Chemical containment of mine waste

Abstract

Abstract The safe disposal of material considered hazardous is a natural part of good housekeeping for any industrial development. This is particularly so for the mining industry which has historically not always been so well managed in this aspect and as such has a high political profile today. Typical problems associated with mineral processing and mine waste are: • poor water quality, through the release of sulphate, acidic waters, metals, metalloids and other undesirable substances • poor air quality, through the release of mineral dust and gases such as SO 2 , As 2 O 3 , Hg vapour and CO 2 amongst others • contamination of land by the above with elevated levels of metals, sulphate and metalloids. When the impact has been allowed to occur, control can be difficult and remediation costly. Consequently great efforts have been made over the last ten to fifteen years in understanding the nature of the potential pollutants, their pathways, environmental tolerances and solutions to their impact either by ‘dilute and disperse’ methods, recovery or containment. In discussing the chemical containment of mining waste three broad categories can be defined: source control, migration control and dispersion control. Source control refers to measures employed to prevent the release of contaminants from solid phases. Migration controls restrict the interaction between environmental agents (principally water and humid air) and the deleterious element solid hosts. Dispersion control involves the collection and treatment of contaminated material such that they can be dispersed into the environment without significant impact. This last option, although the most common practice is also the most expensive and also may be required long term.