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The high level of sodium in red mud (RM) is one of the main issues hindering its incorporation as a raw material for construction and building materials. This paper presents a few studies on building materials developed using more than 70% w/w RM content. A proposed industrial process flowchart together with capital (CAPEX) and operational expenditure (OPEX) for a large‐scale plant are presented here. It was estimated that the cost of processing 75 Mton of RM, over a period of 25 years, was US$ 17/ton, including CAPEX + OPEX. The products comprised pellets composed of RM and clay subjected to 1200°C in a straight‐grate kiln. The pellets can be used as road gravel, coarse aggregate in concrete, or converted into supplementary cement material for Portland cement. The collaboration of the construction and building material industry with the alumina industry will be beneficial to mitigate the environmental impacts of RM.

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.

A crescente geracao de residuos resulta em uma intensa preocupacao quanto a disposicao final destes materiais. Os advindos da industria de cerâmica vermelha despertaram o interesse para o uso em argamassas e concretos, pois, devido a sua composicao, sao capazes de gerar reacao pozolânica. Neste trabalho, foram realizados testes com os residuos coletados em tres empresas (A, B e C) da regiao sul de Santa Catarina, caracterizando- os e, posteriormente, produzindo argamassas com 10% de substituicao e adicao em relacao a massa de cimento. Partindo de um planejamento experimental de misturas, verificou-se a influencia de cada residuo na resistencia a compressao e tracao das argamassas. Embora as analises quimicas e os difratogramas de raios X tenham demonstrado caracteristicas semelhantes para ambos os residuos, as amostras contendo apenas o residuo C conciliaram maiores valores de resistencia a compressao e tracao. Apesar das diferencas observadas nas propriedades mecânicas entre as misturas, a analise estatistica do planejamento experimental comprovou que, ao trabalhar com um traco de 10%, as resistencias nao sao significativamente alteradas pela composicao da adicao/substituicao. Exceto para as composicoes com 10% de adicao, nao houve evidencias estatisticas de que as propriedades mecânicas das misturas que combinam os piores resultados de resistencia a compressao e tracao sao diferentes da amostra de referencia. Os resultados indicam que parte do cimento pode ser substituida pelo residuo de cerâmica vermelha sem prejuizos ao desemprenho mecânico da argamassa e que, ao se trabalhar com adicoes, ha um aumento da resistencia a compressao, viabilizando sua incorporacao e criando um meio para a reciclagem deste material. Palavras-chave: Residuo de cerâmica vermelha. Argamassa. Resistencia mecânica

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.