A method and system for recovering valuable metals from lithium cobalt oxide batteries

Abstract

The present invention provides a method and system for recovering valuable metals from lithium cobalt oxide batteries. The method comprises the following steps: mixing the positive electrode material and the negative electrode material of the lithium cobalt oxide battery to obtain a mixture; placing the mixture under a pressure of 10Pa to 100Pa and heating it to 1300K to 1600K, and after the reaction is completed, respectively recovering the solid phase containing elemental cobalt and the gas phase containing lithium oxide to complete the recovery of valuable metals. The recovery method of the present invention does not require the addition of other reaction substances, and is carried out in a closed vacuum environment, which is energy-saving and environmentally friendly; the method and system of the present invention can achieve a recovery rate of more than 98% for metallic cobalt and lithium oxide, and the purity can reach more than 99%.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium cobalt oxide batteries, and more specifically, to a method and system for recovering valuable metals from lithium cobalt oxide batteries. Background Art

[0002] As the earliest commercially available high-energy density battery, lithium cobalt oxide batteries are widely used in the production of portable electronic devices and energy storage devices. With the development of the information industry, the large-scale production of electronic and electrical products has led to the large-scale retirement of batteries, which has caused increasingly serious harm to the environment, such as soil and water pollution. Therefore, how to effectively recycle the valuable metals in lithium cobalt oxide batteries has become an urgent problem to be solved. Summary of the invention

[0003] In view of the deficiencies in the prior art, one of the purposes of the present invention is to solve one or more problems in the prior art. For example, one of the purposes of the present invention is to provide an efficient and environmentally friendly method for recovering valuable metals from lithium cobalt oxide batteries.

[0004] One aspect of the present invention provides a method for recovering valuable metals from a lithium cobalt oxide battery, which may include the following steps: mixing a positive electrode material and a negative electrode material of the lithium cobalt oxide battery to obtain a mixture; placing the mixture under a system pressure of 10Pa to 100Pa, heating it to 1300K to 1600K, and after the reaction is completed, respectively recovering a solid phase containing elemental cobalt and a gas phase containing lithium oxide to complete the recovery of valuable metals.

[0005] Furthermore, the reaction time is 100 min to 150 min.

[0006] Furthermore, it also includes adding anhydrous ethanol into the mixture, wherein the amount of anhydrous ethanol added is 1 / 10 to 1 / 3 of the mass of the mixture.

[0007] Furthermore, it also includes heating the mixture to 1053K~1093K at a heating rate of 8℃ / min~12℃ / min after obtaining the mixture, keeping the temperature for 25min~35min, and then heating the mixture to 1300K~1600K at a heating rate of 8℃ / min~12℃ / min.

[0008] Furthermore, the mass ratio of the positive electrode material to the negative electrode material is 32:1 to 16:1.

[0009] Another aspect of the present invention provides a system for recovering valuable metals from lithium cobalt oxide batteries, comprising an outer body and a reactor, wherein the outer body comprises a collecting chamber, a reaction chamber arranged at the bottom of the collecting chamber, and a flow channel between the collecting chamber and the reaction chamber; the reactor is placed in the reaction chamber, and after the mixture of positive electrode material and negative electrode material of the lithium cobalt oxide battery reacts in the reactor, the gas phase containing lithium oxide enters the collecting chamber through the flow channel for recovery.

[0010] Furthermore, the radial diameter of the collection chamber is larger than the radial diameter of the reaction chamber, and the radial diameter of the reaction chamber is larger than the radial diameter of the circulation channel.

[0011] The recycling principle of the present invention includes: mixing the positive electrode material and the negative electrode material of the waste lithium cobalt oxide battery, and heating to 1300K~1600K under 10Pa~100Pa conditions to make the lithium cobalt oxide and the negative electrode graphite react as follows:

[0012] LiCoO2+C=1 / 2Li2O+Co+3 / 4CO (1)

[0013] LiCoO2+C=1 / 2Li2O+Co+3 / 8CO2 (2)

[0014] By calculating the saturated vapor pressure of lithium oxide and cobalt, it can be known that under the above pressure and temperature conditions, lithium oxide is in the gas phase, while cobalt has not yet melted, and almost no cobalt will enter the gas phase, so the separation of cobalt and lithium oxide can be achieved.

