Liu Jie, Zhao Jihui, Wang Yiren, Zhao Yunqi, Wu Kunrun
School of Civil Engineering, Sun Yat-sen University & Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China.
School of Civil Engineering, Sun Yat-sen University & Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China.
Sci Total Environ. 2024 Oct 15;947:174498. doi: 10.1016/j.scitotenv.2024.174498. Epub 2024 Jul 5.
In this study, the occurrence and distribution of heavy metals in coal gasification fine ash (CGFA) with different particle sizes were investigated to ensure safer disposal and utilization strategies for CGFA. These measures are critical to sustainable industrial practices. This study investigates the distribution and leachability of heavy metals in CGFA, analyzing how these factors vary with particle size, carbon content, and mineral composition. The results demonstrated that larger CGFA particles (>1 mm) encapsulated up to 70 % more heavy metals than smaller particles (<0.1 mm). Cr and Zn were present in higher concentrations in larger CGFA particles, whereas volatile elements such as Zn, Hg, Se, and Pb were found in relatively higher contents in finer CGFA particles. At least 70 % of Hg in CGFA was present in an acid-soluble form of speciation, whereas Cd, Zn, and Pb were mostly present in a reducible form of speciation, which could be attributed to the presence of franklinite. More than 40 % of Cd and Zn in fine CGFA particles exist in an acid-soluble form. With the exception of CGFA_1.18, Se in CGFA mainly existed in an oxidizable form at a ratio of 60 %-80 %. This could be attributed to the presence of bassanite particles as well as the higher affinity of Se for S. In contrast, Cr, Cu, and As were mostly present in residual speciation forms owing to their parasitism in quartz, sillimanite, and amorphous Fe solid solution in CGFA. Additionally, the study revealed that there was no significant relationship between heavy metal content, leaching behavior, and carbon content in CGFA. Based on combined analyses using toxicity characteristic leaching procedure (TCLP) leaching concentrations and risk assessment code (RAC) results, it is recommended to focus on the environmental risks posed by Cd, Cr, Pb, Zn, and Hg in CGFA during their modification and utilization processes.
在本研究中，对不同粒径的煤气化细灰（CGFA）中重金属的赋存及分布情况进行了调查，以确保CGFA的处置和利用策略更为安全。这些措施对可持续工业实践至关重要。本研究调查了CGFA中重金属的分布及浸出性，分析了这些因素如何随粒径、碳含量和矿物组成而变化。结果表明，较大的CGFA颗粒（>1毫米）所含重金属比较小颗粒（<0.1毫米）多70%。Cr和Zn在较大的CGFA颗粒中浓度较高，而挥发性元素如Zn、Hg、Se和Pb在较细的CGFA颗粒中含量相对较高。CGFA中至少70%的Hg以酸溶态存在，而Cd、Zn和Pb大多以可还原态存在，这可能归因于锌铁尖晶石的存在。细CGFA颗粒中超过40%的Cd和Zn以酸溶态存在。除CGFA_1.18外，CGFA中的Se主要以氧化态存在，比例为60%-80%。这可能归因于硬石膏颗粒的存在以及Se对S的较高亲和力。相比之下，Cr、Cu和As大多以残渣态存在，因为它们寄生于CGFA中的石英、硅线石和非晶态铁固溶体中。此外，研究表明，CGFA中的重金属含量、浸出行为和碳含量之间没有显著关系。基于毒性特性浸出程序（TCLP）浸出浓度和风险评估代码（RAC）结果的综合分析，建议在CGFA的改性和利用过程中关注Cd、Cr、Pb、Zn和Hg所带来的环境风险。
