Editors: | F. Kongoli, H. Dodds, M. Mauntz, T. Turna, K. Aifantis, A. Fox, V. Kumar |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2019 |
Pages: | 112 pages |
ISBN: | 978-1-989820-11-7 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Abstract
The recovery of Pb from the spent lead-acid battery paste is achieved conventionally through pyrometallurgical processes. This process requires relatively high temperature (~1,100 °C) for the decomposition of PbSO4 which is a dominant compound in the paste along with PbO2, PbO, metallic Pb and other impurities. The high-temperature pyrometallurgical process releases SO2 gas and Pb particulates into the environment, raising serious environmental concerns. The hydro-electro metallurgical process, which has been developed as an alternative, also consumes high energy and uses toxic acids like HBF4 or H2SiF6. The need for an eco-friendly and cost-effective recycling process for the recovery of spent battery paste [1,2,3,4], is not only critical but also very timely. Indeed, the market size of secondary lead-acid batteries is forecasted to reach over $95 billion USD by 2026 [5]. Within this market, the recycling of lead-acid batteries is a revenue stream worth around $14-16 billion USD by 2025 [6].
In this paper, we present our work towards a fully hydrometallurgical, eco-friendly and cost-effective process. The recovery of Pb is achieved through the synthesis of ultrapure lead-citrate, which is obtained directly from spent lead-acid battery paste via desulphurisation and treatment with organic acids. Unlike previous iterations of this process, we have optimised the conditions to achieve production of ultra-pure lead-citrate, 99.99%, with minimum consumption of reagents. This paper shows how it is possible to minimise production costs for the recycled lead compounds to the extent that the process is as cost-effective, if not superior economically, when compared to the incumbent technology. The scalability and economic improvement of the latest iteration of this now-patented hydrometallurgical process greatly facilitate the globalisation of this innovative technology.
Keywords
Lead, battery, recycling, lead citrate, hydrometallurgy, organic acids