image: (From left) Graduate student Peidong Liu and mining and minerals engineering Associate Professor Wencai Zhang analyze water samples in the lab.
Credit: Photo by Hailey Wade for Virginia Tech.
As the world transitions to cleaner energy sources, the need for energy-relevant metals and critical minerals has surged dramatically. Driven by the rise of electric vehicles and other green technologies, these essential materials are in high demand across the globe.
Metals, such as lithium, cannot be grown. They must be mined or recycled, making this a top priority for researchers in the mining industry. Traditional methods of mining lithium are expensive and can be harmful to the environment, but researchers at Virginia Tech have found a way to minimize this environment impact. They will optimize and scale up this method with a pending Department of Energy grant worth over $1.8 million, including $1.5 million in federal shares.
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.
Environmental improvements for the future
The minerals recovered from this project play a critical role in our modern society. With an electric vehicle future on the horizon, Zhang is teaming up with interdisciplinary researchers and industry partners that will contribute their expertise and relevant data for the project. Their partners include
- Colleen Doherty, associate professor of molecular and structural biochemistry at North Carolina State University, will lead phase five of the project.
- Austin Elements, a battery-recycling company, will lead the effort of phase three and the pre-pilot construction and techno-economics for the commercialization.
- EQT Corporation, a leading natural gas producer in the United States with operations in the Appalachian Basin, will provide the team with sufficient produced water for experimental tests.
When collaborating on a project with such significant impacts like cleaner energy and cleaner water, having a shared goal becomes crucial. The research team’s goal for this project happens to benefit our region.
“The Marcellus Shale is a significant geological formation known for its rich deposits of natural gas, particularly shale gas,” said Zhang. “It is located primarily in the Appalachian Basin in the eastern United States, which includes part of Virginia. This project offers the opportunity to unlock additional environmental benefits for this region.
“My knowledge itself cannot solve this issue, so it’s crucial to the project that we have collaborators who have industry relevant knowledge that will make a substantial impact on the project and get the issue resolved."
The potential future impact of this project is substantial, and integrating this research into common practice could significantly enhance the benefits of shale gas production. Shale gas companies operate multiple production sites, often relying on centralized water facilities to collect and distribute water across various locations. Zhang and his team’s technology can be integrated into these facilities to optimize this process.
Treated produced water could also be used as irrigation water in the future, supporting agriculture in the region.
“Our technology not only facilitates the recovery of valuable minerals like lithium, but also ensures that the water remains suitable for shale gas production," Zhang said. "We can also reduce water salinity, providing cleaner water to support agriculture in areas with low water supply."