons, from the viewpoint of effective use of resources.

The heating space region refers to a region (section) in which an inlet and a blower are provided in the inside of the heating furnace composed of the furnace wall. In the heating space region, the secondary battery is heated so that the temperature of the secondary battery reaches about 260 ° C., and a heating outflow treatment is performed in which the battery gas flows out from the inside of the housing of the secondary battery.
Superheated steam (heat source, heat medium) does not come into direct contact with the secondary battery existing in the heating space region. Since the secondary battery is heated by the residual heat of the heat treatment in the heat treatment space region, the heating temperature of the secondary battery is about 250 ° C.

The heat treatment space region refers to a region (section) in which a discharge port and a plurality of injection nozzles are provided in the inside of a heating furnace composed of a furnace wall. In the heat treatment space region, the secondary battery after the outflow of the battery gas is heat-treated with superheated steam at 450 ° C. to 750 ° C. The heat treatment is performed for the purpose of removing and vaporizing the electrolytic solution inside the secondary battery and peeling off the metal parts fixed by joining or crimping with non-metals.
The cross-sectional shape, diameter, and length of the injection nozzle are arbitrary and may be the same cross-sectional shape, the same diameter, and the same length, or may be different cross-sectional shapes, different diameters, and different lengths. .. However, from the viewpoint of facilitating the control of the steam flow and improving the efficiency of the heat treatment of the secondary battery, the injection nozzle is provided perpendicular to the inner wall surface of the furnace wall, and the closer it is to the discharge port, the more the injection nozzle is injected. It is preferable to arrange the nozzles so that the length of the nozzles is long.

According to the present invention, by placing the secondary battery in an environment of 250 ° C. to 550 ° C., the electrolytic solution, plastics, and resins are gasified, and the metal case is fixed to the outside with metal crimping and plastics. The substrate, lead frame material, etc. are expanded by heat. Then, the metal case and the substrate / lead frame material are sieved by a mesh that does not allow the metal case to pass through. Gold, silver, and copper can be recovered simply by going through these two steps.

In particular, according to the invention of claim 2, the injection nozzle is provided perpendicular to the inner wall surface of the furnace wall, and is arranged so that the closer to the discharge port, the longer the length of the injection nozzle. As a result, it is possible to easily control the flow of steam and improve the efficiency of the heat treatment of the secondary battery.

In the invention according to claim 3, the secondary battery is limited to the lithium ion battery, which is a lithium ion battery containing an electrolytic solution (volatile organic solvent), which is technically particularly difficult to handle. However, it can be processed without any problem.

It is a flowchart which shows the processing flow of the secondary battery which concerns on embodiment of this invention. It is sectional drawing which shows the secondary battery heat treatment apparatus in the processing method of the secondary battery which concerns on the modification of this invention.

Hereinafter, examples of the present invention will be described in detail.

(Test of behavior confirmation of electrolyte in temperature range)
A 35 mm × 35 mm × 0.5 mm lithium ion battery for a mobile phone was heat-treated in an argon atmosphere in a small electric furnace having a furnace temperature of 200 ° C., 250 ° C., 300 ° C., 350 ° C., and 400 ° C. The heat treatment time was 10 minutes, 20 minutes, and 30 minutes.
The composition of the lithium ion battery used was 16.90 g of the lithium ion battery body, and the amount of the enclosed electrolytic solution was 2.09 g.
The weight of the lithium-ion battery after the heat treatment was measured, and the volatilization rate of the electrolytic solution was determined. The results are shown in Table 1.

According to the above test results, at 200 ° C., the amount of volatilization of the electrolytic solution is as low as 1.0% even after the heat treatment time has passed for 30 minutes, and it can be seen that the electrolytic solution is hardly volatilized. At 250 ° C., the heat treatment time was 81.9% after 20 minutes and 96.2% after 30 minutes, and the volatilization of the electrolytic solution progressed with the passage of time. Was a high value of 99.5%.
In the heat treatment at 400 ° C., the opening sound of the gasket (gas vent) of the lithium ion battery was confirmed about 3 minutes after the start of the test, and if the heat treatment was performed at a temperature higher than this, the lithium ion battery might explode. No tests above ° C were performed.

