What happens when batteries are recycled?

We've all got a drawer of them at home, but how are batteries recycled? We asked John Redmayne, Managing Director, and Mario Champagne, Chemical Process Engineer – Circular Economy Engineering, at ERP. 

Q - How common are the various types of portable batteries and what are they used for?

Non-rechargeable and rechargeable portable batteries have many different chemistry types.

The most common batteries are alkaline/zinc-carbon batteries, which can be found in many devices. Rechargeable batteries (technically called accumulators) are often lithium-ion batteries which are used to power handheld electronics, as well as mobile phones, laptops, and power tools or lead-acid batteries which may be found in big electric toys, motorised wheelchairs, or on boats. Non-rechargeable lithium batteries are less common but can be used, for example, in remote locking systems for cars. Button cell batteries (silver-oxide and zinc-air batteries) are most commonly used in very small devices.

Battery collection stats 2022 ERP Typical mix of chemistries in mixed portable batteries (2022)The most commonly collected type of waste portable battery in the UK is alkaline (single-use) batteries –but it is important to collect and recycle all types. The 2022 data (see table) comes from one of the collection/sorting companies used by ERP in the UK. 

Q - What happens to the different battery streams following collection and sortation?

After collection, batteries are sorted manually and automatically by chemistry type. With efficiency levels of almost 98 per cent, automatic sorting – which uses sensors and specialised software – has become very sophisticated.

The sorted batteries are stored and carefully identified to avoid further mixing. Lithium batteries need to be handled with care to avoid damaging them, and because arcing can occur if the batteries have any residual energy (‘arcing’ is the condition when electrical charges use an air gap between two electric conductors to travel – creating a spark). That is why those batteries are typically stored in drums or containers layered in dry sand or vermiculite.

Q - Where and how are they reprocessed?

Each battery type goes to a facility where they can recover the embodied valuable materials through separation techniques based on material properties and capture any pollutants and heavy metals.

BatteriesHere are some examples of how the chemistry types are treated:

  • Alkaline/zinc-carbon batteries are shredded to separate the paper, plastics and metal from the black mass core.

  • Mercury batteries are heated at high temperatures to evaporate and condense the mercury further.

  • Nickel-cadmium, nickel-metal hydride and lithium batteries are processed at high temperatures in thermal vacuum vaporisation units, where the precious metals are evaporated and then condensed.

  • Lead-acid batteries are treated in the UK by smelters that process end-of-life car batteries. The batteries are crushed to recover the sulphuric acid, plastic and metal; lead is recovered in lingots.

Q - What secondary materials are recovered from the different types of batteries and what applications can they be used for?

Here are some examples of which materials are recovered and how they are used:

  • The iron in all battery types is recovered to make new goods.

  • The manganese oxide inside alkaline batteries is processed in a rotary kiln to recover the zinc oxide, which can be used as an additive in numerous products including plastics and ceramics.

  • The cadmium recovered from nickel-cadmium batteries is used to make new batteries.

  • The nickel in nickel-metal hydride batteries is recovered to make steel.

  • Cobalt, nickel and copper can be recovered from lithium batteries.

  • Mercury is recovered from mercury cell batteries and the decontaminated steel fraction is used to make steel.

Q - Have there been any important recent developments in battery recycling?

Given the importance of critical raw materials, research and development teams are developing processes to extract these valuable resources from batteries.

‘Black mass’ is a term used to describe the mixture of materials that remains after the recycling process of some types of batteries. Some recycling companies in Europe have developed ways of separating manganese and zinc metals from the remaining black mass by electrolysis, but this procedure is still costly and now rarely used.

Others have developed ways to avoid shredding, and separate the anode and cathode parts of batteries quickly and easily, and some enterprises have developed processes to transform the black mass from alkaline batteries into fertilisers.

One significant development is the emergence of recycling technologies that allow for the recovery of a wider range of materials from batteries. For example, new techniques are being developed to recover cobalt, a valuable material used in the production of lithium-ion batteries. This can reduce the reliance on mining for new cobalt and provide a more sustainable source of the material.

Another development is the growth of closed-loop recycling systems, where materials recovered from old batteries are used to make new batteries. This helps to reduce the environmental impact of battery production and encourages a circular economy for battery materials. Repurposing of tested and validated waste lithium-ion batteries to create power supply banks has been a recent innovation  – and with the significant growth in the numbers of electric vehicles on our roads, the research, development and building of more facilities to repurpose/recycle lithium-ion batteries are receiving considerable attention.

Finally, there are also initiatives focused on improving the collection and recycling of batteries. For example, the UK government has introduced regulations that require all large retailers that sell batteries to provide free in-store collection points for used batteries, making it easier for consumers to recycle their batteries.

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