Mining activities pose a risk to the environment. After valuable metals are extracted from ore, often involving the use of chemicals, millions of cubic metres of contaminated waste rock remains, which is deposited in mine tailings. These tailings cause numerous environmental problems, including airborne dust particles, water pollution, landslides, and dam failures, as exemplified by the infamous incident at Vale’s Brumadinho site in Brazil in 2019.
Kazakhstan, a resource-rich country in Central Asia, has adopted a scientific approach to mitigating the environmental damage caused by mine tailings. The Sustainable Kazakhstan Research Institute (SKRI) has developed a technology for creating a vegetative barrier to capture harmful particles from the air (“phytocapture”) near mining facilities. Utilising ENVI-met software and a powerful computer, the institute conducted 3D modelling and calculated that the planting of trees and shrubs, if properly planned, can reduce air pollution around these facilities by up to 40%.
SKRI has gone beyond scientific research, however, having implemented its phytocapture technology in practice at the Altynalmas gold mining company in Kazakhstan. Near the company’s Aksu mine, SKRI staff planted rows of silverberry shrubs, which can grow up to 1.5 metres in height and effectively capture large dust particles. A second perimeter was planted with rows of maples and elms, which, thanks to their height and dense canopies, are effective at capturing fine dust particles carried by the wind. As the trees grow, this project is moving closer to achieving the targeted 40% reduction in air pollution.
SKRI initiated a similar project this year at RG Gold, another Kazakhstani gold mining company, which is co-owned by American private equity firm Resource Capital Funds. Through the project, the SKRI team aims to plant thousands of trees and shrubs. The research institute considers improving the environmental situation in Kazakhstan and protecting the health of the people living near mining facilities to be of paramount importance.
According to the United Nations, air pollution affects 99% of the world’s population and leads to 6.7 million premature deaths annually. With each breath, people inhale tiny particles that can harm the lungs and lead to cardiovascular problems. Among these particles, the most dangerous are fine solid particles with a diameter of less than 2.5 microns (PM 2.5) – precisely the type found in the air near mine tailings.
In May, the United Nations Economic Commission for Europe (UNECE, one of five regional commissions within the UN, which brings together 56 countries) held a regional conference on the Convention on Mine Tailings Safety and Industrial Accidents. During the conference, the solutions developed by SKRI were presented as advanced practices for ensuring the safety of tailings.
Considering the industry’s needs, SKRI has also begun developing two major nature-based solutions for reducing water pollution from mine wastewater. One involves planting trees in special “wells” made of impermeable materials, allowing the root system to absorb pollutants from deep groundwater layers in the soil.
The other solution involves placing special mats made of biochar and peat at the bottom of channels or streams to absorb pollutants. The Dutch company Tauw Engineering has laid such mats at the bottom of a contaminated canal near an old asphalt plant in Ghent, Belgium.
SKRI, in collaboration with Tauw, is now conducting trials of these technologies in Kazakhstan and at the mine tailings of the Ak-Tuz rare-earth mine in neighbouring Kyrgyzstan.
* Dr Brendan Duprey is Director of the Sustainable Kazakhstan Research Institute, Narxoz University