China Nonferrous Metallurgy

The blank-roasting process of vanadium slag is a new method in the field of vanadium extraction from vanadium slag. It is of great significance to clarify phase variation characteristics to construct and improve the phase evolution mechanism of vanadium slag in roasting process. In this paper, starting from the phase content, morphology and occurrence of vanadium element that were easily neglected in previous phase study of vanadium slag, the variation characteristics of main phase in blank-roasting stage of vanadium slag were analyzed by equipments of mineral analyzer, XRD and SEM. The results showed that: vanadium spinel, fayalite and hedenbergite were gradually oxidized and decomposed with the increase of temperature, as well as a gradual reduction of their content. The content of manganese vanadate, iron oxide, pseudobrookite and other products increased gradually when the temperature rised. With the increase of temperature, vanadium slag, fayalite and hedenbergite were gradually transited from edge oxidation to internal oxidation until they were decomposed completely. And the oxidation and decomposition products of vanadium spinel were manganese vanadate, iron oxide and pseudobrookite, the oxidation and decomposition products of fayalite and hedenbergite were iron oxide and vitric. The vanadium element in vanadium slag mainly migrated from vanadium spinel to manganese vanadate, iron oxide and pseudobrookite. And the appropriate temperature for blank-roasting of vanadium slag was 900℃.