Metals are essential components of almost all modern technology. Amongst these are the emerging technologies on which we are depending to tackle the Climate Emergency: electric motors, batteries, transformers, photovoltaic panels and catalysts, just to name a few.
Consequently, demand for 'green technology metals' (including Ni, Cu, Pd and Co) is surging, and is projected over the next 25 years, to eclipse the total for all previous human history. Recycling can only deliver a fraction of the supply. Even for metals such as Co, for which it is as high as 70%, it only accounts for 30% of demand. For metals which are more difficult to recycle, including Se, In and V, it remains <1%. It is therefore clear that the continued health and prosperity of both humankind and the natural environment depend on a huge increase in sustainable metal mining this Century.
Despite such urgency, our methodology for the extraction of metals from the subsurface hasn't changed since the inception of metal mining which marked the beginning of the Bronze Age; we still "dig up" the raw materials. This results in environmental damage on a truly global scale. Therefore, whilst the metals extracted may be used to build 'green technologies' the nature of their extraction, via energy intensive digging, haulage and crushing, means that there is considerable "embedded carbon" in all metal products. This is hampering our ability to address the Climate Emergency.
In fact, the situation is presently worsening, because as the near-surface ore deposits are being exhausted we are resorting to digging deeper into the subsurface (>1km depth in some cases) to reach them. The massive energy consumption involved is raising the degree of embedded carbon in humanity's metal supply, just at the time when we need urgently to reduce it.
This is a global problem but also one which is important for the UK. Burgeoning demand for green technology metals coupled with various shifts in geopolitical conditions have dictated that metal mining is back on the UK political agenda. The prospect of a mining renaissance, however, has attracted scrutiny from the general public who have expressed concerns that it will compound and reproduce the social and ecological damage that has been associated with extractive activities in the past. Indeed, the high population density of the UK and Europe demands radical new thinking into what technology is appropriate for the extraction of our metal resources. We need radical new thinking in how we extract metals from the subsurface.
This project seeks an entirely new approach to metal mining. In particular we will investigate the use of electricity and a suitable electrolyte (liquid that can carry dissolved metal ions) to decompose a metal-bearing ore deposit (to yield the desired metal) whilst it remains buried in the subsurface. Fundamental electrochemical theory suggests that this may be possible only using only a modest energy supply (i.e. of the same order of magnitude as can be supplied using a modest-sized array of solar panels). The metal laden electrolyte fluid will then be pumped to the surface.
We anticipate that this new method would be particularly applicable for an important class of minerals that comprise metals bonded with reduced sulfur, known as the sulfides. These are noteworthy for their ability to conduct electricity, which is a critical requirement. The sulfides are widely regarded as the most important type of ore and currently supply approximately >80% of all Cu, >70% of all Co, >60% of all Ni, >95% of all Zn and >99% of all platinum group metals.
This project will provide the fundamental "proof of concept" data for this radically new approach to metal mining. We anticipate several technical challenges, however if we are successful, then we could unlock an entirely new sustainable future.
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