(Peeling metal parts of lithium-ion batteries for mobile phones)
A 35 mm × 35 mm × 0.5 mm lithium ion battery for a mobile phone was heat-treated in an argon atmosphere in a small electric furnace having a furnace temperature of 400 ° C., 450 ° C., and 500 ° C. The heat treatment time was 30 minutes, 45 minutes, and 60 minutes.
The composition of the lithium-ion battery used was 16.90 g (89.0 wt%) of the lithium-ion battery body, 1.22 g (6.4 wt%) of plastic, 0.53 g (2.8 wt%) of the target substrate, and 0.34 g of stainless steel. (1.8 wt%), and the total weight was 18.99 g.
The weight of the lithium-ion battery after the heat treatment was measured, and the volatility was determined. The results are shown in Table 2.

The lithium-ion battery after heat treatment at 450 ° C. for 45 minutes or more collapses due to a light impact when it is taken out from the furnace, and the IC chip, copper, etc. mounted on the substrate are a glass fiber base substrate (heat treatment). The resin constituting the substrate was removed by the above method.)

(Recovery of precious metals from lithium-ion batteries for mobile phones)
As shown in FIG. 1, five lithium-ion batteries (94.14 g) described above were used as raw materials, which were subjected to thermal decomposition and then sieved.
(Pyrolysis treatment)
Pyrolysis treatment was performed in an argon atmosphere in a small electric furnace. Regarding the thermal decomposition temperature and time, first, heating was performed at 400 ° C. for 20 minutes, and then heat treatment was performed at 450 ° C. for 40 minutes.
(Sieving process)
As for sieving, primary sieving was performed with a sieving mesh of 10 mm, and then secondary sieving was performed with a sieving mesh of 1 mm. In this example, sieving was performed twice, but the number of times of sieving may be one or more, and the number of times is not limited at all.

When the sieving step was performed, the lithium ion battery body (above the sieving) and other substances (below the sieving) were separated by the primary sieving. Then, by the secondary sieving, the lead frame (terminal) and the substrate (on the sieving) and other substances (residual carbon) (under the sieving) could be separated.
When gold, silver, and copper were analyzed for the lead frame (terminal) and substrate existing on the sieve in the secondary sieving, gold was 2930 ppm (recovery rate 99.7%) and silver was 2020 ppm (recovery rate 89.4). %) Was included. The percentage of copper, which is a material for wiring formed on the lead frame and the substrate, was 17.6%.
Then, when gold, silver, and copper were analyzed for the residual carbon existing under the sieve in the secondary sieving, gold contained 20 ppm (recovery rate 0.3%) and silver contained 517 ppm (recovery rate 10.6%). It was.
From this, by recovering the lead frame (terminal) and the substrate existing on the sieve in the secondary sieving, the precious metals gold and silver could be recovered in high yield.

(Modified example of recovery of precious metals from lithium-ion batteries for mobile phones)
In the first embodiment, the thermal decomposition treatment was performed in a small electric furnace, but as a modification, a secondary battery heat treatment apparatus as shown in FIG. 2 can be used.

The secondary battery heat treatment device 10 according to the modified example of the present invention is arranged inside the heating device main body 11 having a rotating tubular furnace wall and the heating device main body 11, and is arranged according to the rotation of the furnace wall. A superheated steam pipe 12 having a length of 3/4 of the length of the furnace wall that does not rotate, a plurality of injection nozzles 13 protruding from the superheated steam pipe at equal intervals, and suction fixed to the heating device main body 11. It is provided with a duct 14. Further, the secondary battery heating device 10 includes a raw material supply unit 16 provided with a raw material supply feeder 15 for charging the secondary battery into the heating device main body 11, and a discharge unit 17 for discharging the secondary battery after thermal decomposition. I have.

