Q&A Processing Waste Batteries

Each battery chemistry has a different process, and some may even have a choice of processes.

There is not space or time to go into detail here of all the processes available. The choice comes down to one of cost versus recycling efficiency – the more material you recover for re-use the more it costs.

The batteries directive will stipulate an efficiency that must be reached, which is likely to rule out some of the more inefficient (but cheaper) processes.

The pre-treatment stage is to remove the steel case or plastic outer pack of the batteries, so that the metal-containing inner parts can be processed.

The two basic processes are:

Pyrometallurgical – where the batteries are put in a furnace to extract some of the metals, and

Hydrometallurgical – where the contents of the batteries are dissolved in acid and the metals recovered chemically

For alkaline and zinc carbon batteries, which are the most common types, the UK hasn’t got a full process yet, but we are developing a hydrometallurgical system.

The reasons for this are:

• Hydrometallurgy can readily achieve the recycling efficiency target expected to be set by the directive.
• The hydrometallurgical process is very flexible; it is easy to increase the size and throughput of the process as volumes grow, whereas furnaces are of a fixed size.
• There are few emissions to atmosphere with a hydrometallurgical process, where as a furnace will always have gaseous emissions (CO2 etc).
• There are still small amounts of mercury in some very old batteries, and it is much easier to cope with mercury in the cold hydrometallurgical process, than in the hot processes.

Each battery type has its own constituents; the key ones are:

• Alkaline/Zinc Carbon containing Steel, Manganese, Zinc
• Li-ion rechargeable containing Steel, Cobalt, Nickel, Copper 
• Nickel Cadmium containing Steel, Nickel, Cadmium 
• Nickel Metal Hydride containing Steel, Nickel, Cobalt

As to what these metals can be used for, the list is endless – more batteries certainly, and most of the others tend to get used in the steel industry – see steel facts and figures below.

These trials will determine the real (full) cost of collecting waste portable batteries and sorting them into the different chemistry types ready for recycling.

In future battery “producers” will be responsible for the cost of battery recycling.