Abstract:

Tin (Sn) is an element with negative environmental effects. In recently years, samples collected from sediment from many places showed very rapid increasing ratio which suggests that Sn emitted from coal might be an important source. In this study, we try to make an overview on the progress of studying of Sn in Chinese coals. Generally, Sn in Chinese coals was 23 μg/g, relatively higher than the world average and the earth crust abundance. As the content of Sn in Chinese coal ranges from 0.4 to 10.5 μg/g, it is suitable to use the ICPMS or high sensitivity AAS as the measuring instruments after digestion with microwave oven. With the low content, Sn in coals hardly exists in the term of independent minerals. However, several kinds of possible modes of occurrence of Sn were proposed here, including cassiterite, sulfide tin compounds, Snincluded niobiumtantalum minerals, organically bonded Sn, Snincluded silicates and loosely bonded ionic Sn. Based on the occurrences of Sn, the genetic factor of some coal seams which were enriched in Sn was discussed here. Moreover, the mobile ionic Sn and organically bounded Sn should be paid much attention because of their high possibility of emitting into the environment.

Key words: tin, Sn, abundance, coal, modes of occurrence, trace element