Physical, thermal and mechanical study of MPC formulated with LG-MgO incorporating phase change materials as admixture

The high environmental impact generated by using of Ordinary Portland Cement (OPC) has lead to the search for alternative materials in the field of civil and building engineering. In addition, there is a tendency to develop cements from industrial by-products, thus reducing pollution and emissions generated by their production. One of the best positioned cements to compete with OPC is Magnesium Phosphate Cement (MPC). The present work studies different dosages of MPC mortars formulated with low-grade MgO by-product (sustainable MPC) incorporating Microencapsulated Phase Change Materials (MPCM) and air entraining additive (AEA) as admixtures (Thermal Sustainable MPC) to improve the thermal behaviour of the material. The aim is developed a new eco-friendly material that leads to reducing energy consumption in buildings. The study is focused on the physical, thermal, and mechanical characterization of TS-MPC mortars to assess their potential use as a thermal prefabricated panel. The results allow to relate the amount of the MPCM and the additive percentage with the thermal and mechanical properties of the TS- MPC. Furthermore, is important to highlight the influence of MPCM not only in the thermal behaviour but also on the increase of the porosity. The experimental results show that the addition of both additives contributes substantially to the improvement of the thermal behaviour of the mortars and converts them on a suitable material to reduce thermal oscillations in buildings

Magnesium phosphate cements formulated with low grade magnesium oxide incorporating phase change materials for thermal energy storage

Magnesium Phosphate Cement (MPC) has become an essential reference for investigators seeking alternatives to the use of Ordinary Portland Cement (OPC) in building sector because of its high environmental impact. The research group developed a MPC formulated with low-grade MgO (LG-MgO) by-product, which could be considered as a sustainable MPC (sust-MPC). This research focuses on the incorporation of different percentages of Microencapsulated Phase Change Materials (MPCM) into sust-MPC, due to their ability to reduce energy consumption of heating, ventilating, and air conditioning (HVAC) systems. The study consists of an exhaustive characterization of thermal sustainable MPC (TS-MPC) dosages which incorporate air-entraining additive (AEA) and MPCM to improve their thermal behaviour. Thus, TS-MPC would reduce the use of HVAC systems contributing to the decrease of CO2 emissions and increasing energy efficiency in buildings. Moreover, properties such as bulk density, porosity, thermal conductivity, modulus of elasticity, compressive strength, and flexural strength are analysed to evaluate the potential use of these cements as a part of a passive conditioning system. Results show the proper behaviour of these cements to reduce thermal oscillation in buildings. Experimental results demonstrated the relation between the amount of the MPCM and the AEA percentage as well as the thermal and mechanical properties of the TS-MPC due to their contribution to increase the porosity. Furthermore, it should be noted the increase of porosity and the reduction of thermal conductivity of the optimal formulation, which are 60% higher and 50% lower than the sust-MPC obtained without MPCM and additive, respectively

Magnesium phosphate cements formulated with low grade magnesium oxide incorporating phase change materials for thermal energy storage

Magnesium Phosphate Cement (MPC) has become an essential reference for investigators seeking alternatives to the use of Ordinary Portland Cement (OPC) in building sector because of its high environmental impact. The research group developed a MPC formulated with low-grade MgO (LG-MgO) by-product, which could be considered as a sustainable MPC (sust-MPC). This research focuses on the incorporation of different percentages of Microencapsulated Phase Change Materials (MPCM) into sust-MPC, due to their ability to reduce energy consumption of heating, ventilating, and air conditioning (HVAC) systems. The study consists of an exhaustive characterization of thermal sustainable MPC (TS-MPC) dosages which incorporate air-entraining additive (AEA) and MPCM to improve their thermal behaviour. Thus, TS-MPC would reduce the use of HVAC systems contributing to the decrease of CO2 emissions and increasing energy efficiency in buildings. Moreover, properties such as bulk density, porosity, thermal conductivity, modulus of elasticity, compressive strength, and flexural strength are analysed to evaluate the potential use of these cements as a part of a passive conditioning system. Results show the proper behaviour of these cements to reduce thermal oscillation in buildings. Experimental results demonstrated the relation between the amount of the MPCM and the AEA percentage as well as the thermal and mechanical properties of the TS-MPC due to their contribution to increase the porosity. Furthermore, it should be noted the increase of porosity and the reduction of thermal conductivity of the optimal formulation, which are 60% higher and 50% lower than the sust-MPC obtained without MPCM and additive, respectively.Postprint (author's final draft

