Recovery of vanadium, potassium and iron from a spent vanadium catalyst by oxalic acid solution leaching, precipitation and ion exchange processes

A spent vanadium catalyst was leached in an oxalic acid solution to recover vanadium, potassium and iron. The effects of time, temperature, acid concentration, phase ratio and catalyst particle size were studied. The results showed that for a 180–250 μm catalyst leached for 4 h at 323 K in the presence of 2% oxalic acid solution at a liquid:solid ratio of 25:1, the extent of leaching of V, K and Fe was about 91%, 92% and 63%, respectively. Studies on the separation of vanadium from iron were conducted. The effect of pH on the concentration of the investigated compounds in post-leaching solution was presented. Additionally, separation of vanadium from such a solution was investigated by the ion exchange method. Three types of polymer strongly acidic ion exchangers were used. The ion exchange tests indicate that only potassium and iron were loaded from the post-leaching solution. On this basis a flowsheet for the proposed process of a complex utilization of spent vanadium catalyst is presented.