Chemical clogging of synthetic filters in tailings ponds caused by ferrous iron ions

Abstract

Chemical clogging of synthetic filters in tailings ponds is a common issue that threatens the safety of tailings ponds. The mechanism of the chemical clogging of synthetic filters in iron tailings is very complex due to the complicated working environment. In this study, a series of column tests was performed to study the chemical clogging of synthetic filters in tailings ponds caused by ferrous iron ions. The influence of the saturation state of synthetic filters during installation, the hydraulic gradient and the thickness of the tailings specimen on chemical clogging was examined. The morphology and distribution of clogging substances in a non-woven geotextile, a woven geotextile and a nylon net were observed. The mechanism of chemical clogging is discussed. It was found that oxygen was required for chemical clogging. The clogging substances were mainly distributed in the area of synthetic filters that contact air, and the remaining part of the synthetic filters had only limited chemical clogging or even no clogging. As chemical clogging developed, a layer of clogging film formed on the regions of the non-woven geotextile that came into contact with the holes of the perforated plate. The impervious films blocked the openings of the perforated plate in turn.