Comprehensive processing methods for oil shale from the Aktau deposit (Uzbekistan)

Oil shale reserves in Uzbekistan amount to over 47 billion tons and are notable for fairly high grades of various metals. Additional research is therefore required to establish whether their useful components, such as uranium, vanadium, molybdenum, etc., may be effectively recovered in processing. This work analyzes the pilot oil shale processing technologies that are currently in use or have been previously proposed. The study was conducted for the oil shale of the Aktau deposit. A study of the mineral composition and forms of occurrence of the relevant valuable components has shown that the initial raw material consists mainly of hydromica-carbonate-quartz or clay-carbonate-quartz shales. Experiments were conducted and thermal decomposition parameters were established for the Aktau oil shale without exposure to oxygen (pyrolysis). The optimal parameters for obtaining liquid (13 %) and gas (7.9 %) fractions and semi-coke (79.1 %) were identified. As a result of the studies, semicoke sulfuric acid leaching was proposed for the recovery of valuable metals (molybdenum and vanadium), followed by selective separation of these components in the metal-containing solution using ion exchange resins. The experiments have rendered the throughout recoveries of molybdenum at over 85 % and of vanadium at 66 %. The recommended associated recovery of such useful components as vanadium and molybdenum from semi-coke will significantly improve economic efficiency in the processing of oil shale from the Aktau deposit and generate marketable products worth approximately $50,483 from each 1000 tons of raw materials.

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