button battery cr1620.Waste battery recycling technology

　　The current situation of batteries used in China The most commonly used industrial battery in China is lead-acid battery. Lead accounts for more than 50% of the total battery cost. It mainly uses fire method, hydrometallurgical process and solid-phase electrolytic reduction technology. The shell is made of plastic and can be recycled, basically achieving no secondary pollution. Currently, the most commonly used small secondary batteries are nickel-cadmium, nickel-hydrogen and lithium-ion batteries. The cadmium in nickel-cadmium batteries is one of the heavy metal elements strictly controlled by environmental protection. The organic electrolyte in lithium-ion batteries, nickel-cadmium and nickel-hydrogen batteries The alkali in the battery and heavy metals such as copper, an auxiliary material for making batteries, all constitute environmental pollution. The total number of small secondary batteries currently used in China is only a few hundred million, and most of them are small in size. The utilization value of waste batteries is low, and their use is scattered. Most of them are treated as domestic waste. There are costs and management aspects to their recycling. There are also certain technical problems in recycling. Civilian dry batteries are currently the most widely used and most dispersed battery product, with an annual domestic consumption of 8 billion units. There are mainly two series: zinc-manganese and alkaline zinc-manganese, as well as a small amount of zinc-silver, lithium battery and other varieties. Zinc-manganese batteries, alkaline zinc-manganese batteries, and zinc-silver batteries generally use mercury or mercury compounds as corrosion inhibitors. Mercury and mercury compounds are highly toxic substances. When waste batteries are incinerated as domestic waste, some of the heavy metals such as Hg, Cd, PB, and Zn in the waste batteries are discharged into the atmosphere at high temperatures, and some become ash, causing secondary pollution. There are generally three internationally accepted methods of disposal of used batteries: solidification and deep burial, storage in waste mines, and recycling.

　　1. Solidify, bury deeply, and store in abandoned mines. For example, a factory in France extracts nickel and cadmium from it, then uses the nickel for steelmaking, and the cadmium is reused for the production of batteries. The remaining types of waste batteries are generally transported to special toxic and hazardous landfills. However, this approach is not only too expensive but also causes waste, because there are still many useful substances that can be used as raw materials.

　　2. Recycling

　　(1) Heat treatment There are two factories in Switzerland that specialize in processing and utilizing old batteries. The method adopted by Butterek Company is to grind the old batteries and send them to the furnace for heating. At this time, the volatilized mercury can be extracted. At higher temperatures, zinc Also evaporates, it is also a precious metal. Iron and manganese fuse to form the ferromanganese alloy required for steelmaking. The factory can process 2,000 tons of waste batteries a year, and can obtain 780 tons of manganese ferroalloy, 400 tons of zinc alloy and 3 tons of mercury. Another factory extracts iron directly from batteries and sells metal mixtures such as manganese oxide, zinc oxide, copper oxide and nickel oxide directly as metal scrap. However, the heat treatment method is more expensive, and Switzerland also stipulates that each battery buyer charges a small fee for the processing of waste batteries.

　　(2) "Wet treatment" A "wet treatment" device is being built in the suburbs of Magdeburg. Here, except for lead-acid batteries, all types of batteries are dissolved in sulfuric acid, and then various metals are extracted from the solution with the help of ionic resins. The raw materials obtained in this way are purer than heat treatment methods, so they sell for higher prices on the market, and 95% of the various substances contained in the battery can be extracted. Wet processing can eliminate the sorting process (because sorting is a manual operation, which will increase costs). The Magdeburg unit has an annual processing capacity of 7,500 tons. Although its cost is slightly higher than the landfill method, precious raw materials will not be discarded and the environment will not be polluted.

