Determination of Trace Element Forms in Solvent Refined Coal Products

Abstract

The Solvent Refined Coal Processes SRC I and SRC II are designed to produce low ash, low sulfur solid (SRC I) and liquid fuels (SRC II) from coal. Both processes are currently undergoing scale-up to a 6000 tons per day demonstration plant stage. The fate and distribution of Ti, V, Ca, Mg, Al, CI, Mn, As, Se, Sb, Hg, Br, Ni, Co, Cr, Fe, Na, Rb, Cs, K, Sc, Eu, Sm, Ce, La, Sr, Ba, Th, Hf, Ta, Zr and Cu in the SRC I and SRC II processes have been determined using neutron activation analysis. The nature of the chemical species of several elements has been investigated using fission track analysis for U and a combination of gel permeation chromatography, HPLC, activation analysis and atomic absorption spectroscopy for other elements. In solid SRC I, U was measured to be 0.266 ppm and it was also found that the U was distributed inhomogeneously. The concentration of U on mineral particulates was found to be approximately 76 ppm, thus ruling out U minerals. In SRC I it was established that Ti, V, As, Ga, Fe, Zn, and Se showed distinct organic affinity and that these elements were probably present as metal-organic complexes or complexed in the asphaltene or preasphaltene structure. The nature of these complexes could not be established, but for Ti and V there is a strong possibility of phenolic-type complexes.