Optimised Seasonal Deposition for successful management of treated mature fine tailings

Transcription

1 Paste 2014 D. Van Zyl, R.J. Jewell and A.B. Fourie (eds) 2014 InfoMine Inc., Canada, ISBN Optimised Seasonal Deposition for successful management of treated mature fine tailings J. Caldwell Robertson GeoConsultants, Vancouver, Canada A. Revington Suncor Energy Inc. Calgary, Canada G. McPhail SLR, Australia L. Charlebois Robertson GeoConsultants, Vancouver, Canada Abstract Optimised Seasonal Deposition (OSD) is described and evaluated as a paradigm for the successful deposition and management of oil sands treated/flocculated mature fine tailings (MFT) near Fort McMurray, Alberta. Such treatment and management of oil sands is undertaken in order to meet or exceed the requirements of the Alberta Energy Regulator (AER) Directive 74, which calls for an undrained shear strength of 5 kpa one year after deposition, and 10 kpa five years after deposition, to facilitate reclamation. OSD involves placement of polymer-flocculated MFT as follows: Spring deposition of MFT to a depth that consolidation by subsequent lifts induces consolidation and strength gain. Summer deposition of MFT in thin lifts which dewater and gain strength by way of evaporative drying. Fall deposition of MFT to a thickness where freezing and thawing induces a gain in strength. This paper describes and evaluates the concept of OSD by way of a review and critique of technical papers presented by others working in the oil sands tailings industry. Introduction This paper introduces the concept of Optimised Seasonal Deposition (OSD) as a paradigm for the deposition of flocculated mature fine tailings (MFT) into dedicated disposal areas (DDAs) as mandated by Directive 74, a regulation issued by the Alberta Energy Regulators in order to promote that deposition of higher strength oil sands tailings. Significant work is in progress in the Alberta oil sands tailings management industry to find new and cost-effective ways to comply with Directive 74. Placement of treated MFT in thin lifts is but one of many approaches being evaluated, tried out in the field, and written about. The thesis of this paper is that, according to our understanding of the physical and financial requirements of such an operation, thin-lift drying alone will never be a stand-alone approach suitable for the dewatering of significant quantities of flocculated MFT, but that the management practice may be significantly improved by exploiting additional natural dewatering mechanisms together with improved facility design. Flocculated tailings do not readily flow from spigots in thin, uniform lifts to form sheets over large areas as idealized in the thin-lift concept; this fact significantly reduces the Paste 2014, Vancouver, Canada 1

2 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois reliability of thin-lift drying at a commercial scale. Additionally, the period of warm, dry weather available for drying is simply too short in northern Alberta, even if thin lifts could be consistently realized. This paper accordingly describes OSD, which includes the strategies of thin-lift drying (recognizing its fallibilities), consolidation, and freeze-thaw as a means to increase the quantity of treated MFT that may be placed in a dedicated disposal area (DDA) of limited and fixed area. The theory of thin-lift drying Song and O Kane (2013) present the results of their water balance calculations demonstrating the variable drying potential throughout the year in the Fort McMurray area and illustrate the fact that the highest drying potential exists in May through August. It may be inferred that strength gain during the remainder of the year must be achieved through other mechanisms. According to the OSD paradigm, flocculated MFT deposited in early spring will likely undergo little evaporation-induced drying or strength gain, but may benefit from consolidation-induced loading by subsequent summer and fall deposited layers. There is also a significant overnight freeze-thaw effect in the spring that should not be discounted. Flocculated MFT deposited in summer will undergo significant evaporation-induced drying and strength gain. Flocculated MFT deposited in fall will undergo winterrelated freeze and thaw-induced dewatering and strength gain come the subsequent spring. As the relative importance of each dewatering mechanism changes throughout the season, so too will the strength profiles developed in the deposit. The authors have considerable knowledge of MFT behaviour as a result of years of work on the Suncor Tailings Reduction Operations (TRO). Their experience forms the basis of this paper; however, none of the results of TRO work is presented in this paper, which focuses only on published papers by other industry representatives working in the field of MFT flocculation, deposition, and management. Current practice An overview of the practice of polymer amendment of MFT and thin-lift drying technology, and the regulations spurring its development, is provided by Sobkowicz (2013). He describes the process thus: The most recent commercially implemented technology is in line flocculation of mature fine tails with thin lift dewatering. Mature fine tails with a nominal solids content of 30% and a sand to fines ratio of 0.1 are recovered from tailings ponds, injected with a polyacrylamide polymer, and discharged on shallow beaches in thin lifts (100 to 300 mm) in dedicated disposal areas. After initial water release (within about 24 hours) solids contents increase to 50% or so. Additional dewatering occurs by drying. In some cases, the material is spread further in the cell by mechanical means and/or worked mechanically to promote drying. End targets for drying are in the range of 65 to 70% solids content, reaching peak undrained strengths of 5 to 20 kpa and remoulded undrained strengths of 1 to 5 kpa. The material is then either windrowed or removed to make room for the next lift, and eventually trucked to waste dumps. No multi lift deposits have yet been formed due to the long time required to reach higher strengths, but these are under consideration for the future. 2 Paste 2014, Vancouver, Canada

