Browsing by Author "Margarido, F."
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- Battery recycling by hydrometallurgy : evaluation of simultaneous treatment of several cell systemsPublication . Nogueira, Carlos; Margarido, F.A research work has being carried out aiming at evaluating the possibility of treating simultaneously several electrochemical systems of spent batteries using the same process, in order to overcome the high costs and difficulties of selective collection and sorting. Zn-MnO2 systems, representing more than 75% of portable battery market, shall be treated in dedicated processes. The treatment assessment using a single hydrometallurgical process of the other major systems (NiCd, NiMH and Li-ion), having Ni and Co as main metals, was the aim of the research work here reported. Sulfuric acid leaching was demonstrated to be adequate for dissolving more than 90% of the metals of interest contained in batteries. The subsequent separation of metals by solvent extraction, using organophosphorous extractants like DEHPA and Cyanex 272, allowed the production of pure solutions of rare earths, cadmium/manganese, cobalt, nickel and lithium, enabling their further recovering
- Characterisation of automotive shredder residuePublication . Margarido, F.; Nogueira, CarlosThe autofluff residue of a Portuguese shredding facility was characterised aiming at identifying the presence of heavy metals in several constituents of these residues, in order to propose possible valorising solutions. Particle size analysis showed that average characteristic diameter (d50) was 6.5 mm, the coarser fractions (> 11 mm, representing 40% of weight) being essentially composed of plastic pieces, rubber, foams and textiles, particles in the range 2-11 mm being composed of mixed materials, while in particles below 2 mm (referred as fines) the presence of glass, ceramics and other inorganic materials became very frequent, in spite of a very fine foam was also detected in the very fine fractions. XRD analysis of fines allowed detecting the crystalline phases quartz, calcite, rutile and magnetite. Elemental analysis by EDXRF was carried out on several fractions in the particle size range 0.02-2.0 mm, showing the presence of practically all the elements detected in all fractions, namely Fe, Zn, Cu, Pb, Ba, Sn, and also traces of Cd, Sb, Mo and Sr. Some of these metals are hazardous and can be problematic in what concerns the possible valorisation of the residue.
- Characterization of spent Ni-MH batteriesPublication . Cabral, Marta; Nogueira, Carlos; Margarido, F.
- Characterization of Spent Ni-MH BatteriesPublication . Cabral, Marta; Margarido, F.; Nogueira, CarlosSpent Ni-MH batteries are not considered too dangerous for the environment, but they have a considerable economical value due to the chemical composition of electrodes which are highly concentrated in metals. The present work aimed at the physical and chemical characterisation of spent cylindrical and thin prismatic Ni-MH batteries, contributing for a better definition of the recycling process of these spent products. The electrode materials correspond to more than 50% of the batteries weight and contain essentially nickel and rare earths (RE), and other secondary elements (Co, Mn, Al). The remaining components are the steel parts from the external case and supporting grids (near 30%) containing Fe and Ni, and the plastic components (<10%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. Phase identification by X-ray powder diffraction combined with chemical analysis and leaching experiments allowed advancing the electrode materials composition. The cathode is essentially constituted by 6% metallic Ni, 66% Ni(OH)2, 4.3% Co(OH)2 and the anode consists mainly in 62% RENi5 and 17% of substitutes and/or additives such as Co, Mn and Al.
- Collection of waste batteries in Portugal and BrazilPublication . Vieceli, N.; Margarido, F.; Durão, F.; Guimarães, C.; Nogueira, CarlosThe legal aspects governing the disposal of used batteries were established in the nineties of the last century in Brazil and Portugal. In Brazil the law establishes the implementation of a reverse logistics system of this waste, similar to the system of Portugal, in which there is an extended producer responsibility. Portugal, subjected to the targets set by the European Union, has increased collection rates, with emphasis on the role of management entities. In Brazil, progress and the development of strategies to increase the collection rate have been observed, nevertheless, challenges associated with the increase of the coverage of the collection of batteries and also the public information about the disposal are relevant, as well as combating irregularities. Moreover, given the growing concern over the shortage of raw materials, proper management, including the collection and recycling of these wastes, can be seen as an important opportunity for both countries.
- Comparison of processes for lithium recovery from lepidolite by H2SO4 digestion or HCl leachingPublication . Nogueira, Carlos; Margarido, F.; Vieceli, N.; Durão, F.; Guimarães, C.Lithium is becoming a strategic metal due to its important applications in secondary battery electrodes used in electronic appliances and also in electric traction vehicles. Lithium primary resources are brines and rock minerals, the former being nowadays almost exclusively used in the production of lithium commodities. With the expected increase in lithium demand, the development of competitive technologies for recovery lithium from ores like pegmatites is getting imperative. The high energy and reagents consumption in processing minerals is an issue that should be considered. This paper presents some results on the comparison of two acid treatment routes for lepidolite, the H2SO4 digestion and HCl leaching. Before both chemical treatments, lepidolite was calcined at 800oC and was transformed in a more reactive species, ƒÀ-spodumene. The H2SO4 digestion at 175oC (followed by water leaching) allowed 88% Li recovery into the solution in 30 min. By the contrary, the HCl leaching process carried out at 90oC also achieved similar yields but only after 4 h of reaction. In both cases, an acid excess was used, but clearly higher for the essays with HCl. The H2SO4 digestion process was also advantageous in what concerns to selectivity over other contained metals. Al, Mn and Fe concentrations in solutions were substantially higher in the hydrochloric acid leaching. These results showed that the digestion with sulphuric acid can be a more efficient and competitive process.
