Extração de cobre em placas de circuito impresso de celulares empregando subproduto da indústria de fertilizantes

Abstract

The high concentration of recoverable materials in printed circuit boards (PCBs) from cell phones makes their reuse and recycling economically feasible. Hydrometallurgy, characterized by the dissolution of metals in alkaline or acidic medium, is considered the most appropriate technology for recycling copper in printed circuit boards, with the main research focus being the search for improved leaching agents. The present work proposes the development of a copper extraction process using PCBs with a leaching solution containing, in addition to hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), fluorosilicic acid (H2SiF6) which is a by-product of the Phosphate fertilizer industry. The PCBs were initially subjected to pre-treatment for removal of electronic components and volume reduction. The experiments were carried out in accordance with a factorial experimental design, to obtain adequate operational parameters for the process. The best condition for the extraction of copper from 5 grams of cell phone PCBs was 4h of treatment at 25°C using 25% H2SiF6 in the solution composition. The electrodeposition was proposed, with the objective of recovering the largest quantity of copper (Cu(II)) leached, the best condition being obtained in 30 min, 0.25 mol L-1 of sodium sulphate (Na2SO4) and 2.5 A. The X-ray diffraction analyses of the recovered material showed a diffractogram with peaks corresponding to copper oxides (Cu2O) according to the crystallographic data sheet JCPDS 78-2076. To characterize the recovered material, Scanning Electron Microscopy (SEM) was used, where two different materials are observed, one structured (dark gray) and another (light gray), both with different morphologies. Through the X-ray Dispersive Energy Analysis (EDX), it was found that in the elemental composition of the structured material there is a higher percentage of copper (94.55%) than in the particulate form (77.44%).