3 Oil Sands Optimised Seasonal Deposition (OSD) OSD makes use of natural forces to enhance deposition and strength gain of the deposited tailings. The idea is to use three natural mechanisms to assist in strengthening the tailings for reclamation. Our suggestions for how they could be applied are summarised below and shown in Figures 1 to 4. Gravity: in the spring, place a lift of tailings that will subsequently be covered by additional lifts, that in turn will load the first lift, induce consolidation, and hence induce strength gain. Over the medium to long term, (months, years, and decades) gravity drainage from the deposit may be expected (the management of such drainage should be considered). Evaporation: in the summer, place one or more lifts that are allowed to dry by sun and wind-induced evaporation. The number of lifts and the actual thickness is a function of the effectiveness of the flocculation process, the tailings discharge system, the containment cell design, and the actual evaporation rate from the solids matrix something that varies greatly with wind, sun, and temperature fluctuations over a typical Fort McMurray summer. Freezing: in the fall, place a third lift that is allowed to freeze in the winter and thaw the following spring. If there is adequate drainage, this upper layer may be stronger because of freeze-thaw-induced consolidation. The idea of OSD is tentative and not proven in practice. We offer it here simply to demonstrate that there are many problems in tailings deposition yet to be solved. In what follows, we examine recently published papers that talk of one or more of the approaches that would be involved in field-scale application of OSD. Paste 2014, Vancouver, Canada 3

4 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois Figure 1 Spring Deposition 4 Paste 2014, Vancouver, Canada

5 Oil Sands Figure 2 Summer Deposition Paste 2014, Vancouver, Canada 5

6 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois Figure 3 Fall Deposition 6 Paste 2014, Vancouver, Canada

7 Oil Sands Consolidation Figure 4 Summary of OSD Deposited tailings consolidate under their own weight, and as a result of the weight of subsequentlyplaced tailings. If the tailings are placed on a sandy base, the rate of consolidation is increased by basal drainage. Polymer amendment of tailings appears to significantly increase the permeability of the tailings. Thus the rate of consolidation of polymer-amended tailings is higher than the rate of consolidation for untreated tailings. This conclusion is based on personal observations by the authors, as the result of significant freeze-thaw monitoring and test pitting through multi-year deposits. Testing of field samples is ongoing at the time of writing this paper. No publications could be found on this topic and we encourage the industry to undertake research and publish on this topic. Hence, when implementing the OSD approach, it is feasible that about one to one and a half metres of tailings placed in the early spring when sun-induced drying is not effective, could be allowed to consolidate under self-weight and the load of the subsequent layers placed (as described below) during the ensuing summer, fall, and subsequent years. This opinion is based on the authors personal field experience and observations. Again the industry is encouraged to undertake research and publication on this topic as no data were available at the time of writing this paper. Obviously only the first lift of a thick, multi-season and multi-year deposit can be conveniently placed on a sandy base. In theory, a layer of sand could be placed over the fall lift prior to thaw in the spring. This Paste 2014, Vancouver, Canada 7

