Leaching of Copper Contained in Waste Printed Circuit Boards, Using the Thiosulfate—Oxygen System: A Kinetic Approach

Abstract

The present work is related to the treatment of crushed waste of printed circuit boards (WPCBs) from electrical and electronic devices (WEEE), carrying out the recovery of copper in solution. In the first stage, the studied material was characterized by AAS, SEM-EDS, and XRD. The results revealed significantly high amounts of copper (744.42 mg/g), compared with the rest of the metals present in the sample, mainly iron and zinc. In the second stage of the work, alkali dynamic leaching experiments were carried out in the S2O3−2− O2 medium, evaluating important kinetic variables in order to verify the controlling step of the system and adjust the data to a kinetic model. According to the results obtained from the various experimental tests executed, it was found that in the studied system of S2O3−2− O2, the leaching of copper was preferably adjusted to the model of spherical particles with a shrinking core finding a mixed chemical–diffusive control, with values of Ea = 25.78 kJ/mol and n = 0.22 (for the leaching reagent), indicating that the reaction was controlled by the oxygen transport to the solid–liquid interface and also by the chemical reaction in the surface of particles, obtaining up to 99.82% copper in solution.

Gold Leaching from Printed Circuit Boards Using a Novel Synergistic Effect of Glycine and Thiosulfate

“…During the leaching process, thiosulfate can self-decompose or reduce to S 0 , S 2− or S 2 O 3 2− , and the resulting derivatives can deposit on the Au to form a passivation layer [10]. A kinetic study related to Cu leaching from PCBs with thiosulfate has also been found to be the diffusion-controlled model [63].…”

“…process, thiosulfate can self-decompose or reduce to S 0 , S 2− or S2O3 2− , and the resulting derivatives can deposit on the Au to form a passivation layer [10]. A kinetic study related to Cu leaching from PCBs with thiosulfate has also been found to be the diffusion-controlled model [63]. The glycine system is unsuitable for agitated leaching systems due to having a low kinetic in Au leaching compared to that in cyanide [18].…”

A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate: A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals

“…In the following sections, the above hypotheses are discussed based on the experimental results. The dissolution reaction of gold in ammonium thiosulfate has been reported by many authors and is summarized as: (Equation ( 2)) [27,[29][30][31][32][33][34].…”

“…This may be interpreted by assuming the decomposition of thiosulfate due to the presence of an excess amount of dissolved oxygen. According to Rodriguez et al [33], an excess amount of dissolved oxygen favors the oxidation of thiosulfate and its complexation with Cu; oxygen causes the oxidation of Cu(I) to Cu(II), at the same time decomposing thiosulfate to form (S 2 O 3 ) 3 5− , sulfite(SO 3 2− ), sulfate(SO 4 2− ), and elemental sulfur(S) as shown in Equations ( 8) and ( 9) [34]. In addition, the rate of oxidation of Cu(I) to Cu(II) is slower than the reduction of Cu(II) by thiosulfate, which may result in the formation of Cu(I)-sulfide precipitates, thus causing a reduction in the sulfur concentration.…”

Processing of End-of-Life Materials and Industrial Wastes

“…Salinas-Rodríguez et al [ 18 ] authored a submission, entitled “Leaching of Copper Contained in Waste Printed Circuit Boards, Using the Thiosulfate—Oxygen System: A Kinetic Approach”. This research work is devoted to the treatment of crushed printed circuit board (PCB) wastes from electrical and electronic devices (WEEE), carrying out the recovery of copper in solution.…”