Batteries are used whenever electrical energy is needed but there is no direct connection to the public electricity grid. A battery can convert chemical energy directly to electrical energy. Depending on the battery system, this converting process is irreversible or reversible. When the process is irreversible, the battery is called a primary battery. The reversible batteries are called secondary batteries and can be recharged up to 1000 cycles (i.e. lead acid battery- checken). A lead acid battery is rechargeable and is commonly used as a result of its good properties like low maintenance and suitable for many purposes. Furthermore they are easily available and are relatively cheap.
Lead-acid batteries either start or power cars, trucks, buses, boats and trains all over the world. This usage is well known but during the last years another usage is increasing.
Solar panels are becoming cheaper and an enormous boost is seen in the adaption of solar applications in rural areas in developing countries where no electrical grid is available. As lead acid batteries are still the cheapest way to store energy, almost all these solar applications contain a lead acid battery.
However, lead is a very toxic metal and once the battery is not useful anymore, it is of the utmost importance that proper collection and recycling takes place. In order to effectively understand the issues about lead acid batteries in the solid waste stream and the benefits of diverting them to recycling, it is important to know some technical aspects of the lead acid battery, the public health and environmental risks associated with disposing of them, recycling methods and relevant legislation developed to minimize risks involved with the use and recycling.
The battery lifetime is defined as the period of time in which a battery is capable of being recharged and retain the charge applied. Once the battery is no longer capable of being recharged or cannot retain its charge properly, its lifetime reaches its end and it becomes a ‘used battery’ for the application it was designed for.
The lifetime of a lead acid battery is very dependent on its rate, conditions and kind of use. It is estimated to be between 1 up to 5 years.
Returning used lead acid batteries to the recycling loop has a long tradition. Thanks to the compactness of the battery, its high lead proportion and relatively high metal prices, it has been worthwhile for consumers to return their own or collected car batteries to the scrap trade or secondary smelters. This is also the case in low-income countries and return rates of up to 80% can be achieved normally through an informal collection system of scrap dealers, secondary lead processors and consumers.
Why recycle lead acid batteries?
The benefits of recycling of lead acid batteries are numerous. Unless we recycle used batteries certain toxic components pose a potential risk to the environment and human health. Moreover recovering scrap batteries has the advantages that it is easier and much less energy intensive than producing new lead from ore (the production of recycled lead requires 35-40% of the energy needed to produce lead from ore). Recycling also reduces dispersal of lead in the environment and conserves mineral resources for the future when done in a proper way.
However recycling of used lead acid batteries according international guidelines is not a simple process which can be done in small scale enterprises. Certain measures need to be taken to prevent negative impact to people and environment.
Used acid lead batteries must be collected, transported and stored with proper care, in order to avoid adverse health effects and environmental contamination. Special measures need to be taken at collection points and batteries should NEVER be drained at collection points as no guarantee can be given for safe treatment of the sulphuric acid with all hazards involved with the drainage to health and environment.
The recycling technology
The recycling process can be divided into three major processes:
- Battery breaking
- Lead reduction
- Lead refining
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