8 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois sand layer would then function as a permeable basal layer for the tailings deposited in the spring. Geodrains, sheet drains, or horizontal wick drains could be placed in lieu of sand. Not all authors agree on the role of consolidation, particularly as regards self-weight consolidation although for the most part consolidation induced by additional overburden loads is ignored. For example, as noted by Gidley and Jeeravipoolvarn (2014): It is found that i) evaporation is the main drying mechanism, ii) consolidation is inconsequential due to low self-weight stress and unfavourable material behaviours and iii) a certain lift thickness is required to optimise performance. Work is, however, being done to model the many complex mechanisms that control the permeability and consolidation of treated MFT. For example, Fredlund et al. (2014) write: The paper is focused on one particular study using a single material property and a single average climate scenario to determine the potential differences between a standard largestrain consolidation numerical model and a numerical model considering the effects of i) large-strain consolidation, ii) unsaturated flow, and iii) actual evaporation (AE). Although not directly comparable to polymer flocculation of MFT, Moffett et al. (2014) assert that the formation of a synthetic soil structure is central to inducing self-weight consolidation in a modified MFT: It has been estimated to take centuries for the fine tailings in these ponds to reach the consistency of soft clay. Untreated MFT in 10 metre columns at the University of Alberta showed minimal settling and consolidation over a 30-year period. Treatment of MFT by in situ polymerisation of silica creates a synthetic soil structure within the water phase of the tailings. Early data indicates silica treated MFT is demonstrating self-weight consolidation in a 10-metre column test. Thin lift drying During the summer months, thin lifts of polymer-flocculated tailings may be placed. The hot, dry conditions and the wind facilitate drying of the tailings. Evaporation from the surface of the tailings is the primary water loss mechanism at work (Yan et al., 2012). There is no agreement in the industry as to what constitutes a thin lift. Logically, it is a layer no thicker than can be dried to 5 kpa strength in a reasonable period. In our opinion, a lift no thicker (on average) than about 200 to 300 mm, will, in good summer weather, dry out in a short enough period to enable a series of thin lifts to be placed during the limited, short summer to create a summer layer about one metre thick in total. This thickness refers to the equivalent out-of-pipe volume per square metre of drying area, not accounting for initial water release on the beach which results in a higher density, thinner lift. Between 2003 and 2007, Suncor used lime-gypsum amendment of MFT (Wells and Riley, 2007) which gave a maximum lift thickness of 10 cm. This target thickness enabled drying at a rate where actual evaporation from the tailing was found to equal the potential evaporation rate; any lift thickness over this point resulted in an exponential decrease in evaporation. Similar evaporative rates were seen for a 50 to 100 mm lift by Moffett (2010) using the Particlear additive. Wells et al. (2011) indicated that use of polyacrylamide flocculants allowed for higher lift thicknesses ( mm) to be placed due to the release of 85% of the water by drainage. As noted by Zhang et al. (2014): 8 Paste 2014, Vancouver, Canada

