Processing copper–vanadium precipitate formed from crude TiCl4 in titania and titanium sponge production

Copper wire is used to remove vanadium from crude TiCl4 in titania and titanium sponge production which produces a copper–vanadium precipitate. The recovery of copper and vanadium from this precipitate was studied. Experiments found that the precipitate can be naturally oxidized by stacking for one month in air, converting > 90% metallic copper contained in the original precipitate into CuCl2·2H2O, Cu2Cl(OH)3 and Cu2(OH)3Cl. The copper oxy-chlorides were easily converted to Cu(OH)2 by stirring in dilute NaOH at pH 11 and 80 °C under a liquid-to-solid ratio of 4:1. When the pH was lowered to about pH 2.5 by sulfuric acid, iron, titanium and vanadium oxides remained in the first acid leach residue and copper was selectively leached into solution. By evaporating and cooling the leach solution, a product of CuSO4·5H2O with 99.7% purity was obtained.To recover the vanadium, the filter cake was roasted with Na2CO3 at 700 °C for 3 h under the stoichiometric proportion of 2.5 for V. The calcine was then leached with water at 70 °C and NH4VO3 was precipitated by the addition of NH4Cl. Calcination of NH4VO3 at 550 °C for 2 h produced V2O5 with a purity of 98.6%. After vanadium recovery, the residue was leached once again with sulfuric acid and the total recoveries of copper and vanadium were 98.6% and 95.7% respectively.