Mapping of Trace Elements in Coal and Ash Research Based on a Bibliometric Analysis Method Spanning 1971-2017

Coal is the most important fossil energy used in China. The environmental impact of trace elements released in coal combustion has become one of the hottest issues in recent years. Based on a software named CiteSpace, and social network analysis (SNA), a bibliometric analysis of research into trace elements in coal and ash field during 1971-2017 is presented with the information of authors, countries, institutions, journals, hot issues and research trends in the present study. The study results indicate that: (1) Shifeng Dai, Robert B Finkelman, Guijian Liu and James C Hower have a large number of publications with great influence. (2) China (29.8%) and USA (22.2%) have high productivity in total publications. China and the USA correlate closely in the cooperative web system. (3) China University of Mining and Technology and Chinese Academy of Sciences take the leading position in the quantity of publications among all research institutions. (4) Energy and fuels, engineering and environmental science are three disciplines with the most studies in this field. (5) International Journal of Coal Geology, Fuel, Energy and Fuels and Fuel Processing Technology are the top four journals with the most publications in this field. (6) The enrichment origin and modes of occurrence of trace elements are the mainstream research related to trace elements in coal and ash. The environmental problems caused by coal combustion have promoted the development of trace elements in coal research, and human health is getting more and more popular in recent years. The study findings provide a better understanding of features of trace elements in coal and ash research, which could be taken as a reference for future studies in this field.