Uranium circuit development for a West African polymetallic deposit

This article presents the process flow sheet development conducted in 2013 on a polymetallic deposit located in West Africa. The mineralization, consisting of uranium and to a lesser extent silver and copper, posed challenges due to the presence of high levels of both carbonates (acid consumers) and sulphides (alkali consumers). It was established that copper and silver were associated with the sulphides and could be separated by means of flotation. Thus a trade-off study was conducted to evaluate both alkali and acid processing routes for the recovery of uranium. The following two flow sheets were investigated: 1. Acid leaching of the run-of-mine (ROM) ore, followed by sulphide flotation of leach tails for the recovery of silver and copper from the concentrate 2. Sulphide flotation of the ROM ore for silver and copper recovery, followed by alkali leaching of the float tails for uranium recovery. The trade-off study showed a differential operating cost saving of between 10% and 40%, within a 90% confidence level, in favour of the alkali-based flow sheet, which was selected for further evaluation and optimization. Further flow sheet development was also conducted to determine the following: ➤ Alkali addition and minimizing water requirements ➤ Processing of flotation concentrates to produce saleable silver and copper by products.