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Master's Dissertation
DOI
10.11606/D.3.2016.tde-07072016-152302
Document
Author
Full name
Franco Alves Lavacchini Ramunno
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2015
Supervisor
Committee
Tenório, Jorge Alberto Soares (President)
Bernardes, Andrea Moura
Espinosa, Denise Crocce Romano
Title in Portuguese
Estudo cinético da lixiviação de metais de placas de circuito impresso obsoletas.
Keywords in Portuguese
Cinética
Lixiviação
Placas de circuito impresso
Resíduos (Reciclagem)
Abstract in Portuguese
O processo tradicional de recuperação de metais de resíduos de equipamentos eletroeletrônicos (REEE) geralmente envolve processamento pirometalúrgico. Entretanto, o uso desta tecnologia para processar placas de circuito impresso (PCI) obsoletas pode levar à liberação de dioxinas e furanos, devido à decomposição térmica de retardantes de chama e resinas poliméricas presentes no substrato das placas. Portanto, este trabalho propõe uma rota hidrometalúrgica para recuperação de metais. O comportamento dos metais, com destaque para cobre, zinco e níquel, durante a lixiviação ácida, foi estudado em três temperaturas diferentes (35ºC, 65ºC e 75ºC), com e sem adição de um agente oxidante (peróxido de hidrogênio H2O2). A cinética de dissolução ácida desses metais foi estudada baseada na análise química por ICP-OES (Espectrometria de emissão ótica por plasma acoplado indutivamente) e EDX (Espectroscopia de fluorescência de raios-X por energia dispersiva). O balanço de massa e a análise química indicaram que a etapa de lixiviação sem adição de oxidante é pouco eficaz na extração dos metais, sendo responsável pela dissolução de menos do que 6% do total extraído. A 65ºC e H2SO4 1 mol/L, com adição de 5 mL de H2O2 (30%) a cada quinze minutos e densidade de polpa de 1 g / 10 mL, 98,1% do cobre, 99,9% do zinco e 99,0% do níquel foram extraídos após 4 horas. A cinética de dissolução desses metais é controlada pela etapa da reação química, seguindo, dependendo da temperatura, a equação 1 (1 XB)1/3 = k1.t ou a equação ln (1 XB) = k4.t.
Title in English
Kinetic study on leaching of metals from waste printed circuit boards.
Keywords in English
Kinetics
Leaching
Printed circuit boards
Abstract in English
The traditional process for recovery of metals from waste electric and electronic equipment (WEEE) usually involves pyrometallurgical processing. However, the application of this technology to processing waste printed circuit boards (WPCBs) might lead to the formation of dioxins and furans, due to thermal degradation of flameretardants and polymeric resins present in the board substrate. Therefore, this work proposes a hydrometallurgical route for the recovery of metals. The acid leaching behavior of metals, especially copper, zinc and nickel, has been investigated at three different temperatures (35ºC, 65ºC e 75ºC) with and without the addition of an oxidizing agent (hydrogen peroxide H2O2). The dissolution kinetics for acid leaching of these metals was studied based on chemical analysis by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry) and EDX (Energy Dispersive X-ray Spectroscopy). The mass balance and chemical analysis showed that the acid leaching without the addition of an oxidizing agent is inefficient at extracting the metals, being responsible for less than 6% of the total mass leached during the hydrometallurgical route proposed. At 65ºC with 1 mol/L H2SO4 added 5 mL H2O2 (30%) each fifteen minutes under pulp density of 1 g / 10 mL, 98,1% of copper, 99,9% of zinc and 99,0% of nickel were extracted after 4 hours. The dissolution kinetics of these metals, depending on the temperature, followed 1 (1 XB)1/3 = k1.t or ln (1 XB) = k4.t, i.e. chemically controlled reaction model.
 
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Publishing Date
2016-07-08
 
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