超声波强化钙基废渣碳酸化固定CO2的性能

Enhancement of carbon dioxide sequestration with calcium-based residues by ultrasonics

钙基废渣碳酸化固定CO2可实现CO2的永久封存,并可实现CO2原位固定,但苛刻的反应条件、过慢的反应速率是困扰该技术发展的瓶颈。对超声波作用下的钙离子浸出及其碳酸化反应特性进行了实验研究,并与搅拌浸出过程进行了对比,考察了浸出条件的影响及其碳酸化反应过程中溶液pH值与电导率变化特性,对碳酸化反应产物进行了XRD、SEM和TGA分析。结果表明,超声波可有效促进Ca2+从钙基废渣中浸出,其促进效果与废渣种类、浸出时间、超声波功率、浸取剂pH值、浆液存放量和废渣粒度等有关,钢渣和电石渣的含钙量、浸出率和超声波强化效果都较其他废渣高;钙离子浸出浓度随超声波功率的增强而增多;浸取剂pH值越低,浸出浓度越高;废渣粒度越高,超声波作用越明显。超声波对碳酸化反应也有强化效果,与机械搅拌相比,在超声波作用下固碳率更高,碳酸化反应程度更高。

Although carbonation sequestration with calcium-based residues can achieve in-situ fixation and permanent storage of CO2,the process barriers are harsh reaction condition and slow reaction rate.In this paper leaching characteristics of Ca2＋ from residues and its carbonation were tested in an ultrasonic-assisted reactor,and compared with those obtained under stirring condition.Effect of different process parameters for leaching,and change of pH and conductivity for carbonation reaction was measured and analyzed.The products from carbonation were characterized by XRD,SEM and TGA techniques.The results show that the leaching of Ca2＋ from calcium-based residues can be effectively promoted by ultrasonic-assisted,which increases with enlargement of ultrasonic power and depends on type of residue,leaching time,pH of leaching solution,slurry volume as well as particle size of residue.The Ca content,leaching efficiency and ultrasonic-assisted effect are higher for steel slag and carbide slag than for other residues.The Ca2＋ concentration in leaching liquor increases with enlargement of ultrasonic power and decrease of pH.The ultrasonic enhancement effect is more obvious for bigger residue particles.Compared with mechanical stirring,not only leaching process but also carbonation reaction can be strengthened by ultrasonic-assisted.