Abstract
Massive amount of highly contaminated mining residual materials (MRM) has been left unattended and has leached heavy metals, particularly lead (Pb) and zinc (Zn) to the surrounding environments. Thus, the performance of three immobilizers, raw dolomite (RD), calcined dolomite (CD), and magnesium oxide (MO), was evaluated using batch experiments to determine their ability to immobilize Pb and Zn, leached from MRM. The addition of immobilizers increased the leachate pH and decreased the amounts of dissolved Pb and Zn to different extents. The performance of immobilizers to immobilize Pb and Zn followed the following trend: MO > CD > RD. pH played an important role in immobilizing Pb and Zn. Dolomite in RD could slightly raise the pH of the MRM leachate. Therefore, the addition of RD immobilized Pb and Zn via adsorption and co-precipitation, and up to 10% of RD addition did not reduce the concentrations of Pb and Zn to be lower than the effluent standards in Zambia. In contrast, the presence of magnesia in CD and MO significantly contributed to the rise of leachate pH to the value where it was sufficient to precipitate hydroxides of Pb and Zn and decrease their leaching concentrations below the regulated values. Even though MO outperformed CD, by considering the local availability of RD to produce CD, CD could be a potential immobilizer to be implemented in Zambia.
Highlights
Kabwe District was one of the most important mining regions in Zambia for almost a century (1902–1994)
Lead and Zn immobilized by raw dolomite (RD) were interpreted by the adsorption and co-precipitation mechanisms
Only calcined dolomite (CD) and magnesium oxide (MO) decreased the dissolved Pb and Zn concentrations to below their regulated values, in which MO had a higher performance than CD
Summary
Kabwe District was one of the most important mining regions in Zambia for almost a century (1902–1994). It was regarded as Southern Africa’s principal lead (Pb)-zinc (Zn) producer, producing. Weathering of MRM causes heavy metals to transport from the contaminated sites to the surrounding environments (groundwater, surface water, and soil) [2]. The redistribution of heavy metals through solute transport processes has been reported to be one of the most dangerous pathways, which invokes harmful effects on water sources of nearby ecosystems and health-threatening to the nearby residents [3,4,5,6,7,8,9]. The remediation of heavy metals in and around the mine is necessary
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have