Yuan, XS, Wang, N, Dunmola, A, Curran, M, Sharp, J & Lanoue, A 2023, 'Co-processing of fresh oil sand tailings and fluid fine tailings', 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. 495-509, https://doi.org/10.36487/ACG_repo/2355_37 (https://papers.acg.uwa.edu.au/p/2355_37_Yuan/) Abstract: This paper describes co-processing of fresh tailings (i.e. whole tailings), such as coarse tailings and flotation tailings from the oil sand extraction plant, and legacy fluid fine tailings (FFT) in line with a polymeric flocculant to produce paste tailings without the use of thickeners and cyclones. The objective of the project is to develop an efficient and low-cost tailings management technology to accelerate the creation of trafficable landforms that are ready for terrestrial reclamation. The idea for co-processing is that increasing the sand-to-fines ratio (SFR) will increase the hydraulic conductivity of the co-processed deposit, thus accelerating its consolidation rate. Compared to composite tailings (CT) with SFR of 3–5 and FFT centrifuge cake or flocculated FFT (fFFT) with SFR of 0–0.1, the target SFR of co-processing is 1–3 with an optimal SFR of 2. In a broader definition, the co-processing could become the treatment of whole tailings when the FFT supply is shut down or switch to the flocculated FFT process if the fresh tailings are diverted for conventional beaching operation. This paper highlights the advancements in co-processing technology development from laboratory-scale to small pilotscale. It discusses learnings from large strain consolidation (LSC) and beam centrifuge testing of the co-processed deposits to assess its long-term consolidation within the context of final reclamation and closure. Results to date show that co-processing of fresh tailings and FFT is a promising technology for achieving terrestrial closure of oil sand tailings. Keywords: co-processing, fresh tailings, FFT, whole tailings, paste tailings, flocculant, SFR, hydraulic conductivity, LSC, beam centrifuge, terrestrial, trafficable landform, reclamation