Maintaining Permeability for Continuous Mature Fine Tailings Dewatering

油砂尾矿一旦形成所谓的“成熟细尾矿”(MFT)，脱水速度极慢。这个 MFT累计运量超过8亿立方米，而且还在不断增加。在过去的几十年里 工业已经开发了许多脱水技术(复合尾矿、浓缩尾矿、在线 浓缩/稀提、离心、过滤)，以加快油砂尾矿的固液分离。 然而，处理效果普遍不理想，尾矿无法脱水 通过机械方式超过~55wt%固体，使目标&gt；=75wt%固体(回收所需) 似乎是不可能实现的。 我们最近的结果表明，油砂尾矿脱水的困难可以归因于 MFT中的残留沥青，而不是尾矿中细小的固体颗粒。我们的结果表明， 35wt%细粒高岭土(D50=4µm)的水泥浆可以很容易地过滤到~70wt%的固体，使用50g/t 6巴压力下的聚丙烯酰胺(PAM)。然而，在掺入3wt%的残留沥青后， 在PAM浓度为1500g/t时，高岭土浆液只能过滤到~60wt%的固体含量，表现出与MFT相似的特性。 基于这些结果，我们提出了一个问题：通常使用的PAM絮凝剂是处理 残留的沥青呢？在拟议的项目中，我们将回答这个问题，并确定适当的活页夹以 缓解残留沥青的不利影响。研究技术将包括：1)JAR测试以 评价潜在的沥青粘结剂与从MFT中分离出的残留沥青的相互作用；2)等温 用滴定量热法研究残留沥青与沥青的结合强度 粘结剂，以及细固体和沥青粘结剂之间；3)MFT处理后的压滤机试验 观察沥青粘结剂的脱水效果和达到的滤饼固含量；4)微电脑 用断层扫描和低温扫描电子显微镜研究滤饼的孔结构 治疗，并调查脱水性能差和改善的原因。

Oil sands tailings dewater extremely slowly once they form the so-called "mature fine tailings" (MFT). The accumulated MFT volume is over 800 million cubic meters and counting. Over the last few decades the industry has developed a number of dewatering techniques (composite tailings, thickened tailings, in-line thickening/thin lift, centrifugation, filtration) to speed up the solid-liquid separation of the oil sands tailings. However, the performance of treatment is generally unsatisfactory, and the tailings could not be dewatered beyond ~55 wt% solids by mechanical means, making the target of >=75 wt% solids (required for reclamation) seem un-achievable. Our recent results show that the difficulty of dewatering the oil sands tailings could be attributed to the residual bitumen in MFT rather than the small size of the fine solids in the tailings. Our results show that an aqueous slurry of 35 wt% fine kaolinite (d50 = 4 µm) could easily filter to ~70 wt% solids using 50 g/t polyacrylamide (PAM) under 6 bar pressure. However, after blending in 3 wt% of the residual bitumen, the kaolinite slurry could only be filtered to ~60 wt% solids at >1,500 g/t PAM, behaving like MFT. Based on these results, we ask the question: are the typically used PAM flocculants the best in dealing with the residual bitumen? In the proposed project, we will answer this question and identify appropriate binders to alleviate the detrimental effect of the residual bitumen. The research techniques will include: 1) jar tests to evaluate the interaction of potential bitumen binders with residual bitumen isolated from MFT; 2) isothermal titration calorimetric (ITC) study to investigate the binding strength between residual bitumen and bitumen binders, and between fine solids and bitumen binders; 3) filter press tests of the MFT after treatment by the bitumen binders to observe the dewatering effect and the achieved cake % solids content; 4) micro computed tomography and cryogenic scanning electron microscopy to study the pore structures of the filter cake after the treatment, and to investigate the reasons for the poor and improved dewatering performances.