Munchen D.D.,Programa de Pos Graduacao em Engineering de Minas |
Veit H.M.,Programa de Pos Graduacao em Engineering de Minas
Waste Management | Year: 2017
As a way to manage neodymium-iron-boron (NdFeB) magnets wasted in end-of-life hard disk drives (HDDs), a waste characterization is needed prior to a recycling process. Due to their magnetic properties, NdFeB magnets are essential in technological applications nowadays, thus causing an increase in the industrial demand for rare earth metals. However, these metals have a short supply, since they are difficult to obtain from ores, creating a critical market. In this work, a study of the characterization of sintered neodymium-iron-boron magnets was undertaken by qualitatively and quantitatively uncovering the neodymium recovery potential from this type of electronic waste. From the collection and disassembly of hard disk drives, in which the magnet represents less than 3% of the total weight, an efficient demagnetization process was proceeded at 320°C. Then, the magnet was ground and screened for an X-ray diffraction (XRD) analysis, which showed the Nd2Fe14B tetragonal phase as the dominant constituent of the sample. An analysis was also carried out in a scanning electron microscope (SEM) and an inductively coupled plasma optical emission spectrometer (ICP-OES), where the magnet composition showed 21.5wt% of neodymium and 65.1wt% of iron, among other chemicals. This Nd content is higher than the one found in Nd ores, enhancing the recyclability and the importance of waste management. © 2017 Elsevier Ltd.
Gabriel A.P.,Programa de Pos graduacao em Engineering de Minas |
Grochau I.H.,Programa de Pos graduacao em Engineering de Minas |
Santana R.M.C.,Programa de Pos graduacao em Engineering de Minas |
Veit H.M.,Programa de Pos graduacao em Engineering de Minas
Polimeros | Year: 2013
The cathode ray tube (CRT) technology-used in televisions and monitors for more than 60 years-has generated a lot of waste, now that is has been replaced by newer technologies such as plasma, liquid crystal display (LCD), and light-emitting diodes (LED). There are no official statistics on the amount of waste generated in Brazil; however, for some countries, such as the United States, China, and Taiwan, the estimated annual disposal of televisions and monitors is 3.2 million, 5 million, and 1 million, respectively. Monitors mainly contain polymers, metals, and ceramics, some of which may be hazardous. This work is focused on characterization and recycling of polymeric frames of CRT monitors. Monitors, damaged and obsolete, were collected and separated by brand, comminuted, and then injected to obtain the samples to be used in mechanical tests. The results pointed to the same polymeric material being used, viz. acrylonitrile butadiene styrene (ABS), regardless of the brand. The mechanical properties varied across different brands, probably because of different compositions. This variation was also observed in the analysis of the fracture surface of the samples after the tensile test. On the basis of the results, it can be concluded that the recycled material showed satisfactory mechanical performance, enabling recycling technically.
Zoppas F.M.,CONICET |
Marchesini F.A.,CONICET |
Devard A.,CONICET |
Bernardes A.M.,Programa de Pos Graduacao em Engineering de Minas |
Catalysis Communications | Year: 2016
Catalysts containing 1.8 wt.% of Pd and different In loadings were prepared by sequential electroless plating on activated carbon felts (ACF). Homogeneous structures were obtained, with In particles deposited at the top of a tiny Pd film. The catalyst with the higher In loading (Pd:In ratio of 2.0) presented high activity and good selectivity towards nitrogen, with negligible deactivation after 6 h of time-on-stream and three consecutive nitrate pulses. Besides the promising catalytic behavior, PdIn/ACF have the advantages of an open structure, which is highly accessible to the reactants, with no need of separation after the reaction. © 2016 Published by Elsevier B.V.