Specialised recycling flows of batteries
All batteries aren’t recycled together in one big process. Instead, they’re separated by their chemistry and go through specialised recycling flows to extract specific metals, compounds and other key materials found in different battery types.
For any particular battery chemistry there are several different recycling methods used around the world today. In order to paint a clear picture of such a diversified industry, we’ve created a generalised (and simplified) recycling overview that covers the majority of common recycling steps. Depending on the battery chemistry, some steps may be skipped, added, or repeated where appropriate, but the general processes used remain the same.
Step 0: Sorting and preparation
After collection and sorting, each stream is sent to a specific recycling partner who specialises in recycling one or more battery types.
Some recyclers have a preparation phase to check the incoming sorted batteries for any waste or impurities in the stream. This may also include washing / pre-treating the batteries in some way.
Input: Batteries from sorting facility
Outputs:
Some used batteries still contain a lot of electric charge, which can be hazardous during later stages of the recycling process. For this reason, most batteries are fully discharged and the electricity is converted to heat, ensuring a safe working environment for the rest of the process.
For small portable batteries, this usually involves submerging the batteries in a brine liquid (a salt water solution) at room temperature, though other methods exist such as submerging them in liquid nitrogen, or discharging them through pyrolysis.
Some recyclers discharge batteries through an electrical load, allowing them to recover the residual energy left in the battery. However, this only makes economic sense for larger batteries like those found in electric vehicles. The practice of recovering electricity from used cells is mostly an academic one for now.
Input: Sorted batteries
Outputs:
Depending on the machinery used for the comminution phase, it may be necessary to control the speed at which batteries enter the machine, as well as the orientation of the batteries upon entry.
This is generally done with either a step-loading system or a vibrating system which slowly orients and moves the batteries at a controlled speed toward the next step - comminution.
Step 1: Comminution
Comminution is the process of breaking down material, especially minerals or metals, into small particles or fragments. For larger batteries, this process is often preceded by dismantling to the module or cell level, allowing the individual components to be handled more safely and efficiently.
The resulting mixture is commonly referred to as black mass, which contains the internal electrochemical components of the battery.
At this point the polymeric or metallic material that forms the outer shell of the battery has been removed through comminution and various separation steps, leaving behind the internal electrochemical components - the black mass. These components vary significantly from one battery type to another, so the recycling process gets more specialised from this point onward. However, some form of metallurgy is almost always the next step in the process.
Step 3: Metallurgical distillation
Metallurgy is a branch of science and technology concerned with the properties of metals and their production and purification. This is usually achieved through pyrometallurgy, hydrometallurgy, or a hybrid approach.
In direct recycling processes, however, these metallurgical steps are minimised whenever possible, aiming to recover valuable materials more efficiently while reducing energy use and environmental impact.
Step 4: Output
With all viable materials separated from one another, the final stage in recycling batteries is sending off processed streams for use in factories, metal works, external purification facilities, and general re-use. This is different for each material in each recycling facility around the world. Local organisations might require lead ingots or pellets, 99% pure metals or alloy mixes that can be used for various construction purposes, and so on. Some less useful material ends up as fuel for smelting and furnaces.
Supply and demand, along with local government legislation and ethical / environmental targets, determine the final output of any given recycling process.
Below is an outline of the potential elements that can be recycled per battery type in %.
| 23,75% | Iron | Recycling |
| 5,01% | Non-ferrous metals (zinc and copper) | Recycling |
| 21,13% | Waelz oxide in function of zinc production | Recycling |
| 4,02% | Carbon (acts as a reductant in the process) | Other material recovery |
| 11,67% | Slugs (disposed) | Landfill disposal |
| 6,41% | Plastics (burning with energy recovery) | Energy recovery |
| 2,34% | Electrolyte (burning with energy recovery) | Energy recovery |
| 25,67% | Recycling slugs | Recycling |
| Total = 100% | Total useful appliance | 88% |