- ELV recycling steps up a gear: development of improved sorting technologies for the non-ferrous fraction of auto-shreddersPublication . Nogueira, Carlos; Pedrosa, Fátima; Margarido, F.; Santos, R. Novais; Durão, F.; Guimarães, C.Although the number of end of life vehicles (ELVs) needing recycling is growing, due to processing limitations aluminium recycling rates are being hindered. A European-funded project - ShredderSort - aims to contribute to new solutions to the aluminium recycling industry. More than 10 million tons of automotive waste from end of life vehicles (ELV) are generated yearly in the EU and the values are continuously increasing. ELV wastes are managed by the auto-shredder plants which process ELVs through a series of mechanical and physical operations in order to separate the materials into different streams: ferrous, non-ferrous, heavy non-metal and fluff. Ferrous materials, constituting more than 60wt% (percentage by weight), are sent to steel-making plants, while the non-ferrous (NF) fraction, rich in aluminium and representing slightly less than 10wt%, is processed to separate some alloys.
- End-of-life Zn–MnO2 batteries: electrode materials characterizationPublication . Cabral, Marta; Pedrosa, Fátima; Margarido, F.; Nogueira, CarlosPhysical and chemical characterization of several sizes and shapes of alkaline and saline spent Zn–MnO2 batteries was carried out, aiming at contributing for a better definition of the applicable recycling processes. The characterization essays included the mass balance of the components, cathode and anode elemental analysis, the identification of zinc and manganese bearing phases and the morphology analysis of the electrode particles. The electrode materials correspond to 64–79% of the total weigh of the batteries, with the cathodes having clearly the highest contribution (usually more than 50%). The steel components, mainly from the cases, are also important (17–30%). Elemental analysis showed that the electrodes are highly concentrated in zinc (from 48–87% in anodes) and manganese (from 35–50% in cathodes). X-Ray powder diffraction allowed for identifying several phases in the electrodes, namely zinc oxide, in the anodes of all the types of saline and alkaline batteries tested, while zinc hydroxide chloride and ammine zinc chloride only appear in some types of saline batteries. The manganese found in the cathode materials is present as two main phases, MnO·Mn2O3 and ZnO·Mn2O3, the latter corroborating that zinc migration from anode to cathode occurs during the batteries lifespan. A unreacted MnO2 phase was also found presenting a low crystalline level. Leaching trials with diluted HCl solutions of alkaline and saline battery samples showed that all zinc species are reactive attaining easily over than 90% leaching yields, and about 30% of manganese, present as Mn(ii/iii) forms. The MnO2 phase is less reactive and requires higher temperatures to achieve a more efficient solubilization.
- Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphitePublication . Vieceli, N.; Nogueira, Carlos; Guimarães, C.; Pereira, Manuel F. C.; Durão, F.; Margarido, F.ABSTRACT: The hydrometallurgical extraction of metals from spent lithium-ion batteries (LIBs) was investigated. LIBs were first dismantled and a fraction rich in the active material was obtained by physical separation, containing 95% of the initial electrode, 2% of the initial steel and 22% of plastic materials. Several reducers were tested to improve metals dissolution in the leaching step using sulphuric acid. Sodium metabisulphite led to the best results and was studied in more detail. The best concentration of Na2S2O5 was 0.1 M. The metals dissolution increased with acid concentration, however, concentrations higher than 1.25 M are unnecessary. Best results were reached using a stirring speed of 400 min(-1). The metals leaching efficiency from the active material (Li, Mn, Ni, Co) increased with the temperature and was above 80% for temperatures higher than 60 degrees C. The dissolution of metals also rose with the increase in the liquid/solid ratio (LAS), however, extractions above 85% can be reached at LAS as lower as 4.5 L/kg, which is favourable for further purification and recovery operations. About 90% of metals extraction can be achieved after only 0.5 h of leaching. Sodium metabisulphite can be an alternative reducer to increase the leaching of Li, Mn, Co, and Ni from spent LIBs.
- Integration of physical operations in the hydrometallurgical processing of spent Zn-MnO2 batteriesPublication . Pedrosa, Fátima; Feu, J. P.; Cabral, Marta; Nogueira, Carlos; Margarido, F.The recycling of spent Zn-MnO2 batteries by hydrometallurgy involves the leaching of material previously treated by physical processing to allow the liberation of electrode particles and the separation of unwanted scrap. The integration of these physical operations with leaching is therefore crucial for the optimization of the process, allowing achieving high recovery yields of zinc and manganese and minimizing reactants consumption and iron contamination. In this paper, several options involving physical processing and leaching with sulphuric acid are presented and discussed. After batteries shredding and disaggregation, the separation of steel scrap was performed by sieving or magnetic separation, and the remaining solids were treated by leaching. These options were compared, in terms of metals recovery and contamination, with the alternative of direct leaching of all the shredded fractions without physical treatment. The separation of the steel scrap by sieving or magnetic separation allowed the removal from the circuit of 37 or 49% of iron, respectively, with losses of 15 or 6% of zinc and 2 or 4% of manganese. Therefore more than 50% of iron remained in the process, which was attributed to the presence of iron oxides formed by the corrosion of the battery cases. In the leaching operation, zinc dissolution was very effective (yields above 97%) while manganese is strongly depended from the process option, being its leaching proportional to the presence of scrap (yields of 80%, 56% and 43%, respectively in direct leaching, sieving / leaching and magnetic separation / leaching). These results showed that iron plays an important role in the reductive leaching of manganese species (III or IV), and so the presence of steel scrap in leaching, besides disadvantages concerning solutions contamination, contributes positively for the leaching efficiency