机械活化对高钙钒渣的物化性质及酸浸提钒的影响

Physical and Chemical Properties of High Calcium Vanadium Slag and Extraction of Vanadium by Acid Leaching with Mechanical Activation

研究机械活化对高钙钒渣的物化性质及酸浸提钒的影响。采用X射线衍射仪(XRD)、扫描电镜(SEM)、激光粒度分析仪(LPSA)、比表面积测试仪(BET)、红外分析(FTIR)等检测方法,分析不同活化时间高钙钒渣的物相结构、表观形貌、粒度和比表面积的变化规律。同时考察了不同活化时间高钙钒渣的钒浸出率,当活化30 min后,与未活化相比,钒的浸出率增加了约10%。研究结果表明,机械活化不仅能使高钙钒渣的粒度变小和比表面积增大,还使钒渣的物相结构发生一定的变化。主要表现为硫酸钙等物质衍射峰强度随活化时间的延长先增高后降低,间接表明了这些物质随着活化时间的延长先被释放出来而后又被包裹起来,从而影响了钒的浸出率。最后也研究了不同浸出时间高钙钒渣浸出率的变化,在H;SO;浓度200 g·L^(-1)、固液比1∶10 g·ml^(-1)、反应温度120℃、反应时间60 min、搅拌速度300 r·min^(-1)条件下,高钙钒渣的钒浸出率可达82.15%。

The high-calcium vanadium slag was the tailings after calcification roasting and acid leaching.The tailings contained 1%~3%vanadium,which had great utilization value.At present,Chinese and foreign scholars had done a lot of researches on the mechanical activation of minerals,the purpose of which were to change the occurrence state of minerals,increase their leaching activity,and improve the utilization rate of minerals.Therefore,this study used this as a basis to investigate the changes in phase,apparent morphology,particle size and specific surface area of the high-calcium vanadium slag after mechanical activation for different time.At the same time,the vanadium leaching rate of high calcium vanadium slag with different activation time was also investigated.The high-calcium vanadium slag used in the experiment was from Jiuyuan County,Sichuan Province.After crushing,ball milling,sieving and drying,the material with a particle size of less than 75μm was used as the experimental raw material.In each mechanical activation test,80 g high-calcium vanadium slag and 800 g steel balls were added to the ball milling jar.The particle size of the steel balls was 10 and 12 mm,and the ratio of the two particle size steel balls was 1∶1.And then the ball mill jars were symmetrically put into planetary ball mill.The ball mill speed for all batch experiments was 250 r·min^(-1).The activation time of the high-calcium vanadium slag was respectively 5,15,30,45,60 min.After the high-calcium vanadium slag was mechanically activated,50 g of the activated sample and 500ml of 200 g·L^(-1)H_(2)SO_(4)were added to the zirconium reactor,and then the mixed slurry was reacted at 120℃for 30 min.After the leaching residue was analyzed,it could be calculated that the vanadium leaching rate of the activated sample was 82.15%.Compared with the vanadium leaching rate of the unactivated sample,it was increased by about 10%.After the high-calcium vanadium slag was mechanically activated for different time,the results of X-ray diffraction(XRD)analysis showed that when the activation time was 30min,the CrVO_(3)in the high-calcium vanadium slag was completely released,while the CaSO_(4)·2H_(2)O,SiO_(2)and CaVH_(2)Si_(4)O_(12)in the high-calcium vanadium slag were released first and then encapsulated with the extension of activation time,Fe_(2)O_(3)and Fe_(2)TiO_(5)in the high-calcium vanadium slag were gradually released with the extension of the activation time.After the high-calcium vanadium slag was mechanically activated for different time,it could be seen from Fourier transform infrared spectroscopy(FTIR)analysis results that with the extension of mechanical activation time the position of the quartz absorption band in the range of 450~795 cm^(-1)remained unchanged,and the characteristic peak intensity did not change much.When the activation time was extended from 0 to 30 min,the absorption band of calcium sulfate at 1110 cm^(-1)narrowed,and the characteristic peak intensity gradually increased.When the activation time was extended from 30 to 60 min,the absorption band widened and the characteristic peak intensity weakened.The reason might be that calcium sulfate was first released and then encapsulated under the action of mechanical force.The characteristic peak of CaSO_(4)·2H_(2)O crystal water at 1620 and 1680 cm^(-1)increased with the activation time,the intensity of the absorption band increased first and then unchanged.The absorption peak intensity of the 30 min activated sample was the largest,the absorption peak intensity did not change much with the increase of activation time.It could be seen that the activation time was increased from 0 to 30 min,CaSO_(4)·2H_(2)O removed the most crystal water,the crystal water did not break away with the increase of activation time.The water molecule hydroxyl stretching vibration peak intensity of Ca SO_(4)·2H_(2)O at 3400 and 3528 cm^(-1)gradually strengthened with the increase of activation time.When the activation time was 60 min,there was little change.It could be seen that the change of the hydroxyl group of the water molecule of CaSO_(4)·2H_(2)Owas consistent with the change of the crystal water.From scanning electron microscopy(SEM)analysis of the samples at different activation time,it could be seen that the particles in the samples were larger before activation.After 5 and 15 min of activation,the particles in the sample began to disperse,but there were still large particles combined.After 30 min of activation,the particles in the samples were smaller and the dispersibility was better,and no large particles were seen.After 45 and 60 min of activation,the particles in the samples reappeared in a large block structure due to agglomeration.From the analysis of the particle size and specific surface area of samples with different activation time,it could be seen that mechanical activation significantly reduced the particle size of the high-calcium vanadium slag and increased the specific surface area.This was conducive to the contact of vanadium and acid during the leaching reaction,so that the leaching rate of vanadium had been significantly improved.Finally,the high-calcium vanadium slag was mechanically activated for 30 min,and then the activated sample reacted with acid for 60 min.The results of XRD analysis showed that the main phases of the leaching residue were Fe_(2)TiO_(5),CaSO_(4)and SiO_(2).The characteristic peaks of Fe_(2)O_(3),CrVO_(3)and CaVH^(2)Si_(4)O_(12)disappeared.It could be known that Fe_(2)O_(3),CrVO_(3)and CaVH^(2)Si_(4)O_(12)reacted with acid and entered the leaching solution.In addition,after activation and acid leaching,the crystal water of the CaSO_(4)·2H_(2)Owas removed,and CaSO_(4)entered the acid leaching slag.