Eduardo Junca

Briquettes represent a sustainable and viable approach for the reutilization of solid urban and industrial waste. Their incorporation into wood‐based briquettes aims to generate thermal energy through combustion, enabling application in industrial thermal systems already equipped with flue‐gas emission control. In this study, briquette compositions were developed using a mixture of three waste materials: wood, charcoal fines, and plastic packaging. The thermal and physical properties of the resulting briquettes were subsequently analyzed. The results indicate that the inclusion of charcoal fines impairs briquette compaction due to the absence of binding agents. In contrast, the addition of plastic packaging waste, which melts at the processing temperature, promotes the formation of heterogeneous agglomerates within the briquette structure. Thermal analysis revealed that both charcoal and plastic residues exhibit lower ash content compared to wood. The calculated activation energy ranged from 200.6 to 216.0 kJ/mol for wood, 136.5 to 174.7 kJ/mol for charcoal, and 338.9 to 356.7 kJ/mol for plastic. Among the samples analyzed, the briquette composed of 80% wood, 10% charcoal, and 10% plastic showed the highest calorific value. The incorporation of charcoal and plastic waste significantly enhanced the energy content of the briquettes, demonstrating the potential of this composite formulation for efficient energy recovery.

This study evaluates the characteristics and environmental behavior of river sediments impacted by coal mining in the southern coal region of Santa Catarina, Brazil. Sediments accumulated in mining-affected rivers represent an environmental liability due to the presence of potentially toxic elements and their limited management options. In this context, ceramization is investigated as an alternative strategy for reducing contaminant mobility through thermal treatment of sediments collected at four sampling points (PU1–PU4) along the Urussanga River. Initially, leaching and solubilization tests were performed to assess the mobility of chemical elements, and the raw sediments were further characterized by chemical, mineralogical, and thermal analyses. Subsequently, ceramic specimens were produced from the sediments and subjected to thermal treatment at 1100 °C. After firing, the specimens were re-evaluated through leaching and solubilization assays to verify changes in contaminant mobility after the ceramization process. The results showed that raw sediments exhibited aluminum, iron, and manganese concentrations in the solubilized extract that exceeded regulatory thresholds, particularly for iron, which reached up to 21.91 mg/L. After thermal treatment, a substantial reduction in the solubility of these elements was observed, with concentrations falling below the established limits at all sampling points. This reduction in mobility is likely associated with physicochemical transformations occurring during firing, including matrix densification and the incorporation of elements into less soluble phases, as reported in previous ceramic processing studies. Overall, the findings demonstrate that ceramization represents a promising strategy for reducing contaminant mobility in coal mining-impacted river sediments, offering a viable and environmentally friendly alternative for sediment management and valorization.

Uso, distribuição e reprodução em qualquer meio, sem restrições desde que o trabalho original seja corretamente citado. a Resumo A resistência química de polímeros termoplásticos é fundamental para garantir sua durabilidade em aplicações industriais. Neste estudo, avaliou-se o comportamento de PP, EVA e PEBD após exposição a acetona, pentano, hidróxido de sódio, ácido acético e ácido sulfúrico por 24 e 48 horas. Corpos de prova moldados por injeção (ASTM D638-03) foram submetidos a ensaios de tração, com análise estatística por ANOVA, teste t e Tukey (α = 0,05). O EVA apresentou maior sensibilidade, com reduções marcantes no módulo elástico e na tensão máxima, especialmente para o pentano, que diminuiu a tensão de 23,02 MPa (puro) para 11,68 MPa (24 h) e o módulo de 22,96 MPa para 9,52 MPa (24 h). O PEBD e o PP mostraram resistência moderada, embora mais afetados por solventes apolares; no PEBD, o módulo caiu de 40,71 MPa para 21 MPa (pentano), enquanto no PP a redução foi menos intensa, de 596,61 para 445,68 MPa. As diferenças entre 24 e 48 horas foram pequenas, sugerindo que a degradação mecânica ocorre majoritariamente nas primeiras 24 horas. Os resultados reforçam a importância da composição polimérica, da polaridade do solvente e do tempo de exposição no projeto de materiais para ambientes quimicamente agressivos. Palavras-chave: Degradação química; Propriedades mecânicas; Análise estatística. Statistical analysis of the tensile strength mechanical properties of thermoplastic polymers (EVA, LDPE, PP

The aim of this study was to initiate the development of a route for the extraction of niobium oxide from columbite ore using sodium carbonate and boric acid. Initially, the columbite ore was characterized. Eight formulations were prepared to investigate the proportion of sodium carbonate to boric acid. The fusions were carried out at 900 °C for 60 min. Afterwards, magnetic separation was performed to remove the iron present in the formulations. From the non-magnetic fraction, water leaching was conducted to investigate the effects of temperature, time, and solid-to-liquid ratio. Finally, the product obtained from water leaching was calcined to obtain niobium oxide. The results indicated that the addition of boric acid contributed to reducing both viscosity and fusion temperature, favoring the release of niobium. The water leaching step showed an inverse dependence on the solid-to-liquid ratio, meaning that decreasing the solid content and increasing the water content favored the solubilization of niobium-containing phases. Temperature and time did not have a statistically significant effect on the leaching process. At the end of the route, niobium oxide was obtained as the final product, confirmed by X-ray diffraction and scanning electron microscopy.