9 Oil Sands In the MFT drying process, water release from the flocculation process occurs within a few days post deposition and can achieve an MFT solids concentration ranging from wt% solids. Additional dewatering, required to form a geotechnically stable deposit, is realized through evaporation and may take an additional one to three weeks dependent on the season and lift height thickness of the flocculated MFT. As the surface of the thin lift dries, it cracks (Figure 5). A well-flocculated MFT will crack soon after deposition, and the cracking will be extensive. Drying of the upper surface of the tailings inhibits drying of the deeper tailings below the rapidly developing partially saturated zone (the crust). However, the crack network may promote additional drying of the deeper tailings of the thin lift. The exact contribution to water loss as a result of cracking has yet to be quantified for flocculated MFT. Figure 5 Cracked treated MFT As noted by Innocent-Bernard et al. (2013), Surface cracking facilitates drying through the exposure of wet underlying material with lower suction and provides a new path for water to evaporate from the tailings. Left long enough, even a 500 to 750 mm thick layer of treated MFT will crack all the way through. It is readily observed that the tailings of subsequent lifts deposited onto the previous, cracked surface, will flow into the cracks. Some rewetting of the previously-deposited tailings occurs. The newlydeposited tailings in the cracks of the previous lift will in turn dry and shrink. The result is a layer of tailings the macro-permeability of which is probably higher than that of the non-cracked zones of tailings. The authors have observed this condition on many South African slimes dams. Thus when implementing the OSD approach, if should be feasible to place about one to one and a half metres of tailings during the summer, in a series of thin lifts that dry, crack, and generally result in a relatively permeable zone. Freeze and thaw Freezing and subsequent thawing of tailings may change the properties of the tailings through water migration, the formation of peds and lenses, and thaw strain. If provision is made to drain away the thaw water, the tailings may undergo an overall decrease of moisture content and an increase of strength as a result of the freeze-thaw process. The authors have observed that the freeze-thaw process results in prolonged periods of surface bleeding during thaw, facilitating evaporation at the deposit surface. The freezing depth of flocculated MFT under natural snowpack in the Fort McMurray area is slightly greater than one metre. Beier et al. (2009) provide a detailed description of the freeze-thaw process as it occurs in oil sands tailings. They review many papers about freeze-thaw effects on oil sands tailings and conclude that a Paste 2014, Vancouver, Canada 9

10 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois significant decrease of moisture content can result from freezing and thawing. Kabwe et al. (2013) describe consolidation testing of flocculated fine fluid tailings from Syncrude. With regard to testing of frozen tailings, they note: The frozen core samples indicated an increase of more than 40% in solids content over a period of five months including the winter period. Clearly, the higher the permeability of the tailings, the greater the moisture content reduction and increase in strength. It has been observed that polymer-flocculated MFT has a higher permeability than untreated MFT. Accordingly, it is logical that the decrease in moisture content and the increase in strength of freeze-thawed flocculated MFT will be greater than for untreated MFT. Provided, that is, that provision is made to drain away the thaw-released water in a timely fashion. Hence, when implementing the OSD method, it may be feasible to place in the late fall, up to one metre of tailings without regard for thin lifts or evaporative drying. If this fall-placed layer is left to freeze and thaw through the winter and early subsequent spring, it is feasible the result will be a 5 kpa or stronger material over which deposition may continue. The authors believe that provided there is drainage for the thaw-water, strengths of 8 to 12 kpa are feasible. Tests are underway as we write to confirm this opinion. Again this is a vast topic for research and publication by the industry. Criticism of OSD In reality, a deposit yielding 1.1 dry tonnes/m 2 /yr (in a way that the resulting material achieves a strength of at least 10 kpa to 30 kpa) would be desirable, and calculations by the authors suggest that this is reasonably achievable given the current state of practice (with overall improvements in consistency and reliability). However, if the deposit yield could be increased to about 2 to 3 t/m 2 /yr, significant capital cost decreases and acceptable operating costs may be realized. The authors recognize that there are many other approaches, besides OSD, of managing flocculated tailings. However, none of these has as yet proven more effective than we believe an OSD system could prove. Moreover, we must pause to reflect that many in the industry believe that discharging nonflocculated MFT into diked facilities closed with a floating cover and dewatering wick drains is a safer, easier, more cost effective way to manage oil sands tailings. As with all aspects of thin-lift drying: the bigger the area, the less MFT that needs to be placed per unit area, and the greater the flexibility in achieving dryable thin lifts, maximum consolidation, and winter freeze-thaw-induced strength gain. As discussed in a later section of this paper, a practical cell design and procedures for its operation remain to be formulated. It simply is not enough to continue small-scale cells and intense oversight by highly trained personnel. There are many other ways besides OSD of managing treated tailings. None of these has as yet proven more effective than we believe an OSD system could be. Yet we must pause to reflect that many in the industry believe that simply discharging untreated tailings into diked facilities that are closed by placing a floating cover and subsequently wick drains is a safer, easier, much more cost effective way to manage oil sands tailings. It is only a societal desire for speed and immediate solutions that make OSD and any of the other current oil sand tailings management options appear to be more effective than the use of gravity and time to close a facility. 10 Paste 2014, Vancouver, Canada

