Rare earth elements are used in a wide variety of modern technologies, from wind turbines to phones. "The results show that alkaline pretreatment of coal tailings prior to acid digestion significantly influences REE extraction efficiency, with minimal extraction in the alkaline solution," write the researchers in their published paper. The extraction process may present a real improvement in terms of efficiency, but it remains expensive and might be difficult to scale up. The extraction process would need to be refined in each case. "This approach provides new insights into the mechanisms of REE release and the potential for optimizing alkali pretreatment of coal waste for efficient REE extraction," write the researchers.