【作者】 李晓军；

【导师】 谢兵；

【作者基本信息】 重庆大学 ， 冶金工程， 2011， 硕士

【摘要】 近年来,国际铁矿石价格逐年上涨,2011年4月品位在63%的铁矿石现货价格甚至超过了187美元/吨。相比较而言,国内铁矿石价格低廉,且运输成本低。为了缓解因进口矿价格上涨带来的压力,攀枝花成都钢铁公司（简称“攀成钢”）于2006年开展了高炉配加部分钒钛磁体矿工业试验并取得成功,不仅节约了成本,而且通过铁水提钒,实现了钒资源等有价金属的提取,培育了新的经济增长点。然而,由于高炉中钒钛磁铁矿配比较低,导致钒渣中V₂O₅品位仅为10%左右,对于这种低品位钒渣中的主要含钒物相—尖晶石相的生长规律及钒渣钙化焙烧机理研究,国内外鲜有报道,需要进行细致的研究。本文在分析攀成钢钒渣化学成分及物相结构基础上,采用实验与理论相结合的方法探究了钒铁尖晶石析出和长大的最佳热力学和动力学条件,得到了其结晶过程的表观活化能;同时,针对传统的钠化提钒法引起的环境污染问题,通过改变添加剂,即用CaO代替钠盐,达到了既降低环境污染又减少钠盐消耗的双重目的;并进一步系统研究了钒渣钙化焙烧—酸浸提钒工艺过程中各反应参数及主要组分对钒浸出率的影响,得到如下结论:①钒渣中尖晶石最佳生长温度为1523K左右;1523K保温5min,尖晶石平均粒径为9.83μm,随着保温时间的延长,尖晶石尺寸逐渐增大,100min时其平均粒径达到31.6μm,此时尖晶石生长基本完成;尖晶石生长过程可用JMAK方程近似描述,其表观活化能约为575kJ·mol^-1。②采用D. Turnbull模型计算得到钒渣中尖晶石最佳生长温度区间为1507-1557K,与实验结果吻合较好;当渣中CaO、SiO₂、TiO₂分别在1.80-3.80%、16.4-20.4%、10.5-14.5%范围内变化时,成分变化对尖晶石最佳生长温度区间影响较小,但对其结晶速率常数影响较大。③钒渣钙化焙烧过程主要包括三个阶段:300-500℃,Fe₂SiO₄等橄榄石相的氧化分解及渣中少量自由FeO的氧化;500-600℃,FeV₂O₄等尖晶石的分解氧化;600-900℃,钒酸钙的形成及辉石分解;焙烧过程中CaO可与V₂O₅反应生成CaV₂O₆、Ca₂V₂O₇、Ca₃V₂O₈等多种形式的钒酸钙。④钒渣钙化焙烧—酸浸过程中,CaO/V₂O₃在1.1左右时,钒浸出率达到69.95%,接近钠化焙烧工艺水平;SiO₂在20%左右时有利于提高钒浸出率;TiO₂不利于钒浸出率的提高。更多还原

【Abstract】 Recently, a sharp increase in the price of international iron ore can be seen, and even exceeded 187 dollars per ton for the iron ore grade of 63% in April, 2011. In contrast, the price and transportation cost of the domestic iron ore are relatively lower. Thus, some vanadium-titanium magnetite was added into blast furnace in order to alleviate the pressure from the rise of import ore price in Pangang group Chengdu steel co., LTD in 2006. Fortunately, it was successful and resulted in both reducing the production cost and extracting the valuable metals. However, the grade of V₂O₅ in vanadium slag is only about 10% due to the low ratio of vanadium-titanium magnetite in the blast furnace. The growth law of V-containing spinels and roasting mechanism of vanadium slag with low V₂O₅ concentration are seldom reported. Therefore, a systematic research on those is worthwhile to be conducted.On the basis of vanadium extraction from hot metal process of Pan-steel （Chengdu）, composition and phase structure of the vanadium slag were analyzed. Furthermore, thermodynamic and kinetic conditions which benefit the nucleation and growth of V-containing spinels were explored with both experimental and theoretical methods. The apparent activation energy of crystallization of the V-containing spinels was obtained. Moreover, CaO was treated as a new kind of additive to take the place of sodium salt and it contributed to reduce the environmental pollution as well as the consumption of sodium salt. Effect of reaction parameters and main components on the vanadium leaching ratio in the process of calcification-roasting and acid leaching was discussed. The main conclusions are as follows:①The best temperature which benefits the growth of spinels is around 1523K. The mean diameter of the spinels is 9.83μm when the holding time is 5 minutes, and it increases with the prolongation of holding time. The spinels growes completely and its mean diameter reaches 31.6μm when being held for 100 minutes. The isothermal growth process of spinels can be approximately illustrated by the JMAK equation. The apparent activation energy is obtained as 575kJ·mol^-1.②The best temperature interval which benefits the nucleation and growth of spinels is 1507-1557K calculated by D. Turnbull model and it shows a good agreement with the experimental data. No significant change in the best temperature interval can be seen when the contents of CaO、SiO₂、TiO₂ is respectively in the range of 1.80-3.80%、16.4-20.4%、10.5-14.5% in vanadium slag. But the effect of the composition on the crystallization rate constant is relatively remarkable.③The calcification-roasting process of vanadium slag can be divided into three different overlapping stages. Specifically, they are the oxidative decomposition of olivine phases and oxidative of seldom free FeO at 300-500℃, oxidative decomposition of spinel phases such as FeV₂O₄ at 500-600℃, and the formation of calcium vanadate with the decomposition of pyroxene at 600-900℃.The various calcium vanadate namely CaV₂O₆, Ca₃V₂O₈, CaV₃O₇ would formed between CaO and V₂O₅.④The vanadium leaching ratio could reaches 69.95% when the CaO/V₂O₃ is controlled at around 1.1 during the process of roasting and acid leaching of vanadium slag. The content of SiO₂ round 20% can be beneficial for improving the leaching ratio of vanadium. High concentration of TiO₂ in vanadium slag shows a negative effect on the leaching ratio of vanadium.更多还原