JJEES Volume 4 (Special Publication, Number 2), Jan. 2012 ISSN 1995-6681 Pages 29- 34 Jordan Journal of Earth and Environmental Sciences The Leachability Propensity of El-Lajjun Jordanian Oil Shale Ash Adnan Al-Harahsheh a,b,* , Awni Al-Otoom c , Mohammad Al-Harahsheh d , Mamdouh Allawzi c , Rida Al-Adamat b , a Mohammed Al-Farajat b , Omar Al-Ayed e a Department of Chemical Engineering, Mutah University, Karak Jordan b Institute of Earth & Environmental Sciences, Al al-Bayt University, Al-Mafraq, Jordan c Department of Chemical Engineering, Jordan University of Science and Technology, Irbid, Jordan d Department of Mining Engineering, Al-Hussein Bin Talal University, Ma’an, Jordan e Department of Chemical Engineering, Al-Balqa Applied University, Amman Jordan Abstract This work reports the leachability of heavy metals and major anions from Jordanian spent oil shale after combustion. Oil shale samples were combusted at temperatures of 550C, 650C, 750C and 850C. Characterization of the produced solid ash was performed based on XRD analyses. Leaching tests on the ash samples were conducted for different periods of time. Experimental results indicate that the level of heavy metals such as Cd, Pb, Zn, Cu, Cr in the leachate is below the maximum levels set by the Environmental Protection Authority (EPA). For instance, the maximum level of Cd measured in the leachate solution was 0.14 ppm, which is below the EPA limit. Results also indicate that even though the level of heavy metals in all samples was below the EPA limits, yet the level of heavy metals increases as the temperature of the ashing process increases. The effect of ashing temperature on ash cation exchange capacity (CEC) and the pH of ash solution were studied and found to increase with increasing ashing temperature. © 2012 Jordan Journal of Earth and Environmental Sciences. All rights reserved Keywords: Oil Shale; Ash; Leachability; Heavy Metals.Introduction * * Corresponding author. e-mail: adnan@mutah.edu.jo. 1. Introduction Jordan has limited energy resources such as crude oil or natural gas compared to its neighboring countries. However, oil shale is an important and unutilized energy source in the country. More than 50 billion tons of oil shale deposits are discovered in different areas especially in the middle and southern parts of the country (Dabbas, 1997). The soaring prices of oil have led many investors to consider oil- alternative energy resources. The oil equivalent of oil shale around the world is estimated to be around 30 times the reserve of the crude oil (Russell, 1990). Commercialization of Jordanian oil shale in the form of utilizable oil is being studied. The high percentage of ash in the Jordanian oil shale (50-60%) makes the future of utilization of oil shale as a source of liquid fuel uncertain (Jaber et al., 1999). One method is widely used in utilizing oil shale is the retorting process. This process involves extraction of bituminous oil at elevated temperatures in non-oxidizing conditions. There are growing concerns over the fate of spent shale after retorting process. One of these concerns is mainly the leachability propensity of trace elements of the spent oil shale into underground water. The chemical nature of the minerals in the spent shale can change considerably during both the retorting and the combustion stages. These chemical changes will affect both the physical and chemical stability of the spent shale and are important when determining disposal strategies for the waste solid (Bell et al., 1986). Disposal of mining wastes, spent shale (semicoke) and combustion ashes needs additional land use. According to the study of the European Academies Science Advisory Council (Francu et al., 2007), after processing, the waste material occupies a greater volume than the material extracted, and therefore cannot be wholly disposed underground. The primary threat to water quality is generally considered to be the leachate from spent, i.e. retorted, oil shale. Typically oil shale retorting result in the generation of slightly over one tone of spent shale per barrel of shale oil (EASAC, 2007) . In order to study the migratory behavior of trace elements in oil shale at retorting, tests were performed in laboratory with oil shale of the Huadian deposit of China at different temperature from 360 to 560 o C (Bai et al.,