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

加拿大油砂中的沥青开采产生了大量流动的细粒尾矿，这是一种废物，对脱水和固结带来了巨大的挑战。截至2018年，加拿大尾矿库存超过12.5亿立方米，找到对环境负责的整体尾矿管理解决方案是加拿大采矿业的当务之急。这项拟议的研究调查了利用艾伯塔省北部的自然冬季气候来帮助从尾矿固体中分离水的可能性。在野外冰冻的条件下，一维的温度梯度在地面上缓慢移动，并将水分收集到一个被称为冰透镜的网状网络中。当春天融化时，冰透镜融化并形成释放水的通道。实验室规模的现场条件复制历来既昂贵又耗时，而且生成数据缓慢。本研究旨在利用初步冻融研究的资金和结果，利用自然气候循环对尾矿脱水潜力进行更全面的调查，并制定程序，准确和经济地复制实验室规模的现场冻结条件，并及时获得结果。通过适当模拟自然冬季条件，研究了絮凝剂和混凝剂的加入对浓缩尾矿冻结深度和冻结速度的影响。一旦方法建立并被证实是成功的，将进一步研究尾矿放置策略，以最大限度地增加冻融脱水的好处。最后，该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。这项研究开发的程序将有助于今后复制一维温度梯度的研究，以及基于气候的尾矿沉积物脱水方法的研究。

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.