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

Background The NH 3 , a clean reductant, generated by the thermolysis of NH 4 VO 3 , is not effectively utilized in the conventional process of vanadium metallurgy. Additionally, the preparation process of V 2 O 3 is both long and costly. Ammonia recovery is essential to prevent environmental issues resulting from ammonia release. By direct thermolysis of NH 4 VO 3 and effectively utilizing of active NH 3 , it is possible to achieve the short flow and green process for the production of V 2 O 3 . Method In an open NH 3 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 NH 3 atmosphere, both ends of the tube furnace were sealed with flanges, and the initial atmosphere in the tube was pre-injection NH 3 . The products of NH 4 VO 3 thermolysis were characterized using various techniques, including XRD, FT-IR, ICP-OES, SEM, XPS, and TG. Significant finding The thermolysis process of NH 4 VO 3 with pre-injection of NH 3 under the sealed condition was a simulation of the continuous production process of V 2 O 3 using a rotary kiln in industrial production. The rational utilization of ammonia resulted in the reduce of energy consumption, extra reductant consumption, and significant NH 3 emissions compared to the traditional V 2 O 3 production process. It was observed that V 2 O 3 was easily obtained through the thermolysis of NH 4 VO 3 with pre-injection of NH 3 under the sealed condition at 600 °C for 3 h, using a dosage of NH 4 VO 3 ranging from 2 g to 10 g. During this process, the NH 4 VO 3 went through the phase transition as follows: NH 4 VO 3 →NH 4 V 3 O 8 →(NH 4 ) 0.38 V 2 O 5 →V 6 O 13 →VO 2 →V 4 O 7 →V 3 O 5 →V 2 O 3 , and the relevant characterization of products showed that the V 2 O 3 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 V 2 O 3 could be achieved in industry by partially improving the calcination process of NH 4 VO 3 in large-scale rotary kilns.