*3.2. Experimental Dismantling Process of WPCBs*

The results presented in Table 6 prove that the combined chemical–electrochemical process leads to the complete dismantling of the WPCBs samples, leading to different material fractions. It can be observed that the obtained fractions can be easily separated due to the major differences in physical characteristic, such as size and density.


**Table 6.** Material fractions resulted from the dismantling process.

The obtained material fractions still have in their composition undissolved metals, considering that, in the dismantling process, only the metals, which were accessible to the leaching solution, from the surface of the WPCBs were dissolved. To determine their metallic composition, they were grounded to a fine powder and treated with aqua regia to determine the metallic composition, which is presented in Table 7. It can be noticed that, for all the samples, the plastic fractions do not contain metals, which means that all the pins were dissolved. Similarly, the boards contain only copper in a relatively high concentration, and this material can be further processed for high purity copper recovery. As for the other two solid fractions, all the metals are present with the remark that they have high Au and Ag concentration, especially in the case of the obtained sludge. Additionally, Table 7 indicates that almost 70% of the metals present in the initial samples were dissolved during the dismantling process, and the major component is Cu, which represents, on average, 50% of the dissolved metals.

**Table 7.** The metallic composition of the different fractions obtained in the dismantling process.


This is the main reason why the leaching solution is suitable for high purity copper production simultaneously with the regeneration of the leaching agent and dismantling of the WPCB samples. Considering that the cathodic deposits were obtained at the same current density and flow rate and a similar solution composition, they showed very similar, almost identical, morphological properties and elementary composition. According to the composition analysis, in all the experimental studies, the cathodic deposit contains more than 99.95 wt.% copper, the only impurity being Sn. The elementary analysis results presented in Figure 1 confirm that the developed process leads to the recovery of a high purity copper deposit. It is also important to note that the obtained copper deposits were compact, which is sustained by the characterization made by SEM.

**Figure 1.** EDAX spectrum of the copper deposit.

In addition, the SEM images from Figure 2 show that the copper deposit presents rougher surfaces with larger nuclei and pyramidal growth, which is characteristic for copper deposition from chloride solutions in accordance with the literature data [43].

**Figure 2.** SEM images for the copper deposit at magnitude: ×500 (**a**); ×2500 (**b**).
