Upcycling — After the extraction, the remaining waste is less harmful to the environment. Enlarge / A red mud retaining pond in Germany. The metals that form the foundation of modern society also cause a number of problems. Separating the metals we want from other minerals is often energy-intensive and can leave behind large volumes of toxic waste. Getting them in a pure form can often require a second and considerable energy input, boosting the associated carbon emissions. A team of research...