The need to reduce energy demand is felt most keenly in the energy intensive industries (EEIs), of which the manufacturing of metals such as iron and steel, as well as non-ferrous metals, are a large constituent. The lead industry has in the last few decades developed effective processes for the recycling of metallic lead from (principally) lead acid batteries. The batteries are crushed (to remove the plastic), desulfurised, smelted and then refined to produce lead bullion which can be reused to make new batteries. Whilst very high rates of recycling are achieved, the entire process in very energy intensive, mainly from the milling and the smelting but also from the need to eliminate any lead-to-air emissions. Whilst the principles of this pyrometallurgical process have remained relatively unchanged for centuries, this proposal seeks to develop a novel solution-based electrochemical route to lead recycling using deep eutectic solvents (DESs).

Deep eutectic solvents have been applied to a number of different technological applications, owing to their relatively low cost, ease of handling, low environmental impact and, most importantly, their ability to dissolve a wide range of inorganic compounds - including oxides. We propose to dissolve lead paste - from lead acid batteries - in DESs and design novel electrochemical cells for the extraction of high purity metallic lead. This will be done in conjunction with Envirowales Ltd, a lead-acid battery recycler, as our project partner.

The main objective of the project is to develop a new electrochemical technology for lead-acid battery recycling based on a solution-based processing. We aim to understand the behaviour of speciation of Pb within the solvent, as well as the effects of secondary cations and electrode poisoning. We aim to design and build a number electrochemical cells (from bench-top to pilot plant prototype), that will replace the smelting steps in the current high temperature process. This will be supported by accurate total energy modelling of the current pyrometallurgical process with which to benchmark our energy gains by switching to the new technology. We envisage that not only will this technology have a lower overall energy demand, but will also be cleaner, due to a significant reduction in lead-to-air emissions.

Potential Impact:
This project has secured the support of a UK-based secondary lead production company (EnviroWales Ltd) thus ensuring that the project team have excellent opportunities to maximise the commercial impact of this research. The outputs from the collaboration will help establish a strong UK business opportunity centred on the design, manufacture and utilisation of an emerging and highly versatile electrochemical technology. This would contribute to the growing increasing lead-acid battery market, which is currently worth over $30 billion, and projected to be $50bn by 2020. We are also developing a technology that has the added benefit of reducing the environmental issue to lead-to-air emissions from lead smelting.

As well as the direct economic impact of this work, there will be further academic impact, with the research team contributing to the scientific literature through high impact publications and presentations at many international conferences, such as the Materials Research Symposia (in both Europe and USA), Electrochemical Society meetings and also more technical lead-acid battery and market-orientated conferences.

A key aspect of our programme is the interaction with our industrial partner EnviroWales Ltd. They are providing us with waste battery material so the development of our process is based upon real feedstocks. They will also allow us full access to their plant to perform detailed process analysis of their current energy demands and efficiencies, as well as engaging with the project at our advisory board, and general industrial expertise. We will also provide training for three postdoctoral researchers who we would expect to go on to become research leaders in their field, providing direction to this research area, whilst developing future directions. These researchers will also engage in training, through collaboration with the CDTs, with the next generation of researchers, providing clear pathways to secure the future of this research area in the UK.

We will be fully engaged with the End Use Energy Demand Centres around the UK, participating in events and providing regular updates on our progress, and demonstrating advances.

Intellectual property will be fully protected through discussion with Imperial Innovations, a subsidiary of Imperial College responsible for technology transfer, and patents filed where appropriate. In terms of the manufacturing aspects of this work we will explore any opportunities to spin-out companies to further develop the technology used in this project.