Short flow and green process for the production of V2O3 powder via ammonia reduction method

Abstract

BackgroundThe NH3, a clean reductant, generated by the thermolysis of NH4VO3, is not effectively utilized in the conventional process of vanadium metallurgy. Additionally, the preparation process of V2O3 is both long and costly. Ammonia recovery is essential to prevent environmental issues resulting from ammonia release. By direct thermolysis of NH4VO3 and effectively utilizing of active NH3, it is possible to achieve the short flow and green process for the production of V2O3. MethodIn an open NH3 atmosphere, one end of the flange was connected to the liquid ammonia gas cylinder, while the other end was connected to the tail gas absorber. Furthermore, in a closed NH3 atmosphere, both ends of the tube furnace were sealed with flanges, and the initial atmosphere in the tube was pre-injection NH3. The products of NH4VO3 thermolysis were characterized using various techniques, including XRD, FT-IR, ICP-OES, SEM, XPS, and TG. Significant findingThe thermolysis process of NH4VO3 with pre-injection of NH3 under the sealed condition was a simulation of the continuous production process of V2O3 using a rotary kiln in industrial production. The rational utilization of ammonia resulted in the reduce of energy consumption, extra reductant consumption, and significant NH3 emissions compared to the traditional V2O3 production process. It was observed that V2O3 was easily obtained through the thermolysis of NH4VO3 with pre-injection of NH3 under the sealed condition at 600 °C for 3 h, using a dosage of NH4VO3 ranging from 2 g to 10 g. During this process, the NH4VO3 went through the phase transition as follows: NH4VO3→NH4V3O8→(NH4)0.38V2O5→V6O13→VO2→V4O7→V3O5→V2O3, and the relevant characterization of products showed that the V2O3 obtained was qualified. These experimental results were of great significance to the industrial practice of vanadium metallurgy. Based on these results, short flow and green process of V2O3 could be achieved in industry by partially improving the calcination process of NH4VO3 in large-scale rotary kilns.