Barrera, S & Engels, J 2018, 'High-density thickening for large production rates: main challenges', in RJ Jewell & AB Fourie (eds), Paste 2018: Proceedings of the 21st International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 35-42, https://doi.org/10.36487/ACG_rep/1805_02_Barrera (https://papers.acg.uwa.edu.au/p/1805_02_Barrera/) Abstract: It has been apparent for some time that for large production rates where high-density thickened tailings disposal is considered (e.g. Minera Centinela and Toromocho), significant challenges have been observed to reach the design underflow solids concentration. Many possible explanations have been proposed and at the 19th International Seminar on Paste and Thickened Tailings a panel discussion was held addressing this problem in detail. Usually the issue is a combination of operational parameters resulting in variable performance of an industrial thickener. The purpose of this paper is to review and discuss the views raised in the panel discussion as indicated above, as well as visions/experiences on control and operational management of tailings thickeners for recent cases. Keywords: thickening, thickener, operational control, panel discussion