Hydrometallurgy and Electrometallurgy

In Chapter 8 we examined some traditional techniques for the production of “tonnage” metals such as steel, aluminum, and copper. These techniques involved high temperature, molten metals, and slags and difficulties posed by the emission into the environment of particles, sulfur dioxide, and so on. In the present chapter we examine some alternative techniques that make use of aqueous chemistry to extract metals from ores and concentrates. This “hydrometallurgical” technology employs much lower temperatures than those encountered in Chapter 8. Nevertheless, hydrometallurgical techniques still entail the consumption of considerable quantities of energy, particularly when the energy costs associated with producing reagents are considered. However, hydrometallurgical processes typically pose no air pollution difficulties, but steps must usually be taken to avoid water pollution.