Potential of iron and copper sulfide mine tailings in geopolymerization: A sustainable approach to construction materials

The mining industry has a crucial role in a country’s development, contributing significantly to both economic and technological progress. However, mining activities often leave a negative impact on ecosystems. A promising approach to mitigate these effects and enhance the sustainability of building materials is to utilize these tailings in conjunction with sustainable binders such as geopolymers. Geopolymers are alkali-activated materials that exhibit properties comparable to Ordinary Portland Cement but offer superior sustainability benefits. This study explored the incorporation of four different tailings, derived from distinct areas of the same copper and iron sulfide mine, into geopolymer. The formulations were prepared by adding 0, 10, 20, and 30 wt% of each type of tailing. The investigation included compressive strength tests, mercury intrusion porosimetry, BET surface area analysis, microstructural characterization via scanning electron microscopy, and leaching tests. The results indicated that incorporating up to 20 % by weight of mine tailings had a negligible impact on compressive strength, maintaining values between 33 and 37 MPa after 90 days of curing. Generally, the addition of tailings led to an increase in mesopores and a reduction in micropores. Furthermore, after six months of curing, the geopolymeric matrix was found to immobilize harmful elements present in the tailings, such as sulfur, copper, iron, and others. These findings suggest that utilizing mining tailings in geopolymers offer advantages in physical properties and enhancing the sustainability of building materials. Moreover, this approach provides economic value to a mining by-product that would otherwise be discarded, thereby reducing environmental contamination. • Tailings with iron sulphate are more altered by alkaline activation than iron oxide. • Geopolymers with 20 % tailings exhibited a compressive strength between 33 and 37 MPa. • Tailings led to an increase in mesopores (96 %) and specific surface area (53 m 2 /g). • Geopolymers can capture harmful elements through the exchange of sodium cations.