11 Oil Sands Cell design and construction Many different drying cell or DDA layouts have been proposed and constructed at the oil sands mines. The great challenge remains: the design of a large, permanent DDA that rises high and stable to form a new landform that may be de-licensed as it will respond in the long term to the forces of nature as with the surrounding landscape (Kupper et al., 2013). As noted by Gidley and Jeeravipoolvarn (2014): The ultimate end goal of tailing structures in the oil sands industry is to create an area suitable for closure and reclamation. The short-term goal for a tailings structure is to manage and store the fluid volumes required by the mine plan in a state that meets regulations. Within the life of the structure the strength of the tailings must evolve from its state at deposition to a point where the area can be safely accessed by heavy equipment to facilitate reclamation. In short: how do you operate a DDA that can ultimately backfill a large worked-out open pit? The following are some factors that enter into the design of such a system: Current cells for treated MFT have perimeter berms. Generally, the depth of material at the spigot is constrained by the height of the supporting header berm. A down-gradient (toe) berm acts to constrain beach length and provide for filling of individual cells with fixed beach lengths. Where two cells abut, and share a common header or toe berm, the rising height of the cells along one deposition front may act to buttress the adjacent cells indefinitely without causing instability, provided that flow-through and seepage to the down-gradient deposit is not significant. Where there is no toe berm and no abutting cell, the beach tends to flatten out to near-zero slope inclination. Thus in a long cell, it is possible that this very flat downslope inclination will play a significant part in promoting overall slope stability. A natural beach profile that develops by hydraulic placement forms essentially as the result of natural failure upon deposition; hence, the overall stability of a naturally deposited slope should not pose a significant risk to operations. However, when many multiple lifts are superimposed at significant rates of rise to greater heights, there is potential for excess pore pressure generation and instability. In such situations, the average inclination of the deposit and distribution of mass along the length of the deposit (determined by the profile) will be important considerations in assessing stability. The technical term, rate of rise, as used in the field of tailings management, refers to the rate at which tailings are deposited and hence the rate at which the elevation of the top of the tailings deposit increases. The rate of rise is a significant parameter controlling the rate of strength gain of a tailings deposit. The lower the rate of rise, i.e., the slower the tailings elevation increases, the more time there is for consolidation to occur as a result of the increasing stress resulting from ongoing tailings deposition. Hence, excess pore pressures resulting from placement of a lift may dissipate, the tailings may consolidate, and the tailings increase in strength. Tailings stacks deposited at low rates of rise are far less susceptible to slope deformation and failure than stacks constructed at high rates of rise. The ideal rate of rise is that at which excess pore pressures induced in low lifts, have just enough time to fully dissipate before placement of another lift. In the case of OSD, the rate of rise should also take into Paste 2014, Vancouver, Canada 11

