CO2等温室气体大量排放引起了全球气候变暖等生态问题,已成为全人类生存面对的重大挑战,CO2矿化是应对此挑战的关键技术之一。相对富煤、贫油、少气的能源资源禀赋格局导致中国主体能源仍以CO2排放强度高的煤炭为主,其燃烧产生的工业固废粉煤灰也面临巨大的处理难题。相比传统矿化原料,粉煤灰因具有产量大、获取容易和运输成本低等特点受到广泛关注。粉煤灰自身可通过直接矿化和间接矿化实现CO2矿化封存,在CO2矿化封存的同时,可大幅降低与粉煤灰堆积或处理相关的环境风险。在碳达峰和碳中和目标下,利用粉煤灰矿化封存CO2是一项应对全球变暖具有巨大潜力的高效策略。介绍了我国粉煤灰排放和利用现状,回顾了粉煤灰直接矿化和间接矿化的研究进展,对比分析了不同矿化工艺的优缺点,明晰了CO2矿化过程中工艺参数对粉煤灰矿化效率的调控机理。针对粉煤灰矿化CO2缺乏机制性的解释这一问题,通过介绍常用于描述CO2矿化反应的缩核模型和表面覆盖模型,厘清矿化过程中气液扩散等控制矿化速率的机制。最后分析了粉煤灰矿化过程中现存的问题和未来研究方向,旨在为利用粉煤灰固废矿化CO2提供借鉴。

CO2 mineralization is one of the key technologies to meet the challenge of global warming and other ecological problems causedby the massive emission of greenhouse gases such as CO2, which has become a major challenge to the survival of all mankind. The energyresource endowment pattern of " relatively coal-rich, oil-poor and gas-poor" has led to the fact that China′s main energy source is stilldominated by coal, which has a high CO2 emission intensity, and the industrial solid waste generated from the combustion of coal fly ashalso faces a huge problem of disposal. Compared with traditional mineralized raw materials, coal fly ash has received widespread attentiondue to its abundant reserves, easy accessibility and low transportation costs. Coal fly ash can achieve CO2 mineralization and sequestrationthrough direct and indirect mineralization, and reduce the environmental risks associated with the accumulation or disposal of coal fly ashwhile CO2 mineralization and sequestration is taking place. Under the goal of carbon peaking and carbon neutrality, the use of coal fly ashto mineralize and sequester CO2 is an efficient strategy with great potential to combat global warming. The current status of coal fly ashemissions and utilization in China were described. The research progress of direct and indirect coal fly ash mineralization was reviewed, theadvantages and disadvantages of different mineralization processes were compared and analyzed, the regulation mechanism of the processparameters on the efficiency of coal fly ash mineralization in the process of CO2 mineralization was clarified. In order to address the lackof mechanistic explanation of CO2 mineralization from coal fly ash, the mechanisms of gas-liquid diffusion and other mechanisms controlling the mineralization rate during the mineralization process were clarified through the introduction of the shrinking nucleus model and thesurface coverage model, which were commonly used to describe the CO2 mineralization reaction. Finally, the existing problems and futureresearch directions of the coal fly ash mineralization process were analyzed, aiming to provide a reference for the use of coal fly ash solidwaste to mineralize CO2.

0 引言

1 我国粉煤灰排放及利用现状

2 直接矿化法

   2.1 直接气固矿化（干法）

   2.2 直接气液矿化（湿法）

3 间接矿化法

   3.1 无机酸萃取

   3.2 铵盐萃取

   3.3 有机酸萃取

4 矿化机理

   4.1 缩核模型

   4.2 表面覆盖模型

5 结语