Uranium Mining in Namibia
Uranium minerals were first recognized in the vicinity of today’s Rössing Mine in 1928. But it was not until Rio Tinto acquired exploration rights in the 1960s, that a number of low-grade ore bodies were discovered along the north side of the rugged Khan valley. After extensive test work, the Rössing Mine was opened in 1976 and proudly celebrates its 40th birthday this year. Following the establishment of the Rössing Mine and a global increase in the demand for uranium for nuclear energy production during the 1960s and 1970s, several other companies started uranium exploration in the central Namib. More uranium deposits were identified, but the uranium price slowly declined and hence no other mines opened up for a long time. This changed early in the new millennium, when increasing uranium prices allowed the development of the Langer Heinrich Mine, which started production in 2006. It was also around that time that uranium prices reached an all-time high, and extensive exploration was undertaken once again in the western Erongo Region. Assisted by high-resolution airborne geophysical data provided by the Geological Survey of Namibia this exploration led to the discovery of the Husab ore body, a world-class uranium deposit, currently being turned into the world’s second largest uranium mine. In addition, a number of other projects are in advanced stages of exploration and test work for uranium extraction from the ore. However, uranium prices are once again depressed, and the full development of these projects awaits an increase in the price of the commodity.
The uranium deposits of the central Namib belong to two main types, namely primary uranium mineralization in light-coloured granite, so-called alaskite (Rössing, Husab), and secondary uranium mineralization in calcrete (Langer Heinrich). Secondary mineralization is the result of weathering of rocks with primary mineralization. Uranium-bearing alaskites have intruded the metamorphosed sediments of the Khan and Rössing Formations some 450 million years ago. The predominant uranium mineral in alaskite is uraninite [UO2], but betafite [U(Nb,Ti)2O6(OH)] can be a major mineral phase in some places. Secondary uranium deposits are found in calcrete which formed in palaeo-valleys of ancient rivers that flowed westwards from the Great Escarpment some 88 to 25 million years ago. The main uranium mineral in calcrete is carnotite [K2(UO2)2(VO4)2 x 3H2O]. It occurs as a thin film in cracks and as a coating on sediment grains in the calcretized fluvial channels. Both mineralisation types are amenable to open cast mining methods.
Uranium mining is an important economic factor in Namibia and in the Erongo Region in particular, where it has created substantial employment opportunities not only in the mining industry, but also in the supply and service industry. With more new nuclear power plants under construction worldwide than at any other time in the last 25 years, linked to the urgent need for electricity generation with low CO2emissions, uranium prices are expected to improve with time. This will enable the uranium mining industry to prosper and grow, and continue to play its important role in the socio-economic development of the Erongo Region and indeed Namibia as a whole.