Occurrence characteristics of mercury in high-mercury coal and distribution rule of mercury in products of an air dense medium fluidized bed

Abstract

Mercury emitted from direct combustion of high-mercury coal does great harm to the environment. To make good use of high-mercury coal, it is necessary to study the occurrence characteristics of mercury in coal and high-efficient methods of mercury removal. In this paper, high-mercury coal of Guizhou Province of China was taken as an object to study the nature of mercury in coal and the rule of mercury removal by dry preparation method. Mercury mainly distributes in the medium and high density fractions, and has a good affinity with silicon, aluminum, iron, titanium, potassium, calcium, zinc, sodium and magnesium. It exists in minerals formed by these elements and presents significant correlation with ash in coal. After the high-mercury coal is separated by air dense medium fluidized bed, mercury content of clean coal is reduced to 1/10 of raw coal, while mercury content of gangue is increased to 3 times that of raw coal. This indicates that mercury in raw coal is rejected greatly by ADMFB and enriched in high-density fractions. The rates of ash removal and mercury removal decrease with the density and present a very high correlation. Keywords: Occurrence of mercury, Affinity, Air dense medium fluidized bed, Correlation of mercury and ash removal, Distribution rule of mercury