Abstract: Taking the environmental impact assessment of a new lithium-ion battery electrolyte project as an example, through the specific process contained in the research project, the pollution links that may occur in each process are analyzed, and the “three wastes” and noise pollution that may occur in the project are carried out. Forecasting and evaluation, and corresponding pollution prevention measures were formulated. It is intended to provide reference for pollution source analysis and environmental protection measures for other projects in the industry.
Keywords: environmental impact assessment; environmental protection measures; lithium ion battery electrolyte
CLC number: X703
Document code: A Article ID:1674-9944(2016)24-0072-03\u003c Br\u003e 1 Introduction
As the country vigorously promotes the development of new energy industry, new energy vehicles are experiencing explosive growth, and the production and sales volume of new energy vehicles are increasing year by year. At the same time, 3C consumption of smartphones, tablets, mobile power supplies, etc. The steady growth of electronic products and energy storage batteries has driven the market demand for key materials such as lithium batteries and electrolytes. Electrolyte is one of the four key materials of lithium-ion battery. It plays an ion-conducting function between the positive and negative electrodes of the battery, and plays an important role in regulating the performance of the electrode/electrolyte interface. It can be described as the "blood" of lithium-ion batteries . The electrolyte is generally prepared from high-purity organic solvents, electrolyte lithium salts, additives and other raw materials under certain conditions and in a certain ratio. It is of great significance to study the environmental impact assessment of lithium-ion battery electrolyte construction projects to improve the environmental protection level of the industry.
This paper takes the environmental impact assessment process of a new lithium-ion battery electrolyte project as an example. Through the specific process included in the research project, the pollution links that may occur in each process are analyzed, and the “three wastes” that may be generated in the project and Noise pollution is predicted and evaluated, and corresponding pollution prevention measures are formulated.
2 Process and pollution production
The electrolyte product is a formula product, which is formulated into a product by using a carbonate solvent and electrolyte in a certain proportion. The production process of this project mainly includes the processes of adsorption, blending, packaging, etc. The whole process belongs to the physical process and does not involve chemical reactions. The process flow is shown in Figure 1.
2.1 Preparation of Electrolyte
The purchased carbonate solvent, propyl propionate, methyl propionate, ethyl propionate and other raw materials are transported through a closed pipe to the fine metering tank of the main workshop of the electrolyte. Pumps are injected into their respective adsorption columns, and the water in the solvent is absorbed by the molecular sieve in the adsorption column. The process is a physical adsorption process, and a molecular sieve with polarity is used to adsorb the polar impurities in the solvent to achieve purification of the product. Purpose; After that, the solvent is filtered through a precision filter to filter impurities (molecular sieves, etc.), and the purified electronic grade solvent is pumped into the mixing tank through a transfer pump. A certain amount of electrolytes, additives and special solvents are added according to the formula in the mixing tank. The liquid raw materials are transported by a transfer pump, the powdery raw materials are transported with a small amount of nitrogen, and the raw materials are stirred in a stirred tank for 7 h. The pump is driven into a precision filter. After filtering, the electrolyte is pumped into the finished product tank, and finally the finished product tank is pressed into the finished packaging tank through the quick joint. Because the electrolyte is strictly water-free, the entire production process is completely sealed, and the system is protected by nitrogen seal. The air release body generated by the processes of adsorption, preparation, metering, etc., and the exhaust gas generated by the filling process enter the exhaust gas treatment system through the closed pipe.
2.2 Molecular Sieve Regeneration
After the molecular sieve absorbs saturation, the organic component is volatilized in the molecular sieve to be volatilized and recycled, and the organic waste gas generated during the regeneration process enters the tail gas treatment device.
2.3 Washing bucket
The enterprise electrolyte is packed in 200 L stainless steel drum. The stainless steel barrel recovered after export is refilled by the enterprise after cleaning. Internal cleaning: firstly measure the recycled special packaging drum, then press about 0.5 kg of dimethyl carbonate solvent into the barrel, roll it on the drum machine for 20 minutes at a constant speed, and then press the solvent in the drum. Transfer to the corresponding collection container. The venting waste generated by the washing tub enters the exhaust gas treatment system through the closed pipe. External water washing: The label on the stainless steel drum of the electrolyte project needs to be removed by the worker's hand and then cleaned with water so that the label can be re-labeled at the factory.
3 Environmental protection measures and main environmental impacts
3.1 Exhaust gas
The exhaust gas produced by this project is mainly composed of nitrogen-sealed protective gas venting waste gas and molecular sieve regeneration tail gas (main component is nitrogen, the main pollutant is carbonate) It is composed of five parts: the organic waste gas of the class and propionate), the volatile waste gas of the quick joint, the cleaning waste gas on the inner wall of the packaging barrel, and the breathing exhaust gas of the storage tank of the raw material tank. The main pollutants are organic esters of carbonates and propionates. All exhaust gases are collected and processed into a catalytic combustion (CO) unit, and the exhaust gas is discharged through a 30 m high exhaust cylinder. The VOCs emission standards refer to the implementation of the Tianjin local standard "Control Standards for Volatile Organic Compounds in Industrial Enterprises" (DB12/524-2014).
The catalytic combustion treatment device treatment process of this project greatly reduces the temperature of oxidative decomposition of organic matter and reduces the energy consumption of the system through the action of the catalyst. The pollutants in the exhaust gas of this project are mainly esters, and do not contain catalyst poisoning. Substance, catalysts with higher catalytic efficiency for esters can be selected to improve the oxidative decomposition efficiency, and the catalytic combustion temperature is lower than that of thermal incineration, which reduces the formation of nitrogen oxides. CO furnace (catalytic combustion furnace) purification principle: Catalytic combustion is achieved by means of a catalyst at a low temperature (200 ~ 400 ° C), to achieve complete oxidation of organic matter, therefore, low energy consumption, easy operation, safety, high purification efficiency. The compact combination of the system makes full use of the heat source, saving equipment investment and operating costs. The process equipment maximizes the utilization of the calorific value of the organic components in the organic waste gas during operation , and the process flow is shown in Figure 2 below.