Search for valuable metals gains £3 million boost

10 April 2017

A copper smelter

A copper smelter. Vast amounts of metals need to be found and processed to support society's technological lifestyle. © Djelen/Shutterstock.com

A Museum-led consortium has won a £3 million research grant to help predict where to find valuable metal ore deposits.

The grant, awarded by the Natural Environment Research Council (NERC), will increase geologists' understanding of the processes that lead to the formation of concentrated mineral resources.

'Rich deposits are scarce,' says programme lead Dr Jamie Wilkinson. 'If we can predict where to find them, then we can reduce the cost and environmental damage of prospecting.'

A copper cable factory

Over 18,000 million kilograms of copper are extracted from the ground every year, to be used mainly in electrical wiring and plumbing © Official/Shutterstock.com
 

Searching for hidden ore deposits

Our society depends on a reliable supply of metals to support our technological lifestyle. To match demand, exploration companies have to keep discovering new ore deposits that they can economically mine.

This is becoming more difficult because most of the ores exposed at the Earth's surface have already been found. Companies increasingly have to search for hidden deposits, concealed beneath up to a kilometre of barren rock.

Only about one in every thousand prospects explored by companies is eventually developed into a mine.

The Burj Khalifa megatall skyscraper in Dubai

Burj Khalifa in Dubai, the world's tallest residential building, is clad in stainless steel containing molybdenum. The addition of molybdenum creates ultra-strength steel. © ventdusud/Shutterstock.com

How ores form

An ore deposit is an accumulation of specific minerals that geological processes have concentrated into a relatively small volume of rock. Scientists do not completely understand why they form in some parts of the Earth but not others.

The research programme will investigate the geological processes that occur at subduction zones - regions of the Earth's crust where one tectonic plate descends beneath another, generating volcanoes and earthquakes. These areas, called volcanic arcs, produce some of the planet's largest accumulations of metals such as copper, gold, silver and molybdenum.

The ore formation process starts with molten rocks, or magma, deep in the Earth's mantle. The magma becomes enriched in certain metals and rises through the Earth's crust. At some point, the metals are transferred to water-rich liquids. As these liquids approach the surface, a series of physical changes and chemical interactions with surrounding rocks create the metal-rich deposits.

The Popocatépetl volcano

Popocatépetl, the second most active volcano in Mexico, lies above a subduction zone where one tectonic plate descends beneath another
 

But not all volcanic arcs produce rich sources of metals. Deposits often occur in clusters and in non-uniform patterns. Discovering why this happens will be a focus of the new research.

'A critical aspect for exploration is why ore deposits are so rare - only a very special set of conditions allow a typical arc magma to evolve to the point where an ore deposit can form,' says Dr Wilkinson.

'If we can understand why this happens, then we can make much smarter predictions about where undiscovered deposits of useful metals are likely to be located.'

Finding fertile areas of ore formation

To understand these critical conditions for ore formation, the project team is taking three approaches.

The researchers will analyse the chemical composition of minerals within solidified magmas, studying trace elements that may reveal more about the conditions under which the minerals formed.

They will also perform high-pressure and high-temperature experiments designed to simulate conditions deep within the Earth's crust.

Finally, they will develop computer models to explore the physics of how the magmas and metal-rich fluids migrate through the Earth's crust on their way towards the surface.

Ultimately, the researchers hope to develop better prospecting tools. Companies will then be able to analyse minerals in likely areas for telltale traces of the enrichment processes to confirm whether it is a good place to search for ore.

Molybdenite in a quartz vein

A sample of molybdenite in a quartz vein. Molybdenite, a compound of molybdenum and sulphur, is the primary source of the world's molybdenum.
 

Academics and industry working together

The multidisciplinary project involves most of the UK's experts in the field, hosted in eight of the country's universities and research institutes. There is also a diverse group of international scientific collaborators and the project is supported by several of the world's largest mineral exploration companies.

'This project bridges the divide between academic and industrial research in a way that is not normally possible through projects funded entirely by industry or entirely by government agencies,' says Dr Wilkinson.

'Not only will we understand more about the fundamental processes that go on inside the Earth, but we will help exploration companies find ores faster and with less environmental cost.'

  • By James McNish

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