Sustainable Management of Thickened Tailings in Chile and Peru: A Review of Practical Experience and Socio-Environmental Acceptance

Abstract

The “Thickened Tailings Disposal” (TTD) technology produces a high density mine waste that allows for the storage of this material without the need to manage large slurry tailings storage facilities (TSFs) and large dams. TTD has been applied considering site specific conditions of Chile and Peru, such as extreme climatic conditions, seismic risks, water scarcity, community demands, and environmental constraints. This review highlights the contribution of several experiences in Chile and Peru, which have chosen TTD technology for reduction of negative environmental impacts, mainly focusing on the following issues: (i) increase of tailings water recovery, (ii) reduction of TSFs footprint (impacted areas), (iii) decrease the risk of physical instability, avoiding the construction of high dams, and (iv) decrease of TSFs seepages. Finally, the article describes the advantages (benefits) and disadvantages (aspects to improve) of TTD, where nowadays a high degree of dewatering of tailings is seen as a safe option, considering the occurrence of some TSF dam failures recently worldwide, which has resulted in severe environmental pollution. A better environmental perception about TTD of authorities and communities, considering that this technology allows to satisfy the needs of stable and safe TSFs, make the TTD be more acceptable, popular and one of the best available technologies (BATs) for operations with mine tailings.

Past, Present, and Future of Copper Mine Tailings Governance in Chile (1905–2022): A Review in One of the Leading Mining Countries in the World

“…Dust emission controls will play an important role as good design and proper implementation will provide the primary control mechanism for dust in accordance with regulatory air quality requirements. Some dust control alternatives to implement are: soil cover (borrow material), top soil/re vegetation cover, phytostabilization, and binder material or chemical agglomeration [ 53 ].…”

“…These channels are formed by ditches of trapezoidal section lined, such as concrete cloth, geoweb, or precast concrete, with average slopes of 0.5%, and using corrugated steel pipelines in lengths with slopes over 10%. Both channels collect coming from surface water runoffs, restricting their entrance to the tailings impoundment, and discharging these flows downstream of the TSF [ 53 ].…”

“…In this way, TTD achieves high water recovery (70% of recovered tailings water content) and self-supporting tailings storage facilities with sloping beach surfaces, requiring small dams ( Figure 20 and Figure 21 ). Some mining operations that use this technology are: Centinela, Sierra Gorda, Spence, Carmen de Andacollo, and Chuquicamata–Ministro Hales–Radomiro Tomic (this last case is in the feasibility phase of implementation in Talabre tailings storage facility) [ 8 , 53 ].…”

“…The main advantage of this method is that large dams are not required; only small dams are needed and the stored tailings material forms a solid crust with steep deposition slopes of the order of 2.0% to 4.0% ( Figure 22 and Figure 23 ). Some mining operations that use this technology are: El Toqui, Enami Delta Plant, Las Cenizas, Demo Plant Collahuasi, and Alhue [ 8 , 53 ].…”

Socio-Environmental Risks Linked with Mine Tailings Chemical Composition: Promoting Responsible and Safe Mine Tailings Management Considering Copper and Gold Mining Experiences from Chile and Peru

“…In practice, there are different definitions for mine tailings from different points of view considering the experience of different professional disciplines involved in mine tailings management [ 2 ]. Thus, for example, from a metallurgical point of view and considering the process, mining tailings are defined as the remaining low-grade material of valuable beneficiation metal, that is, the gangue obtained through the flotation process [ 11 ]. Another discipline that intervenes in the issues of tailings transport from the concentration plant to the tailings deposit is the hydraulic area, where tailings are defined as a solid–liquid mixture, whether a slurry, paste, or solid in bulk, with a concentration of solids determined by weight (Cw) associated with a viscous hydraulic behavior with rheology of the Newtonian or non-Newtonian type [ 12 ].…”