12 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois account the expected rate of water removal by evaporation and the decrease in evaporative efficiency over time. As the tailings deposit rises with time, berm construction or berm raises are inevitable in most instances. Berms are expensive and difficult to construct, particularly if the material used in their construction has to be imported generally, material stripped from the mine workings is used. Jacking header systems are used at mines around the world to overcome this. An alternative to berm raises or jacking headers systems is to use the dried tailings product for berm construction. The authors have observed that dried treated MFT is suitable for berm construction. The issue remains how to dry sufficient quantities of treated MFT close to where it is needed for berm raising. Munro and Smirk (2013) describe mud farming as a way to expedite drying of fine tailings. They conclude that mud farming is practical once the tailings strength is greater than about 15 kpa. Note that in spite of the ideas underlying Directive 74, it is not possible to drive standard construction equipment over tailings of a peak undrained shear strength of 10 kpa as the remoulded strength of this highly sensitive material is significantly lower (Reid et al., 2014) the source from which the 10 kpa requirement in Directive 74 was adopted appears to have confused bearing capacity and trafficability. If a deposit of treated MFT having a strength which exceeds 15 kpa is windrowed, i.e., pushed up into a pile, the material of the pile is generally of a cloddy nature. The high permeability of this clod pile then increases the ventilation of the pile thereby facilitating drying. Precipitation on the windrowed pile rapidly flows down through the pile and does not significantly rewet the clods. Hence if a significant quantity of treated MFT can be produced to a strength of 15 kpa and then mud farmed and/or windrowed, it is feasible that sufficient quantities of construction material can be generated to raise perimeter berms using conventional tailings techniques. Li (2014) provides more detail on mud farming: In Australia, Rio Tinto Alcan produces alumina and has associated bauxite residue disposal facilities at Gove, and Gladstone (QAL and Yarwun), Queensland. At Gove, the bauxite residue is un-neutralised and disposed of as paste. At QAL and Yarwun, the residue is neutralised with sea water and thickened before discharge into disposal areas. In all of the residue disposal facilities, mud farming has been applied to increase deposited density and strength through the promotion of water drainage, consolidation and desiccation. Case History We believe we have established the validity of OSD at System 1, Cell 6 of at the Suncor site (Figure 6). The material deposited in 2010 was farmed, i.e., turned over and ploughed. The material deposited in the three subsequent years was not disturbed. The base of the cell is a relatively permeable sand. Significant strength is measured in the deposit (Figure 7). The bulk density indicates that on average about 0.8 tons per meter square per year of material was deposited into the cell (Figure 8). The current strength profile (Figure 9) establishes that the strength is much greater than required by Directive 74. In short TRO works. 12 Paste 2014, Vancouver, Canada

13 Oil Sands Figure 6 The triangular cell at the center of the photos show System 1, Cell 6 for which test data are provided in the following figures. Paste 2014, Vancouver, Canada 13

14 Depth Below Tailings Surface, 2013-Sept-15 (m) OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois Undrained Shear Strength (kpa) : 2* Lifts 2012: 3 Lifts 2011: 2 Lifts 2010: 8 Lifts * Lift 3 did not cover test location Cell Foundation 2012-May June Sept Nov-29 Figure 7 Strength gain in multiyear deposits at Cell Paste 2014, Vancouver, Canada

15 Depth Below Tailings Surface (m) Oil Sands Bulk Density (g/cm³) Figure 8 Bulk in situ density at Cell 6 Paste 2014, Vancouver, Canada 15

16 Depth Below Tailings Surface (m) OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois Undrained Shear Strength (kpa) Figure 9 Shear strength at Cell 6 16 Paste 2014, Vancouver, Canada

17 Oil Sands Conclusions Figure 10. A cut into polymer amended MFT that was deposited over one year. Treating MFT with polymer flocculants changes the short-term and long-term behaviour of the original MFT. The challenges of managing the flocculated product demand a reassessment of deposition methods and design layouts of the management facilities. This paper collates some ideas, supported by industry research, in this regard. It is hoped these ideas are debated in the industry, trialled, improved upon, and ultimately form the basis of more efficient and cost-effective tailings management in the oil sands industry. It remains for the industry to debate the ideas in this paper. And then on the basis of the debate, test the materials, undertake calculations, and hence move into the field to undertake a full-scale test of the approach. In the absence of full-scale field testing, we encourage more topic-specific testing, analysis, and publication. Thus we may collate the information and use it in a critical way to evaluate the ideas of this paper. We conclude that if we are ever to build large, high facilities for treated tailings, the ideas of this paper and others hopefully prompted by this paper will have to be developed in conjunction with a major focus on the engineering design and practical operation of the cells. The future for management of polymer-flocculated tailings is bright. But the path forward is not clear. This paper is our attempt to shine some light on the opportunities for researchers, consultants, polymer Paste 2014, Vancouver, Canada 17

