title: An advanced study on the hydrometallurgical processing of waste computer printed circuit boards to extract their valuable content of metals.
abstract: This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2M H2SO4 (98% w/v), 5% H2O2, 25 °C, 1/10 S/L ratio and 200 rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20 g/L of CS(NH2)2, 6g/L of Fe(3+), 0.5M H2SO4, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5 g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing.
authors.affiliation: Department of Industrial and Information Engineering and Economics, University of L'Aquila, Via Giovanni Gronchi 18, 67100 L'Aquila, Italy. Electronic address: ionelapoenita.birloaga@graduate.univaq.it.
authors.forename: Ionela
authors.initials: I
authors.lastname: Birloaga
authors.affiliation: Department of Physical Chemistry, "Babeş-Bolyai" University, Arany Janos 11, 400028 Cluj-Napoca, Romania.
authors.forename: Vasile
authors.initials: V
authors.lastname: Coman
authors.affiliation: Austrian Society for Systems Engineering and Automation, A-1140 Vienna, Gurkgasse 43/2, Austria.
authors.forename: Bernd
authors.initials: B
authors.lastname: Kopacek
authors.affiliation: Department of Industrial and Information Engineering and Economics, University of L'Aquila, Via Giovanni Gronchi 18, 67100 L'Aquila, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vegliò
mesh_terms: D003300:Copper / Q000302:isolation & purification*; D059029:Electronic Waste / Q000032:analysis*; D006046:Gold / Q000302:isolation & purification*; D059027:Recycling / Q000379:methods; D012834:Silver / Q000302:isolation & purification*; D013890:Thiourea / Q000737:chemistry*; D018505:Waste Management / Q000379:methods*
chemical_list: D012834:Silver; D006046:Gold; D003300:Copper; D013890:Thiourea
keywords: Copper; Oxidative leaching; Precious metal; Thiourea cross leaching; Waste computer printed circuit board