Abstract:

Carbonation reaction of alkali-based industrial solid waste is one of the carbon sequestration strategies for mineralization to absorb CO₂ and reduce greenhouse gas emissions. In this study, the wet carbonation process was introduced for the first time, and through experimental tests using XRD, FTIR and TG-DTG, it was focused on exploring the effects of temperature change, stirring speed, carbonation time and liquid-solid ratio on the carbonation reaction of modified magnesium slag, and then discussed the carbonation products and carbon sequestration efficiency of modified magnesium slag under the four factors. The results showed that the mineral composition of modified magnesium slag was mainly dominated by β-C₂S, which was an industrial solid waste with good CO₂ storage capacity, and the carbonation products were mainly dominated by calcite-type calcium carbonate crystals and silica gel. After the carbonation reaction, the particle size of the modified magnesium slag carbonation product increased significantly, the specific surface area decreased, the particle size distribution became more uniform and the particle size distribution range became narrower. When the carbonation reaction temperature was 60℃, the aeration time was 30min, the liquid-solid ratio was 10mL/g and the stirring speed was 600r/min, the carbon sequestration efficiency of modified magnesium slag reached the maximum (28.4%), i.e. 1kg of modified magnesium slag could be mineralized to absorb 0.284kg of CO₂. Therefore, the wet carbonation process had a great application for the recycling of modified magnesium slag and the carbon dioxide sequestration potential.

Key words: CO₂ capture, multiphase reaction, waste treatment, wet carbonation, sequestration efficiency

摘要：

碱基工业固废的碳酸化反应是一种矿化吸收CO₂并减少温室气体排放的固碳策略之一。本研究首次引入湿法碳酸化工艺，通过借助X射线衍射、红外光谱测试、热重分析等实验测试，重点探究了温度变化、搅拌速度、碳酸化时间和液固比例对改性镁渣碳酸化反应的影响，进而讨论了4种因素下改性镁渣的碳酸化产物与固碳效率。结果表明，改性镁渣的矿物成分主要以β-C₂S为主，是一种具有良好储存CO₂能力的工业固废，碳酸化产物主要以方解石型碳酸钙晶体和二氧化硅凝胶为主。碳酸化反应后，改性镁渣碳酸化产物的粒径显著增大，比表面积减小，粒径分布变均匀，粒径分布范围变窄。当碳酸化反应温度为60℃、通气时间为30min、液固比为10mL/g、搅拌速度为600r/min时，改性镁渣的固碳效率达到最大（28.4%），即1kg改性镁渣可以矿化吸收0.284kg CO₂。因此，湿法碳酸化工艺对改性镁渣的回收利用及CO₂捕集均具有很大的应用潜力。

关键词: 二氧化碳捕集, 多相反应, 废物处理, 湿法碳酸化, 固碳效率