Study On The Kinetics For Acidic Surface Heap Leaching Of Uranium Ore

At present the Chinese uranium resources are characterized by more mineralizationtypes, small scale and shallow buried, and a large proportion of low-grade uraniumore for hard rock, therefore we use a method of heap leaching mining mostly, acidicsurface technology of heap leaching is the main technology of production, although ithas many advantages, but it exists many problems like the longer time leaching, thelower leaching rate of uranium and later the sharp drop of metal concentration in theleaching solution and so on. So studying on the behavior of and establishing kineticsfor acidic surface heap leaching of uranium ore, will provide an accurate theoreticalsupport on submitting new extraction technology and improving the existingtechnologies, will provide important practical significance on reducing the extractiontime, strengthening the leaching process and improving the leaching rate of metal.Nowadays, the most common of heap leaching kinetics is “Liquid-Solid ReactionKinetics”, however, the establishing of some of these models has an importantprecondition: the reactant concentration of solvent c0does not change by the time. Infact, it will decrease with the depth of the heap during the practice of heap leaching.In order to remove the defects mentioned above, and to establish kinetic model foracidic surface heap leaching of uranium ore, the paper introduced the model ofMellado and carried out3groups of independent experiment, then got the conclusionsas:(1) The paper validated the model of Mellado by interior column leachingexperiments of narrow size fraction uranium ore, and confirmed that it could be usedto analysis the law of heap leaching of narrow size fraction uranium ore. Moreover,for the3groups of narrow size fraction uranium ore, the corresponding changes of themodel parametersk、k ’were small but in opposite of、, obviously, it was related to the changing of the average particle size of the ore.(2) The paper validated the improved model of Mellado by interior columnleaching experiments of natural size fraction uranium ore, and confirmed that it couldalso be used to analysis the law of heap leaching of natural size fraction uranium orein different depth of the heap. According to the results of the experiment, it was foundthat the model parameters and for heap leaching of the uranium ore variedwith the depth of the heap, and then a kinetic model for heap leaching of the uraniumore considering the variation of the model parameters with the depth of the ore wasproposed. The kinetic model gave the fitting precision of more than95%andprediction precision of more than93%.(3) The paper represented the widely distributed characteristics of particle with thefractal dimension of particle basing on the fractal theory, and then improved themodel of Mellado and established a fractal kinetic model for heap leaching ofuranium ore by interior column leaching experiments of the fractal dimensionuranium ore, meanwhile, the paper verified it further by a column leachingexperiment which show that the fractal kinetic model can well reflect the law ofuranium metal leaching of heap leaching of uranium ore.