Cook, RD & Johnson, JL 2015, 'A novel method to locate and profile the bed of a thickener', in R Jewell & AB Fourie (eds), Paste 2015: Proceedings of the 18th International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 45-53, https://doi.org/10.36487/ACG_rep/1504_01_Cook (https://papers.acg.uwa.edu.au/p/1504_01_Cook/) Abstract: Measuring mud bed level in a sedimentation device is an important control variable. Current methods used for this purpose have had limited success providing continuous, consistent measurements at a reasonable price. This is especially true for high-density and deep-cone type thickeners which are becoming more prevalent in the mineral industry. Optimising underflow rheology is dependent on steady operation, which is linked to the ability to control bed level (solids residence time). This paper describes a new instrument for detecting the mud bed/liquor interface as well as the rheology of the mud bed. Measurements are made directly with sensors located in the thickener. Data from bench-scale and full-scale tests demonstrate this technology has the ability to provide insight into the dynamics of a thickener bed and the potential to revolutionise thickener control. The instrument, continuously and in real time, monitors bed level and rheology, detecting horizontal, vertical and radial variation. Thickener ailments like rat holes and island formation could be detected before they are fully formed, allowing corrective measures to be taken before experiencing costly shutdowns.