| Vanadium is an important strategic raw material.At present,about 60%of vanadium products in China are produced by leaching vanadium slag obtained from blast furnace ironmaking and converter steelmaking of V-Ti magnetite after sodium/calcification roasting.The roasting process consumes a lot of energy and emits harmful gas to pollute the environment seriously.It is significant to carry out direct acid leaching test of vanadium slag without roasting to realize efficient and clean recovery of vanadium slag.Thermodynamic calculation and E-pH diagram analysis of leaching process show that all the major phases in vanadium slag can be dissolved in acid theoretically,and vanadium mainly exists in the form of V3+,V2+,VO2+and VO2+when pH<1.5,while in the stable region of H2O,it mainly exists in the form of VO2+.Mechanical activation experiments show that the particle size decreases,the specific surface area increases,a large number of cracks appears in the surface,the XRD peak strength of vanadium chromium spinel decreases obviously with the increasing of activation time;When the activation time exceeds 240min,mineral particles begin to agglomerate and do not decrease.The direct sulfuric acid leaching experiment of vanadium slag indicates that most of the silicate minerals can be dissolved under atmospheric pressure;the reaction temperature,sulfuric acid concentration and liquid-solid ratio have the significant effect on the vanadium leaching.The optimal acid leaching experimental conditions obtained by BBD design of response surface were H2SO4 concentration 4.3mol/L,reaction temperature 90℃,liquid-solid ratio 9.8,leaching reaction time 9.3h and stirring speed 400rpm.Under the optimal condition,the vanadium leaching rate is 91.02%.The leaching kinetics test demonstrates that the apparent activation energy is 17.63kJ/mol and the leaching process is controlled by the mixed control of chemical reaction and interior diffusion,and the acid influence index was 1.06.Figure 34;Table 13;Reference 88... |
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