[0015] For the possible intermediate product Li2CO3, the following reaction will occur under the pressure of 10Pa to 100Pa in the recovery method of the present invention:

[0016] Li2CO3=Li2O+CO2 (3)

[0017] For reaction (3), the reaction temperature at 100 Pa is 1200 K, and the reaction temperature at 10 Pa is 1000 K. Therefore, at the reaction temperature of the invention (1300 K to 1600 K), Li2CO3 does not exist, but is directly converted into lithium oxide.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0019] (1) The recovery method of the present invention does not require the addition of other reaction substances and is carried out in a closed vacuum environment, which is energy-saving and environmentally friendly;

[0020] (2) The method and system of the present invention can achieve a recovery rate of metallic cobalt and lithium oxide of more than 98%, and a purity of more than 99%.

[0021] (3) The recovery method of the present invention has a short process flow and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects and features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram of an exemplary system for recovering valuable metals from lithium cobalt oxide batteries;

[0024] Figure 2 is the solid phase XRD pattern of Example 1;

[0025] Figure 3 This is the XRD diagram of the gas phase of Example 1. DETAILED DESCRIPTION

[0026] Hereinafter, a method and system for recovering valuable metals from a lithium cobalt oxide battery according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0027] One aspect of the present invention provides a method for recovering valuable metals from a lithium cobalt oxide battery. In an exemplary embodiment of the method for recovering valuable metals from a lithium cobalt oxide battery of the present invention, the following steps may be included:

[0028] Step 1: Mix the positive electrode material and the negative electrode material of the lithium cobalt oxide battery to obtain a mixture. The positive electrode material of the lithium cobalt oxide battery mainly comprises lithium cobalt oxide, and the negative electrode material mainly comprises graphite.

[0029] Step 2, placing the mixture under a system pressure of 10Pa to 100Pa, heating it to 1300K to 1600K, and recovering the solid phase containing elemental cobalt and the gas phase containing lithium oxide after the reaction is completed, and completing the recovery of valuable metals. Under the above system pressure and temperature, lithium oxide will become a gas while cobalt still exists in the form of a solid, and the lithium and cobalt elements will present two different states, thereby realizing the separation and recovery of cobalt and lithium. Here, it should be noted that different system pressures correspond to different reaction temperatures, and it is known in the art that the reaction temperature of the present invention will decrease with the decrease of system pressure. For example, at 10Pa, the corresponding reaction temperature can be 1300K, and at 100Pa, the corresponding reaction temperature can be 1600K. Of course, higher temperatures can also be used under low pressure, for example, at a pressure of 10Pa, the reaction temperature can be 1600K. For another example, at 20Pa to 50Pa, the reaction temperature can be 1350K to 1450K. Since the reaction between lithium cobalt oxide and graphite in the present invention is an endothermic reaction, if the temperature is lower than 1300K, the reaction speed will be too slow or even no reaction will occur; if the temperature is higher than 1600K, lithium may be generated under low pressure. The generated lithium will cause the lithium to be rapidly oxidized when air quickly enters the reaction environment, resulting in a violent reaction and easy danger.

[0030] In some embodiments, the reaction time may be 100 min to 150 min. Under the above reaction time, the recovery of cobalt and lithium can be maximized while avoiding ineffective reaction time and increased energy consumption. For example, the reaction time may be 110 min, 115 min, 120 min, 130 min, 140 min, 145 min or a combination of the above values.

[0031] In some embodiments, the lithium oxide in the gas phase needs to be condensed at a suitable temperature before it can be recovered. Under a system pressure of 10Pa to 100Pa, the temperature for lithium oxide recovery can be set at 1132K to 1217K. At this recovery condensation temperature, lithium oxide recovery can be achieved and the recovery of lithium oxide can be maximized. Too low or too high a temperature will result in a low recovery rate of lithium oxide or even no recovery.

[0032] In some embodiments, the mixture can be placed under a system pressure of 25Pa to 92Pa and heated to 1200K to 1300K until the reaction is complete. For example, the mixture can be heated to 1250K to 1350K under a system pressure of 40Pa to 75Pa, and for another example, heated to 1280K to 1320K under a system pressure of 55Pa to 75Pa.

