Geotechnical Evaluation of Mine Tailings for Improved Dewatering

采矿作业会产生大量尾矿（工艺用水中的胶体悬浮液），在其整个生命周期中带来重大挑战。从设计到围隔设施的改造，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。细粒尾矿和池中高度污染的液体沉降速度缓慢，需要数十年来仔细管理安全壳结构。由此产生的低沉积物体积降低了蓄水池的储存能力，以容纳矿场的新尾矿库存。为尽量减少对环境的影响，采矿业积极修改其废物管理做法。最近从传统的废物处理转变为产生尾矿流，其中大部分处理水被去除并回收用于提取。申请人的研究计划通过开发用于改进尾矿脱水的岩土工程框架（基于科学原理）来支持这种范式变化。在饱和和非饱和条件下，将根据微观力学和微观结构研究体积变化期间通过多孔介质的流动的基本概念。短期（在未来五年内）的目标是设计具有改进的压缩流变性的聚合物改性尾矿，并评估大应变固结和蒸发干燥下的尾矿脱水。专门的实验室调查技术和数值模拟方法将被采用，以捕捉胶体浆料的独特功能，即：电化学相互作用，聚合物絮凝，大应变，和不断变化的微观结构。这种新的方法是岩土工程领域的扩展，通常处理基于荷载变形的分析，假设土材料是惰性的。这种对尾矿脱水的基本理解将是至关重要的，在开发可持续的（成本效益，环境友好，社会可行的）水和能源管理战略，在运营，关闭，并回收新的和现有的矿山。建议的研究方法（开发的尾矿）可以应用于钻井泥浆，疏浚材料，泥浆墙，和海洋沉积物。同样，尾矿改良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水消耗，加强工艺用水的回收，减少尾矿中的化学污染物，以及增加密封设施的储存能力。最后，培训高素质的专业人员将特别有利于采矿业的经济发展和环境合规。

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.