MINING MILLING PROCESSES AND TAILINGS GENERATION

Economic abstraction of valuable minerals from a mineral deposit gener ally requires physical or mixed physical and chemical processing of th e mined ore to produce a mineral concentrate. Such concentrates then b ecome feedstock for pyro- or hydrometallurgical plants to produce fini shed metal ol mineral products to market throughout the world. These m iner al processes also produce tailings, or waste materials, which can consist of solids, ranging in particle size from cobbles to ultrafine clay of only 1-2 mu in diameter, plus usually an aqueous phase. The l atter phase derives from the fact that most processes are conducted in water. The tailings solid can vary from being essentially inert to ch emically unstable and subject to dissolution or weathering followed by dissolution. The aqueous phase can in turn be uncontaminated or conta in enough dissolved metals or residual milling chemicals to make the t ailings potentially toxic. Detailed knowledge of the mineralogy of an ore and the physical and chemical actions involved in mining and proce ssing are all essential in predetermining the possible suitability of tailings for submarine discharge. In addition, weathering tests and/or chemical leaching tests will generally be required to ensure that tai lings that might be discharged in a submarine environment will remain chemically noncontaminating. This paper describes some of the characte rizations of tailings materials that can indicate their possible suita bility or nonsuitability for submarine discharge.