**Acknowledgements**

The authors are grateful for the United Arab Emirates University (Office of the Deputy Vice Chancellor for Research & Graduate Studies) who funded this work under Fund number G00003084, 2019/2020.

#### **Appendix A**

Note that reactions R8, R8\*, R9, and R12 presented in **Table A.1** (for H2SO4) are common in all acid-leaching processes using HNO3 (**Table A.2**), HCl (**Table A.3**), and HClO4 (**Table A.4**)


#### **Table A.1.**

*Calculated ΔHR and ΔGR at 30°C for the reactions of the main SPL constituents when leached with H2SO4 solution.*

#### *Waste Material Recycling in the Circular Economy - Challenges and Developments*


*a Stands for reactions involving HF(g) or HCN(g).*

*b Stands for alternative spontaneous reaction.*

*c <sup>Δ</sup>GR at T <sup>&</sup>gt; 100°C. <sup>d</sup>*

*ΔGR at T > 180°C.*

#### **Table A.2.**

*SPL reactions with HNO3 and their ΔHR and ΔGR at 30°C.*


#### **Table A.3.**

*SPL reactions with HCl(g) and their ΔHR and ΔGR at 30°C.*


*A Zero-Waste Process for the Treatment of Spent Potliner (SPL) Waste DOI: http://dx.doi.org/10.5772/intechopen.99055*


*Stands for reactions involving HF(g) or HCN(g).*

*b Stands for alternative spontaneous reaction.*

*c Stands for HClO4(ia). <sup>d</sup>*

*<sup>Δ</sup>GR at T <sup>&</sup>gt; 240°C. <sup>e</sup> ΔGR at T > 225°C.*

*f*

*<sup>Δ</sup>GR at T <sup>&</sup>gt; 550°C. <sup>g</sup> ΔGR at T > 350°C.*

#### **Table A.4.**

*SPL reactions with HClO4(g) and their ΔHR and ΔGR at 30°C.*


#### **Table A.5.**

*Calculated ΔHR and ΔGR at 30°C for other potential reactions taking place during the SPL leaching process.*
