Study On The Reduction Roasting Of Cr-bearing Residue

There are abundant vanadium-titanium magnetite resources in our country. Large amounts of vanadium tailings which are rich in valuable metal elements such as iron, chromium, etc. were discharged in the melting process Not only the serious environmental problems caused by stockpiling of vanadium tailings could be solved effectively, but also the stress of chromium resources shortage cound be mitigated if the recyle of valuable metal elements is realized.In this thesis, experiments of pellet reduction roasting were carried, using Cr-bearing vanadium tailings as raw material on the basis of former research. Phase variation and the migration and concentration regularity of valuable metal elements such as iron and chromium in the process of reduction were investigated by means of SEM analysis, X-ray diffraction analysis and chemical analysis combined with thermodynamic analysis. The conclusions based on the experimental conditions were summarized as following:(1) The yielding rate of Fe, Cr, Mn and V increased gradually at first and then decreased with the increase of temperature, which reached the maximum value at 1400??The yielding rate at 1400? were 93.7%,96.8%,83.5% and 86.4% for Fe, Cr, Mn and V respectively. The yielding rate of Ti achieved its maixma 75.6% at 1300?.(2) The yielding rate of Fe, Cr, and V increased gradually at first and then decreased with the improvement of alkalinity. The yielding rate were 97.6%,86.8% and 86.4% respectively when the basicity is 1.0. The yielding rate of Mn maintained above 80% when the basicity was between 0.5 and 1.0, while the yielding rate of Ti had no significant correlation with basicity.(3) Fe and Cr mainly enriched in metallic iron and ferrochromium alloy during the pellet reduction process of vanadium tailings and their enrichment degree increased gradually with the reduction temperature increased, the time prolonged and the basicity improved. Mn migrated to ferromanganese and enriched in it with the temperature increased. V-Ti carbide was the main V-concentrating phase and enterd into magnetic products associated with metal phase in the course of magnetic separation. Ti migrated from perovskite to V-Ti carbide gradually with the rise of temperature and enriched in V-Ti carbide when the temperature was above 1400? which mostly entered into the magnetic products during magnetic separation.