Your Resources, Your Future
Cornwall's Geo-Resources
Metals for a Green Future
Metals are chemical elements that occur naturally in minerals within rocks. So what are elements, rocks, and minerals?
The number of metals we use in technology has been increasing over the years, and modern high-tech green energy solutions can require tens of different metals in their manufacturing. Take wind turbines for example:
As global demand for technology metals soars, some are in critically short supply. They are only found in a few types of rocks in a few places and if a new source is found, it can take many years to open a new mine and exploit that resource. This means production can become dominated by a single country (see map below), making the global supply vulnerable to political instability. Ultimately, these factors could prevent the world from reaching its climate targets, so it's really important that we find new and reliable supplies of technology metals.
European Commission, Study on the EU’s list of Critical Raw Materials (2020)
Geo-Resources in the SW
The geological history of the Cornwall and Devon involved plumes of molten rock cooling deep within the Earth to make what are now the granites of Lands End, Carnmenellis, St Austell, Bodmin and Dartmoor. These hot rocks and the Devonian sediments that interacted with mobilised metals which cool in veins that miners call lodes. Since the Bronze Age, people have been mining the region for a variety of metals, especially Tin (Sn), Copper (Cu), Arsenic (As), Zinc (Zn), Silver (Ag) and more recently, Tungsten (W) and Lithium (Li).
Credit Eva Marquis, licenced under CC-BY 2.0
This has resulted in an extensive underground network of tunnels, shafts and addicts below Cornwall and West Devon. Here you can see an animation of mine workings under the Camborne district:
Although mining helped build the historic wealth of the South West region, the legacy of that mining is not always positive. Mine wastes can be rich in toxic metals, which can pollute ecosystems and endanger wildlife. The extensive tunnels can make building in mining areas challenging and it has left many scares on the landscape. Now scientist, companies and the government are trying to make sure that future mining in the region has only a positive legacy.
Modern Cornwall's Mining Map
Use the map below to explore some of the mining, remediation, research and mineral exploration projects taking place in modern Cornwall.
Future Frontiers
Digital Technologies - Novel Extraction - Circular Economy - Environmental Remediation
Below is a showcase of research from the Cambourne School of Mines / University of Exeter. Research showcased here is led by Prof Karen Hudson-Edwards, Dr Rich Crane, Dr Laura Newsome and Prof Frances Wall.
All content below is distributed under a CC-BY 2.0 licence.
Digital frontiers
Studying mine wastes with satellites and drones
Researcher: Richard Chalkley
Since the invention of photography, people have been interested in taking images from the air, using cameras mounted on kites, balloons, pigeons (yes, really...) and eventually airplanes.
Now we use the latest satellite and drone technology to capture images.
Sensors and cameras attached to drones can be used to map mine waste at a fine scale.
Use the slider to see how iron concentrations (red = high iron) change across the Wheal Maid mine site.
This is an example of how drone imagery can be used to detect deposits of potentially useful and or problematic iron deposits. Once located, we can either treat it, or process it to recover economic metals.
New extraction technologies
Electro-mining and new solvents
Researcher: Dr Yujie Yan
Mine tailings (see example in picture) often contain heavy metals. This can make them environmentally dangerous, but also a valuable resource if the metals can be recovered.
In this experiment we are using specially designed solvents along with electricity to extract metals from the waste.
Electricity can drive heavy metal ions out of mine tailings, and the metals are collected on metal plates.
In this image you can see copper collected on the electrode after an experiment (where it's turned red).
With a combination of solvents and electricity, heavy metals are collected, and environmental risks are eliminated. The metals recovered can then be used in manufacturing.
Bioleaching for Lithium
Researcher: Becca Kirk
The principles of bioleaching involve the use of microbes in metal release by oxidation (loss of electrons) of specific elements in the mineral solution.
Fundamentally, providing iron is present in the minerals (which in many cause is true!), there's an opportunity to try bioleaching.
Many lithium bearing minerals are suitable for trying this, however there is some other factors which can make bioleaching less easy than it sounds!
Here the set up is reasonably simple with no need for elevated temperatures or shaking. However these microbes like an acidic pH, which requires constant monitoring.
