Assessment of Pollution Potential of Cyanide-Bearing Tailings Dam *

Abstract

This study ascertained the types of chemical species that are formed in tailings material of gold leaching plants and assessed their short and long term pollution potential capabilities. The results revealed that chemical, biochemical and geochemical reactions were occurring in the tailings material; producing complexed cyanides, bicarbonates and nitrates which accumulate with depth in the tailings material while ammonium, carbonate and sulphate ions decreased with depth. Heavy metal accumulation particularly Mn, Pb, Zn Cu, Fe were also observed to increase with depth. It was concluded that the cyanide bearing tailings material has short term pollution potential of free cyanides, ammonium ions, sulphates ions and a long term risk of, complexed cyanide, nitrate and increase in water hardness due to bicarbonate ion. Heavy metal pollution and a decrease in pH are also possible.