###### Abstract
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Mine Production (Tons)**} & \multicolumn{2}{c}{**Reserves**} \\ \hline  & 2022 & 2023 & (thousand MTs) \\ USA & 34,600 & 34,000 & 3500 \\ Argentina & \(-\) & \(-\) & 100 \\ Armenia & 7800 & 7800 & 150 \\ Australia & 277 & 500 & 690 \\ Canada & 1390 & 970 & 72 \\ Chile & 45,600 & 46,000 & 1400 \\ China & 106,000 & 110,000 & 5800 \\ Iran & 3700 & 3700 & 43 \\ Korea, North & 700 & 700 & NA \\ Korea, Republic of & 367 & 400 & 8 \\ Mexico & 15,500 & 15,000 & 130 \\ Mongolia & 3000 & 3100 & NA \\ Peru & 31,600 & 37,000 & 1500 \\ Russia & 1700 & 1700 & 1100 \\ Turkey & \(-\) & \(-\) & 52 \\ Uzbekistan & 1700 & 1700 & 21 \\ World total & 253,000 & 260,000 & 15,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Molybdenum world mine production and reserves. On the other hand, the main source for secondary molybdenum recovery is the catalysts used to desulfurize petroleum, petrochemicals, and coal\(-\)derived products [26; 27; 28]. Several hydro\(-\) and pyrometallurgical techniques have been proposed to extract molybdenum from low\(-\)grade concentrates. These techniques include hypochlorite, electro\(-\)oxidation, nitric acid leaching, alkali and pressure leaching, chlorination, and/or roasting with lime or soda ash. While hypochlorite and electro\(-\)oxidation procedures are efficient, they require significant amounts of chemical reagents, making this alternative economically inefficient [29; 30; 31; 32]. Other alternatives include nitric acid digestion, while alkali leaching injects oxygen gas. The high installation costs hinder this process's commercial viability. The chlorination process uses Cl\({}_{2}\) gas or a combination of chlorine and oxygen to convert molybdenum to chloride, oxychloride, and SO\({}_{2}\). Chlorine gas is poisonous and corrosive, which makes this alternative unfeasible for current industrial standards [33; 34; 35]. Finally, roasting molybdenum in the presence of lime or soda ash yields molybdenum to molybdate. Lime roasting produces insoluble water molybdate, which requires subsequent leaching, while soda\(-\)ash roasting produces water\(-\)soluble molybdate in a single stage. The soda ash method yields sodium molybdate [35]. Although this method is preferred because of its high efficiency and low gas emissions, high reagent consumption can be a significant problem for an eventual scaling\(-\)up of the processes [36; 37; 38]. For these reasons, from  
Figure 1: Molybdenite purification process to obtain Mo powders [23; 24; 25]. 2008 to 2012, the Chilean Nuclear Energy Commission (CCLEN) worked jointly with CODELCO to develop metallurgical processes to recover byproducts from copper mining operations to lower overall copper extraction operating costs [39]. As a result, CODELCO discovered average molybdenum concentrations of 50 mg/L in their copper leach solutions and concentrated them through the ion exchange technique, giving as a result molybdenum concentrates such as CaMoO\({}_{4}\). A speciation analysis of the conditions under which molybdenum is present in the aqueous solution is required to extract molybdenum from these solutions. Figure 2 shows that the major species for molybdenum at pH values greater than one are from the anion spectrum, and more precisely, the predominant species is Mo\({}_{\mathcal{O}}\)O\({}_{21}\)(OH)\({}_{3}\)\({}^{3-}\). However, it is crucial to note that molybdenum is extremely sensitive to pH fluctuations. If the pH of the copper leaching solution falls below one, the major molybdenum species becomes cation charged, reducing the efficacy of the chemical recovery process. Although the process was successful at the bench scale, the copper PLS contained high amounts of chloride in solution because of the presence of atacamite, Cu\({}_{2}\)Cl(OH)\({}_{3}\). This mineral, when leached, releases chloride ions into the solution, which compete with the molybdenum recovery process during adsorption.