Researchers in Japan are proposing more localised recycling for obsolete alkaline batteries using small-scale microwave technology.
The report from academics at Ritsumeikan University, published in the Resources, Environment and Sustainability Journal, says lab-based experiments using pyrometallurgical microwave-based heating successfully separated Mn3O4 and ZnO contained in obsolete alkaline batteries and recovered manganese oxide and zinc separately, achieving a recovery rate of 97%.
It was also found that the recovery rate of zinc obtained by this method was 50% better that using conventional electric furnace-based heating, with less than half the heating time required.
‘The efficiency of the conventional centralised recycling system is based on its ability to treat a large amount of waste at the same time at a low cost per unit output. However, this is also associated with massive energy consumption for the transportation of waste at the collection stage and its transportation to the recycling facilities.’
The authors identified 1 710 municipalities and regions in Japan which would have the largest positive effect from adopting a distributed recycling system in terms of energy reduction.
‘It was found that energy consumption and GHG emissions can be annually reduced by 25 300 GJ and 1.54 Gg-CO2eq by adopting a well-balanced harmonisation between centralised and distributed recycling system for obsolete alkaline batteries in Japan. The method in this study can be readily implemented in any city for the adoption of a distributed recycling system.’
The researchers say their study can be considered as a starting point to explore the distributed recycling system for metal recovery with the use of microwave irradiation.