Theoretical estimates and kinetic studies of leaching ores were found to be equally important. Additionally, during this period, the concept of species adsorption on mineral surfaces has evolved to become the dominant concept in the understanding of the fundamental mechanisms of the majority of reactions. This may have happened as a result of the fact that many scientists at the time were also involved in the mineral dressing industry and were therefore exposed to flotation theories. But as lattice flaws and minerals' semiconductivity became more well-known and their significance in extractive metallurgy became clear, it became necessary to explain the leaching procedures in the context of these modern notions. Semiconducting minerals can be divided into two categories: oxides like uranium and sulphides like copper, lead, and zinc. Sulphides are important in metallurgy.