Recovering metals from motherboard and memory board waste through sulfuric leaching

Abstract

Printed circuit boards represent a source of urban mining for the reuse of resources in a circular economy. The number of metals in these boards can vary according to the model, year of manufacture, and function, making these scraps a complex residue for the application of recovery routes. In the present study, the leaching process was evaluated as an alternative to the magnetic separation step of the current hydrometallurgical routes for the recovery of iron and copper in these waste in which recovery of the metals present was carried out. The first stage of the hydrometallurgical route was leaching in sulfuric acid, for the recovery of iron. Subsequently, the copper recovery study was carried out, through the second stage of acid leaching in an oxidizing medium. The third stage was carried out in a nitric medium for the solubilization of the remaining metals. After using the same solid/liquid ratio for the solubilization of the metals present in the two types of boards, it was found that for the board with the highest concentration of metals that this ratio should be changed for greater extraction results. The percentage of leaching for the motherboard samples increased (to about 98 wt%) together with the residue/acid ratio, and this showed that for each type of waste, according to its composition, the metal/acid ratio must be established for complete solubilization of the metals of interest. The recovery of this waste, depending on the type of scrap, can reach at least US$ 1,230,000.00 /t waste. © 2021