The document discusses two methods for recovering valuable metals from e-waste: hydrometallurgy and pyrometallurgy. Hydrometallurgy uses aqueous chemistry and room temperature liquids to leach, concentrate, and purify metals like silver, copper, and zinc from e-waste. Pyrometallurgy applies high temperatures through processes like calcination, roasting, smelting, and refining to extract metals like iron, copper, zinc, chromium, and manganese. While pyrometallurgy has higher recovery efficiency and accelerated reaction rates, it is also more energy intensive, capital intensive, and produces toxins.