Concerned Citizens of South Africa
Case Study: Water quality in gold mining operations in the Witwatersrand Basin, South Africa
1. The Study
The gold mining done in the Central Rand field in the Witwatersrand Basin is extremely valuable. Despite this, the footprints left from the mining has led to severe water pollution to the water system surrounding the mines, effecting the citizens of South Africa's health and economy. This water pollution is a result of AMD, acid mine draining. In this case study, column leaching experiments are conducted to replicate the leaching process that occurs in the remaining mining storage facilities. They analyze the chemical data gathered to figure out the potential pollution threat to surface and ground water systems.
2. Procedure
Oxidized layers on the tailings were scrapped off and measurements of pH were taken. The material was packed into column and water was filled into the pore spaces of the material. The study looked at the measured volume of water needed to create a slush using the tailing runoff.
3. The Results
Results were 600 ml of pore volume was found on average for the columns. The leaching was done at a pH of 3 and a pH of 7. pH 3 was one group to simulate the acidity of plume leaching, while the latter pH was used for water sprayed in a jet technique. The end pH was 7.8 for the recorded tailings. This was due to the addition of lime during gold extraction in the mines.
Further experiments need to be conducted in regard to the complex interaction between the solids and liquids coming from the tailings.
Hlanganani Tutu (2012). Mining and Water Pollution, Water Quality Monitoring and Assessment, Dr. Voudouris (Ed.), ISBN: 978-953-51-0486-5, InTech, Available from: http://www.intechopen.com/books/water-qualitymonitoring-and-assessment/mining-and-water-pollution
4. Solutions
Ways to eliminate AMD such as liming tend to fall short due to the lack of a systematical ratio between the sulphidic composition to the amount of lime used. Solutions implemented alongside liming will be more effective, such as efflorescent salt barriers, as they can store a high capacity of pollutants and allow cleaner water to flow into natural streams. Other reactive barriers can be included for shallow plumes, trapping the pollutants from the water. These reactive barriers can be constructed out of clay, concrete, or cost-effective materials that have the capacity to store pollutants.