Recovery of Lead and Noble Metals After Processing Printed Circuit Boards From Cell Phones by Leaching With Mixtures Containing Hydrogen Fluoride

Abstract

This work examines the leaching of printed circuit boards (PCBs) from cell phones in aqueous solutions containing HF + H 2 O 2 or HF + NaClO under mild experimental conditions. The PCBs were not ground but were previously treated with 6 mol L -1 NaOH at 50 o C for 1 h to remove their soldering mask. , respectively. The processing of the solid residue is also described in detail. It was leached with water at ~90 o C followed by HNO 3aq. at 25 o C. Lead, palladium and silver were recovered in this order, leaving gold as final solid. After 1 h at [35][36][37][38][39][40] o C, 5 mol L -1 HF + 0.3 mol L -1 NaClO mixtures leached the base metals, copper, gold and palladium. Gold was recovered by liquid-liquid extraction with methyl isobutyl ketone. Silver precipitated as chloride. This salt was isolated by leaching with NH 3aq . Loss of fluoride ions (as HF) was below 0.5 wt.% after leaching and handling the solid residue.

Waste Electrical and Electronic Equipment: The Anthropocene Knocks on Our Door

“…204 Esse pensamento é fortemente centrado no fornecimento crítico de alguns metais que aparecem em EEE. 34,205,206 A metodologia envolve obrigatoriamente compromisso com a segurança, aspectos econômicos e a avaliação dos impactos ambientais (emissões de CO2 etc.). 203 Segundo o protocolo estabelecido na portaria europeia 2002/96/EC, deve-ser fazer a remoção de partes perigosas em EEE em plantas específicas para esse fim.…”

“…Outros itens incluídos nesse protocolo são: capacitores, PCI, cartuchos de impressora, componentes contendo amianto, mercúrio e fibras cerâmicas, radioativos, retardantes de chama bromados e cabos elétricos externos. 49,193,205 A versão atual do RoHS (Restriction of Certain Hazardous Substances, Restrição de Certas Substâncias Perigosas) é de 2011 (2011/65/EU), e começou a vigorar em setembro de 2012. Ele prevê a restrição ao uso de substancias tóxicas em EEE e facilitar a coleta e reciclagem/disposição dos mesmos usados.…”