Concentrating of vanadium oxide in vanadium rich phase(s) by addition of SiO2 in converter slag

The focus of the present work was to examine whether vanadium rich phase(s) could be obtained in converter slags having high V2O5 contents. Slags from SSAB Oxelosund, Sweden and Ma Steel, China were studied. Despite of the composition difference, slags from both industries were found to contain essentially the same phases after heat treatment. No vanadium rich phase could be obtained by only heat treatment of the slag. The addition of 12 mass%SiO2 changed substantially the phase relationships in the slags. Two vanadium rich phases were detected in the slag samples with SiO2 addition. One of the phases was expected to be a solid solution of 3CaO.V2O5 and 3CaO.P2O5 with < 3 mass%SiO2 dissolved. The other vanadium rich phase had high SiO2 content. About 67-68 mass% vanadium was captured by the vanadium rich phase(s) after the treatment. The present finding would open up new opportunities for recovery of vanadium from converter slags.