Flocculation and dewatering of oil sands tailings with hyperbranched functional polyolefins

阿尔伯塔省的油砂储量是加拿大重要的自然资源。它们是世界第三大原油来源国，仅次于沙特阿拉伯和委内瑞拉。不幸的是，加拿大人为使用这种宝贵的自然资源付出了高昂的环境代价。油砂行业采用的提取工艺，每加工一桶沥青，产生约1.5桶流体细粒尾矿。尾矿是水、沙子、粘土和残余沥青的混合物。尾矿被转移到池塘中，那里的沙子沉降很快，但细粘土在显著沉降之前仍然悬浮很长时间。多年后，形成一种稳定的悬浮液，其中含有约30%的细粘土，称为成熟的细尾矿。成熟的细粒尾矿具有酸奶的稠度。在这些池塘上走路或开车是不可能的。因此，他们占据的地区成为无法恢复的荒地。据估计，到2020年，我国成熟细粒尾砂累积量将超过10亿立方米。尾矿的持续收集在阿尔伯塔省造成了严重的环境问题，因为目前的处理技术不能显著减少遗留尾矿和新尾矿的体积。本项目将研制新型高分子絮凝剂，对尾矿库进行絮凝脱水处理。回收的水将被送回油砂提取过程中，而脱水的池塘将变得足够坚固，使其成为可通行的，允许在其上种植植被，从而回收以前的尾矿池浪费的土地。所提出的超支化功能聚乙烯以前从未用于处理油砂尾矿，但我们的初步结果表明，它们有可能解决现有尾矿处理技术面临的许多局限性。我们将确定这些聚合物的哪些特性可以控制尾矿絮凝和脱水，并将这些知识转移到油砂行业。由于油砂工业对加拿大经济的重大贡献和尾矿问题的严重性，拟议的研究项目具有很大的价值。

The oil sands reserves in Alberta are a major Canadian natural resource. They are the third largest source of crude oil in the world, only surpassed by those of Saudi Arabia and Venezuela. Unfortunately, Canadians pay a high environmental price to use this valuable natural resource. The extraction process adopted by the oil sands industry produces about 1.5 barrels of fluid fine tailings for every barrel of bitumen processed. Tailings are a mixture of water, sand, clays, and residual bitumen. The tailings are transferred to ponds where the sand settles fast, but the fine clays remain suspended for a long time before significant settling takes place. After many years, a stable suspension containing about 30 wt% of fine clays, called mature fine tailings, is formed. Mature fine tailings have the consistency of yogurt. It is not possible to walk or drive on top of these ponds. Consequently, the area they occupy becomes a wasteland that cannot be recovered. It has been estimated that the accumulated volume of mature fine tailings will exceed one billion cubic meters by 2020. The continuing collection of tailings has created a severe environmental problem in Alberta because the current treatment technologies cannot significantly reduce the volumes of legacy and fresh tailings. In this project, we will make novel polymer flocculants to treat tailing ponds by flocculation and dewatering. The recovered water will be sent back to the oil sands extraction process, while the dewatered ponds will become solid enough so that it becomes trafficable, allowing for vegetation to be planted on them, thus reclaiming the land wasted by the former tailing ponds. The proposed hyperbranched functional polyethylenes have never been used before to treat oil sands tailings, but our preliminary results show they can potentially solve many of the limitations faced by existing tailings treatment technologies. We will determine which properties of these polymers control tailings flocculation and dewatering, and will transfer this knowledge to the oil sands industry. The proposed research project has great value because of the significant contribution of the oil sands industry to the Canadian economy and the magnitude of the tailings problem.