Processing molybdenum concentrates using low-temperature oxidizing-chlorinating roasting

The availability of applying oxidizing-chlorinating roasting with alkali metal chlorides to process the molybdenite concentrate, which is determined by a decrease in roasting temperature to 450°C and the formation of water-soluble molybdenum compounds during roasting, is shown. It is established that ∼60–75% molybdenum remains in ash in this case, while its remaining amount is chlorinated and distilled in the composition of chlorides and oxychlorides being completely caught in the settling chamber and absorbers. The chemism of processes occurring during the oxidizing-chlorinating roasting, which makes it possible to explain a decrease in the oxidizing temperature of molybdenite from 550–600 to 450°C, is described. Optimal modes of ash leaching with water and alkali solutions are determined; based on them, a functional production flowchart which includes oxidizing-chlorinating roasting with sodium chloride, two-stage leaching (aqueous and alkaline), and the dissolution of condensed molybdenum oxides and oxychlorides, is proposed to process molybdenite concentrates. This flowchart makes it possible to process certified molybdenite concentrates with the recovery of molybdenum into solutions no lower than 98%.