Removal of hydrophobic bitumen-coated fine solids from NAE bitumen using water droplets with modified interfacial chemistry and bio-inspired polymers

加拿大的油砂储量位居世界第三，仅次于沙特阿拉伯和委内瑞拉。目前的油砂水基采油工艺面临着淡水需求量大、能源消耗和温室气体排放高、尾矿库面积大等日益紧迫的环境问题。在所谓的非水萃取（NAE）工艺中，使用有机溶剂代替水的研究已经得到了发展，因为NAE工艺可能不消耗淡水，产生干尾矿，并且导致低温室气体排放。然而，一个可行的NAE工艺的关键挑战之一是所产生的沥青产品的质量，其矿物固体含量不应超过0.03 wt%。油砂中的微细矿物固体，特别是粘土矿物，在NAE过程中容易向沥青溶剂产物中迁移。已有研究表明，沥青溶剂产品中少量的水（如油砂中天然存在的原生水）可以促进亲水性和双湿性细矿物固体的去除，但不能去除沥青包覆的细疏水性矿物固体。目前还没有一种经济有效的方法来去除这些细小固体以满足产品质量要求。在这项研究中，我们建议通过添加具有所需官能团和/或生物启发（如贻贝启发）聚合物的两亲性化学物质来调节固体/溶剂和溶剂/水界面的界面化学，以改变精细矿物固体的表面润湿性及其与水滴的相互作用。预计这些处理将促进细固体与水滴的聚集。利用先进的纳米力学工具，阐明沥青-溶剂产品中矿物固体、水滴和添加化学剂之间的基本表面相互作用机制。预计所提出的研究将为油砂工业提供一种有效和经济的方法来去除疏水沥青包覆的细固体，使其更接近商业上可行的NAE工艺。

Canada has the third largest oil reserves in the world after Saudi Arabia and Venezuela in the form of oil sands. The current water-based oil extraction processes from the oil sands are plagued with increasingly pressing environmental problems, namely high fresh water demand, high energy consumption and GHG emission, and large areas of tailings ponds. Research on replacing water using organic solvents, in a so-called nonaqueous extraction (NAE) process, has been gaining momentum as the NAE process potentially consumes no fresh water, generates dry tailings, and leads to low GHG emission. However, one of the key challenges in a feasible NAE process is the quality of the generated bitumen product, which should contain no more than 0.03 wt% mineral solids. The fine mineral solids in the oil sands, particularly clay minerals, tend to migrate to the bitumen-solvent product during the NAE process. Previous research has shown that a small amount of water (such as connate water naturally present in the oil sands) in the bitumen-solvent product could facilitate the removal of the hydrophilic and bi-wet fine mineral solids, but could not remove the fine hydrophobic bitumen-coated mineral solids. There is currently no efficient and economic method to remove these fine solids to meet the product quality requirement. In this research, we propose to modulate the interfacial chemistry of solid/solvent and solvent/water interfaces to alter the surface wettability of fine mineral solids and their interactions with the water drops, through the addition of amphiphilic chemicals with the desired functional groups and/or bio-inspired (e.g. mussel-inspired) polymers. It is anticipated that these treatment will facilitate the aggregation of the fine solids with water drops. The fundamental surface interaction mechanisms among mineral solids, water drops, and added chemical agents in bitumen-solvent product will be elucidated using advanced nanomechanical tools. It is expected that the proposed research will provide an effective and economic approach to the oil sands industry for the removal of the hydrophobic bitumen-coated fine solids, making it a step closer to a commercially feasible NAE process.