Field and Economic Studies on Mine Waste: Sustainable Reuse as Aggregates for Low Traffic Pavement Structure

The phosphate extraction and processing has followed a traditional linear consumption model, where wastes are continuously produced and surface land is filled in rock piles. Thus, to promote a circular economy in a mining context, more eco-friendly and sustainable solutions at the regional level are needed. This paper deals with the potential utilization of phosphate screening waste rock 0–100 mm (SWR) as alternative aggregates for pavement applications. Detailed in situ and laboratory tests have been made for SWR characterization, and the practical modalities of implementation have been defined. The findings proved that SWR (10–100 mm) materials can be successfully used without treatment in capping layer construction for low-volume traffic pavement projects. Due to its high apatite content, the remaining fraction (0–10 mm) can be exploited to recover the residual phosphate using the processing method that is currently followed by the mining company. Furthermore, the environmental investigations showed that SWR does not present any potential contamination risk to the surrounding environment. The economic feasibility analysis confirmed the workability of SWR reuse in a radius of 100 km around their dumps due to its lower cost compared to conventional aggregates. This simple amendment may ensure a smooth transition from a current linear extractive approach to a circular economy.