Geotechnical Evaluation of Mine Tailings for Improved Dewatering

采矿作业产生大量尾矿(工艺水中的胶体悬浮物)，在其整个生命周期中构成巨大挑战。从围护设施的设计到回收，尾矿的岩土性质受到矿石地质、化学提取、泥浆处理和环境气候的影响。细粒尾矿和池塘中高度污染的液体的沉降速度缓慢，要求对围堵结构进行数十年的仔细管理。由此产生的低沉淀量降低了蓄水池的存储能力，以容纳矿场的新尾矿库存。为了最大限度地减少其环境足迹，采矿业主动修改其废物管理做法。最近从传统废物处理的转变是生产尾矿流，大部分处理水被去除并回收用于提取。申请者的研究计划通过开发(基于科学原理)改进尾矿脱水的岩土工程框架来支持这一范式转变。在饱和和非饱和条件下，我们将从微观力学和微观结构的角度研究体积变化过程中渗流在多孔介质中的基本概念。短期目标(在未来五年内)是设计具有改善压缩流变性的聚合物改性尾矿，并评估在大应变固结和蒸发干燥条件下的尾矿脱水。将采用专门的实验室研究技术和数值模拟方法来捕捉胶体浆液的独特特征，即：电化学相互作用、聚合物絮凝、大应变和演变的微观结构。这种新的方法是对岩土工程领域的扩展，岩土工程一般通过假设土材料是惰性的来处理基于载荷-变形的分析。这种对尾矿脱水的基本了解对于制定可持续的(成本效益高、环境友好和社会可行)战略至关重要，在新矿和现有矿的运营、关闭和复垦过程中进行水和能源管理。所提出的研究方法(针对尾矿开发)可应用于钻井泥浆、疏浚材料、泥浆墙和海洋沉积物。同样，尾矿改善对采矿业的预期技术和社会经济效益包括减少矿石选矿过程中的用水量，加强工艺水的回收，减少尾矿中的化学污染物，以及增加围护设施的存储容量。最后，培训高素质的专业人员将对采矿业在经济发展和环境遵守方面特别有利。

Mining operations generate large volumes of tailings (colloidal suspension in process water) presenting significant challenges throughout their lifecycle. From design to reclamation of containment facilities, the geotechnical properties of the tailings are influenced by ore geology, chemical extraction, slurry disposal, and ambient climate. The slow settling rate of the fine-grained tailings and the highly contaminated liquid in the ponds requires that the containment structures be carefully managed for decades. The resulting low sediment volume reduces the storage capacity of an impoundment to accommodate the new tailings inventory at a mine site. To minimize its environmental footprint, the mining industry proactively modifies its waste management practices. The recent shift from conventional waste handling is to produce tailings streams with the bulk of the processing water removed and recycled back for extraction. The applicant's research program supports this paradigm change by developing a geotechnical engineering framework (based on scientific rationale) for improved tailings dewatering. The basic concepts of flow through porous media during volume change will be investigated in light of micromechanics and microstructure under both saturated and unsaturated conditions. The short-term (within the next five years) objectives are to devise polymer-modified tailings with improved compression rheology and to assess tailings dewatering under large-strain consolidation and evaporative desiccation. Specialized laboratory investigation techniques and numerical modeling approaches will be adopted to capture the unique features of colloidal slurries, namely: electrochemical interactions, polymeric flocculation, large strains, and evolving microstructure. This novel approach is an extension to the field of geotechnical engineering that generally deals with load-deformation based analyses by assuming that earthen materials are inert. Such a fundamental understanding of tailings dewatering will be critical in developing sustainable (cost effective, environmentally friendly, and socially viable) strategies for water and energy management during operation, closure, and reclamation of new and existing mines. The proposed research methods (developed for mine tailings) can be applied to drilling muds, dredged materials, slurry walls, and marine deposits. Likewise, the expected technological and socio-economic benefits of tailings amelioration to the mining industry include reduced water consumption during ore beneficiation, enhanced reclamation of process water, reduced chemical pollutants in tailings, and increased storage capacity in containment facilities. Finally, the training of highly qualified professionals will be particularly beneficial for the mining industry with respect to both economic development and environmental compliance.