Tailings dam failures, claiming human lives and causing catastrophic environmental impact, are unfortunately still frequently reported around the world.The tailings dam break simulation using site-specific parameters has now become an essential and critical part of the design, operation and closure cycle of every tailings storage facility (TSF), and is a requirement in many guidelines such as ANCOLD (2012), CDA (2021) and ICMM (2020). Urging from the mining industry and regulatory authorities for the development of better and more comprehensive simulating techniques that can accurately predict the flow behaviour of liquefied tailings in the hypothetical scenario of a tailings dam breach has significantly increased in recent years.The tailings deposited in a TSF often form a density profile with depth as the tailings consolidate and gain strength. This process increases the solids concentration and shear strength of the tailings within the TSF to a range that often makes direct measurement of the rheological properties of samples from the site using conventional bob and cup rotary viscometry impractical. Consequently, this imposes a challenge for obtaining reliable results from the tailings dam break simulation and needs to be overcome.A methodology is proposed in this paper for estimating the rheological properties of liquefied tailings at high solids concentrations when the direct measurement technique is impractical. The method is based on combining site-specific parameters such as the in situ dry density with laboratory-measured parameters such as the residual shear strength of the tailings after failure, and the bob and cup rotary viscometry data at lower solids concentrations.The method can be applied to establish a comprehensive understanding of the rheological behaviour of liquefied tailings at the wide range of solids concentrations required for dynamic tailings dam break modelling.

This paper presents the design aspects and challenges involved in upgrading an existing thickened tailings delivery and distribution infrastructure with the aim of utilising the system for a newly constructed tailings storage facility (TSF). The operation is Oyu Tolgoi, the largest copper and gold mine in the Inner Asia region with a total throughput of 40 Mtpa. The thickened tailings are currently discharged to the existing TSF cell at a solids concentration of 56 -64%. Similar to the existing TSF cell, a new cell is designed as a turkey-nest-type TSF which will be raised annually using the mine waste. The new TSF cell is about 2 km long by 2 km wide and the tailings will be distributed to the TSF from the western and northern walls via multiple manifolds and spigots using a specifically designed linear distribution system.The proposed upgrades to the tailings delivery pipeline and the modified linear distribution system will significantly improve the operation of the existing tailings pumps and optimise the tailings deposition into the new TSF. The proposed modifications also minimise the need for relocation of the excessively large tailings pipes during the operational life of the TSF.The proposed upgrades and alterations to the existing infrastructures are discussed and presented in this paper.