Towards integrating micro- and macro- scale processes and tools to improve dewatering and rheology assessments in soft and ultra-soft tailings

油砂开采尾矿水中含有超细粘土和残余沥青的悬浮颗粒。这些稳定的悬浮物需要很长时间才能沉降到池塘底部（大约10年）。因此，在较短的时间内减少尾矿的体积是一项重大挑战。此外，复垦土地的机械强度仍然较差，难以回归自然。在这些过程中添加增稠剂如聚丙烯酰胺（PAM）被认为是改善土壤固结的一种有吸引力的方法。尽管聚合物很便宜，但总体处理成本仍然很高。此外，这些聚合物的命运和运输问题，以及它们的生态毒性，仍然没有得到解决。目前还不清楚固结土的最终强度是否能达到阿尔伯塔省政府对岩土强度的最低要求。本项目旨在研究絮凝尾矿体系的微观结构对软、超软细粒矿床宏观脱水和流变特性的影响。絮凝体是一团粘土颗粒，如果加入的话，它是一种聚合物，形成软尾矿的基本结构。观察、理解和量化脱水和沉降（如剪切作用下）等关键过程中的絮凝机理，有可能在预测固结和沉降过程中迈出根本性的一大步，从而实现油砂尾矿的有效管理。如果成功的话，这将使流体尾矿的特定处理方法的选择（例如添加絮凝剂、混合和沉积速率）与长期脱水和强度性能（例如深层沉积物固结速率、砂分离、细粒捕获）之间存在直接关联，并有可能在未来推断长期回收目标。

The tailings water from oil sands extraction contains suspended particles of ultra-fine clays and residual bitumen. These stable suspensions take a long time to settle to the bottom of the ponds (> 10 years). Hence, reducing the volume of tailings in a shorter duration is a major challenge. In addition, the reclaimed land still has a poor mechanical strength for it to be returned to nature. Adding thickeners such as polyacrylamide (PAM) to these processes is considered an attractive method for improved soil consolidation. Even though the polymers are cheap, the overall treatment cost remains high. In addition, the issues of fate and transport of such polymers, as well as their ecotoxicity, are still not resolved. It is also not yet clear if the final strength of consolidated soil will meet the Alberta government's minimum requirements of geotechnical strength.The goal of this project is to investigate the influence of the micro-scale structure of the flocculated tailings systems on the macro-scale dewatering and rheological properties of soft and ultra-soft fines dominated deposits. Flocs are a clumped group of clay particles and, if added, a polymer that forms the basic structure of soft tailings. Observing, understanding and quantifying the flocculation mechanisms during critical processes such as dewatering and deposition (e.g. under shear) can potentially represent a fundamental big step forward in the prediction of consolidation and deposition operation, hence in the effective management of oil sands tailings. If successful, this allows direct correlation between the choice of a specific treatment of fluid tailings (e.g. addition of the flocculant, mixing and deposition rate) and long-term dewatering and strength performance (e.g. deep deposit consolidation rate, sand segregation, fines capture), with potential for future extrapolation to long-term reclamation objective.