摘要
以宁武煤田两个洗煤厂原煤及洗选产物为研究对象,采用微波消解与氢化物发生-原子荧光光谱相结合方法考察了洗煤过程硫和砷迁移规律,采用砷质量平衡验证的逐级化学提取法探讨了原煤、精煤、矸石、洗中煤和煤泥燃烧后硫和砷形态转化与释放特性及其依赖性。原煤中20%−28%硫和砷迁移至精煤中,46%−61%迁移至矸石中,Pearson相关系数结果表明,样品中无机矿物质是硫和砷迁移的控制因素。精煤中有机硫和砷提高至30%−50%,而矸石中无机硫和砷占比达90%以上,说明原煤及洗选产物中砷与硫赋存形态具有一定相关性。精煤中较多的有机硫和砷在500℃以下伴随水分和挥发分析出呈现明显释放特征,矸石中以无机态为主的砷则主要在500−1000℃伴随黄铁矿和硫酸盐等矿物质分解与硫一起释放,体现了原煤及洗选产物燃烧时硫与砷释放的同步性。精煤中硫和砷释放速率最快,300和200 s分别达到最大释放率80%−95%和60%−75%;矸石中最慢,300 s时砷达到最大释放率40%−45%,而硫600 s时仍未达最大释放率;洗中煤和原煤介于精煤和矸石之间,样品燃烧时硫和砷赋释放速率差异是由其固有赋存形态差异所致。
Two raw coals and their washery products were collected from two coal-washing plants of Ningwu coal field,Shanxi,China.The migration behaviors of sulfur(S)and arsenic(As)during coal washing process were investigated by the microwave digestion method together with hydride generation-atomic fluorescence spectrometry.Based on the checked mass balance of As,a sequential-chemical-extraction method was used to explore the dependence between speciation transformation and release characteristics of S and As during the combustion process of raw coal,cleaned coal,coal gangue,middling coal,or coal slime.The results show that 20%–28%of S and As in raw coal are migrated to the cleaned coal,and 46%–61%of them to gangue.Pearson correlation coefficient identifies that the inorganic minerals in samples control the migration behavior of S and As.Compared with the elements in raw coal,the proportions of organic S and As in cleaned coal increase to 30%–50%,while the inorganic S and As in coal gangue account for more than 90%,which indicates the dependence between the species of S and As in raw coal and its washery products.The relatively large amount of organic S and As in the cleaned coal obviously release together with water and volatile matters below 500℃.While the inorganic bonded As and S in gangue mainly release during the decomposition process of pyrite,sulfate and other inorganic minerals between 500 and 1000℃,which shows the consistency of S and As release characteristics during combustion of raw coal or washery product.The release rates of S and As from the cleaned coal are the fastest among all samples and the corresponding maximum release ratios are 80%–95%at 300 s and 60%–75%at 200 s,respectively,whilst their release rates from gangue are the slowest and As reaches the maximum release ratio of 40%–45%at 300 s but S doesn’t get to the maximum release ratio even at 600 s.The release rates of S and As from the middling coal or raw coal are between the cleaned coal and gangue.The different release rates of
作者
刘轩
赵元财
滕阳
张锴
LIU Xuan;ZHAO Yuan-cai;TENG Yang;ZHANG Kai(Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation,North China Electric Power University,Beijing 102206,China;Xi’an Thermal Power Research Institute Co.,Ltd.,Xi’an 710054,China)
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2022年第7期787-797,共11页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金与山西煤基低碳联合基金重点项目(U1910215)资助。
关键词
煤炭洗选
硫
砷
迁移行为
赋存形态
燃烧
释放特性
coal washing
sulfur
arsenic
migration behavior
speciation
combustion
release characteristics
