含钒石煤脱碳焙烧过程温度变化规律及焙烧条件影响

Temperature variation of V-bearing stone coal during decarbonization roasting and effect of roasting conditions

含钒石煤是我国储量巨大的一种钒矿资源。对于含碳量高的石煤原矿,脱碳焙烧工艺能在提高钒浸出率的同时降低酸耗。对石煤脱碳焙烧过程的温度变化进行研究,避免高温烧结的同时还可利用其自身热量,这对提高焙烧过程热利用效率具有重要意义。本文在650℃、50 min、空气流量500 mL/min及20%O_(2)浓度的最佳焙烧条件下,对石煤悬浮焙烧的全过程进行系统分析和研究。在最初3.9 min内,样品迅速由室温升温至560.1℃;持续加热至10.3 min,白云石和高岭石分解,样品温度升至最高值741.5℃;燃烧结束后,样品温度回落,并稳定在622.5℃。这表明脱碳主要发生在最初的30 min内,石煤中碳质燃烧可将物料自身温度提高约120℃。基于此得到了含钒石煤脱碳焙烧过程的温度变化规律。因此,在石煤脱碳焙烧中应利用其温度变化规律,在避免高温和高氧引起的局部烧结的同时,利用自身燃烧热量,以提高焙烧效率和热利用率。

V-bearing stone coal is an important vanadium resource with huge reserves in China.For stone coal with high carbon content,the decarbonization process improves the vanadium leaching rate and reduces the acid consumption.Study of decarbonization temperature of stone coal is beneficial for avoiding high-temperature sintering and utilizing its heat,which is meaningful for efficient and energy-saving roasting.In this paper,the optimum roasting conditions of 650℃,50 min,500 mL/min,and 20%O_(2) were determined.Under the optimal decarbonization and leaching indicators,the entire process of stone coal suspension roasting was systematically analyzed and studied.Within the initial 3.9 min,the sample was rapidly heated to 560.1℃and continuing to 10.3 min,the sample temperature raised the highest peak of 741.5℃with the decomposition of dolomite and kaolinite.Finally,the sample was cooled to 622.5℃at the combustion end.This indicated that the decarbonization mainly occurs in the initial 30 min and the maximum temperature of shale is about 120℃higher than the final temperature caused by carbon combustion.In addition,intense combustion and local sintering caused by high temperatures and high oxygen content should be seriously avoided.