Department of Civil Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada.
Department of Chemistry, Queen's University, Kingston, ON, K7L 3N6, Canada.
Environ Sci Pollut Res Int. 2023 Jan;30(4):8868-8882. doi: 10.1007/s11356-022-22316-1. Epub 2022 Sep 15.
Sustainable long-term solutions to managing tailings storage facilities (TSFs) are integral for mines to operate in a safe and environmentally responsible manner. The long-term storage of subaqueous tailings can pose significant safety, environmental, and economic risks; therefore, alternative containment strategies for maintaining geochemical stability of reactive materials must be explored. In this study, the physical and geochemical stabilization of coal tailings using microbially induced calcite precipitation (MICP) was evaluated at a laboratory pilot scale. Three application techniques simulated commonly used agricultural approaches and equipment that could be deployed for field-scale treatment: spraying on treatment solutions with irrigation sprinklers, mixing tailings and treatment solutions with a rototiller, and distributing treatment solutions via shallow trenches using an excavator ripper. Test cells containing 1.0 × 1.0 × 0.5 m of tailings were treated with ureolytic bacteria (Sporosarcina pasteurii) and cementation solutions composed of urea and calcium chloride for 28 days. Penetrometer tests were performed following incubation to evaluate the extent of cementation. The spray-on application method showed the greatest strength improvement, with in an increase in surface strength of more than 50% for the 28-day testing period. The distribution of treatment solution using trenches was found to be less effective and resulted in greater variability in particle size distribution of treated tailings and would not be recommended for use in the field. The use of rototilling equipment provided a homogenous distribution of treatment solution; however, the disruption to the tailings material was less effective for facilitating effective cementation. Bacterial plate counts of soil samples indicated that S. pasteurii cultures remained viable in a tailings environment for 28 days at 18 °C and near-neutral pH. The treatment was also found to stabilize the pH of tailings porewater sampled over the 28-day incubation period, suggesting the potential for the treatment to provide short-term geochemical stability under unsaturated conditions.
管理尾矿储存设施 (TSF) 的可持续长期解决方案是矿山安全和环保运营的关键。水下尾矿的长期储存可能会带来重大的安全、环境和经济风险；因此，必须探索替代的封存策略来维持反应性材料的地球化学稳定性。在这项研究中，采用微生物诱导碳酸钙沉淀 (MICP) 对煤尾矿进行了实验室中试规模的物理和地球化学稳定化研究。三种应用技术模拟了常用的农业方法和设备，可用于现场处理：用灌溉喷头将处理溶液喷洒在处理溶液上，用旋耕机混合尾矿和处理溶液，以及用挖掘机铲斗在浅沟中分配处理溶液。含有 1.0 × 1.0 × 0.5 m 尾矿的测试单元用脲酶细菌 (Sporosarcina pasteurii) 和由尿素和氯化钙组成的胶结溶液处理 28 天。孵育后进行贯入试验以评估胶结程度。喷涂应用方法显示出最大的强度提高，在 28 天测试期间，表面强度增加了 50%以上。发现使用沟渠分配处理溶液的效果较差，处理后的尾矿颗粒分布变化较大，不建议在现场使用。旋耕设备的使用提供了处理溶液的均匀分布；然而，对尾矿材料的破坏效果较差，不利于有效胶结。土壤样品的细菌平板计数表明，在 18°C 和接近中性 pH 的条件下，S. pasteurii 培养物在尾矿环境中可存活 28 天。处理还发现稳定了在 28 天孵育期间采集的尾矿孔隙水的 pH 值，表明该处理有潜力在不饱和条件下提供短期地球化学稳定性。
