La Investigación Siderúrgica en el CENIM

Se realiza una revisión de los hitos más relevantes en la investigación siderúrgica realizada en el CENIM en los ultimos 60 añosCSICPeer reviewe

Reciclado de materiales compuestos de matriz polimérica

Los materiales compuestos se pueden clasificar en tres grandes grupos: Matriz Polimérica (PMC) (Polymer-Matrix Composites), Matriz Metálica (MMC) (Metal-Matrix Composites) y Matriz Cerámica (CMC) (Ceramic-Matrix Composites). Este trabajo se centra en los materiales compuestos de matriz polimérica (PMC)

Environmental impact and management of phosphogypsum

The production of phosphoric acid from natural phosphate rock by the wet process gives rise to an industrial by-product called phosphogypsum (PG). About 5 tons of PG are generated per ton of phosphoric acid production, and worldwide PG generation is estimated to be around 100–280 Mt per year. This by-product is mostly disposed of without any treatment, usually by dumping in large stockpiles. These are generally located in coastal areas close to phosphoric acid plants, where they occupy large land areas and cause serious environmental damage. PG is mainly composed of gypsum but also contains a high level of impurities such as phosphates, fluorides and sulphates, naturally occurring radionuclides, heavy metals, and other trace elements. All of this adds up to a negative environmental impact and many restrictions on PG applications. Up to 15% of world PG production is used to make building materials, as a soil amendment and as a set controller in the manufacture of Portland cement; uses that have been banned in most countries. The USEPAThe authors are grateful to AECI (project N A/5537/06) and to the Spanish National R&D&I Plan (Project CTQ2008-02012/PPQ) for the financial support of this study. Hanan Tayibi is grateful to the CSIC (Spanish National Research Council) for an I3P contract (I3PDR-6-01).Peer reviewe

Carbon-based nanomaterials for gold (III) recovery: kinetics and loading investigations

Currently, the development of different smart technology to recover or eliminate strategic or toxic metals from liquid effluent is constant. Among the different process developed to the treatment of liquid effluents bearing these types of metallic elements, include chemical or electrochemical precipitation, membrane based technology, ion exchange and adsorption. Adsorption is a high efficiency, cost-effectiveness and easily handing method to recover pollutants or strategic metals. Nowadays a research challenge is the development of new adsorbents. Among nanomaterials, carbon nanomaterials have adequate properties to be used as metal adsorbent. On the other hand gold is one of the most precious elements in the world. The price in 2015 of this strategic metal is 1.376 $/kg. Besides its uses in jewellery it is highly used in different industries, so it is important the gold recovery from liquid effluents generated from these various industries. The adsorption method is a way to treat these types of effluents, characterized for their low gold concentration. The aim of this research was to optimize various operational parameters, and thus obtain efficient carbon nanotubes processing for gold (III)-bearing effluents. The adsorption of gold (III) by carbon nanofibers (CNF), carbon multiwalled (MWCN) and carbon multiwalled with carboxyl group (MWCN_ox) systems were investigated. The experimental parameters which may influence gold adsorption were investigated, i.e. stirring speed of the aqueous solutions, adsorbent dosage, acid concentration, temperature etc. Figure 1 shows the effect of the acid concentration on the Au(III) adsorption to the three adsorbent. It can be seen that the adsorption Au(III) decreases with the increase of HCl concentration. Probalby it is due the existence of other gold species, such as HAuCl4, at the higher hydrochloric solution against the presence of the predominant AuCl4- species in the more dilute HCl solutions which are more adsorbable than the gold-acid form. SEM studies of gold loaded carbon nanomaterials show on the surface dark particles, Figure 2. The EDS of the dark particles show two peaks for Lα(9.7 keV) and Mα (2.1 keV) characteristic of metallic gold. Probably this reduction occurs on the carbon surface, related with the metal reduction. The isotherm and kinetic studies of the carbon nanomaterial-Au(III) system show a different behavior in function of the carbon nanomaterial used as adsorbent. The experimental data obtained using the MWCNT and CNF fit better to a pseudo second order equation and an isotherm Freundlich model. The three carbon nanomaterials, appeared to be a promising material for recovery of Au(III) from this type of acid solutions in the optimal experimental for each one of them condition.Peer reviewe

Thermal dehydration kinetics of phosphogypsum

© 2015 CSIC. Phsophogypsum is a by-product from the processing phosphate rock. Before the use of it in cement industry such as setting regulator is necessary a study of dehydration reaction of phosphogypsum to avoid the false setting during the milling. The aim is to study the thermal behavior of two different phosphogypsum sources (Spain and Tunisia) under non-isothermal conditions in argon atmosphere by using Thermo-Gravimetriy, Differential Thermal Analysis (TG-DTA) and Differential Scanning Calorimetry (DSC). DSC experiments were carried out at temperatures ranging from ambient to 350 °C at different heating rates. The temperatures of conversion from gypsum to hemihydrate and anhydrite states and heat of dehydration were determined. Various methods were used to analyze the DSC data for reaction kinetics determination. The activation energy and frequency factor were calculated for dehydration of phosphogypsum. Activation energy values of the main dehydration reaction of phosphogypsum were calculated to be approximately 61-118 kJ/mol.The authors are grateful to the Spanish National R&D&I Plan and FEDER (Project CTQ200802012/PPQ) for the financial support of this study.Peer Reviewe

Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

A Spanish hazardous waste from tertiary aluminium industry was used as a raw material for the synthesis of calcium aluminate. An amorphous precursor was obtained by a hydrothermal method at different values of pH. The transformation of the precursor in a crystalline aluminate was followed by TG/DTA up to 1300 C. At temperatures between 719 and 744 C, the precursors evolve towards the formation of C12A7 which becomes CA at circa 1016 C. Mass spectrometry coupled to thermal analyser allowed the identification of the decomposition productsMEC for financing project CTM2005-01964 and the company Recuperaciones y Reciclajes Roman S.L. (Fuenlabrada, Madrid, Spain) for supplying the waste and Dr. M. I. Martı´n for the FRX analysis and Dr. I. Padilla for the technical assistance. Laura Delgado-Gonzalo is grateful to the CSIC (Spanish National Research Council) for an I3P contractPeer reviewe

Technical characterization of sintered glass-ceramics derived from glass fibers recovered by pyrolysis

Sintered wollastonite-plagioclase glass-ceramics were prepared through crystallization of a parent glass generated by vitrification of pyrolysis residual glass fibers that had been pyrolytically recovered from waste composite materials. A vitrifiable mixture consisting of 95 wt.% glass fiber and 5 wt.% Na2O was melted at 1450ºC to obtain a glass frit. The glass-ceramic materials were produced by a sinter-crystallization process from the powdered glass frit. The effect of firing temperature on the properties of sintered glass-ceramics was investigated. The sintering behaviour of glass-ceramic tiles was evaluated by means of water absorption, apparent porosity and bulk density. In addition, the mineralogical and microstructural characterization of these tiles was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results from experiments such as water absorption, bending strength, chemical resistance and stain resistance have shown that the developed glass-ceramic materials possess technological properties very suitable for architectural applications.Dr. M.I. Martín thanks the Spanish National Research Council (CSIC), co-financed by the European Social Fund Operational Programme 2007-2013 Adaptability and Employment Multiregional, for the contract JAE-Doc_08-00032Peer reviewe

Study of the thermal behavior of the aluminium dust stabilized with gypsum

[ES]El polvo de aluminio (pAl) es un residuo peligroso procedente de la metalurgia secundaría del aluminio. Con objeto de reducir la reactividad del mismo, en el CENIM se ha desarrollado un proceso de estabilización/solidificación mediante su fraguado con yeso. En este trabajo se presenta el estudio del comportamiento térmico del pAl estabilizado con el yeso, con el fin de establecer la influencia del residuo en las reacciones de hidratación/deshidratación del yeso durante el proceso del fraguado, a saber: deshidratación parcial del sulfato calcico dihidrato, deshidratación del hemihidrato, deshidratación del hidróxido de aluminio y transformación de anhidrita soluble en anhidrita insoluble. Asimismo se ha estudiado la cinética asociada a cada una de las reacciones anteriormente mencionadas mediante Calorimetría Diferencial de Barrido.[EN]The aluminium dust is a hazardous waste from the secondary aluminium remelting industry. A stabilization/solidification process was developed at CENIM with the aim of decreasing its reactivity. Gypsum was used as a binder material. Tliis work summarizes the study of the thermal behavior of the aluminium dust stabilized with gypsum, in order to establish the influence of the residue in the reactions of hydration/dehydration of the gypsum during the hardening process, namely: partial dehydration of calcium sulphate dihydrate, dehydration of calcium sulphate hemi'hydrate, dehydration of aluminium hydroxide and anhydrite soluble/anhydrite insoluble transformation. The activation energy associated to all those reactions was determined by Differential Scanning Calorimetry.Los autores agradecen a la Consejería de Educación de la Comunidad de Madrid la financiación del proyecto (07M/0136/2000) y a la empresa Recuperación y Reciclaje Román por el apoyo a esta investigación.Peer reviewe

ZnO synthesis from Zn-C and alkaline spent batteries by alkaline leaching: properties and applications

6th EUCHEMS Chemistry Congress. Seville, Spain, 11th-19 th September 2016This report describes the leaching experiments to recover Zn from spent household Zn-C and alkaline batteries. Basic zinc carbonate Zn5(CO3)2(OH)6 nanoparticles have been successfully synthesized by the leaching of an ammoniacal ammonium carbonate solution of black mass. Zinc oxide (ZnO) were prepared by the thermal decomposition of basic zinc carbonate precursor. The synthesis of ZnO micro and nanostructures is carried out through the vapor solid growth process.Ministerio de Economía y Competitividad MINECO (Projects MAT 2012-31959 and CSD2009-00013) and MINECO/FEDER (MAT2015-65274-R; 2016-2019). This work has supported by the Envirobat España S.L.Peer reviewe

Production of Sponge Iron Powder by Reduction of a By-product of the Steelmaking Industry

Ref. Revista/libro: Proceedings of the International Powder Metallurgy Congress & Exhibition (PM2010). Volumen I. Editors: European Powder Metallurgy Association (EPMA). Florencia (Italia), October 2010.Rolling mill scale is a solid steelmaking by-product that contains metallic iron (Fe), wustite (FeO), hematite (α-Fe2O3) and magnetite (Fe3O4). It also contains traces of non-ferrous metals, alkaline compounds and oils from the rolling process. A study is made of the reduction of mill scale to sponge iron, in covered crucibles, using coke at different temperatures (1050º-1150ºC) and times (3-12 h). The final treatment of the samples was carried out in a hydrogen atmosphere furnace at 900ºC for 0.5 h. The reduced samples are studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Oxygen analysis is carried out by combustion in a LECO oven. The reduction of mill scale allows the new use and development of this material to obtain sponge iron that can be re-used to the electric furnace as metallic load in steel manufacturing or as a raw material in the production of iron-base powder metallurgy parts.European Powder Metallurgy Association (EPMA).Peer reviewe