机械活化对石煤物化性质及提钒浸出的影响

Influence of Mechanical Activation on Mineral Properties and Process of Acid Leaching from Stone Coal

采用比表面积(BET)、扫描电镜(SEM)、X射线衍射分析(XRD)、红外分析(FTIR)、差示扫描量热(TG-DSC)等检测方法,对石煤矿样进行粒度、表面形态、矿物结构及热稳定性的分析,探索了活化前后含钒石煤物化性质的变化,并通过硫酸浸出工艺,研究了机械活化对含钒石煤钒浸出率的影响。研究结果表明,机械活化不仅能使矿样粒度变细,表面形态结构发生相应的变化,还能造成矿样内部化学键的破坏,晶格缺陷的产生等,主要表现为白云母层间吸附水的脱除及羟基结构的破坏,石英趋于非晶化;由于晶格缺陷的产生,使得部分机械能转化为内能储存在晶格中,矿样活性增强,热稳定性变差。受粒度、晶格结构及矿样活性等因素的影响,浸出剂与颗粒的接触面积增加,同时对目的矿物破坏的难度降低,浸出反应速率加快,从而达到强化提钒浸出的效果。在浸出剂浓度为15%(体积分数)的H2SO4,液固比1.5ml·g-1,5%(质量分数)助浸剂,搅拌强度200 r·min-1,浸出温度95℃,浸出时间6 h的条件下,随着活化时间的延长,钒浸出率逐渐增加,且浸出率变化与粒度的增加呈正相关;活化30 min时,浸出率达81.82%,与未活化时相比,提高了约10%。

The physical properties of particle size, surface morphology, mineral structure and thermal stability of stone coal were analyzed by means of such as specific surface area （BET）, detection methods such as scanning electron microscopy （SEM）, X-ray diffraction （ XRD）, infrared spectroscopy （ FTIR）, thermo gravimetric analysis and differential scanning calorimetry （ TG-DSC ）, the changes of stone coal containing vanadium in physicochemical properties before and after activation were studied. Moreover, the effect of mechanical activation on leaching rate was studied by acid leaching process. The results demonstrated that, mechanical activation could not only result in changes of sample size and surface morphology, but also caused internal bond destruction and lattice defects, mainly including removal of adsorbed water, destruction of hydroxyl structure in muscovite and amorphization of quartz. Owing to lattice defects, mechanical energy could be converted into internal energy stored in the lattice, which contributed to reaction activity increase and thermal stability decrease. Influenced by factors of particle size, crystal structure and leaching activity, the contact area between leaching agent and particle increased. At the same time, the difficulty of damaging the objective mineral reduced and leaching reaction sped up as well so as to strengthen the process of vanadium leaching from stone coal. When the concentration of the leaching agent was 15% （ volume fraction） H2SO4, ratio of liquid to solid was 1.5 ml.g-1, dosage of leach ant was 5% （ mass fraction）, stirring intensity was 200 r.min-~ and leaching temperature was 95 ~C, leaching thus was 6 h, the vanadium leaching rate increased gradually with acti- vation time prolonging. The leaching rate could reach 81.82% when activation time was 30 min, comparing with non-activated, the leaching rate increased about 10%.