*3.4. Environmental Assessment of the Scaled-Up Dismantling Process*

Considering that the process presented in the current study is in the early phase of development, the Biwer–Heinzle method was applied for its environmental impact assessment. According to the methodology described in the literature [30,44] the environmental factors were determined for six impact groups in the case of the input materials (Figure 4) and 11 impact groups in the case of the output materials (Figure 5) by allocating each of the materials streams to a class of toxicity (A = 1—highly toxic substances, B = 0.3—less toxic substances, C = 0—nontoxic substances). The general effect indices (GEIs) were also calculated by dividing the sum of environmental indices to the total mass indices obtained from the mass balance data (Table 9) of the dismantling process.

**Figure 4.** Environmental impact assessment for input streams.

It was found that the category "critical materials used" has the highest value due to the large amount of FeCl3 feed into the process. Additionally, FeCl3 is the main reason for the high chronic and acute toxicity of the input material stream. Among the other input streams, HCl and copper have the most important contributions to the results shown in Figure 4. The reason that copper surpasses other toxic components in the WPCBs, such as lead, is due to the fact that, even if it is less toxic than other components, it has the highest concentration. Similarly, for the output materials, chronic and acute toxicity remain important categories, but they are preceded by the "acidification potential" due to the depleted solution. Nevertheless, the GEIs values calculated for the input materials (0.064) is lower than for the output materials (0.039) indicating that the process diminishes the environmental impact of the WPCBs. Moreover, considering that both values are close to the minimum possible (0), it can be concluded that the dismantling process has an overall low environmental impact.

**Figure 5.** Environmental impact assessment for output streams.

#### **4. Conclusions**

The obtained results prove that the combined chemical–electrochemical process can be applied efficiently for the dismantling of different types of WPCBs with the parallel recovery of copper and regeneration of the leaching agent. As it was expected, in accordance with the redox equilibrium constants, all the metals, with the exception of gold, were dissolved during the leaching process. The experimental results demonstrate that the high purity (>99.95%) copper deposit can be produced with high current efficiency (72.69%) and low specific energy consumption (1.59 kWh/kg Cu). It is also important to note that the obtained copper deposits were compact and presented rough surfaces with larger nuclei and pyramidal growth, which is characteristic for copper deposition from chloride solutions. Modeling and simulating the conceptual recycling plant led to the conclusion that more than 90% of the copper can be extracted during the dismantling process by introducing a complementary step for the mechanical pretreatment of the boards, EC, and chips. It was also found that the dismantling of 1 kg of WPCBs requires 0.48 kWh, while the total specific energy consumption for copper production is 2.59 kWh/kg if the energy consumption of all process steps is considered. The overall energy balance revealed the possibility to use the process for a combined recycling–heating purpose, considering that it generates 47% more heat than the electrical power consumed. Based on the results of the environmental impact assessment, it can be concluded that the dismantling process can be performed not just with high technical performance but with low environmental impact as well. Still, further work is recommended to improve the technical performances and to assess the economic potential of the developed conceptual recycling plant.

**Author Contributions:** Conceptualization, S.F. and Á.I.-L.; methodology, S.F. and F.I.-L.; formal analysis, Á.I.-L.; investigation, F.I.-L., S.F. and Á.I.-L.; writing—original draft preparation, F.I.-L. and S.F.; writing—review and editing, S.F. and Á.I.-L.; supervision, S.F. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data sharing is not applicable to this article.

**Acknowledgments:** We are grateful for the administrative and financial support offered by the Babes-Bolyai University.

**Conflicts of Interest:** The authors declare no conflict of interest.
