RECOVERY OF LEAD AND NOBLE METALS AFTER PROCESSING PRINTED CIRCUIT BOARDS FROM CELL PHONES BY LEACHING WITH MIXTURES CONTAINING HYDROGEN FLUORIDE

Quimica nova

Corrêa, Roger de Souza¹  Silva, Walner Costa² 

[1] Instituto de Engenharia Nuclear, Rio de Janeiro, Brazil;Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

关键词: PCB;    metals recovery;    acidic leaching;    gold;    silver;    hydrofluoric acid.;   

DOI  :  10.21577/0100-4042.20170267

学科分类：化学（综合）

来源: Sociedade Brasileira de Quimica

【 摘 要 】

This work examines the leaching of printed circuit boards (PCBs) from cell phones in aqueous solutions containing HF + H2O2 or HF + NaClO under mild experimental conditions. The PCBs were not ground but were previously treated with 6 mol L-1 NaOH at 50 ºC for 1 h to remove their soldering mask. The HF + H2O2 mixtures leached copper and base metals (except lead) at 35-40 ºC, leaving a solid residue containing lead and noble metals. Leaching was fastest (1 h) when HF and H2O2 concentrations were at least 5 mol L-1 and 3 mol L-1, respectively. The processing of the solid residue is also described in detail. It was leached with water at ~90 ºC followed by HNO3aq. at 25 ºC. Lead, palladium and silver were recovered in this order, leaving gold as final solid. After 1 h at 35-40 ºC, 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 NH3aq. Loss of fluoride ions (as HF) was below 0.5 wt.% after leaching and handling the solid residue.

【 授权许可】

CC BY