钒铬渣两步氧化钠化焙烧分离钒、铬

Separation of Vanadium and Chromium from Vanadium-Chromium Slag by Two-Step Oxidizing and Na-Activation Roasting

通过计算反应Gibbs自由能对钒铬渣物相组成的氧化钠化过程进行理论分析,提出采用两步氧化钠化焙烧分离钒铬渣中的钒、铬。主要考察了焙烧温度、焙烧时间和苏打比对钒铬渣中钒、铬转浸率的影响。结果表明:钒铬渣氧化钠化焙烧提钒的最佳条件为焙烧温度830℃、焙烧时间2.5h和苏打比1.3,钒、铬的转浸率分别为88.6%和1.28%;提钒残渣氧化钠化焙烧提铬的最佳工艺条件为焙烧温度1100℃、焙烧时间2.5h和苏打比2.4,铬的转浸率大于80%。通过对渣相进行X射线衍射(XRD)和背散射电子(BSE)分析,钒铬渣焙烧熟料的主要物相为Fe_2O_3,FeTiO_3,Na_2Si_2O_5,NaVO_3和Cr_3O_8;进一步分析提钒残渣氧化钠化提铬机制,确定生成Na_2CrO_4的主要反应为CrO_3与Na_2Si_2O_5和NaFeO_2等中间产物发生的置换反应。

The oxidizing roasting process with soda of vanadium-chromium slag was analyzed by the calculation of reaction Gibbs free energy, and then the separation method of vanadium and chromium from vanadium-chromium slag by two-step oxidizing and Na-acfiva- ring was proposed. The influences of soda ratio, roasting temperature and roasting time on vanadium and chromium leaching conversion ratio were investigated. The results showed that the optimum conditions for recovery of vanadium from vanadium-c, hromium slag couhl be obtained at roasting temperature of 830 ℃, roasting time of 2, 5 h and soda ratio of 1.3, and the leaching conversion ratios of vanadium and chromium were 88, 6% and 1.28% , respectively, in the first step oxidizing and Na-activation roasting process. And the optimum conditions for recovery of chromium from extracted vanadium residue could also be obtained at masting temperature of 1100 ℃ , roasting time of 2.5 h and soda ratio of 2.4, and under these conditions, the leaching conversion ratio of chromimn was above 80% in the second step oxidizing and Na-activation roasting process. According to X-ray diffraction （XRD） and backscattered electron （BSE） analysis, the main phases of vanadium-chromium slag roasted chamotte were Fe203 , FeTiO3 , Na2 Si2O5, NaVO3 and Cr3O8. Farther analysis of the mechanisms of extraeting chromium from extracted vanadium residue confirmed that the main formation reaction of Na2CrO4 was the replacemem reaction between CrO3 and Na2Si2O5 , NaFeO2 , etc.