PFI:AIR - TT: Hydroacoustic Cavitation for Reclaiming Clay and Sand from Hydrofracturing Fluids and Solids

This PFI: AIR Technology Translation project will apply a novel sand-clay separation technology to processing hydrofracturing waste solid slurries, drilling muds, and fluids. This will allow the clays to be reused in drilling mud and other clay applications, and the sand to be reused as proppant, rather than being discarded as solid wastes. This project will help promote American energy independence, national security, and economic competitiveness, because it solves two issues in the natural gas industry - namely how to reclaim solids that are conventionally landfilled, and how to manage radium.

More broadly, the solids reclamation and radium management strategies developed here could also be used at other natural gas and petroleum-extraction operations in PA, TX, WY, CO, WV, and LA. The reuse of the solids will reduce traffic near hydrofracturing and decrease the volumes of waste hauled to landfills and the volumes of new material that is mined. The project will result in a pilot scale application of hydroacoustic cavitation-advanced oxidation (HAC-AO) for treatment of hydrofracturing waste solids. Importantly, HAC-AO offers the ability to treat solids in the presence of radium and hypersaline brines, when salt levels are 4-10 times higher than ocean water. This feature provides an advantage when compared to other technologies in this market space. When these solids can be reclaimed and reused, operations costs will be significantly diminished. For example, when HAC-AO was applied to a mixed hydrofracturing solid waste slurry, about 15-20% of the solids could be reclaimed as high-quality clay, and 35-45% reclaimed as good sand proppant. That left only 35-40% remaining to be wasted. When considering clay and sand purchasing costs, and solids landfilling fees, this reclamation represented several hundred dollars per ton for the reclaimed material that would conventionally be wasted.

This project addresses the following technology gaps as it translates from research discovery toward commercial application. Specifically, clay-cation-radium interactions in the presence of hypersaline brines and cation-clay association kinetics, after the HAC-AO has exposed and activated fouled clay surfaces. Radium activities in hydrofracturing brines are often thousands of pCi/L range. Prior results show that the clays, when activated by HAC-AO, increase their capacity to capture radium. Importantly, this means that the other solids and liquids, when wasted, will conversely host less radium, making it unnecessary to truck them to radioactive waste sites; if more stringent regulations arise-as may happen. An HAC-AO system can reclaim both clay and silica sand proppant from hydrofracturing solid waste slurries and fluids. When the Penn State team processed hydrofracturing waste brines in these prior studies, nearly all of the otherwise wasted clay could be reclaimed.

During this project, graduate students will receive entrepreneurship experiences through interaction with the industrial partner, Hydro Recovery, LP. The project engages Hydro Recovery LP to both provide the waste materials and guide commercialization within the rapidly changing hydrofracturing industry. These two items are vital in this technology translation effort from research discovery toward commercial reality and graduate students will benefit from working closely with Hydro Recovery during the process.