Leaching of Copper from Waste-Printed Circuit Boards (PCBs) in Sulfate Medium Using Cupric Ion and Oxygen

Abstract

In the present paper, the leaching of copper from printed circuit boards (PCBs) using sulfuric acid with Cu2+ and O2 is proposed. The effects of various process parameters such as agitation speed, temperature, the type and the flow rate of gas, initial Cu2+ concentration, and pulp density were investigated to examine the dissolution behavior of Cu from PCBs in 1 mol/L sulfuric acid. The kinetic studies were performed using the obtained leaching data. The leaching rate of Cu from PCBs was found to be higher on addition of Cu2+ and O2 to the leachant in comparison with the addition of O2 or both Cu2+ and N2 in the leachant. The leaching efficiency of Cu was found to be increased with increasing agitation speed, temperature, O2 flow rate, and initial Cu2+ concentration and decreasing pulp density. The 96% of Cu leaching efficiency was obtained under the following conditions: sulfuric acid concentration, 1 mol/L; temperature, 90 °C; agitation speed, 600 rpm; pulp density, 1%; initial Cu2+ concentration, 10,000 mg/L; and O2 flow rate, 1000 cc/min. The leaching data and analyses indicate that the Cu leaching from PCBs followed the reaction-controlled model satisfactorily and determined that the activation energy was found to be 23.8 kJ/mol. Therefore, these results indicate that the sulfuric acid solution with Cu2+ and O2 as a mild leach medium without strong oxidants such as HNO3, H2O2, and Fe3+ is valid for Cu leaching from PCBs.

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

“…In addition to the kinetics study performed, this showed that process is governed by a mixed control (diffusive and chemical), as in Figure 5 and Figure 7 . It was evident that the hydrodynamic and thermodynamic variables affected the leaching of copper, while the value of the activation energy (E a ) was 25.78 kJ/mol, corroborating the mixed chemical–diffusive control for the leaching kinetics, which was quite similar (23.8 kJ/mol) to that obtained during the leaching of Cu from WPCBs in sulfate medium using cupric ions and oxygen [ 37 ]. This confirmed that the studied system studied is valid for leaching the Cu contained in these kind of residues, without the need to add oxidants such as HNO 3 , H 2 O 2 , Cu 2+ , or Fe 2+ .…”

“…However, for the leaching of Cu, no work has been carried out using this leaching system. The most closely related works on the leaching of Cu have used ammonium and Cu 2+ , or ammonia−ammonium sulfate [ 37 , 42 ]. For this reason, the present work is of importance due, principally, to the use of a non-toxic reagent, which was used directly without the addition of an oxidant like HNO 3 , H 2 O 2 , O 3 , Cu 2+ , or Fe 2+ .…”

“…Some researchers have used nitric acid and obtained recoveries of up to 99.9% without dissolution of the gold involved and also using oxidants such as ozone or H 2 O 2 [ 32 , 33 , 34 , 35 ]. Others have used sulfuric and hydrochloric acids to recover Cu from WPCBs and have had adequate results [ 36 , 37 , 38 ].…”

“…As is known, the thiosulfate–oxygen system has been shown to leach precious metals such as Au and Ag. However, no work have been carried out to leach Cu from WPCBs with the above-mentioned system, while there has been some work carried out on leaching Cu using ammonium and Cu 2+ , or ammonia–ammonium sulfate [ 37 , 42 ]. For this reason, the present work is of importance due principally to the use of a non-toxic reagent which will be used directly without the addition of an oxidant such as HNO 3 , H 2 O 2 , O 3 , Cu 2+ , or Fe 2+ .…”

Box-Behnken Optimization and Theoretical Study for Copper Recovery from Scrap Laptop Computer Printed Circuit Board by Malonic Acid and Hydrogen Peroxide

“…While significant work has been reported on the hydrometallurgical recovery of metals from PCBs using HNO3, HCl, H2SO4, and aqua-regia, aqua regia, is popular for the determination of the initial Cu content of PCB samples and has been observed to demonstrate excellent efficiency in Cu leaching than other leach solutions [38][39][40]. It was important to determine the initial Cu content of the PCB to have a reference to which the efficiency of the test leach solution (mixture of malonic acid and H2O2) can be compared.…”