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Recycling of Lead Acid Batteries - What's Involved

written by: Chief Engineer Mohit Sanguri•edited by: Lamar Stonecypher•updated: 10/1/2010

Lead Acid battery recycling is a technological difficult process yet most rewarding. In America it enjoys a rate of over 97 %. The lead produced by recycling is costing only 30 to 40 % of the mining costs for producing virgin lead, but it is the same. THe various parts of the battery recycled are ..

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    Why Recycle?

    We read a lot about lead-acid batteries recycling and how it is the most successful recycling program in America, where over 97 percent of lead acid batteries are recycled. But the question is why should we recycle or dispose of batteries correctly and not throw them out with our common household trash. The answer is that because lead is toxic.

    Carelessly disposed batteries may end up in solid landfills where the lead may leach out to the environment. The effects of lead on the human body are plenty and painful. It can cause miscarriage in pregnant women, reduce sperm production, and damage the nervous system. Severe exposure can damage the brains and kidneys, causing death. Children are more sensitive to this damage than adults and no safe blood lead level exists for them. Lead is a cumulative poison, which means it keeps on adding or accumulating in our body and ecosystem upon exposure and causes ill health.

    The fluid (electrolyte) in batteries is corrosive and can cause loss of eyesight if the battery explodes (which it can very easily if the negative and positive electrodes come in contact with each other). The plastic used in the casing also is not biodegradable and it is a good idea to recycle it.

    The recycling of batteries gives extension to the limited resources of the earth, reduced monetary cost of lead production (around 35 % of mining costs), and energy conservation. Finally because they are classified as hazardous waste under the Hazardous Waste Act of 1989, they cannot be disposed of in normal garbage.

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    Bulging of Lead Acid Battery

    Battery Condition
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    What components are reclaimed?

    Virtually all of the lead-acid battery is recycled, apart from the impurities and alloying metals that are removed as dross. The plastic casing or poly- propylene is broken into pieces, melted, and re-cast as pellets that are sold again to battery manufacturers. The lead is melted and turned into ingots that are resold to the manufacturers and also for other applications. The electrolyte may be reclaimed or neutralized and released into the municipal sewers.

    Plastic: The electrolyte of the battery is drained and the battery casing along with the lead is crushed in a crusher and then fed to a water tank. The lead, being heavy, falls to the bottom and the plastic is separated. The poly propylene is then cleaned and washed. Thereafter it is melted and made into symmetric pellets and used as feed for making new plastic casings. The black color of the plastic casings is indicative of its being recycled.

    Lead: All the lead parts and the compounds are cleaned and then melted. The alloying elements and other impurities float on top and are called dross, which is skimmed. All other materials and metals other than lead (except uranium) float on top. The molten lead is then cast into ingots.

    Electrolyte: The electrolyte in a lead-acid battery is sulfuric acid dissolved in water. This is handled in two ways depending on the plant. One method is to neutralize it chemically and release it as water. The second method is to convert it to sodium sulfate and make detergent from it. Under no circumstances it must be allowed to leak into the ground water.

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    Value of Old Battery

    Lead has a high price on the market and sells at a profit after recycling. Also recycled lead is up to 60% cheaper than mined lead. It also saves our environment as lead is not dumped into it. In many countries like India, old batteries are sold to the scrap dealers at a price. In the end the dealers, recyclers, and the battery manufacturers are at a benefit as they get lead and plastic at a cheaper rate. In the end whether we receive a monetary benefit from recycling or we give a small sum, recycling is favorable to us as it allows us to dispose of the batteries correctly without harming the environment and our children.

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    References

    Practical Action - Recycling Used Lead-acid Batteries

    Planet Ark - Recycling Week - Lead-Acid Battery Recycling Fact Sheet (PDF)

    Battery Council International - Battery Recycling

    Centers for Disease Control - Toxilogical Profile for Lead (PDF)

    GTZ Partnerschaft mit Afrika: Neue Perspektiven, Fundamentals of the Recycling of Lead-Acid Batteries (PDF), Dr.-Ing. Heino Vest

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    Image Credit

    Taken by Mohit Sanguri, Chief Engineer, of emergency batteries of a Panamax ship which were not replaced in eight years.