Carbonation Corrosion Resistance of Circulating Fluidized Bed Ash-Slag

doi:10.16552/j.cnki.issn1001-1625.2025.0220

Abstract

Abstract: Circulating fluidized bed (CFB) boiler fly ash and bottom slag contains a large number of sulfur-containing minerals, which hydrates to form ettringite when used in cement concrete, resulting in poor stability, thus restricting its large-scale application in cement concrete. In this paper, three kinds of CFB fly ash and CFB bottom slag were taken as research objects, CFB ash-slag test blocks were prepared by atmospheric pressure and medium temperature moisture retention methods, and the influence of carbonation corrosion on the compressive strength of CFB ash-slag test blocks was studied. The mechanism of carbonation corrosion resistance of CFB ash-slag test blocks was analyzed by XRD, TG-DTG and SEM tests. The results indicate that the compressive strength of CFB ash-slag test blocks decreases significantly after carbonation corrosion. XRD and TG-DTG test indicate that carbonation corrosion leads to the decomposition of hydration products ettringite in CFB ash-slag test blocks, producing calcium carbonate and calcium sulfate. SEM microstructure analysis shows that carbonation corrosion decomposes needle-rod ettringite in the cracks of test blocks, generating calcium carbonate. The ettringite originally filled in the crack gaps of CFB ash-slag test blocks is carbonized and decomposed, and the gaps are not filled with ettringite, resulting in a significant reduction in the compressive strength of test blocks. The related research reveals the carbonation corrosion resistance and mechanism of CFB ash-slag, and provides a theoretical basis for its resource utilization.

Key words: circulating fluidized bed boiler fly ash and bottom slag, ettringite, calcium carbonate, carbonation corrosion, microanalysis

CLC Number:

TU522

XIE Laikun, QIN Xiaohan, GUO Wenbin, ZHOU Mingkai. Carbonation Corrosion Resistance of Circulating Fluidized Bed Ash-Slag[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(7): 2528-2537.

