Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-19T13:12:37Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese de Doutorado - João Nunes - Recuperação de Pb de Escória Metalúrgica por Flotação.pdf: 3142676 bytes, checksum: 24077634f2b469c913c04a7ae58a9678 (MD5) / Made available in DSpace on 2016-04-19T13:12:37Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese de Doutorado - João Nunes - Recuperação de Pb de Escória Metalúrgica por Flotação.pdf: 3142676 bytes, checksum: 24077634f2b469c913c04a7ae58a9678 (MD5) Previous issue date: 2015-10-07 / As empresas produtoras de baterias chumbo-ácido são obrigadas, por lei, a reciclar as sucatas de baterias usadas. Em Pernambuco, a reciclagem é feita por processo pirometalúrgico que gera um resíduo denominado de escória, tendo como principais elementos o chumbo e o ferro. Assim, o presente trabalho teve como objetivo estudar a possibilidade de reaproveitar o chumbo contido nesta escória, através do método de flotação. Este reaproveitamento trará um ganho ambiental e econômico a empresa, devido a redução do seu passivo e o alto valor agregado do chumbo no mercado internacional, respectivamente. A fim de caracterização minerológica e química da escória, foram realizadas análises por difração de raios X (DRX), fluorescência de raios X (FRX) e microscopia eletrônica de varredura (MEV), o que possibilitou a escolha de uma rota ideal de tratamento deste resíduo. Os testes de flotação foram realizados em uma célula mecânica de bancada, estudando-se a influência do tipo de coletor, concentração do coletor, tempo de condicionamento, pH da polpa, tempo de flotação, tipos de espumantes de flotação (o metil-isobutil-carbinol - MIBIC e eter-poliglicólico - F650) e ação de agentes modificadores (amido, o sulfeto de sódio e o querosene) com diferentes funções, tais como depressores de ferro, ativadores de chumbo e extensor de cadeia carbônica para aumentar a recuperação do chumbo, respectivamente. Os resultados mostraram que é possível uma recuperação de 54,4 % do chumbo da escória com as partículas na faixa granulométrica de 150 – 400 mesh, com o coletor mercaptobenzotiazol, a uma dosagem de 1.000 g/t, pH 9,0 e tempo de flotação de 20 min. As análises de MEV detectaram a presença de chumbo no interior de partículas de ferro, o que limita a possibilidade de melhorar a sua recuperação. Por sua vez, o xantato etílico de sódio foi bastante seletivo, proporcionando um concentrado com apenas 0,4 % do ferro contido na alimentação, com teor de chumbo de 22,9 %. O teor de chumbo apresentou um valor inferior a 40,0 %, meta proposta pela empresa, devido a presença de carbono no concentrado de flotação, o que não foi considerado um problema, pois os testes piloto mostraram que é possível a sua reutilização na metalurgia do chumbo. / Factories of lead-acid batteries are required by law to recycle battery waste. In Pernambuco, the waste is recycled by a pyrometallurgical process, which produces a residue called slag, that has as main elements lead and iron. Therefore, this work had as a target to study the possibility of reusing the lead of the slag of battery scrap, through the flotation method. This waste recycling will give the company an environmental and economic value, due to the reduction of the quantity of slag and due to a greater recuperation of the lead, especially since its price has been increasing in the international market. For the purpose of minerológica and chemical characterization of the slag, it was performed an analysis by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM), which allowed the choice of an ideal treating for this residue. Flotation tests were carried out in a laboratory cell to study the influence of the type of reactants, the reactant concentration, the adaptation time of the reactants, pH of the pulp, the flotation time, sparkling types of flotation (methyl-isobutyl- carbinol - MIBIC and ether polyglycol - F650) and types of modifying agents (starch, sodium sulfide and kerosene) with different functions, such as iron depressants, carbon chain extender to increase the lead recovery respectively. The results showed that it is possible to arrive at a recovery of 54.4% of the lead with the particles in the size range of 150 - 400 mesh, when we use mercaptobenzothiazole as reactants of flotation, at a dosage of 1000 g/ton, pH 9.0 and flotation time of 20 min. The SEM analysis detected the presence of lead inside the iron particles, which limits the possibility of improving and increasing its recovery. In turn, the sodium ethyl xanthate was quite selective, providing a concentrate with only 0.4% of the iron contained, in relation to the initial mass, and with lead concentration of 22.9%. The lead content showed a value less than 40.0%, of the target proposed by the company, due to the presence of carbon in the form of coke on flotation concentrate, which was not considered a problem since pilot tests showed that it is possible to reuse it in the metallurgical process.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI)

No description available.

In developing photovoltaic technology for commercial use, it is essential to prioritize low cost, high efficiency, and long-term stability, along with low toxicity and quick energy payback time. Organic-inorganic metal halide perovskites are among the most promising photovoltaic materials due to their exceptional efficiency and cost-effectiveness. However, their practical significance remains unclear due to their notoriously short device operation duration. Mixed-metal tin-lead perovskites are a class of perovskites that have captured researchers' attention due to their unique optoelectronic features, including a small bandgap, making them useful for various applications (tandems, NIR light detection, and imaging e.g.). Still, the low ambient stability of tin-lead perovskites obstructs their commercialization, necessitating extensive research into their underlying breakdown mechanisms. This study aims to better understand these mechanisms and the involvement of halide chemistry, specifically emphasizing the significant role of iodine in perovskite deterioration. Our findings reveal that tin-lead-based perovskites experience cyclic degradation, with iodine and SnI4 as key degradation products that harm the stability of the perovskite. Investigating the impact of iodine is critical because it is a common component of the perovskite material, and its presence has been shown to play a crucial role in the optoelectronic properties of the perovskite. However, the presence of iodine can also lead to the degradation of the perovskite material over time, reducing the efficiency and lifespan of the perovskite solar cells. Therefore, understanding the role of iodine in perovskite deterioration is essential to improve the stability and durability of tin-lead perovskites and bring them closer to commercialization. By gaining insight into the degradation mechanisms of tin-lead perovskites, we can develop effective strategies to mitigate their degradation, enhance their stability and lifespan, and unlock their full potential for use in various photovoltaic applications, contributing to a more sustainable and environmentally conscious future.

The purpose of this study was to determine the optimum phosphate treatment method to stabilize lead contaminated soil from a firing range. Seven different phosphate sources at five different concentrations were added to soil collected from a firing range on a military base. A series of tests were performed to determine a generic phosphate treatment method. The selected generic phosphate treatment was compared to an untreated control soil sample and to four commercially available treatments provided by invited vendors selected from industry. The four vendors processes, control, and generic treatments were subjected to a series of physical and chemical tests at 0, 14, and 28 days of curing time to determine the effectiveness of each treatment. The generic treatment using Hydroxyapatite developed in the MSU laboratory was competitive with three vendors? treatments. The fourth vendor?s treatment was more effective at reducing the lead leachability of the contaminated soil.

No description available.

No description available.

No description available.

No description available.