Arsenic in Coal: Modes of Occurrence and Reduction via Coal Preparation - a Case Study

As one of the hazardous trace elements present in coal, removal of arsenic has been overlooked from the point of coal preparation. In this paper, we found that arsenic in coal is associated with pyrite. The various modes of arsenic occurrence via the sequential chemical extraction procedure were sulfide associated form > silicate associated form> carbonate associated form > organically bounded form> ion-exchangeable form. The float-sink test results showed that most of the arsenic was distributed in the high-density fraction, and the reduction of arsenic can be as high as 35.82%. Due to the existence of organic arsenic in coal, the <1.4 g/cm(3) fraction is higher in arsenic than 1.4 similar to 1.5g/cm(3) fraction. The reduction of arsenic by flotation remained above 50%. Research on organic arsenic in coal is the cruxes to break through for the reduction limit of toxic elements by preparation. The purpose of this article is to facilitate the understanding on the reduction of arsenic in coal by coal preparation and assist the further purification technology of arsenic in coal.