Suspension and infiltration of copper concentrate in a gravel bed: a flume study to evaluate the fate of a potential spi
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ORIGINAL ARTICLE
Suspension and infiltration of copper concentrate in a gravel bed: a flume study to evaluate the fate of a potential spill in a Chilean river N. Bustamante‑Penagos1,2 · Y. Niño1,2 Received: 14 March 2019 / Accepted: 9 November 2020 / Published online: 23 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This paper shows the advances of an experimental study of the spill of copper concentrate into immobile gravel beds. The purposes of this research are to identify the dynamics of the copper concentrate as it spills in gravel bed rivers due to mining pipeline accidents, and to quantify loads of transport in suspension and bed infiltration experimentally. The sedimentation process is generated downstream of the spill, inducing the infiltration into the bed. We have found two types of infiltration: unimpeded static percolation, when the pore size is larger than the size of copper concentrate into the substrate, or bridging layer, when the size of copper concentrate is larger than the pores in the substrate. For large fluvial sediments, d90s ∕d50c > 47 , the infiltration of the copper concentrate reaches a state of unimpeded static percolation. Moreover, when the size of the granular material is small, d90s ∕d50c < 28 , the bridge layer avoid free infiltration of the copper concentrate. The maximum length of the bed on which we could make measurements is limited by the dimensions of the flume. About 50% by weight of the copper concentrate infiltrates in to the bed within a distance equal to 100 flow depths, downstream from the point where the spill was generated. Due to its high density, ultimately, the copper concentrate must completely infiltrate into the bed. Keywords Unimpeded static percolation · Bridging · Copper concentrate · Suspension load · Mining accident
Introduction Large amounts of fine sediment may be introduced into gravel bed rivers by erosion and anthropogenic changes, such as changes in land use in the watershed, mining accidents (ore concentrate or tailings), dredged material disposal from mining activities, or natural changes as erosion in the basin (Lisle 1989; Parker 1996; Macklin 2006). Pollution in gravel-bed rivers with fine materials has environmental effects; it may reduce hyporheic exchange, affecting oxygenation of fish eggs, macro-invertebrate survivorship, nutrient cycling, and pollutant retention (Beschta and Jackson 1979; Diplas and Parker 1985; Iseya and Ikeda 1987; Lisle 1989; Nuñez-González 2016, and others). When fine material comes from mining, the problem is exacerbated
* N. Bustamante‑Penagos [email protected] 1
Department of Civil Engineering, Universidad de Chile, Blanco Encalada 2002, Santiago, Chile
Advanced Mining Technology Center, Universidad de Chile, Tupper 2007, Santiago, Chile
2
because those materials have heavy metals that may reside in the substrate for a long time (Byrne et al. 2015). Additionally, fine sediment in the gravel-bed substrate can change in the river processes, hydraulic
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