Recent developments in uranium resources and production with emphasis on in situ leach mining

The northern Asia, including the southern territories of Russia, Kazakhstan, Uzbekistan, Mongolia and the northern China is known as an important distribution region of uranium deposits and occurrences. Since the 60s of 20th century, after the successful development of in-situ leach technology for sandstone-hosted uranium deposits, numerous uranium deposits previously discovered in Kazakhstan and Uzbekistan have become economically amenable low-cost uranium resources. Subsequently, prospecting efforts in Russia, Mongolia and China resulted in the discovery of a series of sandstone-hosted uranium deposits in this region. At present, most uranium deposits in above countries are located in the so-called “Central-Asia Mobile belt” and the periphery of its adjacent old continental blocks. The mobile belt is bound by the East-European and Siberian platforms from the north, and the Tarim–North-China platform from the south. Here, there occur various types of uranium deposits: volcanic-type (Streltsov, Russia), sandstone-type of interlayer oxidation zone (Kazakhstan, Uzbekistan), sandstone-type of basal-channel (Dalmatov, Russia), and metasomatite type (Elikon, Russia). It is reported, that 70–75% of uranium resources in Russia are concentrated in the mobile belt. The Central-Asia Mobile belt sandwiched in between two groups of large continental blocks experienced long tectonic evolution, including multistage extension and closure from the Baikal orogeny up to Hercynian-Indosinian orogeny resulting in the welding of the mobile belt together with the two groups of old continental blocks. Though the mobile belt experienced multiple extension, no open ocean appeared during its evolution and the belt generally represents a mature continental crust. The multiple closures led to the occurrence of numerous uranium-rich acidic-intermediate igneous rocks indicating the significant transformation of uranium and other lithophile elements towards the upper earth crust contributing to the material source of uranium ore-formation in Meso-Cenozoic basins of the mobile belt. Regardless of the occurrence of some uranium deposits in old continental blocks adjacent to the mobile belt, uranium ore-formation ages of most deposits including those located in old continental blocks show that ore-formation process occurred in Meso-Cenozoic time indicating the inherent association of uranium ore-formation with the activity of the mobile belt. The above facts suggest that the Central-Asia Mobile belt is an important global uranium metallogenic belt. Proper priority should be taken in prospecting for uranium, and special efforts should be made in locating sandstone-hosted uranium deposits amenable by ISL technology in the mobile belt.