石煤提钒流化床焙烧条件优化

Optimization of fluidized bed stone coal roasting for vanadium leaching

针对现有石煤焙烧工艺的焙烧效果差、环境污染严重的问题,提出流化床两段石煤焙烧工艺,利用实验室流化床反应器研究了氧化焙烧、复合盐焙烧、添加剂与石煤的混合方式等对石煤流化床焙烧的钒浸出率的影响规律,比较了静态焙烧和流态化焙烧效果的差异,并对Ca O的固氯作用进行了考察。结果表明:流态化焙烧缩短了焙烧时间,降低了达到最大钒浸出率所需的反应温度;对比不同的石煤和添加剂的混合方式发现,与简单的物理混合法相比浸渍法不仅能提高钒的浸出率、缩短焙烧时间,而且能降低添加剂的使用量,具有明显的优势。在焙烧过程中加入Ca O明显减少了生成气体中的Cl含量,并进一步提高钒的浸出率。综合分析表明,采用浸渍法混合石煤与添加剂时,流化床焙烧的最佳实验条件为:焙烧时间45 min,添加剂用量6%,Ca O用量6%,此时的V2O5浸出率达到85.2%。

A newly proposed fluidized bed two-stage roasting is expected to upgrade the process of vanadium leaching from stone coal,for example,raising the vanadium leaching efficiency and reducing its possible environmental pollution. This article investigated the conditions of fluidized bed stone coal roasting in terms of its consequent leaching rate of V2O5 and Cl adsorption. In addition to reaction temperature and time,the tested conditions included also the reactor type between fluidized and fixed beds,roasting method between cases with and without an additive,addition method of additive between impregnation and physical mixing,and effect of Ca O on removing Cl from the generated gas. It is shown that fluidized roasting is more favorable to V2O5 leaching than static fixed bed roasting,which greatly shortens the roasting time and increases the leaching rate of V2O5. Comparing to the physical mixing,the impregnation of additive onto stone coal not only increases the vanadium leaching rate and shortens the roasting time for the maximum leaching rate but reduces also the necessarily required amount of additive. Adding Ca O in roasting sharply decreases the content of Cl-containing gas in the effluent gas of roasting to alleviate thus the environmental pollution. The optimal fluidized roasting conditions are shown to be impregnation of 6. 0% additive onto stone coal,at roasting temperatures ofabout 800 ℃,with the roasting time of 45 min,and the required Ca O is 6% of stone coal,the leaching rate reaches85. 2%.