LR41 battery.Introduction to waste battery recycling technology

　　1. Zinc-manganese dry battery (1) Hydrometallurgical method This method is based on the principle that Zn and MnO2 are soluble in acid. Zn and MnO2 in the battery react with acid to form soluble salts that enter the solution. The solution is purified and electrolytically produced to produce metallic zinc and electrolytic MnO2. Or produce other chemical products, fertilizers, etc. Hydrometallurgy is further divided into roasting-leaching method and direct leaching method. The roasting-leaching method roasts waste batteries to volatilize ammonium chloride, mercury chloride, etc. into gas phases and recover them respectively in the condensation device. High-valent metal oxides are reduced to low-valent oxides, and the roasted products are leached with acid. , and then electrolytically recover the metal from the leach solution. The main reactions that occur during the roasting process are: MeO+C→Me+CO↑A(s)→A(g)↑The main reactions that occur during the leaching process: Me+2H+→Me2++H2↑MeO+2H+→Me2++H2O during electrolysis , the main reaction at the cathode: Me2++2e→Me The direct leaching method is to crush, screen and wash the waste dry batteries, and then directly use acid to leach the zinc, manganese and other metal components in them. After filtering and purifying the filtrate, the metals are extracted and chemical products are produced. . The reaction formula is: MnO2+4HCl→MnCl2+Cl2↑+2H2OMnO2+2HCl→MnCl2+H2OMn2O3+6HCl→2MnCl2+Cl2↑+3H2OMnCl2+NaOH→Mn(OH)2+2NaClMn(OH)2+oxidizing agent→MnO2 ↓+2HCl battery Zn is recovered in the form of ZnO. The reaction formula is as follows: Zn2++2OH-→ZnO2-→ Zn(OH)2 (amorphous colloid) → ZnO (crystalline) + H2O (2) Atmospheric pressure metallurgy method This method is a process of oxidizing, reducing, decomposing, volatilizing and condensing metals and their compounds in waste batteries at high temperatures.

　　Method 1: Heat used dry batteries at a lower temperature to volatilize the mercury first, and then recover zinc and other heavy metals at a higher temperature. Method 2: First roast at high temperature to volatilize the volatile metals and their oxides, and the residue is used as metallurgical intermediate products or processed separately. Hydrometallurgy and atmospheric metallurgy are relatively mature technologies for treating waste batteries, but they all have the common shortcomings of long processes, multiple sources of pollution, high investment and consumption, and low overall benefits.

　　In 1996, Japan's TDK Company made a bold reform in the recycling process, changing the recycling of individual metals into recycling to make magnetic materials. This approach simplifies the separation process and greatly reduces the cost, thus greatly improving the efficiency of dry battery recycling.

　　In recent years, people have begun to try to research and develop a new metallurgical method - vacuum metallurgy: based on the fact that each component of the waste battery has different vapor pressure at the same temperature, through evaporation and condensation in the vacuum, they can be processed at different temperatures. Separate from each other at high temperature to achieve comprehensive utilization and recycling. Since it is carried out in a vacuum, the atmosphere does not participate in the operation, so pollution is reduced. Although there is still little research on vacuum metallurgy and there is still a lack of corresponding economic indicators, it has obviously overcome some shortcomings of hydrometallurgy and atmospheric pressure metallurgy, so it will become a promising method.

　　2. Nickel-cadmium battery Ni-Cd battery contains a large amount of Ni, Cd and Fe, of which Ni is an important raw material in steel, electrical appliances, non-ferrous alloys, electroplating, etc. Cd is a rare metal used in batteries, pigments, alloys, etc., and it is also a toxic heavy metal. Therefore, Japan has carried out research and development on the recycling of waste nickel separator batteries at an early stage. The process also has two types: dry method and wet method.

　　The dry method mainly takes advantage of the high vapor pressure of cadmium and its oxides to evaporate cadmium and separate it from nickel at high temperatures. The wet method is to crush the waste batteries, leach them with sulfuric acid, and then use H2S to separate the cadmium.

