The Effect of Particle Size, Irrigation Rate and Aeration Rate on Column Bioleaching of Uranium Ore¹

Abstract—The effect of hydrodynamic factors such as particle size, irrigation rate and aeration rate on the dissolution of uranium by Acidithibacillus ferrooxidans in column reactor was studied. Response surface methodology (RSM) was applied to predict the behavior of effective parameters and their interactions on the bioleaching process. Under the optimum conditions particle size of 5 mm, irrigation rate of 0.34 L/m²/min and aeration rate of 210 L/m²/min, the maximum value of uranium recovery was 63.85% for 19 days. The results from the statistical model and the experimental data showed good agreement and the most effective factor was the aeration rate. The interaction between particle size and irrigation rate has a negative effect and two other interactions have a positive effect on uranium recovery. Analysis of bioleaching residue confirmed the formation of K-jarosite on the surface of particles. The modified kinetic model at optimum conditions showed that cathodic ferric reduction is the rate controlling step on uranium bioleaching recovery.