Transport and Fate of Cyanide in Soil : Case Study of Mooteh Valley

Abstract

Cyanide, a generic term referring to all compounds containing the cyanide group –CN, is a highly potent and fast-acting poison to humans and other living organisms when exposed to high levels. Cyanide is a widely and essential chemical used in mining and minerals processing industries and many other industries such as metal processing and production of organic chemicals. While some industrial cyanide-containing wastes are treated or recovered, there are cases such as certain gold extraction plants where wastes are released in the environment. The objective of this research is to study the transport and fate of cyanide in soil in vicinity of a specific pollution source. For the purpose of this study, Mooteh valley, in the vicinity of Mooteh gold mine and factory, in the north of Isfahan province, Iran, was investigated. In Mooteh's Plant, the cyanide-containing waste (slurry tailings) is discharged to tailings ponds and there is potential for cyanide to migrate from them. Eight boreholes with 6 m depth were dug and from every 0.5 m a soil sample was taken. Statistical analysis of the results show that soil cyanide concentration decreases with distance from the tailings ponds (as a pollution source) and increases with depth. A regression model consisting of a power term for distance and an exponential term for soil depth can appropriately predict the soil cyanide concentration in the vicinity of a pollution source. As soil depth decreases, the rate of natural cyanide fate processes considerably increases. So, soil turn over practices is recommended to improve remediation of polluted site