Researcher develops technology to provide cleaner energy and cleaner water

Wencai Zhang, associate professor in the Department of Mining and Minerals Engineering, is leading this project to recover high-demand metals, such as lithium and rare earth elements, from produced water from the Marcellus Shale in the Appalachian Basin. Produced water is naturally occurring water that comes out of the ground during the production of natural gas and can contain pollutants such as lithium, along with sodium chloride, calcium, and magnesium that cause extremely high salinity levels. Researchers aim to reduce salinity levels and remove pollutants while extracting lithium for other manufacturing applications.

“High-demand metals and minerals, such as lithium, play an essential role in electric vehicle production and are present in virtually every battery worldwide,” said Zhang. “Our goal is to contribute to the supply chain of these critical materials while also making a positive environmental impact. We specifically aim to reduce the environmental consequences that can be associated with produced water.”

The novel approach

Although several studies have been performed on lithium recovery from produced water, a complete process that can produce battery-grade lithium has not yet been developed.

Enter Zhang and his team, who have developed a novel process for achieving beneficial uses of produced water, including valuable mineral recovery and carbon fixation. Their project involves five major phases to treat the produced water and harvest these high-demand minerals.

Phase one: Produced water treatment

Zhang and his team will begin by treating the produced water from the Marcellus Shale in the Appalachian Basin with the aim of removing any solid particles while maintaining minimal loss of valuable minerals.

Phase two: Rare earth elements and critical metals recovery

In order to recover these high-demand minerals, Zhang has developed patented and patent-pending technologies to recover critical minerals from the produced water. The concentration of the minerals in the produced water is too low for efficient recovery, so Zhang’s method, known as staged precipitation, concentrates critical elements from the solution so that they can be efficiently extracted and further refined.

Phase three: Direct lithium recovery

The conventional method of lithium extraction from the earth is costly and requires a significant amount of energy. The researchers will combine a specially designed ion-exchange system, which is used in the separation of substances and is specifically selective for lithium, and a multiple-stage solvent extraction process that has been significantly modified to suit produced water treatment. Zhang and his team’s novel method for direct lithium extraction is cost-effective and less energy-intensive. 

Phase four: Carbon mineralization

Produced water contains alkaline earth metals, such as calcium and magnesium, which contribute to the hardness of water, or how usable it is. Zhang and his team will be using carbon mineralization to remove these metals by adding carbon dioxide gas to a solution that contains alkaline earth metals, which then allows carbonate compounds, such as calcium carbonate, to form and settle out of the solution. By turning carbon dioxide and minerals into solid particles, they can then be filtered out of the water. 

Phase five: Phyto-microbial treatment

In the final project phase, Zhang and his team will be reducing salinity levels and removing pollutants from the produced water using phyto-microbial treatment, which involves employing plants and their respective microbes to clean up contaminants in the produced water. They will intentionally select certain plants with excellent purification characteristics that might not normally grow in the location of the produced water. These plants and microbes will be tailored to the removal of all contaminants, resulting in cleaner water.

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Taxonomy

• lithium