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以湖北某地含钒石煤为原料,研究了空白焙烧-加助浸剂酸浸提钒工艺,并考察了在浸出时间为4 h,液固比:1.5∶1.0的条件下,焙烧温度、焙烧时间、硫酸浓度、助浸剂用量、浸出温度对钒浸出的影响,列出了白云母在浸出过程中与酸发生的主要反应,计算了各反应不同温度下的ΔGθT,并绘制了ΔGθ-T的关系图。研究表明:焙烧温度700℃,焙烧时间1 h,硫酸浓度4 mol.L-1,含氟助浸剂用量为原矿质量的5%,浸出温度为98℃条件下,钒的浸出率可达86%以上。由XRD,FTIR及钒的价态分析可知:空白焙烧能改变云母的内部结构,促进钒的转价;对于不同焙烧温度条件下的焙烧熟样,在浸出过程中加入含氟助浸剂,钒的浸出率较硫酸直接浸出时提高15%以上;热力学研究表明,含氟助浸剂中的F-易于与Si4+及Al3+反应生成络合离子,使白云母发生的反应的ΔGθ明显小于直接与酸的反应的ΔGθ;添加含氟助浸剂的酸浸体系对白云母结构的破坏能力明显大于空白焙烧过程。
The vanadium-containing stone coal from a certain place in Hubei Province was used as raw material to study the leaching process of vanadium by calcination-assisted leaching with acid leaching. The leaching time of 4 h, the liquid-solid ratio of 1.5:1.0, the calcination temperature, Calcination time, the concentration of sulfuric acid, the amount of soaking agent and the leaching temperature on vanadium leaching were investigated. The main reactions of the muscovite with acid during the leaching process were listed. The ΔGθT of each reaction at different temperatures was calculated and ΔGθ- T’s diagram. The results show that the leaching rate of vanadium can reach 86% when the roasting temperature is 700 ℃, the roasting time is 1 h, the concentration of sulfuric acid is 4 mol·L-1, the amount of fluorine-containing auxiliaries is 5% %the above. The XRD, FTIR and vanadium valence analysis show that: blank roasting can change the internal structure of mica and promote the conversion of vanadium; roasting cooked samples under different roasting temperature conditions, adding fluorine impregnant, vanadium The leaching rate is more than 15% higher than the direct leaching of sulfuric acid. Thermodynamic studies show that the F- in the fluorine-containing diagea is easy to react with Si4 + and Al3 + to form complex ions, which makes the ΔGθ of reaction of muscovite to be obviously smaller than that of direct reaction with acid . The acid-leaching system with fluorine-containing blends had a greater destructive effect on the muscovite structure than the blank calcination.