ABSTRACT

In this study, a new vanadium extraction process from vanadium titano-magnetite(VTM) featuring calcification roasting and (NH₄)₂C₂O₄ solution leaching has been proposed. Compared with the traditional sodium roasting, the calcification roasting can avoid the production of waste gas and the sodium free tailings can be used for iron recovering by steel-making. However, the leaching rate of (NH₄)₂C₂O₄ was lower than that in sodium salt roasting-waterleaching. The reaction kinetics and mechanism of these two process were studied and compared in detail. It was found thatCaV₂O₆was formed during calcification and the porous structure of calcine facilitated the mass transfer. In the subsequent (NH₄)₂C₂O₄ leaching, theCaC₂O₄was formed and it would precipitate at the calcine particle surface and pores, which hindered the vanadium leaching. The leaching kinetics study showed that the diffusion through the solid product layer was the rate-determiningstep. Mechanical activation method was proposed to improve the leaching reaction kinetics in this work. It has been evident to be an effective method to intensify the leaching process. Under the optimal roasting and leaching conditions, the vanadium leaching rate could reach 81%, which was similar to that of the sodium salt roasting process. This is a promising alternative process for vanadium extraction from high grade VTM.

摘要

本研究提出了一种钙化焙烧和(NH ₄ ) ₂ C ₂ O ₄溶液浸出的钒钛磁铁矿(VTM)提钒新工艺。与传统的钠化焙烧相比，钙化焙烧可以避免废气的产生，并且无钠尾渣可用于炼钢回收铁。_{但(NH 4} ) ₂ C ₂ O ₄的浸出率低于钠盐焙烧-水浸法。对这两个过程的反应动力学和机理进行了详细的研究和比较。结果发现CaV ₂ O ₆在钙化过程中形成，并且煅烧物的多孔结构有利于传质。在随后的(NH ₄ ) ₂ C ₂ O ₄浸出中，CaC ₂ O ₄形成并沉积在煅烧颗粒表面和孔隙中，阻碍钒的浸出。浸出动力学研究表明，通过固体产物层的扩散是速率决定步骤。在这项工作中，提出了机械活化方法来改善浸出反应动力学。显然这是强化浸出过程的有效方法。在最佳焙烧浸出条件下，钒浸出率可达81%，与钠盐焙烧工艺相近。这是从高品位 VTM 中提取钒的一种有前途的替代工艺。