18 OSD: a paradigm for the successful management of treated MFT J. Caldwell, A. Revington, G. McPhail and L. Charlebois suppliers, oil sand companies, and the industry as a whole to work together to advance to practical and cost-effective management of such tailings. References Beier, N., Alostaz, M. and Sego, D. (2009) Natural dewatering strategies for oil sands fine tailings, in Proceedings 13th International Conference on Tailings and Mine Waste, 1 4 November 2009, Banff, Canada, pp Fredlund, M.D., Xu, L. and Hammami, A. (2014) Numerical modeling of multi-lift thickened tailings considering evaporation, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie and D. Van Zyl (eds), 9 12 June 2014, Vancouver, Canada, InfoMine, Vancouver. Gidley, I.D.C. and Jeeravipoolvarn, S.S. (2014) Key mechanisms for oil sand fine tailings deposits, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie and D. Van Zyl (eds), 9 12 June 2014, Vancouver, Canada, InfoMine, Vancouver. Innocent-Bernard, T., Simms, P., Sedgwick, A., Kaminsky, H. and Yang, X. (2013) Influence of surface cracking and salinity on evaporation in an oil sands thickened tailings, in Proceedings 17th International Conference on Tailings and Mine Waste, 3 6 November 2013, Banff, Canada. Kabwe, L., Ward Wilson, G. and Donahue, R. (2013) Determination of geotechnical properties of in-line flocculated fine tailings for oil sands reclamation, in Proceedings 17th International Conference on Tailings and Mine Waste, 3 6 November 2013, Banff, Canada. Kupper, A.G., Hurndall, B., Morgenstern, N., Sobkowicz, J., Abeda, W., Baldwin, G. and Yazdanpanah, S. (2013) De-licensing oil sands tailings dams when is a dam no longer a dam? In Proceedings 17th International Conference on Tailings and Mine Waste, 3 6 November 2013, Banff, Canada. Li, H. (2014) Field farming trials of bauxite residue, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie and D. Van Zyl (eds), 9 12 June 2014, Vancouver, Canada, InfoMine. Moffett, R.H. (2010) Treatment of oil sands mature fine tailings with silica, in Proceedings 2nd International Oil Sands Tailings Conference, D. Sego and N. Beier (eds), 5 8 December 2010, Edmonton, Canada, University of Alberta Geotechnical Centre, Edmonton, pp Moffett, R.H., Odle, J.A. and Moore, T.W. (2014) Self-weight consolidation of silica treated mature fine tailings in a 10 metre column, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie and D. Van Zyl (eds), 9 12 June 2014, Vancouver, Canada, InfoMine, Vancouver. Munro, L. and Smirk, D. (2013) Mud farming of fine tailings application and benefits of MudMaster technology, in Proceedings 13th International Conference on Tailings and Mine Waste, 1 4 November 2009, Banff, Canada. Reid, D., Fourie, A. and Adkins, S. (2014) Polymer modified tailings deposition geotechnical effects, a summary and update, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie, D. Van Zyl and J. Caldwell (eds), 9 12 June 2014, Vancouver, Canada, InfoMine. Sobkowicz, J.C. (2013) Developments in treating and dewatering oil sand tailings, in Proceedings 16th International Seminar on Paste and Thickened Tailings (Paste13), R.J. Jewell, A.B. Fourie, J. Caldwell and J. 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Jewell (eds), March 2007, Perth, Australia, Australian Centre for Geomechanics, Perth. Yan, Y., Van Tol, F. and Van Paassen, L. (2012) Aspects of the behaviour of fine oil sands tailings during atmospheric drying, in Proceedings 16th International Conference on Tailings and Mine Waste, October, 2012, Keystone, Colorado, USA. Zhang, J., Melanson, A., Revington, A. and Wells, S. (2014) Mechanical dewatering of Suncor fine MFT oilsands tailings, submitted for publication in Proceedings 17th International Seminar on Paste and Thickened Tailings (Paste14), R.J. Jewell, A.B. Fourie and D. Van Zyl (eds), 9 12 June 2014, Vancouver, Canada, InfoMine, Paste 2014, Vancouver, Canada