Open AccessTotal Recovery of Gold Contained in Computer Printed Circuit Boards. Leaching Kinetics of Cu, Zn and Ni
Author(s) -
María Isabel Reyes,
Isauro Rivera,
Francisco Patiño,
Mizraím U. Flores,
Martín Reyes
Publication year - 2017
Publication title -
journal of the mexican chemical society
Language(s) - English
Resource type - Journals
ISSN - 2594-0317
DOI - 10.29356/jmcs.v56i2.312
Subject(s) - zinc , metal , copper , leaching (pedology) , dissolution , nickel , activation energy , nuclear chemistry , materials science , kinetics , substrate (aquarium) , chemistry , analytical chemistry (journal) , metallurgy , chromatography , environmental science , physics , oceanography , quantum mechanics , soil science , soil water , geology
In this study a thorough characterization of certain printed circuit boards has been carried out; it was found that they are made up of a polymer layer, a metal layer of Cu, Zn and Ni, and a gold substrate. A kinetic study of the acid dynamic leaching of copper, zinc and nickel has been carried out, finding out that these elements’ dissolution allows the gold substrate to be physically separated; then, the gold particles are separated from the polymer by filtration. The reaction orders were calculated vs. H 2 SO 4 concentration, and the activation energy was calculated as well; reaction orders of n = 0.265, n = 0.247 and n = 0.245 were found for Cu, Zn and Ni respectively, while Ea = 86.3, Ea = 95.3 and Ea = 11.2 kJ/mol were found for Cu, Zn and Ni respectively. When the attack time is over, a shiny, solid product has been obtained; it was characterized by SEM-EDS and AAS, confirming that it is metallic gold, with a purity of 100 and 99.9% according to the respective technique.