Strengthening Floc Structure During Pressure Filtration of Flocculated Tailings

水的再循环和最大限度地减少油砂和矿物加工厂的细尾矿量是脱水操作的主要目标。脱水过程通常是作为一系列较小的相互连接的单元操作进行的，例如混凝-絮凝、浓缩、过滤或脱水，甚至在极端情况下进行热干燥，所有这些都在最终尾矿处置之前进行。这些阶段中的每一个仅回收一部分水，并且随着目标水分/水含量降低，脱水的难度增加。由于细颗粒固有地难以从水中分离，因此总体策略是通过一系列聚集过程（凝聚和絮凝）逐渐增加待从水中分离的固体的有效尺寸，所述聚集过程导致聚集体的快速沉降以形成增稠的沉积物（增稠），所述沉积物最终可以经历压滤和/或过滤。拟议的研究重点是从絮凝和增稠到过滤的过渡，主要目标是操纵絮凝沉淀物的物理化学性质（即，絮凝和增稠的产物），以改善随后的过滤阶段的性能。预计这一目标可以通过仔细添加选定的化学品来实现，这些化学品的作用是增强絮凝沉淀物对所施加压力的机械阻力，从而使水更容易从沉淀物中流出。由于尾矿处理和水循环可以说是油砂和矿物加工行业最紧迫的挑战，因此拟议研究的结果将导致更有效和更环保的尾矿处理方法。方法将涉及在一系列条件（pH值，离子强度）下稀释和浓缩矿物悬浮液的絮凝试验，然后对絮凝沉淀物进行压滤。沉积物的强度将通过流变测量进行评估。其他表面化学表征方法也将用于阐明所观察到的现象的机制。

Recycling of water and minimizing the volume of fine mineral tailings from oil sands and mineral processing plants are the main objectives of dewatering operations. The dewatering process is usually carried out as a series of smaller interconnected unit operations, such as coagulation-flocculation, thickening, filtration or centrifuging, and even thermal drying in extreme cases, all before final tailings disposal. Each of these stages recovers only a portion of water, and the difficulty of dewatering increases as the target moisture/water content decreases. Since fine particles are inherently difficult to separate from water, the overall strategy is to gradually increase the effective size of solids to be separated from water through a series of aggregation processes (coagulation and flocculation) that lead to fast settling of the aggregates to form a thickened sediment (thickening), which can finally undergo pressure filtration and/or centrifuging. The proposed research focuses on the transition from flocculation and thickening to filtration, and the main objective is to manipulate the physico-chemical properties of a flocculated sediment (i.e., product of flocculation and thickening) in order to improve the performance of the subsequent filtration stage. It is expected that this objective can be achieved through careful addition of selected chemicals whose role would be to enhance the mechanical resistance of the flocculated sediment to the applied pressure thus allowing water to more readily flow out of the sediment. Since tailings disposal and water recycling are arguably the most pressing challenges of the oil sands and mineral processing industries, the results of the proposed research will lead to more efficient and more environmentally friendly methods of tailings treatment.Methodology will involve flocculation tests in dilute and concentrated mineral suspensions under a range of condition (pH, ionic strength), followed by pressure filtration of the flocculated sediment. The strength of the sediment will be assessed through rheological measurements. Other surface-chemical characterization methods will also be used to elucidate the mechanisms of the observed phenomena.