Abstract: Vanadium-removal slags of crude TiCl4 contain vanadium of 2% to 5%, indicating high recycling value. In order to realize the low cost recovery of vanadium resources from vanadium-removal slag, a new process of direct roasting, ammonium salt leaching, precipitation of vanadium to prepare NH4VO3 from vanadium-removal slag was proposed. And the related conditions tests were carried out focusing on the effects of roasting temperature, NH4HCO3 dosage, leaching temperature and leaching time on vanadium extraction. The results showed that: ① After roasting at 650 ℃ for 150 min, the main phases of the roasting samples are rutile TiO2, anatase TiO2, Al2O3, V2O5 and SiO2, and the vanadium oxidation rate reaches 78.12%. The low- cost extraction of vanadium could be realized by ammonium salt leaching. ② The optimum leaching conditions of roasted samples were determined as follows: dosage of NH4HCO3 of n(NH4+)/n(V) =2, ratio of liquid to solid of 5 mL/g, leaching temperature of 80 ℃, leaching time of 30 min. Under the above conditions, the leaching rate of vanadium could reach 76.65%, and the concentration of vanadium of leaching solution is 5.71 g/L. After circulating leaching for four times, the concentration of vanadium increased to 19.66 g/L. The high concentration leaching solution could directly precipitates vanadium to obtain NH4VO3 product with purity above 99%, which meets the requirements of standard Grade I product (YS/T 1022—2015). XRD analysis further confirms that it has high purity. The research results can provide technical support for the short process recovery of vanadium resources from vanadium-removal slag.

Key words: vanadium-removal slag, short process, oxidizing roasting, ammonium salt leaching, condition test, NH4VO3