Identifying the mechanism of tailings dewatering by lime using surface vibrational spectroscopy

阿萨巴斯卡油砂是世界上最大的石油储量之一。然而，油砂开采过程中的一个挑战是如何处理大量的废料。这种废物被称为细 ** 尾矿，由细砂和粘土颗粒以及水、残油和 ** 提取中使用的添加剂和盐组成。在提取过程之后，大部分的水仍然与砂和粘土颗粒紧密结合，导致污泥稠度，这使得尾矿池的回收变得困难。实际上，水的 ** 量需要减少到<20质量%，以使尾矿固体能够承受土地复垦所需的重量 **（即维持表土、植被、道路等的能力）。目前还没有可靠的商业解决方案来实现油砂细尾矿的这一目标。然而，最近 **Graymont Western Canada Inc.（Graymont）是一家专门使用石灰的秘鲁公司，** 发现在加入石灰后进行加压处理可使尾矿易于脱水，产生含水量低、强度高的尾矿 ** 固体。为了理解这一显著现象，我们将利用我们实验室的表面特异性光谱技术：振动和频产生（SFG）。SFG对界面处有序的水量敏感，我们假设它是监测脱水的理想工具，脱水是从粘土和沙子表面释放的水。我们将探讨在存在和不存在碳酸氢盐的情况下，二氧化硅和粘土颗粒涂覆的二氧化硅上的表面相关水的量作为石灰浓度的函数。此外，我们将寻找直接在粘土/水 ** 界面相互作用的盐的签名，并将这些结果与尾矿沉降和脱水测量和表面电位 ** 分析相关联。最终目标是促进Graymont扩展到尾矿处理的基础上，我们 ** 的能力，表征尾矿脱水石灰的机制。这项合作将使加拿大受益，** 展示一种加速油砂尾矿池复垦的解决方案，最大限度地减少 ** 对伍德布法罗地区的环境影响。

The Athabasca oil sands are one of the largest oil reserves in the world. Yet one challenge in the oil sands**extraction process is how to deal with the large quantities of waste material. This waste, referred to as fine**tailings, consists of fine sand and clay particles as well as water, residual oil, and additives and salts used in**extraction. After the extraction process, a large fraction of water remains strongly bound to the sand and clay**particles, leading to a sludge consistency, which makes reclamation of tailings ponds difficult. Indeed, the**amount of water needs to be reduced to <20% by mass for the tailings solids to be able to bear the weight**required for land reclamation (i.e. ability to sustain top soil, vegetation, roads, etc.). There are currently no**commercial solutions to reliably achieve this target for oil sands fine tailings. However, recently researchers of**Graymont Western Canada Inc. (Graymont), a Canadian-owned company that specializes in the use of lime,**found that lime addition followed by pressure treatment led to facile dewatering of tailings, yielding tailings**solids with low water content and high strength. To understand this remarkable phenomenon, we will utilize**the surface-specific spectroscopic technique in our lab: vibrational sum frequency generation (SFG). SFG is**sensitive to the amount of water ordered at interfaces, and we hypothesize that it is the ideal tool to monitor**dewatering, which is water released from clay and sand surfaces. We will explore the amount of surface**associated water on silica and clay-particle coated silica as a function of lime concentration in the presence and**absence of bicarbonate. Furthermore, we will look for signatures of salts directly interacting at the clay/water**interface and correlate these results with tailings settling and dewatering measurements and surface potential**analysis. The ultimate goal is to facilitate the expansion of Graymont into tailings treatment based on our**ability to characterize the mechanism of tailings dewatering by lime. This collaboration will benefit Canada by**demonstrating a solution that accelerates the reclamation of oil sands tailing ponds, minimizing the**environmental impact on the Wood Buffalo region.