王超宇, 戚庭野, 冯国瑞, 杨颂, 王昊晨, 王林飞, 高歆于. 煅烧温度对柳叶灰火山灰活性的调控机制[J]. 工程科学学报, 2023, 45(12): 2005-2014. DOI: 10.13374/j.issn2095-9389.2022.10.14.003
引用本文: 王超宇, 戚庭野, 冯国瑞, 杨颂, 王昊晨, 王林飞, 高歆于. 煅烧温度对柳叶灰火山灰活性的调控机制[J]. 工程科学学报, 2023, 45(12): 2005-2014. DOI: 10.13374/j.issn2095-9389.2022.10.14.003
WANG Chaoyu, QI Tingye, FENG Guorui, YANG Song, WANG Haochen, WANG Linfei, GAO Xinyu. Study of the regulation mechanism of calcination temperature on the pozzolanic activity of willow leaf ash[J]. Chinese Journal of Engineering, 2023, 45(12): 2005-2014. DOI: 10.13374/j.issn2095-9389.2022.10.14.003
Citation: WANG Chaoyu, QI Tingye, FENG Guorui, YANG Song, WANG Haochen, WANG Linfei, GAO Xinyu. Study of the regulation mechanism of calcination temperature on the pozzolanic activity of willow leaf ash[J]. Chinese Journal of Engineering, 2023, 45(12): 2005-2014. DOI: 10.13374/j.issn2095-9389.2022.10.14.003

煅烧温度对柳叶灰火山灰活性的调控机制

Study of the regulation mechanism of calcination temperature on the pozzolanic activity of willow leaf ash

  • 摘要: 生物质能源作为可再生的清洁能源是传统化石能源的替代品之一,但是其作为工业燃料燃烧时会产生大量具有火山灰活性的生物质灰,研究煅烧温度对生物质灰火山灰活性的调控机制有助于生物质灰的高效利用. 基于此,本文测试评价了500、700、850 ℃柳叶灰的火山灰活性,采用X射线荧光光谱仪(XRF)、X射线衍射(XRD)、傅里叶红外光谱仪(FTIR)和激光粒度分析仪、显微电泳仪等表征手段,测试了柳叶灰的理化性质;考察柳叶灰替代20%质量分数水泥后柳叶灰–水泥基材料的力学性能;通过强度指数、活性离子析出能力和火山灰反应效率,评价柳叶灰的火山灰活性特征,结合扫描电镜(SEM)、XRD等表征手段,阐明煅烧温度对柳叶灰结构组成及火山灰活性调控机制. 结果表明:柳叶灰的主要氧化物为SiO2和CaO,柳叶灰替代部分水泥后500 ℃柳叶灰–水泥基材料抗压强度最大,强度指数为0.79,具有最强的火山灰活性;500 ℃和700 ℃柳叶灰Zeta电位的绝对值和电导率变化率大于850 ℃的,Si4+析出浓度随煅烧温度升高而下降,过高的煅烧温度会导致柳叶灰出现结渣现象影响火山灰反应的进行. 本研究为生物质灰火山灰活性的调控及在水泥基材料中的应用提供理论支撑.

     

    Abstract: As a renewable and clean source, biomass energy is one of the substitutes for traditional fossil energy. However, when biomass is burned as an industrial fuel, it produces a large amount of biomass ash with considerable pozzolanic activity. Currently, the activity of biomass ash is ignored in the utilization of biomass energy. Therefore, research on the regulation mechanism of calcination temperature on the pozzolanic activity of biomass ash will facilitate its efficient utilization. Therefore, we reviewed previous research and selected 500, 700, and 850 ℃ temperatures to calcinate willow leaves. The contents of SiO2, CaO, and other oxides in the willow leaf ash were determined through X-ray fluorescence spectrometer(XRF). The specific surface area of willow leaf ash was determined using a laser particle size analyzer. The mineral composition of willow leaf ash was characterized by X-ray diffraction (XRD), and the characterization of the chemical bonds of the minerals was supplemented by Fourier-transform infrared (FTIR) spectroscopy. The zeta potential of the willow leaf ash–Ca(OH)2 solution was determined through microelectrophoresis to evaluate the system’s stability. After determining the basic physical and chemical properties of willow leaf ash, the mechanical properties of willow leaf ash–cement-based materials were investigated by replacing 20% (mass fraction) cement with the ash, and the factors affecting performance were analyzed. The pozzolanic activity of willow leaf ash at 500, 700, and 850 ℃ was evaluated through the activity index. Rapid evaluation of pozzolanic activity was conducted by active ion extraction capability and inductively coupled plasma-optical emission spectrometer (ICP-OES) analyses. Scanning electron microscopy and XRD characterization methods were combined to analyze the effect of calcination temperature on the structure and composition of the ash and to elucidate the mechanism of the effect of calcination temperature on its pozzolanic activity. The results show that the SiO2 content in the ash was 20% to 30%, and the specific surface area increased with increasing temperature. However, the presence of xonotlite in willow leaf ash was detected through XRD at 850 ℃ Furthermore, the observed FTIR absorption peak at 1120.74 cm−1 corresponded to the stretching vibration of the Si–O–Si structure, which indicated that some amorphous SiO2 was crystallized. The absolute value of the zeta potential of the solution containing willow leaf ash at 500 ℃ and 700℃ was considerably higher than that at 850℃. After replacing a part of the cement with willow leaf ash, the willow leaf ash–cement-based material exhibited the highest compressive strength at 500 ℃ with an activity index of 0.79. The rate of conductivity variation of the willow leaf ash–Ca(OH)2 solution at 500 ℃ and 700 ℃ was higher than that at 850 ℃. The concentration of Si4+ precipitation decreased with the increase in calcination temperature, indicating that willow leaf ash had the highest pozzolanic activity at 500 ℃ followed by 700 ℃. Excessively high calcination temperatures lead to the crystallization of amorphous SiO2 and slagging in willow leaf ash, along with a decrease in the pozzolanic activity. This study provides theoretical support for the regulation of the pozzolanic activity of biomass ash and its applications.

     

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