Mercury contamination from fuel sources has become a national environmental focus. Under a cooperative agreement with the U.S. Department of Energy, WRI has been researching and testing various western oil shales to determine their mercury content. Our laboratory tests confirmed the disposition of mercury during thermal processing. And to gain a broader understanding, we compared potential mercury issues related to oil shale to those of coal.
For this study, WRI used oil shale samples from Wyoming, Colorado and Utah. The shale was milled to a size of 200-mesh, and 100-gram samples were externally heated under an inert atmosphere. Vapor and condensate created by this thermal process were analyzed, and all were found to contain mercury. WRI researchers found that the Wyoming oil shale had 34 mg of mercury per million Btu, four times the 8 mg/MM Btu found in Powder River Basin coal. The most significant finding was that mercury is released from the oil shale within minutes when heated, and up to 80 percent is liberated in one hour by heating to 300°C.
These results are significant as the country plans national energy strategies for unconventional resources such as oil shale, because they show that mercury may be an environmental concern whether shale processing occurs above ground or below ground. Solutions for the problem, however, may be based on research already conducted for coal.
Information on this topic was presented at the 26th and 27th Oil Shale Conferences held in Golden, Colorado, in 2006 and 2007. For more information click here.