Leachability of Oil Shale Ash from Isfir Al-Mahata Oil Shale, Southern Jordan

Abstract

This paper presents the first study on the oil shale (OS) ashing and OS ash leachability of Jordanian OS located further in the south. The studied OS is from Isfir Al-Mahata subsurface OS located 10 km south of Ma’an. Chemical and physical characterization of the OS ash was performed and compared with original OS. Ashing OS was conducted at different temperatures. Important parameters affecting OS ash leachability were also investigated. The leachability of certain heavy metals was investigated based on clear leaching protocol. The Fisher Assay analysis result indicates that this OS type has quite higher moisture content, lower oil content, and higher spent shale compared with other Jordanian oil shales. Ashing of OS at higher temperatures (950°C) resulted in the disappearance of silica, due to its complete reaction with lime and Al, and formation of Anhydrite and cement materials like, Portland cement. The leachability analysis indicates that for most elements the leachability is high at low pH. The released heavy metals concentrations are below EPA limits. Chromium and lead are leached out more than other elements with the exception at low pH. In general, the higher the ashing temperature is, the lower the release of elements is. The chemical composition of the ash and the leachability results suggests that it has high fixing capacity toward the heavy metals present in the ash.