Tailings are a sand-like byproduct of mining activities which are the result of crushing ores before mineral extraction. Often, tailings are disposed of in dams built using more tailings, or other waste products. While technical knowledge exists to safely build these structures, failures of dams, with tragic consequences, are occurring at an unacceptably high rate.
There have been significantly destructive tailings dam collapses in countries such as South Africa, Japan, Italy, Canada—and, most recently, Brazil. In January 2019, a tailings dam at the Córrego do Feijão iron mine in the small Southeast town of Brumadinho, collapsed.