• 关键词：粉煤灰  CO₂矿化  矿物变化  镁/铁碳酸盐

• 基金项目：国家重点研发计划（No.2021YFA1201704）

• 李家碧
• 南京大学环境学院，污染控制与资源化研究国家重点实验室，南京 210023

• 纪龙
• 南京大学环境学院，污染控制与资源化研究国家重点实验室，南京 210023

• 于海
• CSIRO能源，纽卡斯尔，新南威尔士2304，澳大利亚

• David French
• 新南威尔士大学，悉尼，新南威尔士2052，澳大利亚

• Mihaela Grigore
• CSIRO能源，北莱德，新南威尔士2113，澳大利亚

• 王晓龙
• 中国华能集团清洁能源技术研究院有限公司，北京 102209

• 花铭
• 南京大学环境学院，污染控制与资源化研究国家重点实验室，南京 210023

• 摘要：粉煤灰矿化CO₂是一种极具前景的减少燃煤电厂CO₂排放的技术.然而，目前还缺乏从矿物学角度对碳酸化反应机理的详细认识.本研究选取了3种粉煤灰开展碳酸化实验和矿物学研究，考察碳酸化过程中温度对碳酸化能力及粉煤灰矿物学变化的影响.结果表明，在任一温度下，BJ粉煤灰的碳酸化率均高于YA和LY粉煤灰，这是由于BJ粉煤灰中硬石膏、钙铁石和无定形相等活性矿物相含量较高，LY粉煤灰缺少 高活性的钙、镁结晶相.对YA粉煤灰而言，升高温度可显著提高透辉石、尖晶石、黑钙铁矿和方镁石的转化率.在碳酸化YA粉煤灰中同时检测出碳酸钙和碳酸镁/铁，说明除含钙相其他活性元素（Mg和Fe）也参与了碳酸化过程.因此，需要对每个粉煤灰原始材料的矿物学和操作温度进行具体的个案优化，以最大限度地提高固定CO₂能力和碳酸化率.结果还表明温度对不同晶型碳酸钙的形成具有重要作用.方解石在低温（40和80 ℃）下形成，而文石在高温（180和220 ℃）下形成.

• Abstract：CO₂ mineralization by fly ash is a promising option for mitigating CO₂ emissions from coal-fired power plants. However， there is still an absence of a detailed understanding of carbonation mechanisms from a mineralogical point of view. To deal with this problem， three fly ashes were selected in this study to investigate carbonation and mineralogical performance， especially the effect of temperature on carbonation capacity and the mineralogical change of fly ashes in carbonation reactions. The results show that the carbonation efficiency of BJ fly ash was higher than that of YA and LY fly ashes at any temperature， due to the presence of higher reactive mineral phases such as anhydrite， brownmillerite， and amorphous phase in BJ ash and the lack of highly active calcium and magnesium crystal phases in LY ash. For YA ash， the conversion of diopside， spinel， srebrodolskite， and periclase can be significantly enhanced by the elevated temperature. Not only Ca-carbonate but also Mg/Fe-carbonates were detected in carbonated YA ash samples， indicating that other active elements （Mg and Fe） besides the calcium-containing phase were also involved in the carbonation process. Thus， the mineralogy of the original material and the operating temperature need specific case-by-case optimization for each fly ash to maximize the CO₂ sequestration capacity and carbonation efficiency. The results also show that temperature played an important role in the formation of different crystal forms of calcium carbonate. The calcite was favored at low temperatures （40 and 80 ℃） while aragonite was formed at high temperatures （180 and 220 ℃）.

• Key words：fly ash  CO₂ mineralization  mineral change  Mg/Fe-carbonates

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