Method for preparing vanadium trioxide from sodium-vanadate salt

The invention relates to a method for preparing vanadium trioxide from sodium-vanadate salt. The method comprises the following steps of using the sodium-vanadate salt as a raw material, reducing the sodium-vanadate salt at a temperature of 125 to 629 DEG C through a carbon-containing reducing gas, so as to obtain reduzate consisting of the vanadium trioxide and sodium carbonate, adding water in the reduzate to dissolve the sodium carbonate in the reduzate, then filtering an obtained first mixture, afterwards, water-scrubbing and oven-drying a filter cake to obtain a vanadium trioxide product, acidifying dissolution liquid by using CO2, and crystallizing, separating and recovering the sodium-vanadate salt in the dissolution liquid. By using the method, not only is the production technological route for obtaining the vanadium trioxide from the sodium-vanadate salt greatly simplified, but also the production cost of the vanadium trioxide is obviously decreased; the generation of waste water and waste residue are effectively avoided in a technological process. The method has the advantages of short technological route, low processing cost, good product quality, no generation of the waste water and the waste residue, high efficiency, environment friendliness and the like, and is suitable for the industrialized production of the vanadium trioxide.