Impact of differential settlement of oil sand fine tailings on reclamation covers

油砂细尾矿差异沉降对复垦覆盖层的影响

• 批准号: RGPIN-2019-04573
• 负责人: Beier, Nicholas
• 金额: $ 2.26万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749024
• 关键词: Impact; differential; settlement; oil; sand

This research program aims to ensure the sustainable development and ultimate reclamation of one of Canada's greatest energy resources, the oil sands. Alberta's oil sand mining region is dominated by several storage ponds containing nearly 1 billion m3 of a clayey mud-like slurry waste called fluid fine tailings (FFT). The oil sands industry has implemented various processes to treat the FFT with some using chemicals and mechanical equipment. The resulting treated tailings (T-FFT) are then placed behind dams creating vast deep tailings ponds. These tailings will then undergo substantial settlement estimated to be 30-50% of the initial height over a period of decades to centuries. Due to the size and inherent variability of the tailings properties within the ponds, this settlement is expected to occur at different rates and magnitudes across the tailings ponds, resulting in what is known as differential settlement (dS) of the tailings surface. The rate and extent of dS has not been thoroughly investigated and quantified for oil sands fine tailings ponds. Significant research and detailed closure and reclamation designs have been undertaken for various soil structures, containment dams or sandy tailings deposits at the oil sands mines. However, none of these deposits will undergo dS to the extent of T-FFT. The reclamation landforms planned for T-FFT deposits include wetlands, ponds, lakes and forests. Should dS continue after the reclamation covers and final landforms are constructed on these T-FFT deposits, there may be detrimental impacts to the surface water balance, groundwater system and overall physical stability. These impacts may ultimately delay or prevent a mine site from achieving its reclamation goal of a "maintenance-free, self-sustaining" landscape. An improved understanding of the impact of dS will lead to more resilient designs of closure landforms. The long-term goals of this research program aim to develop risk management and design approaches to improve reclamation and closure of tailings dams in Canada. The proposed research program will investigate the potential dS arising from various T-FFT deposits, the resulting impact on proposed closure landforms, and quantify the risk to successful closure. Specific objectives of this research program are to: 1) Quantify the dS across T-FFT deposits and its relation to the physical properties of T-FFT. 2) Evaluate the impact of settlement on reclamation covers on tailings undergoing dS. A combination of advanced numerical modeling and laboratory testing in a unique geotechnical testing facility (centrifuge) will be used to estimate the variability in dS in T-FFT and the resulting impact on reclamation covers. The results from the proposed research will be immediately available for oil sand companies and regulators to estimate maintenance and monitoring requirements, evaluate the risk of current tailings pond closure designs, and provide guidance on enhanced design alternatives.

该研究计划旨在确保加拿大最大的能源资源之一油砂的可持续发展和最终回收。阿尔伯塔的油砂开采区主要是几个储存池，其中含有近10亿立方米的粘土状泥浆废物，称为流体细尾矿（FFT）。油砂工业已经实施了各种方法来处理FFT，其中一些使用化学品和机械设备。然后将得到的处理过的尾矿（T-FFT）放置在大坝后面，形成巨大的深尾矿池。这些尾矿将在几十年到几个世纪的时间内经历大量沉降，估计为初始高度的30-50%。由于池内尾矿性质的大小和固有可变性，预计这种沉降在整个尾矿池中以不同的速率和幅度发生，导致所谓的尾矿表面的差异沉降（dS）。尚未对油砂细尾矿池的dS速率和程度进行彻底调查和量化。已对油砂矿的各种土壤结构、拦水坝或桑迪尾矿沉积物进行了大量研究和详细的封闭和复垦设计。然而，这些沉积物中没有一个将经历dS到T-FFT的程度。T-FFT矿床计划的复垦地貌包括湿地、池塘、湖泊和森林。如果在这些T-FFT沉积物上建造填海覆盖层和最终地貌后继续进行dS，可能会对地表水平衡，地下水系统和整体物理稳定性产生不利影响。这些影响最终可能会延迟或阻止矿区实现其“免维护、自我维持”景观的复垦目标。更好地理解dS的影响将导致更有弹性的设计关闭地貌。该研究计划的长期目标旨在开发风险管理和设计方法，以改善加拿大尾矿坝的复垦和关闭。拟议的研究计划将调查各种T-FFT沉积物产生的潜在dS，对拟议关闭地貌的影响，并量化成功关闭的风险。本研究计划的具体目标是：1）量化跨T-FFT沉积物的dS及其与T-FFT物理性质的关系。2)评估沉降对尾矿复垦覆盖层的影响。 先进的数值模拟和实验室测试在一个独特的土工试验设施（离心机）的组合将被用来估计在T-FFT的dS的变化和由此产生的影响填海覆盖。拟议研究的结果将立即提供给油砂公司和监管机构，以估计维护和监测要求，评估当前尾矿库关闭设计的风险，并为增强设计方案提供指导。