Alkaline leaching of vanadium from calcified roasting residue of low-vanadium slag

摘要

By virtue of the combination of calcified roasting and alkaline leaching,recovery of vanadium from low-vanadium slag was studied in this paper.The technical processes of calcified roasting and alkaline leaching were also described in detail.With thermodynamic analysis of the roasting process,the type of roasting process additives,roasting time,and roasting temperature were also did a detailed study.Through a series of experiments,the process parameters of the leaching process had been studied,such as leaching time,leaching temperature and leaching concentration.By XRD,SEM,AAS and other tests,the roasting residue,leaching residue and leach solution were analyzed deeply.The results showed that when adding 8％CaCO3,roasting temperature of 950°C and holding time of 3h were found to be the best conditions for roasting,the conversion was up to 71％,and vanadium was mainly in form of CaV2O7 after roasting.With 15wt％ NH4HCO3 as leaching agent,leaching temperature was 80°C and leaching time was 3h,alkali leaching rate was the highest,which was up to 69.2％.This new method overcame the shortcomings of traditional method,such as pollution and long process,which could be considered as a new operational method of recovery of vanadium.