An efficient utilization of high chromium vanadium slag: Extraction of vanadium based on manganese carbonate roasting and detoxification processing of chromium-containing tailings.

A novelty roasting method with manganese carbonate (MnCO3) as additive was carried out to separate and recover vanadium from high chromium vanadium slag (HCVS) efficiently. Vanadium tailings containing chromium was detoxified by carbon reduction and smelting to form Fe-Cr alloy. The whole process of HCVS utilization was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 89.37% of vanadium and 0.10% of chromium was leached when MnCO3 was added to HCVS at the mole ratio of MnO in MnCO3 and V2O3 in HCVS (n(MnO)/n(V2O3)) of 2.0 and heating at 850 °C for 120 min, then leached under the pH value at 2.5. 99.19% of vanadium was precipitated by (NH4)2SO4 and V2O5 with a purity of 99.28% was prepared. More than 84% of manganese addictive was recovered after manganese precipitation by carbonization with CO2 discharged from manganese carbonate roasting, which could be used as the raw addictive for roasting. The wastewater after vanadium and manganese extraction could be circulated as leaching medium. Three circulation routes realized the closed-circuit circulation of raw materials and products, saving the production costs and avoiding the environmental pollution. Fe-Cr alloy with 67.35% of Fe and 13.28% of Cr was obtained from chromium-containing vanadium tailings, which could be returned to the steelmaking process.