Transformation behavior of calcium vanadate and manganese vanadate in CaO-V2O5-MnO2 system during calcification roasting of vanadium slag
(1. School of Metallurgy, Northeastern University, Shenyang 110819, China;
2. Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang 110819, China;
3. Liaoning Key Laboratory for Metallurgical Sensor and Technology, Shenyang 110819, China)
2. Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang 110819, China;
3. Liaoning Key Laboratory for Metallurgical Sensor and Technology, Shenyang 110819, China)
Abstract: A simplified CaO-V2O5-MnO2 system was established to qualitatively and quantitatively investigate the transformation behavior of vanadates. The results demonstrated dynamic transformations between calcium vanadate and manganese vanadate as n(CaO)/n(V2O5)/n(MnO2) ratios and roasting temperatures varied. When MnO2 was incrementally added with n(CaO)/n(V2O5) of 2, some Ca2V2O7 converted to Mn2V2O7. The mass of vanadium as calcium vanadate consistently exceeded that as manganese vanadate. Conversely, when CaO was gradually added with n(MnO2)/n(V2O5) of 2, Mn2V2O7 tended to transform into Ca2V2O7 and Ca3V2O8. The affinity of vanadium for calcium was higher compared that of vanadium for manganese. The specific type of calcium vanadate formed depended on both n(CaO)/n(V2O5)/n(MnO2) values and roasting temperatures, while manganese vanadate remained predominantly as Mn2V2O7. The influence of roasting temperature on the conversion between calcium vanadate and manganese vanadate was minimal. At n(CaO)/n(V2O5)/n(MnO2) of 2/1/2 and temperatures ranging from 650 to 850 °C, the mass ratio of vanadium present as calcium vanadate to manganese vanadate stabilized at approximately 2.
Key words: transformation behavior; CaO-V2O5-MnO2; calcium vanadate; manganese vanadate; vanadium slag; calcification roasting