Lithium batteries are considered to be relatively environmentally friendly ways of storing energy, but will the discarded lithium batteries pollute the environment?
1, the status of waste lithium battery
As far as the actual situation is concerned, there are very few enterprises that recycle used lithium batteries. Since the scale of operations of general enterprises is relatively small, coupled with the backwardness of production equipment and production technology, the production of enterprises is only for the exploration stage, and Without actual production, there is no way to deal with discarded batteries. The most common method for disposing of discarded lithium batteries in China today is to mix the waste lithium batteries with some other solid waste and then incinerate them. As a result, the environment has caused extremely serious pollution. At present, with the continuous development of the lithium battery industry, some domestic experts have proposed a new method for disposal of waste lithium batteries.
Zhao Pengfei et al. proposed to use a machine to cut waste lithium batteries, and then classify the discarded lithium batteries by vibration and sorting methods, and then classify the positive and negative materials, electrode active materials, graphite and electrode active materials. And the electrode material is placed in a muffle furnace with 500 degrees Celsius for heat treatment, and then the lithium and cobalt oxides are sorted and recycled by flotation.
Chen Liang and others use H 2SO 4+H2O acid leaching electrode material, also using N 9O2To extract copper, precipitate aluminum with NaOH solution, and then use it to completely precipitate, and produce nickel-cobalt-manganese carbonate. The leaching rates of nickel, cobalt and manganese are 98%, 97% and 96, respectively. %, in summary, nickel, cobalt and manganese are all higher than 5%, with high recovery value and recycling effect.
Xu Yuan et al. used a different extraction method to extract and recycle the waste lithium cobalt oxide battery. In this process, the acid ion leaching method is first used to separate the metal ions in the cathode material, and then the magazine is used. 2O4Extract and remove, separately remove the Fe from the magazine 3+, Al 3+, Ca 2+, Cu 2+, and Mg 2+Ion, but Li still exists in the water 2+With Co 2+Ion, then you need to use P0 to remove these two ions, and also have to use HCl solution to back-extract CoCl in organic cobalt-rich 2By using a two-stage back extraction method, complete separation of ions can be achieved, leaving lithium ions in the water. Using Na 2CO 3Precipitating lithium ions can get Li 2CO3.
All in all, China produces a large number of lithium batteries, and the consumption of lithium batteries is relatively large. Although people pay more attention to the recycling of lithium batteries, they have not paid enough attention to the recycling and recycling of lithium batteries. The treatment of lithium batteries is usually handled in the same way as other common garbage. At the same time, people do not understand the way of recycling lithium batteries, so that the recovered lithium batteries can not be effectively applied.
2, waste lithium battery discharge treatment and manual disassembly
A waste lithium battery usually has a residual charge. In the process of processing the lithium battery, if the residual power is not released, it will easily cause fire and explosion during the battery splitting process. Therefore, Before the test of the discarded lithium battery, the discharge treatment of the waste lithium battery is required. The methods for treating the waste lithium battery are usually physical and chemical methods. The physical discharge method mainly discharges by means of an external load. The battery is connected to the external resistance, so that the remaining power is consumed during the exothermic process, but this method is suitable for discharging a small amount of batteries. The method of pretreating by discharging the sodium chloride salt solution is easy to operate, convenient and simple. The characteristics, and more economical and practical, will not produce secondary pollutants, so it is widely used in the discharge of waste lithium batteries.
In the experiment, firstly, the waste lithium battery should be placed in saturated brine to discharge it for 10 minutes. The short circuit of the positive and negative batteries will completely release the battery. The battery after the discharge is placed below 60 °C. Discharge in the drying box for 10h, and manually disassemble the outer casing of the lithium battery to obtain the inner core of the battery, and then manually sort the plastic film of the lithium battery and the positive and negative electrodes to obtain the positive electrode material.
3, analysis and control of pollutants in the process of recycling lithium battery resources
3.1, electrolyte pollution emission control
Electrolytic lithium batteries have strong volatility, high corrosivity, toxicity and flammability. The electrolyte is mainly composed of lithium hexafluorophosphate (LiPF6), which reacts with water and acid to produce toxic gases such as HF. As well as toxic substances, it produces fluorine pollution; usually, the electrolyte solution is a mixed solvent of EC+DMC and PC+DEC. These components are all flammable and explosive substances, and after they are released, organic substances are formed. Fluoride can be It reacts with NaOH to produce NaF. Therefore, NaOH solution is usually used when removing fluorine contamination. With manual disassembly, the electrolyte will volatilize, which is very inconvenient for collection, so it is difficult to carry out this work. .
Measures for handling the electrolyte: During the experiment, the lithium battery is manually disassembled under a closed ventilating kitchen, and the ventilating window is opened. After the battery is disassembled, the plastic film, positive and negative electrodes need to be quickly immersed in 0.5 mol. The NaOH solution removes the fluoride in the electrolyte after a certain period of time. Since the surface of the aluminum foil has an active material and lithium acetylene black cobalt oxide, in addition, it is necessary to dispose the NaOH solution with a dilute alkali solution, when the electrolyte is treated, There is no NaOH dissolved and discharged out of the aluminum foil. Therefore, after the electrolyte is precipitated, it is necessary to clamp the positive electrode with tweezers and dry it as an experimental material, but the volatilized part of the vinegar solution can be absorbed by the NaOH solution, and the treated tail gas needs to be used. The ventilated kitchen is discharged to the outside to protect the environment.
3.2, acid consumption and residual acid control
By H 2SO 4+H2O calculated that it was found that under the acid system, lithium was leached in the waste lithium battery, and the residual amount and consumption of the acid in the cobalt experiment can effectively reduce the acid emission by controlling the amount of acid leaching in the experiment, in this experimental process. In the calculation method of acid residual amount and consumption amount by means of neutralization titration, the optimal amount of leaching acid is calculated by taking different sulfuric acid concentrations as the basis for investigation.
Conclusion
Nowadays, due to the large amount of lithium batteries used in China, the scrapped amount of lithium batteries is also relatively large. In the waste lithium batteries, the recycling of lithium, cobalt and other metal ions has a high value. Therefore, it is necessary to make rational use of waste. Lithium batteries, in order to avoid pollution to the environment, the waste lithium battery to create certain economic benefits.
