Dewatered and Stacked Mine Tailings: A Review

• Published in: ACS ES&T engineering Vol. 2; no. 5; pp. 728 - 745
• Main Authors: Furnell, Erin, Bilaniuk, Ksenia, Goldbaum, Matthew, Shoaib, Mohammed, Wani, Omar, Tian, Xinyi, Chen, Zhirong, Boucher, Darryel, Bobicki, Erin Rae
• Format: Journal Article
• Language: English
• Published: American Chemical Society 13.05.2022
• Subjects: dry stack; unsaturated; mine waste; filtered tailings; stacked tailings
• ISSN: 2690-0645; 2690-0645
• DOI: 10.1021/acsestengg.1c00480

Tailings storage is a prescient issue in mining, representing a visible and destructive liability. Dewatering tailings to a paste-like consistency is a popular option to reduce tailings volumes and increase dam safety, but dewatering further to a bulk cake consistency has mostly been reserved for small operations in locations where seismicity or terrain prohibited the construction of dams. The recent high-profile failures of tailings dams such at Fundão and Brumadinho facilities along with the push toward socially conscious investing have generated renewed and urgent interest in tailings dewatering, including stacked (“filtered” or “dry-stack”) tailings. While geochemistry and civil engineering topics relating to tailings in general are both extensively studied, very little academic literature is available specifically on stacked tailings, with discussion mostly confined to conference articles or extrapolation about the behavior of dewatered tailings. Furthermore, the nomenclature around and definition of this method of tailings storage is inconsistent, which can make researching the topic unnecessarily tedious and confusing and, in the worst case, can open the door to intentional misrepresentation of a tailings storage facility’s safety as this is a technology still being scaled up. In this article, the term stacked tailings (ST) is introduced to describe what has been otherwise called filtered tailings or dry-stack­(ed) tailings to remedy the inaccuracies with the two existing names and gather the existing literature in one place. Topics covered include the existing definitions of dewatered and stacked tailings; opportunities and barriers to adoption; and construction and general operation for such tailings storage facilities. These are supplemented by an overview of literature in geotechnical and geochemical topics relevant to tailings dewatering (ex. clays) and tailings storage facilities. Emerging dewatering technologies and innovations which might be useful in the scaling up of the technology are also discussed. The aim is to provide a thorough background on the topic for a general audience, outline gaps in the literature, and encourage further exploration of stacked tailings and tailings cake by furnishing a comprehensive list of sources. Stacked tailings are discussed in a rigorous way to make the topic a more approachable way to encourage standardization and adoption, scale up, and the development of associated technologies.