The heating device main body 11 is formed of castable concrete in a cylindrical shape, and includes a furnace wall provided with side walls made of castable concrete at both ends. That is, the heating device main body 11 has a circular closed internal space when viewed in a side cross section. An iron surface covering material is provided on the outer wall surface of the furnace wall.
The raw material supply unit 16 is fixed to one side of the two side walls of the heating device main body 11, and the discharge unit 17 is fixed to the other side.
The raw material supply unit 16 is formed with a supply port for supplying the secondary battery to the inside of the heating device main body 11, and is attached with a supply lid for opening and closing the supply port mechanically or electromagnetically. This supply lid opens and closes the supply port physically (mechanically) or electromagnetically. The raw material supply unit 16 is provided with a raw material supply feeder 15 that supplies raw materials for supplying a secondary battery to the inside of the heating device main body 11 via a supply port. The raw material supply feeder 15 has a vibrator, and when the raw material supply feeder 15 vibrates, the secondary battery moves to the inside of the heating device main body 11 while vibrating.
The discharge unit 17 is provided with a discharge port for discharging the heat-treated secondary battery to the outside of the heating device main body 11, and a discharge lid for opening and closing the discharge port mechanically or electromagnetically is attached. ing.

The superheated steam pipe 12 is a fixed (non-rotating) pipe that supplies superheated steam at 450 ° C. to 750 ° C. generated in a steam generator provided outside the heating device main body 11 to the inside of the heating device main body 11. .. The superheated steam pipe 12 is provided so as to project from the side wall of the heating device main body 11 near the discharge portion 17 toward the side wall close to the raw material supply portion 16. The protruding length of the superheated steam pipe 12 is set to 3/4 of the length in the longitudinal direction of the heating device main body 11 (that is, the distance between the two side walls). The end of the superheated steam pipe 12 is plugged. A plurality of injection nozzles fixed at equal intervals are provided on the pipe wall of the superheated steam pipe 12.
The injection nozzle 13 is provided so as to be perpendicular to the superheated steam pipe and also perpendicular to the inner wall surface of the furnace wall of the heating device main body 11. The plurality of injection nozzles 13 have the same cross-sectional shape and the same diameter, but all have different lengths. The plurality of injection nozzles are arranged so that the closer to the discharge port, the longer the length of the injection nozzles.

With the above configuration, the inside of the heating device main body 11 is divided into a heat treatment space region in which steam is injected from the injection nozzle 13 and a heating space region which is another region.
The suction duct 14 is provided in the heating space region of the heating device main body 11.
The suction duct 14 sucks the heat-treated gas, steam, or the like released by the heat-treated secondary battery as a pyrolysis gas in the pyrolysis region. The suction output of the suction duct 14 is adjusted so that the superheated steam can be sucked so as not to come into contact with the secondary battery existing in the heating space region. That is, the superheated steam passing through the heating space region is sucked by the suction duct 14 substantially linearly.

When the secondary battery is heat-treated using this heat treatment device, the battery gas is discharged from the secondary battery at 250 ° C to 400 ° C, and then the metal parts are peeled off at 400 ° C to 450 ° C. Deterioration of the purity of gold, silver, and copper recovered due to the mixing of the positive electrode material and negative electrode material enclosed inside the battery due to the rupture of the next battery, and the recovery rate of nickel, cobalt, etc. recovered by the subsequent treatment. Can be prevented from decreasing.

Claims (3)

A method for processing a secondary battery that recovers precious metals from a secondary battery that includes metal parts joined by non-metals or metal parts fixed by metal crimping.
A battery gas outflow process in which a secondary battery is put into a heating furnace, the secondary battery is heated in an environment of 250 to 400 ° C., and the battery gas is discharged from the secondary battery.
After the completion of the battery gas outflow step, the secondary battery is continuously heated in the heating furnace in an environment of 400 ° C. to 550 ° C. to peel off the metal parts containing the precious metal, and a peeling step.
Then, it has a sieving sorting step of recovering the noble metal by sieving.
The inside of the heating furnace is divided into a heating space region and a heat treatment space region, and superheated steam is sprayed only on this heat treatment space region.
The battery gas outflow step is performed in the heating space region, and the battery gas outflow step is performed.
The peeling step is a method for processing a secondary battery performed in the heat treatment space region. In the heating furnace, the secondary battery is charged into the heating space region from the inlet, and discharged to the discharge port through the heat treatment space region.
A plurality of injection nozzles for spraying the superheated steam are provided in the heat treatment space region of the heating furnace.
The method for processing a secondary battery according to claim 1, wherein the injection nozzle is provided perpendicular to the inner wall surface of the furnace wall, and is arranged so that the length of the injection nozzle becomes longer as it is closer to the discharge port. The method for processing a secondary battery according to claim 1 or 2, wherein the secondary battery is a lithium ion battery.

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