Turning tailings into traction how iron ore sand could pave a stronger safer and more sustainable future for mine haul roads

A waste stream from iron ore processing is proving it can outperform conventional materials in building mine haul roads and deliver major environmental gains.

At the Life of Mine | Mine Waste and Tailings Conference 2025 in Brisbane, Dr Gino Omar Calderon Vizcarra, specialist geotechnical engineer at Vale S.A., presented the paper “Utilising Iron Ore-sand for Sustainable Mine Haul Road Construction”, co-authored with Kathy Tehrani, Juliana Segura-Salazar and Claudio Andrade.

The research examined whether iron ore-sand – a byproduct from Vale’s operations in Brazil’s Iron Quadrangle – could be repurposed as an embankment material for mine haul roads, replacing traditional sources such as quarried natural sand or local residual soils.

Addressing three challenges at once

According to Gino, the motivation for the project lies in three interconnected industry challenges. First, the mining sector continues to generate vast volumes of tailings, creating long-term storage and safety risks. Second, tailings storage facilities (TSFs) remain high-consequence infrastructure, where stability issues can lead to significant environmental and social impacts. Third, there is growing global pressure on natural sand resources, which are under strain from construction and industrial demand.

“Our approach is about applying circular economy principles,” he told delegates. “We want to reduce iron ore tailings volumes while creating a high-quality construction material – turning a waste stream into a resource.”

From process plant to road base

Ore-sand is produced during iron ore beneficiation, which involves processes such as gravity separation, magnetic separation, thickening, flotation and classification. In addition to producing marketable iron ore products such as sinter feed and pellet feed, the process yields a granular byproduct – the iron ore-sand.

Instead of stockpiling or disposing of this material in a TSF, the Vale team set out to test whether its properties made it suitable for use in high-load embankments. The research was conducted in partnership with the University of Queensland, combining environmental and geotechnical characterisation.

Safe and stable

The environmental assessment confirmed that the ore-sand is predominantly silica (around 90%), with approximately 9% iron oxides and a minor fraction of other minerals. It has a neutral pH, low salinity, and trace metal concentrations below threshold levels. “It’s safe for reuse – non-toxic, and compliant with environmental guidelines,” Gino emphasised.

Physically, the team compared ore-sand to local residual soil. Gradation curves showed that the residual soil contained 60% fines and displayed plasticity, whereas the ore-sand had 28% fines and no plasticity. Compaction tests revealed that the ore-sand achieved a lower void ratio than the residual soil, indicating denser packing potential under compaction.

Outperforming residual soil under load

Triaxial shear tests indicated that ore-sand had a higher shear strength than residual soil, both under drained and undrained conditions. The critical state line analysis showed lower deformability for ore-sand, meaning it would be less prone to settlement under repeated heavy truck loads.

These lab results were then applied in a slope stability model of a mine haul road cross-section. Both designs used identical foundations, but one embankment was built with residual soil and the other with ore-sand. The simulated heavy vehicle loading conditions revealed that the ore-sand embankment achieved a higher factor of safety than its residual soil counterpart.

“In heavy-haul environments, that extra margin of stability is critical,” Gino noted. “It’s not just about meeting a minimum factor of safety – it’s about building resilience into the road structure.”

Environmental and economic upside

The benefits go beyond geotechnical performance. Using ore-sand reduces the amount of tailings stored in TSFs, lowering both storage costs and the potential consequences of failure. It also reduces demand for natural sand, helping to conserve ecosystems affected by quarrying.

On the economic side, the material’s on-site availability eliminates the need for long-distance haulage of construction aggregates, cutting transport costs and carbon emissions. “You’re effectively producing your own construction material within the mine boundary,” Gino said. “That’s a win for safety, sustainability and the bottom line.”

Pathway to adoption

While the research confirms technical feasibility, Gino and his co-authors recommend further studies to evaluate brittleness under field conditions, optimise mix designs, and fine-tune construction methods for different climates and geologies. Pilot-scale field trials are seen as the logical next step to validate performance in live mine haul road applications.

“Our data shows that iron ore-sand is a viable, high-performance and environmentally responsible option,” Gino concluded. “It’s an opportunity for mining companies to rethink how they manage tailings and source construction materials – and to close the loop on a major waste stream.”

Pictured is Dr Gino Omar Calderon Vizcarra presenting his research on using iron ore-sand for sustainable mine haul road construction at the Life of Mine | Mine Waste and Tailings Conference 2025. Photo: Jamie Wade.