Neutralization of Acidic Industrial Wastes and Fixation of Trace Element by Oil Shale Ash: Formation of a Green Product

Oil shale is a rock that contains organic matter in a concentration that allows it to be used as an energy source. As a result of the shale combustion process, large amounts of two types of ash are formed: fly ash (∼10%) and bottom ash (∼90%). At present, in Israel, only fly oil shale ash is used, which constitutes a minority of the oil shale burn products, whereas bottom oil shale ash is accumulated as waste. Bottom ash contains a high percentage of calcium in the form of anhydrite (CaSO₄) and calcite (CaCO₃). Thus, it can be used to neutralize acidic waste and to fix trace elements. This study examined the process of scrubbing the acid waste by the ash, its characterization pre- and post-upgrade treatment, to test its suitability as a partial substitute for aggregates, natural sand, and cement in concrete mixtures. In the current study, we compared the chemical and physical characterization of oil shale bottom ash before and after upgrading the ash via chemical treatment. In addition, its utilization as a scrubbing reagent for acidic wastes from the phosphate industry was studied.