The recovery of molybdenum from acid solution using potassium ferrocyanide

Abstract A process has been devised for the recovery of molybdenum from a concentrated acid solution utilizing the well known reaction between molybdates and a soluble ferrocyanide. It is shown that the product of this reaction is molybdenyl ferricyanide (MoO2)3[Fe(CN)6]2. This compound is roasted in air to give a mixture of ferric and molybdic oxides, which can be separated by ammonia solution or, alternatively, it is converted to MoS3 by acidifying the solution obtained by dissolving it in yellow ammonium sulphide. Investigations into the effect of ammonia on the molybdate‐ferrocyanide reaction are described and it is shown that ammonium molybdate will react with potassium ferricyanide.