摘要
经热活化后的浮选尾煤是制备胶凝材料的理想原料,但热活化引起的碳排放极大地限制了其绿色资源化利用。在提高火山灰活性的同时有效减少因热活化产生的碳排放是尾煤大规模工业化利用的前提。利用纯CO_(2)气氛代替烟气中的CO_(2),初步探索了尾煤在烟气中活化同时对CO_(2)捕集的可行性。通过对比空气及CO_(2)气氛煅烧后尾煤的物化性质,分析了活化协同固碳与传统尾煤煅烧的火山灰活性差异以及尾煤的固碳性能。利用XRD、N_(2)吸附及TG分析了2种气氛活化固碳后尾煤的物化结构及固碳性能,利用尾煤与水泥混合后结石体的抗压强度为指标对活化固碳后尾煤的火山灰活性进行了评价,以活化固碳后尾煤中增加的CaCO_(3)质量为指标评价尾煤的固碳性能。通过研究不同龄期结石体的物化结构,揭示了固碳对尾煤水泥水化过程影响的机理。结果表明:空气气氛煅烧尾煤的火山灰活性高于CO_(2)气氛煅烧尾煤。空气及CO_(2)气氛下尾煤最佳活化温度为700℃,火山灰活性贡献率分别为29.98%、15.51%,标准养护至28 d后空气及CO_(2)气氛煅烧后尾煤-水泥结石体的抗压强度较原尾煤-水泥结石体分别增长了29.1%及6.9%;同时,CO_(2)气氛下尾煤在700℃实现最佳固碳效果,固碳率为0.93%。CO_(2)气氛煅烧尾煤参与水泥水化反应,水化后期煅烧尾煤中的活性物质与矿化产物CaCO_(3)对熟料水化及胶凝体系中钙钒石(AFt)的产生起正向促进作用,水化后期结石体比表面积增加、孔隙填充,提高了孔隙密实程度,结石体后期抗压强度显著升高。
The thermal activated flotation tailings are an ideal raw materials for the preparation of cementitious materials,but the carbon emission caused by thermal activation greatly limits their green resource utilization.The prerequisite of large-scale industrialization of tailings are to effective reduction of carbon emissions due to the thermal activation while increasing pozzolanic activity is a prerequisite for large-scale industrialization of tailings.It used pure CO_(2) atmosphere instead of the component of CO_(2) in flue gas.The feasibility of the tailings activated in flue gas meantime the CO_(2) fixation was discussed.Through the comparison of tailings activated at Air atmosphere with that of CO_(2)atmosphere,the effect of activation and carbon fixation on the pozzolanic activity and capacity of carbon fixation of activated tailings was analyzed.XRD,N_(2) adsorption and TG were used to analyze the physicochemical structure and carbon fixation performance of the tailings after two kinds of atmospheres activation and carbon fixation.The pozzolanic activity of the activated carbon fixation tailings were evaluated using the compressive strength of the stone after mixing the tailing with cement as an index.By studying the physicochemical structure of stones at different curing ages,the mechanism of the influence of carbon fixation on the hydration process of tailings-cement were revealed.The results show that the pozzolanic activity of the coal calcined in Air atmosphere is higher than that of the coal calcined in CO_(2) atmosphere.The optimal activation temperature of tailings under Air and CO_(2) atmosphere is 700℃,and the contribution of pozzolanic activity is 29.98%and 15.51%,respectively.After standard curing for 28 days,the compressive strength of tailings-cement stone calcination under Air and CO_(2) atmosphere is 29.1%and 6.9%higher than that of raw coal-cement stone.At the same time,the tailings achieves the best carbon fixation effect at 700℃under CO_(2) atmosphere,and the carbon fixation rate is 0.93%.The tailings calcined in CO_(2) atmosphere participates in cement hydration reaction,and the active substances and mineralization product CaCO_(3) positively promote the hydration of clinker and production of ettringite(AFt).In the late hydration stage,the specific surface area of the hardened pastes increased and the pores filled,which improved the porosity density,and the compressive strength of the hardened pastes increased significantly.
作者
袁美娟
樊盼盼
鲍卫仁
常丽萍
冯国瑞
韩艳娜
廖俊杰
郭军
YUAN Meijuan;FAN Panpan;BAO Weiren;CHANG Liping;FENG Guorui;HAN Yanna;LIAO Junjie;GUO Jun(College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology,Taiyuan 030024,China;Key Laboratory of Coal Science and Technology,Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Energy Institute,Taiyuan 030024,China;Shanxi Coking Coal Group Co.,Ltd.,Taiyuan 030024,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第S01期314-324,共11页
Journal of China Coal Society
基金
山西省自然科学研究面上资助项目(202203021211137)
山西浙大新材料与化工研究院研发资助项目(2022SX-TD010)
中国博士后科学基金面上资助项目(2021M702049)
关键词
尾煤
火山灰
热活化
固碳
胶凝材料
物化结构
flotation tailings
pozzolanic
thermal activation
carbon fixation
cementitious material
physicochemical structure
作者简介
袁美娟(1995—),女,陕西咸阳人,硕士研究生。E-mail:yuanmeijuan0304@163.com;通讯作者:韩艳娜(1985—),女,内蒙古呼伦贝尔人,副教授,博士。E-mail:hanyanna0504@163.com
