ABSTRACT
Metals are necessary for living organisms in order to maintain homeostasis, for example zinc in zinc finger protein and iron in hemoglobin. However, the same can also establish toxicity at the high dose, which is the unique character of each individual metal. The industrial processes require very high amounts of metal as raw materials to feed the production lines which resulted in a high load of metal waste generation. The trends of metal consumption in the industrial sector keep increasing every year according to the demand of raw materials. M. Tcha and G. Takashina reported that the consumption pattern of seven major metals, namely steel, aluminum, copper, lead, nickel, tin and zinc is in imbalance between demand and reserve. There are many techniques available to take the metals out from the solid phase. Hydrometallurgical methods are one of the common applications in this field. The chapter also presents an overview on the key concepts discussed in this book.
