10 minutes with… Bramley Murton on deep-sea mining

Materials World magazine
3 Jul 2017

Natalie Daniels catches up with Bramley Murton at the Deep Sea Mining Summit to discuss the opportunities and challenges within deep-sea mining. 

Tell me about your background.

I studied geology at the University of Edinburgh, UK, and a PhD at the Open University. I am Associate Head of Marine Geosciences at the National Oceanography Centre in Southampton, leading the marine minerals team. Over the past 20 years, I have led numerous research programmes including studies of mid-ocean ridge volcanism, hydrothermal activity and seafloor mineralisation. In 2010–13, I was chairman of the international consortium for mid-ocean ridge research, InterRidge. I sit on the executive board of the EC-funded programme Blue Mining, developing technologies for seafloor mineral exploration, assessment and extraction. I am also Chief Scientist for the international research project MarineE-tech, studying critical elements in ferromanganese-cobalt-rich crusts on the deep Atlantic seafloor. I also lead the development of the use of autonomous underwater vehicles in extreme environments.

What does the Marine e–tech project involve?

MarineE-tech addresses a new supply of rare and scarce elements such as tellurium, cobalt and the heavy rare earth elements from deep-sea ferromagnesian crust deposits. These electronic technology (E-tech) elements are critical to high technology and low-carbon energy production. The mineral deposits constitute the single largest resource of E-tech elements on Earth. MarineE-tech pursues this research through engagement with the offshore survey and mining engineering industries as well as researchers in biology, geology, geophysics, oceanography, microbiology and marine chemistry across the UK and Brazil. It aims, across both local and trans-ocean scales, to assess resource potential, processes of mineral formation and environmental impacts of future exploitation.

You found tellurium at concentrations 50,000 times higher than in deposits on land. How could this be explored further?

We have developed an exploration methodology, using sonar to map underwater mountains called seamounts to identify potential sites of ferromanganese crust formation. The resulting maps and acoustic images show us where to explore in more detail. For this, we deploy an autonomous underwater vehicle that dives for 24 hours and maps and images the seafloor. The vehicle takes thousands of photographs as well as detecting the composition and temperature of the seawater. On the basis of the new maps and images we then deployed a remotely operated vehicle to take hundreds of samples and drill cores from across the 40km-wide seamount. The water depths range from 1,000–4,000m and the seafloor is very rugged, like any mountain, with deep valleys and cliffs. We also map the currents and tides around the seamount and, together with geology maps, we can predict where mineral-rich crusts are abundant. 

This approach can be used anywhere and will most likely be adopted by deep-sea mineral exploration globally. Tellurium is a key component in thin-film high-efficiency photovoltaic cells (in the form of cadmium-telluride). If we want to move towards a low-carbon future, then we need raw materials like tellurium. We calculate that based on the average concentration of tellurium and thickness of the ferromanganese crusts at tropic seamount, if all the tellurium was used to make solar PV panels, they could provide up to 60% of the UK’s electrical energy generation capacity.

Can you ensure deep-sea mining operations cause little damage?

This is an area of ongoing research. For biology that is directly impacted by deep-sea mining plant, there is total destruction. However, it's a matter of assessing the importance of that impact – at a species level, are we going to loose species or just individuals? When we cut down pine trees for timber, it may be bad news for the tree, but has little impact on the species of pine. Of course, if it's a major isolated tree that hosts lots of other life whose felling would cause a great loss of biological diversity, then you have to think twice. Another way to look at this is on the seafloor – the seamount we studied is only 40km in diameter. As such, if it were mined, it would impact only 10,000th of 1% of the Earth’s surface. In contrast, farming impacts 40% of all land and cities 3%. On a practical level, if deep-sea mining happens, then we must devise methods to minimise impacts. Sediment plumes are one threat to life beyond the mined area, so real-time monitoring of their dispersion is essential. Developing new ways to minimise plume production is required, and how to filter and return water produced at the surface vessel.

Human life needs raw material to survive. Population continues to grow and societies to develop. As land-based grades diminish, and the resource gap grows, despite recycling and the circular economy, new sources of materials have to be found. The question is whether deep-sea resources can provide a safer and less harmful supply compared with land-based mining. 

Should deep-sea mining be explored?

What is needed is a comprehensive test site where we can focus our R&D efforts and conduct scientific experiments with all the stakeholders. If we can bring together industry, science, social scientists and humanities to address the concerns and potential benefits of deep-sea mining, then we can begin to answer that question. In the high seas, all seafloor mineral exploration is controlled by the United Nations’ International Seabed Authority and only national governments can hold licenses for mineral exploration in these areas, so the governments need to conduct the appropriate experiments and ensure all parties can come together to gather the information required to ensure any deep-sea mining is environmentally sustainable.

What are the challenges of the deep sea?

The extreme nature of the environment. It is cold under high pressure, dark and corrosive, with no wireless communications or satellite navigation. For mineral deposits that are on or near the seafloor, we have to devise remote-sensing methods of exploration. We need new geophysical systems to detect and image the deposits on and under the seafloor – this is time consuming and costly. There is a need to develop new robotic systems and better understand the processes by which the mineral deposits are formed and preserved.

What’s next?

Developing an effective exploration and assessment strategy and an efficient, reliable mining technology. There are valid concerns about environmental impacts of deep-sea mining, so a testing mining observatory to ensure the industry can develop a sustainable business model and collaborative development is required. Can we develop technologies to minimise impact, maximise effectiveness and derive a baseline of information to inform policy makers and ensure best practice? Only when the regulatory environment and technology are right, and society can be reassured that it is safe, will the industry develop.