Выбор способа выщелачивания молибдена на основе термодинамических и кинетических критериев

Abstract

Выполнен термодинамический и кинетический анализ процессов кислотного и щелочного извлечения молибдена на примере переработки оксидного железо-молибденового катализатора конверсии метанола. Выщелачивание проводили в условиях модельного циркуляционного реактора с неподвижной твердой фазой. Найдено, что при скорости потока растворов через слой частиц твердой фазы не менее 0,04 м/с процессы выщелачивания лимитируются стадией диффузии через слой продукта химической реакции. Впервые теоретически и экспериментально обоснован выбор оптимального реагента для выщелачивания молибдена.A thermodynamic and kinetic analysis of the processes of acid and alkaline extraction of molybdenum oxide considered in example of processing iron-molybdenum catalyst methanol conversion was carried out. Leaching was realized in cycled reactor model with a solid fixed phase. It was found that at a flow rate of solutions through the layer of solid particles is not less than 0.04 m/s is limited by the leaching step by the diffusion layer of the product of the chemical reaction. First time theoretically and experimentally based choice of the optimal reagent for the leaching of molybdenum was done. Furthermore, comparative analysis of the leaching process of molybdenum showed that the best reagent should be considered a concentrated solution of ammonia. Also it was showed that in a row NaOH > Na₂CO₃ > H₂SO₄ > NH₄OH speed of iron molybdate decomposition decreases. Thermodynamic data showed that the optimal pH value of leaching is 12 – 13. In case if pH value more than 13, the degree of purity of molybdate solutions is increases. It was found that the decomposition of iron molybdate by sulfuric acid solution is possible only in excess of solution of sodium sulfate or ammonium.