Procedimiento para la recuperación del germanio presente en cenizas de carbón

Procedimiento para la recuperación del germanio presen te en cenizas de carbón. El objeto de la presente invención se refiere a un procedi miento hidrometalúrgico para la recuperación del germa nio presente en cenizas de carbón que implica tres eta pas: 1) lixiviación de la ceniza para obtener una disolución acuosa de Ge; 2) extracción líquido-líquido con un siste ma formado por catecol como agente complejante del Ge, unido a un extractante orgánico constituido por una amina grasa o un compuesto de amonio cuaternario en un disol vente adecuado; dicho sistema actúa de forma selectiva sobre el Ge, separándolo de otros metales y concentrán dolo unas 100 veces con respecto a la solución acuosa de partida (lixiviado), y 3) precipitación del Ge para dar finalmente, tras su separación y calcinación, un producto sólido comercializable de Ge de gran pureza.Españ

Uniform convergence to the spectral radius and some related properties in Banach algebras

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016804 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Thermal study of low-grade magnesium hydroxide used as fire retardant and in passive fire protection

Low-grade magnesium hydroxide is being used with very promising results as flame retardant filler in polymeric materials and as aggregate in the formulation of mortars for passive fire protection, combining an economic and sustainable solution. Simultaneous TGA–DSC was used to evaluate low-grade magnesium hydroxide thermal decomposition in order to examine the suitability of this product for a broad range of temperatures. Thermal analysis in air shows an unexpected exothermic peak, as well as the endothermic peaks corresponding to the decomposition of magnesium hydroxide, magnesite and dolomite. Thermal decomposition using nitrogen as gasflowdoes not show the exothermic peak, whereas anewendothermic peak corresponding to decomposition of calcite appears. In situXRDpatterns collected in air atmosphere at high temperature allows determining the presence of anhydrite, which was related to direct sulphation of calcite from the sulphur trioxide generated during the combustion of petcoke adsorbed on the particle surface of the low-grade magnesium hydroxid

Characterisation and partition of valuable metals from WEEE in weathered municipal solid waste incineration bottom ash, with a view to recovering

As the demand for critical and valuable metals increases due to industrial developments, especially in electronics and high-technology industries, the search for novel and sustainable sources grows in significance. Incinerated municipal solid waste (MSW) is a potential source of valuable metals, since a lot of waste from electrical and electronic equipment (WEEE) is not recycled properly and are is managed together with the refuse fraction of MSW, which is often landfilled or incinerated. Bottom Ash (BA) is the main by-product of incinerated MSW, which has been characterized to assess the potential recovery of valuable metals. The determination of the total amount of valuable metals (Ag, Al, Au, Be, Co, Cu, Ga, Ge, In, Ir, Li, Ni, Pd, Pt, Sb, Ta, and W) in seasonal samples of weather bottom ash (WBA) was performed by a total acid digestion followed by a chemical analysis. Besides, a sequential extraction procedure (SEP) is conducted to define their partition. The characterisation has shown that the content of valuable metals in the incineration WBA, which was highest in the 0–2 mm fraction was much lower than in concentrated ores commonly used as primary sources. Moreover, the SEP showed little potential for the valorisation of most of the metals, as they are embedded in or bound to a silicic matrix or sintered metal oxides, and so their extraction requires strong-acid digestion or a highly oxidizing environment. This work contributes to the use of residual sources as secondary resources and to the correct management of the end-of-life electrical and electronic equipment. © 2019 Elsevier LtdThis work was partially funded by the Spanish Government (BIA2017-83912-C2-1-R). The authors would like to thank the companies SIRUSA and VECSA for their financial support and for providing access to sampling sites. The authors would like to thank the regional Catalan authorities for the accreditation of the quality of the research group: DIOPMA (2017 SGR 118). Mr. Maldonado-Alameda thanks the Catalan authorities for his postgraduate grant (FI-DGR 2017).Peer reviewe

