Non-rechargeable batteries should not go in the rubbish, but how many of us have been guilty of throwing them in the bin. At last, it is compulsory in the UK for retailers who sell batteries to offer a recycling facility in shop. So now there is no excuse for people to throw them way.
Currently, the UK recycles a miserly 3% of old batteries, but the government hopes that the new legislation will mean that within 6 years the recycling rate is more like 45%.
This is a really good move by the EU as the batteries contain heavy metals that should be recycled. Once in a landfill the battery case corrodes, allowing the heavy metals to contaminate both soil and water. Many batteries contain cadmium which is toxic to aquatic vertebrates.Low levels that exist in water get magnified along the food chain, in a process called bio-accumulation. Unfortunately, the sight of a discarded battery lying on the sea bed is becoming more common, as shown in the photo below by Mark Caney. Mercury used to be a major problem, but most non-rechargeable batteries are now mercury-free, with the exception of button cell batteries.
There are many types of dry cell battery which contain different metals so they are recycled in different ways. NiCd batteries contain cadmium and iron-nickel which is recovered by heat treatment in the furnace. NiMH batteries are separated mechanically in a vacuum-chamber and the nickel re-used in the steel industry. Li-Ion batteries are treated by pyrolysis (very high temps) which separates out the metals. Mercury-containing button cells are processed by vacuum-thermal treatment which vaporises the mercury and then it is condenses back to a solid. The zinc-carbon and alkaline-manganese batteries are usually smelted and the metal recovered.