　　(3) Vacuum heat treatment method The vacuum heat treatment method developed by the German Alt company is even cheaper, but it first needs to sort out the nickel-cadmium batteries from the waste batteries. The waste batteries are heated in a vacuum, and the mercury evaporates quickly, and they can be After recycling, the remaining raw materials are then ground, a magnet is used to extract the metallic iron, and nickel and manganese are extracted from the remaining powder. The cost of processing one ton of waste batteries is less than 1,500 marks! View the article Waste Battery Recycling Methods of Waste Batteries 2007-01-2616:002.1 Current Situation of Waste Battery Recycling The most commonly used industrial battery in China is lead-acid battery, and lead accounts for the total number of batteries The cost is more than 50%, mainly using fire method, hydrometallurgical process and solid-phase electrolytic reduction technology. The shell is made of plastic and can be recycled, basically achieving no secondary pollution. Currently, the most commonly used small secondary batteries are nickel-cadmium, nickel-hydrogen and lithium-ion batteries. The cadmium in nickel-cadmium batteries is one of the heavy metal elements strictly controlled by environmental protection. The organic electrolyte in lithium-ion batteries, nickel-cadmium and nickel-hydrogen batteries The alkali in the battery and heavy metals such as copper, an auxiliary material for making batteries, all constitute environmental pollution. The total number of small secondary batteries currently used in China is only a few hundred million, and most of them are small in size. The utilization value of waste batteries is low, and their use is scattered. Most of them are treated as domestic waste. There are costs and management aspects to their recycling. There are also certain technical problems in recycling. Civilian dry batteries are currently the most widely used and most dispersed battery product, with an annual domestic consumption of 8 billion units. There are mainly two series: zinc-manganese and alkaline zinc-manganese, as well as a small amount of zinc-silver, lithium battery and other varieties. Zinc-manganese batteries, alkaline zinc-manganese batteries, and zinc-silver batteries generally use mercury or mercury compounds as corrosion inhibitors. Mercury and mercury compounds are highly toxic substances. When waste batteries are incinerated as domestic waste, some of the heavy metals such as Hg, Cd, PB, and Zn in the waste batteries are discharged into the atmosphere at high temperatures, and some become ash, causing secondary pollution. 2.2 Recycling Technology of Wasted Dry Batteries a. Manual sorting and recycling technology generally involves classifying dry batteries and then performing simple mechanical cuts to manually separate zinc sheets, plastic covers, carbon rods, etc., and residual Mn02, manganite and other mixtures Send it back to the brick kiln for calcination to make dehydrated Mn02. This method is simple and easy to implement, but it takes up a lot of labor and has little economic benefit. b. Fire recycling technology generally classifies and crushes dry batteries and then sends them to a rotary kiln. At a high temperature of 1100 to 1300 degrees Celsius, zinc and zinc chloride are oxidized into zinc oxide and discharged with the flue gas, using a cyclone dust collector. To recover zinc oxide, the remaining manganese dioxide and manganite enter the residue, and then further recover manganese and other substances. This method is simple and easy to implement. Generally, smelters can recover zinc without adding additional equipment. c. Wet recycling technology is based on the principle that zinc and manganese dioxide are soluble in acid. After classifying and crushing used dry batteries, they are placed in a leaching tank, and dilute sulfuric acid (100~120g/L) is added for leaching to obtain zinc sulfate. Solution, metallic zinc can be obtained by electrolysis. After the filter residue is washed and separated to separate the copper cap and carbon rod, the remaining Mn02 and manganite are calcined to obtain Mn02. The methods used include roasting-leaching method and direct leaching method. Compared with the fire method, the wet method has the advantages of less investment, low cost, fast factory construction, high profit, and flexible process, but it cannot guarantee the complete recovery of harmful ingredients.

　　3. Prevention and control of secondary pollution during the recycling process of waste batteries. The above three recycling methods are all simple and easy to implement, but each has its own shortcomings, and there is the problem of secondary pollution. Through a large number of experimental measurements, we have obtained feasible methods for preventing and controlling secondary pollution. method. First, the used dry batteries are classified, and after being cut open mechanically, the copper caps and zinc sheets are separated, which can be recycled separately. After magnetic separation to remove iron from the remaining carbon bag material, it is soaked in water at a solid-liquid ratio of 1:4 for 1 hour. The supernatant liquid is taken for evaporation and crystallization. The main components of the precipitate are Mn02, MnO(OH), and acetylene black. , carbon rods and other substances are added to the rotary kiln and refined to 600 degrees Celsius. The generated flue gas can be condensed to obtain a condensate, which can be cleaned regularly to obtain pure mercury. It also prevents mercury vapor from polluting the environment. During the calcination process, a large amount of acetylene black and carbon in the mixture reduce MnO2 to MnO. The reaction process is as follows: 2Mn02+C--->2MnO+C02. Add this calcined product into a sulfuric acid solution with a concentration of less than 2 mol/L at a solid-liquid ratio of 1:4, and soak it at a temperature of 80°C for 1 hour. The following reaction occurs: MnO+H2S04--->MnS04+H20 obtains manganese sulfate salt solution. At the same time, other soluble heavy metal sulfates will also be introduced. The obtained zinc skin, copper and other metals can be directly remelted and utilized. Ammonium chloride can be made into fertilizers or purified as chemical reagents. Manganese sulfate is a hormone component for animal and plant growth and can be used as a drying agent for paints and inks and in some organic synthesis reactions. As a catalyst, it is also used as a reagent for the production of paper, ceramics, printing and dyeing, and electrolytic manganese. Table 1 shows the composition of recyclable materials from zinc-manganese dry batteries. This recycling method requires less investment, uses simple equipment, and is easy to implement in small and medium-sized cities, thus eliminating the problem of transporting used batteries. The solution after recycling the used batteries is concentrated and reacts with EDTA to form a metal complex, which can completely eliminate secondary pollution. It has been determined that the amount of heavy metals contained in the solution after recycling waste batteries complies with national environmental protection standards. To separate these metals, they can be classified based on their different stabilities. Table 2 shows the complexation stability constants of metal ions and EDTA.

　　4. Problems and suggestions in the recycling process of used batteries

　　① Batteries cannot be disposed of after recycling and are generally piled. Batteries may leak or toxic substances may spread during stacking.

　　② Due to the wide variety of batteries and many counterfeit products, it also brings difficulties to battery recycling. Some batteries are mercury-containing batteries, some are cadmium-containing batteries, some use ammonium chloride as the electrolyte, and some use chloride. Zinc is an electrolyte, so it is recommended that manufacturers use unified standards to identify the type of battery and its main ingredients for recycling.

　　③ Strengthen the development of high-performance, environmentally friendly batteries and achieve mercury-free batteries for ordinary civilian use.

　　④The state should provide policy support for the recycling and disposal of waste batteries.

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