Last updated on April 4th, 2018
Battery recycling process divert batteries from landfills and to recover metals and other materials.
Batteries consist of heavy metals and toxic chemicals. Therefore, battery disposal in landfills along with municipal waste can have severe impacts on ground and water.
There are several categories of batteries, most of which are recyclable. The main categories of batteries and their recycling processes are presented below.
1. Lead Acid Batteries
Lead Acid Batteries is one of the most common types of batteries. Indicatively but not limited, this category includes car and motorcycle batteries, UPS batteries and other commercial batteries.
Undoubtedly, it is the easiest type of batteries to recycle and recover lead, plastic and sulfuric acid. The simple and cost effective process to recover lead multiple times constitutes this type of battery recycling the most widespread in the world. Currently it is estimated that 98% of all lead acid batteries are recycled.
Lead acid batteries recycling process
In the beginning of the recycling process, a hammer mill is used to break apart the lead acid batteries. Following, the broken battery pieces end up to a vat, where plastic is separated from the metals. More specifically, plastic floats whereas lead and other metals sink to the bottom of the vat.
Plastic is then removed, dries and sent to a recycling center for reprocessing. In most cases the recovered plastic is used for new battery cases, with the process to continue for several times.
The lead concentrated in the bottom of vat is sent to smelting furnaces, where it is poured into ingot molds. Any impurities floating are removed with a scraper when lead is still molten. After cooling, ingots are removed from the molds and are forwarded to battery manufacturers, who will re-melt them and produce new batteries.
With regard to the sulfuric acid included in the batteries, neutralization is the most common practice applied. If necessary, the neutralized water is treated and tested to meet clean water standards. Alternatively, the acid is treated and converted to sodium sulfate, a substance that has multiple uses in glass, textiles and detergent industries.
An increasing problem of our days is the mix of lead acid with Li-ion batteries. Increased attention is needed since this mixture can lead to critical incidents such as explosions and injuries.
- Sulfuric acid
2. Nickel-Cadmium Batteries
Nickel-Cadmium batteries belong to the category of rechargeable batteries. Despite being invented and used for more than 100 years, they have lost a big market share from other rechargeable batteries, such as NiMH and Li-ion batteries.
Nickel-cadmium battery recycling is important since in that way it is achieved their diversion from landfills. More specifically, if disposed in a landfill, the metallic shell will corrode and cadmium will escape. Consequently, cadmium will dissolve and will end up to water. Sadly, cadmium traces are already detected in oceans.
Nickel-cadmium batteries recycling process
A high temperature metal reclamation process is used to recycle Nickel-cadmium batteries. First all plastic parts are removed. Then the metallic parts are led to a furnace where all high temperature metals included in the battery (i.e. nickel, manganese, etc.) melt.
The molten metals end up to a bath where they solidify during casting. As for low temperature metals (i.e. cadmium and zinc), they are separated during the melting process.
- High temperature metals, including nickel, manganese, etc.
- Low temperature metals, including cadmium, zinc, etc.
3. Nickel-Metal Hydride Batteries (NiMH)
Based on their content, nickel-metal hydride batteries are considered semi-toxic. Despite this categorization, it is much preferable to drop off these batteries to your nearest drop-off bin rather than discard them with other household waste, even in small quantities.
Nickel-metal hydride batteries recycling process
Drying is the main element of NiMH batteries recycling process. More specifically, before the beginning of recycling process, all plastics are removed. Then a totally controlled drying process, in terms of temperature and time, is applied.
Drying is used to remove moisture from the batteries. The “moisture” comes from potassium hydroxide (KOH) electrolyte and H2O included in them. Following drying, battery cells are directed to alloy manufacturing or stainless steel industries.
4. Primary Lithium Batteries
Primary lithium batteries are also known as lithium-metal batteries. They own their name to metallic lithium which is their main constituent. Primary lithium batteries are mostly used in watches, hearing aids, sensors and memory backup as well as in military combat.
In terms of management, lithium metal batteries require special attention because they contain metallic lithium that reacts violently in contact with water or moisture.
If disposed in a landfill, escape of metallic lithium from crushed batteries most probably will ignite a fire. Landfill fires are difficult to handle and expose to great risk not only the environment but the whole landfill as well.
A very good way to avoid such incidents is to discharge fully the batteries prior to recycling.
It is highlighted that lithium-ion batteries for laptops and mobile phones do not contain metallic lithium.
Primary lithium batteries recycling process
First step of metallic lithium batteries recycling is to expose their content. This happens using either shredders or a high speed hammer according to the battery size.
The released content is then submerged in caustic water. This basic solution neutralizes the electrolytes, allowing the same time the recovery of ferrous and non ferrous metals.
The scrap metals recovered are sold to recyclers aiming to counterbalance the recycling cost of these batteries.
Following metal recovery the neutralized solution is filtered to recover carbon. The carbon recovered is pressed into sheets of carbon cake. Alternatively, cobalt can be used to recycle some of the carbon.
The lithium hydroxide in the solution is converted to lithium carbonate. Lithium carbonate is fine white powder which is used to produce lithium ingots and foil for batteries. In addition, it provides metal lithium for the manufacture of sulfur dioxide batteries.
- Ferrous metals
- Non ferrous metals i.e. manganese and nickel
5. Lithium-ion Batteries
Lithium-ion batteries may be considered almost harmless. However, their recycling is more than recommended because of the constantly increasing amounts generated.
Even though the value of the metals recovered may not cover in many cases the actual cost of recycling, environmental reasons require the recycling of Lithium-ion batteries.
Lithium-ion batteries recycling process
The Lithium-ion batteries recycling process applied, is the same applied in Nickel-Cadmium batteries.
- Ferrous metals
- Non ferrous metals, i.e. cobalt and aluminum
6. Alkaline Batteries
Alkaline batteries are called the batteries that rely on the reaction between zinc and manganese oxide. Rechargeable alkaline batteries allow reuse of specially designed cells.
Having lowered their mercury content in 1996, several authorities over the world allow their disposal in landfills. However, in regions such as California and Europe all batteries are considered hazardous waste and obey to special management rules.
Currently, recycling of alkaline cells is quite low, approximately four percent. However, efforts are made to increase this rate to forty percent by 2025.
Alkaline batteries recycling process
Alkaline battery recycling is a specialized mechanical separation process.
- Manganese concentrate
- Brass fractions.
All the recovered materials are reused in new products, to counterbalance the cost of the recycling process.
Where to recycle batteries?
Use the Recycling Center Locator to easily find the nearest place to recycle your used batteries.