ABSTRACT
Solution mining is variously defined. In this text it includes all forms of extraction of materials from the earth by leaching and fluid recovery, both by in situ methods and heap leaching of excavated ore. The emphasis is on minerals, brines and other naturally occurring solutions, but the theory and practice developed for these materials can be extended to contaminants introduced into the earth by human activity. Several minerals are readily soluble in water, forming brines, and recovery of these fluids represent the earliest applications of solution mining. Extraction of solid minerals by an aqueous solution flowing through and leaching (dissolving) them from their host rock has become of increasing importance in solution mining. This includes both readily soluble evaporite minerals and metallic ore minerals requiring leaching reactions with acids or other chemical lixi-viants and, often, oxidation of the mineral. In outlining the scope of solution mining in this introductory chapter, some words will be contextually defined as they are conventionally used in solution mining practice.
