Biomediated Geomechanical Processes for Dust Mitigation and Monitoring at Mine Tailings Impoundments

尾矿库除尘和监测的生物介导地质力学过程

• 批准号: 1234126
• 负责人: Eric Seagren
• 金额: $ 20.29万
• 依托单位: Michigan Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1234126&HistoricalAwards=false
• 关键词: Biomediated; Geomechanical; Processes; Dust; Mitigation

Massive volumes of waste materials are produced annually by mining operations. A significant fraction of these materials is in the form of tailings that are discharged as a slurry and contained in earthen structures known as tailings disposal impoundments. These large earthen structures are subject to intense regulatory and public attention because of the hazards associated with the materials they contain. In particular, one of the key physical hazards associated with tailings in these impoundments is the air pollution from blowing dust. Conventional approaches for controlling the hazard associated with dust emissions have several limitations and potential negative side effects on human health and the environment. In addition, monitoring of mine tailings for susceptibility to dust emissions is limited and poses a long-term cost to the mining industry. Recent research using biomediated techniques for ground improvement have shown the effectiveness of using microorganism to improve the engineering properties of granular soils. However, the use of bioengineering on materials such as iron-mine tailings, presents many significant challenges such as dealing with micron and submicron particles, as well as techniques for application, distribution, and potential long-term water quality issues. Therefore, the overall goals of this project are two-fold. First, novel and sustainable, low-impact biogeoengineering practices for stabilization of mine tailings to mitigate dust emissions will be developed and tested. This will entail the engineered stimulation of biomediated cementation processes (e.g., calcium carbonate or iron precipitation) and/or artificial cryptogam (biological crust) formation. The resulting crust will improve the surface strength of mine tailings impoundments, reducing the potential for fugitive dust emissions, and thereby mitigating the associated hazards to human and environmental health. Second, these efforts will be coupled with innovative remote sensing techniques for monitoring the susceptibility of tailings to dust emissions. Specifically, thermal inertia computed from remotely sensed thermal images will be used for monitoring the effect of biomodification of mine tailings and to analyze the susceptibility of the tailings to dust emissions. These goals will be achieved via a series of bench-scale laboratory box model evaluations. Society will benefit in several ways from this application of biomediated geomechanical processes, and the development of remote sensing techniques for monitoring such near-surface processes. Mine tailings sites from active, inactive, and abandoned mine are observed throughout the world. These mine tailings remain un-vegetated for tens to hundreds of years, and are a significant source for emission of particulate matter. The particulate matter emissions are monitored in newly established mines, but the older sites remain unmonitored. Mine tailings and their associated metal contaminants, which are contained in large surface tailings impoundments, are prone to significant dust events, both in warm and cold weather climates. Some of the more dramatic dusting events occur in cold climates due to the sublimation of the frozen pore waters, also known as dry freezing, leaving a layer of desiccated (dry) tailings on frozen tailings, easily allowing the tailings to become airborne and a large source of fugitive dust. Dust control has been a significant and sensitive issue because of the effects of dusts on human living conditions. Dust causes human respiratory health problems (e.g., asthma, bronchitis, emphysema, etc.) and can lead to vehicle accidents due to poor visibility and road conditions. Correspondingly, there is need for effective, and economical dust mitigation techniques, as well as methods for monitoring tailings impoundments and predicting when dust events might occur.

采矿作业每年产生大量的废料。这些材料中有很大一部分以尾矿的形式排放，并包含在称为尾矿处置蓄水池的土制结构中。这些大型土结构受到严格的监管和公众的关注，因为它们所含的材料有危险。特别是，与这些水库中的尾矿有关的关键物理危害之一是吹尘造成的空气污染。控制与粉尘排放有关的危害的传统方法有一些局限性，并可能对人类健康和环境产生负面影响。此外，对尾矿易受粉尘排放影响的监测是有限的，给采矿业带来长期成本。近年来利用生物介导技术进行土壤改良的研究表明，利用微生物改善颗粒土的工程性质是有效的。然而，在诸如铁矿尾矿之类的材料上使用生物工程提出了许多重大挑战，例如处理微米和亚微米颗粒，以及应用、分布和潜在的长期水质问题的技术。因此，这个项目的总体目标是双重的。首先，将开发和测试用于稳定矿山尾矿以减少粉尘排放的新颖、可持续、低影响的生物地球工程实践。这将需要工程刺激生物介导胶结过程（例如，碳酸钙或铁沉淀）和/或人工隐壳（生物外壳）形成。所产生的结壳将提高矿山尾矿库的表面强度，减少逸散粉尘排放的可能性，从而减轻对人类和环境健康的相关危害。第二，这些努力将与监测尾矿易受粉尘排放影响的创新遥感技术相结合。具体来说，利用遥感热图像计算的热惯量来监测尾矿的生物改性效果，并分析尾矿对粉尘排放的敏感性。这些目标将通过一系列实验规模的实验室箱模型评估来实现。社会将在几个方面受益于这种生物介导的地质力学过程的应用，以及监测这种近地表过程的遥感技术的发展。世界各地都有活跃、不活跃和废弃矿山的尾矿场。这些尾矿数十年至数百年未被植被覆盖，是颗粒物排放的重要来源。新建立的矿井对颗粒物排放进行了监测，但旧的矿井则不进行监测。大型地表尾矿库中所含的尾矿及其伴生金属污染物，无论在温暖气候还是寒冷气候下，都容易发生重大粉尘事件。一些更戏剧性的粉尘事件发生在寒冷的气候中，由于冻结孔隙水的升华，也称为干冻结，在冻结的尾矿上留下一层干燥的（干）尾矿，容易使尾矿成为空气传播和逃逸粉尘的大来源。由于粉尘对人类生活条件的影响，粉尘控制一直是一个重要而敏感的问题。灰尘会引起人类呼吸系统健康问题（例如哮喘、支气管炎、肺气肿等），并会因能见度低和道路状况不佳而导致车辆事故。相应地，需要有效的、经济的降尘技术，以及监测尾矿库和预测何时可能发生粉尘事件的方法。