Carlberg, S, Courtenay, S & Katchen, J 2023, 'Selection and operation of Metso Outotec second generation paste thickener at the New Afton Mine', in GW Wilson, NA Beier, DC Sego, AB Fourie & D Reid (eds), Paste 2023: Proceedings of the 25th International Conference on Paste, Thickened and Filtered Tailings, University of Alberta, Edmonton, and Australian Centre for Geomechanics, Perth, pp. 372-385, https://doi.org/10.36487/ACG_repo/2355_28 (https://papers.acg.uwa.edu.au/p/2355_28_Katchen/) Abstract: The New Afton Mine has been in commercial operation since 2012 with the New Afton Tailings Storage Facility (NATSF) used as the primary tailings deposition site. In order to process future underground B3 and C-Zone ores and extend the lifespan of the current operation to 2030, new thickened and amended tailings (TAT) facilities were installed. For the TAT facility, a high yield stress and solids concentration material was required for the mill tailings stream to facilitate amendment with cement and deposition to the Historic Afton open pit (APTSF). A 45 m diameter Metso Outotec second generation paste thickener was selected to achieve the target slurry characteristics and was commissioned in early 2022. This paper discusses the drivers behind the selection of the TAT process for in-pit tailings deposition as well as the selection of the paste thickener. Early operating results and the process optimisation required to achieve the desired overflow and underflow targets are reviewed. Early operating performance is compared to the original design test work. Furthermore, the paper details the value of Metso Outotec second generation paste thickener technology in achieving operational targets for tailings deposition at the New Afton Mine. Keywords: thickener, paste, in-pit tailings disposal