Heavy metal release from phosphorite tailings into seawater: a simulated laboratory study

A number of laboratory experiments were carried out to assess the desorption of trace metals from sedimentary phosphorite samples into artificial seawater. Shaking and percolation experiments have been performed on phospho- rite samples from the Cd-rich phosphorite deposits of Hahoto´e]Kpogam´e Togo, West Africa. using artificial seawater in the ratio 1:10. The results show that elevated concentrations of trace elements Cd 17]256 mgrl., Ni 12]193 mgrl., Zn 21]200 mgrl. and major elements Al 6]1915 mgrl. and Fe 30]1264 mgrl. are released into seawater by desorption processes. Maxima of trace metals with high mobility are reached within 4 h indicating the fast desorption kinetics in seawater. Thus, the direct disposal of potentially toxic metal-rich mine tailings may lead to regional coastal water pollution.