Lead is the most efficient commodity metal to recycle, with over 99% of lead batteries collected and recycled in a closed-loop system in the EU and THE US. This is a higher recycling rate than any other mass consumer product, with 95-99% of discarded batteries being recycled in western countries. Batteries typically contain 65 percent lead, most of which can be recycled. Most of the waste collected comes from old car batteries and a small amount from industrial batteries. The process is designed to recover polypropylene housing material, but other polymers, such as acrylonitrile-butadiene-styrene or styrene-acrylonitrile used in industrial batteries, are generally not recyclable. If there is a large amount of industrial battery waste mixed together, the process of recycling other polymers may become economical. For industrial batteries, brass inserts, copper connectors and antimony alloys may also add value to scrap.
The recycling process starts with the battery breaking, crushing the battery so the acid is expelled and collected. The cells are then broken down into small pieces and the polypropylene is separated from metallic lead, battery paste and other plastics using a flotation process. Battery paste can use sodium carbonate to remove sulfur and acid into sodium sulfate for sale. Polypropylene is cleaned and sold for reuse. Lead paste and metal lead are then smelted with reducing agent and flux to produce lead ingots. It is then refined to remove impurities in order to produce pure lead of the desired purity. This may be provided in this form to battery production or alloy to customer specifications. The slag is smelted to recover metals such as antimony, tin and copper. Silver can also be recycled. The process is highly developed and efficient to implement.