Mitigating soil contamination at abandoned Moroccan mine sites
Abandoned mines are putting people and ecosystems at risk in Morocco
Since the advent of modern excavation techniques in the 1920s, Morocco has become a vibrant mining hub. To this day, the exploitation of the country’s rich mineral deposits has been a key driver of economic growth, with approximately 240 mine sites currently in operation.
Over the years, however, a number of mines have closed. These mines were often vacated without proper decommissioning due to the absence of a legal framework requiring mine owners to decontaminate or rehabilitate sites after closure. As a result, Morocco is home to more than 200 abandoned mines that pose significant environmental and health concerns to surrounding communities. With no post-closure plan in place, abandoned mine sites can be toxic.
Supporting collaborative research for innovative solutions
Research Chairs led by Rachid Hakkou at Cadi Ayyad University in Marrakesh and by Mostafa Benzaazoua at the Université du Québec en Abitibi-Témiscamingue joined forces in 2009 to find innovative solutions to the challenges presented by Morocco’s abandoned mines.
This collaboration between Canadian and Moroccan researchers, made possible by the International Research Chairs Initiative, a collaboration between IDRC and the Canada Research Chairs Program, allowed researchers to pool their unique expertise to develop novel and cost-effective techniques to contain acid mine drainage and to use mine waste as building materials. Hakkou and Benzaazoua were also able to deepen their association and develop partnerships with companies and researchers in Canada, Morocco, and internationally.
Among their activities, the research teams developed a comprehensive database of abandoned mine sites, analyzing their geochemistry and estimating their environmental impact. This database made it possible to locate mines generating acidic or non-acidic waste, and to identify their containment and restoration challenges.
Store-and-release covers to prevent acid mine drainage
The strategies commonly used in temperate climates to mitigate acid mine drainage involve creating tailing ponds (i.e., sealing the mine tailings — the ore waste of mines — and covering them with water) to prevent oxidation, or removing sulfurs with flotation techniques.
In semi-arid climates, however, these methods are impractical and costly. Through experimentation, the research team identified the potential of using the waste from one mine to neutralize another. In Kettara, researchers took advantage of the hot weather and abundance of carbon-rich phosphate mine waste from the neighboring Youssoufia mine to create a shield that retains, neutralizes, and then releases water through evaporation. This“store-and-release cover” prevents rainwater from oxidizing the mine tailings and releasing acids that contaminate soil and groundwater.
The Kettara mine site is an abandoned pyrrhotite ore mine located 30km northwest of Marrakesh. The site contains more than 3 million tons of mine tailings that continue to generate acid mine drainage three decades after closure.
Numerous trials confirmed the effectiveness of the store-and-release design, even during extreme rainfall. The team then scaled up the tests to create a store-and-release cover over the entire mine site, effectively making Kettara the first contained abandoned mine site in North and West Africa.
Recycling non-acidic mine waste
The idea of using one mine’s waste to neutralize another’s informed subsequent research into the potential uses of non-acidic mine waste. Mine tailings with stable properties have shown promise for various construction applications.
The Jerada mine, for example, has a 20 metric ton deposit of coal and fly ash. Situated in the country’s northeast, a mine waste mountain that backdrops the town of 45,000 people may well fuel another industry. The research team is testing the development of lightweight ceramics by mixing the coal tailings with local clay to compete with commercial products.
Researchers have manufactured mortar, concrete, artificial stones, and bricks with recovered residual coal and fly ash, which meet the international standards for mechanical and durability properties as well as environmental performance. If successful, innovation in mine waste recycling could provide marginalized communities with meaningful employment while addressing the environmental and health impacts of mining debris.
Moving forward: Sharing lessons from the Kettara restoration experience
These reclamation and recycling research results have attracted attention from notable companies and regional governments, with large mining corporations regularly requesting advice and expertise on mine waste management. For example, principal investigators Benzaazoua and Hakkou had a key opportunity to influence practice when they were asked to prepare a course on post-mining management for the International Symposium on Technology and Innovation, organized by one of Morocco’s largest mining companies, the OCP Group. The research team also organized a workshop on sustainable mining and development, sharing their results and practices with mining groups across francophone Africa.
With a growing reputation among policy circles for generating concrete and affordable solutions to Morocco’s environmental challenges, the two researchers received the prestigious Hassan II Prize for the Environment, awarded by Morocco’s Ministry of Mines, Water and Environment in August 2016.
While research, development, and knowledge-sharing are ongoing, the outcomes to date have signaled the strong potential for scaling these practices in semi-arid regions where abandoned mines negatively impact the environment.