Foundry slag has different characteristics from blast furnace slag, such as its high SiO₂ content and low basicity (CaO/SiO₂ < 1), which prevent it from being used as a cementitious component. Lime slurry is a waste product with a high CaO content and can be used to increase the basicity of the mixture. The aim of this study is to obtain new supplementary, eco-cementitious material composed of foundry slag and lime sludge. The compositions were designed with binary basicity (molar ratio of CaO/SiO₂) ranging from 1.0 to 1.4. Clinker was replaced with the proposed material in the range of 6–34 wt% and the performance of the different cement compositions was tested. The results showed that replacing 20 wt% of clinker with the new eco-cementitious material with binary basicity of 1.2 resulted in cement with the same mechanical strength as the reference cement. The new material reacted with free CaO to generate additional calcium silicate hydrate. The initial setting time of the cement containing the new eco-cementitious material was 240 min, acting as hydration reaction retardant. The technical feature of the new eco-cementitious material allows the use of both wastes in cement composition, contributing to the requirements of circular economy.

One of the alternatives for reducing carbon emissions in the steel industry is the use of bio-coals. However, the use of biomass and its derivatives in steelmaking processes presents technical challenges due to their different chemical and physical characteristics to fossil fuels. In this context, this study aims to evaluate the effect of hydrochloric acid on the demineralization of eucalyptus charcoal, in order to understand its properties and potential application in the steel industry. To this end, the charcoal was subjected to a demineralization process using hydrochloric acid, varying the liquid-solid ratio (10:1 – 20:1) and molar concentration (1 - 3 M). The samples were then filtered, washed with deionized water and dried in an oven. The biochar was then characterized by determining surface area, moisture content, volatile content, ash content, fixed carbon content and kinetic analysis. The results showed that the surface area of the treated biocarbons increased by up to 438.38%, there was a reduction in the ash content of up to 91% and the activation energy of the gasification reaction varied between 54.8 and 109.9 kJ/mol.

Blast furnace slags are formed by CaO-SiO₂-Al₂O₃-MgO systems and have several physical characteristics, one of which is viscosity. Viscosity is an important variable for the operation and blast furnace performance. This work aimed to model viscosity through linear and non-linear models in order to obtain a model with precision and accuracy. The best model constructed was a non-linear model by artificial neural networks that presented 23 nodes in the first hidden layer and 24 nodes in the second hidden layer with 6 input variables and 1 output variable named ANN 23-24. ANN 23-24 obtained better statistical evaluations in relation to 11 different literature equations for predicting viscosity in CaO-SiO₂-Al₂O₃-MgO systems. ANN 23-24 was also subjected to numerical simulations in order to demonstrate the validation of the non-linear model and presented applications such as viscosity prediction, calculation of the inflection point in the viscosity curve by temperature, the construction of ternary diagrams with viscosity data, and the construction of iso-viscosity curves.

The formation of the solid phases CaS, 3CaO.SiO₂ and CaO.Al₂O₃ around the lime particle decreases the efficiency of desulfurization by the kanbara reactor (KR) process. The addition of fluxes reduces the formation of these phases. The addition of Al and Si can also have this effect, depending on the added levels. In this study, different mixtures based on CaO with different levels of fluorspar, sodalite (Nepheline Syenite), and SiO₂ and Al₂O₃ content were studied and used in the desulfurization process of hot metal. These mixtures were added to a bath of liquid hot metal at 1400 °C. All experiments were performed with mechanical agitation. Samples were taken at times of 5, 10, 15, and 20 min, and analyses were performed to evaluate the variation of sulfur over time. The Thermo‐Calc software was used to determine the formed phases, solid fraction, and liquid fraction of the different mixtures. With this data, different values of the Global Desulfurization Factor (FG_DeS) were calculated, which was developed to evaluate and predict the efficiency of hot metal desulfurizing mixtures by the KR process. The results of showed that fluorspar was more efficient than sodalite. The FG_DeS had a correlation factor (R²) above 0.9 with the desulfurization efficiency.

New materials and technologies used in construction constantly need improvements, whereby the leveraging of new raw materials for the manufacture of products already in use, such as paving, is required. Thus, this study aimed to determine the mechanical and thermal behavior of pavers containing waste glass and São Tomé stone waste to verify their potential application as cold diffraction. Thereafter, they were comminuted and added to the mixtures for making the pavers having glass waste and São Tomé stone in the range of 0-30% by weight. Mechanical compressive strength and thermal heat absorption tests were performed. Results showed that the replacement of fine aggregates with waste glass and São Tomé stone waste in pavers reached a mechanical resistance of approximately 85% and 73% of that of the reference paver, respectively. The results show that reducing the waste content of pavers can increase the mechanical strength to reach the NBR 9781/87 values. However, pavers with lower mechanical strength can be used in paving pedestrian sidewalks, where the loads are low. Pavers with 30% glass waste achieved a 5.5% reduction in the maximum temperature, which could contribute to the reduction of urban heat islands.