Israeli oil shales as an alternative raw material for Portland cement production

Oil shale is a horizontally layered rock that contains a mix of clay minerals and calcium carbonate that have rich contents of an organic material called kerogen. The mineral and organic composition of oil shales vary greatly depending on the deposits and the layers from which they are extracted. Oil shale with high organic content is used to extract oil, gas, or for direct combustion in power plants to generate electricity. Silica-rich oil shale ash resulting from the combustion can be used as a pozzolanic material and can be added to clinker in cement production. Significant oil shale deposits have been found in Israel. Most of the deposits are concentrated in the northern Negev. Israeli oil shale contains a small amount of kerogen with low calorific value, so using it as a fuel in power plants is unprofitable. The mineral part of Israeli oil shale is more than 70% by weight. From the chemical point of view, the major component is calcium oxide, the second important component is silica, and the alumina and iron oxides, as well as some impurities, are also present. The content of silica in Israeli oil shale is less than 25%, which means it is lacking pozzolanic properties and cannot be used as an additive to clinker. However, the ratio of major oxides in oil shales is very similar to the ratio of major oxides in the clinker. Thus, Israeli oil shale could be potentially used for clinker production. This project aimed to study Israeli oil shale as a raw material for clinker production. With this aim, a detailed chemical, mineralogical, and physical analysis of 3 layers (upper, middle, lower) of oil shales was carried out. Based on this analysis, a clinker raw meal composition with the maximum content of oil shale in the clinker raw meal (76%) was calculated, as well as a clinker with the optimal amount of oil shale (35-39%) and the trial batches of clinkers were produced in the laboratory. The optimal conditions for clinker production were selected and the main problems associated with impurities such as phosphorus and sulfur oxides were identified and resolved. The grinding mode was optimized, and the optimum amount of gypsum was experimentally determined for cement production. The quality of obtained cement was tested for compliance with the standard requirements such as strength, soundness, and setting times. It was demonstrated that cement obtained from oil shale meets all the requirements of the Portland cement standard.