Procedimiento para la recuperación del germanio presente en cenizas de carbón

Fecha de presentación internacional 29.06.2007.-- Titulares: Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC).[EN] The invention relates to a hydrometallurgical method for the recovery of germanium present in coal ash, which comprises three steps, namely: 1) leaching of the ash in order to obtain an aqueous Ge solution; 2) liquid/liquid extraction with a system formed with catechol as a Ge complexing agent and joined to an organic extractant formed by a fatty amine or a quaternary ammonium compound in a suitable solvent, said system acting selectively on the Ge, separating said Ge from other metals and concentrating same 100 times in relation to the initial aqueous solution (leachate); and 3) precipitation of the Ge such as to produce a solid marketable Ge product of high purity following separation and calcination.[ES] El objeto de la presente invención se refiere a un procedimiento hidrometalúrgico para la recuperación del germanio presente en cenizas de carbón que implica tres etapas: 1) lixiviación de la ceniza para obtener una disolución acuosa de Ge; 2) extracción líquido-líquido con un sistema formado por catecol como agente complejante del Ge, unido a un extractante orgánico constituido por una amina grasa o un compuesto de amonio cuaternario en un disolvente adecuado; dicho sistema actúa de forma selectiva sobre el Ge, separándolo de otros metales y concentrándolo unas 100 veces con respecto a la solución acuosa de partida (lixiviado), y 3) precipitación del Ge para dar finalmente, tras su separación y calcinación, un producto sólido comercializable de Ge de gran pureza.Peer reviewe

Physical, thermal and mechanical study of MPC formulated with LG-MgO incorporating phase change materials as admixture

The high environmental impact generated by using of Ordinary Portland Cement (OPC) has lead to the search for alternative materials in the field of civil and building engineering. In addition, there is a tendency to develop cements from industrial by-products, thus reducing pollution and emissions generated by their production. One of the best positioned cements to compete with OPC is Magnesium Phosphate Cement (MPC). The present work studies different dosages of MPC mortars formulated with low-grade MgO by-product (sustainable MPC) incorporating Microencapsulated Phase Change Materials (MPCM) and air entraining additive (AEA) as admixtures (Thermal Sustainable MPC) to improve the thermal behaviour of the material. The aim is developed a new eco-friendly material that leads to reducing energy consumption in buildings. The study is focused on the physical, thermal, and mechanical characterization of TS-MPC mortars to assess their potential use as a thermal prefabricated panel. The results allow to relate the amount of the MPCM and the additive percentage with the thermal and mechanical properties of the TS- MPC. Furthermore, is important to highlight the influence of MPCM not only in the thermal behaviour but also on the increase of the porosity. The experimental results show that the addition of both additives contributes substantially to the improvement of the thermal behaviour of the mortars and converts them on a suitable material to reduce thermal oscillations in buildings

Comparative study of magnesium by-products and vermiculite formulations to obtain fire resistant mortars

There exists an increasing concern about the dangers originated in a building g in case of fire. In this work the behaviour of vermiculite as aggregate in fireproof mortars was compared with mortars formulated with two magnesium by-products aggregates which undergo an endothermic decomposition. Fire resistance and mechanical properties were evaluated. An optimal mixture of both magnesium by-products as aggregates allows formulating mortars that improve fire resistance at temperatures greater than 450 C compared with vermiculite mortars. It would be interesting to obtain mortars formulated with magnesium by products and vermiculite to study possible synergic effects.Peer Reviewe