Extracting Metals from Magmatic Geofluids: New Early Research to Tap Energy and Critical Metals from the Metalliferous Magmatic Brines of Dormant Volcanoes

 

     Volcanoes have long been associated with valuable mineral and metal deposits. Volcanogenic massive sulfide deposits are a major source of these ores. The heat and pressure in the volcanic fluids rearrange molecules in the semi-solids, liquids, and gases and cause changes in those phases. These fluids also include subsurface water that may be heated by the adjacent geofluids, resulting in a hydrothermal system that fills nearby fractures or the porous spaces in nearby rocks with granular or fracture space for fluids, including sedimentary rocks. Most non-ferrous metals extracted around the world are linked to magma.   

     Researchers from the UK’s Oxford University are studying a dormant volcano on the Caribbean Island of Montserrat, with the goal of assessing the feasibility of extracting metals from the metals-rich geofluids under the dormant volcano. Generating geothermal heat and power would be a co-benefit of these kinds of projects. Research is in the early stages.

    

    In my deep dive into brine mining, I covered geothermal brines from sedimentary basins, or oilfield brines, and geothermal brines such as those from salar deposits which are concentrated brines under salt flats. Some of these such as the Smackover brine in Arkansas, Louisiana, and Texas, and brine which yields bromine in Japan, are also considered to be magmatic brines. According to Professor Stephen Sparks FRS from the University of Bristol:

 

“You can have groundwater leaching through cracks and permeable rock to form saline solutions, for example, and these brines could also be useful,” he says. “But magmatic brine forms from the magma itself.” Solid rock can contain water, such as in hydrated salts or that dissolved into the minerals that comprise the rock. When friction between tectonic plates melts rock to form magma, that water becomes part of a homogeneous molten solution. Through a series of complex geological processes associated with volcanic activity that take place over millions of years, mineral-rich brines accumulate in the sub-surface.”

 

“The liquid brine tends to lie two to four kilometres below the surface in lens-shaped deposits.”

 

     Geothermal drillers usually avoid areas with suspected magmatic brine. One reason is the heat. These geofluids may be too hot for conventional geothermal development. Research is ongoing with hot, supercritical geothermal brines. The image below is of a geothermal power plant in Japan that is being considered for supercritical geothermal development of deeper magmatic brines. In the 1990s a 3.7km test hole there in a granite found an unusually metal-rich brine at 520 degrees C. Since then, it has become cheaper and more technologically feasible to test drill supercritical geothermal but it is still in its infancy. The flow charts below show some of the advantages of extracting lithium from brines vs. mining hard rock for lithium.

 

     UK-based scientists Olivia Hogg and Jon Blundy writing for Geoscientist lay out their case for accessing magmatic brines for heat, energy, and metals:

 

“There is a growing awareness that magmatic brines have the potential to resolve the resource paradigm in which we find ourselves. Investing time in technological development and broadening our understanding of volcanic systems, including drilling into them, is central to evaluating how we can simultaneously harness geothermal power and metals, and so better equip us for the energy transition. In many ways, the storage of magmatic fluids in underground porous rock resembles oil-and-gas reservoirs, meaning that existing hydrocarbon expertise could be readily repurposed in the hunt for brine reservoirs.”

 

     It should be acknowledged that it could take many decades before the hotter magmatic brines and supercritical geothermal are tapped. Some, like the Smackover formation, which is being tapped now, is much cooler at about 150 degrees C. Accessing hotter geothermal has many challenges such as well integrity, O&M issues, scaling & corrosion, tool damage, and more. Some of these issues are more common with hotter metals-rich brines. Scaling can occur in the well as thr brines lose pressure and temperature so that they precipitate as scale as they come closer to the surface. Hogg and Blundy write:

 

“For example at Kakkonda, well-bore scales contain up to 13% per cent weight of copper, 20% zinc and 20 ppm gold, not to mention a wealth of other valuable metals. Ensuring that this polymetallic bounty is brought to the surface, rather than precipitating en route is crucial. Designing novel materials that can sequester metals from hot fluids at the bottom of the well, and development of well-casing materials that inhibit scale nucleation, are just two possibilities under consideration.”

 

They estimate that as many as 2000 dormant volcanoes could host metalliferous magmatic brines that could one day be tapped.

     The volcano at Montserrat erupted in the 1990s, devastating the island. As a result, its population was reduced from 12,000 to just 4,000 inhabitants as people left after the eruption destroyed the island’s biggest town. It has had a continuous eruption for 20 years but is now showing signs of dormancy. If it could be tapped for geothermal energy, it could power the island as well as produce metals. It could replace the diesel generators that currently power the island. The Montserrat research is expected to go on through October 2026.

 

 

References:

Scientists make energy breakthrough after observing geofluids in dormant volcanoes — here's what it could mean. Stephen Proctor. The Cool Down.  July 25, 2024.  Scientists make energy breakthrough after observing geofluids in dormant volcanoes — here's what it could mean (msn.com)

Geofluids: Developments in Microthermometry, Spectroscopy, Thermodynamics, and Stable Isotopes. A volume in Vapor-Liquid Equilibrium Data Bibliography. Book. 2015. Geofluids | ScienceDirect

UK scientists eye dormant volcano juice to extract battery metals, energy. Aleya Paleja. Interesting Engineering. July 1, 2024. Oxford eyes dormant volcano juice to extract battery metals, energy (interestingengineering.com)

Mining volcanoes for metals. Ingenia. March 2024. Mining volcanoes for metals | Ingenia

Mining the brine. Olivia Hogg and Jon D. Blundy. Geoscientist. May 16, 2022. Mining the brine - GEOSCIENTIST