Rehabilitation prioritization of abandoned mines and its application to Nyala Magnesite Mine

• The mine site was assessed based on it associated physical and environmental hazards.
• The identified hazards were quantified to establish their seriousness.
• Hazard maps assisted in pin-pointing with accuracy hazardous sections of the mine.
• Priority of rehabilitation has to be given to extremely and moderately hazardous features of the mine.
• The hazard maps provided a more robust scientific basis for making decisions and action to be taken.

The issue of abandoned mine sites is a major environmental and social problem for the mining industry, communities and governments. Historical mine sites are characterized by significant environmental, health and safety problems. The aim of this study was to develop hazard maps that can assist in the prioritization of rehabilitation at Nyala Mine. The approach used involved site examination and characterization to establish the environmental conditions of the mine. Hazards at the mine were identified, scored, and rated using modified Historic Mine Site Scoring System. The scoring focused on source and exposure pathways. The developed hazard maps showed that the best approach of effectively reducing the physical and environmental hazards at Nyala Mine was to give priority to extremely and moderately hazardous pits; surface infrastructure and spoil dumps, and then to tailings dumps characterized with less physical hazards but extremely high environmental hazards. Pits and spoil materials which were found to be relatively less problematic in terms of physical hazards were to receive least attention. The use of this hazard-scoring and risk-ranking methodology coupled with the hazard maps would provide a more robust scientific basis for making sound decisions and prioritize actions that need to be taken to minimize or manage risks associated with various areas of the mine site.