Tailings (also known as slimes, tailings pile, tails, leach residue, or slickens) are the materials left over after the process of separating the valuable fraction from the worthless fraction (gangue) of an ore. The extraction of minerals from ore requires that the ore be ground into fine particles, so tailings are typically small and range from the size of a grain of sand to a few microns. Mine tailings are usually produced from the mill (grinding) in slurry form (a mixture of fine mineral par… (More on Tailings)