We add things like elemental sulphur or acids to keep the pH at about 1-2. This is about as acidic as stomach acid!
It can take a long time to bioleach lithium from ores - for some it can take up to a year to get most of the lithium out! However, as a low energy low-cost solution this may be viable for 'wastes' or other materials such as batteries to get as much lithium as possible for green applications.
The Circular economy
Recycling and repurposing wastes: making best use of our resources
Waste to riches: the case of green rusts
Researcher: Jody Grasby
Geobacter sulffurreducens is a bacteria known to reduce Fe(III) (this means it gives electrons to the iron). It uses the energy released when it does this to grow.
Physical contact of the bacteria on an iron mineral is required for Fe(III) reduction to Fe(II)
Fresh mine water treatment waste from Wheal Jane had Geobacter sulfurreducens added to it. It changed from a brown sludge to a green material after a few weeks.
The result was the formation of more Fe(II), so Fe(III) reduction had occurred.
The green material formed is known as 'green rust'.
Green rusts are mixed-valent iron oxides which means they contain both Fe(III) and Fe(II).
They are double hydroxide minerals that contain both Fe(II) and Fe(III) hydroxide layers with anions and structural water interlayered between the cations.
The green rust formed in the experiment was Fe(II)4Fe(III)2(OH)12CO3·3H2O
Green Rust are useful because they can reduce contaminants, such as chromate, uranium, copper, gold and nitrate.
The contaminants are transformed into less mobile (or less soluble) and less toxic forms while green rust oxidizes into Fe(II) minerals.
Getting metals out of mine waste
Researchers: Dr Carmen Falagan Rodriguez, Dr David Dew
Making waste safe
Cobalt in mine waste
Researcher: Gabriel Ziwa
Poldice Mine is one of the oldest and most important documented mine sites in Cornwall. Ore extraction for tin, copper and other minerals such as cobalt dates as far back as 16th century.
Although mining and mineral processing stopped in 1930, the Poldice mine site is still dotted by tailings (wastes).
These tailings contain several elements including tin, copper, arsenic, and cobalt.
In this project I quantify the concentrations of these elements, and estimate how much of them is in a form that can be absorbed by the body if humans inhale dust from the site.
We found that 28% of the cobalt, 73% of the copper, 3% of the tin and 100% of the arsenic are in a form that can be easily taken up by the body if they are inhaled.
These results highlight arsenic and copper as the most problematic elements likely to cause environmental issues.
Legacy Waste in the Coastal Zone
Researcher: Dr Patrizia Onnis
The legacy waste projects studies waste of different types that we disposed of for centuries in coastal areas. The wastes are a results of coal and metal production (coal, slag, and mining waste) and the garbage produced by the household (municipal solid waste).
Lot of these wastes have been forgotten about, or cover by soil, vegetation, or buildings. It is hard to find them and to get chemical information about them. By sampling wastes, we found that the waste can hold various contaminants that can be toxic for the environment.
The picture here shows recent municipal waste covered by soil
The waste location (where are they hiding?) and chemical composition (what are they made off) are important information to protect our coasts (beaches, estuaries) where humans, animals, and plants live. The project is providing tools to environmental authorities to better understand this issue.
Here we're making measurements to see if waste upstream is affecting water quality in the estuary.
Our planet is warming up and sea levels are rising. This means the coastal line is changing, eroding or being covered by the sea water. Our project studies the interactions between waste and the changing environments.
Arsenic in rivers and estuaries
Researcher: Elin Jennings
Mine waste has been dumped in rivers for hundreds of years with no environmental management.
This waste is left to pollute the surrounding environment and still does to this day.
The waste can contain a high amount of toxic pollutants such as arsenic, copper, zinc, and lead.
These pollutants can be stored in ochre (red mud seen in the image).
High rainfall can release pollutants easily (shown in video) and carry pollutants downstream to the coastal zone.
Elin's research looks into how this waste is still polluting the coastal zone and how climate change will impact this pollution.
Manganese oxides in waste treatment Researcher: Peirou Li
Manganese oxides have many uses.
They can be highly absorbent for pollutants.
We are investigating how they might be manufactured and used to decontaminate soil and water.