　　3. Lead-acid batteries Lead-acid batteries are larger in size and have strong lead toxicity. Therefore, among all types of batteries, they are the first to be recycled. Therefore, their technology is relatively complete and is constantly developing. In the recycling technology of waste lead-acid batteries, the processing of sludge is the key. The sludge phases of waste lead-acid batteries are mainly pbSO4, pbO2, pbO, pb, etc. Among them, pbO2 is the main component, and its weight in the cathode filler and mixed filler is 41% to 46% and 24% to 28%.

　　Therefore, the reduction effect of pbO2 has an important impact on the entire recycling technology. There are two reduction processes: fire method and wet method. The fire method is to reduce and smelt pbO2 together with other components pbSO4, pbO, etc. in the sludge into pb in a metallurgical furnace. However, due to the generation of secondary pollutants such as SO2 and high-temperature PB dust, high energy consumption and low utilization rate, it will be gradually eliminated. The wet method is to add a reducing agent under solution conditions to reduce pbO2 and convert it into a low-valent lead compound. Many reducing agents have been tried.

　　Among them, the reduction of pbO2 with FeSO4 in sulfuric acid solution is ideal and has industrial application value. FeSO4 in sulfuric acid solution reduces pbO2. The reduction process can be expressed by the following formula: pbO2 (solid) + 2FeSO4 (liquid) + 2H2SO4 (liquid) → pbSO4 (solid) + Fe2(SO4)3 (liquid) + 2H2O. The reduction process of this method is stable, fast, and also It can completely transform the metallic lead in the sludge and facilitate the reduction of pbO2: pb (solid) + Fe2(SO4)3 (liquid) → pbSO4 (solid) + 2FeSO4 (liquid) pb (solid) + pbO (solid) + 2H2SO4 (liquid) ) → 2pbSO4 (solid) + 2H2O reducing agent can be prepared using steel pickling wastewater to treat waste with waste.

　　Ni-MH batteries and new lithium-ion batteries have been widely used with the development of handheld phones and electronic devices in recent years. In Japan, the output of Ni-MH batteries reached 18 million in 1992 and 70 million in 1993. By 2000, it accounted for nearly 50% of the market share.

　　It can be expected that in the near future, a large amount of waste Ni-MH batteries will be produced. The positive and negative electrode materials of these waste Ni-MH batteries contain many useful metals, such as nickel, cobalt, rare earths, etc. Therefore, recycling Ni-MH batteries is very beneficial, and their recycling technology is also being actively developed. With the development of science and technology, especially information technology, the world's demand for batteries will only increase rather than decrease. The resulting battery pollution and consumption of natural energy will also greatly increase. Although various recycling technologies are becoming more and more perfect, they only treat the symptoms but not the root cause. Therefore, scientists have proposed the development of new green batteries that are conducive to environmental protection and sustainable development.

　　New green environmentally friendly batteries refer to a type of high-performance, pollution-free batteries that have been put into use or are being developed in recent years. Metal hydride nickel batteries, lithium-ion batteries that have been widely used, mercury-free alkaline zinc-manganese primary batteries and rechargeable batteries that are being promoted and applied all belong to this category; polymer lithium or lithium-ion batteries and fuel batteries that are being developed Batteries, electrochemical energy storage supercapacitors, etc. can also be included in this category.

　　Since Pride invented the first lead-acid battery, chemical batteries have a history of 140 years, and their family has grown day by day. However, the resource consumption caused by mass production of batteries and the environmental pollution caused by waste batteries are also obvious to all.

　　As early as 1992, Agenda 21, adopted at the World Conference on Environment and Development held in Brazil, had clearly put forward the policy of sustainable development. Living in harmony with the earth and following the path of environmental protection and sustainable development are the general trends of industrial development. Strengthen the environmental management of waste batteries: Introduce corresponding laws and policies, continuously improve and develop waste battery recycling technology, expand the scope of recycling, and take corresponding measures, such as landfill disposal, even if there is no ability to process them.

　　Recycling technology should be developed in the direction of reducing costs and avoiding secondary pollution as much as possible. At the same time, we are taking the road of developing new green and environmentally friendly batteries: developing high-energy, pollution-free green batteries, and minimizing environmental pollution and resource consumption at the beginning of manufacturing. In this way, production and recycling can form a virtuous cycle, which can truly benefit the people without harming them and nature.

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