Navoi Mining & Metallurgical Combinat (NMMC), Navoi, Uzbekistan:
K. S. Sanakulov, CEO, Doctor of Engineering Sciences, Professor
O. F. Petukhov, Deputy Head of NMMC’s Central Research Laboratory Responsible for Research, Doctor of Engineering Sciences
U. Z. Sharafutdinov, Head of the Innovation Centre at NMMC, Candidate of Engineering Sciences, Associate Professor, e-mail: i.sodikov@ngmk.uz

This paper describes the results of a study that looked at uranium and vanadium extracted from refractory black shale ores. The Republic of Uzbekistan has at its disposal the mineral and man-made raw materials, as well as processing capabilities necessary for setting up production facilities. Due to their complex nature, vanadium-uranium black shale ores can potentially serve as raw materials for the rare metals industry of Uzbekistan. The main factor impeding the inclusion of such ores in the processing cycle includes the lack of feasible process for extracting vanadium and uranium from them. And the low efficiency of the proposed processing schemes was primarily attributed to a low recovery of vanadium and the difficulty of separating it from uranium. Optimal ore pre-roasting regimes have been established: temperature — 800 ^oC, consumption of sodium carbonate — 30 kg/ton, duration — 4 h. The paper presents the results of a thermal analysis of the ore roasted with sodium carbonate. It has been established that endothermic and exothermic effects take place during ore roasting with sodium carbonate. Further leaching of the roasted product under the following conditions: concentration of sulfuric acid — 70 g/l, temperature — 80 ^oC, duration — 8 h, solid-to-liquid ratio = 1:3, ensures the following recovery into solution levels: 92.9% for uranium and 82.5% for vanadium. It is shown that soaking of the roasted product at ambient temperature leads to reduced recovery of uranium and vanadium during leaching due to reverse decomposition of sodium uvanite into sodium vanadate and an insoluble uranium complex. The recommendation is that the obtained roasted product should immediately be sent for leaching.

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