AMD-Derived Ferric Chloride Turns Mine Waste Into Clean Water
Researchers from Heriot-Watt University and the University of South Africa have developed a process that turns acid mine drainage (AMD) into a useful chemical for drinking water treatment.
AMD, a toxic wastewater formed when mining exposes certain minerals to air and water, is known for contaminating rivers and groundwater with metals such as iron, aluminium, and manganese. Its impacts can render water undrinkable, destroy ecosystems, and even corrode infrastructure.
The joint research team successfully extracted ferric iron (Fe(III)) from AMD and converted it to ferric chloride, a common coagulant used in water treatment facilities. Based on the tests done, removal rates of over 99% for aluminium, chromium, iron, and other contaminants from river water were achieved. Even better, the treated water met South Africa’s standards for drinking water.
University of South Africa Professor Vhahangwele Masindi said:
“Active and derelict coal and gold mines in South Africa discharge close to 400 million litres of acid mine drainage per day, and this demonstrates the viability of using this wastewater stream as a secondary mine for valuable minerals. This approach supports the circular economy by turning waste into a product with real value. It also helps reduce the environmental footprint of mining operations.”
To produce the ferric chloride, the team used magnesium oxide nanoparticles derived from calcined cryptocrystalline magnesite to precipitate iron from the AMD, which was then reacted with hydrochloric acid.
Dr Spyros Foteinis highlighted the broader potential of the method, stating:
“We’re demonstrating that even highly contaminated mine water can be cleaned up. This could be a low-energy and low-carbon practical solution to a problem that blights communities around the world and has lasting health, ecological and economic impact. The scaling up of this sustainable technology can underpin global efforts to manage industrial waste more sustainably and advance the global effort for clean water and sanitation for all.”
Looking ahead, the researchers aim to pilot the technology in water-scarce rural and peri-urban communities. Mamile Belina Mahlohla added:
“Climate change is exacerbating water scarcity pressures and creates new challenges that the water sector needs to address sustainably. This technology can be part of a portfolio approach. We’re also working on different methods of recovering nutrients and clean water from municipal wastewater.”
Read the full article here to learn more about the AMD-derived ferric chloride.
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