Research to Trace Element during Huadian Oil Shale Pyrolysis

Abstract

Oil shale is quite abundant in the world. Today, the industry of oil shale retorting for shale oil production sprang up because of the deficiency in oil. In order to study the migratory behavior of trace elements during oil shale pyrolysis, the experiment was performed at different temperatures from 360 to 560°C on retorter in lab with the oil shale of Hudian China. The trace elements of Ba, Co, Cr, Cu, Mn, Ni, P, Pb, Sr, Ti, V, Y in oil shale and spent shale (semi-coke) were determined by the inductively coupled plasma atomic emission spectroscopy (ICP-AES). Hg and As were determined by atomic fluorescence spectroscopy (AFS). Mass balance and partitioning of trace elements have been studied to determine the fate of trace elements after retorting. By comparing the contents of different trace elements in oil shale and semi-coke, the distribution characteristics of trace elements during pyrolysis were studied. The analyses of trace element, on a whole-coal dry basis, indicate that some elements were enriched in the oil shale samples, including Mn (more than 30 ×), P (more than 6 ×), and Ti (more than 5×). The elements of Ti, Ba, Co, Cr, Cu, Mn, and V were enriched in semi-coke during retorting and could be considered as enriched in semi-coke when compared to Earth’s crust averages. Pb and Hg started to volatilize at 410°C,As and Co were enriched about 60% in semi-coke at 560°C. The release of trace elements was promoted in reducing atmosphere. The effect of heating rate on different elements can be found in these experiments. For most of elements, the characteristics of release from oil shale can be promoted by the high heating rate as well as the nitrogen atmosphere.