References

[1] 李卫红, 郭文斌, 郭向兵, 等. CFB灰渣混凝土的组成设计与应用研究[J]. 硅酸盐通报, 2024, 43(7): 2530-2538.
LI W H, GUO W B, GUO X B, et al. Composition design and application of CFB ash-slag concrete[J]. Bulletin of the Chinese Ceramic Society, 2024, 43(7): 2530-2538 (in Chinese).
[2] 王智. 流化床燃煤固硫渣特性及其建材资源化研究[D]. 重庆: 重庆大学, 2002.
WANG Z. Study on characteristics of sulfur-fixing slag from fluidized bed coal combustion and its resource utilization as building materials[D]. Chongqing: Chongqing University, 2002 (in Chinese).
[3] 何科文, 卢忠远, 李军, 等. 循环流化床固硫灰渣性能比较研究[J]. 武汉理工大学学报, 2014, 36(3): 6-13.
HE K W, LU Z Y, LI J, et al. Comparative study on properties of circulating fluidized bed combustion ash and slag[J]. Journal of Wuhan University of Technology, 2014, 36(3): 6-13 (in Chinese).
[4] 黄叶, 钱觉时, 王智, 等. 循环流化床锅炉固硫灰与煤粉锅炉粉煤灰的比较研究[J]. 粉煤灰综合利用, 2009, 23(3): 7-9+13.
HUANG Y, QIAN J S, WANG Z, et al. Comparative study of CFB ashes and PC ashes[J]. Fly Ash Comprehensive Utilization, 2009, 23(3): 7-9+13 (in Chinese).
[5] 郑洪伟. 流化床燃煤固硫灰渣中无水石膏作用研究[D]. 重庆: 重庆大学, 2008.
ZHENG H W. Study on the function of anhydrous gypsum in fluidized bed coal-fired sulfur-fixing ash[D]. Chongqing: Chongqing University, 2008 (in Chinese).
[6] ZHOU M K, CHEN P, CHEN X, et al. Study on hydration characteristics of circulating fluidized bed combustion fly ash (CFBCA)[J]. Construction and Building Materials, 2020, 251: 118993.
[7] 钱觉时, 郑洪伟, 宋远明, 等. 流化床燃煤固硫灰渣的特性[J]. 硅酸盐学报, 2008, 36(10): 1396-1400.
QIAN J S, ZHENG H W, SONG Y M, et al. Special properties of fly ash and slag of fluidized bed coal combustion[J]. Journal of the Chinese Ceramic Society, 2008, 36(10): 1396-1400 (in Chinese).
[8] 宋远明, 钱觉时, 刘景相, 等. SO₃对固硫灰渣胶凝系统水化及性能的影响[J]. 建筑材料学报, 2013, 16(4): 688-693.
SONG Y M, QIAN J S, LIU J X, et al. Effect of SO₃ on the hydration and performance of CFBC ash cementitious system[J]. Journal of Building Materials, 2013, 16(4): 688-693 (in Chinese).
[9] 宋远明. 流化床燃煤固硫灰渣水化研究[D]. 重庆: 重庆大学, 2007.
SONG Y M. Study on hydration of sulfur-fixing ash from fluidized bed coal combustion[D]. Chongqing: Chongqing University, 2007 (in Chinese).
[10] 宋远明, 钱觉时, 王智, 等. 固硫灰渣对水泥胶砂耐久性影响研究[J]. 建筑材料学报, 2010, 13(1): 66-69.
SONG Y M, QIAN J S, WANG Z, et al. Effect of fluidized bed combustion(FBC) ashes on durability of cement mortar[J]. Journal of Building Materials, 2010, 13(1): 66-69 (in Chinese).
[11] 宋远明, 钱觉时, 王智. 燃煤灰渣火山灰反应活性[J]. 硅酸盐学报, 2006, 34(8): 962-965.
SONG Y M, QIAN J S, WANG Z. Pozzolanic reactivity of coal ashes[J]. Journal of the Chinese Ceramic Society, 2006, 34(8): 962-965 (in Chinese).
[12] LI D L, SUN R, WANG D M, et al. Study on the pozzolanic activity of ultrafine circulating fluidized-bed fly ash prepared by jet mill[J]. Fuel, 2021, 291: 120220.
[13] 裴晓波. CFB脱硫灰渣高性能混凝土性能及应用研究[D]. 太原: 中北大学, 2019.
PEI X B. Study on performance and application of CFB desulfurization ash high performance concrete[D]. Taiyuan: North University of China, 2019 (in Chinese).
[14] 李军, 董静. 脱硫灰渣基混凝土的耐久性研究[J]. 混凝土, 2019(4): 66-70.
LI J, DONG J. Durability of desulphurized ash based concrete[J]. Concrete, 2019(4): 66-70 (in Chinese).
[15] 燕伟, 李驰, 邢渊浩, 等. 循环流化床多元固废粉煤灰基水泥胶砂固碳试验研究[J]. 材料导报, 2025, 39(9): 103-109.
YAN W, LI C, XING Y H, et al. Experimental study on carbon fixation of circulating fluidized bed multi-solid waste fly ash-based cement mortar[J]. Materials Reports, 2025, 39(9): 103-109 (in Chinese).
[16] 刘洋, 李驰, 高瑜, 等. 碳化条件下循环流化床粉煤灰的水化性能[J]. 建筑材料学报, 2024, 27(9): 837-845.
LIU Y, LI C, GAO Y, et al. Hydration properties of circulating fluidized bed fly ash under carbonation condition[J]. Journal of Building Materials, 2024, 27(9): 837-845 (in Chinese).
[17] 上官芊. CFB锅炉灰渣应用过程中的膨胀机理与碳化抑制措施研究[D]. 上海: 华东理工大学, 2024.
SHANGGUAN Q. Study on expansion mechanism and carbonization inhibition measures of CFB boiler ash during application[D]. Shanghai: East China University of Science and Technology, 2024 (in Chinese).
[18] 宋中旭, 王洋, 陈衡, 等. 活性炭及其碱改性对超硫酸盐水泥抗碳化性能的影响[J]. 硅酸盐学报, 2025, 53(2): 406-415.
SONG Z X, WANG Y, CHEN H, et al. Influence of activated carbon and its alkaline treatment on carbonation resistance of supersulfated cement[J]. Journal of the Chinese Ceramic Society, 2025, 53(2): 406-415 (in Chinese).
[19] WU Q Y, XUE Q Z, YU Z Q. Research status of super sulfate cement[J]. Journal of Cleaner Production, 2021, 294: 126228.
[20] STEINER S, LOTHENBACH B, PROSKE T, et al. Effect of relative humidity on the carbonation rate of portlandite, calcium silicate hydrates and ettringite[J]. Cement and Concrete Research, 2020, 135: 106116.
[21] MASOUDI R, HOOTON R D. Examining the hydration mechanism of supersulfated cements made with high and low-alumina slags[J]. Cement and Concrete Composites, 2019, 103: 193-203.
[22] 颜哩哩, 周文, 尤迁, 等. 基于DSC-TG的钙矾石半定量分析方法[J]. 新型建筑材料, 2015, 42(2): 41-43.
YAN L L, ZHOU W, YOU Q, et al. Semi quantifying ettringite by DSC-TG method[J]. New Building Materials, 2015, 42(2): 41-43 (in Chinese).
[23] 邹瑞珍, 孙淑巧, 陈贤拓. 钙矾石热稳定性与碳化率关系研究[J]. 河北轻化工学院学报, 1995, 16(4): 64-67.
ZOU R Z, SUN S Q, CHEN X T. Study on the relation between thermal stability and carbonation rate of ettringite[J]. Journal of Hebei University of Science and Technology, 1995, 16(4): 64-67 (in Chinese).
[24] 苏少龙, 曲晓龙, 钟读乐, 等. 工业氢氧化钙中氧化钙、氢氧化钙及碳酸钙测定方法的研究[J]. 无机盐工业, 2020, 52(5): 75-77.
SU S L, QU X L, ZHONG D L, et al. Study on determination of CaO, Ca(OH)₂ and CaCO₃ in industrial calcium hydroxide[J]. Inorganic Chemicals Industry, 2020, 52(5): 75-77 (in Chinese).
[25] 周健, 李伟华, 皮振宇, 等. 硫铝酸盐水泥基材料抗碳化性能研究进展[J]. 硅酸盐通报, 2024, 43(8): 2711-2725.
ZHOU J, LI W H, PI Z Y, et al. Research progress on carbonation resistance of calcium sulfoaluminate cement-based materials[J]. Bulletin of the Chinese Ceramic Society, 2024, 43(8): 2711-2725 (in Chinese).
[26] NDIAYE K, CYR M, GINESTET S. Durability and stability of an ettringite-based material for thermal energy storage at low temperature[J]. Cement and Concrete Research, 2017, 99: 106-115.
[27] PLANK J, ZHANG-PREßE M, IVLEVA N P, et al. Stability of single phase C₃A hydrates against pressurized CO₂[J]. Construction and Building Materials, 2016, 122: 426-434.
[28] LU B, HUO Z, XU Q Y, et al. Characteristics of CSH under carbonation and its effects on the hydration and microstructure of cement paste[J]. Construction and Building Materials, 2023, 364: 129952.