Influence of desulfurized tailings cover heterogeneity and variability on long term performance of mine site reclamation

脱硫尾矿覆盖异质性和变异性对矿场复垦长期绩效的影响

• 批准号: RGPIN-2020-06354
• 负责人: Demers, Isabelle
• 金额: $ 1.89万
• 依托单位: Université du Québec en Abitibi-Témiscamingue
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741159
• 关键词: Influence; desulfurized; tailings; cover; heterogeneity

Reclamation of acid generating mine tailings storage facilities is a challenge for the mining industry. Traditional methods are revisited to incorporate issues such as climate change, resource scarcity, and responsible mining. The reuse of inert tailings, or tailings made unreactive by desulfurization, as cover material in a reclamation scenario, has been a focus of research for the past decade. Mining companies now seriously consider desulfurization for reclamation as part of responsible mine development. However, desulfurization is not often used in operating mine sites for production of cover material. Full-scale implementation of desulfurized tailings as monolayer covers was performed on a few sites in Canada. Challenges were identified on full-scale covers, mainly related to variability of desulfurized tailings sulfur content and particle size distribution. Indeed, on a cover deposited hydraulically as a slurry, significant particle size segregation occurs, which could affect the performance of the cover. Furthermore, desulfurized tailings may evolve over their service life as cover material. Geochemical evolution may occur because of residual sulfide consumption within the cover. Other elements may be released over time from the cover and affect effluent quality (e.g. Zn, As). The new conditions in the covered sulfidic tailings, while preventing sulfides oxidation, may trigger other reactions leading to the release of metals. Previous numerical modeling provided preliminary evaluation of cover performance using estimated average cover properties that did not change with time. A long-term perspective on cover performance needs to include variability in cover material properties, and specifically for desulfurized tailings used as cover material, since reclaimed sites have an indefinite service life. Desulfurized tailings as cover material is close to being implemented at the full-scale level as a successful reclamation scenario. The research program aims to fill the knowledge gaps related to the effect of cover heterogeneity and evolution on long term performance through three main objectives: (1) Establish a numerical model of the hydrogeochemical behaviour of a desulfurized tailings cover system in 2 and 3 dimensions, considering heterogeneity and spatial variability in chemical composition and particle size distribution; (2) Evaluate the mid and long term performance of a desulfurized tailings cover system considering the evolution of geochemical conditions in the acid-generating tailings and in the desulfurized tailings cover; (3) Compare the behaviour of a desulfurized tailings cover system from laboratory results and numerical predictions to full scale cover. The methodology that will be used include laboratory experiments, field instrumentation and measurements, and numerical modeling. It is expected to train 1 PhD, 1 MSc, 1 PDF and 3 internship students over the course of this research program.

产酸矿山尾矿储存设施的回收是采矿业的一项挑战。传统方法被重新审视，以纳入气候变化、资源稀缺和负责任采矿等问题。惰性尾矿的再利用，或通过脱硫变得不反应的尾矿，作为复垦方案中的覆盖材料，在过去十年中一直是研究的焦点。矿业公司现在认真考虑脱硫回收作为负责任的矿山开发的一部分。然而，脱硫并不经常用于生产覆盖材料的运营矿场。在加拿大的几个地点全面实施了脱硫尾矿单层覆盖。确定了全尺寸覆盖的挑战，主要涉及脱硫尾矿硫含量和粒度分布的可变性。实际上，在作为浆料液压沉积的覆盖物上，发生显著的颗粒尺寸偏析，这可能影响覆盖物的性能。此外，脱硫尾矿可能会在其使用寿命期间演变为覆盖材料。地球化学演化可能是由于覆盖层内残余硫化物的消耗而发生的。随着时间的推移，其他元素可能会从覆盖物中释放出来，并影响污水质量（例如Zn，As）。覆盖的硫化物尾矿中的新条件在防止硫化物氧化的同时，可能引发导致金属释放的其他反应。以前的数值模拟提供了初步评估的覆盖性能，估计平均覆盖性能不随时间变化。覆盖性能的长期视角需要包括覆盖材料特性的变化，特别是用于覆盖材料的脱硫尾矿，因为回收场地的使用寿命是不确定的。 脱硫尾矿作为覆盖材料，作为一种成功的复垦方案，已接近全面实施。该研究计划旨在填补覆盖层非均匀性和演化对长期性能影响的相关知识空白，主要目标有三个：（1）建立脱硫尾矿覆盖层系统的二维和三维水文地球化学行为的数值模型，考虑化学成分和粒度分布的非均匀性和空间变异性;（2）考虑到产酸尾矿和脱硫尾矿覆盖层中地球化学条件的演变，评估脱硫尾矿覆盖层系统的中长期性能;（3）比较实验室结果和数值预测与全尺寸覆盖层的脱硫尾矿覆盖层系统的行为。将使用的方法包括实验室实验，现场仪器和测量，以及数值模拟。预计将在本研究计划的过程中培养1名博士，1名硕士，1名PDF和3名实习生。