taillings

Tailings, sometimes misspelled as taillings, are the materials that remain after the processing of ore to extract valuable minerals. They are usually a slurry of finely ground rock and process water, and they may contain residual processing chemicals, metals, and sulfides. The exact composition varies with the ore, the beneficiation method, and whether flotation, grinding, or leaching were used.

Most tailings are transported to a storage facility, where they are disposed of as tailings in a tailings storage facility (TSF). Depending on the design, these facilities store tailings in an impounded pond behind a dam, or in dry or thickened form through filtration and stacking. Water is often recycled back into the processing plant.

Tailings facilities pose long-term containment and environmental risks, including seepage into groundwater, surface water contamination, dust if dried, and the potential for dam failure, which has caused catastrophic spills in past incidents. For this reason, the design, operation, monitoring, and closure of TSFs are subject to regulatory oversight and international guidance. In recent decades, improvements in engineering, independent risk assessments, and early warning systems have been implemented to reduce risk.

Handling and recovery: Some tailings can be dewatered or dry-stacked to reduce water content; tailings may also be reprocessed to recover residual minerals. During processing, tailings may contain cyanide or other reagents, necessitating treatment and safe management of residues. Closure and rehabilitation plans seek to stabilize and reclaim tailings sites, often by encapsulation, capping, water treatment, and ecological restoration; some sites are repurposed for other uses or as landforms after stabilization.