The alkaline leaching of molybdenite flotation tailings associated with galena

A method for the extraction of both Pb and Mo from molybdenite flotation tailings associated with galena is described. The flotation tailings were pre-roasted and then alkaline leached. The effect of temperature, initial concentration of sodium hydroxide solution, alkali to total calcine mass ratio, leaching time and stirring speed on the leaching of Pb and Mo were systematically investigated by experiment. Optimum conditions were identified as: pre-roasting at 600 °C for 1 h, alkaline leaching for 1 h at 130 °C with an alkali to total calcine mass ratio of 1.2:1, initial NaOH concentration 30%, and a stirring speed of 600 rpm. Under these conditions 98% of the Pb and 98% of the Mo in the flotation tailings were extracted.

► Pre-roasting-alkali leaching was used to treat molybdenite flotation tailings.
► Pre-roasting can improve the extraction percentage of Pb and Mo.
► Under optimum conditions Mo and Pb extractions as high as 98% were achieved.