Phosphate-Intensified Alkali Leaching to Recover Molybdenum from a Volatilizing Residue

Volatilizing residues are commonly produced during the process of sublimating technical-grade molybdic oxide or oxidizing-volatilizing molybdenite concentrate, which contains a certain amount of Mo mainly existing in the form of molybdates. To achieve a deep Mo recovery from volatilizing residues, this work presented a new composite leaching reagent that consisted of sodium hydroxide (NaOH) and sodium phosphate (Na3PO4). It was found that the leaching of Mo in NaOH solution could be remarkably intensified with the addition of Na3PO4. Specifically, it showed that more than 90% of Mo was leached out from this material with 160 g/L NaOH and 20 g/L Na3PO4 at 95 °C for 120 min and liquid–solid ratio of 6 mL/g. Meanwhile, the rare earths were enriched in leach residue.