Abstract:

Under the background of emission peak and carbon neutrality, CO₂ mineralization has attracted more attention as an effective carbon sequestration technology. For six kinds of industrial calcium-containing solid wastes, ammonium chloride solution was used to leach and prepare mineralization mother liquor, and then the direct and indirect mineralization experiments of CO₂ in simulated coal-fired flue gas were carried out at room temperature and pressure. The mineralization efficiency and mineralization products of six kinds of solid wastes were analyzed in detail, and the circulation ability of leaching agent to leach calcium-containing solid wastes was tested. The results showed that the leaching rate of Ca²⁺ in the six solid wastes was between 18.88% and 95.15% due to the different types and contents of calcium-containing mineral phases. The concentration of Ca²⁺ in the leaching solution was purified ash > sintering red mud > coal fired fly ash 2 > coal fired fly ash 1 > drying ash > Bayer red mud. After cyclic leaching of purified ash, coal fired fly ash 2 and sintering red mud by ammonium chloride solution, the indirect mineralization efficiency of coal fired fly ash 2 and purified ash only decreased by 1.44% and 1.34% with the increase of the number of cycles, while the indirect mineralization efficiency of sintering red mud decreased by 6.21%. Among the six kinds of solid waste, the calcium carbide purification ash had the highest indirect mineralization efficiency of 57.60%, and the sintering red mud had the highest direct wet mineralization efficiency of nearly 67.25%. The product of CO₂ indirect mineralization was rhombohedral calcite with a particle size of 2—5μm.

Key words: leaching, mineralization, carbon dioxide, industrial solid wastes, coal-fired flue gas

摘要：

双碳背景下，CO₂矿化作为一种有效固碳技术受到更多关注。本文针对6种工业含钙固废，分别采用氯化铵溶液浸出并制备矿化母液，然后在常温常压下开展直接和间接矿化模拟燃煤烟气中CO₂的实验，并对6种固废的矿化效率和矿化产物进行详细分析，同时测试了浸出剂浸出含钙固废的循环能力。结果表明，由于含钙矿物相种类与含量的不同，6种固废的Ca²⁺浸出率介于18.88%~95.15%之间，浸出液Ca²⁺浓度大小为：净化灰>烧结法赤泥>燃煤飞灰2>燃煤飞灰1>烘干灰>拜耳法赤泥。氯化铵溶液循环浸出净化灰、燃煤飞灰2和烧结法赤泥后，随着循环次数的增加，燃煤飞灰2和净化灰中的间接矿化效率仅降低了1.44%和1.34%，烧结法赤泥的间接矿化效率降低了6.21%。6种固废中电石净化灰拥有最高间接矿化效率达57.60%，烧结法赤泥拥有最高直接湿法矿化效率为67.25%。CO₂间接矿化的产物为粒径介于2~5μm的菱面体方解石。

关键词: 浸出, 矿化, 二氧化碳, 工业固废, 燃煤烟气