Disposal of iron tailings in reservoirs: a GPR application

A large volume of waste is generated by iron mining in Brazil, and the amount has been rapidly increasing. The waste is usually stored in large piles or in reservoirs formed by tailings dams, which occupy large areas in the mining complex. The limitation of natural resources and of new areas for waste disposal has led to change in paradigms. This study therefore aimed to apply a geophysical technique, known as Ground Penetrating Radar (GPR), in order to define sedimentation patterns in the subsurface reservoir created by Diogo's tailings dam in Rio Piracicaba in Minas Gerais, Brazil. To assist the recognition of patterns captured by the GPR, subsurface material samples were collected and analyzed for mineralogical composition, moisture content, electrical conductivity, mineralogical analysis, particle size, X-Ray Diffraction and X-Ray Fluorescence. The results indicated that areas with tailings that had high concentrations of hematite (around 60% in the mineralogical analysis) altered the reflection patterns. The presence of water generated some multiple reflections, which were less significant in shallower sites with more waste and more significant in deeper sites with less waste. In general, the application of the GPR was feasible in aquatic environments with rich subsurface hematite deposits.巴西铁矿开采会产生大量尾矿，且排放量正快速攀升。这类尾矿通常堆存于大型尾矿堆或尾矿坝构筑的库池中，占用矿区内大片土地。受自然资源总量限制与新增尾矿处置用地匮乏的双重约束，行业发展范式亟需转变。本研究旨在应用探地雷达（Ground Penetrating Radar，GPR）技术，对巴西米纳斯吉拉斯州皮拉西卡巴河（Rio Piracicaba）流域迪奥戈尾矿坝所形成的地下库池的沉积模式进行系统界定。为辅助识别探地雷达所捕获的沉积特征，研究人员采集了地下物料样本，并对其矿物组成、含水率、电导率、粒度分布、X射线衍射（X-Ray Diffraction）及X射线荧光光谱（X-Ray Fluorescence）开展了多维度分析。结果显示，赤铁矿（hematite）浓度较高（矿物分析中占比约60%）的尾矿区域会显著改变雷达反射模式。水体的存在会引发一定程度的多次反射信号，这类干扰在尾矿富集的浅水区影响相对较弱，而在尾矿占比较低的深水区则更为明显。总体而言，探地雷达在富含地下赤铁矿沉积的水生环境中具备切实可行的应用价值。