Abstract:
Tailings are one of the largest pollutant sources in the world. The wind and water leaching were often considered the main distribution tool of their pollutants. However, the carbonate crust precipitation has negated the trace toxic element (TTE) release. To identify the release mode of Pb, Zn, and Cd from mine wastes, the hydrodynamic evolution of waste piles was considered. The macroscopic and microscopic observation, the grain sizes, cohesion particles, density, hydraulic conductivity, and Pb, Zn, and Cd concentrations performed from eight drill cores of the two waste dumps and the principal component and the hierarchical cluster analysis showed that the physical properties of waste piles closely controlled the TTE mobility and migration from the tailings. The obtained data also showed that the upper carbonate layers were first eroded by wind and rainfall. Then, the formation of an impermeable carbonate crust limited the Pb, Zn, and Cd releases. However, the hydrodynamic evolution of the underneath layers was different. As the high pile waste sediments\' weight meaning the lithostatic pressure (Pl), the geostatic ratios (λ = Pf/Pl) were in DII and DIII dumps superior to 0.29 and 0.26, respectively. Therefore, the overpressured fluids increased the mineral dissolution, including the sulfides and carbonates of metals, and hydraulic fracturing that raised the percentages of the mobile TTE and migration indexes. By the secondary pore and fracture volumes, the polluted fluids were progressively channeled towards the underpressured marge (dumps edge) by repetitive (polyphase) fluid pulsations.
摘要:
尾矿是世界上最大的污染源之一。风和水浸通常被认为是其污染物的主要分布工具。然而,碳酸盐地壳沉淀抵消了痕量有毒元素(TTE)的释放。为了确定Pb的释放方式,Zn,和来自矿山废物的Cd,考虑了垃圾堆的水动力演变。宏观和微观观察,晶粒尺寸,凝聚粒子,密度,水力传导率,还有Pb,Zn,从两个废物堆场的八个钻芯和主成分进行的Cd浓度和层次聚类分析表明,废物堆的物理性质密切控制了TTE的流动性和从尾矿的迁移。获得的数据还表明,上碳酸盐层首先受到风和降雨的侵蚀。然后,不渗透的碳酸盐地壳的形成限制了铅,Zn,和Cd释放。然而,下层的水动力演化是不同的。由于高堆废物沉积物的重量意味着岩石静压力(Pl),DII和DIII垃圾场的地静力比(λ=Pf/Pl)分别优于0.29和0.26。因此,超压流体增加了矿物溶解,包括金属的硫化物和碳酸盐,水力压裂提高了移动TTE和迁移指数的百分比。根据次生孔隙和裂缝体积,受污染的流体通过重复的(多相)流体脉动逐渐被引导到压力不足的驳船(倾倒边缘)。