Critical minerals locked away in produced water

Siobhan Doyle

Recent research reveals that a wealth of critical minerals is discarded along with water deemed too contaminated and costly to purify.

Dr Hamidreza Samouei, a research assistant professor of Petroleum Engineering at Texas A&M University, is investigating the components of produced water, stating that this waste byproduct of oil and gas operations contains nearly every element in the periodic table, including those of significant interest to national economies.

Samouei’s goal is to treat the water using unwanted carbon dioxide (CO2) in stages to recover these valuable elements and ultimately produce fresh water for agricultural use once the processes are complete.

“Recognising the latent value within produced water can offer tangible solutions to some of the world’s most pressing environmental challenges, from CO2 emissions to the increasing scarcity of certain minerals and water itself,” Samouei explains.

The hidden gems

Since everything in produced water has never been catalogued, Samouei collected produced water samples around the US and created a standardised method of analysing the water’s content. Here, he learned it contained nearly everything listed in the periodic table of elements.

Samouei’s research uncovered a variety of critical minerals such as lithium, rubidium, cesium, gallium, and platinum group metals. These substances are essential for advancing technologies in computer, energy, and transportation industries.

Additionally, the produced water, like other brines, contains plentiful and cost-effective quantities of sodium, potassium, magnesium, and calcium, crucial for various manufacturing processes and fertiliser production.

Samouei suggests that the value of the minerals extracted from produced water could outweigh the revenue from the oil content, making it feasible to cover water reclamation costs by selling these minerals.

A better treatment

Samouei outlined that while desalination of produced water has been a topic of consideration, the strategy of initially extracting all the salt and minerals before treating the water had not been investigated.

His ongoing research focuses on devising optimised methods for extracting valuable minerals from brine through staged refinement using CO2 desalination. He describes this as “a groundbreaking approach to targeted mineral recovery from produced water,” involving various filtration methods such as ultrafiltration, nanofiltration, and reverse osmosis.

The research is establishing a foundation for brine mining, whether from produced water or other brackish sources. However, Samouei emphasises that further progress would require funding. Currently, government sponsors prioritise critical mineral mining in distant locations such as the sea floor or asteroids, rather than focusing on resources as accessible as produced water.

Samouei expresses hope for a shift in the oil and gas industry’s perspective on produced water. Initially, he aims for recognition of its potential profitability and envisions its incorporation into mining operations within the next decade. “Produced water may not be beautiful if we look at it as a waste, but it will be impactful to the world’s next generations if we look at it as a resource.”

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