Application of thermal analysis to the rhenium recovery process from copper and molybdenum sulphides minerals

Rhenium production from copper and molybdenum sulphides involves the use of a pyrometallurgical process. In traditional pyrometallurgy processes, gases emissions produce unacceptable air pollution and damage the extractive metallurgy equipment, leading to high production cost. Due to the environmental disadvantages presented by the oxidizing roasting, in this paper the carbothermal reduction process application on molybdenum–copper sulphides with Re, is studied as a possible alternative. The main purpose of the study is to concentrate the element (Re) applying non-traditional process, with low operating costs and good environmental response avoiding polluting gases such as SO2. The concentrates were previously treated by an alkaline leaching process to remove impurities such as As, Se and Sb. These impurities are penalized and in addition they produce a calcine that is inefficient from an economic and a production point of view. The traditional production of Re involves Re oxide volatilization during the molybdenite processing, which is then condensed at low temperature to generate a dilute solution of a Re compound. The results show that Re was collected as metallic Re and in a form of a carbide compound avoiding Re2O7 volatilization and reducing total gases emissions in ≈ 36%.