Sadia Ilyas is currently working as an Assistant Professor in the Department of Chemistry, University of Agriculture Faisalabad, Pakistan. After receiving her M.Phil. and Ph.D. in Inorganic Chemistry from Bahauddin Zakariya University (Multan) and University of Agriculture (Faisalabad), respectively; she served in China as Senior Researcher at the School of Chemical Engineering and Pharmacy (Wuhan) and in Korea as Postdoctoral fellow at Korea Institute of Geoscience and Mineral Resources, and in Pakistan as Assistant Professor at GC University Faisalabad. Besides the academic lecture in Inorganic Chemistry and hydrometyallurgy, her research deals with hydrometallurgical exploitation of metals from primary and secondary sources using microbial and chemical activities. She has published more than 30 research articles in peer-reviewed international journals and also author in three books, nine contributed book chapters, text books and laboratory manuals. Jae-chun Lee is currently Distinguished Principal Researcher in the Mineral Resources Research Division at the Korea Institute of Geoscience and Mineral Resources (KIGAM) and an adjunction professor in the Department of Resources Recycling at the Korea University of Science & Technology. Dr. Lee received his B.S. in metallurgical engineering, M.S. and Ph.D. in Hydrometallurgy from Hanyang University, Korea. His research deals with leaching, separation and purification of metals from primary and secondary resources. His current research focuses on the recycling of valuable metals from urban mines by hydrometallurgical routes. Dr. Lee has published around 300 research articles in several international peer-review journals and contributed in three book chapters.