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在尾矿流中实现>70重量%的固体，以便其准备好进行回收。过去几十年的研究表明，化学改良剂（例如，聚合物絮凝剂+凝结剂）和机械处理是实现这一最终目标所必需的。在机械处理技术中，加压过滤最有前途。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项案例研究表明，使用商用压滤机可以将典型的矿山尾矿脱水至>= 85重量%的固体。然而，当在油砂尾矿中使用相同的技术时，压滤饼仅达到约60重量%固体。 申请人过去的研究鉴定了超细级分，其从成熟的细粒尾矿中离心并含有超细亚微米粘土和水包沥青乳液液滴的混合物，作为成熟的细粒尾矿的差的压力过滤的主要原因。在拟议的项目中，我们将继续研究，以确定组成材料在超细部分（粘土类型，尺寸，沥青涂层和游离沥青）中的作用，并开发缓解技术，以消除其在压滤机操作中的不利影响。主要焦点不是试图分离/除去超细级分，而是选择性地聚集超细级分以形成高强度凝结物、絮凝物和/或地质聚合物。该研究有望使油砂尾矿通过压滤机快速脱水至> 70wt%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.