Copper extraction from printed circuit boards from mobile phones using a by-product of the fertilizer industry

The high concentration of recoverable materials in the printed circuit boards (PCBs) of cell phones makes reuse and recycling economically viable. Hydrometallurgy has been considered the best technology for recycling copper in printed circuit boards. The present work proposes a leaching process for extracting copper from printed circuit boards, with a solution containing fluosilicic acid (H₂SiF₆), which is a by‑product of the phosphate fertilizer industry. After a pre-treatment of the PCBs and a complete factorial design, the best condition for the extraction of copper from 5 g of PCB was 4 h of treatment at 25 °C, using 25% v/v H₂SiF₆ in the leaching solution. The electrodeposition performed, with the objective of recovering the largest amount of leached copper, had the best results in the following operational conditions: time of 30 minutes, concentration of 0.25 mol L^-1 of Na₂SO₄ (supporting electrolyte) and current of 2.5 A. The X-Ray Diffraction analyzes of the recovered material showed a diffractogram with diffraction patterns corresponding to copper oxides (Cu₂O) according to the JCPDS 78-2076 crystallographic record. In the Scanning Electron Microscopy (SEM) analysis of the recovered material, two different materials are observed, one structured (dark gray) and the other particulate (light gray), both with different morphologies. By X-ray Dispersive Energy (EDX) analysis, it was found that in the elementary composition of the structured material there is a higher percentage of copper (94.55%). (author)