[0033] In some embodiments, in order to prevent the mixture of lithium cobalt oxide and graphite from being blown out by the mixed gas of CO and CO2 generated during the reaction, anhydrous ethanol of 1 / 10 to 1 / 3 of the mass of the mixture is added as a binder after the two are mixed. The amount of anhydrous ethanol cannot be less than 1 / 10 of the total mass, nor can it exceed 1 / 3 of the total mass. Adding too little anhydrous ethanol will result in failure to achieve the bonding effect, causing the mixed material to be blown out during the reaction; adding too much anhydrous ethanol will cause the material to be blown out by the volatilized ethanol vapor during the heating process.

[0034] In some embodiments, through observation of the air pressure during the experiment, it is found that when the pressure is reduced to below 100Pa, the air pressure begins to rise sharply at 700°C, and the temperature continues to rise at a heating rate of 10°C / min. When the temperature rises to 900°C, the air pressure drops rapidly and remains basically stable (50Pa-80Pa). The air pressure continues to drop during the insulation stage and is basically stable after 1.5 hours of insulation (10Pa-20Pa). Therefore, the present invention sets 1053K~1093K and insulation for 25min~35min to stabilize the air pressure in the furnace basically below 100Pa. For example, after obtaining the mixture, the temperature can be increased to 1053K-1093K at a heating rate of 8°C / min-12°C / min, kept warm for 25min-35min, and then increased to 1300K-1600K at a heating rate of 8°C / min-12°C / min; for another example, after obtaining the mixture, the temperature can be increased to 1073K at a heating rate of 10°C / min, kept warm for 30min, and then increased to 1300K-1600K at a heating rate of 10°C / min.

[0035] In some embodiments, the mass ratio of the positive electrode material to the negative electrode material can be 32:1 to 16:1. Within this ratio range, it can be ensured that the valuable metals of the positive electrode will be completely recovered. For example, the mass ratio of the positive electrode material to the negative electrode material can be (18-30):1, (22-27):1, (24-26):1, or a combination of the above ranges.

[0036] Another aspect of the present invention provides a system for recovering valuable metals from a lithium cobalt oxide battery. In an exemplary embodiment of the system for recovering valuable metals from a lithium cobalt oxide battery of the present invention, Figure 1 As shown, it may include an outer body 1 and a reactor 2. The outer body 1 includes a collection chamber 1a, a reaction chamber 1b disposed at the lower part of the collection chamber, and a flow channel 1c between the collection chamber 1a and the reaction chamber 1b. The reactor 2 is placed in the reaction chamber 1b. After the positive electrode material and the negative electrode material mixture of the cobalt oxide lithium battery react in the reactor 2, the gas phase containing lithium oxide enters the collection chamber 1a through the flow channel 1c for recovery.

[0037] In some embodiments, the radial diameter of the collection chamber 1a is larger than the radial diameter of the reaction chamber 1b, and the radial diameter of the reaction chamber 1b is larger than the radial diameter of the flow channel 1c. The above arrangement facilitates the recovery of the lithium oxide-containing gas phase material.

[0038] In some embodiments, the reactor 2 can be an iron crucible. Because the cobalt generated by the reaction is in contact with the iron crucible, the iron and cobalt will adhere to each other and there will be a magnetic transition. In addition, in order to make the iron crucible reusable, iron foil can be placed at the bottom of the iron crucible and the inner side wall connected to the bottom. In some embodiments, the outer body 1 can be made of carbon material. Since iron and carbon can form an alloy at 1185K, iron foil can be placed at the side contact between the bottom of the iron crucible and the graphite reactor to avoid direct contact between the iron crucible and the graphite crucible. The damage to the graphite reactor when the iron crucible is taken out after the reaction is caused, and the iron foil has an excellent thermal conductivity and has little effect on the temperature measurement of the bottom thermocouple.

[0039] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific examples, but the content of the present invention is not limited to the following examples.

[0040] Example 1

[0041] A method for recovering valuable metals from a lithium cobalt oxide battery comprises the following steps:

[0042] Step 1: Mix the positive electrode material and the negative electrode material of the lithium cobalt oxide battery to obtain a mixture, wherein the mass ratio of the positive electrode material to the negative electrode material is 25:1.

