China Nonferrous Metallurgy

As one of the main leaching methods in China at present, heap leaching of uranium ore has the advantages of low cost and no secondary pollution to the environment, but it also has the disadvantages of long leaching cycle and easy to cause blockage. In order to improve the previous problem of long uranium leaching cycles, this paper studied the uranium ore column leaching process using 5 g/L sulfuric acid and 5 g/L Fe³⁺ as leaching agent, including acidification and iron-added leaching two phases, and investigated the effects of different particle sizes and different seepage velocities on pH value, Eh value, iron concentration and uranium leaching period. The experimental results showed the percolation velocity had a significant impact on the uranium leaching cycle, that was, the faster the percolation velocity, the shorter the acidification time, and the shorter the uranium leaching cycle; at the same time, too high percolation velocity would make the leaching solution and the ore unable to fully react, resulting in a low leaching rate; the leaching period of the system (particle size of -8mm) with percolation velocity of 382.16L·h^-1·m^-2 , 178.34L·h^-1·m^-2 and 127.38L·h^-1·m^-2 (particle size of -8mm) was gradually extended, which was 38 h, 50 h and 72 h respectively, and the final uranium leaching rate was 81.14%, 84.48% and 85.02% respectively; under the condition of high speed seepage, the smaller the particle size, the longer the reaction period and the higher the leaching rate; uranium leaching rates of -5mm and -8 mm particle size systems (5g/L sulfuric acid, 5g/L Fe³⁺, 178.34L·h^-1·m^-2 percolation velocity) were 88.61% and 84.48% respectively, and the leaching cycle was 60 h and 54 h respectively. The paper aims to provide reference for green and efficient uranium leaching.