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Pyrite is part of the tailings from coal mining and presents a great valorization potential technological, economic and environmental in the production of nanoparticles. In this work, pyrite from coal mining was subjected to high-energy milling and the particle size reduction, electrical and optical properties were evaluated. With the milling parameters used, the apparent size of the crystallites was reduced from 34.7 nm to 23.8 nm, resulting in highly unstable particles and charge carriers with low mobility. Due to this instability, submicron particles were observed, in the range of 300–500 nm, with a hydrodynamic diameter of 1257 ± 36 nm. The processed pyrite showed good visible light absorption and an indirect band gap of 1.51 eV.

The increase in waste generation in the textile and clothing industry is a reflection of population growth. In Brazil, only 20% of this waste is reused. The construction industry is one of the sectors that are able to absorb solid waste from various industrial activities, seeking alternatives for use and for waste valorization. Correspondingly, in this work, coating mortars were produced with the incorporation of fabric shavings (cement: hydraulic lime: sand at a ratio of 1:1:6 by mass), and evaluated them as reinforcement or thermal insulation materials. The waste was shredded manually to emulate the fibers that exist in the market. To analyze the influence of waste on the coating mortars properties, a 32 factorial design was performed, wherein the yarn content varied (at 1, 2, and 3% in relation to the binder mass) and the length varied at 1, 2, and 3 cm. The mortars that contained the yarns were experimentally evaluated based on flexural tensile strength and tensile adhesion strength tests. The best composition (yarn content of 3% and length of 3 cm) was subjected to a) thermal tests at 40 °C and 60 °C, b) mechanical, and c) physical tests, and their outcomes were compared with those of the reference sample (without waste). When waste was introduced in the mortars, the water/binder ratio increased to maintain the same consistency index. In the adhesion test, the mortars with waste adhered to the substrate and reached the minimum strength value required by the technical standards of 0.30 MPa. The flexural tensile strength was also higher than the established 1.0 MPa. With the exception of tensile adhesion strength, the mechanical strength of the mortar with the fabric yarns was less than that of the reference mortar. The mortar with the added waste yielded a satisfactory performance in thermal tests at 60 °C.