Efficient stabilization of barium- and gypsum-bearing tailings by one-step dry ball milling—An ingenious inspiration

Abstract

The stockpiling of massive amounts of easily leachable barium-containing slag poses an unpredictable risk to the environment and human health. Current researches into the treatment of barium ion (Ba2+) contamination are largely focused on end-of-pipe treatment, with few options for front-end sequestration. In this study, gypsum dihydrate was used to passivate barium carbonate (BaCO3) to form a hard-to-leach barium salt (BaSO4) directly by simple dry ball milling, successfully to prevent barium leaching from the landfilling. Phase identifications of the samples before and after ball milling were performed to confirm the production of BaSO4 and acidic leaching of the milled sample was performed to identify the Ba2+ passivation. Additionally, large amount of CaCO3 as the byproduct of forming BaSO4 may be used as a slow-release base for efficiently treating acidic wastewater containing heavy metals. This research may open up a new green process to treat both barium-containing and gypsum tailings, and eventually achieves the purpose of treating waste with waste.