Mitigating the Adverse Effects of Ultrafines in Pressure Filtration of Oil Sands Tailings

油砂尾矿管理的最终目标是使尾矿流中的固体含量达到100 ~ 70 wt%，以便为回收做好准备。过去几十年的研究表明，要实现这一最终目标，需要化学改性（如高分子絮凝剂+混凝剂）和机械处理相结合。在机械处理技术中，压力过滤是最有前途的。在不列颠哥伦比亚省温哥华举行的2019年尾矿和矿山废物会议上报告的几个案例研究表明，使用商用压滤机可以将典型的矿山尾矿脱水至>= 85 wt%的固体。然而，当同样的技术用于油砂尾矿时，压滤饼的固体含量仅达到60%左右。申请人过去的研究发现，从成熟细粒尾矿中分离出来的超细粒，含有超细亚微米粘土和水包沥青乳液滴的混合物，是导致成熟细粒尾矿压滤不良的主要原因。在拟议的项目中，我们将继续研究超细馏分中组成材料（粘土类型、粒径、沥青涂层和游离沥青）的作用，并开发缓解技术，以消除它们在压滤机操作中的有害影响。主要重点不是试图分离/去除超细组分，而是选择性地聚集超细组分以形成高强度的混凝剂、絮凝体和/或土工聚合物。该研究有望使压滤机快速脱水油砂尾矿至bbb70 wt%固体在技术上和经济上可行。

The ultimate goal of oil sands tailings management is to achieve >70 wt% solids in the tailings stream so that it is ready for reclamation. Research in the past several decades indicates that a combination of chemical amendment (e.g., polymer flocculants + coagulants) and mechanical treatment is necessary to achieve this ultimate goal. Of the mechanical treatment techniques, pressure filtration holds the most promise. Several case studies reported in the Tailings & Mine Wastes 2019 Conference in Vancouver, BC, show that typical mine tailings could be dewatered to >= 85 wt% solids using commercial filter press. However, when the same technology was used in oil sands tailings, the pressure filtration cake only reached about 60 wt% solids. The applicants' past research identified an ultrafine fraction, which was centrifuged from mature fine tailings and contained a mix of ultrafine sub-micron clays and bitumen-in-water emulsion droplets, as the main reason for the poor pressure filtration of the mature fine tailings. In the proposed project, we would continue the research to identify the roles of the constituent materials in the ultrafine fraction (clay types, size, bitumen coating and free bitumen) and develop mitigation technologies to eliminate their detrimental effects in filter press operation. The main focus is not to attempt to separate/remove the ultrafine fraction, but to selectively aggregate the ultrafine fraction to form high strength coagula, flocs and/or geo-polymers. The research is expected to make rapid dewatering of the oil sands tailings to >70 wt% solids by filter press technically and economically feasible.