[0043] Step 2, placing the mixture under a system pressure of 11Pa, heating to 1300K and keeping the temperature for 2 hours, after the reaction is completed, recovering the solid phase containing elemental cobalt and recovering the gas phase containing lithium oxide at 1182K, completing the recovery of valuable metals, wherein the solid phase is subjected to XRD inspection, such as Figure 2 shown. Figure 2 The carbon in the crucible is because of the excess carbon (negative electrode). The purpose of the excess is to completely reduce the lithium cobalt oxide to cobalt. The two can be separated by mature and simple magnetic separation to obtain cobalt with higher purity. The separated carbon can be used as a reducing agent again. According to the XRD results, its main components are Co and C, and CoO, Co2O3 and Li2O are not detected, indicating that the reaction in the crucible has basically occurred completely and the lithium oxide has completely entered the gas phase. XRD detection of the gas phase, such as Figure 3 As shown, its main component is Li2O, and other components are not detected, indicating that the purity of Li2O is high.

[0044] Example 2

[0045] A method for recovering valuable metals from a lithium cobalt oxide battery comprises the following steps:

[0046] Step 1: Mix the positive electrode material and the negative electrode material of the lithium cobalt oxide battery to obtain a mixture, wherein the mass ratio of the positive electrode material to the negative electrode material is 27:1.

[0047] Step 2, placing the mixture under a system pressure of 95Pa, heating to 1550K and keeping the temperature for 140 minutes, after the reaction is completed, recovering the solid phase containing elemental cobalt and recovering the gas phase containing lithium oxide at 1142K, thus completing the recovery of valuable metals.

[0048] Example 3

[0049] A method for recovering valuable metals from a lithium cobalt oxide battery comprises the following steps:

[0050] Step 1: Mix the positive electrode material and the negative electrode material of the lithium cobalt oxide battery to obtain a mixture, wherein the mass ratio of the positive electrode material to the negative electrode material is 24:1.

[0051] Step 2, placing the mixture under a system pressure of 50Pa, heating to 1400K and keeping warm for 100 minutes, after the reaction is completed, recovering the solid phase containing elemental cobalt and recovering the gas phase containing lithium oxide at 1172K, completing the recovery of valuable metals.

[0052] Although the present invention has been described above by combining with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the claims.

Claims

1. A method for recovering valuable metals from lithium cobalt oxide batteries, characterized in that: The following steps are involved: Mixing a positive electrode material containing lithium cobalt oxide and a negative electrode graphite material of a lithium cobalt oxide battery, and adding anhydrous ethanol to obtain a mixture; The mixture is placed under a system pressure of 10Pa~100Pa, heated to 1300K~1600K at a heating rate of 8℃ / min~12℃ / min, and then kept warm for 100min~150min. After the reaction, the solid phase containing elemental cobalt and the gas phase containing lithium oxide are recovered at 1132K~1217K to complete the recovery of valuable metals.

2. The method for recovering valuable metals from lithium cobalt oxide batteries according to claim 1, characterized in that: The amount of anhydrous ethanol added is 1 / 10~1 / 3 of the mass of the mixture.

3. The method for recovering valuable metals from lithium cobalt oxide batteries according to claim 1 or 2, characterized in that: The method also includes heating the mixture to 1053K~1093K at a heating rate of 8°C / min~12°C / min after obtaining the mixture, keeping the temperature for 25min~35min, and then heating the mixture to 1300K~1600K at a heating rate of 8°C / min~12°C / min.

4. The method for recovering valuable metals from lithium cobalt oxide batteries according to claim 1 or 2, characterized in that: The mass ratio of the positive electrode material to the negative electrode material is 32:1~16:

1.

5. A system for recovering valuable metals from lithium cobalt oxide batteries according to claim 1, characterized in that: comprising an outer body and a reactor, wherein The outer body includes a collecting chamber, a reaction chamber arranged at the lower part of the collecting chamber, and a flow channel arranged between the collecting chamber and the reaction chamber; The reactor is placed in the reaction chamber. After the reaction of the positive electrode material and the negative electrode material mixture of the cobalt oxide lithium battery is completed in the reactor, the gas phase containing lithium oxide enters the collection chamber through the flow channel for recovery, and the solid phase containing elemental cobalt remains in the reactor.

6. The system for recovering valuable metals from lithium cobalt oxide batteries according to claim 5, characterized in that: The radial diameter of the collecting chamber is larger than the radial diameter of the reaction chamber, and the radial diameter of the reaction chamber is larger than the radial diameter of the circulation channel.

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