In a recent study published in the Journal of Chemical Technology and Biotechnology, Canadian researchers developed a novel method for extracting and separating metals from spent alkaline batteries. This provides a promising approach for the effective recycling of essential materials.
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Batteries play an increasingly important role as the world's energy demands rise. However, because spent batteries contain metal, disposing of them improperly poses serious environmental risks. Recycling these metals offers a sustainable supply of valuable materials and reduces environmental risks.
The method for extracting potassium, zinc, and manganese presented is more affordable and energy-efficient than other approaches currently in use.
We focused on the extraction of the main minerals present in alkaline batteries because they represent more than 70% of the volume of spent batteries in North America. This research supports the principles of the circular economy, where materials are reused and recycled, creating a closed-loop system. This reduces waste and can lead to long-term economic sustainability by maximizing the utility of resources, which is one of the main objectives in current treaties such as the Paris Agreement.
Noelia Muñoz García, Researcher and Study Lead Author, Université de Sherbrooke
Importantly, efficient recycling of battery materials is critical to mitigating harmful environmental impacts.
The main problem of improper disposal of spent alkaline batteries is that compounds of potassium, zinc, and manganese can leach into the soil and pollute groundwater, posing threats to the environment and human health, such as ecotoxicity and abiotic depletion,” noted García.
The method relies on a procedure known as hydrometallurgy, or "leaching," which extracts the metals from aqueous solutions. Compared to techniques requiring high temperatures, hydrometallurgy is more energy-efficient because it can be done at room temperature.
The use of three distinct steps to extract the metals makes the process developed in this study novel. In other hydrometallurgical processes, all of the metals can be extracted in a single leaching step, but this results in a complex leachate composition that is expensive to break down into its constituent parts.
The cost of downstream purification was reduced by the researchers' ability to produce higher-quality leachates by removing the metals in three stages with various leaching agents. The procedure yielded an extraction efficiency of 86.1% for manganese and 99.6% for zinc overall.
The most important factor was to find a suitable leaching agent (in this case sulfuric acid) and a reducing agent (hydrogen peroxide), which increased the extraction of these minerals.
Antonio Avalos Ramirez, Study Corresponding Author and Researcher, Université de Sherbrooke
The researchers are currently planning to increase the extraction method's scale.
Ramirez noted, “‘The next steps will be to develop separation and purification units for obtaining zinc and manganese at a quality good enough to introduce them to the market and use them in the production of new goods. Further research is needed to address the scalability of the process at an industrial/commercial scale.’”
Journal Reference:
Garcia, M., N., et al. (2024) Extraction and separation of potassium, zinc and manganese issued from spent alkaline batteries by a three-unit hydrometallurgical process. Journal of Chemical Technology and Biotechnology. doi.org/10.1002/jctb.7649