Small scale recycling process for spent alkaline batteries: Technoeconomic analysis and potential use of solar energy

Abstract

While alkaline battery is the one that dominates portable battery market in Australia, its recycling rate is far from sufficient. In the current work, small-scale carbothermic process to recover high value zinc/zinc oxide (Zn/ZnO) powder from spent alkaline black mass is studied. The study involved experimental investigation, process modelling that includes thermodynamics and mass and energy balance calculations, and techno-economic analyses. Continuous and batch-type process plants; as well as adoption of solar energy were considered in the study. It was found that Zn/ZnO recovery process is economically viable at the current Australian annual black mass production (200 tonnes/year) with a minimum annual income and IRR value over 20 years plant lifetime of AU$509,742 and 19.1%, respectively. A minimum capacity of 100 tonnes/year is expected to ensure that the process is economically favourable. The application of concentrated solar energy, however, enables the batch process to be carried out at a much lower capacity of 15 tonnes/year. The results of this study can be extended to better inform the feasibility of a small-scale process in countries other than Australia.