As Rwanda’s mining sector expands, operators are intensifying efforts to manage mineral tailings more effectively, both protecting the environment and unlocking additional economic value.
In 2025, exports of Rwanda’s 3Ts — tin, tungsten, and tantalum — grew by 46.2 percent, according to the Ministry of Finance and Economic Planning. But processing these minerals leaves behind tailings: crushed rock, water, and leftover chemicals. Mishandled, these byproducts can create serious environmental hazards.
In the past, tailings were often left unattended or washed into rivers and nearby wetlands, causing pollution and environmental degradation. But that is increasingly a thing of the past.
In an interview with The New Times, Innocent Kagenga, the Chairperson of Rwanda Mining Association, emphasized that tailings must be carefully managed to prevent them from being carried into rivers by heavy rains or floods.
"Every company has its own tailings management plan to recycle and reprocess tailings,” he said, adding that, often, these tailings still contain valuable mineral residues that were not fully extracted during initial processing.
Through reprocessing methods such as shaking tables and crushers, companies filter out any remaining mineral content. What remains after that can still be repurposed. For example, Kagenga added, sand separated during mineral processing can produce kaolin, a key raw material used in paint manufacturing, as well as construction materials, among others.
Kagenga noted that in the past, more than 60 percent of valuable minerals could go unnoticed and be lost in tailings. Today, miners increasingly recognize their economic value. However, access to modern equipment remains a challenge. While some companies have upgraded their machinery, others are still in transition.
Additionally, Rwanda’s hilly terrain further complicates logistics. Sometimes, transporting heavy processing equipment to remote mining sites can be difficult. As a result, he said, some companies stockpile tailings while waiting to acquire the technology needed for reprocessing.
How tailings are stored
According to Berthe Rutagambwa, the Environmental and Sustainability Coordinator at Rwanda Mining Association, most mining in the country is underground. Once the main mineral is excavated, the remaining material is classified as tailings.
ALSO READ: Mining: High tin prices 'may lift investor interest in Rwanda'
At many sites, tailings are deposited in Tailings Storage Facilities (TSFs), designated containment areas often designed with drainage systems at the bottom. These facilities allow water to settle while solid particles remain contained.
"We load tailings into trucks and transport them to storage facilities where they wait to be processed,” Rutagambwa explained.
At sites with processing capacity, tailings are reprocessed using shaking tables to ensure that no core mineral is left behind.
Rutagambwa explained that not all mining sites have on-site processing plants. In such cases, tailings are stored and covered to prevent rainwater from washing them away.
ALSO READ: Critical minerals take centre stage at Rwanda Mining Week 2025
If heavy rainfall causes overflow, many sites use settling ponds to capture runoff. The sediment settles at the bottom, awaiting reprocessing, while water is often treated and recycled back into operations.
What would happen if tailings were not contained?
Rutagambwa warned that unmanaged overflow could affect swamps and rivers. Tailings water may contain iron, heavy metals, or other substances that can reduce oxygen levels and threaten aquatic life.
"In rivers and wetlands, aquatic species can suffocate if exposed to heavy metals,” she said.
So far, no fatal environmental incidents linked to tailings have been reported, thanks in part to collaboration between mining operators and Rwanda Environment Management Authority (REMA).
Still, Rutagambwa acknowledged that some smaller sites lack fully engineered TSFs, increasing vulnerability to soil erosion and landslides, especially during heavy rains.
Untapped opportunities
Beyond re-extracting core minerals, tailings present additional industrial opportunities that remain largely unexplored.
"There are many by-products in tailings,” Rutagambwa said. "But processing capacity is still limited.”
Most reprocessing efforts currently focus solely on recovering primary minerals rather than developing secondary industrial products, she said.
"Reprocessing is not yet advanced. Most sites store tailings and wait until they can afford processing plants.”
Persisting challenges
Rutagambwa pointed out power supply as one of the most pressing issues. Many mining sites are located in remote areas with limited electricity access. Solar energy has been considered, but underground tunnel operations and processing plants require stable grid electricity.
Infrastructure is another bottleneck, especially as most mine sites are in what she described as isolated places. Poor road access can make it difficult to transport tailings to centralized processing plants, especially when they are in different districts.
To address this, efforts are underway to explore shared processing facilities for mining sites located in proximity.
What is being done?
Explaining Rwanda Mining Association’s efforts to ensure proper tailing management, compliance, and standardized mining practice, Kagenga noted that they have designated two employees in every province, including an environment officer and a mining engineer.
According to an official from Rwanda Mines, Petroleum, and Gas Board (RMB), the government is collaborating with various institutions to address these concerns. He pointed to partnerships with the Ministry of Infrastructure to address infrastructure issues, including connecting remote mining facilities to a reliable power grid.
He also cited a partnership with REMCO, a company specializing in designing equipment, to supply the local mining operators with the required manufacturing inputs.