RESUMEN
Dispersion-hardened materials based on TiC-AlnCn are alloys with high heat resistance, strength, and durability that can be used in aircraft and rocket technology as a hard lubricant. The titanium-rich composites of the Ti-Al-C system were synthesized via the spark plasma sintering process. Composite powder with 85% of Ti, 15% of Al, and MAX-phases was processed using high-voltage electrical discharge in kerosene at a specific energy of 25 MJ kg-1 to obtain nanosized particles. This method allows us to analyze the most efficient, energy saving, and less waste-generating technological processes producing materials with improved mechanical and physical properties. An Innova test indentation machine was used to determine the hardness of the synthesized composites. The microhardness of Ti-Al-C system samples was determined as approximately 500-600 HV. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were performed to identify the hard titanium matrix reinforced by intermetallic phases and the clusters of carbides. Three types of reinforcing phases were detected existing in the composites-TiC, Al4C3, and Al3Ti, as well as a matrix consisting of α- and ß-titanium. The lattice parameters of all phases detected in the composites were calculated using Rietveld analysis. It was determined that by increasing the temperature of sintering, the amount of aluminum and carbon increases in the carbides and intermetallic phases, while the amount of titanium decreases.
RESUMEN
As the industry develops and energy demand increases, wind turbines are increasingly being used to generate electricity, resulting in an increasing number of obsolete turbine blades that need to be properly recycled or used as a secondary raw material in other industries. The authors of this work propose an innovative technology not yet studied in the literature, where the wind turbine blades are mechanically shredded and micrometric fibers are formed from the obtained powder using plasma technologies. As shown by SEM and EDS studies, the powder is composed of irregularly shaped microgranules and the carbon content in the obtained fiber is lower by up to seven times compared with the original powder. Meanwhile, the chromatographic studies show that no hazardous to the environment gases are formed during the fiber production. It is worth mentioning that this fiber formation technology can be one of the additional methods for recycling wind turbine blades, and the obtained fiber can be used as a secondary raw material in the production of catalysts, construction materials, etc.
RESUMEN
This pilot study aimed to develop a production line for SRF production from RDF by extracting prohibited materials, grinding, and drying, and the energy potential for using SRF in the cement industry as an alternative fuel was evaluated. This paper defined the main characteristics of RDF, which were obtained after the separation of the biological fraction from MSW at an MBT plant. According to its characteristics, RDF can only be used for incineration in the CPP to obtain heat and energy. The produced SRF meets the requirements for fuel from waste and can be used as an alternative fuel for clinker firing. A technological process line for SRF production from RDF has been developed by adding technical units to the existing MBT line. The SRF production line yield was calculated as 4.47 t/h. At the end of the SRF production process, the moisture content of the finished product decreased by 85%, and the volume decreased by 18%. The obtained SRF had a high calorific value, low moisture content, and a permissible value of chlorine and mercury. It was proposed that the produced SRF and sewage sludge (already used during the clinker firing process) be utilized as alternative fuels since they correspond to the oxide composition of the finished clinker in elemental and oxide composition. A calculation to assess the economic and environmental efficiency of the use of SRF in the cement kiln was conducted. The result showed that using 10% SRF as a substitute fuel for coal used in clinker roasting at 1.92 t/h would save 601.7 USD/h coal costs. This use of SRF will emit 3.7 t/h CO2 and achieve net savings of 754.7 USD/h.
Asunto(s)
Mercurio , Eliminación de Residuos , Dióxido de Carbono , Cloro , Carbón Mineral , Incineración , Lituania , Recursos Naturales , Proyectos Piloto , Aguas del Alcantarillado , Residuos Sólidos/análisisRESUMEN
In the petroleum industry during a catalytic cracking process, the used zeolitic catalyst becomes waste. This article investigated the sorption capacities of ammonium ions from aqueous solutions onto the previously mentioned zeolitic waste by batch experiments. Three types of zeolitic waste were used: unmodified zeolitic waste with two different particle size distributions and H2O2-modified zeolitic waste. Several techniques, including X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) multilayer adsorption theory measurements, and X-ray fluorescence analysis (XRF) were used to demonstrate experimentally that the zeolitic waste could be used as a sorbent for the water decontamination of NH4+ ions. The morphology of zeolitic waste investigated by scanning electron microscopy (SEM) revealed particles with a spherical shape. The nitrogen adsorption-desorption isotherms showed an isotherm mixture of types I (pure microporous) and IV (mesoporous). This suggested that the investigated zeolitic materials were mesoporous (4.84 nm) and microporous (0.852 nm), as well as containing slit/cylindric pores, according to a quench solid density functional theory (QSDFT) adsorption branch model. Zeolitic waste from the oil industry showed good NH4+ sorption properties (removal efficiency of 72%), thus becoming a potential adsorbent to be used in the treatment of contaminated aqueous effluents polluted with ammonium ions. Simultaneous waste and water decontamination can be achieved, providing a new tool and enhanced capabilities for environmental remediation.
RESUMEN
In this study, the viability to utilize the residue, obtained from a sewage sludge (SS) and biomass combustion/gasification plant (GR), in cement-based materials was analysed. Two pozzolanic materials were selected to make GR more recyclable: metakaolin (MK) and spent catalyst waste (Z), received from fluidized-bed catalytic cracking process. Functional and environmental properties of standard cement pastes and mortars as well as binary and ternary combinations of GR with MK and Z were assessed. Results showed that enhanced mechanical strength, reduced water absorption and heavy metals release were obtained for compositions when GR was combined with one of the pozzolanic material MK or Z. Microstructural analysis revealed that due to addition of pozzolan the surface of GR particles was covered by a layer of hydration products. In particular, the use of MK led to the formation of more porous layer whereas application of Z tends to the formation of a dense-layered structure on the surface of GR. N2 sorption results showed that contrary to MK the incorporation of Z into cement composition with GR reduced volume of small capillary pores, and therefore, resulted in lower water absorption and heavy metals release. The obtained results suggest that the application of Z appears to be advantageous pozzolan for the stabilization of SS-biomass gasification residue in cement-based materials.