Cyclic Freeze-Thaw to Assist the Dewatering of Oil Sand Tailings

在加拿大油砂中开采沥青会产生大量流动的细尾矿，这是一种对脱水和固结提出重大挑战的废物。截至2018年，加拿大的尾矿库存超过12.5亿立方米，找到一个全面、环保的尾矿管理解决方案是加拿大采矿业的首要任务。拟议的研究调查了利用阿尔伯塔北部自然冬季气候的潜力，以协助从尾矿固体中分离水。在野外的冰冻条件下，一维温度梯度在地面缓慢移动，并将水分收集到一个被称为冰透镜的网状网络中。春天解冻时，冰透镜融化，形成通道，水通过通道释放出来。以往，在实验台上复制现场条件既昂贵又耗时，而且生成数据的速度也很慢。本研究旨在利用初步冻融研究的资金和发现，对利用自然气候循环的尾矿脱水潜力进行更全面的调查，并制定程序，在实验规模上准确、经济地复制现场冻结条件，并及时获得结果。通过对冬季自然条件的适当模拟，研究了絮凝剂和絮凝剂添加量对浓缩尾矿冻结深度和冻结速度的影响。一旦方法建立并确认是成功的，将进一步研究最大化冻融脱水效益的尾矿放置策略。最后，这个项目为研究人员和行业之间的知识和经验的交叉授粉提供了一个极好的机会。本研究建立的程序将有助于未来的一维温度梯度复制研究以及基于气候的尾矿沉积物降水方法的研究。

The mining of bitumen in Canada's oil sands generates large volumes of fluid fine tailings, a waste materialwhich presents significant challenges to de-watering and consolidation. With over 1,250 million cubic metres of tailings inventory as of 2018, finding a holistic and environmentally responsible solution to tailingsmanagement is a top priority for the Canadian mining industry. The proposed study investigates the potential for utilizing the natural winter climate of northern Alberta to assist the separation of water from tailings solids. Under freezing conditions in the field, a one-dimensional temperature gradient moves slowly through theground, and collects moisture into a reticulated network known as an ice lens. Upon spring thaw, the ice lensesmelt and form channels by which water is released. The replication of field conditions at the laboratory bench scale have historically been expensive and time consuming, and generates data slowly.The present study aims to leverage the funds and findings of a preliminary freeze-thaw study into a more complete investigation into tailings de-watering potential using natural climate cycles, and to develop theprocedures to accurately and economically replicate field freezing conditions at the bench scale, with results obtainable in a timely manner. Through the proper emulation of natural winter conditions, the present researchaims to investigate the effect of flocculant and coagulant addition on the depth to, and speed at which,thickened tailings can freeze. Once the methodologies are established and confirmed to be successful, tailings placement strategies to maximize freeze-thaw de-watering benefits will be further investigated.Finally, this project presents an excellent opportunity for the cross-pollination of knowledge and experience between researchers and industry. The procedures developed in this study will benefit future studies inreplicating one-dimensional temperature gradients, and studies on climate-based methods of tailings sediment de-watering.