From Wired UK:
Two companies are convinced that the historical mining region of Cornwall holds a bounty of lithium, but first they need to get to it
HIDDEN IN THE hills of St Dennis in Cornwall, a short drive away from the mining village once known as the richest square mile in the world, lies a gigantic hole in the ground. This is not unusual; the area is pitted with hundreds of old and abandoned mines where for almost 300 years tonnes of copper, tin, tungsten and clay were taken from the earth. What is odd, at least in 2021, is the noise coming from it: the steady sound of digging.
Finding the source of the sound involves a cautious ascent on a rocky path to the mouth of the Trelavour Downs, where dense vegetation gives way to a stark landscape ripped apart by heavy machinery. Entire chunks of land are missing, leaving behind white craters where hills abruptly turn into chasms. On a bright day, looking at the white walls is like gazing into the Sun.
In the midst of this scene on a Tuesday afternoon in April is an almost comically small red digger, chugging noisily away at a small hole in the ground. This, say hard hat-wearing geologists from lithium-extraction company Cornish Lithium, is the place that will herald a mining renaissance.
Cornish Lithium is one of two local companies – the other being British Lithium – that believe that this shiny metal could be a new gold rush for Cornwall; an opportunity to revive an industry that waned decades ago and left many of the traditional mining villages impoverished. But their mission is bigger than that: they think these deposits could unlock the UK’s electric dreams, making the extraction of lithium and manufacturing of lithium-ion batteries possible in the country for the first time, reducing the substantial ecological footprint of current battery technology. They believe there could be enough lithium in Cornwall to meet UK demand when the country moves from fossil fuel vehicles to electric ones – they just have to find a cost-effective way to get it.
IT'S THANKS TO the Cornish miners of the past that today’s companies know where to dig in the first place. To identify a potential site, Cornish Lithium geologist Adam Matthews painstakingly poured over aged maps drawn by hand, with scratchy letters showing the depth of each of the dig sites and what the miners found. Each borehole extends underground first vertically, then off in shoots, like the roots of a tree. While there are a lot of historical geological maps out there, he often found them in rather peculiar places. One treasure trove was in private hands, in the attic of an historic mining-enthusiast who had amassed a cache of them with a friend over the past 100 years.
The cost of digging blind would be prohibitive for a startup. To narrow their search, Cornish Lithium used machine learning to find patterns in the historical mining data, hoping to find lithium on the first try. They layered all of the maps on top of each other to create one master map, and worked to fill in the gaps in their knowledge – an endeavour that Matthews says took a year and a half.
“You might notice that the measurements are different here,” he says, pointing at one of the boreholes drawn on the maps in Cornish Lithium’s office in Truro, a few kilometres from the coastal town of Falmouth. “On these maps everything’s in fathoms [one fathom is 1.8 metres]. In some cases, but not all cases, they measure the distance of it inclined – whereas now you measure vertically. Depending on the year, they might have done one or the other.” He smiles: “You have to do trigonometry to figure it out.”
Sometimes, the map writers will try to tell you how deep a hole is, but won’t tell you where they started measuring from. He points to numbers scratched in ink on another map – “can you see here, 70 to 112?” The number 70, he explains, is what’s called the fathom level. “But it’s not the distance below the surface, it’s the distance below the ‘level’. But there is no standard measure for where the level is,” he says. “Think of it as the drainage in your house: it’s in a certain place, and it’s slightly inclined to allow it to drain… but it’s a very different place if it’s on a hill, or in a valley.” Underground, this means that the hole marked as 112 fathoms deep could end at a very different depth than what the map appears to suggest.
In some cases, past miners didn’t make records of where they decided to dig at all. There were huge black spots of information missing on mines that Cornish Lithium could unknowingly crash into, destabilising its plans, which Matthews says he only managed to shed light on thanks to consulting a former miner called Terry Cotton who had worked in the area for 40 years. Some of the mines marked on the map are comically shallow. “That’s probably people just having a go,” he says. Other people tried to reproduce maps and inserted errors “as they put their own spin on it”....
....MUCH MORE
