Study on the distribution and gradation of arsenic in Chinese coals

Arsenic is one of the detrimental trace elements in coal.It is harmful to environment and human health.On the basis of data of arsenic content in coals has published in China until now,A statistic analysis of arsenic in coal of different ages,in different degree of metamorphism and at different provinces has been done.The results show that the frequency histogram for data and frequency density curve of data is unimodal and nearly symmetric.It indicates that the distribution of arsenic in coal fitting the normal distribution.Combining with the previous standard of arsenic content in coal,A new gradation for arsenic is put forward.Finally,A series prevention against arsenic pollution by coal usage and the threshold of arsenic in coal use are proposed.