To mitigate this problem several strategies are currently being employed and tested by the mining industry including the subaqueous disposal of sulphide-rich waste rock.
Subaqueous disposal has a number of features that make it attractive as a long-term storage option.
However, the secondary mineral assemblages that accumulate during subaerial exposure could have a profound influence on the geochemical behaviour of the waste when submerged, such that deleterious effects on water quality may result. In order to assess adequately the environmental implications of placing oxidized waste rock underwater, techniques must be developed to allow proponents and government agencies to evaluate scientifically, and ultimately predict, the potential water quality impacts of this waste rock management strategy. The ultimate objective of this project was to design a laboratory test protocol that could be used to quantify the chemical stability of waste rock oxidation products in a range of subaqueous environments. To this objective, the report first examines the mechanisms that control the formation and stability of secondary minerals in waste rock dumps, identifies the minerals that may be present in the dumps and evaluates their subsequent stability in a subaqueous setting. Second, the report examines available laboratory methods and their applicability to assessing metal release from oxidized waste rock.